[v3,2/4] hwmon: Add support for SPD5118 compliant temperature sensors

Commit Message

Guenter Roeck May 31, 2024, 11:05 p.m. UTC

Add support for SPD5118 (Jedec JESD300) compliant temperature
sensors. Such sensors are typically found on DDR5 memory modules.

Cc: René Rebe <[e-mail]>
Cc: Thomas Weißschuh <[e-mail]>
Reviewed-by: Thomas Weißschuh <[e-mail]>
Tested-by: Thomas Weißschuh <[e-mail]>
Signed-off-by: Guenter Roeck <[e-mail]>
---
v3: Shorten JESD300-5B.01 to JESD300; 5B.01 refers to the version
    of the standard
    Drop unnecessary 'attr' parameter from spd5118_{read,write}_enable()

v2: Drop PEC property documentation
    Add note indicating that alarm attributes are sticky until read
    to documentation
    Fix detect function
    Fix misspelling in Makefile (CONFIG_SENSORS_SPD5118->CONFIG_SENSORS_SPD5118)

 Documentation/hwmon/index.rst   |   1 +
 Documentation/hwmon/spd5118.rst |  55 ++++
 drivers/hwmon/Kconfig           |  12 +
 drivers/hwmon/Makefile          |   1 +
 drivers/hwmon/spd5118.c         | 481 ++++++++++++++++++++++++++++++++
 5 files changed, 550 insertions(+)
 create mode 100644 Documentation/hwmon/spd5118.rst
 create mode 100644 drivers/hwmon/spd5118.c

Comments

Wolfram Sang June 1, 2024, 1:28 a.m. UTC | #1

> +/* Return 0 if detection is successful, -ENODEV otherwise */
> +static int spd5118_detect(struct i2c_client *client, struct i2c_board_info *info)
> +{
> +	struct i2c_adapter *adapter = client->adapter;
> +	int regval;
> +
> +	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
> +				     I2C_FUNC_SMBUS_WORD_DATA))
> +		return -ENODEV;
> +
> +	regval = i2c_smbus_read_word_swapped(client, SPD5118_REG_TYPE);
> +	if (regval != 0x5118)
> +		return -ENODEV;
> +
> +	regval = i2c_smbus_read_word_data(client, SPD5118_REG_VENDOR);
> +	if (regval < 0 || !spd5118_vendor_valid(regval & 0xff, regval >> 8))
> +		return -ENODEV;
> +
> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_CAPABILITY);
> +	if (regval < 0)
> +		return -ENODEV;
> +	if (!(regval & SPD5118_CAP_TS_SUPPORT) || (regval & 0xfc))
> +		return -ENODEV;
> +
> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_TEMP_CLR);
> +	if (regval)
> +		return -ENODEV;
> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_ERROR_CLR);
> +	if (regval)
> +		return -ENODEV;
> +
> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_REVISION);
> +	if (regval < 0 || (regval & 0xc1))
> +		return -ENODEV;
> +
> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_TEMP_CONFIG);
> +	if (regval < 0)
> +		return -ENODEV;
> +	if (regval & ~SPD5118_TS_DISABLE)
> +		return -ENODEV;
> +
> +	strscpy(info->type, "spd5118", I2C_NAME_SIZE);
> +	return 0;
> +}

What about adding DDR5 to i2c_register_spd() and dropping this function?

Guenter Roeck June 1, 2024, 3:40 a.m. UTC | #2

On 5/31/24 18:28, Wolfram Sang wrote:
> 
>> +/* Return 0 if detection is successful, -ENODEV otherwise */
>> +static int spd5118_detect(struct i2c_client *client, struct i2c_board_info *info)
>> +{
>> +	struct i2c_adapter *adapter = client->adapter;
>> +	int regval;
>> +
>> +	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
>> +				     I2C_FUNC_SMBUS_WORD_DATA))
>> +		return -ENODEV;
>> +
>> +	regval = i2c_smbus_read_word_swapped(client, SPD5118_REG_TYPE);
>> +	if (regval != 0x5118)
>> +		return -ENODEV;
>> +
>> +	regval = i2c_smbus_read_word_data(client, SPD5118_REG_VENDOR);
>> +	if (regval < 0 || !spd5118_vendor_valid(regval & 0xff, regval >> 8))
>> +		return -ENODEV;
>> +
>> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_CAPABILITY);
>> +	if (regval < 0)
>> +		return -ENODEV;
>> +	if (!(regval & SPD5118_CAP_TS_SUPPORT) || (regval & 0xfc))
>> +		return -ENODEV;
>> +
>> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_TEMP_CLR);
>> +	if (regval)
>> +		return -ENODEV;
>> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_ERROR_CLR);
>> +	if (regval)
>> +		return -ENODEV;
>> +
>> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_REVISION);
>> +	if (regval < 0 || (regval & 0xc1))
>> +		return -ENODEV;
>> +
>> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_TEMP_CONFIG);
>> +	if (regval < 0)
>> +		return -ENODEV;
>> +	if (regval & ~SPD5118_TS_DISABLE)
>> +		return -ENODEV;
>> +
>> +	strscpy(info->type, "spd5118", I2C_NAME_SIZE);
>> +	return 0;
>> +}
> 
> What about adding DDR5 to i2c_register_spd() and dropping this function?
> 

Yes, that should be the next step. I didn't want to do that here because it
would introduce a cross-subsystem dependency. Of course, that depends a bit
on your position about such dependencies. If I do that as part of this series,
would you Ack it, or would you want to handle that through the i2c tree ?

Guenter

Armin Wolf June 1, 2024, 7:14 p.m. UTC | #3

Am 01.06.24 um 01:05 schrieb Guenter Roeck:

> Add support for SPD5118 (Jedec JESD300) compliant temperature
> sensors. Such sensors are typically found on DDR5 memory modules.

