diff mbox

[v5,1/2] hwmon: new driver for ST stts751 thermal sensor

Message ID 1485769255-27118-1-git-send-email-andrea.merello@gmail.com (mailing list archive)
State Superseded
Headers show

Commit Message

Andrea Merello Jan. 30, 2017, 9:40 a.m. UTC
This patch adds a HWMON driver for ST Microelectronics STTS751
temperature sensors.

Changes since V3:
- fix sysfs_notify() filename
- simplify error exit path in stts751_update_temp(): kill useless goto
- fix set function were racy due to lock incorrectly placed
- use msecs_to_jiffies instead of manual calculation
- fix jiffies and msecs were mixed up
- don't mark cache as good unless reads really succeded to fill up it
- when updating therm, hyst keeps relative value rather than abs value
- don't should in dev_dbg when chip is detected
- don't ever generate two uevents
- clarify clear-on-read behaviour of status reg alarm flags
- simplify mDEG to HW conversion function
- fix chip stops due to incorrect resolution configuration
- fix incorrectly reading negative numbers from HW

Changes since V4:
- fix continuation lines (style, remove uncecessary, ..)
- shorten a unnecessary verbose dev_warn() message
- fix set_interval() exitpath didn't return error
- change uncecesary neg-logic
- change file symbolic permissions with octal
- move chip revision test in probe(), change dev_notice() in dev_dbg()
- use "return 0" on success (non functional change)
- add further checks in i2c detect function
- fix i2c detect function read wrong reg while checking for manufacturer ID

Thanks-to: LABBE Corentin [for suggestions]
Thanks-to: Guenter Roeck [for suggestion and discussions]
Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
Cc: LABBE Corentin <clabbe.montjoie@gmail.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Jean Delvare <jdelvare@suse.com>
---
 drivers/hwmon/Kconfig   |  10 +
 drivers/hwmon/Makefile  |   1 +
 drivers/hwmon/stts751.c | 819 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 830 insertions(+)
 create mode 100644 drivers/hwmon/stts751.c

Comments

Guenter Roeck Jan. 30, 2017, 2:24 p.m. UTC | #1
On 01/30/2017 01:40 AM, Andrea Merello wrote:
> This patch adds a HWMON driver for ST Microelectronics STTS751
> temperature sensors.
>

Overall looks good. One thing I noticed, though: In the log function calls,
you use a mix of priv->dev and &client->dev as log device. Also, you sometimes
use &priv->client->dev even when a local client variable is available.
I can fix up the latter (no need to resend for that), but please have a
look at the overall use and either send a fixed up version or let me know
if the log devices are all intentional as-is.

