[RESEND,v2,1/2] iio: temperature: Add support for LTC2983

Commit Message

Nuno Sa Sept. 30, 2019, 10:42 a.m. UTC

The LTC2983 is a Multi-Sensor High Accuracy Digital Temperature
Measurement System. It measures a wide variety of temperature sensors and
digitally outputs the result, in °C or °F, with 0.1°C accuracy and
0.001°C resolution. It can measure the temperature of all standard
thermocouples (type B,E,J,K,N,S,R,T), standard 2-,3-,4-wire RTDs,
thermistors and diodes.

Signed-off-by: Nuno Sá <[e-mail]>
---
Changes in v2:
 * Added some needed blank lines (for readability);
 * Allocate iio_chan in the setup() function;
 * Rename reset to sleep;
 * Remove unneeded dev_dbg calls;
 * Remove unneeded line wrapping;
 * Remove unneeded comments;
 * Remove extend_names. Use the standard ABI;
 * Adapt the scales to report in millivolt and milli degrees;
 * Adapt the of_property readings to the renaming of the properties;
 * For custom thermistors, excitation-current cannot be set to Auto range.

 MAINTAINERS                       |    7 +
 drivers/iio/temperature/Kconfig   |   10 +
 drivers/iio/temperature/Makefile  |    1 +
 drivers/iio/temperature/ltc2983.c | 1436 +++++++++++++++++++++++++++++
 4 files changed, 1454 insertions(+)
 create mode 100644 drivers/iio/temperature/ltc2983.c

Comments

Jonathan Cameron Oct. 1, 2019, 9:03 a.m. UTC | #1

On Mon, 30 Sep 2019 12:42:46 +0200
Nuno Sá <[e-mail]> wrote:

> The LTC2983 is a Multi-Sensor High Accuracy Digital Temperature
> Measurement System. It measures a wide variety of temperature sensors and
> digitally outputs the result, in °C or °F, with 0.1°C accuracy and
> 0.001°C resolution. It can measure the temperature of all standard
> thermocouples (type B,E,J,K,N,S,R,T), standard 2-,3-,4-wire RTDs,
> thermistors and diodes.
> 
> Signed-off-by: Nuno Sá <[e-mail]>

One minor comment inline.  I don't see a reason to use a threaded irq
to simply set a completion. Just do it with a traditional irq.
I suspect the overhead of doing that is probably similar to spinning
up the irq thread.

Otherwise, I'm happy with this subject to binding review.