Tested-by: Armin Wolf <[e-mail]>
Reviewed-by: Armin Wolf <[e-mail]>

> Cc: René Rebe <[e-mail]>
> Cc: Thomas Weißschuh <[e-mail]>
> Reviewed-by: Thomas Weißschuh <[e-mail]>
> Tested-by: Thomas Weißschuh <[e-mail]>
> Signed-off-by: Guenter Roeck <[e-mail]>
> ---
> v3: Shorten JESD300-5B.01 to JESD300; 5B.01 refers to the version
>      of the standard
>      Drop unnecessary 'attr' parameter from spd5118_{read,write}_enable()
>
> v2: Drop PEC property documentation
>      Add note indicating that alarm attributes are sticky until read
>      to documentation
>      Fix detect function
>      Fix misspelling in Makefile (CONFIG_SENSORS_SPD5118->CONFIG_SENSORS_SPD5118)
>
>   Documentation/hwmon/index.rst   |   1 +
>   Documentation/hwmon/spd5118.rst |  55 ++++
>   drivers/hwmon/Kconfig           |  12 +
>   drivers/hwmon/Makefile          |   1 +
>   drivers/hwmon/spd5118.c         | 481 ++++++++++++++++++++++++++++++++
>   5 files changed, 550 insertions(+)
>   create mode 100644 Documentation/hwmon/spd5118.rst
>   create mode 100644 drivers/hwmon/spd5118.c
>
> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> index 03d313af469a..6e7b8726b60c 100644
> --- a/Documentation/hwmon/index.rst
> +++ b/Documentation/hwmon/index.rst
> @@ -215,6 +215,7 @@ Hardware Monitoring Kernel Drivers
>      smsc47m192
>      smsc47m1
>      sparx5-temp
> +   spd5118
>      stpddc60
>      surface_fan
>      sy7636a-hwmon
> diff --git a/Documentation/hwmon/spd5118.rst b/Documentation/hwmon/spd5118.rst
> new file mode 100644
> index 000000000000..a15d75aa2066
> --- /dev/null
> +++ b/Documentation/hwmon/spd5118.rst
> @@ -0,0 +1,55 @@
> +.. SPDX-License-Identifier: GPL-2.0-or-later
> +
> +Kernel driver spd5118
> +=====================
> +
> +Supported chips:
> +
> +  * SPD5118 (JEDEC JESD300) compliant temperature sensor chips
> +
> +    JEDEC standard download:
> +	https://www.jedec.org/standards-documents/docs/jesd300-5b01
> +	(account required)
> +
> +
> +    Prefix: 'spd5118'
> +
> +    Addresses scanned: I2C 0x50 - 0x57
> +
> +Author:
> +	Guenter Roeck <[e-mail]>
> +
> +
> +Description
> +-----------
> +
> +This driver implements support for SPD5118 (JEDEC JESD300) compliant temperature
> +sensors, which are used on many DDR5 memory modules. Some systems use the sensor
> +to prevent memory overheating by automatically throttling the memory controller.
> +
> +The driver auto-detects SPD5118 compliant chips, but can also be instantiated
> +using devicetree/firmware nodes.
> +
> +A SPD5118 compliant chip supports a single temperature sensor. Critical minimum,
> +minimum, maximum, and critical temperature can be configured. There are alarms
> +for low critical, low, high, and critical thresholds.
> +
> +
> +Hardware monitoring sysfs entries
> +---------------------------------
> +
> +======================= ==================================
> +temp1_input		Temperature (RO)
> +temp1_lcrit		Low critical high temperature (RW)
> +temp1_min		Minimum temperature (RW)
> +temp1_max		Maximum temperature (RW)
> +temp1_crit		Critical high temperature (RW)
> +
> +temp1_lcrit_alarm	Temperature low critical alarm
> +temp1_min_alarm		Temperature low alarm
> +temp1_max_alarm		Temperature high alarm
> +temp1_crit_alarm	Temperature critical alarm
> +======================= ==================================
> +
> +Alarm attributes are sticky until read and will be cleared afterwards
> +unless the alarm condition still applies.
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index e14ae18a973b..d0fb5fe1b2ac 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -2181,6 +2181,18 @@ config SENSORS_INA3221
>   	  This driver can also be built as a module. If so, the module
>   	  will be called ina3221.
>
> +config SENSORS_SPD5118
> +	tristate "SPD5118 Compliant Temperature Sensors"
> +	depends on I2C
> +	select REGMAP_I2C
> +	help
> +	  If you say yes here you get support for SPD5118 (JEDEC JESD300)
> +	  compliant temperature sensors. Such sensors are found on DDR5 memory
> +	  modules.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called spd5118.
> +
>   config SENSORS_TC74
>   	tristate "Microchip TC74"
>   	depends on I2C
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index e3f25475d1f0..6574ca67d761 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -207,6 +207,7 @@ obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o
>   obj-$(CONFIG_SENSORS_SMSC47M1)	+= smsc47m1.o
>   obj-$(CONFIG_SENSORS_SMSC47M192)+= smsc47m192.o
>   obj-$(CONFIG_SENSORS_SPARX5)	+= sparx5-temp.o
> +obj-$(CONFIG_SENSORS_SPD5118)	+= spd5118.o
>   obj-$(CONFIG_SENSORS_STTS751)	+= stts751.o
>   obj-$(CONFIG_SENSORS_SURFACE_FAN)+= surface_fan.o
>   obj-$(CONFIG_SENSORS_SY7636A)	+= sy7636a-hwmon.o
> diff --git a/drivers/hwmon/spd5118.c b/drivers/hwmon/spd5118.c
> new file mode 100644
> index 000000000000..d3fc0ae17743
> --- /dev/null
> +++ b/drivers/hwmon/spd5118.c
> @@ -0,0 +1,481 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Driver for Jedec 5118 compliant temperature sensors
> + *
> + * Derived from https://github.com/Steve-Tech/SPD5118-DKMS
> + * Originally from T/2 driver at https://t2sde.org/packages/linux
> + *	Copyright (c) 2023 René Rebe, ExactCODE GmbH; Germany.
> + *
> + * Copyright (c) 2024 Guenter Roeck
> + *
> + * Inspired by ee1004.c and jc42.c.
> + *
> + * SPD5118 compliant temperature sensors are typically used on DDR5
> + * memory modules.
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/bits.h>
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/hwmon.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/units.h>
> +
> +/* Addresses to scan */
> +static const unsigned short normal_i2c[] = {
> +	0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, I2C_CLIENT_END };
> +
> +/* SPD5118 registers. */
> +#define SPD5118_REG_TYPE		0x00	/* MR0:MR1 */
> +#define SPD5118_REG_REVISION		0x02	/* MR2 */
> +#define SPD5118_REG_VENDOR		0x03	/* MR3:MR4 */
> +#define SPD5118_REG_CAPABILITY		0x05	/* MR5 */
> +#define SPD5118_REG_I2C_LEGACY_MODE	0x0B	/* MR11 */