Thanks,
Guenter

> Changes since V3:
> - fix sysfs_notify() filename
> - simplify error exit path in stts751_update_temp(): kill useless goto
> - fix set function were racy due to lock incorrectly placed
> - use msecs_to_jiffies instead of manual calculation
> - fix jiffies and msecs were mixed up
> - don't mark cache as good unless reads really succeded to fill up it
> - when updating therm, hyst keeps relative value rather than abs value
> - don't should in dev_dbg when chip is detected
> - don't ever generate two uevents
> - clarify clear-on-read behaviour of status reg alarm flags
> - simplify mDEG to HW conversion function
> - fix chip stops due to incorrect resolution configuration
> - fix incorrectly reading negative numbers from HW
>
> Changes since V4:
> - fix continuation lines (style, remove uncecessary, ..)
> - shorten a unnecessary verbose dev_warn() message
> - fix set_interval() exitpath didn't return error
> - change uncecesary neg-logic
> - change file symbolic permissions with octal
> - move chip revision test in probe(), change dev_notice() in dev_dbg()
> - use "return 0" on success (non functional change)
> - add further checks in i2c detect function
> - fix i2c detect function read wrong reg while checking for manufacturer ID
>
> Thanks-to: LABBE Corentin [for suggestions]
> Thanks-to: Guenter Roeck [for suggestion and discussions]
> Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
> Cc: LABBE Corentin <clabbe.montjoie@gmail.com>
> Cc: Guenter Roeck <linux@roeck-us.net>
> Cc: Jean Delvare <jdelvare@suse.com>
> ---
>  drivers/hwmon/Kconfig   |  10 +
>  drivers/hwmon/Makefile  |   1 +
>  drivers/hwmon/stts751.c | 819 ++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 830 insertions(+)
>  create mode 100644 drivers/hwmon/stts751.c
>
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index d1f82f2..8fdd241 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -1448,6 +1448,16 @@ config SENSORS_SCH5636
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called sch5636.
>
> +config SENSORS_STTS751
> +	tristate "ST Microelectronics STTS751"
> +	depends on I2C
> +	help
> +	  If you say yes here you get support for STTS751
> +	  temperature sensor chips.
> +
> +	  This driver can also be built as a module.  If so, the module
> +	  will be called stts751.
> +
>  config SENSORS_SMM665
>  	tristate "Summit Microelectronics SMM665"
>  	depends on I2C
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 7476b22..1114130 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -147,6 +147,7 @@ obj-$(CONFIG_SENSORS_SMM665)	+= smm665.o
>  obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o
>  obj-$(CONFIG_SENSORS_SMSC47M1)	+= smsc47m1.o
>  obj-$(CONFIG_SENSORS_SMSC47M192)+= smsc47m192.o
> +obj-$(CONFIG_SENSORS_STTS751)	+= stts751.o
>  obj-$(CONFIG_SENSORS_AMC6821)	+= amc6821.o
>  obj-$(CONFIG_SENSORS_TC74)	+= tc74.o
>  obj-$(CONFIG_SENSORS_THMC50)	+= thmc50.o
> diff --git a/drivers/hwmon/stts751.c b/drivers/hwmon/stts751.c
> new file mode 100644
> index 0000000..4154294
> --- /dev/null
> +++ b/drivers/hwmon/stts751.c
> @@ -0,0 +1,819 @@
> +/*
> + * STTS751 sensor driver
> + *
> + * Copyright (C) 2016-2017 Istituto Italiano di Tecnologia - RBCS - EDL
> + * Robotics, Brain and Cognitive Sciences department
> + * Electronic Design Laboratory
> + *
> + * Written by Andrea Merello <andrea.merello@gmail.com>
> + *
> + * Based on  LM95241 driver and LM90 driver
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/err.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/i2c.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/jiffies.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/property.h>
> +#include <linux/slab.h>
> +#include <linux/sysfs.h>
> +#include <linux/util_macros.h>
> +
> +#define DEVNAME "stts751"
> +
> +static const unsigned short normal_i2c[] = {
> +	0x48, 0x49, 0x38, 0x39,  /* STTS751-0 */
> +	0x4A, 0x4B, 0x3A, 0x3B,  /* STTS751-1 */
> +	I2C_CLIENT_END };
> +
> +#define STTS751_REG_TEMP_H	0x00
> +#define STTS751_REG_STATUS	0x01
> +#define STTS751_STATUS_TRIPT	BIT(0)
> +#define STTS751_STATUS_TRIPL	BIT(5)
> +#define STTS751_STATUS_TRIPH	BIT(6)
> +#define STTS751_REG_TEMP_L	0x02
> +#define STTS751_REG_CONF	0x03
> +#define STTS751_CONF_RES_MASK	0x0C
> +#define STTS751_CONF_RES_SHIFT  2
> +#define STTS751_CONF_EVENT_DIS  BIT(7)
> +#define STTS751_CONF_STOP	BIT(6)