Thanks,

Jonathan

> ---
> Changes in v2:
>  * Added some needed blank lines (for readability);
>  * Allocate iio_chan in the setup() function;
>  * Rename reset to sleep;
>  * Remove unneeded dev_dbg calls;
>  * Remove unneeded line wrapping;
>  * Remove unneeded comments;
>  * Remove extend_names. Use the standard ABI;
>  * Adapt the scales to report in millivolt and milli degrees;
>  * Adapt the of_property readings to the renaming of the properties;
>  * For custom thermistors, excitation-current cannot be set to Auto range.
> 
>  MAINTAINERS                       |    7 +
>  drivers/iio/temperature/Kconfig   |   10 +
>  drivers/iio/temperature/Makefile  |    1 +
>  drivers/iio/temperature/ltc2983.c | 1436 +++++++++++++++++++++++++++++
>  4 files changed, 1454 insertions(+)
>  create mode 100644 drivers/iio/temperature/ltc2983.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index f0c03740b9fb..14a256e785ca 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -9491,6 +9491,13 @@ S:	Maintained
>  F:	Documentation/devicetree/bindings/iio/dac/ltc1660.txt
>  F:	drivers/iio/dac/ltc1660.c
>  
> +LTC2983 IIO TEMPERATURE DRIVER
> +M:	Nuno Sá <[e-mail]>
> +W:	http://ez.analog.com/community/linux-device-drivers
> +L:	[e-mail]
> +S:	Supported
> +F:	drivers/iio/temperature/ltc2983.c
> +
>  LTC4261 HARDWARE MONITOR DRIVER
>  M:	Guenter Roeck <[e-mail]>
>  L:	[e-mail]
> diff --git a/drivers/iio/temperature/Kconfig b/drivers/iio/temperature/Kconfig
> index 737faa0901fe..04b5a67b593c 100644
> --- a/drivers/iio/temperature/Kconfig
> +++ b/drivers/iio/temperature/Kconfig
> @@ -4,6 +4,16 @@
>  #
>  menu "Temperature sensors"
>  
> +config LTC2983
> +	tristate "Analog Devices Multi-Sensor Digital Temperature Measurement System"
> +	depends on SPI
> +	help
> +	  Say yes here to build support for the LTC2983 Multi-Sensor
> +	  high accuracy digital temperature measurement system.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called ltc2983.
> +
>  config MAXIM_THERMOCOUPLE
>  	tristate "Maxim thermocouple sensors"
>  	depends on SPI
> diff --git a/drivers/iio/temperature/Makefile b/drivers/iio/temperature/Makefile
> index baca4776ca0d..d6b850b0cf63 100644
> --- a/drivers/iio/temperature/Makefile
> +++ b/drivers/iio/temperature/Makefile
> @@ -3,6 +3,7 @@
>  # Makefile for industrial I/O temperature drivers
>  #
>  
> +obj-$(CONFIG_LTC2983) += ltc2983.o
>  obj-$(CONFIG_HID_SENSOR_TEMP) += hid-sensor-temperature.o
>  obj-$(CONFIG_MAXIM_THERMOCOUPLE) += maxim_thermocouple.o
>  obj-$(CONFIG_MAX31856) += max31856.o
> diff --git a/drivers/iio/temperature/ltc2983.c b/drivers/iio/temperature/ltc2983.c
> new file mode 100644
> index 000000000000..7c159da9f183
> --- /dev/null
> +++ b/drivers/iio/temperature/ltc2983.c
> @@ -0,0 +1,1436 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Analog Devices LTC2983 Multi-Sensor Digital Temperature Measurement System
> + * driver
> + *
> + * Copyright 2019 Analog Devices Inc.
> + */
> +#include <linux/bitfield.h>
> +#include <linux/completion.h>
> +#include <linux/device.h>
> +#include <linux/kernel.h>
> +#include <linux/iio/iio.h>
> +#include <linux/interrupt.h>
> +#include <linux/list.h>
> +#include <linux/module.h>
> +#include <linux/of_gpio.h>
> +#include <linux/regmap.h>
> +#include <linux/spi/spi.h>
> +
> +/* register map */
> +#define LTC2983_STATUS_REG			0x0000
> +#define LTC2983_TEMP_RES_START_REG		0x0010
> +#define LTC2983_TEMP_RES_END_REG		0x005F
> +#define LTC2983_GLOBAL_CONFIG_REG		0x00F0
> +#define LTC2983_MULT_CHANNEL_START_REG		0x00F4
> +#define LTC2983_MULT_CHANNEL_END_REG		0x00F7
> +#define LTC2983_MUX_CONFIG_REG			0x00FF
> +#define LTC2983_CHAN_ASSIGN_START_REG		0x0200
> +#define LTC2983_CHAN_ASSIGN_END_REG		0x024F
> +#define LTC2983_CUST_SENS_TBL_START_REG		0x0250
> +#define LTC2983_CUST_SENS_TBL_END_REG		0x03CF
> +
> +#define LTC2983_DIFFERENTIAL_CHAN_MIN		2
> +#define LTC2983_MAX_CHANNELS_NR			20
> +#define LTC2983_MIN_CHANNELS_NR			1
> +#define LTC2983_SLEEP				0x97
> +#define LTC2983_CUSTOM_STEINHART_SIZE		24
> +#define LTC2983_CUSTOM_SENSOR_ENTRY_SZ		6
> +#define LTC2983_CUSTOM_STEINHART_ENTRY_SZ	4
> +
> +#define LTC2983_CHAN_START_ADDR(chan) \
> +			(((chan - 1) * 4) + LTC2983_CHAN_ASSIGN_START_REG)
> +#define LTC2983_CHAN_RES_ADDR(chan) \
> +			(((chan - 1) * 4) + LTC2983_TEMP_RES_START_REG)
> +#define LTC2983_THERMOCOUPLE_DIFF_MASK		BIT(3)
> +#define LTC2983_THERMISTOR_DIFF_MASK		BIT(2)
> +#define LTC2983_DIODE_DIFF_MASK			BIT(2)
> +#define LTC2983_RTD_4_WIRE_MASK			BIT(3)
> +#define LTC2983_RTD_ROTATION_MASK		BIT(1)
> +#define LTC2983_RTD_KELVIN_R_SENSE_MASK		GENMASK(3, 2)
> +
> +#define LTC2983_COMMON_HARD_FAULT_MASK	GENMASK(31, 30)
> +#define LTC2983_COMMON_SOFT_FAULT_MASK	GENMASK(27, 25)
> +
> +#define	LTC2983_STATUS_START_MASK	BIT(7)
> +#define	LTC2983_STATUS_START(x)		FIELD_PREP(LTC2983_STATUS_START_MASK, x)
> +
> +#define	LTC2983_STATUS_CHAN_SEL_MASK	GENMASK(4, 0)
> +#define	LTC2983_STATUS_CHAN_SEL(x) \
> +				FIELD_PREP(LTC2983_STATUS_CHAN_SEL_MASK, x)
> +
> +#define LTC2983_TEMP_UNITS_MASK		BIT(2)
> +#define LTC2983_TEMP_UNITS(x)		FIELD_PREP(LTC2983_TEMP_UNITS_MASK, x)
> +
> +#define LTC2983_NOTCH_FREQ_MASK		GENMASK(1, 0)
> +#define LTC2983_NOTCH_FREQ(x)		FIELD_PREP(LTC2983_NOTCH_FREQ_MASK, x)
> +
> +#define LTC2983_RES_VALID_MASK		BIT(24)
> +#define LTC2983_DATA_MASK		GENMASK(23, 0)
> +#define LTC2983_DATA_SIGN_BIT		23
> +
> +#define LTC2983_CHAN_TYPE_MASK		GENMASK(31, 27)
> +#define LTC2983_CHAN_TYPE(x)		FIELD_PREP(LTC2983_CHAN_TYPE_MASK, x)
> +
> +/* cold junction for thermocouples and rsense for rtd's and thermistor's */
> +#define LTC2983_CHAN_ASSIGN_MASK	GENMASK(26, 22)
> +#define LTC2983_CHAN_ASSIGN(x)		FIELD_PREP(LTC2983_CHAN_ASSIGN_MASK, x)
> +
> +#define LTC2983_CUSTOM_LEN_MASK		GENMASK(5, 0)
> +#define LTC2983_CUSTOM_LEN(x)		FIELD_PREP(LTC2983_CUSTOM_LEN_MASK, x)
> +
> +#define LTC2983_CUSTOM_ADDR_MASK	GENMASK(11, 6)
> +#define LTC2983_CUSTOM_ADDR(x)		FIELD_PREP(LTC2983_CUSTOM_ADDR_MASK, x)
> +
> +#define LTC2983_THERMOCOUPLE_CFG_MASK	GENMASK(21, 18)
> +#define LTC2983_THERMOCOUPLE_CFG(x) \
> +				FIELD_PREP(LTC2983_THERMOCOUPLE_CFG_MASK, x)
> +#define LTC2983_THERMOCOUPLE_HARD_FAULT_MASK	GENMASK(31, 29)
> +#define LTC2983_THERMOCOUPLE_SOFT_FAULT_MASK	GENMASK(28, 25)
> +
> +#define LTC2983_RTD_CFG_MASK		GENMASK(21, 18)
> +#define LTC2983_RTD_CFG(x)		FIELD_PREP(LTC2983_RTD_CFG_MASK, x)
> +#define LTC2983_RTD_EXC_CURRENT_MASK	GENMASK(17, 14)
> +#define LTC2983_RTD_EXC_CURRENT(x) \
> +				FIELD_PREP(LTC2983_RTD_EXC_CURRENT_MASK, x)
> +#define LTC2983_RTD_CURVE_MASK		GENMASK(13, 12)
> +#define LTC2983_RTD_CURVE(x)		FIELD_PREP(LTC2983_RTD_CURVE_MASK, x)
> +
> +#define LTC2983_THERMISTOR_CFG_MASK	GENMASK(21, 19)
> +#define LTC2983_THERMISTOR_CFG(x) \
> +				FIELD_PREP(LTC2983_THERMISTOR_CFG_MASK, x)
> +#define LTC2983_THERMISTOR_EXC_CURRENT_MASK	GENMASK(18, 15)
> +#define LTC2983_THERMISTOR_EXC_CURRENT(x) \
> +			FIELD_PREP(LTC2983_THERMISTOR_EXC_CURRENT_MASK, x)
> +
> +#define LTC2983_DIODE_CFG_MASK		GENMASK(26, 24)
> +#define LTC2983_DIODE_CFG(x)		FIELD_PREP(LTC2983_DIODE_CFG_MASK, x)
> +#define LTC2983_DIODE_EXC_CURRENT_MASK	GENMASK(23, 22)
> +#define LTC2983_DIODE_EXC_CURRENT(x) \
> +				FIELD_PREP(LTC2983_DIODE_EXC_CURRENT_MASK, x)
> +#define LTC2983_DIODE_IDEAL_FACTOR_MASK	GENMASK(21, 0)
> +#define LTC2983_DIODE_IDEAL_FACTOR(x) \
> +				FIELD_PREP(LTC2983_DIODE_IDEAL_FACTOR_MASK, x)
> +
> +#define LTC2983_R_SENSE_VAL_MASK	GENMASK(26, 0)
> +#define LTC2983_R_SENSE_VAL(x)		FIELD_PREP(LTC2983_R_SENSE_VAL_MASK, x)
> +
> +#define LTC2983_ADC_SINGLE_ENDED_MASK	BIT(26)
> +#define LTC2983_ADC_SINGLE_ENDED(x) \
> +				FIELD_PREP(LTC2983_ADC_SINGLE_ENDED_MASK, x)
> +
> +enum {
> +	LTC2983_SENSOR_THERMOCOUPLE = 1,
> +	LTC2983_SENSOR_THERMOCOUPLE_CUSTOM = 9,
> +	LTC2983_SENSOR_RTD = 10,
> +	LTC2983_SENSOR_RTD_CUSTOM = 18,
> +	LTC2983_SENSOR_THERMISTOR = 19,
> +	LTC2983_SENSOR_THERMISTOR_STEINHART = 26,
> +	LTC2983_SENSOR_THERMISTOR_CUSTOM = 27,
> +	LTC2983_SENSOR_DIODE = 28,
> +	LTC2983_SENSOR_SENSE_RESISTOR = 29,
> +	LTC2983_SENSOR_DIRECT_ADC = 30,
> +};
> +
> +#define to_thermocouple(_sensor) \
> +		container_of(_sensor, struct ltc2983_thermocouple, sensor)
> +
> +#define to_rtd(_sensor) \
> +		container_of(_sensor, struct ltc2983_rtd, sensor)
> +
> +#define to_thermistor(_sensor) \
> +		container_of(_sensor, struct ltc2983_thermistor, sensor)
> +
> +#define to_diode(_sensor) \
> +		container_of(_sensor, struct ltc2983_diode, sensor)
> +
> +#define to_rsense(_sensor) \
> +		container_of(_sensor, struct ltc2983_rsense, sensor)
> +
> +#define to_adc(_sensor) \
> +		container_of(_sensor, struct ltc2983_adc, sensor)
> +
> +struct ltc2983_data {
> +	struct regmap *regmap;
> +	struct spi_device *spi;
> +	struct mutex lock;
> +	struct completion completion;
> +	struct iio_chan_spec *iio_chan;
> +	struct ltc2983_sensor **sensors;
> +	u32 mux_delay_config;
> +	u32 filter_notch_freq;
> +	u16 custom_table_size;
> +	u8 num_channels;
> +	u8 iio_channels;
> +	bool temp_farenheit;
> +	bool sleep;
> +};
> +
> +struct ltc2983_sensor {
> +	int (*fault_handler)(const struct ltc2983_data *st, const u32 result);
> +	int (*assign_chan)(struct ltc2983_data *st,
> +			   const struct ltc2983_sensor *sensor);
> +	/* specifies the sensor channel */
> +	u32 chan;
> +	/* sensor type */
> +	u32 type;
> +};
> +
> +struct ltc2983_custom_sensor {
> +	/* raw table sensor data */
> +	u8 *table;
> +	size_t size;
> +	/* address offset */
> +	s8 offset;
> +	bool is_steinhart;
> +};
> +
> +struct ltc2983_thermocouple {
> +	struct ltc2983_sensor sensor;
> +	struct ltc2983_custom_sensor *custom;
> +	u32 sensor_config;
> +	u32 cold_junction_chan;
> +};
> +
> +struct ltc2983_rtd {
> +	struct ltc2983_sensor sensor;
> +	struct ltc2983_custom_sensor *custom;
> +	u32 sensor_config;
> +	u32 r_sense_chan;
> +	u32 excitation_current;
> +	u32 rtd_curve;
> +};
> +
> +struct ltc2983_thermistor {
> +	struct ltc2983_sensor sensor;
> +	struct ltc2983_custom_sensor *custom;
> +	u32 sensor_config;
> +	u32 r_sense_chan;
> +	u32 excitation_current;
> +};
> +
> +struct ltc2983_diode {
> +	struct ltc2983_sensor sensor;
> +	u32 sensor_config;
> +	u32 excitation_current;
> +	u32 ideal_factor_value;
> +};
> +
> +struct ltc2983_rsense {
> +	struct ltc2983_sensor sensor;
> +	u32 r_sense_val;
> +};
> +
> +struct ltc2983_adc {
> +	struct ltc2983_sensor sensor;
> +	bool single_ended;
> +};
> +
> +/*
> + * Convert to Q format numbers. These number's are integers where
> + * the number of integer and fractional bits are specified. The resolution
> + * is given by 1/@resolution and tell us the number of fractional bits. For
> + * instance a resolution of 2^-10 means we have 10 fractional bits.
> + */
> +static u32 __convert_to_raw(const u64 val, const u32 resolution)
> +{
> +	u64 __res = val * resolution;
> +
> +	/* all values are multiplied by 1000000 to remove the fraction */
> +	do_div(__res, 1000000);
> +
> +	return __res;
> +}
> +
> +static u32 __convert_to_raw_sign(const u64 val, const u32 resolution)
> +{
> +	s64 __res = -(s32)val;
> +
> +	__res = __convert_to_raw(__res, resolution);
> +
> +	return (u32)-__res;
> +}
> +
> +static int __ltc2983_fault_handler(const struct ltc2983_data *st,
> +				   const u32 result, const u32 hard_mask,
> +				   const u32 soft_mask)
> +{
> +	const struct device *dev = &st->spi->dev;
> +
> +	if (result & hard_mask) {
> +		dev_err(dev, "Invalid conversion: Sensor HARD fault\n");
> +		return -EIO;
> +	} else if (result & soft_mask) {
> +		/* just print a warning */
> +		dev_warn(dev, "Suspicious conversion: Sensor SOFT fault\n");
> +	}
> +
> +	return 0;
> +}
> +
> +static int __ltc2983_chan_assign_common(const struct ltc2983_data *st,
> +					const struct ltc2983_sensor *sensor,
> +					u32 chan_val)
> +{
> +	u32 reg = LTC2983_CHAN_START_ADDR(sensor->chan);
> +	__be32 __chan_val;
> +
> +	chan_val |= LTC2983_CHAN_TYPE(sensor->type);
> +	dev_dbg(&st->spi->dev, "Assign reg:0x%04X, val:0x%08X\n", reg,
> +								chan_val);
> +	__chan_val = cpu_to_be32(chan_val);
> +	return regmap_bulk_write(st->regmap, reg, &__chan_val,
> +				 sizeof(__chan_val));
> +}
> +
> +static int __ltc2983_chan_custom_sensor_assign(struct ltc2983_data *st,
> +					  struct ltc2983_custom_sensor *custom,
> +					  u32 *chan_val)
> +{
> +	u32 reg;
> +	u8 mult = custom->is_steinhart ? LTC2983_CUSTOM_STEINHART_ENTRY_SZ :
> +		LTC2983_CUSTOM_SENSOR_ENTRY_SZ;
> +	const struct device *dev = &st->spi->dev;
> +	/*
> +	 * custom->size holds the raw size of the table. However, when
> +	 * configuring the sensor channel, we must write the number of
> +	 * entries of the table minus 1. For steinhart sensors 0 is written
> +	 * since the size is constant!
> +	 */
> +	const u8 len = custom->is_steinhart ? 0 :
> +		(custom->size / LTC2983_CUSTOM_SENSOR_ENTRY_SZ) - 1;
> +	/*
> +	 * Check if the offset was assigned already. It should be for steinhart
> +	 * sensors. When coming from sleep, it should be assigned for all.
> +	 */
> +	if (custom->offset < 0) {
> +		/*
> +		 * This needs to be done again here because, from the moment
> +		 * when this test was done (successfully) for this custom
> +		 * sensor, a steinhart sensor might have been added changing
> +		 * custom_table_size...
> +		 */
> +		if (st->custom_table_size + custom->size >
> +		    (LTC2983_CUST_SENS_TBL_END_REG -
> +		     LTC2983_CUST_SENS_TBL_START_REG) + 1) {
> +			dev_err(dev,
> +				"Not space left(%d) for new custom sensor(%zu)",
> +							st->custom_table_size,
> +							custom->size);
> +			return -EINVAL;
> +		}
> +
> +		custom->offset = st->custom_table_size /
> +					LTC2983_CUSTOM_SENSOR_ENTRY_SZ;
> +		st->custom_table_size += custom->size;
> +	}
> +
> +	reg = (custom->offset * mult) + LTC2983_CUST_SENS_TBL_START_REG;
> +
> +	*chan_val |= LTC2983_CUSTOM_LEN(len);
> +	*chan_val |= LTC2983_CUSTOM_ADDR(custom->offset);
> +	dev_dbg(dev, "Assign custom sensor, reg:0x%04X, off:%d, sz:%zu",
> +							reg, custom->offset,
> +							custom->size);
> +	/* write custom sensor table */
> +	return regmap_bulk_write(st->regmap, reg, custom->table, custom->size);
> +}
> +
> +static struct ltc2983_custom_sensor *__ltc2983_custom_sensor_new(
> +						struct ltc2983_data *st,
> +						const struct device_node *np,
> +						const bool is_steinhart,
> +						const u32 resolution,
> +						const bool has_signed)
> +{
> +	struct ltc2983_custom_sensor *new_custom;
> +	u8 index, n_entries, tbl = 0;
> +	struct device *dev = &st->spi->dev;
> +	/*
> +	 * For custom steinhart, the full u32 is taken. For all the others
> +	 * the MSB is discarded.
> +	 */
> +	const u8 n_size = (is_steinhart == true) ? 4 : 3;
> +
> +	n_entries = of_property_count_elems_of_size(np, "adi,custom-sensor",
> +						sizeof(u64));
> +	/* n_entries must be an even number */
> +	if (!n_entries || (n_entries % 2) != 0) {
> +		dev_err(dev, "Number of entries either 0 or not even\n");
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	new_custom = devm_kzalloc(dev, sizeof(*new_custom), GFP_KERNEL);
> +	if (!new_custom)
> +		return ERR_PTR(-ENOMEM);
> +
> +	new_custom->size = n_entries * n_size;
> +	/* check Steinhart size */
> +	if (is_steinhart && new_custom->size != LTC2983_CUSTOM_STEINHART_SIZE) {
> +		dev_err(dev, "Steinhart sensors size(%zu) must be 24",
> +							new_custom->size);
> +		return ERR_PTR(-EINVAL);
> +	}
> +	/* Check space on the table. */
> +	if (st->custom_table_size + new_custom->size >
> +	    (LTC2983_CUST_SENS_TBL_END_REG -
> +	     LTC2983_CUST_SENS_TBL_START_REG) + 1) {
> +		dev_err(dev, "No space left(%d) for new custom sensor(%zu)",
> +				st->custom_table_size, new_custom->size);
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	/* allocate the table */
> +	new_custom->table = devm_kzalloc(dev, new_custom->size, GFP_KERNEL);
> +	if (!new_custom->table)
> +		return ERR_PTR(-ENOMEM);
> +
> +	for (index = 0; index < n_entries; index++) {
> +		u64 temp = 0, j;
> +
> +		of_property_read_u64_index(np, "adi,custom-sensor", index,
> +					   &temp);
> +		/*
> +		 * Steinhart sensors are configured with raw values in the
> +		 * devicetree. For the other sensors we must convert the
> +		 * value to raw. The odd index's correspond to temperarures
> +		 * and always have 1/1024 of resolution. Temperatures also
> +		 * come in kelvin, so signed values is not possible
> +		 */
> +		if (!is_steinhart) {
> +			if ((index % 2) != 0)
> +				temp = __convert_to_raw(temp, 1024);
> +			else if (has_signed && (s64)temp < 0)
> +				temp = __convert_to_raw_sign(temp, resolution);
> +			else
> +				temp = __convert_to_raw(temp, resolution);
> +		}
> +
> +		for (j = 0; j < n_size; j++)
> +			new_custom->table[tbl++] =
> +				temp >> (8 * (n_size - j - 1));
> +	}
> +
> +	new_custom->is_steinhart = is_steinhart;
> +	/*
> +	 * This is done to first add all the steinhart sensors to the table,
> +	 * in order to maximize the table usage. If we mix adding steinhart
> +	 * with the other sensors, we might have to do some roundup to make
> +	 * sure that sensor_addr - 0x250(start address) is a multiple of 4
> +	 * (for steinhart), and a multiple of 6 for all the other sensors.
> +	 * Since we have const 24 bytes for steinhart sensors and 24 is
> +	 * also a multiple of 6, we guarantee that the first non-steinhart
> +	 * sensor will sit in a correct address without the need of filling
> +	 * addresses.
> +	 */
> +	if (is_steinhart) {
> +		new_custom->offset = st->custom_table_size /
> +					LTC2983_CUSTOM_STEINHART_ENTRY_SZ;
> +		st->custom_table_size += new_custom->size;
> +	} else {
> +		/* mark as unset. This is checked later on the assign phase */
> +		new_custom->offset = -1;
> +	}
> +
> +	return new_custom;
> +}
> +
> +static int ltc2983_thermocouple_fault_handler(const struct ltc2983_data *st,
> +					      const u32 result)
> +{
> +	return __ltc2983_fault_handler(st, result,
> +				       LTC2983_THERMOCOUPLE_HARD_FAULT_MASK,
> +				       LTC2983_THERMOCOUPLE_SOFT_FAULT_MASK);
> +}
> +
> +static int ltc2983_common_fault_handler(const struct ltc2983_data *st,
> +					const u32 result)
> +{
> +	return __ltc2983_fault_handler(st, result,
> +				       LTC2983_COMMON_HARD_FAULT_MASK,
> +				       LTC2983_COMMON_SOFT_FAULT_MASK);
> +}
> +
> +static int ltc2983_thermocouple_assign_chan(struct ltc2983_data *st,
> +				const struct ltc2983_sensor *sensor)
> +{
> +	struct ltc2983_thermocouple *thermo = to_thermocouple(sensor);
> +	u32 chan_val;
> +
> +	chan_val = LTC2983_CHAN_ASSIGN(thermo->cold_junction_chan);
> +	chan_val |= LTC2983_THERMOCOUPLE_CFG(thermo->sensor_config);
> +
> +	if (thermo->custom) {
> +		int ret;
> +
> +		ret = __ltc2983_chan_custom_sensor_assign(st, thermo->custom,
> +							  &chan_val);
> +		if (ret)
> +			return ret;
> +	}
> +	return __ltc2983_chan_assign_common(st, sensor, chan_val);
> +}
> +
> +static int ltc2983_rtd_assign_chan(struct ltc2983_data *st,
> +				   const struct ltc2983_sensor *sensor)
> +{
> +	struct ltc2983_rtd *rtd = to_rtd(sensor);
> +	u32 chan_val;
> +
> +	chan_val = LTC2983_CHAN_ASSIGN(rtd->r_sense_chan);
> +	chan_val |= LTC2983_RTD_CFG(rtd->sensor_config);
> +	chan_val |= LTC2983_RTD_EXC_CURRENT(rtd->excitation_current);
> +	chan_val |= LTC2983_RTD_CURVE(rtd->rtd_curve);
> +
> +	if (rtd->custom) {
> +		int ret;
> +
> +		ret = __ltc2983_chan_custom_sensor_assign(st, rtd->custom,
> +							  &chan_val);
> +		if (ret)
> +			return ret;
> +	}
> +	return __ltc2983_chan_assign_common(st, sensor, chan_val);
> +}
> +
> +static int ltc2983_thermistor_assign_chan(struct ltc2983_data *st,
> +					  const struct ltc2983_sensor *sensor)
> +{
> +	struct ltc2983_thermistor *thermistor = to_thermistor(sensor);
> +	u32 chan_val;
> +
> +	chan_val = LTC2983_CHAN_ASSIGN(thermistor->r_sense_chan);
> +	chan_val |= LTC2983_THERMISTOR_CFG(thermistor->sensor_config);
> +	chan_val |=
> +		LTC2983_THERMISTOR_EXC_CURRENT(thermistor->excitation_current);
> +
> +	if (thermistor->custom) {
> +		int ret;
> +
> +		ret = __ltc2983_chan_custom_sensor_assign(st,
> +							  thermistor->custom,
> +							  &chan_val);
> +		if (ret)
> +			return ret;
> +	}
> +	return __ltc2983_chan_assign_common(st, sensor, chan_val);
> +}
> +
> +static int ltc2983_diode_assign_chan(struct ltc2983_data *st,
> +				     const struct ltc2983_sensor *sensor)
> +{
> +	struct ltc2983_diode *diode = to_diode(sensor);
> +	u32 chan_val;
> +
> +	chan_val = LTC2983_DIODE_CFG(diode->sensor_config);
> +	chan_val |= LTC2983_DIODE_EXC_CURRENT(diode->excitation_current);
> +	chan_val |= LTC2983_DIODE_IDEAL_FACTOR(diode->ideal_factor_value);
> +
> +	return __ltc2983_chan_assign_common(st, sensor, chan_val);
> +}
> +
> +static int ltc2983_r_sense_assign_chan(struct ltc2983_data *st,
> +				       const struct ltc2983_sensor *sensor)
> +{
> +	struct ltc2983_rsense *rsense = to_rsense(sensor);
> +	u32 chan_val;
> +
> +	chan_val = LTC2983_R_SENSE_VAL(rsense->r_sense_val);
> +
> +	return __ltc2983_chan_assign_common(st, sensor, chan_val);
> +}
> +
> +static int ltc2983_adc_assign_chan(struct ltc2983_data *st,
> +				   const struct ltc2983_sensor *sensor)
> +{
> +	struct ltc2983_adc *adc = to_adc(sensor);
> +	u32 chan_val;
> +
> +	chan_val = LTC2983_ADC_SINGLE_ENDED(adc->single_ended);
> +
> +	return __ltc2983_chan_assign_common(st, sensor, chan_val);
> +}
> +
> +static struct ltc2983_sensor *ltc2983_thermocouple_new(
> +					const struct device_node *child,
> +					struct ltc2983_data *st,
> +					const struct ltc2983_sensor *sensor)
> +{
> +	struct ltc2983_thermocouple *thermo;
> +	struct device_node *phandle;
> +
> +	thermo = devm_kzalloc(&st->spi->dev, sizeof(*thermo), GFP_KERNEL);
> +	if (!thermo)
> +		return ERR_PTR(-ENOMEM);
> +
> +	of_property_read_u32(child, "adi,sensor-config",
> +				 &thermo->sensor_config);
> +	/* validate channel index */
> +	if (!(thermo->sensor_config & LTC2983_THERMOCOUPLE_DIFF_MASK) &&
> +	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
> +		dev_err(&st->spi->dev,
> +			"Invalid chann:%d for differential thermocouple",
> +								sensor->chan);
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	phandle = of_parse_phandle(child, "adi,cold-junction-handle", 0);
> +	if (phandle) {
> +		int ret;
> +
> +		ret = of_property_read_u32(phandle, "reg",
> +					   &thermo->cold_junction_chan);
> +		if (ret) {
> +			/*
> +			 * This would be catched later but we can just return
> +			 * the error right away.
> +			 */
> +			dev_err(&st->spi->dev, "Property reg must be given\n");
> +			of_node_put(phandle);
> +			return ERR_PTR(-EINVAL);
> +		}
> +	}
> +
> +	/* check custom sensor */
> +	if (sensor->type == LTC2983_SENSOR_THERMOCOUPLE_CUSTOM) {
> +		thermo->custom = __ltc2983_custom_sensor_new(st, child, false,
> +							     16384, true);
> +		if (IS_ERR(thermo->custom)) {
> +			of_node_put(phandle);
> +			return ERR_CAST(thermo->custom);
> +		}
> +	}
> +
> +	/* set common parameters */
> +	thermo->sensor.fault_handler = ltc2983_thermocouple_fault_handler;
> +	thermo->sensor.assign_chan = ltc2983_thermocouple_assign_chan;
> +
> +	of_node_put(phandle);
> +	return &thermo->sensor;
> +}
> +
> +static struct ltc2983_sensor *ltc2983_rtd_new(const struct device_node *child,
> +					  struct ltc2983_data *st,
> +					  const struct ltc2983_sensor *sensor)
> +{
> +	struct ltc2983_rtd *rtd;
> +	int ret = 0;
> +	struct device *dev = &st->spi->dev;
> +	struct device_node *phandle;
> +	u32 excitation_current = 0;
> +
> +	rtd = devm_kzalloc(dev, sizeof(*rtd), GFP_KERNEL);
> +	if (!rtd)
> +		return ERR_PTR(-ENOMEM);
> +
> +	phandle = of_parse_phandle(child, "adi,rsense-handle", 0);
> +	if (!phandle) {
> +		dev_err(dev, "Property adi,rsense-handle missing or invalid");
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	ret = of_property_read_u32(phandle, "reg", &rtd->r_sense_chan);
> +	if (ret) {
> +		dev_err(dev, "Property reg must be given\n");
> +		goto fail;
> +	}
> +
> +	of_property_read_u32(child, "adi,sensor-config", &rtd->sensor_config);
> +	/*
> +	 * rtd channel indexes are a bit more complicated to validate.
> +	 * For 4wire RTD with rotation, the channel selection cannot be
> +	 * >=19 since the chann + 1 is used in this configuration.
> +	 * For 4wire RTDs with kelvin rsense, the rsense channel cannot be
> +	 * <=1 since chanel - 1 and channel - 2 are used.
> +	 */
> +	if (rtd->sensor_config & LTC2983_RTD_4_WIRE_MASK) {
> +		/* 4-wire */
> +		u8 min = LTC2983_DIFFERENTIAL_CHAN_MIN,
> +			max = LTC2983_MAX_CHANNELS_NR;
> +
> +		if (rtd->sensor_config & LTC2983_RTD_ROTATION_MASK)
> +			max = LTC2983_MAX_CHANNELS_NR - 1;
> +
> +		if (((rtd->sensor_config & LTC2983_RTD_KELVIN_R_SENSE_MASK)
> +		     == LTC2983_RTD_KELVIN_R_SENSE_MASK) &&
> +		    (rtd->r_sense_chan <=  min)) {
> +			/* kelvin rsense*/
> +			dev_err(dev,
> +				"Invalid rsense chann:%d to use in kelvin rsense",
> +							rtd->r_sense_chan);
> +
> +			ret = -EINVAL;
> +			goto fail;
> +		}
> +
> +		if (sensor->chan < min || sensor->chan > max) {
> +			dev_err(dev, "Invalid chann:%d for the rtd config",
> +								sensor->chan);
> +
> +			ret = -EINVAL;
> +			goto fail;
> +		}
> +	} else {
> +		/* same as differential case */
> +		if (sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
> +			dev_err(&st->spi->dev,
> +				"Invalid chann:%d for RTD", sensor->chan);
> +
> +			ret = -EINVAL;
> +			goto fail;
> +		}
> +	}
> +
> +	/* check custom sensor */
> +	if (sensor->type == LTC2983_SENSOR_RTD_CUSTOM) {
> +		rtd->custom = __ltc2983_custom_sensor_new(st, child, false,
> +							  2048, false);
> +		if (IS_ERR(rtd->custom)) {
> +			of_node_put(phandle);
> +			return ERR_CAST(rtd->custom);
> +		}
> +	}
> +
> +	/* set common parameters */
> +	rtd->sensor.fault_handler = ltc2983_common_fault_handler;
> +	rtd->sensor.assign_chan = ltc2983_rtd_assign_chan;
> +
> +	ret = of_property_read_u32(child, "adi,excitation-current-microamp",
> +				   &excitation_current);
> +	if (ret) {
> +		/* default to 5uA */
> +		rtd->excitation_current = 1;
> +	} else {
> +		switch (excitation_current) {
> +		case 5:
> +			rtd->excitation_current = 0x01;
> +			break;
> +		case 10:
> +			rtd->excitation_current = 0x02;
> +			break;
> +		case 25:
> +			rtd->excitation_current = 0x03;
> +			break;
> +		case 50:
> +			rtd->excitation_current = 0x04;
> +			break;
> +		case 100:
> +			rtd->excitation_current = 0x05;
> +			break;
> +		case 250:
> +			rtd->excitation_current = 0x06;
> +			break;
> +		case 500:
> +			rtd->excitation_current = 0x07;
> +			break;
> +		case 1000:
> +			rtd->excitation_current = 0x08;
> +			break;
> +		default:
> +			dev_err(&st->spi->dev,
> +				"Invalid value for excitation current(%u)",
> +							excitation_current);
> +			ret = -EINVAL;
> +			goto fail;
> +		}
> +	}
> +
> +	of_property_read_u32(child, "adi,rtd-curve", &rtd->rtd_curve);
> +
> +	of_node_put(phandle);
> +	return &rtd->sensor;
> +fail:
> +	of_node_put(phandle);
> +	return ERR_PTR(ret);
> +}
> +
> +static struct ltc2983_sensor *ltc2983_thermistor_new(
> +					const struct device_node *child,
> +					struct ltc2983_data *st,
> +					const struct ltc2983_sensor *sensor)
> +{
> +	struct ltc2983_thermistor *thermistor;
> +	struct device *dev = &st->spi->dev;
> +	struct device_node *phandle;
> +	u32 excitation_current = 0;
> +	int ret = 0;
> +
> +	thermistor = devm_kzalloc(dev, sizeof(*thermistor), GFP_KERNEL);
> +	if (!thermistor)
> +		return ERR_PTR(-ENOMEM);
> +
> +	phandle = of_parse_phandle(child, "adi,rsense-handle", 0);
> +	if (!phandle) {
> +		dev_err(dev, "Property adi,rsense-handle missing or invalid");
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	ret = of_property_read_u32(phandle, "reg", &thermistor->r_sense_chan);
> +	if (ret) {
> +		dev_err(dev, "rsense channel must be configured...\n");
> +		goto fail;
> +	}
> +
> +	of_property_read_u32(child, "adi,sensor-config",
> +			     &thermistor->sensor_config);
> +	/* validate channel index */
> +	if (!(thermistor->sensor_config & LTC2983_THERMISTOR_DIFF_MASK) &&
> +	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
> +		dev_err(&st->spi->dev,
> +			"Invalid chann:%d for differential thermistor",
> +								sensor->chan);
> +		ret = -EINVAL;
> +		goto fail;
> +	}
> +
> +	/* check custom sensor */
> +	if (sensor->type >= LTC2983_SENSOR_THERMISTOR_STEINHART) {
> +		thermistor->custom = __ltc2983_custom_sensor_new(st, child,
> +			sensor->type == LTC2983_SENSOR_THERMISTOR_STEINHART ?
> +							  true : false, 64,
> +							  false);
> +		if (IS_ERR(thermistor->custom)) {
> +			of_node_put(phandle);
> +			return ERR_CAST(thermistor->custom);
> +		}
> +	}
> +	/* set common parameters */
> +	thermistor->sensor.fault_handler = ltc2983_common_fault_handler;
> +	thermistor->sensor.assign_chan = ltc2983_thermistor_assign_chan;
> +
> +	ret = of_property_read_u32(child, "adi,excitation-current-nanoamp",
> +				   &excitation_current);
> +	if (ret) {
> +		/* Auto range is not allowed for custom sensors */
> +		if (sensor->type >= LTC2983_SENSOR_THERMISTOR_STEINHART)
> +			/* default to 1uA */
> +			thermistor->excitation_current = 0x03;
> +		else
> +			/* default to auto-range */
> +			thermistor->excitation_current = 0x0c;
> +	} else {
> +		switch (excitation_current) {
> +		case 0:
> +			/* auto range */
> +			if (sensor->type >=
> +			    LTC2983_SENSOR_THERMISTOR_STEINHART) {
> +				dev_err(&st->spi->dev,
> +					"Auto Range not allowed for custom sensors\n");
> +				ret = -EINVAL;
> +				goto fail;
> +			}
> +			thermistor->excitation_current = 0x0c;
> +			break;
> +		case 250:
> +			thermistor->excitation_current = 0x01;
> +			break;
> +		case 500:
> +			thermistor->excitation_current = 0x02;
> +			break;
> +		case 1000:
> +			thermistor->excitation_current = 0x03;
> +			break;
> +		case 5000:
> +			thermistor->excitation_current = 0x04;
> +			break;
> +		case 10000:
> +			thermistor->excitation_current = 0x05;
> +			break;
> +		case 25000:
> +			thermistor->excitation_current = 0x06;
> +			break;
> +		case 50000:
> +			thermistor->excitation_current = 0x07;
> +			break;
> +		case 100000:
> +			thermistor->excitation_current = 0x08;
> +			break;
> +		case 250000:
> +			thermistor->excitation_current = 0x09;
> +			break;
> +		case 500000:
> +			thermistor->excitation_current = 0x0a;
> +			break;
> +		case 1000000:
> +			thermistor->excitation_current = 0x0b;
> +			break;
> +		default:
> +			dev_err(&st->spi->dev,
> +				"Invalid value for excitation current(%u)",
> +							excitation_current);
> +			ret = -EINVAL;
> +			goto fail;
> +		}
> +	}
> +
> +	of_node_put(phandle);
> +	return &thermistor->sensor;
> +fail:
> +	of_node_put(phandle);
> +	return ERR_PTR(ret);
> +}
> +
> +static struct ltc2983_sensor *ltc2983_diode_new(
> +					const struct device_node *child,
> +					const struct ltc2983_data *st,
> +					const struct ltc2983_sensor *sensor)
> +{
> +	struct ltc2983_diode *diode;
> +	u32 temp = 0, excitation_current = 0;
> +	int ret;
> +
> +	diode = devm_kzalloc(&st->spi->dev, sizeof(*diode), GFP_KERNEL);
> +	if (!diode)
> +		return ERR_PTR(-ENOMEM);
> +
> +	of_property_read_u32(child, "adi,sensor-config", &diode->sensor_config);
> +	/* validate channel index */
> +	if (!(diode->sensor_config & LTC2983_DIODE_DIFF_MASK) &&
> +	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
> +		dev_err(&st->spi->dev,
> +			"Invalid chann:%d for differential thermistor",
> +								sensor->chan);
> +		return ERR_PTR(-EINVAL);
> +	}
> +	/* set common parameters */
> +	diode->sensor.fault_handler = ltc2983_common_fault_handler;
> +	diode->sensor.assign_chan = ltc2983_diode_assign_chan;
> +
> +	ret = of_property_read_u32(child, "adi,excitation-current-microamp",
> +				   &excitation_current);
> +	if (!ret) {
> +		switch (excitation_current) {
> +		case 10:
> +			diode->excitation_current = 0x00;
> +			break;
> +		case 20:
> +			diode->excitation_current = 0x01;
> +			break;
> +		case 40:
> +			diode->excitation_current = 0x02;
> +			break;
> +		case 80:
> +			diode->excitation_current = 0x03;
> +			break;
> +		default:
> +			dev_err(&st->spi->dev,
> +				"Invalid value for excitation current(%u)",
> +							excitation_current);
> +			return ERR_PTR(-EINVAL);
> +		}
> +	}
> +
> +	of_property_read_u32(child, "adi,ideal-factor-value", &temp);
> +
> +	/* 2^20 resolution */
> +	diode->ideal_factor_value = __convert_to_raw(temp, 1048576);
> +
> +	return &diode->sensor;
> +}
> +
> +static struct ltc2983_sensor *ltc2983_r_sense_new(struct device_node *child,
> +					struct ltc2983_data *st,
> +					const struct ltc2983_sensor *sensor)
> +{
> +	struct ltc2983_rsense *rsense;
> +	int ret;
> +	u64 temp;
> +
> +	rsense = devm_kzalloc(&st->spi->dev, sizeof(*rsense), GFP_KERNEL);
> +	if (!rsense)
> +		return ERR_PTR(-ENOMEM);
> +
> +	/* validate channel index */
> +	if (sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
> +		dev_err(&st->spi->dev, "Invalid chann:%d for r_sense",
> +							sensor->chan);
> +		return ERR_PTR(-EINVAL);
> +	}
> +	/* get raw value */
> +	ret = of_property_read_u64(child, "adi,rsense-val-micro-ohms", &temp);
> +	if (ret) {
> +		dev_err(&st->spi->dev, "Property adi,rsense-val-micro-ohms missing\n");
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	/* 2^10 resolution */
> +	rsense->r_sense_val = __convert_to_raw(temp, 1024);
> +
> +	/* set common parameters */
> +	rsense->sensor.assign_chan = ltc2983_r_sense_assign_chan;
> +
> +	return &rsense->sensor;
> +}
> +
> +static struct ltc2983_sensor *ltc2983_adc_new(struct device_node *child,
> +					 struct ltc2983_data *st,
> +					 const struct ltc2983_sensor *sensor)
> +{
> +	struct ltc2983_adc *adc;
> +
> +	adc = devm_kzalloc(&st->spi->dev, sizeof(*adc), GFP_KERNEL);
> +	if (!adc)
> +		return ERR_PTR(-ENOMEM);
> +
> +	if (of_property_read_bool(child, "adi,single-ended"))
> +		adc->single_ended = true;
> +
> +	if (!adc->single_ended &&
> +	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
> +		dev_err(&st->spi->dev, "Invalid chan:%d for differential adc\n",
> +								sensor->chan);
> +		return ERR_PTR(-EINVAL);
> +	}
> +	/* set common parameters */
> +	adc->sensor.assign_chan = ltc2983_adc_assign_chan;
> +	adc->sensor.fault_handler = ltc2983_common_fault_handler;
> +
> +	return &adc->sensor;
> +}
> +
> +static int ltc2983_chan_read(struct ltc2983_data *st,
> +			const struct ltc2983_sensor *sensor, int *val)
> +{
> +	u32 start_conversion = 0;
> +	int ret;
> +	unsigned long time;
> +	__be32 temp;
> +
> +	/*
> +	 * Do not allow channel readings if device is in sleep state.
> +	 * A read/write on the spi bus would bring the device prematurely
> +	 * out of sleep.
> +	 */
> +	if (st->sleep)
> +		return -EPERM;
> +
> +	start_conversion = LTC2983_STATUS_START(true);
> +	start_conversion |= LTC2983_STATUS_CHAN_SEL(sensor->chan);
> +	dev_dbg(&st->spi->dev, "Start conversion on chan:%d, status:%02X\n",
> +		sensor->chan, start_conversion);
> +	/* start conversion */
> +	ret = regmap_write(st->regmap, LTC2983_STATUS_REG, start_conversion);
> +	if (ret)
> +		return ret;
> +
> +	reinit_completion(&st->completion);
> +	/*
> +	 * wait for conversion to complete.
> +	 * 300 ms should be more than enough to complete the conversion.
> +	 * Depending on the sensor configuration, there are 2/3 conversions
> +	 * cycles of 82ms.
> +	 */
> +	time = wait_for_completion_timeout(&st->completion,
> +					   msecs_to_jiffies(300));
> +	if (!time) {
> +		dev_warn(&st->spi->dev, "Conversion timed out\n");
> +		return -ETIMEDOUT;
> +	}
> +
> +	/* read the converted data */
> +	ret = regmap_bulk_read(st->regmap, LTC2983_CHAN_RES_ADDR(sensor->chan),
> +			       &temp, sizeof(temp));
> +	if (ret)
> +		return ret;
> +
> +	*val = __be32_to_cpu(temp);
> +
> +	if (!(LTC2983_RES_VALID_MASK & *val)) {
> +		dev_err(&st->spi->dev, "Invalid conversion detected\n");
> +		return -EIO;
> +	}
> +
> +	ret = sensor->fault_handler(st, *val);
> +	if (ret)
> +		return ret;
> +
> +	*val = sign_extend32((*val) & LTC2983_DATA_MASK, LTC2983_DATA_SIGN_BIT);
> +	return 0;
> +}
> +
> +static int ltc2983_read_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int *val, int *val2, long mask)
> +{
> +	struct ltc2983_data *st = iio_priv(indio_dev);
> +	int ret;
> +
> +	/* sanity check */
> +	if (chan->address >= st->num_channels) {
> +		dev_err(&st->spi->dev, "Invalid chan address:%ld",
> +							chan->address);
> +		return -EINVAL;
> +	}
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		mutex_lock(&st->lock);
> +		ret = ltc2983_chan_read(st, st->sensors[chan->address], val);
> +		mutex_unlock(&st->lock);
> +		return ret ?: IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (chan->type) {
> +		case IIO_TEMP:
> +			/* value in milli degrees */
> +			*val = 1000;
> +			/* 2^10 */
> +			*val2 = 1024;
> +			return IIO_VAL_FRACTIONAL;
> +		case IIO_VOLTAGE:
> +			/* value in millivolt */
> +			*val = 1000;
> +			/* 2^21 */
> +			*val2 = 2097152;
> +			return IIO_VAL_FRACTIONAL;
> +		default:
> +			return -EINVAL;
> +		}
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int ltc2983_reg_access(struct iio_dev *indio_dev,
> +			      unsigned int reg,
> +			      unsigned int writeval,
> +			      unsigned int *readval)
> +{
> +	struct ltc2983_data *st = iio_priv(indio_dev);
> +
> +	/* check comment in ltc2983_chan_read() */
> +	if (st->sleep)
> +		return -EPERM;
> +
> +	if (readval)
> +		return regmap_read(st->regmap, reg, readval);
> +	else
> +		return regmap_write(st->regmap, reg, writeval);
> +}
> +
> +static irqreturn_t ltc2983_irq_handler(int irq, void *data)
> +{
> +	struct ltc2983_data *st = data;
> +
> +	complete(&st->completion);