> +#define SPD5118_REG_TEMP_CLR		0x13	/* MR19 */
> +#define SPD5118_REG_ERROR_CLR		0x14	/* MR20 */
> +#define SPD5118_REG_TEMP_CONFIG		0x1A	/* MR26 */
> +#define SPD5118_REG_TEMP_MAX		0x1c	/* MR28:MR29 */
> +#define SPD5118_REG_TEMP_MIN		0x1e	/* MR30:MR31 */
> +#define SPD5118_REG_TEMP_CRIT		0x20	/* MR32:MR33 */
> +#define SPD5118_REG_TEMP_LCRIT		0x22	/* MR34:MR35 */
> +#define SPD5118_REG_TEMP		0x31	/* MR49:MR50 */
> +#define SPD5118_REG_TEMP_STATUS		0x33	/* MR51 */
> +
> +#define SPD5118_TEMP_STATUS_HIGH	BIT(0)
> +#define SPD5118_TEMP_STATUS_LOW		BIT(1)
> +#define SPD5118_TEMP_STATUS_CRIT	BIT(2)
> +#define SPD5118_TEMP_STATUS_LCRIT	BIT(3)
> +
> +#define SPD5118_CAP_TS_SUPPORT		BIT(1)	/* temperature sensor support */
> +
> +#define SPD5118_TS_DISABLE		BIT(0)	/* temperature sensor disable */
> +
> +/* Temperature unit in millicelsius */
> +#define SPD5118_TEMP_UNIT		(MILLIDEGREE_PER_DEGREE / 4)
> +/* Representable temperature range in millicelsius */
> +#define SPD5118_TEMP_RANGE_MIN		-256000
> +#define SPD5118_TEMP_RANGE_MAX		255750
> +
> +static int spd5118_temp_from_reg(u16 reg)
> +{
> +	int temp = sign_extend32(reg >> 2, 10);
> +
> +	return temp * SPD5118_TEMP_UNIT;
> +}
> +
> +static u16 spd5118_temp_to_reg(long temp)
> +{
> +	temp = clamp_val(temp, SPD5118_TEMP_RANGE_MIN, SPD5118_TEMP_RANGE_MAX);
> +	return (DIV_ROUND_CLOSEST(temp, SPD5118_TEMP_UNIT) & 0x7ff) << 2;
> +}
> +
> +static int spd5118_read_temp(struct regmap *regmap, u32 attr, long *val)
> +{
> +	int reg, err;
> +	u8 regval[2];
> +	u16 temp;
> +
> +	switch (attr) {
> +	case hwmon_temp_input:
> +		reg = SPD5118_REG_TEMP;
> +		break;
> +	case hwmon_temp_max:
> +		reg = SPD5118_REG_TEMP_MAX;
> +		break;
> +	case hwmon_temp_min:
> +		reg = SPD5118_REG_TEMP_MIN;
> +		break;
> +	case hwmon_temp_crit:
> +		reg = SPD5118_REG_TEMP_CRIT;
> +		break;
> +	case hwmon_temp_lcrit:
> +		reg = SPD5118_REG_TEMP_LCRIT;
> +		break;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	err = regmap_bulk_read(regmap, reg, regval, 2);
> +	if (err)
> +		return err;
> +
> +	temp = (regval[1] << 8) | regval[0];
> +
> +	*val = spd5118_temp_from_reg(temp);
> +	return 0;
> +}
> +
> +static int spd5118_read_alarm(struct regmap *regmap, u32 attr, long *val)
> +{
> +	unsigned int mask, regval;
> +	int err;
> +
> +	switch (attr) {
> +	case hwmon_temp_max_alarm:
> +		mask = SPD5118_TEMP_STATUS_HIGH;
> +		break;
> +	case hwmon_temp_min_alarm:
> +		mask = SPD5118_TEMP_STATUS_LOW;
> +		break;
> +	case hwmon_temp_crit_alarm:
> +		mask = SPD5118_TEMP_STATUS_CRIT;
> +		break;
> +	case hwmon_temp_lcrit_alarm:
> +		mask = SPD5118_TEMP_STATUS_LCRIT;
> +		break;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	err = regmap_read(regmap, SPD5118_REG_TEMP_STATUS, &regval);
> +	if (err < 0)
> +		return err;
> +	*val = !!(regval & mask);
> +	if (*val)
> +		return regmap_write(regmap, SPD5118_REG_TEMP_CLR, mask);
> +	return 0;
> +}
> +
> +static int spd5118_read_enable(struct regmap *regmap, long *val)
> +{
> +	u32 regval;
> +	int err;
> +
> +	err = regmap_read(regmap, SPD5118_REG_TEMP_CONFIG, &regval);
> +	if (err < 0)
> +		return err;
> +	*val = !(regval & SPD5118_TS_DISABLE);
> +	return 0;
> +}
> +
> +static int spd5118_read(struct device *dev, enum hwmon_sensor_types type,
> +			u32 attr, int channel, long *val)
> +{
> +	struct regmap *regmap = dev_get_drvdata(dev);
> +
> +	if (type != hwmon_temp)
> +		return -EOPNOTSUPP;
> +
> +	switch (attr) {
> +	case hwmon_temp_input:
> +	case hwmon_temp_max:
> +	case hwmon_temp_min:
> +	case hwmon_temp_crit:
> +	case hwmon_temp_lcrit:
> +		return spd5118_read_temp(regmap, attr, val);
> +	case hwmon_temp_max_alarm:
> +	case hwmon_temp_min_alarm:
> +	case hwmon_temp_crit_alarm:
> +	case hwmon_temp_lcrit_alarm:
> +		return spd5118_read_alarm(regmap, attr, val);
> +	case hwmon_temp_enable:
> +		return spd5118_read_enable(regmap, val);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int spd5118_write_temp(struct regmap *regmap, u32 attr, long val)
> +{
> +	u8 regval[2];
> +	u16 temp;
> +	int reg;
> +
> +	switch (attr) {
> +	case hwmon_temp_max:
> +		reg = SPD5118_REG_TEMP_MAX;
> +		break;
> +	case hwmon_temp_min:
> +		reg = SPD5118_REG_TEMP_MIN;
> +		break;
> +	case hwmon_temp_crit:
> +		reg = SPD5118_REG_TEMP_CRIT;
> +		break;
> +	case hwmon_temp_lcrit:
> +		reg = SPD5118_REG_TEMP_LCRIT;
> +		break;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	temp = spd5118_temp_to_reg(val);
> +	regval[0] = temp & 0xff;
> +	regval[1] = temp >> 8;
> +
> +	return regmap_bulk_write(regmap, reg, regval, 2);
> +}
> +
> +static int spd5118_write_enable(struct regmap *regmap, long val)
> +{
> +	if (val && val != 1)
> +		return -EINVAL;
> +
> +	return regmap_update_bits(regmap, SPD5118_REG_TEMP_CONFIG,
> +				  SPD5118_TS_DISABLE,
> +				  val ? 0 : SPD5118_TS_DISABLE);
> +}
> +
> +static int spd5118_temp_write(struct regmap *regmap, u32 attr, long val)
> +{
> +	switch (attr) {
> +	case hwmon_temp_max:
> +	case hwmon_temp_min:
> +	case hwmon_temp_crit:
> +	case hwmon_temp_lcrit:
> +		return spd5118_write_temp(regmap, attr, val);
> +	case hwmon_temp_enable:
> +		return spd5118_write_enable(regmap, val);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int spd5118_write(struct device *dev, enum hwmon_sensor_types type,
> +			 u32 attr, int channel, long val)
> +{
> +	struct regmap *regmap = dev_get_drvdata(dev);
> +
> +	switch (type) {
> +	case hwmon_temp:
> +		return spd5118_temp_write(regmap, attr, val);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static umode_t spd5118_is_visible(const void *_data, enum hwmon_sensor_types type,
> +				  u32 attr, int channel)
> +{
> +	if (type != hwmon_temp)
> +		return 0;
> +
> +	switch (attr) {
> +	case hwmon_temp_input:
> +		return 0444;
> +	case hwmon_temp_min:
> +	case hwmon_temp_max:
> +	case hwmon_temp_lcrit:
> +	case hwmon_temp_crit:
> +	case hwmon_temp_enable:
> +		return 0644;
> +	case hwmon_temp_min_alarm:
> +	case hwmon_temp_max_alarm:
> +	case hwmon_temp_crit_alarm:
> +	case hwmon_temp_lcrit_alarm:
> +		return 0444;
> +	default:
> +		return 0;
> +	}
> +}
> +
> +static inline bool spd5118_parity8(u8 w)
> +{
> +	w ^= w >> 4;
> +	return (0x6996 >> (w & 0xf)) & 1;
> +}
> +
> +/*
> + * Bank and vendor id are 8-bit fields with seven data bits and odd parity.
> + * Vendor IDs 0 and 0x7f are invalid.
> + * See Jedec standard JEP106BJ for details and a list of assigned vendor IDs.
> + */
> +static bool spd5118_vendor_valid(u8 bank, u8 id)
> +{
> +	if (!spd5118_parity8(bank) || !spd5118_parity8(id))
> +		return false;
> +
> +	id &= 0x7f;
> +	return id && id != 0x7f;
> +}
> +
> +/* Return 0 if detection is successful, -ENODEV otherwise */
> +static int spd5118_detect(struct i2c_client *client, struct i2c_board_info *info)
> +{
> +	struct i2c_adapter *adapter = client->adapter;
> +	int regval;
> +
> +	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
> +				     I2C_FUNC_SMBUS_WORD_DATA))
> +		return -ENODEV;
> +
> +	regval = i2c_smbus_read_word_swapped(client, SPD5118_REG_TYPE);
> +	if (regval != 0x5118)
> +		return -ENODEV;
> +
> +	regval = i2c_smbus_read_word_data(client, SPD5118_REG_VENDOR);
> +	if (regval < 0 || !spd5118_vendor_valid(regval & 0xff, regval >> 8))
> +		return -ENODEV;
> +
> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_CAPABILITY);
> +	if (regval < 0)
> +		return -ENODEV;
> +	if (!(regval & SPD5118_CAP_TS_SUPPORT) || (regval & 0xfc))
> +		return -ENODEV;
> +
> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_TEMP_CLR);
> +	if (regval)
> +		return -ENODEV;
> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_ERROR_CLR);
> +	if (regval)
> +		return -ENODEV;
> +
> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_REVISION);
> +	if (regval < 0 || (regval & 0xc1))
> +		return -ENODEV;
> +
> +	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_TEMP_CONFIG);
> +	if (regval < 0)
> +		return -ENODEV;
> +	if (regval & ~SPD5118_TS_DISABLE)
> +		return -ENODEV;
> +
> +	strscpy(info->type, "spd5118", I2C_NAME_SIZE);
> +	return 0;
> +}
> +
> +static const struct hwmon_channel_info *spd5118_info[] = {
> +	HWMON_CHANNEL_INFO(chip,
> +			   HWMON_C_REGISTER_TZ),
> +	HWMON_CHANNEL_INFO(temp,
> +			   HWMON_T_INPUT |
> +			   HWMON_T_LCRIT | HWMON_T_LCRIT_ALARM |
> +			   HWMON_T_MIN | HWMON_T_MIN_ALARM |
> +			   HWMON_T_MAX | HWMON_T_MAX_ALARM |
> +			   HWMON_T_CRIT | HWMON_T_CRIT_ALARM |
> +			   HWMON_T_ENABLE),
> +	NULL
> +};
> +
> +static const struct hwmon_ops spd5118_hwmon_ops = {
> +	.is_visible = spd5118_is_visible,
> +	.read = spd5118_read,
> +	.write = spd5118_write,
> +};
> +
> +static const struct hwmon_chip_info spd5118_chip_info = {
> +	.ops = &spd5118_hwmon_ops,
> +	.info = spd5118_info,
> +};
> +
> +static bool spd5118_writeable_reg(struct device *dev, unsigned int reg)
> +{
> +	switch (reg) {
> +	case SPD5118_REG_TEMP_CLR:
> +	case SPD5118_REG_TEMP_CONFIG:
> +	case SPD5118_REG_TEMP_MAX:
> +	case SPD5118_REG_TEMP_MAX + 1:
> +	case SPD5118_REG_TEMP_MIN:
> +	case SPD5118_REG_TEMP_MIN + 1:
> +	case SPD5118_REG_TEMP_CRIT:
> +	case SPD5118_REG_TEMP_CRIT + 1:
> +	case SPD5118_REG_TEMP_LCRIT:
> +	case SPD5118_REG_TEMP_LCRIT + 1:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +static bool spd5118_volatile_reg(struct device *dev, unsigned int reg)
> +{
> +	switch (reg) {
> +	case SPD5118_REG_TEMP_CLR:
> +	case SPD5118_REG_ERROR_CLR:
> +	case SPD5118_REG_TEMP:
> +	case SPD5118_REG_TEMP + 1:
> +	case SPD5118_REG_TEMP_STATUS:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +static const struct regmap_config spd5118_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.max_register = SPD5118_REG_TEMP_STATUS,
> +	.writeable_reg = spd5118_writeable_reg,
> +	.volatile_reg = spd5118_volatile_reg,
> +	.cache_type = REGCACHE_MAPLE,
> +};
> +
> +static int spd5118_probe(struct i2c_client *client)
> +{
> +	struct device *dev = &client->dev;
> +	unsigned int regval, revision, vendor, bank;
> +	struct device *hwmon_dev;
> +	struct regmap *regmap;
> +	int err;
> +
> +	regmap = devm_regmap_init_i2c(client, &spd5118_regmap_config);
> +	if (IS_ERR(regmap))
> +		return dev_err_probe(dev, PTR_ERR(regmap), "regmap init failed\n");
> +
> +	err = regmap_read(regmap, SPD5118_REG_CAPABILITY, &regval);
> +	if (err)
> +		return err;
> +	if (!(regval & SPD5118_CAP_TS_SUPPORT))
> +		return -ENODEV;
> +
> +	err = regmap_read(regmap, SPD5118_REG_REVISION, &revision);
> +	if (err)
> +		return err;
> +
> +	err = regmap_read(regmap, SPD5118_REG_VENDOR, &bank);
> +	if (err)
> +		return err;
> +	err = regmap_read(regmap, SPD5118_REG_VENDOR + 1, &vendor);
> +	if (err)
> +		return err;
> +	if (!spd5118_vendor_valid(bank, vendor))
> +		return -ENODEV;
> +
> +	hwmon_dev = devm_hwmon_device_register_with_info(dev, "spd5118",
> +							 regmap, &spd5118_chip_info,
> +							 NULL);
> +	if (IS_ERR(hwmon_dev))
> +		return PTR_ERR(hwmon_dev);
> +
> +	/*
> +	 * From JESD300-5B
> +	 *   MR2 bits [5:4]: Major revision, 1..4
> +	 *   MR2 bits [3:1]: Minor revision, 0..8? Probably a typo, assume 1..8
> +	 */
> +	dev_info(dev, "DDR5 temperature sensor: vendor 0x%02x:0x%02x revision %d.%d\n",
> +		 bank & 0x7f, vendor, ((revision >> 4) & 0x03) + 1, ((revision >> 1) & 0x07) + 1);
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id spd5118_id[] = {
> +	{ "spd5118", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, spd5118_id);
> +
> +static const struct of_device_id spd5118_of_ids[] = {
> +	{ .compatible = "jedec,spd5118", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, spd5118_of_ids);
> +
> +static struct i2c_driver spd5118_driver = {
> +	.class		= I2C_CLASS_HWMON,
> +	.driver = {
> +		.name	= "spd5118",
> +		.of_match_table = spd5118_of_ids,
> +	},
> +	.probe		= spd5118_probe,
> +	.id_table	= spd5118_id,
> +	.detect		= spd5118_detect,
> +	.address_list	= normal_i2c,
> +};
> +
> +module_i2c_driver(spd5118_driver);
> +
> +MODULE_AUTHOR("René Rebe <[e-mail]>");
> +MODULE_AUTHOR("Guenter Roeck <[e-mail]>");
> +MODULE_DESCRIPTION("SPD 5118 driver");
> +MODULE_LICENSE("GPL");