> +#define STTS751_REG_RATE	0x04
> +#define STTS751_REG_HLIM_H	0x05
> +#define STTS751_REG_HLIM_L	0x06
> +#define STTS751_REG_LLIM_H	0x07
> +#define STTS751_REG_LLIM_L	0x08
> +#define STTS751_REG_TLIM	0x20
> +#define STTS751_REG_HYST	0x21
> +#define STTS751_REG_SMBUS_TO	0x22
> +
> +#define STTS751_REG_PROD_ID	0xFD
> +#define STTS751_REG_MAN_ID	0xFE
> +#define STTS751_REG_REV_ID	0xFF
> +
> +#define STTS751_0_PROD_ID	0x00
> +#define STTS751_1_PROD_ID	0x01
> +#define ST_MAN_ID		0x53
> +
> +/*
> + * Possible update intervals are (in mS):
> + * 16000, 8000, 4000, 2000, 1000, 500, 250, 125, 62.5, 31.25
> + * However we are not going to complicate things too much and we stick to the
> + * approx value in mS.
> + */
> +static const int stts751_intervals[] = {
> +	16000, 8000, 4000, 2000, 1000, 500, 250, 125, 63, 31
> +};
> +
> +static const struct i2c_device_id stts751_id[] = {
> +	{ "stts751", 0 },
> +	{ }
> +};
> +
> +struct stts751_priv {
> +	struct device *dev;
> +	struct i2c_client *client;
> +	struct mutex access_lock;
> +	u8 interval;
> +	int res;
> +	int event_max, event_min;
> +	int therm;
> +	int hyst;
> +	bool smbus_timeout;
> +	int temp;
> +	unsigned long last_update, last_alert_update;
> +	u8 config;
> +	bool min_alert, max_alert, therm_trip;
> +	bool data_valid, alert_valid;
> +};
> +
> +/*
> + * These functions converts temperature from HW format to integer format and
> + * vice-vers. They are (mostly) taken from lm90 driver. Unit is in mC.
> + */
> +static int stts751_to_deg(s16 hw_val)
> +{
> +	return hw_val * 125 / 32;
> +}
> +
> +static s32 stts751_to_hw(int val)
> +{
> +	return DIV_ROUND_CLOSEST(val, 125) * 32;
> +}
> +
> +static int stts751_adjust_resolution(struct stts751_priv *priv)
> +{
> +	u8 res;
> +
> +	switch (priv->interval) {
> +	case 9:
> +		/* 10 bits */
> +		res = 0;
> +		break;
> +	case 8:
> +		/* 11 bits */
> +		res = 1;
> +		break;
> +	default:
> +		/* 12 bits */
> +		res = 3;
> +		break;
> +	}
> +
> +	if (priv->res == res)
> +		return 0;
> +
> +	priv->config &= ~STTS751_CONF_RES_MASK;
> +	priv->config |= res << STTS751_CONF_RES_SHIFT;
> +	dev_dbg(priv->dev, "setting res %d. config %x", res, priv->config);
> +	priv->res = res;
> +
> +	return i2c_smbus_write_byte_data(priv->client,
> +				STTS751_REG_CONF, priv->config);
> +}
> +
> +static int stts751_update_temp(struct stts751_priv *priv)
> +{
> +	s32 integer1, integer2, frac;
> +
> +	/*
> +	 * There is a trick here, like in the lm90 driver. We have to read two
> +	 * registers to get the sensor temperature, but we have to beware a
> +	 * conversion could occur between the readings. We could use the
> +	 * one-shot conversion register, but we don't want to do this (disables
> +	 * hardware monitoring). So the solution used here is to read the high
> +	 * byte once, then the low byte, then the high byte again. If the new
> +	 * high byte matches the old one, then we have a valid reading. Else we
> +	 * have to read the low byte again, and now we believe we have a correct
> +	 * reading.
> +	 */
> +	integer1 = i2c_smbus_read_byte_data(priv->client, STTS751_REG_TEMP_H);
> +	if (integer1 < 0) {
> +		dev_dbg(&priv->client->dev,
> +			"I2C read failed (temp H). ret: %x\n", integer1);
> +		return integer1;
> +	}
> +
> +	frac = i2c_smbus_read_byte_data(priv->client, STTS751_REG_TEMP_L);
> +	if (frac < 0) {
> +		dev_dbg(&priv->client->dev,
> +			"I2C read failed (temp L). ret: %x\n", frac);
> +		return frac;
> +	}
> +
> +	integer2 = i2c_smbus_read_byte_data(priv->client, STTS751_REG_TEMP_H);
> +	if (integer2 < 0) {
> +		dev_dbg(&priv->client->dev,
> +			"I2C 2nd read failed (temp H). ret: %x\n", integer2);
> +		return integer2;
> +	}
> +
> +	if (integer1 != integer2) {
> +		frac = i2c_smbus_read_byte_data(priv->client,
> +						STTS751_REG_TEMP_L);
> +		if (frac < 0) {
> +			dev_dbg(&priv->client->dev,
> +				"I2C 2nd read failed (temp L). ret: %x\n",
> +				frac);
> +			return frac;
> +		}
> +	}
> +
> +	priv->temp = stts751_to_deg((integer1 << 8) | frac);
> +	return 0;
> +}
> +
> +static int stts751_set_temp_reg16(struct stts751_priv *priv, int temp,
> +				  u8 hreg, u8 lreg)
> +{
> +	s32 hwval;
> +	int ret;
> +
> +	hwval = stts751_to_hw(temp);
> +
> +	ret = i2c_smbus_write_byte_data(priv->client, hreg, hwval >> 8);
> +	if (ret)
> +		return ret;
> +
> +	return i2c_smbus_write_byte_data(priv->client, lreg, hwval & 0xff);