This is a rare case where I'm not sure a threaded irq actually
makes sense.  We may be better off just doing this in a traditional
top half, rather than spinning up a thread just to set completion.

> +	return IRQ_HANDLED;
> +}
> +
> +#define LTC2983_CHAN(__type, index, __address) ({ \
> +	struct iio_chan_spec __chan = { \
> +		.type = __type, \
> +		.indexed = 1, \
> +		.channel = index, \
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> +		.address = __address, \
> +	}; \
> +	__chan; \
> +})
> +
> +static int ltc2983_parse_dt(struct ltc2983_data *st)
> +{
> +	struct device_node *child;
> +	struct device *dev = &st->spi->dev;
> +	int ret = 0, chan = 0, channel_avail_mask = 0;
> +
> +	if (!of_property_read_bool(dev->of_node, "adi,temperature-celcius"))
> +		st->temp_farenheit = true;
> +
> +	of_property_read_u32(dev->of_node, "adi,mux-delay-config-us",
> +			     &st->mux_delay_config);
> +
> +	of_property_read_u32(dev->of_node, "adi,filter-notch-freq",
> +			     &st->filter_notch_freq);
> +
> +	st->num_channels = of_get_available_child_count(dev->of_node);
> +	st->sensors = devm_kcalloc(dev, st->num_channels, sizeof(*st->sensors),
> +				   GFP_KERNEL);
> +	if (!st->sensors)
> +		return -ENOMEM;
> +
> +	st->iio_channels = st->num_channels;
> +	for_each_available_child_of_node(dev->of_node, child) {
> +		struct ltc2983_sensor sensor;
> +
> +		ret = of_property_read_u32(child, "reg", &sensor.chan);
> +		if (ret) {
> +			dev_err(dev, "reg property must given for child nodes\n");
> +			return ret;
> +		}
> +
> +		/* check if we have a valid channel */
> +		if (sensor.chan < LTC2983_MIN_CHANNELS_NR ||
> +		    sensor.chan > LTC2983_MAX_CHANNELS_NR) {
> +			dev_err(dev,
> +				"chan:%d must be from 1 to 20\n", sensor.chan);
> +			return -EINVAL;
> +		} else if (channel_avail_mask & BIT(sensor.chan)) {
> +			dev_err(dev, "chan:%d already in use\n", sensor.chan);
> +			return -EINVAL;
> +		}
> +
> +		ret = of_property_read_u32(child, "adi,sensor-type",
> +					       &sensor.type);
> +		if (ret) {
> +			dev_err(dev,
> +				"adi,sensor-type property must given for child nodes\n");
> +			return ret;
> +		}
> +
> +		dev_dbg(dev, "Create new sensor, type %u, chann %u",
> +								sensor.type,
> +								sensor.chan);
> +
> +		if (sensor.type >= LTC2983_SENSOR_THERMOCOUPLE &&
> +		    sensor.type <= LTC2983_SENSOR_THERMOCOUPLE_CUSTOM) {
> +			st->sensors[chan] = ltc2983_thermocouple_new(child, st,
> +								     &sensor);
> +		} else if (sensor.type >= LTC2983_SENSOR_RTD &&
> +			   sensor.type <= LTC2983_SENSOR_RTD_CUSTOM) {
> +			st->sensors[chan] = ltc2983_rtd_new(child, st, &sensor);
> +		} else if (sensor.type >= LTC2983_SENSOR_THERMISTOR &&
> +			   sensor.type <= LTC2983_SENSOR_THERMISTOR_CUSTOM) {
> +			st->sensors[chan] = ltc2983_thermistor_new(child, st,
> +								   &sensor);
> +		} else if (sensor.type == LTC2983_SENSOR_DIODE) {
> +			st->sensors[chan] = ltc2983_diode_new(child, st,
> +							      &sensor);
> +		} else if (sensor.type == LTC2983_SENSOR_SENSE_RESISTOR) {
> +			st->sensors[chan] = ltc2983_r_sense_new(child, st,
> +								&sensor);
> +			/* don't add rsense to iio */
> +			st->iio_channels--;
> +		} else if (sensor.type == LTC2983_SENSOR_DIRECT_ADC) {
> +			st->sensors[chan] = ltc2983_adc_new(child, st, &sensor);
> +		} else {
> +			dev_err(dev, "Unknown sensor type %d\n", sensor.type);
> +			return -EINVAL;
> +		}
> +
> +		if (IS_ERR(st->sensors[chan])) {
> +			dev_err(dev, "Failed to create sensor %ld",
> +						PTR_ERR(st->sensors[chan]));
> +			return PTR_ERR(st->sensors[chan]);
> +		}
> +		/* set generic sensor parameters */
> +		st->sensors[chan]->chan = sensor.chan;
> +		st->sensors[chan]->type = sensor.type;
> +
> +		channel_avail_mask |= BIT(sensor.chan);
> +		chan++;
> +	}
> +
> +	return 0;
> +}
> +
> +static int ltc2983_setup(struct ltc2983_data *st, bool assign_iio)
> +{
> +	u32 iio_chan_t = 0, iio_chan_v = 0, chan, iio_idx = 0;
> +	u32 global_cfg = 0;
> +	int ret;
> +	unsigned long time;
> +
> +	/* make sure the device is up */
> +	time = wait_for_completion_timeout(&st->completion,
> +					    msecs_to_jiffies(250));
> +
> +	if (!time) {
> +		dev_err(&st->spi->dev, "Device startup timed out\n");
> +		return -ETIMEDOUT;
> +	}
> +
> +	st->iio_chan = devm_kzalloc(&st->spi->dev,
> +				    st->iio_channels * sizeof(*st->iio_chan),
> +				    GFP_KERNEL);
> +
> +	if (!st->iio_chan)
> +		return -ENOMEM;
> +
> +	global_cfg = LTC2983_NOTCH_FREQ(st->filter_notch_freq);
> +	global_cfg |= LTC2983_TEMP_UNITS(st->temp_farenheit);
> +	regmap_write(st->regmap, LTC2983_GLOBAL_CONFIG_REG, global_cfg);
> +	regmap_write(st->regmap, LTC2983_MUX_CONFIG_REG, st->mux_delay_config);
> +
> +	for (chan = 0; chan < st->num_channels; chan++) {
> +		u32 chan_type = 0, *iio_chan;
> +
> +		ret = st->sensors[chan]->assign_chan(st, st->sensors[chan]);
> +		if (ret)
> +			return ret;
> +		/*
> +		 * The assign_iio flag is necessary for when the device is
> +		 * coming out of sleep. In that case, we just need to
> +		 * re-configure the device channels.
> +		 * We also don't assign iio channels for rsense.
> +		 */
> +		if (st->sensors[chan]->type == LTC2983_SENSOR_SENSE_RESISTOR ||
> +		    !assign_iio)
> +			continue;
> +
> +		/* assign iio channel */
> +		if (st->sensors[chan]->type != LTC2983_SENSOR_DIRECT_ADC) {
> +			chan_type = IIO_TEMP;
> +			iio_chan = &iio_chan_t;
> +		} else {
> +			chan_type = IIO_VOLTAGE;
> +			iio_chan = &iio_chan_v;
> +		}
> +
> +		/*
> +		 * add chan as the iio .address so that, we can directly
> +		 * reference the sensor given the iio_chan_spec
> +		 */
> +		st->iio_chan[iio_idx++] = LTC2983_CHAN(chan_type, (*iio_chan)++,
> +						       chan);
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct regmap_range ltc2983_reg_ranges[] = {
> +	regmap_reg_range(LTC2983_STATUS_REG, LTC2983_STATUS_REG),
> +	regmap_reg_range(LTC2983_TEMP_RES_START_REG, LTC2983_TEMP_RES_END_REG),
> +	regmap_reg_range(LTC2983_GLOBAL_CONFIG_REG, LTC2983_GLOBAL_CONFIG_REG),
> +	regmap_reg_range(LTC2983_MULT_CHANNEL_START_REG,
> +			 LTC2983_MULT_CHANNEL_END_REG),
> +	regmap_reg_range(LTC2983_MUX_CONFIG_REG, LTC2983_MUX_CONFIG_REG),
> +	regmap_reg_range(LTC2983_CHAN_ASSIGN_START_REG,
> +			 LTC2983_CHAN_ASSIGN_END_REG),
> +	regmap_reg_range(LTC2983_CUST_SENS_TBL_START_REG,
> +			 LTC2983_CUST_SENS_TBL_END_REG),
> +};
> +
> +static const struct regmap_access_table ltc2983_reg_table = {
> +	.yes_ranges = ltc2983_reg_ranges,
> +	.n_yes_ranges = ARRAY_SIZE(ltc2983_reg_ranges),
> +};
> +
> +/*
> + *  The reg_bits are actually 12 but the device needs the first *complete*
> + *  byte for the command (R/W).
> + */
> +static const struct regmap_config ltc2983_regmap_config = {
> +	.reg_bits = 24,
> +	.val_bits = 8,
> +	.wr_table = &ltc2983_reg_table,
> +	.rd_table = &ltc2983_reg_table,
> +	.read_flag_mask = GENMASK(1, 0),
> +	.write_flag_mask = BIT(1),
> +};
> +
> +static const struct  iio_info ltc2983_iio_info = {
> +	.read_raw = ltc2983_read_raw,
> +	.debugfs_reg_access = ltc2983_reg_access,
> +};
> +
> +static int ltc2983_probe(struct spi_device *spi)
> +{
> +	struct ltc2983_data *st;
> +	struct iio_dev *indio_dev;
> +	const char *name = spi_get_device_id(spi)->name;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	st = iio_priv(indio_dev);
> +
> +	st->regmap = devm_regmap_init_spi(spi, &ltc2983_regmap_config);
> +	if (IS_ERR(st->regmap)) {
> +		dev_err(&spi->dev, "Failed to initialize regmap\n");
> +		return PTR_ERR(st->regmap);
> +	}
> +
> +	mutex_init(&st->lock);
> +	init_completion(&st->completion);
> +	st->spi = spi;
> +	spi_set_drvdata(spi, st);
> +
> +	ret = ltc2983_parse_dt(st);
> +	if (ret)
> +		return ret;
> +	/*
> +	 * let's request the irq now so it is used to sync the device
> +	 * startup in ltc2983_setup()
> +	 */
> +	ret = devm_request_threaded_irq(&spi->dev, spi->irq, NULL,
> +					ltc2983_irq_handler, IRQF_ONESHOT |
> +					IRQF_TRIGGER_RISING, name, st);
> +	if (ret) {
> +		dev_err(&spi->dev, "failed to request an irq, %d", ret);
> +		return ret;
> +	}
> +
> +	ret = ltc2983_setup(st, true);
> +	if (ret)
> +		return ret;
> +
> +	indio_dev->dev.parent = &spi->dev;
> +	indio_dev->name = name;
> +	indio_dev->num_channels = st->iio_channels;
> +	indio_dev->channels = st->iio_chan;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->info = &ltc2983_iio_info;
> +
> +	return devm_iio_device_register(&spi->dev, indio_dev);
> +}
> +
> +static int __maybe_unused ltc2983_resume(struct device *dev)
> +{
> +	struct ltc2983_data *st = spi_get_drvdata(to_spi_device(dev));
> +	int ret;
> +
> +	mutex_lock(&st->lock);
> +	/* dummy read to bring the device out of sleep */
> +	regmap_read(st->regmap, LTC2983_STATUS_REG, &ret);
> +	/* we need to re-assign the channels */
> +	ret = ltc2983_setup(st, false);
> +	st->sleep = false;
> +	mutex_unlock(&st->lock);
> +
> +	return ret;
> +}
> +
> +static int __maybe_unused ltc2983_suspend(struct device *dev)
> +{
> +	struct ltc2983_data *st = spi_get_drvdata(to_spi_device(dev));
> +	int ret;
> +
> +	mutex_lock(&st->lock);
> +	ret = regmap_write(st->regmap, LTC2983_STATUS_REG, LTC2983_SLEEP);
> +	st->sleep = true;
> +	mutex_unlock(&st->lock);
> +
> +	return ret;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(ltc2983_pm_ops, ltc2983_suspend, ltc2983_resume);
> +
> +static const struct spi_device_id ltc2983_id_table[] = {
> +	{ "ltc2983" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(spi, ltc2983_id_table);
> +
> +static const struct of_device_id ltc2983_of_match[] = {
> +	{ .compatible = "adi,ltc2983" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, ltc2983_id_table);
> +
> +static struct spi_driver ltc2983_driver = {
> +	.driver = {
> +		.name = "ltc2983",
> +		.of_match_table = ltc2983_of_match,
> +		.pm = &ltc2983_pm_ops,
> +	},
> +	.probe = ltc2983_probe,
> +	.id_table = ltc2983_id_table,
> +};
> +
> +module_spi_driver(ltc2983_driver);
> +
> +MODULE_AUTHOR("Nuno Sa <[e-mail]>");
> +MODULE_DESCRIPTION("Analog Devices LTC2983 SPI Temperature sensors");
> +MODULE_LICENSE("GPL");

Nuno Sa Oct. 2, 2019, 12:07 p.m. UTC | #2

On Tue, 2019-10-01 at 10:03 +0100, Jonathan Cameron wrote:
> 
> On Mon, 30 Sep 2019 12:42:46 +0200
> Nuno Sá <[e-mail]> wrote:
> 
> > The LTC2983 is a Multi-Sensor High Accuracy Digital Temperature
> > Measurement System. It measures a wide variety of temperature
> > sensors and
> > digitally outputs the result, in °C or °F, with 0.1°C accuracy and
> > 0.001°C resolution. It can measure the temperature of all standard
> > thermocouples (type B,E,J,K,N,S,R,T), standard 2-,3-,4-wire RTDs,
> > thermistors and diodes.
> > 
> > Signed-off-by: Nuno Sá <[e-mail]>
> 
> One minor comment inline.  I don't see a reason to use a threaded irq
> to simply set a completion. Just do it with a traditional irq.
> I suspect the overhead of doing that is probably similar to spinning
> up the irq thread.

ack.