Wolfram Sang June 2, 2024, 8:18 p.m. UTC | #4

> would introduce a cross-subsystem dependency. Of course, that depends a bit
> on your position about such dependencies. If I do that as part of this series,
> would you Ack it, or would you want to handle that through the i2c tree ?

I would ack it. If I'd have a conflicting commit in my tree (unlikely),
I'd ask you for an immutable branch to pull into my tree.

Guenter Roeck June 2, 2024, 9:24 p.m. UTC | #5

On 6/2/24 13:18, Wolfram Sang wrote:
> 
>> would introduce a cross-subsystem dependency. Of course, that depends a bit
>> on your position about such dependencies. If I do that as part of this series,
>> would you Ack it, or would you want to handle that through the i2c tree ?
> 
> I would ack it. If I'd have a conflicting commit in my tree (unlikely),
> I'd ask you for an immutable branch to pull into my tree.
> 

Sounds good.

Turns out we can not entirely remove the detect code anyway.
i2c_register_spd() depends on DMI support, which is not a given
on all systems supporting DDR5, and it is limited to a maximum
of 8 memory modules. I'll try to make it conditional with a
configuration option.

Thanks,
Guenter

Patch

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 03d313af469a..6e7b8726b60c 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -215,6 +215,7 @@  Hardware Monitoring Kernel Drivers
    smsc47m192
    smsc47m1
    sparx5-temp
+   spd5118
    stpddc60
    surface_fan
    sy7636a-hwmon
diff --git a/Documentation/hwmon/spd5118.rst b/Documentation/hwmon/spd5118.rst
new file mode 100644
index 000000000000..a15d75aa2066
--- /dev/null
+++ b/Documentation/hwmon/spd5118.rst
@@ -0,0 +1,55 @@ 
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Kernel driver spd5118
+=====================
+
+Supported chips:
+
+  * SPD5118 (JEDEC JESD300) compliant temperature sensor chips
+
+    JEDEC standard download:
+	https://www.jedec.org/standards-documents/docs/jesd300-5b01
+	(account required)
+
+
+    Prefix: 'spd5118'
+
+    Addresses scanned: I2C 0x50 - 0x57
+
+Author:
+	Guenter Roeck <[e-mail]>
+
+
+Description
+-----------
+
+This driver implements support for SPD5118 (JEDEC JESD300) compliant temperature
+sensors, which are used on many DDR5 memory modules. Some systems use the sensor
+to prevent memory overheating by automatically throttling the memory controller.
+
+The driver auto-detects SPD5118 compliant chips, but can also be instantiated
+using devicetree/firmware nodes.
+
+A SPD5118 compliant chip supports a single temperature sensor. Critical minimum,
+minimum, maximum, and critical temperature can be configured. There are alarms
+for low critical, low, high, and critical thresholds.
+
+
+Hardware monitoring sysfs entries
+---------------------------------
+
+======================= ==================================
+temp1_input		Temperature (RO)
+temp1_lcrit		Low critical high temperature (RW)
+temp1_min		Minimum temperature (RW)
+temp1_max		Maximum temperature (RW)
+temp1_crit		Critical high temperature (RW)
+
+temp1_lcrit_alarm	Temperature low critical alarm
+temp1_min_alarm		Temperature low alarm
+temp1_max_alarm		Temperature high alarm
+temp1_crit_alarm	Temperature critical alarm
+======================= ==================================
+
+Alarm attributes are sticky until read and will be cleared afterwards
+unless the alarm condition still applies.
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index e14ae18a973b..d0fb5fe1b2ac 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -2181,6 +2181,18 @@  config SENSORS_INA3221
 	  This driver can also be built as a module. If so, the module
 	  will be called ina3221.
 