> +}
> +
> +static int stts751_set_temp_reg8(struct stts751_priv *priv, int temp, u8 reg)
> +{
> +	s32 hwval;
> +
> +	hwval = stts751_to_hw(temp);
> +	return i2c_smbus_write_byte_data(priv->client, reg, hwval >> 8);
> +}
> +
> +static int stts751_read_reg16(struct stts751_priv *priv, int *temp,
> +			      u8 hreg, u8 lreg)
> +{
> +	int integer, frac;
> +
> +	integer = i2c_smbus_read_byte_data(priv->client, hreg);
> +	if (integer < 0)
> +		return integer;
> +
> +	frac = i2c_smbus_read_byte_data(priv->client, lreg);
> +	if (frac < 0)
> +		return frac;
> +
> +	*temp = stts751_to_deg((integer << 8) | frac);
> +
> +	return 0;
> +}
> +
> +static int stts751_read_reg8(struct stts751_priv *priv, int *temp, u8 reg)
> +{
> +	int integer;
> +
> +	integer = i2c_smbus_read_byte_data(priv->client, reg);
> +	if (integer < 0)
> +		return integer;
> +
> +	*temp = stts751_to_deg(integer << 8);
> +
> +	return 0;
> +}
> +
> +/*
> + * Update alert flags without waiting for cache to expire. We detects alerts
> + * immediately for the sake of the alert handler; we still need to deal with
> + * caching to workaround the fact that alarm flags int the status register,
> + * despite what the datasheet claims, gets always cleared on read.
> + */
> +static int stts751_update_alert(struct stts751_priv *priv)
> +{
> +	int ret;
> +	bool conv_done;
> +	int cache_time = msecs_to_jiffies(stts751_intervals[priv->interval]);
> +
> +	/*
> +	 * Add another 10% because if we run faster than the HW conversion
> +	 * rate we will end up in reporting incorrectly alarms.
> +	 */
> +	cache_time += cache_time / 10;
> +
> +	ret = i2c_smbus_read_byte_data(priv->client, STTS751_REG_STATUS);
> +	if (ret < 0)
> +		return ret;
> +
> +	dev_dbg(priv->dev, "status reg %x\n", ret);
> +	conv_done = ret & (STTS751_STATUS_TRIPH | STTS751_STATUS_TRIPL);
> +	/*
> +	 * Reset the cache if the cache time expired, or if we are sure
> +	 * we have valid data from a device conversion, or if we know
> +	 * our cache has been never written.
> +	 *
> +	 * Note that when the cache has been never written the point is
> +	 * to correctly initialize the timestamp, rather than clearing
> +	 * the cache values.
> +	 *
> +	 * Note that updating the cache timestamp when we get an alarm flag
> +	 * is required, otherwise we could incorrectly report alarms to be zero.
> +	 */
> +	if (time_after(jiffies,	priv->last_alert_update + cache_time) ||
> +	    conv_done || !priv->alert_valid) {
> +		priv->max_alert = false;
> +		priv->min_alert = false;
> +		priv->alert_valid = true;
> +		priv->last_alert_update = jiffies;
> +		dev_dbg(priv->dev, "invalidating alert cache\n");
> +	}
> +
> +	priv->max_alert |= !!(ret & STTS751_STATUS_TRIPH);
> +	priv->min_alert |= !!(ret & STTS751_STATUS_TRIPL);
> +	priv->therm_trip = !!(ret & STTS751_STATUS_TRIPT);
> +
> +	dev_dbg(priv->dev, "max_alert: %d, min_alert: %d, therm_trip: %d\n",
> +		priv->max_alert, priv->min_alert, priv->therm_trip);
> +
> +	return 0;
> +}
> +
> +static void stts751_alert(struct i2c_client *client,
> +			  enum i2c_alert_protocol type, unsigned int data)
> +{
> +	int ret;
> +	struct stts751_priv *priv = i2c_get_clientdata(client);
> +
> +	if (type != I2C_PROTOCOL_SMBUS_ALERT)
> +		return;
> +
> +	dev_dbg(&client->dev, "alert!");
> +
> +	mutex_lock(&priv->access_lock);
> +	ret = stts751_update_alert(priv);
> +	if (ret < 0) {
> +		/* default to worst case */
> +		priv->max_alert = true;
> +		priv->min_alert = true;
> +
> +		dev_warn(&priv->client->dev,
> +			 "Alert received, but can't communicate to the device. Triggering all alarms!");
> +	}
> +
> +	if (priv->max_alert) {
> +		dev_notice(&client->dev, "got alert for HIGH temperature");
> +
> +		/* unblock alert poll */
> +		sysfs_notify(&priv->dev->kobj, NULL, "temp1_max_alarm");
> +	}
> +
> +	if (priv->min_alert) {
> +		dev_notice(&client->dev, "got alert for LOW temperature");
> +
> +		/* unblock alert poll */
> +		sysfs_notify(&priv->dev->kobj, NULL, "temp1_min_alarm");
> +	}
> +
> +	if (priv->min_alert || priv->max_alert)
> +		kobject_uevent(&priv->dev->kobj, KOBJ_CHANGE);
> +
> +	mutex_unlock(&priv->access_lock);
> +}
> +
> +static int stts751_update(struct stts751_priv *priv)
> +{
> +	int ret = 0;
> +	int cache_time = msecs_to_jiffies(stts751_intervals[priv->interval]);
> +
> +	mutex_lock(&priv->access_lock);