> Otherwise, I'm happy with this subject to binding review.
> 
> Thanks,
> 
> Jonathan
> 
> > ---
> > Changes in v2:
> >  * Added some needed blank lines (for readability);
> >  * Allocate iio_chan in the setup() function;
> >  * Rename reset to sleep;
> >  * Remove unneeded dev_dbg calls;
> >  * Remove unneeded line wrapping;
> >  * Remove unneeded comments;
> >  * Remove extend_names. Use the standard ABI;
> >  * Adapt the scales to report in millivolt and milli degrees;
> >  * Adapt the of_property readings to the renaming of the
> > properties;
> >  * For custom thermistors, excitation-current cannot be set to Auto
> > range.
> > 
> >  MAINTAINERS                       |    7 +
> >  drivers/iio/temperature/Kconfig   |   10 +
> >  drivers/iio/temperature/Makefile  |    1 +
> >  drivers/iio/temperature/ltc2983.c | 1436
> > +++++++++++++++++++++++++++++
> >  4 files changed, 1454 insertions(+)
> >  create mode 100644 drivers/iio/temperature/ltc2983.c
> > 
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index f0c03740b9fb..14a256e785ca 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -9491,6 +9491,13 @@ S:	Maintained
> >  F:	Documentation/devicetree/bindings/iio/dac/ltc1660.txt
> >  F:	drivers/iio/dac/ltc1660.c
> >  
> > +LTC2983 IIO TEMPERATURE DRIVER
> > +M:	Nuno Sá <[e-mail]>
> > +W:	http://ez.analog.com/community/linux-device-drivers
> > +L:	[e-mail]
> > +S:	Supported
> > +F:	drivers/iio/temperature/ltc2983.c
> > +
> >  LTC4261 HARDWARE MONITOR DRIVER
> >  M:	Guenter Roeck <[e-mail]>
> >  L:	[e-mail]
> > diff --git a/drivers/iio/temperature/Kconfig
> > b/drivers/iio/temperature/Kconfig
> > index 737faa0901fe..04b5a67b593c 100644
> > --- a/drivers/iio/temperature/Kconfig
> > +++ b/drivers/iio/temperature/Kconfig
> > @@ -4,6 +4,16 @@
> >  #
> >  menu "Temperature sensors"
> >  
> > +config LTC2983
> > +	tristate "Analog Devices Multi-Sensor Digital Temperature
> > Measurement System"
> > +	depends on SPI
> > +	help
> > +	  Say yes here to build support for the LTC2983 Multi-Sensor
> > +	  high accuracy digital temperature measurement system.
> > +
> > +	  To compile this driver as a module, choose M here: the module
> > +	  will be called ltc2983.
> > +
> >  config MAXIM_THERMOCOUPLE
> >  	tristate "Maxim thermocouple sensors"
> >  	depends on SPI
> > diff --git a/drivers/iio/temperature/Makefile
> > b/drivers/iio/temperature/Makefile
> > index baca4776ca0d..d6b850b0cf63 100644
> > --- a/drivers/iio/temperature/Makefile
> > +++ b/drivers/iio/temperature/Makefile
> > @@ -3,6 +3,7 @@
> >  # Makefile for industrial I/O temperature drivers
> >  #
> >  
> > +obj-$(CONFIG_LTC2983) += ltc2983.o
> >  obj-$(CONFIG_HID_SENSOR_TEMP) += hid-sensor-temperature.o
> >  obj-$(CONFIG_MAXIM_THERMOCOUPLE) += maxim_thermocouple.o
> >  obj-$(CONFIG_MAX31856) += max31856.o
> > diff --git a/drivers/iio/temperature/ltc2983.c
> > b/drivers/iio/temperature/ltc2983.c
> > new file mode 100644
> > index 000000000000..7c159da9f183
> > --- /dev/null
> > +++ b/drivers/iio/temperature/ltc2983.c
> > @@ -0,0 +1,1436 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Analog Devices LTC2983 Multi-Sensor Digital Temperature
> > Measurement System
> > + * driver
> > + *
> > + * Copyright 2019 Analog Devices Inc.
> > + */
> > +#include <linux/bitfield.h>
> > +#include <linux/completion.h>
> > +#include <linux/device.h>
> > +#include <linux/kernel.h>
> > +#include <linux/iio/iio.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/list.h>
> > +#include <linux/module.h>
> > +#include <linux/of_gpio.h>
> > +#include <linux/regmap.h>
> > +#include <linux/spi/spi.h>
> > +
> > +/* register map */
> > +#define LTC2983_STATUS_REG			0x0000
> > +#define LTC2983_TEMP_RES_START_REG		0x0010
> > +#define LTC2983_TEMP_RES_END_REG		0x005F
> > +#define LTC2983_GLOBAL_CONFIG_REG		0x00F0
> > +#define LTC2983_MULT_CHANNEL_START_REG		0x00F4
> > +#define LTC2983_MULT_CHANNEL_END_REG		0x00F7
> > +#define LTC2983_MUX_CONFIG_REG			0x00FF
> > +#define LTC2983_CHAN_ASSIGN_START_REG		0x0200
> > +#define LTC2983_CHAN_ASSIGN_END_REG		0x024F
> > +#define LTC2983_CUST_SENS_TBL_START_REG		0x0250
> > +#define LTC2983_CUST_SENS_TBL_END_REG		0x03CF
> > +
> > +#define LTC2983_DIFFERENTIAL_CHAN_MIN		2
> > +#define LTC2983_MAX_CHANNELS_NR			20
> > +#define LTC2983_MIN_CHANNELS_NR			1
> > +#define LTC2983_SLEEP				0x97
> > +#define LTC2983_CUSTOM_STEINHART_SIZE		24
> > +#define LTC2983_CUSTOM_SENSOR_ENTRY_SZ		6
> > +#define LTC2983_CUSTOM_STEINHART_ENTRY_SZ	4
> > +
> > +#define LTC2983_CHAN_START_ADDR(chan) \
> > +			(((chan - 1) * 4) +
> > LTC2983_CHAN_ASSIGN_START_REG)
> > +#define LTC2983_CHAN_RES_ADDR(chan) \
> > +			(((chan - 1) * 4) + LTC2983_TEMP_RES_START_REG)
> > +#define LTC2983_THERMOCOUPLE_DIFF_MASK		BIT(3)
> > +#define LTC2983_THERMISTOR_DIFF_MASK		BIT(2)
> > +#define LTC2983_DIODE_DIFF_MASK			BIT(2)
> > +#define LTC2983_RTD_4_WIRE_MASK			BIT(3)
> > +#define LTC2983_RTD_ROTATION_MASK		BIT(1)
> > +#define LTC2983_RTD_KELVIN_R_SENSE_MASK		GENMASK(3, 2)
> > +
> > +#define LTC2983_COMMON_HARD_FAULT_MASK	GENMASK(31, 30)
> > +#define LTC2983_COMMON_SOFT_FAULT_MASK	GENMASK(27, 25)
> > +
> > +#define	LTC2983_STATUS_START_MASK	BIT(7)
> > +#define	LTC2983_STATUS_START(x)		FIELD_PREP(LTC2983_
> > STATUS_START_MASK, x)
> > +
> > +#define	LTC2983_STATUS_CHAN_SEL_MASK	GENMASK(4, 0)
> > +#define	LTC2983_STATUS_CHAN_SEL(x) \
> > +				FIELD_PREP(LTC2983_STATUS_CHAN_SEL_MASK
> > , x)
> > +
> > +#define LTC2983_TEMP_UNITS_MASK		BIT(2)
> > +#define LTC2983_TEMP_UNITS(x)		FIELD_PREP(LTC2983_TEMP
> > _UNITS_MASK, x)
> > +
> > +#define LTC2983_NOTCH_FREQ_MASK		GENMASK(1, 0)
> > +#define LTC2983_NOTCH_FREQ(x)		FIELD_PREP(LTC2983_NOTC
> > H_FREQ_MASK, x)
> > +
> > +#define LTC2983_RES_VALID_MASK		BIT(24)
> > +#define LTC2983_DATA_MASK		GENMASK(23, 0)
> > +#define LTC2983_DATA_SIGN_BIT		23
> > +
> > +#define LTC2983_CHAN_TYPE_MASK		GENMASK(31, 27)
> > +#define LTC2983_CHAN_TYPE(x)		FIELD_PREP(LTC2983_CHAN
> > _TYPE_MASK, x)
> > +
> > +/* cold junction for thermocouples and rsense for rtd's and
> > thermistor's */
> > +#define LTC2983_CHAN_ASSIGN_MASK	GENMASK(26, 22)
> > +#define LTC2983_CHAN_ASSIGN(x)		FIELD_PREP(LTC2983_CHAN
> > _ASSIGN_MASK, x)
> > +
> > +#define LTC2983_CUSTOM_LEN_MASK		GENMASK(5, 0)
> > +#define LTC2983_CUSTOM_LEN(x)		FIELD_PREP(LTC2983_CUST
> > OM_LEN_MASK, x)
> > +
> > +#define LTC2983_CUSTOM_ADDR_MASK	GENMASK(11, 6)
> > +#define LTC2983_CUSTOM_ADDR(x)		FIELD_PREP(LTC2983_CUST
> > OM_ADDR_MASK, x)
> > +
> > +#define LTC2983_THERMOCOUPLE_CFG_MASK	GENMASK(21, 18)
> > +#define LTC2983_THERMOCOUPLE_CFG(x) \
> > +				FIELD_PREP(LTC2983_THERMOCOUPLE_CFG_MAS
> > K, x)
> > +#define LTC2983_THERMOCOUPLE_HARD_FAULT_MASK	GENMASK(31, 29)
> > +#define LTC2983_THERMOCOUPLE_SOFT_FAULT_MASK	GENMASK(28, 25)
> > +
> > +#define LTC2983_RTD_CFG_MASK		GENMASK(21, 18)
> > +#define LTC2983_RTD_CFG(x)		FIELD_PREP(LTC2983_RTD_CFG_MASK
> > , x)
> > +#define LTC2983_RTD_EXC_CURRENT_MASK	GENMASK(17, 14)
> > +#define LTC2983_RTD_EXC_CURRENT(x) \
> > +				FIELD_PREP(LTC2983_RTD_EXC_CURRENT_MASK
> > , x)
> > +#define LTC2983_RTD_CURVE_MASK		GENMASK(13, 12)
> > +#define LTC2983_RTD_CURVE(x)		FIELD_PREP(LTC2983_RTD_
> > CURVE_MASK, x)
> > +
> > +#define LTC2983_THERMISTOR_CFG_MASK	GENMASK(21, 19)
> > +#define LTC2983_THERMISTOR_CFG(x) \
> > +				FIELD_PREP(LTC2983_THERMISTOR_CFG_MASK,
> > x)
> > +#define LTC2983_THERMISTOR_EXC_CURRENT_MASK	GENMASK(18, 15)
> > +#define LTC2983_THERMISTOR_EXC_CURRENT(x) \
> > +			FIELD_PREP(LTC2983_THERMISTOR_EXC_CURRENT_MASK,
> > x)
> > +
> > +#define LTC2983_DIODE_CFG_MASK		GENMASK(26, 24)
> > +#define LTC2983_DIODE_CFG(x)		FIELD_PREP(LTC2983_DIOD
> > E_CFG_MASK, x)
> > +#define LTC2983_DIODE_EXC_CURRENT_MASK	GENMASK(23, 22)
> > +#define LTC2983_DIODE_EXC_CURRENT(x) \
> > +				FIELD_PREP(LTC2983_DIODE_EXC_CURRENT_MA
> > SK, x)
> > +#define LTC2983_DIODE_IDEAL_FACTOR_MASK	GENMASK(21, 0)
> > +#define LTC2983_DIODE_IDEAL_FACTOR(x) \
> > +				FIELD_PREP(LTC2983_DIODE_IDEAL_FACTOR_M
> > ASK, x)
> > +
> > +#define LTC2983_R_SENSE_VAL_MASK	GENMASK(26, 0)
> > +#define LTC2983_R_SENSE_VAL(x)		FIELD_PREP(LTC2983_R_SE
> > NSE_VAL_MASK, x)
> > +
> > +#define LTC2983_ADC_SINGLE_ENDED_MASK	BIT(26)
> > +#define LTC2983_ADC_SINGLE_ENDED(x) \
> > +				FIELD_PREP(LTC2983_ADC_SINGLE_ENDED_MAS
> > K, x)
> > +
> > +enum {
> > +	LTC2983_SENSOR_THERMOCOUPLE = 1,
> > +	LTC2983_SENSOR_THERMOCOUPLE_CUSTOM = 9,
> > +	LTC2983_SENSOR_RTD = 10,
> > +	LTC2983_SENSOR_RTD_CUSTOM = 18,
> > +	LTC2983_SENSOR_THERMISTOR = 19,
> > +	LTC2983_SENSOR_THERMISTOR_STEINHART = 26,
> > +	LTC2983_SENSOR_THERMISTOR_CUSTOM = 27,
> > +	LTC2983_SENSOR_DIODE = 28,
> > +	LTC2983_SENSOR_SENSE_RESISTOR = 29,
> > +	LTC2983_SENSOR_DIRECT_ADC = 30,
> > +};
> > +
> > +#define to_thermocouple(_sensor) \
> > +		container_of(_sensor, struct ltc2983_thermocouple,
> > sensor)
> > +
> > +#define to_rtd(_sensor) \
> > +		container_of(_sensor, struct ltc2983_rtd, sensor)
> > +
> > +#define to_thermistor(_sensor) \
> > +		container_of(_sensor, struct ltc2983_thermistor,
> > sensor)
> > +
> > +#define to_diode(_sensor) \
> > +		container_of(_sensor, struct ltc2983_diode, sensor)
> > +
> > +#define to_rsense(_sensor) \
> > +		container_of(_sensor, struct ltc2983_rsense, sensor)
> > +
> > +#define to_adc(_sensor) \
> > +		container_of(_sensor, struct ltc2983_adc, sensor)
> > +
> > +struct ltc2983_data {
> > +	struct regmap *regmap;
> > +	struct spi_device *spi;
> > +	struct mutex lock;
> > +	struct completion completion;
> > +	struct iio_chan_spec *iio_chan;
> > +	struct ltc2983_sensor **sensors;
> > +	u32 mux_delay_config;
> > +	u32 filter_notch_freq;
> > +	u16 custom_table_size;
> > +	u8 num_channels;
> > +	u8 iio_channels;
> > +	bool temp_farenheit;
> > +	bool sleep;
> > +};
> > +
> > +struct ltc2983_sensor {
> > +	int (*fault_handler)(const struct ltc2983_data *st, const u32
> > result);
> > +	int (*assign_chan)(struct ltc2983_data *st,
> > +			   const struct ltc2983_sensor *sensor);
> > +	/* specifies the sensor channel */
> > +	u32 chan;
> > +	/* sensor type */
> > +	u32 type;
> > +};
> > +
> > +struct ltc2983_custom_sensor {
> > +	/* raw table sensor data */
> > +	u8 *table;
> > +	size_t size;
> > +	/* address offset */
> > +	s8 offset;
> > +	bool is_steinhart;
> > +};
> > +
> > +struct ltc2983_thermocouple {
> > +	struct ltc2983_sensor sensor;
> > +	struct ltc2983_custom_sensor *custom;
> > +	u32 sensor_config;
> > +	u32 cold_junction_chan;
> > +};
> > +
> > +struct ltc2983_rtd {
> > +	struct ltc2983_sensor sensor;
> > +	struct ltc2983_custom_sensor *custom;
> > +	u32 sensor_config;
> > +	u32 r_sense_chan;
> > +	u32 excitation_current;
> > +	u32 rtd_curve;
> > +};
> > +
> > +struct ltc2983_thermistor {
> > +	struct ltc2983_sensor sensor;
> > +	struct ltc2983_custom_sensor *custom;
> > +	u32 sensor_config;
> > +	u32 r_sense_chan;
> > +	u32 excitation_current;
> > +};
> > +
> > +struct ltc2983_diode {
> > +	struct ltc2983_sensor sensor;
> > +	u32 sensor_config;
> > +	u32 excitation_current;
> > +	u32 ideal_factor_value;
> > +};
> > +
> > +struct ltc2983_rsense {
> > +	struct ltc2983_sensor sensor;
> > +	u32 r_sense_val;
> > +};
> > +
> > +struct ltc2983_adc {
> > +	struct ltc2983_sensor sensor;
> > +	bool single_ended;
> > +};
> > +
> > +/*
> > + * Convert to Q format numbers. These number's are integers where
> > + * the number of integer and fractional bits are specified. The
> > resolution
> > + * is given by 1/@resolution and tell us the number of fractional
> > bits. For
> > + * instance a resolution of 2^-10 means we have 10 fractional
> > bits.
> > + */
> > +static u32 __convert_to_raw(const u64 val, const u32 resolution)
> > +{
> > +	u64 __res = val * resolution;
> > +
> > +	/* all values are multiplied by 1000000 to remove the fraction
> > */
> > +	do_div(__res, 1000000);
> > +
> > +	return __res;
> > +}
> > +
> > +static u32 __convert_to_raw_sign(const u64 val, const u32
> > resolution)
> > +{
> > +	s64 __res = -(s32)val;
> > +
> > +	__res = __convert_to_raw(__res, resolution);
> > +
> > +	return (u32)-__res;
> > +}
> > +
> > +static int __ltc2983_fault_handler(const struct ltc2983_data *st,
> > +				   const u32 result, const u32
> > hard_mask,
> > +				   const u32 soft_mask)
> > +{
> > +	const struct device *dev = &st->spi->dev;
> > +
> > +	if (result & hard_mask) {
> > +		dev_err(dev, "Invalid conversion: Sensor HARD
> > fault\n");
> > +		return -EIO;
> > +	} else if (result & soft_mask) {
> > +		/* just print a warning */
> > +		dev_warn(dev, "Suspicious conversion: Sensor SOFT
> > fault\n");
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int __ltc2983_chan_assign_common(const struct ltc2983_data
> > *st,
> > +					const struct ltc2983_sensor
> > *sensor,
> > +					u32 chan_val)
> > +{
> > +	u32 reg = LTC2983_CHAN_START_ADDR(sensor->chan);
> > +	__be32 __chan_val;
> > +
> > +	chan_val |= LTC2983_CHAN_TYPE(sensor->type);
> > +	dev_dbg(&st->spi->dev, "Assign reg:0x%04X, val:0x%08X\n", reg,
> > +								chan_va
> > l);
> > +	__chan_val = cpu_to_be32(chan_val);
> > +	return regmap_bulk_write(st->regmap, reg, &__chan_val,
> > +				 sizeof(__chan_val));
> > +}
> > +
> > +static int __ltc2983_chan_custom_sensor_assign(struct ltc2983_data
> > *st,
> > +					  struct ltc2983_custom_sensor
> > *custom,
> > +					  u32 *chan_val)
> > +{
> > +	u32 reg;
> > +	u8 mult = custom->is_steinhart ?
> > LTC2983_CUSTOM_STEINHART_ENTRY_SZ :
> > +		LTC2983_CUSTOM_SENSOR_ENTRY_SZ;
> > +	const struct device *dev = &st->spi->dev;
> > +	/*
> > +	 * custom->size holds the raw size of the table. However, when
> > +	 * configuring the sensor channel, we must write the number of
> > +	 * entries of the table minus 1. For steinhart sensors 0 is
> > written
> > +	 * since the size is constant!
> > +	 */
> > +	const u8 len = custom->is_steinhart ? 0 :
> > +		(custom->size / LTC2983_CUSTOM_SENSOR_ENTRY_SZ) - 1;
> > +	/*
> > +	 * Check if the offset was assigned already. It should be for
> > steinhart
> > +	 * sensors. When coming from sleep, it should be assigned for
> > all.
> > +	 */
> > +	if (custom->offset < 0) {
> > +		/*
> > +		 * This needs to be done again here because, from the
> > moment
> > +		 * when this test was done (successfully) for this
> > custom
> > +		 * sensor, a steinhart sensor might have been added
> > changing
> > +		 * custom_table_size...
> > +		 */
> > +		if (st->custom_table_size + custom->size >
> > +		    (LTC2983_CUST_SENS_TBL_END_REG -
> > +		     LTC2983_CUST_SENS_TBL_START_REG) + 1) {
> > +			dev_err(dev,
> > +				"Not space left(%d) for new custom
> > sensor(%zu)",
> > +							st-
> > >custom_table_size,
> > +							custom->size);
> > +			return -EINVAL;
> > +		}
> > +
> > +		custom->offset = st->custom_table_size /
> > +					LTC2983_CUSTOM_SENSOR_ENTRY_SZ;
> > +		st->custom_table_size += custom->size;
> > +	}
> > +
> > +	reg = (custom->offset * mult) +
> > LTC2983_CUST_SENS_TBL_START_REG;
> > +
> > +	*chan_val |= LTC2983_CUSTOM_LEN(len);
> > +	*chan_val |= LTC2983_CUSTOM_ADDR(custom->offset);
> > +	dev_dbg(dev, "Assign custom sensor, reg:0x%04X, off:%d,
> > sz:%zu",
> > +							reg, custom-
> > >offset,
> > +							custom->size);
> > +	/* write custom sensor table */
> > +	return regmap_bulk_write(st->regmap, reg, custom->table,
> > custom->size);
> > +}
> > +
> > +static struct ltc2983_custom_sensor *__ltc2983_custom_sensor_new(
> > +						struct ltc2983_data
> > *st,
> > +						const struct
> > device_node *np,
> > +						const bool
> > is_steinhart,
> > +						const u32 resolution,
> > +						const bool has_signed)
> > +{
> > +	struct ltc2983_custom_sensor *new_custom;
> > +	u8 index, n_entries, tbl = 0;
> > +	struct device *dev = &st->spi->dev;
> > +	/*
> > +	 * For custom steinhart, the full u32 is taken. For all the
> > others
> > +	 * the MSB is discarded.
> > +	 */
> > +	const u8 n_size = (is_steinhart == true) ? 4 : 3;
> > +
> > +	n_entries = of_property_count_elems_of_size(np, "adi,custom-
> > sensor",
> > +						sizeof(u64));
> > +	/* n_entries must be an even number */
> > +	if (!n_entries || (n_entries % 2) != 0) {
> > +		dev_err(dev, "Number of entries either 0 or not
> > even\n");
> > +		return ERR_PTR(-EINVAL);
> > +	}
> > +
> > +	new_custom = devm_kzalloc(dev, sizeof(*new_custom),
> > GFP_KERNEL);
> > +	if (!new_custom)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	new_custom->size = n_entries * n_size;
> > +	/* check Steinhart size */
> > +	if (is_steinhart && new_custom->size !=
> > LTC2983_CUSTOM_STEINHART_SIZE) {
> > +		dev_err(dev, "Steinhart sensors size(%zu) must be 24",
> > +							new_custom-
> > >size);
> > +		return ERR_PTR(-EINVAL);
> > +	}
> > +	/* Check space on the table. */
> > +	if (st->custom_table_size + new_custom->size >
> > +	    (LTC2983_CUST_SENS_TBL_END_REG -
> > +	     LTC2983_CUST_SENS_TBL_START_REG) + 1) {
> > +		dev_err(dev, "No space left(%d) for new custom
> > sensor(%zu)",
> > +				st->custom_table_size, new_custom-
> > >size);
> > +		return ERR_PTR(-EINVAL);
> > +	}
> > +
> > +	/* allocate the table */
> > +	new_custom->table = devm_kzalloc(dev, new_custom->size,
> > GFP_KERNEL);
> > +	if (!new_custom->table)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	for (index = 0; index < n_entries; index++) {
> > +		u64 temp = 0, j;
> > +
> > +		of_property_read_u64_index(np, "adi,custom-sensor",
> > index,
> > +					   &temp);
> > +		/*
> > +		 * Steinhart sensors are configured with raw values in
> > the
> > +		 * devicetree. For the other sensors we must convert
> > the
> > +		 * value to raw. The odd index's correspond to
> > temperarures
> > +		 * and always have 1/1024 of resolution. Temperatures
> > also
> > +		 * come in kelvin, so signed values is not possible
> > +		 */
> > +		if (!is_steinhart) {
> > +			if ((index % 2) != 0)
> > +				temp = __convert_to_raw(temp, 1024);
> > +			else if (has_signed && (s64)temp < 0)
> > +				temp = __convert_to_raw_sign(temp,
> > resolution);
> > +			else
> > +				temp = __convert_to_raw(temp,
> > resolution);
> > +		}
> > +
> > +		for (j = 0; j < n_size; j++)
> > +			new_custom->table[tbl++] =
> > +				temp >> (8 * (n_size - j - 1));
> > +	}
> > +
> > +	new_custom->is_steinhart = is_steinhart;
> > +	/*
> > +	 * This is done to first add all the steinhart sensors to the
> > table,
> > +	 * in order to maximize the table usage. If we mix adding
> > steinhart
> > +	 * with the other sensors, we might have to do some roundup to
> > make
> > +	 * sure that sensor_addr - 0x250(start address) is a multiple
> > of 4
> > +	 * (for steinhart), and a multiple of 6 for all the other
> > sensors.
> > +	 * Since we have const 24 bytes for steinhart sensors and 24 is
> > +	 * also a multiple of 6, we guarantee that the first non-
> > steinhart
> > +	 * sensor will sit in a correct address without the need of
> > filling
> > +	 * addresses.
> > +	 */
> > +	if (is_steinhart) {
> > +		new_custom->offset = st->custom_table_size /
> > +					LTC2983_CUSTOM_STEINHART_ENTRY_
> > SZ;
> > +		st->custom_table_size += new_custom->size;
> > +	} else {
> > +		/* mark as unset. This is checked later on the assign
> > phase */
> > +		new_custom->offset = -1;
> > +	}
> > +
> > +	return new_custom;
> > +}
> > +
> > +static int ltc2983_thermocouple_fault_handler(const struct
> > ltc2983_data *st,
> > +					      const u32 result)
> > +{
> > +	return __ltc2983_fault_handler(st, result,
> > +				       LTC2983_THERMOCOUPLE_HARD_FAULT_
> > MASK,
> > +				       LTC2983_THERMOCOUPLE_SOFT_FAULT_
> > MASK);
> > +}
> > +
> > +static int ltc2983_common_fault_handler(const struct ltc2983_data
> > *st,
> > +					const u32 result)
> > +{
> > +	return __ltc2983_fault_handler(st, result,
> > +				       LTC2983_COMMON_HARD_FAULT_MASK,
> > +				       LTC2983_COMMON_SOFT_FAULT_MASK);
> > +}
> > +
> > +static int ltc2983_thermocouple_assign_chan(struct ltc2983_data
> > *st,
> > +				const struct ltc2983_sensor *sensor)
> > +{
> > +	struct ltc2983_thermocouple *thermo = to_thermocouple(sensor);
> > +	u32 chan_val;
> > +
> > +	chan_val = LTC2983_CHAN_ASSIGN(thermo->cold_junction_chan);
> > +	chan_val |= LTC2983_THERMOCOUPLE_CFG(thermo->sensor_config);
> > +
> > +	if (thermo->custom) {
> > +		int ret;
> > +
> > +		ret = __ltc2983_chan_custom_sensor_assign(st, thermo-
> > >custom,
> > +							  &chan_val);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +	return __ltc2983_chan_assign_common(st, sensor, chan_val);
> > +}
> > +
> > +static int ltc2983_rtd_assign_chan(struct ltc2983_data *st,
> > +				   const struct ltc2983_sensor *sensor)
> > +{
> > +	struct ltc2983_rtd *rtd = to_rtd(sensor);
> > +	u32 chan_val;
> > +
> > +	chan_val = LTC2983_CHAN_ASSIGN(rtd->r_sense_chan);
> > +	chan_val |= LTC2983_RTD_CFG(rtd->sensor_config);
> > +	chan_val |= LTC2983_RTD_EXC_CURRENT(rtd->excitation_current);
> > +	chan_val |= LTC2983_RTD_CURVE(rtd->rtd_curve);
> > +
> > +	if (rtd->custom) {
> > +		int ret;
> > +
> > +		ret = __ltc2983_chan_custom_sensor_assign(st, rtd-
> > >custom,
> > +							  &chan_val);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +	return __ltc2983_chan_assign_common(st, sensor, chan_val);
> > +}
> > +
> > +static int ltc2983_thermistor_assign_chan(struct ltc2983_data *st,
> > +					  const struct ltc2983_sensor
> > *sensor)
> > +{
> > +	struct ltc2983_thermistor *thermistor = to_thermistor(sensor);
> > +	u32 chan_val;
> > +
> > +	chan_val = LTC2983_CHAN_ASSIGN(thermistor->r_sense_chan);
> > +	chan_val |= LTC2983_THERMISTOR_CFG(thermistor->sensor_config);
> > +	chan_val |=
> > +		LTC2983_THERMISTOR_EXC_CURRENT(thermistor-
> > >excitation_current);
> > +
> > +	if (thermistor->custom) {
> > +		int ret;
> > +
> > +		ret = __ltc2983_chan_custom_sensor_assign(st,
> > +							  thermistor-
> > >custom,
> > +							  &chan_val);
> > +		if (ret)
> > +			return ret;
> > +	}
> > +	return __ltc2983_chan_assign_common(st, sensor, chan_val);
> > +}
> > +
> > +static int ltc2983_diode_assign_chan(struct ltc2983_data *st,
> > +				     const struct ltc2983_sensor
> > *sensor)
> > +{
> > +	struct ltc2983_diode *diode = to_diode(sensor);
> > +	u32 chan_val;
> > +
> > +	chan_val = LTC2983_DIODE_CFG(diode->sensor_config);
> > +	chan_val |= LTC2983_DIODE_EXC_CURRENT(diode-
> > >excitation_current);
> > +	chan_val |= LTC2983_DIODE_IDEAL_FACTOR(diode-
> > >ideal_factor_value);
> > +
> > +	return __ltc2983_chan_assign_common(st, sensor, chan_val);
> > +}
> > +
> > +static int ltc2983_r_sense_assign_chan(struct ltc2983_data *st,
> > +				       const struct ltc2983_sensor
> > *sensor)
> > +{
> > +	struct ltc2983_rsense *rsense = to_rsense(sensor);
> > +	u32 chan_val;
> > +
> > +	chan_val = LTC2983_R_SENSE_VAL(rsense->r_sense_val);
> > +
> > +	return __ltc2983_chan_assign_common(st, sensor, chan_val);
> > +}
> > +
> > +static int ltc2983_adc_assign_chan(struct ltc2983_data *st,
> > +				   const struct ltc2983_sensor *sensor)
> > +{
> > +	struct ltc2983_adc *adc = to_adc(sensor);
> > +	u32 chan_val;
> > +
> > +	chan_val = LTC2983_ADC_SINGLE_ENDED(adc->single_ended);
> > +
> > +	return __ltc2983_chan_assign_common(st, sensor, chan_val);
> > +}
> > +
> > +static struct ltc2983_sensor *ltc2983_thermocouple_new(
> > +					const struct device_node
> > *child,
> > +					struct ltc2983_data *st,
> > +					const struct ltc2983_sensor
> > *sensor)
> > +{
> > +	struct ltc2983_thermocouple *thermo;
> > +	struct device_node *phandle;
> > +
> > +	thermo = devm_kzalloc(&st->spi->dev, sizeof(*thermo),
> > GFP_KERNEL);
> > +	if (!thermo)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	of_property_read_u32(child, "adi,sensor-config",
> > +				 &thermo->sensor_config);
> > +	/* validate channel index */
> > +	if (!(thermo->sensor_config & LTC2983_THERMOCOUPLE_DIFF_MASK)
> > &&
> > +	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
> > +		dev_err(&st->spi->dev,
> > +			"Invalid chann:%d for differential
> > thermocouple",
> > +								sensor-
> > >chan);
> > +		return ERR_PTR(-EINVAL);
> > +	}
> > +
> > +	phandle = of_parse_phandle(child, "adi,cold-junction-handle",
> > 0);
> > +	if (phandle) {
> > +		int ret;
> > +
> > +		ret = of_property_read_u32(phandle, "reg",
> > +					   &thermo-
> > >cold_junction_chan);
> > +		if (ret) {
> > +			/*
> > +			 * This would be catched later but we can just
> > return
> > +			 * the error right away.
> > +			 */
> > +			dev_err(&st->spi->dev, "Property reg must be
> > given\n");
> > +			of_node_put(phandle);
> > +			return ERR_PTR(-EINVAL);
> > +		}
> > +	}
> > +
> > +	/* check custom sensor */
> > +	if (sensor->type == LTC2983_SENSOR_THERMOCOUPLE_CUSTOM) {
> > +		thermo->custom = __ltc2983_custom_sensor_new(st, child,
> > false,
> > +							     16384,
> > true);
> > +		if (IS_ERR(thermo->custom)) {
> > +			of_node_put(phandle);
> > +			return ERR_CAST(thermo->custom);
> > +		}
> > +	}
> > +
> > +	/* set common parameters */
> > +	thermo->sensor.fault_handler =
> > ltc2983_thermocouple_fault_handler;
> > +	thermo->sensor.assign_chan = ltc2983_thermocouple_assign_chan;
> > +
> > +	of_node_put(phandle);
> > +	return &thermo->sensor;
> > +}
> > +
> > +static struct ltc2983_sensor *ltc2983_rtd_new(const struct
> > device_node *child,
> > +					  struct ltc2983_data *st,
> > +					  const struct ltc2983_sensor
> > *sensor)
> > +{
> > +	struct ltc2983_rtd *rtd;
> > +	int ret = 0;
> > +	struct device *dev = &st->spi->dev;
> > +	struct device_node *phandle;
> > +	u32 excitation_current = 0;
> > +
> > +	rtd = devm_kzalloc(dev, sizeof(*rtd), GFP_KERNEL);
> > +	if (!rtd)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	phandle = of_parse_phandle(child, "adi,rsense-handle", 0);
> > +	if (!phandle) {
> > +		dev_err(dev, "Property adi,rsense-handle missing or
> > invalid");
> > +		return ERR_PTR(-EINVAL);
> > +	}
> > +
> > +	ret = of_property_read_u32(phandle, "reg", &rtd->r_sense_chan);
> > +	if (ret) {
> > +		dev_err(dev, "Property reg must be given\n");
> > +		goto fail;