+config SENSORS_SPD5118
+	tristate "SPD5118 Compliant Temperature Sensors"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for SPD5118 (JEDEC JESD300)
+	  compliant temperature sensors. Such sensors are found on DDR5 memory
+	  modules.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called spd5118.
+
 config SENSORS_TC74
 	tristate "Microchip TC74"
 	depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index e3f25475d1f0..6574ca67d761 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -207,6 +207,7 @@  obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o
 obj-$(CONFIG_SENSORS_SMSC47M1)	+= smsc47m1.o
 obj-$(CONFIG_SENSORS_SMSC47M192)+= smsc47m192.o
 obj-$(CONFIG_SENSORS_SPARX5)	+= sparx5-temp.o
+obj-$(CONFIG_SENSORS_SPD5118)	+= spd5118.o
 obj-$(CONFIG_SENSORS_STTS751)	+= stts751.o
 obj-$(CONFIG_SENSORS_SURFACE_FAN)+= surface_fan.o
 obj-$(CONFIG_SENSORS_SY7636A)	+= sy7636a-hwmon.o
diff --git a/drivers/hwmon/spd5118.c b/drivers/hwmon/spd5118.c
new file mode 100644
index 000000000000..d3fc0ae17743
--- /dev/null
+++ b/drivers/hwmon/spd5118.c
@@ -0,0 +1,481 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for Jedec 5118 compliant temperature sensors
+ *
+ * Derived from https://github.com/Steve-Tech/SPD5118-DKMS
+ * Originally from T/2 driver at https://t2sde.org/packages/linux
+ *	Copyright (c) 2023 René Rebe, ExactCODE GmbH; Germany.
+ *
+ * Copyright (c) 2024 Guenter Roeck
+ *
+ * Inspired by ee1004.c and jc42.c.
+ *
+ * SPD5118 compliant temperature sensors are typically used on DDR5
+ * memory modules.
+ */
+
+#include <linux/bitops.h>
+#include <linux/bits.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/units.h>
+
+/* Addresses to scan */
+static const unsigned short normal_i2c[] = {
+	0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, I2C_CLIENT_END };
+
+/* SPD5118 registers. */
+#define SPD5118_REG_TYPE		0x00	/* MR0:MR1 */
+#define SPD5118_REG_REVISION		0x02	/* MR2 */
+#define SPD5118_REG_VENDOR		0x03	/* MR3:MR4 */
+#define SPD5118_REG_CAPABILITY		0x05	/* MR5 */
+#define SPD5118_REG_I2C_LEGACY_MODE	0x0B	/* MR11 */
+#define SPD5118_REG_TEMP_CLR		0x13	/* MR19 */
+#define SPD5118_REG_ERROR_CLR		0x14	/* MR20 */
+#define SPD5118_REG_TEMP_CONFIG		0x1A	/* MR26 */
+#define SPD5118_REG_TEMP_MAX		0x1c	/* MR28:MR29 */
+#define SPD5118_REG_TEMP_MIN		0x1e	/* MR30:MR31 */
+#define SPD5118_REG_TEMP_CRIT		0x20	/* MR32:MR33 */
+#define SPD5118_REG_TEMP_LCRIT		0x22	/* MR34:MR35 */
+#define SPD5118_REG_TEMP		0x31	/* MR49:MR50 */
+#define SPD5118_REG_TEMP_STATUS		0x33	/* MR51 */
+
+#define SPD5118_TEMP_STATUS_HIGH	BIT(0)
+#define SPD5118_TEMP_STATUS_LOW		BIT(1)
+#define SPD5118_TEMP_STATUS_CRIT	BIT(2)
+#define SPD5118_TEMP_STATUS_LCRIT	BIT(3)
+
+#define SPD5118_CAP_TS_SUPPORT		BIT(1)	/* temperature sensor support */
+
+#define SPD5118_TS_DISABLE		BIT(0)	/* temperature sensor disable */
+
+/* Temperature unit in millicelsius */
+#define SPD5118_TEMP_UNIT		(MILLIDEGREE_PER_DEGREE / 4)
+/* Representable temperature range in millicelsius */
+#define SPD5118_TEMP_RANGE_MIN		-256000
+#define SPD5118_TEMP_RANGE_MAX		255750
+
+static int spd5118_temp_from_reg(u16 reg)
+{
+	int temp = sign_extend32(reg >> 2, 10);
+
+	return temp * SPD5118_TEMP_UNIT;
+}
+
+static u16 spd5118_temp_to_reg(long temp)
+{
+	temp = clamp_val(temp, SPD5118_TEMP_RANGE_MIN, SPD5118_TEMP_RANGE_MAX);
+	return (DIV_ROUND_CLOSEST(temp, SPD5118_TEMP_UNIT) & 0x7ff) << 2;
+}
+
+static int spd5118_read_temp(struct regmap *regmap, u32 attr, long *val)
+{
+	int reg, err;
+	u8 regval[2];
+	u16 temp;
+
+	switch (attr) {
+	case hwmon_temp_input:
+		reg = SPD5118_REG_TEMP;
+		break;
+	case hwmon_temp_max:
+		reg = SPD5118_REG_TEMP_MAX;
+		break;
+	case hwmon_temp_min:
+		reg = SPD5118_REG_TEMP_MIN;
+		break;
+	case hwmon_temp_crit:
+		reg = SPD5118_REG_TEMP_CRIT;
+		break;
+	case hwmon_temp_lcrit:
+		reg = SPD5118_REG_TEMP_LCRIT;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	err = regmap_bulk_read(regmap, reg, regval, 2);
+	if (err)
+		return err;
+
+	temp = (regval[1] << 8) | regval[0];
+
+	*val = spd5118_temp_from_reg(temp);
+	return 0;
+}
+
+static int spd5118_read_alarm(struct regmap *regmap, u32 attr, long *val)
+{
+	unsigned int mask, regval;
+	int err;
+
+	switch (attr) {
+	case hwmon_temp_max_alarm:
+		mask = SPD5118_TEMP_STATUS_HIGH;
+		break;
+	case hwmon_temp_min_alarm:
+		mask = SPD5118_TEMP_STATUS_LOW;
+		break;