> +	if (time_after(jiffies,	priv->last_update + cache_time) ||
> +	    !priv->data_valid) {
> +		ret = stts751_update_temp(priv);
> +		if (ret)
> +			goto exit;
> +
> +		ret = stts751_update_alert(priv);
> +		if (ret)
> +			goto exit;
> +		priv->data_valid = true;
> +		priv->last_update = jiffies;
> +	}
> +exit:
> +	mutex_unlock(&priv->access_lock);
> +
> +	return ret;
> +}
> +
> +static ssize_t show_max_alarm(struct device *dev, struct device_attribute *attr,
> +			      char *buf)
> +{
> +	int ret;
> +	struct stts751_priv *priv = dev_get_drvdata(dev);
> +
> +	ret = stts751_update(priv);
> +	if (ret < 0)
> +		return ret;
> +
> +	return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->max_alert);
> +}
> +
> +static ssize_t show_min_alarm(struct device *dev, struct device_attribute *attr,
> +			      char *buf)
> +{
> +	int ret;
> +	struct stts751_priv *priv = dev_get_drvdata(dev);
> +
> +	ret = stts751_update(priv);
> +	if (ret < 0)
> +		return ret;
> +
> +	return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->min_alert);
> +}
> +
> +static ssize_t show_input(struct device *dev, struct device_attribute *attr,
> +			  char *buf)
> +{
> +	int ret;
> +	struct stts751_priv *priv = dev_get_drvdata(dev);
> +
> +	ret = stts751_update(priv);
> +	if (ret < 0)
> +		return ret;
> +
> +	return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->temp);
> +}
> +
> +static ssize_t show_therm(struct device *dev, struct device_attribute *attr,
> +			  char *buf)
> +{
> +	struct stts751_priv *priv = dev_get_drvdata(dev);
> +
> +	return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->therm);
> +}
> +
> +static ssize_t set_therm(struct device *dev, struct device_attribute *attr,
> +			 const char *buf, size_t count)
> +{
> +	int ret;
> +	long temp;
> +	struct stts751_priv *priv = dev_get_drvdata(dev);
> +
> +	if (kstrtol(buf, 10, &temp) < 0)
> +		return -EINVAL;
> +
> +	/* HW works in range -64C to +127.937C */
> +	temp = clamp_val(temp, -64000, 127937);
> +	mutex_lock(&priv->access_lock);
> +	ret = stts751_set_temp_reg8(priv, temp, STTS751_REG_TLIM);
> +	if (ret)
> +		goto exit;
> +
> +	dev_dbg(dev, "setting therm %ld", temp);
> +
> +	/*
> +	 * hysteresis reg is relative to therm, so the HW does not need to be
> +	 * adjusted, we need to update our local copy only.
> +	 */
> +	priv->hyst = temp - (priv->therm - priv->hyst);
> +	priv->therm = temp;
> +
> +exit:
> +	mutex_unlock(&priv->access_lock);
> +	if (ret)
> +		return ret;
> +
> +	return count;
> +}
> +
> +static ssize_t show_hyst(struct device *dev, struct device_attribute *attr,
> +			 char *buf)
> +{
> +	struct stts751_priv *priv = dev_get_drvdata(dev);
> +
> +	return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->hyst);
> +}
> +
> +static ssize_t set_hyst(struct device *dev, struct device_attribute *attr,
> +			const char *buf, size_t count)
> +{
> +	int ret;
> +	long temp;
> +
> +	struct stts751_priv *priv = dev_get_drvdata(dev);
> +
> +	if (kstrtol(buf, 10, &temp) < 0)
> +		return -EINVAL;
> +
> +	mutex_lock(&priv->access_lock);
> +	/* HW works in range -64C to +127.937C */
> +	temp = clamp_val(temp, -64000, priv->therm);
> +	priv->hyst = temp;
> +	dev_dbg(priv->dev, "setting hyst %ld", temp);
> +	temp = priv->therm - temp;
> +	ret = stts751_set_temp_reg8(priv, temp, STTS751_REG_HYST);
> +	mutex_unlock(&priv->access_lock);
> +	if (ret)
> +		return ret;
> +
> +	return count;
> +}
> +
> +static ssize_t show_therm_trip(struct device *dev,
> +			       struct device_attribute *attr, char *buf)
> +{
> +	int ret;
> +	struct stts751_priv *priv = dev_get_drvdata(dev);
> +
> +	ret = stts751_update(priv);
> +	if (ret < 0)
> +		return ret;
> +
> +	return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->therm_trip);
> +}
> +
> +static ssize_t show_max(struct device *dev, struct device_attribute *attr,
> +			char *buf)
> +{
> +	struct stts751_priv *priv = dev_get_drvdata(dev);
> +
> +	return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->event_max);
> +}
> +
> +static ssize_t set_max(struct device *dev, struct device_attribute *attr,
> +		       const char *buf, size_t count)
> +{
> +	int ret;
> +	long temp;
> +	struct stts751_priv *priv = dev_get_drvdata(dev);
> +
> +	if (kstrtol(buf, 10, &temp) < 0)
> +		return -EINVAL;
> +
> +	mutex_lock(&priv->access_lock);
> +	/* HW works in range -64C to +127.937C */