> > +	}
> > +
> > +	of_property_read_u32(child, "adi,sensor-config", &rtd-
> > >sensor_config);
> > +	/*
> > +	 * rtd channel indexes are a bit more complicated to validate.
> > +	 * For 4wire RTD with rotation, the channel selection cannot be
> > +	 * >=19 since the chann + 1 is used in this configuration.
> > +	 * For 4wire RTDs with kelvin rsense, the rsense channel cannot
> > be
> > +	 * <=1 since chanel - 1 and channel - 2 are used.
> > +	 */
> > +	if (rtd->sensor_config & LTC2983_RTD_4_WIRE_MASK) {
> > +		/* 4-wire */
> > +		u8 min = LTC2983_DIFFERENTIAL_CHAN_MIN,
> > +			max = LTC2983_MAX_CHANNELS_NR;
> > +
> > +		if (rtd->sensor_config & LTC2983_RTD_ROTATION_MASK)
> > +			max = LTC2983_MAX_CHANNELS_NR - 1;
> > +
> > +		if (((rtd->sensor_config &
> > LTC2983_RTD_KELVIN_R_SENSE_MASK)
> > +		     == LTC2983_RTD_KELVIN_R_SENSE_MASK) &&
> > +		    (rtd->r_sense_chan <=  min)) {
> > +			/* kelvin rsense*/
> > +			dev_err(dev,
> > +				"Invalid rsense chann:%d to use in
> > kelvin rsense",
> > +							rtd-
> > >r_sense_chan);
> > +
> > +			ret = -EINVAL;
> > +			goto fail;
> > +		}
> > +
> > +		if (sensor->chan < min || sensor->chan > max) {
> > +			dev_err(dev, "Invalid chann:%d for the rtd
> > config",
> > +								sensor-
> > >chan);
> > +
> > +			ret = -EINVAL;
> > +			goto fail;
> > +		}
> > +	} else {
> > +		/* same as differential case */
> > +		if (sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
> > +			dev_err(&st->spi->dev,
> > +				"Invalid chann:%d for RTD", sensor-
> > >chan);
> > +
> > +			ret = -EINVAL;
> > +			goto fail;
> > +		}
> > +	}
> > +
> > +	/* check custom sensor */
> > +	if (sensor->type == LTC2983_SENSOR_RTD_CUSTOM) {
> > +		rtd->custom = __ltc2983_custom_sensor_new(st, child,
> > false,
> > +							  2048, false);
> > +		if (IS_ERR(rtd->custom)) {
> > +			of_node_put(phandle);
> > +			return ERR_CAST(rtd->custom);
> > +		}
> > +	}
> > +
> > +	/* set common parameters */
> > +	rtd->sensor.fault_handler = ltc2983_common_fault_handler;
> > +	rtd->sensor.assign_chan = ltc2983_rtd_assign_chan;
> > +
> > +	ret = of_property_read_u32(child, "adi,excitation-current-
> > microamp",
> > +				   &excitation_current);
> > +	if (ret) {
> > +		/* default to 5uA */
> > +		rtd->excitation_current = 1;
> > +	} else {
> > +		switch (excitation_current) {
> > +		case 5:
> > +			rtd->excitation_current = 0x01;
> > +			break;
> > +		case 10:
> > +			rtd->excitation_current = 0x02;
> > +			break;
> > +		case 25:
> > +			rtd->excitation_current = 0x03;
> > +			break;
> > +		case 50:
> > +			rtd->excitation_current = 0x04;
> > +			break;
> > +		case 100:
> > +			rtd->excitation_current = 0x05;
> > +			break;
> > +		case 250:
> > +			rtd->excitation_current = 0x06;
> > +			break;
> > +		case 500:
> > +			rtd->excitation_current = 0x07;
> > +			break;
> > +		case 1000:
> > +			rtd->excitation_current = 0x08;
> > +			break;
> > +		default:
> > +			dev_err(&st->spi->dev,
> > +				"Invalid value for excitation
> > current(%u)",
> > +							excitation_curr
> > ent);
> > +			ret = -EINVAL;
> > +			goto fail;
> > +		}
> > +	}
> > +
> > +	of_property_read_u32(child, "adi,rtd-curve", &rtd->rtd_curve);
> > +
> > +	of_node_put(phandle);
> > +	return &rtd->sensor;
> > +fail:
> > +	of_node_put(phandle);
> > +	return ERR_PTR(ret);
> > +}
> > +
> > +static struct ltc2983_sensor *ltc2983_thermistor_new(
> > +					const struct device_node
> > *child,
> > +					struct ltc2983_data *st,
> > +					const struct ltc2983_sensor
> > *sensor)
> > +{
> > +	struct ltc2983_thermistor *thermistor;
> > +	struct device *dev = &st->spi->dev;
> > +	struct device_node *phandle;
> > +	u32 excitation_current = 0;
> > +	int ret = 0;
> > +
> > +	thermistor = devm_kzalloc(dev, sizeof(*thermistor),
> > GFP_KERNEL);
> > +	if (!thermistor)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	phandle = of_parse_phandle(child, "adi,rsense-handle", 0);
> > +	if (!phandle) {
> > +		dev_err(dev, "Property adi,rsense-handle missing or
> > invalid");
> > +		return ERR_PTR(-EINVAL);
> > +	}
> > +
> > +	ret = of_property_read_u32(phandle, "reg", &thermistor-
> > >r_sense_chan);
> > +	if (ret) {
> > +		dev_err(dev, "rsense channel must be configured...\n");
> > +		goto fail;
> > +	}
> > +
> > +	of_property_read_u32(child, "adi,sensor-config",
> > +			     &thermistor->sensor_config);
> > +	/* validate channel index */
> > +	if (!(thermistor->sensor_config & LTC2983_THERMISTOR_DIFF_MASK)
> > &&
> > +	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
> > +		dev_err(&st->spi->dev,
> > +			"Invalid chann:%d for differential thermistor",
> > +								sensor-
> > >chan);
> > +		ret = -EINVAL;
> > +		goto fail;
> > +	}
> > +
> > +	/* check custom sensor */
> > +	if (sensor->type >= LTC2983_SENSOR_THERMISTOR_STEINHART) {
> > +		thermistor->custom = __ltc2983_custom_sensor_new(st,
> > child,
> > +			sensor->type ==
> > LTC2983_SENSOR_THERMISTOR_STEINHART ?
> > +							  true : false,
> > 64,
> > +							  false);
> > +		if (IS_ERR(thermistor->custom)) {
> > +			of_node_put(phandle);
> > +			return ERR_CAST(thermistor->custom);
> > +		}
> > +	}
> > +	/* set common parameters */
> > +	thermistor->sensor.fault_handler =
> > ltc2983_common_fault_handler;
> > +	thermistor->sensor.assign_chan =
> > ltc2983_thermistor_assign_chan;
> > +
> > +	ret = of_property_read_u32(child, "adi,excitation-current-
> > nanoamp",
> > +				   &excitation_current);
> > +	if (ret) {
> > +		/* Auto range is not allowed for custom sensors */
> > +		if (sensor->type >=
> > LTC2983_SENSOR_THERMISTOR_STEINHART)
> > +			/* default to 1uA */
> > +			thermistor->excitation_current = 0x03;
> > +		else
> > +			/* default to auto-range */
> > +			thermistor->excitation_current = 0x0c;
> > +	} else {
> > +		switch (excitation_current) {
> > +		case 0:
> > +			/* auto range */
> > +			if (sensor->type >=
> > +			    LTC2983_SENSOR_THERMISTOR_STEINHART) {
> > +				dev_err(&st->spi->dev,
> > +					"Auto Range not allowed for
> > custom sensors\n");
> > +				ret = -EINVAL;
> > +				goto fail;
> > +			}
> > +			thermistor->excitation_current = 0x0c;
> > +			break;
> > +		case 250:
> > +			thermistor->excitation_current = 0x01;
> > +			break;
> > +		case 500:
> > +			thermistor->excitation_current = 0x02;
> > +			break;
> > +		case 1000:
> > +			thermistor->excitation_current = 0x03;
> > +			break;
> > +		case 5000:
> > +			thermistor->excitation_current = 0x04;
> > +			break;
> > +		case 10000:
> > +			thermistor->excitation_current = 0x05;
> > +			break;
> > +		case 25000:
> > +			thermistor->excitation_current = 0x06;
> > +			break;
> > +		case 50000:
> > +			thermistor->excitation_current = 0x07;
> > +			break;
> > +		case 100000:
> > +			thermistor->excitation_current = 0x08;
> > +			break;
> > +		case 250000:
> > +			thermistor->excitation_current = 0x09;
> > +			break;
> > +		case 500000:
> > +			thermistor->excitation_current = 0x0a;
> > +			break;
> > +		case 1000000:
> > +			thermistor->excitation_current = 0x0b;
> > +			break;
> > +		default:
> > +			dev_err(&st->spi->dev,
> > +				"Invalid value for excitation
> > current(%u)",
> > +							excitation_curr
> > ent);
> > +			ret = -EINVAL;
> > +			goto fail;
> > +		}
> > +	}
> > +
> > +	of_node_put(phandle);
> > +	return &thermistor->sensor;
> > +fail:
> > +	of_node_put(phandle);
> > +	return ERR_PTR(ret);
> > +}
> > +
> > +static struct ltc2983_sensor *ltc2983_diode_new(
> > +					const struct device_node
> > *child,
> > +					const struct ltc2983_data *st,
> > +					const struct ltc2983_sensor
> > *sensor)
> > +{
> > +	struct ltc2983_diode *diode;
> > +	u32 temp = 0, excitation_current = 0;
> > +	int ret;
> > +
> > +	diode = devm_kzalloc(&st->spi->dev, sizeof(*diode),
> > GFP_KERNEL);
> > +	if (!diode)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	of_property_read_u32(child, "adi,sensor-config", &diode-
> > >sensor_config);
> > +	/* validate channel index */
> > +	if (!(diode->sensor_config & LTC2983_DIODE_DIFF_MASK) &&
> > +	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
> > +		dev_err(&st->spi->dev,
> > +			"Invalid chann:%d for differential thermistor",
> > +								sensor-
> > >chan);
> > +		return ERR_PTR(-EINVAL);
> > +	}
> > +	/* set common parameters */
> > +	diode->sensor.fault_handler = ltc2983_common_fault_handler;
> > +	diode->sensor.assign_chan = ltc2983_diode_assign_chan;
> > +
> > +	ret = of_property_read_u32(child, "adi,excitation-current-
> > microamp",
> > +				   &excitation_current);
> > +	if (!ret) {
> > +		switch (excitation_current) {
> > +		case 10:
> > +			diode->excitation_current = 0x00;
> > +			break;
> > +		case 20:
> > +			diode->excitation_current = 0x01;
> > +			break;
> > +		case 40:
> > +			diode->excitation_current = 0x02;
> > +			break;
> > +		case 80:
> > +			diode->excitation_current = 0x03;
> > +			break;
> > +		default:
> > +			dev_err(&st->spi->dev,
> > +				"Invalid value for excitation
> > current(%u)",
> > +							excitation_curr
> > ent);
> > +			return ERR_PTR(-EINVAL);
> > +		}
> > +	}
> > +
> > +	of_property_read_u32(child, "adi,ideal-factor-value", &temp);
> > +
> > +	/* 2^20 resolution */
> > +	diode->ideal_factor_value = __convert_to_raw(temp, 1048576);
> > +
> > +	return &diode->sensor;
> > +}
> > +
> > +static struct ltc2983_sensor *ltc2983_r_sense_new(struct
> > device_node *child,
> > +					struct ltc2983_data *st,
> > +					const struct ltc2983_sensor
> > *sensor)
> > +{
> > +	struct ltc2983_rsense *rsense;
> > +	int ret;
> > +	u64 temp;
> > +
> > +	rsense = devm_kzalloc(&st->spi->dev, sizeof(*rsense),
> > GFP_KERNEL);
> > +	if (!rsense)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	/* validate channel index */
> > +	if (sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
> > +		dev_err(&st->spi->dev, "Invalid chann:%d for r_sense",
> > +							sensor->chan);
> > +		return ERR_PTR(-EINVAL);
> > +	}
> > +	/* get raw value */
> > +	ret = of_property_read_u64(child, "adi,rsense-val-micro-ohms",
> > &temp);
> > +	if (ret) {
> > +		dev_err(&st->spi->dev, "Property adi,rsense-val-micro-
> > ohms missing\n");
> > +		return ERR_PTR(-EINVAL);
> > +	}
> > +
> > +	/* 2^10 resolution */
> > +	rsense->r_sense_val = __convert_to_raw(temp, 1024);
> > +
> > +	/* set common parameters */
> > +	rsense->sensor.assign_chan = ltc2983_r_sense_assign_chan;
> > +
> > +	return &rsense->sensor;
> > +}
> > +
> > +static struct ltc2983_sensor *ltc2983_adc_new(struct device_node
> > *child,
> > +					 struct ltc2983_data *st,
> > +					 const struct ltc2983_sensor
> > *sensor)
> > +{
> > +	struct ltc2983_adc *adc;
> > +
> > +	adc = devm_kzalloc(&st->spi->dev, sizeof(*adc), GFP_KERNEL);
> > +	if (!adc)
> > +		return ERR_PTR(-ENOMEM);
> > +
> > +	if (of_property_read_bool(child, "adi,single-ended"))
> > +		adc->single_ended = true;
> > +
> > +	if (!adc->single_ended &&
> > +	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
> > +		dev_err(&st->spi->dev, "Invalid chan:%d for
> > differential adc\n",
> > +								sensor-
> > >chan);
> > +		return ERR_PTR(-EINVAL);
> > +	}
> > +	/* set common parameters */
> > +	adc->sensor.assign_chan = ltc2983_adc_assign_chan;
> > +	adc->sensor.fault_handler = ltc2983_common_fault_handler;
> > +
> > +	return &adc->sensor;
> > +}
> > +
> > +static int ltc2983_chan_read(struct ltc2983_data *st,
> > +			const struct ltc2983_sensor *sensor, int *val)
> > +{
> > +	u32 start_conversion = 0;
> > +	int ret;
> > +	unsigned long time;
> > +	__be32 temp;
> > +
> > +	/*
> > +	 * Do not allow channel readings if device is in sleep state.
> > +	 * A read/write on the spi bus would bring the device
> > prematurely
> > +	 * out of sleep.
> > +	 */
> > +	if (st->sleep)
> > +		return -EPERM;
> > +
> > +	start_conversion = LTC2983_STATUS_START(true);
> > +	start_conversion |= LTC2983_STATUS_CHAN_SEL(sensor->chan);
> > +	dev_dbg(&st->spi->dev, "Start conversion on chan:%d,
> > status:%02X\n",
> > +		sensor->chan, start_conversion);
> > +	/* start conversion */
> > +	ret = regmap_write(st->regmap, LTC2983_STATUS_REG,
> > start_conversion);
> > +	if (ret)
> > +		return ret;
> > +
> > +	reinit_completion(&st->completion);
> > +	/*
> > +	 * wait for conversion to complete.
> > +	 * 300 ms should be more than enough to complete the
> > conversion.
> > +	 * Depending on the sensor configuration, there are 2/3
> > conversions
> > +	 * cycles of 82ms.
> > +	 */
> > +	time = wait_for_completion_timeout(&st->completion,
> > +					   msecs_to_jiffies(300));
> > +	if (!time) {
> > +		dev_warn(&st->spi->dev, "Conversion timed out\n");
> > +		return -ETIMEDOUT;
> > +	}
> > +
> > +	/* read the converted data */
> > +	ret = regmap_bulk_read(st->regmap,
> > LTC2983_CHAN_RES_ADDR(sensor->chan),
> > +			       &temp, sizeof(temp));
> > +	if (ret)
> > +		return ret;
> > +
> > +	*val = __be32_to_cpu(temp);
> > +
> > +	if (!(LTC2983_RES_VALID_MASK & *val)) {
> > +		dev_err(&st->spi->dev, "Invalid conversion
> > detected\n");
> > +		return -EIO;
> > +	}
> > +
> > +	ret = sensor->fault_handler(st, *val);
> > +	if (ret)
> > +		return ret;
> > +
> > +	*val = sign_extend32((*val) & LTC2983_DATA_MASK,
> > LTC2983_DATA_SIGN_BIT);
> > +	return 0;
> > +}
> > +
> > +static int ltc2983_read_raw(struct iio_dev *indio_dev,
> > +			    struct iio_chan_spec const *chan,
> > +			    int *val, int *val2, long mask)
> > +{
> > +	struct ltc2983_data *st = iio_priv(indio_dev);
> > +	int ret;
> > +
> > +	/* sanity check */
> > +	if (chan->address >= st->num_channels) {
> > +		dev_err(&st->spi->dev, "Invalid chan address:%ld",
> > +							chan->address);
> > +		return -EINVAL;
> > +	}
> > +
> > +	switch (mask) {
> > +	case IIO_CHAN_INFO_RAW:
> > +		mutex_lock(&st->lock);
> > +		ret = ltc2983_chan_read(st, st->sensors[chan->address], 
> > val);
> > +		mutex_unlock(&st->lock);
> > +		return ret ?: IIO_VAL_INT;
> > +	case IIO_CHAN_INFO_SCALE:
> > +		switch (chan->type) {
> > +		case IIO_TEMP:
> > +			/* value in milli degrees */
> > +			*val = 1000;
> > +			/* 2^10 */
> > +			*val2 = 1024;
> > +			return IIO_VAL_FRACTIONAL;
> > +		case IIO_VOLTAGE:
> > +			/* value in millivolt */
> > +			*val = 1000;
> > +			/* 2^21 */
> > +			*val2 = 2097152;
> > +			return IIO_VAL_FRACTIONAL;
> > +		default:
> > +			return -EINVAL;
> > +		}
> > +	}
> > +
> > +	return -EINVAL;
> > +}
> > +
> > +static int ltc2983_reg_access(struct iio_dev *indio_dev,
> > +			      unsigned int reg,
> > +			      unsigned int writeval,
> > +			      unsigned int *readval)
> > +{
> > +	struct ltc2983_data *st = iio_priv(indio_dev);
> > +
> > +	/* check comment in ltc2983_chan_read() */
> > +	if (st->sleep)
> > +		return -EPERM;
> > +
> > +	if (readval)
> > +		return regmap_read(st->regmap, reg, readval);
> > +	else
> > +		return regmap_write(st->regmap, reg, writeval);
> > +}
> > +
> > +static irqreturn_t ltc2983_irq_handler(int irq, void *data)
> > +{
> > +	struct ltc2983_data *st = data;
> > +
> > +	complete(&st->completion);
> 
> This is a rare case where I'm not sure a threaded irq actually
> makes sense.  We may be better off just doing this in a traditional
> top half, rather than spinning up a thread just to set completion.
> 
> > +	return IRQ_HANDLED;
> > +}
> > +
> > +#define LTC2983_CHAN(__type, index, __address) ({ \
> > +	struct iio_chan_spec __chan = { \
> > +		.type = __type, \
> > +		.indexed = 1, \
> > +		.channel = index, \
> > +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> > +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> > +		.address = __address, \
> > +	}; \
> > +	__chan; \
> > +})
> > +
> > +static int ltc2983_parse_dt(struct ltc2983_data *st)
> > +{
> > +	struct device_node *child;
> > +	struct device *dev = &st->spi->dev;
> > +	int ret = 0, chan = 0, channel_avail_mask = 0;
> > +
> > +	if (!of_property_read_bool(dev->of_node, "adi,temperature-
> > celcius"))
> > +		st->temp_farenheit = true;
> > +
> > +	of_property_read_u32(dev->of_node, "adi,mux-delay-config-us",
> > +			     &st->mux_delay_config);
> > +
> > +	of_property_read_u32(dev->of_node, "adi,filter-notch-freq",
> > +			     &st->filter_notch_freq);
> > +
> > +	st->num_channels = of_get_available_child_count(dev->of_node);
> > +	st->sensors = devm_kcalloc(dev, st->num_channels, sizeof(*st-
> > >sensors),
> > +				   GFP_KERNEL);
> > +	if (!st->sensors)
> > +		return -ENOMEM;
> > +
> > +	st->iio_channels = st->num_channels;
> > +	for_each_available_child_of_node(dev->of_node, child) {
> > +		struct ltc2983_sensor sensor;
> > +
> > +		ret = of_property_read_u32(child, "reg", &sensor.chan);
> > +		if (ret) {
> > +			dev_err(dev, "reg property must given for child
> > nodes\n");
> > +			return ret;
> > +		}
> > +
> > +		/* check if we have a valid channel */
> > +		if (sensor.chan < LTC2983_MIN_CHANNELS_NR ||
> > +		    sensor.chan > LTC2983_MAX_CHANNELS_NR) {
> > +			dev_err(dev,
> > +				"chan:%d must be from 1 to 20\n",
> > sensor.chan);
> > +			return -EINVAL;
> > +		} else if (channel_avail_mask & BIT(sensor.chan)) {
> > +			dev_err(dev, "chan:%d already in use\n",
> > sensor.chan);
> > +			return -EINVAL;
> > +		}
> > +
> > +		ret = of_property_read_u32(child, "adi,sensor-type",
> > +					       &sensor.type);
> > +		if (ret) {
> > +			dev_err(dev,
> > +				"adi,sensor-type property must given
> > for child nodes\n");
> > +			return ret;
> > +		}
> > +
> > +		dev_dbg(dev, "Create new sensor, type %u, chann %u",
> > +								sensor.
> > type,
> > +								sensor.
> > chan);
> > +
> > +		if (sensor.type >= LTC2983_SENSOR_THERMOCOUPLE &&
> > +		    sensor.type <= LTC2983_SENSOR_THERMOCOUPLE_CUSTOM)
> > {
> > +			st->sensors[chan] =
> > ltc2983_thermocouple_new(child, st,
> > +								     &s
> > ensor);
> > +		} else if (sensor.type >= LTC2983_SENSOR_RTD &&
> > +			   sensor.type <= LTC2983_SENSOR_RTD_CUSTOM) {
> > +			st->sensors[chan] = ltc2983_rtd_new(child, st,
> > &sensor);
> > +		} else if (sensor.type >= LTC2983_SENSOR_THERMISTOR &&
> > +			   sensor.type <=
> > LTC2983_SENSOR_THERMISTOR_CUSTOM) {
> > +			st->sensors[chan] =
> > ltc2983_thermistor_new(child, st,
> > +								   &sen
> > sor);
> > +		} else if (sensor.type == LTC2983_SENSOR_DIODE) {
> > +			st->sensors[chan] = ltc2983_diode_new(child,
> > st,
> > +							      &sensor);
> > +		} else if (sensor.type ==
> > LTC2983_SENSOR_SENSE_RESISTOR) {
> > +			st->sensors[chan] = ltc2983_r_sense_new(child,
> > st,
> > +								&sensor
> > );
> > +			/* don't add rsense to iio */
> > +			st->iio_channels--;
> > +		} else if (sensor.type == LTC2983_SENSOR_DIRECT_ADC) {
> > +			st->sensors[chan] = ltc2983_adc_new(child, st,
> > &sensor);
> > +		} else {
> > +			dev_err(dev, "Unknown sensor type %d\n",
> > sensor.type);
> > +			return -EINVAL;
> > +		}
> > +
> > +		if (IS_ERR(st->sensors[chan])) {
> > +			dev_err(dev, "Failed to create sensor %ld",
> > +						PTR_ERR(st-
> > >sensors[chan]));
> > +			return PTR_ERR(st->sensors[chan]);
> > +		}
> > +		/* set generic sensor parameters */
> > +		st->sensors[chan]->chan = sensor.chan;
> > +		st->sensors[chan]->type = sensor.type;
> > +
> > +		channel_avail_mask |= BIT(sensor.chan);
> > +		chan++;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static int ltc2983_setup(struct ltc2983_data *st, bool assign_iio)
> > +{
> > +	u32 iio_chan_t = 0, iio_chan_v = 0, chan, iio_idx = 0;
> > +	u32 global_cfg = 0;
> > +	int ret;
> > +	unsigned long time;
> > +
> > +	/* make sure the device is up */
> > +	time = wait_for_completion_timeout(&st->completion,
> > +					    msecs_to_jiffies(250));
> > +
> > +	if (!time) {
> > +		dev_err(&st->spi->dev, "Device startup timed out\n");
> > +		return -ETIMEDOUT;
> > +	}
> > +
> > +	st->iio_chan = devm_kzalloc(&st->spi->dev,
> > +				    st->iio_channels * sizeof(*st-
> > >iio_chan),
> > +				    GFP_KERNEL);
> > +
> > +	if (!st->iio_chan)
> > +		return -ENOMEM;
> > +
> > +	global_cfg = LTC2983_NOTCH_FREQ(st->filter_notch_freq);
> > +	global_cfg |= LTC2983_TEMP_UNITS(st->temp_farenheit);
> > +	regmap_write(st->regmap, LTC2983_GLOBAL_CONFIG_REG,
> > global_cfg);
> > +	regmap_write(st->regmap, LTC2983_MUX_CONFIG_REG, st-
> > >mux_delay_config);
> > +
> > +	for (chan = 0; chan < st->num_channels; chan++) {
> > +		u32 chan_type = 0, *iio_chan;
> > +
> > +		ret = st->sensors[chan]->assign_chan(st, st-
> > >sensors[chan]);
> > +		if (ret)
> > +			return ret;
> > +		/*
> > +		 * The assign_iio flag is necessary for when the device
> > is
> > +		 * coming out of sleep. In that case, we just need to
> > +		 * re-configure the device channels.
> > +		 * We also don't assign iio channels for rsense.
> > +		 */
> > +		if (st->sensors[chan]->type ==
> > LTC2983_SENSOR_SENSE_RESISTOR ||
> > +		    !assign_iio)
> > +			continue;
> > +
> > +		/* assign iio channel */
> > +		if (st->sensors[chan]->type !=
> > LTC2983_SENSOR_DIRECT_ADC) {
> > +			chan_type = IIO_TEMP;
> > +			iio_chan = &iio_chan_t;
> > +		} else {
> > +			chan_type = IIO_VOLTAGE;
> > +			iio_chan = &iio_chan_v;
> > +		}
> > +
> > +		/*
> > +		 * add chan as the iio .address so that, we can
> > directly
> > +		 * reference the sensor given the iio_chan_spec
> > +		 */
> > +		st->iio_chan[iio_idx++] = LTC2983_CHAN(chan_type,
> > (*iio_chan)++,
> > +						       chan);
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static const struct regmap_range ltc2983_reg_ranges[] = {
> > +	regmap_reg_range(LTC2983_STATUS_REG, LTC2983_STATUS_REG),
> > +	regmap_reg_range(LTC2983_TEMP_RES_START_REG,
> > LTC2983_TEMP_RES_END_REG),
> > +	regmap_reg_range(LTC2983_GLOBAL_CONFIG_REG,
> > LTC2983_GLOBAL_CONFIG_REG),
> > +	regmap_reg_range(LTC2983_MULT_CHANNEL_START_REG,
> > +			 LTC2983_MULT_CHANNEL_END_REG),
> > +	regmap_reg_range(LTC2983_MUX_CONFIG_REG,
> > LTC2983_MUX_CONFIG_REG),
> > +	regmap_reg_range(LTC2983_CHAN_ASSIGN_START_REG,
> > +			 LTC2983_CHAN_ASSIGN_END_REG),
> > +	regmap_reg_range(LTC2983_CUST_SENS_TBL_START_REG,
> > +			 LTC2983_CUST_SENS_TBL_END_REG),
> > +};
> > +
> > +static const struct regmap_access_table ltc2983_reg_table = {
> > +	.yes_ranges = ltc2983_reg_ranges,
> > +	.n_yes_ranges = ARRAY_SIZE(ltc2983_reg_ranges),
> > +};
> > +
> > +/*
> > + *  The reg_bits are actually 12 but the device needs the first
> > *complete*
> > + *  byte for the command (R/W).
> > + */
> > +static const struct regmap_config ltc2983_regmap_config = {
> > +	.reg_bits = 24,
> > +	.val_bits = 8,
> > +	.wr_table = &ltc2983_reg_table,
> > +	.rd_table = &ltc2983_reg_table,
> > +	.read_flag_mask = GENMASK(1, 0),
> > +	.write_flag_mask = BIT(1),
> > +};
> > +
> > +static const struct  iio_info ltc2983_iio_info = {
> > +	.read_raw = ltc2983_read_raw,
> > +	.debugfs_reg_access = ltc2983_reg_access,
> > +};
> > +
> > +static int ltc2983_probe(struct spi_device *spi)
> > +{
> > +	struct ltc2983_data *st;
> > +	struct iio_dev *indio_dev;
> > +	const char *name = spi_get_device_id(spi)->name;
> > +	int ret;
> > +
> > +	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
> > +	if (!indio_dev)
> > +		return -ENOMEM;
> > +
> > +	st = iio_priv(indio_dev);
> > +
> > +	st->regmap = devm_regmap_init_spi(spi, &ltc2983_regmap_config);
> > +	if (IS_ERR(st->regmap)) {
> > +		dev_err(&spi->dev, "Failed to initialize regmap\n");
> > +		return PTR_ERR(st->regmap);
> > +	}
> > +
> > +	mutex_init(&st->lock);
> > +	init_completion(&st->completion);
> > +	st->spi = spi;
> > +	spi_set_drvdata(spi, st);
> > +
> > +	ret = ltc2983_parse_dt(st);
> > +	if (ret)
> > +		return ret;
> > +	/*
> > +	 * let's request the irq now so it is used to sync the device
> > +	 * startup in ltc2983_setup()
> > +	 */
> > +	ret = devm_request_threaded_irq(&spi->dev, spi->irq, NULL,
> > +					ltc2983_irq_handler,
> > IRQF_ONESHOT |
> > +					IRQF_TRIGGER_RISING, name, st);
> > +	if (ret) {
> > +		dev_err(&spi->dev, "failed to request an irq, %d",
> > ret);
> > +		return ret;
> > +	}
> > +
> > +	ret = ltc2983_setup(st, true);
> > +	if (ret)
> > +		return ret;
> > +
> > +	indio_dev->dev.parent = &spi->dev;
> > +	indio_dev->name = name;
> > +	indio_dev->num_channels = st->iio_channels;
> > +	indio_dev->channels = st->iio_chan;
> > +	indio_dev->modes = INDIO_DIRECT_MODE;
> > +	indio_dev->info = &ltc2983_iio_info;
> > +
> > +	return devm_iio_device_register(&spi->dev, indio_dev);
> > +}
> > +
> > +static int __maybe_unused ltc2983_resume(struct device *dev)
> > +{
> > +	struct ltc2983_data *st = spi_get_drvdata(to_spi_device(dev));
> > +	int ret;
> > +
> > +	mutex_lock(&st->lock);
> > +	/* dummy read to bring the device out of sleep */
> > +	regmap_read(st->regmap, LTC2983_STATUS_REG, &ret);
> > +	/* we need to re-assign the channels */
> > +	ret = ltc2983_setup(st, false);
> > +	st->sleep = false;
> > +	mutex_unlock(&st->lock);
> > +
> > +	return ret;
> > +}
> > +
> > +static int __maybe_unused ltc2983_suspend(struct device *dev)
> > +{
> > +	struct ltc2983_data *st = spi_get_drvdata(to_spi_device(dev));
> > +	int ret;
> > +
> > +	mutex_lock(&st->lock);
> > +	ret = regmap_write(st->regmap, LTC2983_STATUS_REG,
> > LTC2983_SLEEP);
> > +	st->sleep = true;
> > +	mutex_unlock(&st->lock);
> > +
> > +	return ret;
> > +}
> > +
> > +static SIMPLE_DEV_PM_OPS(ltc2983_pm_ops, ltc2983_suspend,
> > ltc2983_resume);
> > +
> > +static const struct spi_device_id ltc2983_id_table[] = {
> > +	{ "ltc2983" },
> > +	{},
> > +};
> > +MODULE_DEVICE_TABLE(spi, ltc2983_id_table);
> > +
> > +static const struct of_device_id ltc2983_of_match[] = {
> > +	{ .compatible = "adi,ltc2983" },
> > +	{},
> > +};
> > +MODULE_DEVICE_TABLE(of, ltc2983_id_table);
> > +
> > +static struct spi_driver ltc2983_driver = {
> > +	.driver = {
> > +		.name = "ltc2983",
> > +		.of_match_table = ltc2983_of_match,
> > +		.pm = &ltc2983_pm_ops,
> > +	},
> > +	.probe = ltc2983_probe,
> > +	.id_table = ltc2983_id_table,
> > +};
> > +
> > +module_spi_driver(ltc2983_driver);
> > +
> > +MODULE_AUTHOR("Nuno Sa <[e-mail]>");
> > +MODULE_DESCRIPTION("Analog Devices LTC2983 SPI Temperature
> > sensors");
> > +MODULE_LICENSE("GPL");