+	case hwmon_temp_crit_alarm:
+		mask = SPD5118_TEMP_STATUS_CRIT;
+		break;
+	case hwmon_temp_lcrit_alarm:
+		mask = SPD5118_TEMP_STATUS_LCRIT;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	err = regmap_read(regmap, SPD5118_REG_TEMP_STATUS, &regval);
+	if (err < 0)
+		return err;
+	*val = !!(regval & mask);
+	if (*val)
+		return regmap_write(regmap, SPD5118_REG_TEMP_CLR, mask);
+	return 0;
+}
+
+static int spd5118_read_enable(struct regmap *regmap, long *val)
+{
+	u32 regval;
+	int err;
+
+	err = regmap_read(regmap, SPD5118_REG_TEMP_CONFIG, &regval);
+	if (err < 0)
+		return err;
+	*val = !(regval & SPD5118_TS_DISABLE);
+	return 0;
+}
+
+static int spd5118_read(struct device *dev, enum hwmon_sensor_types type,
+			u32 attr, int channel, long *val)
+{
+	struct regmap *regmap = dev_get_drvdata(dev);
+
+	if (type != hwmon_temp)
+		return -EOPNOTSUPP;
+
+	switch (attr) {
+	case hwmon_temp_input:
+	case hwmon_temp_max:
+	case hwmon_temp_min:
+	case hwmon_temp_crit:
+	case hwmon_temp_lcrit:
+		return spd5118_read_temp(regmap, attr, val);
+	case hwmon_temp_max_alarm:
+	case hwmon_temp_min_alarm:
+	case hwmon_temp_crit_alarm:
+	case hwmon_temp_lcrit_alarm:
+		return spd5118_read_alarm(regmap, attr, val);
+	case hwmon_temp_enable:
+		return spd5118_read_enable(regmap, val);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int spd5118_write_temp(struct regmap *regmap, u32 attr, long val)
+{
+	u8 regval[2];
+	u16 temp;
+	int reg;
+
+	switch (attr) {
+	case hwmon_temp_max:
+		reg = SPD5118_REG_TEMP_MAX;
+		break;
+	case hwmon_temp_min:
+		reg = SPD5118_REG_TEMP_MIN;
+		break;
+	case hwmon_temp_crit:
+		reg = SPD5118_REG_TEMP_CRIT;
+		break;
+	case hwmon_temp_lcrit:
+		reg = SPD5118_REG_TEMP_LCRIT;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	temp = spd5118_temp_to_reg(val);
+	regval[0] = temp & 0xff;
+	regval[1] = temp >> 8;
+
+	return regmap_bulk_write(regmap, reg, regval, 2);
+}
+
+static int spd5118_write_enable(struct regmap *regmap, long val)
+{
+	if (val && val != 1)
+		return -EINVAL;
+
+	return regmap_update_bits(regmap, SPD5118_REG_TEMP_CONFIG,
+				  SPD5118_TS_DISABLE,
+				  val ? 0 : SPD5118_TS_DISABLE);
+}
+
+static int spd5118_temp_write(struct regmap *regmap, u32 attr, long val)
+{
+	switch (attr) {
+	case hwmon_temp_max:
+	case hwmon_temp_min:
+	case hwmon_temp_crit:
+	case hwmon_temp_lcrit:
+		return spd5118_write_temp(regmap, attr, val);
+	case hwmon_temp_enable:
+		return spd5118_write_enable(regmap, val);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int spd5118_write(struct device *dev, enum hwmon_sensor_types type,
+			 u32 attr, int channel, long val)
+{
+	struct regmap *regmap = dev_get_drvdata(dev);
+
+	switch (type) {
+	case hwmon_temp:
+		return spd5118_temp_write(regmap, attr, val);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static umode_t spd5118_is_visible(const void *_data, enum hwmon_sensor_types type,
+				  u32 attr, int channel)
+{
+	if (type != hwmon_temp)
+		return 0;
+
+	switch (attr) {
+	case hwmon_temp_input:
+		return 0444;
+	case hwmon_temp_min:
+	case hwmon_temp_max:
+	case hwmon_temp_lcrit:
+	case hwmon_temp_crit:
+	case hwmon_temp_enable:
+		return 0644;
+	case hwmon_temp_min_alarm:
+	case hwmon_temp_max_alarm:
+	case hwmon_temp_crit_alarm:
+	case hwmon_temp_lcrit_alarm:
+		return 0444;
+	default:
+		return 0;
+	}
+}
+
+static inline bool spd5118_parity8(u8 w)
+{
+	w ^= w >> 4;
+	return (0x6996 >> (w & 0xf)) & 1;
+}
+
+/*
+ * Bank and vendor id are 8-bit fields with seven data bits and odd parity.
+ * Vendor IDs 0 and 0x7f are invalid.
+ * See Jedec standard JEP106BJ for details and a list of assigned vendor IDs.
+ */
+static bool spd5118_vendor_valid(u8 bank, u8 id)
+{
+	if (!spd5118_parity8(bank) || !spd5118_parity8(id))
+		return false;
+
+	id &= 0x7f;
+	return id && id != 0x7f;
+}
+
+/* Return 0 if detection is successful, -ENODEV otherwise */
+static int spd5118_detect(struct i2c_client *client, struct i2c_board_info *info)
+{
+	struct i2c_adapter *adapter = client->adapter;
+	int regval;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
+				     I2C_FUNC_SMBUS_WORD_DATA))
+		return -ENODEV;
+
+	regval = i2c_smbus_read_word_swapped(client, SPD5118_REG_TYPE);
+	if (regval != 0x5118)
+		return -ENODEV;
+
+	regval = i2c_smbus_read_word_data(client, SPD5118_REG_VENDOR);
+	if (regval < 0 || !spd5118_vendor_valid(regval & 0xff, regval >> 8))
+		return -ENODEV;