> +	temp = clamp_val(temp, priv->event_min, 127937);
> +	ret = stts751_set_temp_reg16(priv, temp,
> +				     STTS751_REG_HLIM_H, STTS751_REG_HLIM_L);
> +	if (ret)
> +		goto exit;
> +
> +	dev_dbg(dev, "setting event max %ld", temp);
> +	priv->event_max = temp;
> +	ret = count;
> +exit:
> +	mutex_unlock(&priv->access_lock);
> +	return ret;
> +}
> +
> +static ssize_t show_min(struct device *dev, struct device_attribute *attr,
> +			char *buf)
> +{
> +	struct stts751_priv *priv = dev_get_drvdata(dev);
> +
> +	return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->event_min);
> +}
> +
> +static ssize_t set_min(struct device *dev, struct device_attribute *attr,
> +		       const char *buf, size_t count)
> +{
> +	int ret;
> +	long temp;
> +	struct stts751_priv *priv = dev_get_drvdata(dev);
> +
> +	if (kstrtol(buf, 10, &temp) < 0)
> +		return -EINVAL;
> +
> +	mutex_lock(&priv->access_lock);
> +	/* HW works in range -64C to +127.937C */
> +	temp = clamp_val(temp, -64000, priv->event_max);
> +	ret = stts751_set_temp_reg16(priv, temp,
> +				     STTS751_REG_LLIM_H, STTS751_REG_LLIM_L);
> +	if (ret)
> +		goto exit;
> +
> +	dev_dbg(dev, "setting event min %ld", temp);
> +	priv->event_min = temp;
> +	ret = count;
> +exit:
> +	mutex_unlock(&priv->access_lock);
> +	return ret;
> +}
> +
> +static ssize_t show_interval(struct device *dev, struct device_attribute *attr,
> +			     char *buf)
> +{
> +	struct stts751_priv *priv = dev_get_drvdata(dev);
> +
> +	return snprintf(buf, PAGE_SIZE - 1, "%d\n",
> +			stts751_intervals[priv->interval]);
> +}
> +
> +static ssize_t set_interval(struct device *dev, struct device_attribute *attr,
> +			    const char *buf, size_t count)
> +{
> +	unsigned long val;
> +	int idx;
> +	int ret = count;
> +	struct stts751_priv *priv = dev_get_drvdata(dev);
> +
> +	if (kstrtoul(buf, 10, &val) < 0)
> +		return -EINVAL;
> +
> +	idx = find_closest_descending(val, stts751_intervals,
> +				      ARRAY_SIZE(stts751_intervals));
> +
> +	dev_dbg(dev, "setting interval. req:%lu, idx: %d, val: %d", val, idx,
> +		stts751_intervals[idx]);
> +
> +	mutex_lock(&priv->access_lock);
> +	if (priv->interval == idx)
> +		goto exit;
> +
> +	/*
> +	 * In early development stages I've become suspicious about the chip
> +	 * starting to misbehave if I ever set, even briefly, an invalid
> +	 * configuration. While I'm not sure this is really needed, be
> +	 * conservative and set rate/resolution in such an order that avoids
> +	 * passing through an invalid configuration.
> +	 */
> +
> +	/* speed up: lower the resolution, then modify convrate */
> +	if (priv->interval < idx) {
> +		dev_dbg(priv->dev, "lower resolution, then modify convrate");
> +		priv->interval = idx;
> +		ret = stts751_adjust_resolution(priv);
> +		if (ret)
> +			goto exit;
> +	}
> +
> +	ret = i2c_smbus_write_byte_data(priv->client, STTS751_REG_RATE, idx);
> +	if (ret)
> +		goto exit;
> +	/* slow down: modify convrate, then raise resolution */
> +	if (priv->interval != idx) {
> +		dev_dbg(priv->dev, "modify convrate, then raise resolution");
> +		priv->interval = idx;
> +		ret = stts751_adjust_resolution(priv);
> +		if (ret)
> +			goto exit;
> +	}
> +	ret = count;
> +exit:
> +	mutex_unlock(&priv->access_lock);
> +
> +	return ret;
> +}
> +
> +static int stts751_detect(struct i2c_client *new_client,
> +			  struct i2c_board_info *info)
> +{
> +	struct i2c_adapter *adapter = new_client->adapter;
> +	const char *name;
> +	int tmp;
> +
> +	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
> +		return -ENODEV;
> +
> +	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_MAN_ID);
> +	if (tmp != ST_MAN_ID)
> +		return -ENODEV;
> +
> +	/* lower temperaure registers always have bits 0-3 set to zero */
> +	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_TEMP_L);
> +	if (tmp & 0xf)
> +		return -ENODEV;
> +
> +	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_HLIM_L);
> +	if (tmp & 0xf)
> +		return -ENODEV;
> +
> +	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_LLIM_L);
> +	if (tmp & 0xf)
> +		return -ENODEV;
> +
> +	/* smbus timeout register always have bits 0-7 set to zero */
> +	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_SMBUS_TO);
> +	if (tmp & 0x7f)
> +		return -ENODEV;
> +
> +	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_PROD_ID);
> +
> +	switch (tmp) {
> +	case STTS751_0_PROD_ID:
> +		name = "STTS751-0";