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index f0c03740b9fb..14a256e785ca 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9491,6 +9491,13 @@  S:	Maintained
 F:	Documentation/devicetree/bindings/iio/dac/ltc1660.txt
 F:	drivers/iio/dac/ltc1660.c
 
+LTC2983 IIO TEMPERATURE DRIVER
+M:	Nuno Sá <[e-mail]>
+W:	http://ez.analog.com/community/linux-device-drivers
+L:	[e-mail]
+S:	Supported
+F:	drivers/iio/temperature/ltc2983.c
+
 LTC4261 HARDWARE MONITOR DRIVER
 M:	Guenter Roeck <[e-mail]>
 L:	[e-mail]
diff --git a/drivers/iio/temperature/Kconfig b/drivers/iio/temperature/Kconfig
index 737faa0901fe..04b5a67b593c 100644
--- a/drivers/iio/temperature/Kconfig
+++ b/drivers/iio/temperature/Kconfig
@@ -4,6 +4,16 @@ 
 #
 menu "Temperature sensors"
 
+config LTC2983
+	tristate "Analog Devices Multi-Sensor Digital Temperature Measurement System"
+	depends on SPI
+	help
+	  Say yes here to build support for the LTC2983 Multi-Sensor
+	  high accuracy digital temperature measurement system.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called ltc2983.
+
 config MAXIM_THERMOCOUPLE
 	tristate "Maxim thermocouple sensors"
 	depends on SPI
diff --git a/drivers/iio/temperature/Makefile b/drivers/iio/temperature/Makefile
index baca4776ca0d..d6b850b0cf63 100644
--- a/drivers/iio/temperature/Makefile
+++ b/drivers/iio/temperature/Makefile
@@ -3,6 +3,7 @@ 
 # Makefile for industrial I/O temperature drivers
 #
 