+
+	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_CAPABILITY);
+	if (regval < 0)
+		return -ENODEV;
+	if (!(regval & SPD5118_CAP_TS_SUPPORT) || (regval & 0xfc))
+		return -ENODEV;
+
+	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_TEMP_CLR);
+	if (regval)
+		return -ENODEV;
+	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_ERROR_CLR);
+	if (regval)
+		return -ENODEV;
+
+	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_REVISION);
+	if (regval < 0 || (regval & 0xc1))
+		return -ENODEV;
+
+	regval = i2c_smbus_read_byte_data(client, SPD5118_REG_TEMP_CONFIG);
+	if (regval < 0)
+		return -ENODEV;
+	if (regval & ~SPD5118_TS_DISABLE)
+		return -ENODEV;
+
+	strscpy(info->type, "spd5118", I2C_NAME_SIZE);
+	return 0;
+}
+
+static const struct hwmon_channel_info *spd5118_info[] = {
+	HWMON_CHANNEL_INFO(chip,
+			   HWMON_C_REGISTER_TZ),
+	HWMON_CHANNEL_INFO(temp,
+			   HWMON_T_INPUT |
+			   HWMON_T_LCRIT | HWMON_T_LCRIT_ALARM |
+			   HWMON_T_MIN | HWMON_T_MIN_ALARM |
+			   HWMON_T_MAX | HWMON_T_MAX_ALARM |
+			   HWMON_T_CRIT | HWMON_T_CRIT_ALARM |
+			   HWMON_T_ENABLE),
+	NULL
+};
+
+static const struct hwmon_ops spd5118_hwmon_ops = {
+	.is_visible = spd5118_is_visible,
+	.read = spd5118_read,
+	.write = spd5118_write,
+};
+
+static const struct hwmon_chip_info spd5118_chip_info = {
+	.ops = &spd5118_hwmon_ops,
+	.info = spd5118_info,
+};
+
+static bool spd5118_writeable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case SPD5118_REG_TEMP_CLR:
+	case SPD5118_REG_TEMP_CONFIG:
+	case SPD5118_REG_TEMP_MAX:
+	case SPD5118_REG_TEMP_MAX + 1:
+	case SPD5118_REG_TEMP_MIN:
+	case SPD5118_REG_TEMP_MIN + 1:
+	case SPD5118_REG_TEMP_CRIT:
+	case SPD5118_REG_TEMP_CRIT + 1:
+	case SPD5118_REG_TEMP_LCRIT:
+	case SPD5118_REG_TEMP_LCRIT + 1:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool spd5118_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case SPD5118_REG_TEMP_CLR:
+	case SPD5118_REG_ERROR_CLR:
+	case SPD5118_REG_TEMP:
+	case SPD5118_REG_TEMP + 1:
+	case SPD5118_REG_TEMP_STATUS:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_config spd5118_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = SPD5118_REG_TEMP_STATUS,
+	.writeable_reg = spd5118_writeable_reg,
+	.volatile_reg = spd5118_volatile_reg,
+	.cache_type = REGCACHE_MAPLE,
+};
+
+static int spd5118_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	unsigned int regval, revision, vendor, bank;
+	struct device *hwmon_dev;
+	struct regmap *regmap;
+	int err;
+
+	regmap = devm_regmap_init_i2c(client, &spd5118_regmap_config);
+	if (IS_ERR(regmap))
+		return dev_err_probe(dev, PTR_ERR(regmap), "regmap init failed\n");
+
+	err = regmap_read(regmap, SPD5118_REG_CAPABILITY, &regval);
+	if (err)
+		return err;
+	if (!(regval & SPD5118_CAP_TS_SUPPORT))
+		return -ENODEV;
+
+	err = regmap_read(regmap, SPD5118_REG_REVISION, &revision);
+	if (err)
+		return err;
+
+	err = regmap_read(regmap, SPD5118_REG_VENDOR, &bank);
+	if (err)
+		return err;
+	err = regmap_read(regmap, SPD5118_REG_VENDOR + 1, &vendor);
+	if (err)
+		return err;
+	if (!spd5118_vendor_valid(bank, vendor))
+		return -ENODEV;
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, "spd5118",
+							 regmap, &spd5118_chip_info,
+							 NULL);
+	if (IS_ERR(hwmon_dev))
+		return PTR_ERR(hwmon_dev);
+
+	/*
+	 * From JESD300-5B
+	 *   MR2 bits [5:4]: Major revision, 1..4
+	 *   MR2 bits [3:1]: Minor revision, 0..8? Probably a typo, assume 1..8
+	 */
+	dev_info(dev, "DDR5 temperature sensor: vendor 0x%02x:0x%02x revision %d.%d\n",
+		 bank & 0x7f, vendor, ((revision >> 4) & 0x03) + 1, ((revision >> 1) & 0x07) + 1);
+
+	return 0;
+}
+
+static const struct i2c_device_id spd5118_id[] = {
+	{ "spd5118", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, spd5118_id);
+
+static const struct of_device_id spd5118_of_ids[] = {
+	{ .compatible = "jedec,spd5118", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, spd5118_of_ids);
+
+static struct i2c_driver spd5118_driver = {
+	.class		= I2C_CLASS_HWMON,
+	.driver = {
+		.name	= "spd5118",
+		.of_match_table = spd5118_of_ids,
+	},
+	.probe		= spd5118_probe,
+	.id_table	= spd5118_id,
+	.detect		= spd5118_detect,
+	.address_list	= normal_i2c,
+};
+
+module_i2c_driver(spd5118_driver);
+
+MODULE_AUTHOR("René Rebe <[e-mail]>");
+MODULE_AUTHOR("Guenter Roeck <[e-mail]>");
+MODULE_DESCRIPTION("SPD 5118 driver");
+MODULE_LICENSE("GPL");