> +		break;
> +	case STTS751_1_PROD_ID:
> +		name = "STTS751-1";
> +		break;
> +	default:
> +		return -ENODEV;
> +	}
> +	dev_dbg(&new_client->dev, "Chip %s detected", name);
> +
> +	strlcpy(info->type, stts751_id[0].name, I2C_NAME_SIZE);
> +	return 0;
> +}
> +
> +static int stts751_read_chip_config(struct stts751_priv *priv)
> +{
> +	int ret;
> +	int tmp;
> +
> +	ret = i2c_smbus_read_byte_data(priv->client, STTS751_REG_CONF);
> +	if (ret < 0)
> +		return ret;
> +	priv->config = ret;
> +	priv->res = (ret & STTS751_CONF_RES_MASK) >> STTS751_CONF_RES_SHIFT;
> +
> +	ret = i2c_smbus_read_byte_data(priv->client, STTS751_REG_RATE);
> +	if (ret < 0)
> +		return ret;
> +	priv->interval = ret;
> +
> +	ret = stts751_read_reg16(priv, &priv->event_max,
> +				 STTS751_REG_HLIM_H, STTS751_REG_HLIM_L);
> +	if (ret)
> +		return ret;
> +
> +	ret = stts751_read_reg16(priv, &priv->event_min,
> +				 STTS751_REG_LLIM_H, STTS751_REG_LLIM_L);
> +	if (ret)
> +		return ret;
> +
> +	ret = stts751_read_reg8(priv, &priv->therm, STTS751_REG_TLIM);
> +	if (ret)
> +		return ret;
> +
> +	ret = stts751_read_reg8(priv, &tmp, STTS751_REG_HYST);
> +	if (ret)
> +		return ret;
> +	priv->hyst = priv->therm - tmp;
> +
> +	return 0;
> +}
> +
> +static SENSOR_DEVICE_ATTR(temp1_input, 0444, show_input, NULL, 0);
> +static SENSOR_DEVICE_ATTR(temp1_min, 0644, show_min, set_min, 0);
> +static SENSOR_DEVICE_ATTR(temp1_max, 0644, show_max, set_max, 0);
> +static SENSOR_DEVICE_ATTR(temp1_min_alarm, 0444, show_min_alarm, NULL, 0);
> +static SENSOR_DEVICE_ATTR(temp1_max_alarm, 0444, show_max_alarm, NULL, 0);
> +static SENSOR_DEVICE_ATTR(temp1_crit, 0644, show_therm,	set_therm, 0);
> +static SENSOR_DEVICE_ATTR(temp1_crit_hyst, 0644, show_hyst, set_hyst, 0);
> +static SENSOR_DEVICE_ATTR(temp1_crit_alarm, 0444, show_therm_trip, NULL, 0);
> +static SENSOR_DEVICE_ATTR(update_interval, 0644,
> +			  show_interval, set_interval, 0);
> +
> +static struct attribute *stts751_attrs[] = {
> +	&sensor_dev_attr_temp1_input.dev_attr.attr,
> +	&sensor_dev_attr_temp1_min.dev_attr.attr,
> +	&sensor_dev_attr_temp1_max.dev_attr.attr,
> +	&sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
> +	&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
> +	&sensor_dev_attr_temp1_crit.dev_attr.attr,
> +	&sensor_dev_attr_temp1_crit_hyst.dev_attr.attr,
> +	&sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
> +	&sensor_dev_attr_update_interval.dev_attr.attr,
> +	NULL
> +};
> +ATTRIBUTE_GROUPS(stts751);
> +
> +static int stts751_probe(struct i2c_client *client,
> +			 const struct i2c_device_id *id)
> +{
> +	struct stts751_priv *priv;
> +	int ret;
> +	bool smbus_nto;
> +	int rev_id;
> +
> +	priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->client = client;
> +	i2c_set_clientdata(client, priv);
> +	mutex_init(&priv->access_lock);
> +
> +	if (device_property_present(&client->dev,
> +				    "smbus-timeout-disable")) {
> +		smbus_nto = device_property_read_bool(&client->dev,
> +						      "smbus-timeout-disable");
> +
> +		ret = i2c_smbus_write_byte_data(priv->client,
> +						STTS751_REG_SMBUS_TO,
> +						smbus_nto ? 0 : 0x80);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	rev_id = i2c_smbus_read_byte_data(priv->client, STTS751_REG_REV_ID);
> +	if (rev_id < 0)
> +		return -ENODEV;
> +	if (rev_id != 0x1) {
> +		dev_dbg(&priv->client->dev, "Chip revision 0x%x is untested\n",
> +			rev_id);
> +	}
> +
> +	ret = stts751_read_chip_config(priv);
> +	if (ret)
> +		return ret;
> +
> +	priv->config &= ~(STTS751_CONF_STOP | STTS751_CONF_EVENT_DIS);
> +	ret = i2c_smbus_write_byte_data(priv->client,
> +					STTS751_REG_CONF, priv->config);
> +	if (ret)
> +		return ret;
> +
> +	priv->dev = devm_hwmon_device_register_with_groups(&client->dev,
> +							client->name, priv,
> +							stts751_groups);
> +	return PTR_ERR_OR_ZERO(priv->dev);
> +}
> +
> +MODULE_DEVICE_TABLE(i2c, stts751_id);
> +
> +static struct i2c_driver stts751_driver = {
> +	.class		= I2C_CLASS_HWMON,
> +	.driver = {
> +		.name	= DEVNAME,
> +	},
> +	.probe		= stts751_probe,
> +	.id_table	= stts751_id,
> +	.detect		= stts751_detect,
> +	.alert		= stts751_alert,
> +	.address_list	= normal_i2c,
> +};
> +
> +module_i2c_driver(stts751_driver);
> +
> +MODULE_AUTHOR("Andrea Merello <andrea.merello@gmail.com>");
> +MODULE_DESCRIPTION("STTS751 sensor driver");
> +MODULE_LICENSE("GPL");
>