+obj-$(CONFIG_LTC2983) += ltc2983.o
 obj-$(CONFIG_HID_SENSOR_TEMP) += hid-sensor-temperature.o
 obj-$(CONFIG_MAXIM_THERMOCOUPLE) += maxim_thermocouple.o
 obj-$(CONFIG_MAX31856) += max31856.o
diff --git a/drivers/iio/temperature/ltc2983.c b/drivers/iio/temperature/ltc2983.c
new file mode 100644
index 000000000000..7c159da9f183
--- /dev/null
+++ b/drivers/iio/temperature/ltc2983.c
@@ -0,0 +1,1436 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Analog Devices LTC2983 Multi-Sensor Digital Temperature Measurement System
+ * driver
+ *
+ * Copyright 2019 Analog Devices Inc.
+ */
+#include <linux/bitfield.h>
+#include <linux/completion.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/iio/iio.h>
+#include <linux/interrupt.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/of_gpio.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+
+/* register map */
+#define LTC2983_STATUS_REG			0x0000
+#define LTC2983_TEMP_RES_START_REG		0x0010
+#define LTC2983_TEMP_RES_END_REG		0x005F
+#define LTC2983_GLOBAL_CONFIG_REG		0x00F0
+#define LTC2983_MULT_CHANNEL_START_REG		0x00F4
+#define LTC2983_MULT_CHANNEL_END_REG		0x00F7
+#define LTC2983_MUX_CONFIG_REG			0x00FF
+#define LTC2983_CHAN_ASSIGN_START_REG		0x0200
+#define LTC2983_CHAN_ASSIGN_END_REG		0x024F
+#define LTC2983_CUST_SENS_TBL_START_REG		0x0250
+#define LTC2983_CUST_SENS_TBL_END_REG		0x03CF
+
+#define LTC2983_DIFFERENTIAL_CHAN_MIN		2
+#define LTC2983_MAX_CHANNELS_NR			20
+#define LTC2983_MIN_CHANNELS_NR			1
+#define LTC2983_SLEEP				0x97
+#define LTC2983_CUSTOM_STEINHART_SIZE		24
+#define LTC2983_CUSTOM_SENSOR_ENTRY_SZ		6
+#define LTC2983_CUSTOM_STEINHART_ENTRY_SZ	4
+
+#define LTC2983_CHAN_START_ADDR(chan) \
+			(((chan - 1) * 4) + LTC2983_CHAN_ASSIGN_START_REG)
+#define LTC2983_CHAN_RES_ADDR(chan) \
+			(((chan - 1) * 4) + LTC2983_TEMP_RES_START_REG)
+#define LTC2983_THERMOCOUPLE_DIFF_MASK		BIT(3)
+#define LTC2983_THERMISTOR_DIFF_MASK		BIT(2)
+#define LTC2983_DIODE_DIFF_MASK			BIT(2)
+#define LTC2983_RTD_4_WIRE_MASK			BIT(3)
+#define LTC2983_RTD_ROTATION_MASK		BIT(1)
+#define LTC2983_RTD_KELVIN_R_SENSE_MASK		GENMASK(3, 2)
+
+#define LTC2983_COMMON_HARD_FAULT_MASK	GENMASK(31, 30)
+#define LTC2983_COMMON_SOFT_FAULT_MASK	GENMASK(27, 25)
+
+#define	LTC2983_STATUS_START_MASK	BIT(7)
+#define	LTC2983_STATUS_START(x)		FIELD_PREP(LTC2983_STATUS_START_MASK, x)
+
+#define	LTC2983_STATUS_CHAN_SEL_MASK	GENMASK(4, 0)
+#define	LTC2983_STATUS_CHAN_SEL(x) \
+				FIELD_PREP(LTC2983_STATUS_CHAN_SEL_MASK, x)
+
+#define LTC2983_TEMP_UNITS_MASK		BIT(2)
+#define LTC2983_TEMP_UNITS(x)		FIELD_PREP(LTC2983_TEMP_UNITS_MASK, x)
+
+#define LTC2983_NOTCH_FREQ_MASK		GENMASK(1, 0)
+#define LTC2983_NOTCH_FREQ(x)		FIELD_PREP(LTC2983_NOTCH_FREQ_MASK, x)
+
+#define LTC2983_RES_VALID_MASK		BIT(24)
+#define LTC2983_DATA_MASK		GENMASK(23, 0)
+#define LTC2983_DATA_SIGN_BIT		23
+
+#define LTC2983_CHAN_TYPE_MASK		GENMASK(31, 27)
+#define LTC2983_CHAN_TYPE(x)		FIELD_PREP(LTC2983_CHAN_TYPE_MASK, x)
+
+/* cold junction for thermocouples and rsense for rtd's and thermistor's */
+#define LTC2983_CHAN_ASSIGN_MASK	GENMASK(26, 22)
+#define LTC2983_CHAN_ASSIGN(x)		FIELD_PREP(LTC2983_CHAN_ASSIGN_MASK, x)
+
+#define LTC2983_CUSTOM_LEN_MASK		GENMASK(5, 0)
+#define LTC2983_CUSTOM_LEN(x)		FIELD_PREP(LTC2983_CUSTOM_LEN_MASK, x)
+
+#define LTC2983_CUSTOM_ADDR_MASK	GENMASK(11, 6)
+#define LTC2983_CUSTOM_ADDR(x)		FIELD_PREP(LTC2983_CUSTOM_ADDR_MASK, x)
+
+#define LTC2983_THERMOCOUPLE_CFG_MASK	GENMASK(21, 18)
+#define LTC2983_THERMOCOUPLE_CFG(x) \
+				FIELD_PREP(LTC2983_THERMOCOUPLE_CFG_MASK, x)
+#define LTC2983_THERMOCOUPLE_HARD_FAULT_MASK	GENMASK(31, 29)
+#define LTC2983_THERMOCOUPLE_SOFT_FAULT_MASK	GENMASK(28, 25)
+
+#define LTC2983_RTD_CFG_MASK		GENMASK(21, 18)
+#define LTC2983_RTD_CFG(x)		FIELD_PREP(LTC2983_RTD_CFG_MASK, x)
+#define LTC2983_RTD_EXC_CURRENT_MASK	GENMASK(17, 14)
+#define LTC2983_RTD_EXC_CURRENT(x) \
+				FIELD_PREP(LTC2983_RTD_EXC_CURRENT_MASK, x)
+#define LTC2983_RTD_CURVE_MASK		GENMASK(13, 12)
+#define LTC2983_RTD_CURVE(x)		FIELD_PREP(LTC2983_RTD_CURVE_MASK, x)
+
+#define LTC2983_THERMISTOR_CFG_MASK	GENMASK(21, 19)
+#define LTC2983_THERMISTOR_CFG(x) \
+				FIELD_PREP(LTC2983_THERMISTOR_CFG_MASK, x)
+#define LTC2983_THERMISTOR_EXC_CURRENT_MASK	GENMASK(18, 15)
+#define LTC2983_THERMISTOR_EXC_CURRENT(x) \
+			FIELD_PREP(LTC2983_THERMISTOR_EXC_CURRENT_MASK, x)
+
+#define LTC2983_DIODE_CFG_MASK		GENMASK(26, 24)
+#define LTC2983_DIODE_CFG(x)		FIELD_PREP(LTC2983_DIODE_CFG_MASK, x)
+#define LTC2983_DIODE_EXC_CURRENT_MASK	GENMASK(23, 22)
+#define LTC2983_DIODE_EXC_CURRENT(x) \
+				FIELD_PREP(LTC2983_DIODE_EXC_CURRENT_MASK, x)
+#define LTC2983_DIODE_IDEAL_FACTOR_MASK	GENMASK(21, 0)
+#define LTC2983_DIODE_IDEAL_FACTOR(x) \
+				FIELD_PREP(LTC2983_DIODE_IDEAL_FACTOR_MASK, x)
+
+#define LTC2983_R_SENSE_VAL_MASK	GENMASK(26, 0)
+#define LTC2983_R_SENSE_VAL(x)		FIELD_PREP(LTC2983_R_SENSE_VAL_MASK, x)
+
+#define LTC2983_ADC_SINGLE_ENDED_MASK	BIT(26)
+#define LTC2983_ADC_SINGLE_ENDED(x) \
+				FIELD_PREP(LTC2983_ADC_SINGLE_ENDED_MASK, x)
+
+enum {
+	LTC2983_SENSOR_THERMOCOUPLE = 1,
+	LTC2983_SENSOR_THERMOCOUPLE_CUSTOM = 9,
+	LTC2983_SENSOR_RTD = 10,
+	LTC2983_SENSOR_RTD_CUSTOM = 18,
+	LTC2983_SENSOR_THERMISTOR = 19,
+	LTC2983_SENSOR_THERMISTOR_STEINHART = 26,
+	LTC2983_SENSOR_THERMISTOR_CUSTOM = 27,
+	LTC2983_SENSOR_DIODE = 28,
+	LTC2983_SENSOR_SENSE_RESISTOR = 29,
+	LTC2983_SENSOR_DIRECT_ADC = 30,
+};
+
+#define to_thermocouple(_sensor) \
+		container_of(_sensor, struct ltc2983_thermocouple, sensor)
+
+#define to_rtd(_sensor) \
+		container_of(_sensor, struct ltc2983_rtd, sensor)
+
+#define to_thermistor(_sensor) \
+		container_of(_sensor, struct ltc2983_thermistor, sensor)
+
+#define to_diode(_sensor) \
+		container_of(_sensor, struct ltc2983_diode, sensor)
+
+#define to_rsense(_sensor) \
+		container_of(_sensor, struct ltc2983_rsense, sensor)
+
+#define to_adc(_sensor) \
+		container_of(_sensor, struct ltc2983_adc, sensor)
+
+struct ltc2983_data {
+	struct regmap *regmap;
+	struct spi_device *spi;
+	struct mutex lock;
+	struct completion completion;
+	struct iio_chan_spec *iio_chan;
+	struct ltc2983_sensor **sensors;
+	u32 mux_delay_config;
+	u32 filter_notch_freq;
+	u16 custom_table_size;
+	u8 num_channels;
+	u8 iio_channels;
+	bool temp_farenheit;
+	bool sleep;
+};
+
+struct ltc2983_sensor {
+	int (*fault_handler)(const struct ltc2983_data *st, const u32 result);
+	int (*assign_chan)(struct ltc2983_data *st,
+			   const struct ltc2983_sensor *sensor);
+	/* specifies the sensor channel */
+	u32 chan;
+	/* sensor type */
+	u32 type;
+};
+
+struct ltc2983_custom_sensor {
+	/* raw table sensor data */
+	u8 *table;
+	size_t size;
+	/* address offset */
+	s8 offset;
+	bool is_steinhart;
+};
+
+struct ltc2983_thermocouple {
+	struct ltc2983_sensor sensor;
+	struct ltc2983_custom_sensor *custom;
+	u32 sensor_config;
+	u32 cold_junction_chan;
+};
+
+struct ltc2983_rtd {
+	struct ltc2983_sensor sensor;
+	struct ltc2983_custom_sensor *custom;
+	u32 sensor_config;
+	u32 r_sense_chan;
+	u32 excitation_current;
+	u32 rtd_curve;
+};
+
+struct ltc2983_thermistor {
+	struct ltc2983_sensor sensor;
+	struct ltc2983_custom_sensor *custom;
+	u32 sensor_config;
+	u32 r_sense_chan;
+	u32 excitation_current;
+};
+
+struct ltc2983_diode {
+	struct ltc2983_sensor sensor;
+	u32 sensor_config;
+	u32 excitation_current;
+	u32 ideal_factor_value;
+};
+
+struct ltc2983_rsense {
+	struct ltc2983_sensor sensor;
+	u32 r_sense_val;
+};
+
+struct ltc2983_adc {
+	struct ltc2983_sensor sensor;
+	bool single_ended;
+};
+
+/*
+ * Convert to Q format numbers. These number's are integers where
+ * the number of integer and fractional bits are specified. The resolution
+ * is given by 1/@resolution and tell us the number of fractional bits. For
+ * instance a resolution of 2^-10 means we have 10 fractional bits.
+ */
+static u32 __convert_to_raw(const u64 val, const u32 resolution)
+{
+	u64 __res = val * resolution;
+
+	/* all values are multiplied by 1000000 to remove the fraction */
+	do_div(__res, 1000000);
+
+	return __res;
+}
+
+static u32 __convert_to_raw_sign(const u64 val, const u32 resolution)
+{
+	s64 __res = -(s32)val;
+
+	__res = __convert_to_raw(__res, resolution);
+
+	return (u32)-__res;
+}
+
+static int __ltc2983_fault_handler(const struct ltc2983_data *st,
+				   const u32 result, const u32 hard_mask,
+				   const u32 soft_mask)
+{
+	const struct device *dev = &st->spi->dev;
+
+	if (result & hard_mask) {
+		dev_err(dev, "Invalid conversion: Sensor HARD fault\n");
+		return -EIO;
+	} else if (result & soft_mask) {
+		/* just print a warning */
+		dev_warn(dev, "Suspicious conversion: Sensor SOFT fault\n");
+	}
+
+	return 0;
+}
+
+static int __ltc2983_chan_assign_common(const struct ltc2983_data *st,
+					const struct ltc2983_sensor *sensor,
+					u32 chan_val)
+{
+	u32 reg = LTC2983_CHAN_START_ADDR(sensor->chan);
+	__be32 __chan_val;
+
+	chan_val |= LTC2983_CHAN_TYPE(sensor->type);
+	dev_dbg(&st->spi->dev, "Assign reg:0x%04X, val:0x%08X\n", reg,
+								chan_val);
+	__chan_val = cpu_to_be32(chan_val);
+	return regmap_bulk_write(st->regmap, reg, &__chan_val,
+				 sizeof(__chan_val));
+}
+
+static int __ltc2983_chan_custom_sensor_assign(struct ltc2983_data *st,
+					  struct ltc2983_custom_sensor *custom,
+					  u32 *chan_val)
+{
+	u32 reg;
+	u8 mult = custom->is_steinhart ? LTC2983_CUSTOM_STEINHART_ENTRY_SZ :
+		LTC2983_CUSTOM_SENSOR_ENTRY_SZ;
+	const struct device *dev = &st->spi->dev;
+	/*
+	 * custom->size holds the raw size of the table. However, when
+	 * configuring the sensor channel, we must write the number of
+	 * entries of the table minus 1. For steinhart sensors 0 is written
+	 * since the size is constant!
+	 */
+	const u8 len = custom->is_steinhart ? 0 :
+		(custom->size / LTC2983_CUSTOM_SENSOR_ENTRY_SZ) - 1;
+	/*
+	 * Check if the offset was assigned already. It should be for steinhart
+	 * sensors. When coming from sleep, it should be assigned for all.
+	 */
+	if (custom->offset < 0) {
+		/*
+		 * This needs to be done again here because, from the moment
+		 * when this test was done (successfully) for this custom
+		 * sensor, a steinhart sensor might have been added changing
+		 * custom_table_size...
+		 */
+		if (st->custom_table_size + custom->size >
+		    (LTC2983_CUST_SENS_TBL_END_REG -
+		     LTC2983_CUST_SENS_TBL_START_REG) + 1) {
+			dev_err(dev,
+				"Not space left(%d) for new custom sensor(%zu)",
+							st->custom_table_size,
+							custom->size);
+			return -EINVAL;
+		}
+
+		custom->offset = st->custom_table_size /
+					LTC2983_CUSTOM_SENSOR_ENTRY_SZ;
+		st->custom_table_size += custom->size;
+	}
+
+	reg = (custom->offset * mult) + LTC2983_CUST_SENS_TBL_START_REG;
+
+	*chan_val |= LTC2983_CUSTOM_LEN(len);
+	*chan_val |= LTC2983_CUSTOM_ADDR(custom->offset);
+	dev_dbg(dev, "Assign custom sensor, reg:0x%04X, off:%d, sz:%zu",
+							reg, custom->offset,
+							custom->size);
+	/* write custom sensor table */
+	return regmap_bulk_write(st->regmap, reg, custom->table, custom->size);
+}
+
+static struct ltc2983_custom_sensor *__ltc2983_custom_sensor_new(
+						struct ltc2983_data *st,
+						const struct device_node *np,
+						const bool is_steinhart,
+						const u32 resolution,
+						const bool has_signed)
+{
+	struct ltc2983_custom_sensor *new_custom;
+	u8 index, n_entries, tbl = 0;
+	struct device *dev = &st->spi->dev;
+	/*
+	 * For custom steinhart, the full u32 is taken. For all the others
+	 * the MSB is discarded.
+	 */
+	const u8 n_size = (is_steinhart == true) ? 4 : 3;
+
+	n_entries = of_property_count_elems_of_size(np, "adi,custom-sensor",
+						sizeof(u64));
+	/* n_entries must be an even number */
+	if (!n_entries || (n_entries % 2) != 0) {
+		dev_err(dev, "Number of entries either 0 or not even\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	new_custom = devm_kzalloc(dev, sizeof(*new_custom), GFP_KERNEL);
+	if (!new_custom)
+		return ERR_PTR(-ENOMEM);
+
+	new_custom->size = n_entries * n_size;
+	/* check Steinhart size */
+	if (is_steinhart && new_custom->size != LTC2983_CUSTOM_STEINHART_SIZE) {
+		dev_err(dev, "Steinhart sensors size(%zu) must be 24",
+							new_custom->size);
+		return ERR_PTR(-EINVAL);
+	}
+	/* Check space on the table. */
+	if (st->custom_table_size + new_custom->size >
+	    (LTC2983_CUST_SENS_TBL_END_REG -
+	     LTC2983_CUST_SENS_TBL_START_REG) + 1) {
+		dev_err(dev, "No space left(%d) for new custom sensor(%zu)",
+				st->custom_table_size, new_custom->size);
+		return ERR_PTR(-EINVAL);
+	}
+
+	/* allocate the table */
+	new_custom->table = devm_kzalloc(dev, new_custom->size, GFP_KERNEL);
+	if (!new_custom->table)
+		return ERR_PTR(-ENOMEM);
+
+	for (index = 0; index < n_entries; index++) {
+		u64 temp = 0, j;
+
+		of_property_read_u64_index(np, "adi,custom-sensor", index,
+					   &temp);
+		/*
+		 * Steinhart sensors are configured with raw values in the
+		 * devicetree. For the other sensors we must convert the
+		 * value to raw. The odd index's correspond to temperarures
+		 * and always have 1/1024 of resolution. Temperatures also
+		 * come in kelvin, so signed values is not possible
+		 */
+		if (!is_steinhart) {
+			if ((index % 2) != 0)
+				temp = __convert_to_raw(temp, 1024);
+			else if (has_signed && (s64)temp < 0)
+				temp = __convert_to_raw_sign(temp, resolution);
+			else
+				temp = __convert_to_raw(temp, resolution);
+		}
+
+		for (j = 0; j < n_size; j++)
+			new_custom->table[tbl++] =
+				temp >> (8 * (n_size - j - 1));
+	}
+
+	new_custom->is_steinhart = is_steinhart;
+	/*
+	 * This is done to first add all the steinhart sensors to the table,
+	 * in order to maximize the table usage. If we mix adding steinhart
+	 * with the other sensors, we might have to do some roundup to make
+	 * sure that sensor_addr - 0x250(start address) is a multiple of 4
+	 * (for steinhart), and a multiple of 6 for all the other sensors.
+	 * Since we have const 24 bytes for steinhart sensors and 24 is
+	 * also a multiple of 6, we guarantee that the first non-steinhart
+	 * sensor will sit in a correct address without the need of filling
+	 * addresses.
+	 */
+	if (is_steinhart) {
+		new_custom->offset = st->custom_table_size /
+					LTC2983_CUSTOM_STEINHART_ENTRY_SZ;
+		st->custom_table_size += new_custom->size;
+	} else {
+		/* mark as unset. This is checked later on the assign phase */
+		new_custom->offset = -1;
+	}
+
+	return new_custom;
+}
+
+static int ltc2983_thermocouple_fault_handler(const struct ltc2983_data *st,
+					      const u32 result)
+{
+	return __ltc2983_fault_handler(st, result,
+				       LTC2983_THERMOCOUPLE_HARD_FAULT_MASK,
+				       LTC2983_THERMOCOUPLE_SOFT_FAULT_MASK);
+}
+
+static int ltc2983_common_fault_handler(const struct ltc2983_data *st,
+					const u32 result)
+{
+	return __ltc2983_fault_handler(st, result,
+				       LTC2983_COMMON_HARD_FAULT_MASK,
+				       LTC2983_COMMON_SOFT_FAULT_MASK);
+}
+
+static int ltc2983_thermocouple_assign_chan(struct ltc2983_data *st,
+				const struct ltc2983_sensor *sensor)
+{
+	struct ltc2983_thermocouple *thermo = to_thermocouple(sensor);
+	u32 chan_val;
+
+	chan_val = LTC2983_CHAN_ASSIGN(thermo->cold_junction_chan);
+	chan_val |= LTC2983_THERMOCOUPLE_CFG(thermo->sensor_config);
+
+	if (thermo->custom) {
+		int ret;
+
+		ret = __ltc2983_chan_custom_sensor_assign(st, thermo->custom,
+							  &chan_val);
+		if (ret)
+			return ret;
+	}
+	return __ltc2983_chan_assign_common(st, sensor, chan_val);
+}
+
+static int ltc2983_rtd_assign_chan(struct ltc2983_data *st,
+				   const struct ltc2983_sensor *sensor)
+{
+	struct ltc2983_rtd *rtd = to_rtd(sensor);
+	u32 chan_val;
+
+	chan_val = LTC2983_CHAN_ASSIGN(rtd->r_sense_chan);
+	chan_val |= LTC2983_RTD_CFG(rtd->sensor_config);
+	chan_val |= LTC2983_RTD_EXC_CURRENT(rtd->excitation_current);
+	chan_val |= LTC2983_RTD_CURVE(rtd->rtd_curve);
+
+	if (rtd->custom) {
+		int ret;
+
+		ret = __ltc2983_chan_custom_sensor_assign(st, rtd->custom,
+							  &chan_val);
+		if (ret)
+			return ret;
+	}
+	return __ltc2983_chan_assign_common(st, sensor, chan_val);
+}
+
+static int ltc2983_thermistor_assign_chan(struct ltc2983_data *st,
+					  const struct ltc2983_sensor *sensor)
+{
+	struct ltc2983_thermistor *thermistor = to_thermistor(sensor);
+	u32 chan_val;
+
+	chan_val = LTC2983_CHAN_ASSIGN(thermistor->r_sense_chan);
+	chan_val |= LTC2983_THERMISTOR_CFG(thermistor->sensor_config);
+	chan_val |=
+		LTC2983_THERMISTOR_EXC_CURRENT(thermistor->excitation_current);
+
+	if (thermistor->custom) {
+		int ret;
+
+		ret = __ltc2983_chan_custom_sensor_assign(st,
+							  thermistor->custom,
+							  &chan_val);
+		if (ret)
+			return ret;
+	}
+	return __ltc2983_chan_assign_common(st, sensor, chan_val);
+}
+
+static int ltc2983_diode_assign_chan(struct ltc2983_data *st,
+				     const struct ltc2983_sensor *sensor)
+{
+	struct ltc2983_diode *diode = to_diode(sensor);
+	u32 chan_val;
+
+	chan_val = LTC2983_DIODE_CFG(diode->sensor_config);
+	chan_val |= LTC2983_DIODE_EXC_CURRENT(diode->excitation_current);
+	chan_val |= LTC2983_DIODE_IDEAL_FACTOR(diode->ideal_factor_value);
+
+	return __ltc2983_chan_assign_common(st, sensor, chan_val);
+}
+
+static int ltc2983_r_sense_assign_chan(struct ltc2983_data *st,
+				       const struct ltc2983_sensor *sensor)
+{
+	struct ltc2983_rsense *rsense = to_rsense(sensor);
+	u32 chan_val;
+
+	chan_val = LTC2983_R_SENSE_VAL(rsense->r_sense_val);
+
+	return __ltc2983_chan_assign_common(st, sensor, chan_val);
+}
+
+static int ltc2983_adc_assign_chan(struct ltc2983_data *st,
+				   const struct ltc2983_sensor *sensor)
+{
+	struct ltc2983_adc *adc = to_adc(sensor);
+	u32 chan_val;
+
+	chan_val = LTC2983_ADC_SINGLE_ENDED(adc->single_ended);
+
+	return __ltc2983_chan_assign_common(st, sensor, chan_val);
+}
+
+static struct ltc2983_sensor *ltc2983_thermocouple_new(
+					const struct device_node *child,
+					struct ltc2983_data *st,
+					const struct ltc2983_sensor *sensor)
+{
+	struct ltc2983_thermocouple *thermo;
+	struct device_node *phandle;
+
+	thermo = devm_kzalloc(&st->spi->dev, sizeof(*thermo), GFP_KERNEL);
+	if (!thermo)
+		return ERR_PTR(-ENOMEM);
+
+	of_property_read_u32(child, "adi,sensor-config",
+				 &thermo->sensor_config);
+	/* validate channel index */
+	if (!(thermo->sensor_config & LTC2983_THERMOCOUPLE_DIFF_MASK) &&
+	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
+		dev_err(&st->spi->dev,
+			"Invalid chann:%d for differential thermocouple",
+								sensor->chan);
+		return ERR_PTR(-EINVAL);
+	}
+
+	phandle = of_parse_phandle(child, "adi,cold-junction-handle", 0);
+	if (phandle) {
+		int ret;
+
+		ret = of_property_read_u32(phandle, "reg",
+					   &thermo->cold_junction_chan);
+		if (ret) {
+			/*
+			 * This would be catched later but we can just return
+			 * the error right away.
+			 */
+			dev_err(&st->spi->dev, "Property reg must be given\n");
+			of_node_put(phandle);
+			return ERR_PTR(-EINVAL);
+		}
+	}
+
+	/* check custom sensor */
+	if (sensor->type == LTC2983_SENSOR_THERMOCOUPLE_CUSTOM) {
+		thermo->custom = __ltc2983_custom_sensor_new(st, child, false,
+							     16384, true);
+		if (IS_ERR(thermo->custom)) {
+			of_node_put(phandle);
+			return ERR_CAST(thermo->custom);
+		}
+	}
+
+	/* set common parameters */
+	thermo->sensor.fault_handler = ltc2983_thermocouple_fault_handler;
+	thermo->sensor.assign_chan = ltc2983_thermocouple_assign_chan;
+
+	of_node_put(phandle);
+	return &thermo->sensor;
+}
+
+static struct ltc2983_sensor *ltc2983_rtd_new(const struct device_node *child,
+					  struct ltc2983_data *st,
+					  const struct ltc2983_sensor *sensor)
+{
+	struct ltc2983_rtd *rtd;
+	int ret = 0;
+	struct device *dev = &st->spi->dev;
+	struct device_node *phandle;
+	u32 excitation_current = 0;
+
+	rtd = devm_kzalloc(dev, sizeof(*rtd), GFP_KERNEL);
+	if (!rtd)
+		return ERR_PTR(-ENOMEM);
+
+	phandle = of_parse_phandle(child, "adi,rsense-handle", 0);
+	if (!phandle) {
+		dev_err(dev, "Property adi,rsense-handle missing or invalid");
+		return ERR_PTR(-EINVAL);
+	}
+
+	ret = of_property_read_u32(phandle, "reg", &rtd->r_sense_chan);
+	if (ret) {
+		dev_err(dev, "Property reg must be given\n");
+		goto fail;
+	}
+
+	of_property_read_u32(child, "adi,sensor-config", &rtd->sensor_config);
+	/*
+	 * rtd channel indexes are a bit more complicated to validate.
+	 * For 4wire RTD with rotation, the channel selection cannot be
+	 * >=19 since the chann + 1 is used in this configuration.
+	 * For 4wire RTDs with kelvin rsense, the rsense channel cannot be
+	 * <=1 since chanel - 1 and channel - 2 are used.
+	 */
+	if (rtd->sensor_config & LTC2983_RTD_4_WIRE_MASK) {
+		/* 4-wire */
+		u8 min = LTC2983_DIFFERENTIAL_CHAN_MIN,
+			max = LTC2983_MAX_CHANNELS_NR;
+
+		if (rtd->sensor_config & LTC2983_RTD_ROTATION_MASK)
+			max = LTC2983_MAX_CHANNELS_NR - 1;
+
+		if (((rtd->sensor_config & LTC2983_RTD_KELVIN_R_SENSE_MASK)
+		     == LTC2983_RTD_KELVIN_R_SENSE_MASK) &&
+		    (rtd->r_sense_chan <=  min)) {
+			/* kelvin rsense*/
+			dev_err(dev,
+				"Invalid rsense chann:%d to use in kelvin rsense",
+							rtd->r_sense_chan);
+
+			ret = -EINVAL;
+			goto fail;
+		}
+
+		if (sensor->chan < min || sensor->chan > max) {
+			dev_err(dev, "Invalid chann:%d for the rtd config",
+								sensor->chan);
+
+			ret = -EINVAL;
+			goto fail;
+		}
+	} else {
+		/* same as differential case */
+		if (sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
+			dev_err(&st->spi->dev,
+				"Invalid chann:%d for RTD", sensor->chan);
+
+			ret = -EINVAL;
+			goto fail;
+		}
+	}
+
+	/* check custom sensor */
+	if (sensor->type == LTC2983_SENSOR_RTD_CUSTOM) {
+		rtd->custom = __ltc2983_custom_sensor_new(st, child, false,
+							  2048, false);
+		if (IS_ERR(rtd->custom)) {
+			of_node_put(phandle);
+			return ERR_CAST(rtd->custom);
+		}
+	}
+
+	/* set common parameters */
+	rtd->sensor.fault_handler = ltc2983_common_fault_handler;
+	rtd->sensor.assign_chan = ltc2983_rtd_assign_chan;
+
+	ret = of_property_read_u32(child, "adi,excitation-current-microamp",
+				   &excitation_current);
+	if (ret) {
+		/* default to 5uA */
+		rtd->excitation_current = 1;
+	} else {
+		switch (excitation_current) {
+		case 5:
+			rtd->excitation_current = 0x01;
+			break;
+		case 10:
+			rtd->excitation_current = 0x02;
+			break;
+		case 25:
+			rtd->excitation_current = 0x03;
+			break;
+		case 50:
+			rtd->excitation_current = 0x04;
+			break;
+		case 100:
+			rtd->excitation_current = 0x05;
+			break;
+		case 250:
+			rtd->excitation_current = 0x06;
+			break;
+		case 500:
+			rtd->excitation_current = 0x07;
+			break;
+		case 1000:
+			rtd->excitation_current = 0x08;
+			break;
+		default:
+			dev_err(&st->spi->dev,
+				"Invalid value for excitation current(%u)",
+							excitation_current);
+			ret = -EINVAL;
+			goto fail;
+		}
+	}
+
+	of_property_read_u32(child, "adi,rtd-curve", &rtd->rtd_curve);
+
+	of_node_put(phandle);
+	return &rtd->sensor;
+fail:
+	of_node_put(phandle);
+	return ERR_PTR(ret);
+}
+
+static struct ltc2983_sensor *ltc2983_thermistor_new(
+					const struct device_node *child,
+					struct ltc2983_data *st,
+					const struct ltc2983_sensor *sensor)
+{
+	struct ltc2983_thermistor *thermistor;
+	struct device *dev = &st->spi->dev;
+	struct device_node *phandle;
+	u32 excitation_current = 0;
+	int ret = 0;
+
+	thermistor = devm_kzalloc(dev, sizeof(*thermistor), GFP_KERNEL);
+	if (!thermistor)
+		return ERR_PTR(-ENOMEM);
+
+	phandle = of_parse_phandle(child, "adi,rsense-handle", 0);
+	if (!phandle) {
+		dev_err(dev, "Property adi,rsense-handle missing or invalid");
+		return ERR_PTR(-EINVAL);
+	}
+
+	ret = of_property_read_u32(phandle, "reg", &thermistor->r_sense_chan);
+	if (ret) {
+		dev_err(dev, "rsense channel must be configured...\n");
+		goto fail;
+	}
+
+	of_property_read_u32(child, "adi,sensor-config",
+			     &thermistor->sensor_config);
+	/* validate channel index */
+	if (!(thermistor->sensor_config & LTC2983_THERMISTOR_DIFF_MASK) &&
+	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
+		dev_err(&st->spi->dev,
+			"Invalid chann:%d for differential thermistor",
+								sensor->chan);
+		ret = -EINVAL;
+		goto fail;
+	}
+
+	/* check custom sensor */
+	if (sensor->type >= LTC2983_SENSOR_THERMISTOR_STEINHART) {
+		thermistor->custom = __ltc2983_custom_sensor_new(st, child,
+			sensor->type == LTC2983_SENSOR_THERMISTOR_STEINHART ?
+							  true : false, 64,
+							  false);
+		if (IS_ERR(thermistor->custom)) {
+			of_node_put(phandle);
+			return ERR_CAST(thermistor->custom);
+		}
+	}
+	/* set common parameters */
+	thermistor->sensor.fault_handler = ltc2983_common_fault_handler;
+	thermistor->sensor.assign_chan = ltc2983_thermistor_assign_chan;
+
+	ret = of_property_read_u32(child, "adi,excitation-current-nanoamp",
+				   &excitation_current);
+	if (ret) {
+		/* Auto range is not allowed for custom sensors */
+		if (sensor->type >= LTC2983_SENSOR_THERMISTOR_STEINHART)
+			/* default to 1uA */
+			thermistor->excitation_current = 0x03;
+		else
+			/* default to auto-range */
+			thermistor->excitation_current = 0x0c;
+	} else {
+		switch (excitation_current) {
+		case 0:
+			/* auto range */
+			if (sensor->type >=
+			    LTC2983_SENSOR_THERMISTOR_STEINHART) {
+				dev_err(&st->spi->dev,
+					"Auto Range not allowed for custom sensors\n");
+				ret = -EINVAL;
+				goto fail;
+			}
+			thermistor->excitation_current = 0x0c;
+			break;
+		case 250:
+			thermistor->excitation_current = 0x01;
+			break;
+		case 500:
+			thermistor->excitation_current = 0x02;
+			break;
+		case 1000:
+			thermistor->excitation_current = 0x03;
+			break;
+		case 5000:
+			thermistor->excitation_current = 0x04;
+			break;
+		case 10000:
+			thermistor->excitation_current = 0x05;
+			break;
+		case 25000:
+			thermistor->excitation_current = 0x06;
+			break;
+		case 50000:
+			thermistor->excitation_current = 0x07;
+			break;
+		case 100000:
+			thermistor->excitation_current = 0x08;
+			break;
+		case 250000:
+			thermistor->excitation_current = 0x09;
+			break;
+		case 500000:
+			thermistor->excitation_current = 0x0a;
+			break;
+		case 1000000:
+			thermistor->excitation_current = 0x0b;
+			break;
+		default:
+			dev_err(&st->spi->dev,
+				"Invalid value for excitation current(%u)",
+							excitation_current);
+			ret = -EINVAL;
+			goto fail;
+		}
+	}
+
+	of_node_put(phandle);
+	return &thermistor->sensor;
+fail:
+	of_node_put(phandle);
+	return ERR_PTR(ret);
+}
+
+static struct ltc2983_sensor *ltc2983_diode_new(
+					const struct device_node *child,
+					const struct ltc2983_data *st,
+					const struct ltc2983_sensor *sensor)
+{
+	struct ltc2983_diode *diode;
+	u32 temp = 0, excitation_current = 0;
+	int ret;
+
+	diode = devm_kzalloc(&st->spi->dev, sizeof(*diode), GFP_KERNEL);
+	if (!diode)
+		return ERR_PTR(-ENOMEM);
+
+	of_property_read_u32(child, "adi,sensor-config", &diode->sensor_config);
+	/* validate channel index */
+	if (!(diode->sensor_config & LTC2983_DIODE_DIFF_MASK) &&
+	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
+		dev_err(&st->spi->dev,
+			"Invalid chann:%d for differential thermistor",
+								sensor->chan);
+		return ERR_PTR(-EINVAL);
+	}
+	/* set common parameters */
+	diode->sensor.fault_handler = ltc2983_common_fault_handler;
+	diode->sensor.assign_chan = ltc2983_diode_assign_chan;
+
+	ret = of_property_read_u32(child, "adi,excitation-current-microamp",
+				   &excitation_current);
+	if (!ret) {
+		switch (excitation_current) {
+		case 10:
+			diode->excitation_current = 0x00;
+			break;
+		case 20:
+			diode->excitation_current = 0x01;
+			break;
+		case 40:
+			diode->excitation_current = 0x02;
+			break;
+		case 80:
+			diode->excitation_current = 0x03;
+			break;
+		default:
+			dev_err(&st->spi->dev,
+				"Invalid value for excitation current(%u)",
+							excitation_current);
+			return ERR_PTR(-EINVAL);
+		}
+	}
+
+	of_property_read_u32(child, "adi,ideal-factor-value", &temp);
+
+	/* 2^20 resolution */
+	diode->ideal_factor_value = __convert_to_raw(temp, 1048576);
+
+	return &diode->sensor;
+}
+
+static struct ltc2983_sensor *ltc2983_r_sense_new(struct device_node *child,
+					struct ltc2983_data *st,
+					const struct ltc2983_sensor *sensor)
+{
+	struct ltc2983_rsense *rsense;
+	int ret;
+	u64 temp;
+
+	rsense = devm_kzalloc(&st->spi->dev, sizeof(*rsense), GFP_KERNEL);
+	if (!rsense)
+		return ERR_PTR(-ENOMEM);
+
+	/* validate channel index */
+	if (sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
+		dev_err(&st->spi->dev, "Invalid chann:%d for r_sense",
+							sensor->chan);
+		return ERR_PTR(-EINVAL);
+	}
+	/* get raw value */
+	ret = of_property_read_u64(child, "adi,rsense-val-micro-ohms", &temp);
+	if (ret) {
+		dev_err(&st->spi->dev, "Property adi,rsense-val-micro-ohms missing\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	/* 2^10 resolution */
+	rsense->r_sense_val = __convert_to_raw(temp, 1024);
+
+	/* set common parameters */
+	rsense->sensor.assign_chan = ltc2983_r_sense_assign_chan;
+
+	return &rsense->sensor;
+}
+
+static struct ltc2983_sensor *ltc2983_adc_new(struct device_node *child,
+					 struct ltc2983_data *st,
+					 const struct ltc2983_sensor *sensor)
+{
+	struct ltc2983_adc *adc;
+
+	adc = devm_kzalloc(&st->spi->dev, sizeof(*adc), GFP_KERNEL);
+	if (!adc)
+		return ERR_PTR(-ENOMEM);
+
+	if (of_property_read_bool(child, "adi,single-ended"))
+		adc->single_ended = true;
+
+	if (!adc->single_ended &&
+	    sensor->chan < LTC2983_DIFFERENTIAL_CHAN_MIN) {
+		dev_err(&st->spi->dev, "Invalid chan:%d for differential adc\n",
+								sensor->chan);
+		return ERR_PTR(-EINVAL);
+	}
+	/* set common parameters */
+	adc->sensor.assign_chan = ltc2983_adc_assign_chan;
+	adc->sensor.fault_handler = ltc2983_common_fault_handler;
+
+	return &adc->sensor;
+}
+
+static int ltc2983_chan_read(struct ltc2983_data *st,
+			const struct ltc2983_sensor *sensor, int *val)
+{
+	u32 start_conversion = 0;
+	int ret;
+	unsigned long time;
+	__be32 temp;
+
+	/*
+	 * Do not allow channel readings if device is in sleep state.
+	 * A read/write on the spi bus would bring the device prematurely
+	 * out of sleep.
+	 */
+	if (st->sleep)
+		return -EPERM;
+
+	start_conversion = LTC2983_STATUS_START(true);
+	start_conversion |= LTC2983_STATUS_CHAN_SEL(sensor->chan);
+	dev_dbg(&st->spi->dev, "Start conversion on chan:%d, status:%02X\n",
+		sensor->chan, start_conversion);
+	/* start conversion */
+	ret = regmap_write(st->regmap, LTC2983_STATUS_REG, start_conversion);
+	if (ret)
+		return ret;
+
+	reinit_completion(&st->completion);
+	/*
+	 * wait for conversion to complete.
+	 * 300 ms should be more than enough to complete the conversion.
+	 * Depending on the sensor configuration, there are 2/3 conversions
+	 * cycles of 82ms.
+	 */
+	time = wait_for_completion_timeout(&st->completion,
+					   msecs_to_jiffies(300));
+	if (!time) {
+		dev_warn(&st->spi->dev, "Conversion timed out\n");
+		return -ETIMEDOUT;
+	}
+
+	/* read the converted data */
+	ret = regmap_bulk_read(st->regmap, LTC2983_CHAN_RES_ADDR(sensor->chan),
+			       &temp, sizeof(temp));
+	if (ret)
+		return ret;
+
+	*val = __be32_to_cpu(temp);
+
+	if (!(LTC2983_RES_VALID_MASK & *val)) {
+		dev_err(&st->spi->dev, "Invalid conversion detected\n");
+		return -EIO;
+	}
+
+	ret = sensor->fault_handler(st, *val);
+	if (ret)
+		return ret;
+
+	*val = sign_extend32((*val) & LTC2983_DATA_MASK, LTC2983_DATA_SIGN_BIT);
+	return 0;
+}
+
+static int ltc2983_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct ltc2983_data *st = iio_priv(indio_dev);
+	int ret;
+
+	/* sanity check */
+	if (chan->address >= st->num_channels) {
+		dev_err(&st->spi->dev, "Invalid chan address:%ld",
+							chan->address);
+		return -EINVAL;
+	}
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&st->lock);
+		ret = ltc2983_chan_read(st, st->sensors[chan->address], val);
+		mutex_unlock(&st->lock);
+		return ret ?: IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->type) {
+		case IIO_TEMP:
+			/* value in milli degrees */
+			*val = 1000;
+			/* 2^10 */
+			*val2 = 1024;
+			return IIO_VAL_FRACTIONAL;
+		case IIO_VOLTAGE:
+			/* value in millivolt */
+			*val = 1000;
+			/* 2^21 */
+			*val2 = 2097152;
+			return IIO_VAL_FRACTIONAL;
+		default:
+			return -EINVAL;
+		}
+	}
+
+	return -EINVAL;
+}
+
+static int ltc2983_reg_access(struct iio_dev *indio_dev,
+			      unsigned int reg,
+			      unsigned int writeval,
+			      unsigned int *readval)
+{
+	struct ltc2983_data *st = iio_priv(indio_dev);
+
+	/* check comment in ltc2983_chan_read() */
+	if (st->sleep)
+		return -EPERM;
+
+	if (readval)
+		return regmap_read(st->regmap, reg, readval);
+	else
+		return regmap_write(st->regmap, reg, writeval);
+}
+
+static irqreturn_t ltc2983_irq_handler(int irq, void *data)
+{
+	struct ltc2983_data *st = data;
+
+	complete(&st->completion);
+	return IRQ_HANDLED;
+}
+
+#define LTC2983_CHAN(__type, index, __address) ({ \
+	struct iio_chan_spec __chan = { \
+		.type = __type, \
+		.indexed = 1, \
+		.channel = index, \
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+		.address = __address, \
+	}; \
+	__chan; \
+})
+
+static int ltc2983_parse_dt(struct ltc2983_data *st)
+{
+	struct device_node *child;
+	struct device *dev = &st->spi->dev;
+	int ret = 0, chan = 0, channel_avail_mask = 0;
+
+	if (!of_property_read_bool(dev->of_node, "adi,temperature-celcius"))
+		st->temp_farenheit = true;
+
+	of_property_read_u32(dev->of_node, "adi,mux-delay-config-us",
+			     &st->mux_delay_config);
+
+	of_property_read_u32(dev->of_node, "adi,filter-notch-freq",
+			     &st->filter_notch_freq);
+
+	st->num_channels = of_get_available_child_count(dev->of_node);
+	st->sensors = devm_kcalloc(dev, st->num_channels, sizeof(*st->sensors),
+				   GFP_KERNEL);
+	if (!st->sensors)
+		return -ENOMEM;
+
+	st->iio_channels = st->num_channels;
+	for_each_available_child_of_node(dev->of_node, child) {
+		struct ltc2983_sensor sensor;
+
+		ret = of_property_read_u32(child, "reg", &sensor.chan);
+		if (ret) {
+			dev_err(dev, "reg property must given for child nodes\n");
+			return ret;
+		}
+
+		/* check if we have a valid channel */
+		if (sensor.chan < LTC2983_MIN_CHANNELS_NR ||
+		    sensor.chan > LTC2983_MAX_CHANNELS_NR) {
+			dev_err(dev,
+				"chan:%d must be from 1 to 20\n", sensor.chan);
+			return -EINVAL;
+		} else if (channel_avail_mask & BIT(sensor.chan)) {
+			dev_err(dev, "chan:%d already in use\n", sensor.chan);
+			return -EINVAL;
+		}
+
+		ret = of_property_read_u32(child, "adi,sensor-type",
+					       &sensor.type);
+		if (ret) {
+			dev_err(dev,
+				"adi,sensor-type property must given for child nodes\n");
+			return ret;
+		}
+
+		dev_dbg(dev, "Create new sensor, type %u, chann %u",
+								sensor.type,
+								sensor.chan);
+
+		if (sensor.type >= LTC2983_SENSOR_THERMOCOUPLE &&
+		    sensor.type <= LTC2983_SENSOR_THERMOCOUPLE_CUSTOM) {
+			st->sensors[chan] = ltc2983_thermocouple_new(child, st,
+								     &sensor);
+		} else if (sensor.type >= LTC2983_SENSOR_RTD &&
+			   sensor.type <= LTC2983_SENSOR_RTD_CUSTOM) {
+			st->sensors[chan] = ltc2983_rtd_new(child, st, &sensor);
+		} else if (sensor.type >= LTC2983_SENSOR_THERMISTOR &&
+			   sensor.type <= LTC2983_SENSOR_THERMISTOR_CUSTOM) {
+			st->sensors[chan] = ltc2983_thermistor_new(child, st,
+								   &sensor);
+		} else if (sensor.type == LTC2983_SENSOR_DIODE) {
+			st->sensors[chan] = ltc2983_diode_new(child, st,
+							      &sensor);
+		} else if (sensor.type == LTC2983_SENSOR_SENSE_RESISTOR) {
+			st->sensors[chan] = ltc2983_r_sense_new(child, st,
+								&sensor);
+			/* don't add rsense to iio */
+			st->iio_channels--;
+		} else if (sensor.type == LTC2983_SENSOR_DIRECT_ADC) {
+			st->sensors[chan] = ltc2983_adc_new(child, st, &sensor);
+		} else {
+			dev_err(dev, "Unknown sensor type %d\n", sensor.type);
+			return -EINVAL;
+		}
+
+		if (IS_ERR(st->sensors[chan])) {
+			dev_err(dev, "Failed to create sensor %ld",
+						PTR_ERR(st->sensors[chan]));
+			return PTR_ERR(st->sensors[chan]);
+		}
+		/* set generic sensor parameters */
+		st->sensors[chan]->chan = sensor.chan;
+		st->sensors[chan]->type = sensor.type;
+
+		channel_avail_mask |= BIT(sensor.chan);
+		chan++;
+	}
+
+	return 0;
+}
+
+static int ltc2983_setup(struct ltc2983_data *st, bool assign_iio)
+{
+	u32 iio_chan_t = 0, iio_chan_v = 0, chan, iio_idx = 0;
+	u32 global_cfg = 0;
+	int ret;
+	unsigned long time;
+
+	/* make sure the device is up */
+	time = wait_for_completion_timeout(&st->completion,
+					    msecs_to_jiffies(250));
+
+	if (!time) {
+		dev_err(&st->spi->dev, "Device startup timed out\n");
+		return -ETIMEDOUT;
+	}
+
+	st->iio_chan = devm_kzalloc(&st->spi->dev,
+				    st->iio_channels * sizeof(*st->iio_chan),
+				    GFP_KERNEL);
+
+	if (!st->iio_chan)
+		return -ENOMEM;
+
+	global_cfg = LTC2983_NOTCH_FREQ(st->filter_notch_freq);
+	global_cfg |= LTC2983_TEMP_UNITS(st->temp_farenheit);
+	regmap_write(st->regmap, LTC2983_GLOBAL_CONFIG_REG, global_cfg);
+	regmap_write(st->regmap, LTC2983_MUX_CONFIG_REG, st->mux_delay_config);
+
+	for (chan = 0; chan < st->num_channels; chan++) {
+		u32 chan_type = 0, *iio_chan;
+
+		ret = st->sensors[chan]->assign_chan(st, st->sensors[chan]);
+		if (ret)
+			return ret;
+		/*
+		 * The assign_iio flag is necessary for when the device is
+		 * coming out of sleep. In that case, we just need to
+		 * re-configure the device channels.
+		 * We also don't assign iio channels for rsense.
+		 */
+		if (st->sensors[chan]->type == LTC2983_SENSOR_SENSE_RESISTOR ||
+		    !assign_iio)
+			continue;
+
+		/* assign iio channel */
+		if (st->sensors[chan]->type != LTC2983_SENSOR_DIRECT_ADC) {
+			chan_type = IIO_TEMP;
+			iio_chan = &iio_chan_t;
+		} else {
+			chan_type = IIO_VOLTAGE;
+			iio_chan = &iio_chan_v;
+		}
+
+		/*
+		 * add chan as the iio .address so that, we can directly
+		 * reference the sensor given the iio_chan_spec
+		 */
+		st->iio_chan[iio_idx++] = LTC2983_CHAN(chan_type, (*iio_chan)++,
+						       chan);
+	}
+
+	return 0;
+}
+
+static const struct regmap_range ltc2983_reg_ranges[] = {
+	regmap_reg_range(LTC2983_STATUS_REG, LTC2983_STATUS_REG),
+	regmap_reg_range(LTC2983_TEMP_RES_START_REG, LTC2983_TEMP_RES_END_REG),
+	regmap_reg_range(LTC2983_GLOBAL_CONFIG_REG, LTC2983_GLOBAL_CONFIG_REG),
+	regmap_reg_range(LTC2983_MULT_CHANNEL_START_REG,
+			 LTC2983_MULT_CHANNEL_END_REG),
+	regmap_reg_range(LTC2983_MUX_CONFIG_REG, LTC2983_MUX_CONFIG_REG),
+	regmap_reg_range(LTC2983_CHAN_ASSIGN_START_REG,
+			 LTC2983_CHAN_ASSIGN_END_REG),
+	regmap_reg_range(LTC2983_CUST_SENS_TBL_START_REG,
+			 LTC2983_CUST_SENS_TBL_END_REG),
+};
+
+static const struct regmap_access_table ltc2983_reg_table = {
+	.yes_ranges = ltc2983_reg_ranges,
+	.n_yes_ranges = ARRAY_SIZE(ltc2983_reg_ranges),
+};
+
+/*
+ *  The reg_bits are actually 12 but the device needs the first *complete*
+ *  byte for the command (R/W).
+ */
+static const struct regmap_config ltc2983_regmap_config = {
+	.reg_bits = 24,
+	.val_bits = 8,
+	.wr_table = &ltc2983_reg_table,
+	.rd_table = &ltc2983_reg_table,
+	.read_flag_mask = GENMASK(1, 0),
+	.write_flag_mask = BIT(1),
+};
+
+static const struct  iio_info ltc2983_iio_info = {
+	.read_raw = ltc2983_read_raw,
+	.debugfs_reg_access = ltc2983_reg_access,
+};
+
+static int ltc2983_probe(struct spi_device *spi)
+{
+	struct ltc2983_data *st;
+	struct iio_dev *indio_dev;
+	const char *name = spi_get_device_id(spi)->name;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+
+	st->regmap = devm_regmap_init_spi(spi, &ltc2983_regmap_config);
+	if (IS_ERR(st->regmap)) {
+		dev_err(&spi->dev, "Failed to initialize regmap\n");
+		return PTR_ERR(st->regmap);
+	}
+
+	mutex_init(&st->lock);
+	init_completion(&st->completion);
+	st->spi = spi;
+	spi_set_drvdata(spi, st);
+
+	ret = ltc2983_parse_dt(st);
+	if (ret)
+		return ret;
+	/*
+	 * let's request the irq now so it is used to sync the device
+	 * startup in ltc2983_setup()
+	 */
+	ret = devm_request_threaded_irq(&spi->dev, spi->irq, NULL,
+					ltc2983_irq_handler, IRQF_ONESHOT |
+					IRQF_TRIGGER_RISING, name, st);
+	if (ret) {
+		dev_err(&spi->dev, "failed to request an irq, %d", ret);
+		return ret;
+	}
+
+	ret = ltc2983_setup(st, true);
+	if (ret)
+		return ret;
+
+	indio_dev->dev.parent = &spi->dev;
+	indio_dev->name = name;
+	indio_dev->num_channels = st->iio_channels;
+	indio_dev->channels = st->iio_chan;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &ltc2983_iio_info;
+
+	return devm_iio_device_register(&spi->dev, indio_dev);
+}
+
+static int __maybe_unused ltc2983_resume(struct device *dev)
+{
+	struct ltc2983_data *st = spi_get_drvdata(to_spi_device(dev));
+	int ret;
+
+	mutex_lock(&st->lock);
+	/* dummy read to bring the device out of sleep */
+	regmap_read(st->regmap, LTC2983_STATUS_REG, &ret);
+	/* we need to re-assign the channels */
+	ret = ltc2983_setup(st, false);
+	st->sleep = false;
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+static int __maybe_unused ltc2983_suspend(struct device *dev)
+{
+	struct ltc2983_data *st = spi_get_drvdata(to_spi_device(dev));
+	int ret;
+
+	mutex_lock(&st->lock);
+	ret = regmap_write(st->regmap, LTC2983_STATUS_REG, LTC2983_SLEEP);
+	st->sleep = true;
+	mutex_unlock(&st->lock);
+
+	return ret;
+}
+
+static SIMPLE_DEV_PM_OPS(ltc2983_pm_ops, ltc2983_suspend, ltc2983_resume);
+
+static const struct spi_device_id ltc2983_id_table[] = {
+	{ "ltc2983" },
+	{},
+};
+MODULE_DEVICE_TABLE(spi, ltc2983_id_table);
+
+static const struct of_device_id ltc2983_of_match[] = {
+	{ .compatible = "adi,ltc2983" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, ltc2983_id_table);
+
+static struct spi_driver ltc2983_driver = {
+	.driver = {
+		.name = "ltc2983",
+		.of_match_table = ltc2983_of_match,
+		.pm = &ltc2983_pm_ops,
+	},
+	.probe = ltc2983_probe,
+	.id_table = ltc2983_id_table,
+};
+
+module_spi_driver(ltc2983_driver);
+
+MODULE_AUTHOR("Nuno Sa <[e-mail]>");
+MODULE_DESCRIPTION("Analog Devices LTC2983 SPI Temperature sensors");
+MODULE_LICENSE("GPL");