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Andrea Merello Jan. 31, 2017, 7:11 a.m. UTC | #2
On Mon, Jan 30, 2017 at 3:24 PM, Guenter Roeck <linux@roeck-us.net> wrote:
> On 01/30/2017 01:40 AM, Andrea Merello wrote:
>>
>> This patch adds a HWMON driver for ST Microelectronics STTS751
>> temperature sensors.
>>
>
> Overall looks good. One thing I noticed, though: In the log function calls,
> you use a mix of priv->dev and &client->dev as log device. Also, you
> sometimes
> use &priv->client->dev even when a local client variable is available.
> I can fix up the latter (no need to resend for that), but please have a
> look at the overall use and either send a fixed up version or let me know
> if the log devices are all intentional as-is.

Hmm, you are right: there is a bit of mess here. It's not intentional indeed..

I gave a look to lm90.c and lm63.c; it seems no one uses the hwmon
device for this purpose. We can probably stick to &client->dev or
&priv->client->dev when a local client variable is not already
available.

Also, it looks like we can change some &priv->client->dev in
&client->dev in probe function when calling i2c read/write functions.

If you ACK, I'll fix and resend.

> Thanks,
> Guenter
>
>
>> Changes since V3:
>> - fix sysfs_notify() filename
>> - simplify error exit path in stts751_update_temp(): kill useless goto
>> - fix set function were racy due to lock incorrectly placed
>> - use msecs_to_jiffies instead of manual calculation
>> - fix jiffies and msecs were mixed up
>> - don't mark cache as good unless reads really succeded to fill up it
>> - when updating therm, hyst keeps relative value rather than abs value
>> - don't should in dev_dbg when chip is detected
>> - don't ever generate two uevents
>> - clarify clear-on-read behaviour of status reg alarm flags
>> - simplify mDEG to HW conversion function
>> - fix chip stops due to incorrect resolution configuration
>> - fix incorrectly reading negative numbers from HW
>>
>> Changes since V4:
>> - fix continuation lines (style, remove uncecessary, ..)
>> - shorten a unnecessary verbose dev_warn() message
>> - fix set_interval() exitpath didn't return error
>> - change uncecesary neg-logic
>> - change file symbolic permissions with octal
>> - move chip revision test in probe(), change dev_notice() in dev_dbg()
>> - use "return 0" on success (non functional change)
>> - add further checks in i2c detect function
>> - fix i2c detect function read wrong reg while checking for manufacturer
>> ID
>>
>> Thanks-to: LABBE Corentin [for suggestions]
>> Thanks-to: Guenter Roeck [for suggestion and discussions]
>> Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
>> Cc: LABBE Corentin <clabbe.montjoie@gmail.com>
>> Cc: Guenter Roeck <linux@roeck-us.net>
>> Cc: Jean Delvare <jdelvare@suse.com>
>> ---
>>  drivers/hwmon/Kconfig   |  10 +
>>  drivers/hwmon/Makefile  |   1 +
>>  drivers/hwmon/stts751.c | 819
>> ++++++++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 830 insertions(+)
>>  create mode 100644 drivers/hwmon/stts751.c
>>
>> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
>> index d1f82f2..8fdd241 100644
>> --- a/drivers/hwmon/Kconfig
>> +++ b/drivers/hwmon/Kconfig
>> @@ -1448,6 +1448,16 @@ config SENSORS_SCH5636
>>           This driver can also be built as a module.  If so, the module
>>           will be called sch5636.
>>
>> +config SENSORS_STTS751
>> +       tristate "ST Microelectronics STTS751"
>> +       depends on I2C
>> +       help
>> +         If you say yes here you get support for STTS751
>> +         temperature sensor chips.
>> +
>> +         This driver can also be built as a module.  If so, the module
>> +         will be called stts751.
>> +
>>  config SENSORS_SMM665
>>         tristate "Summit Microelectronics SMM665"
>>         depends on I2C
>> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
>> index 7476b22..1114130 100644
>> --- a/drivers/hwmon/Makefile
>> +++ b/drivers/hwmon/Makefile
>> @@ -147,6 +147,7 @@ obj-$(CONFIG_SENSORS_SMM665)        += smm665.o
>>  obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o
>>  obj-$(CONFIG_SENSORS_SMSC47M1) += smsc47m1.o
>>  obj-$(CONFIG_SENSORS_SMSC47M192)+= smsc47m192.o
>> +obj-$(CONFIG_SENSORS_STTS751)  += stts751.o
>>  obj-$(CONFIG_SENSORS_AMC6821)  += amc6821.o
>>  obj-$(CONFIG_SENSORS_TC74)     += tc74.o
>>  obj-$(CONFIG_SENSORS_THMC50)   += thmc50.o
>> diff --git a/drivers/hwmon/stts751.c b/drivers/hwmon/stts751.c
>> new file mode 100644
>> index 0000000..4154294
>> --- /dev/null
>> +++ b/drivers/hwmon/stts751.c
>> @@ -0,0 +1,819 @@
>> +/*
>> + * STTS751 sensor driver
>> + *
>> + * Copyright (C) 2016-2017 Istituto Italiano di Tecnologia - RBCS - EDL
>> + * Robotics, Brain and Cognitive Sciences department
>> + * Electronic Design Laboratory
>> + *
>> + * Written by Andrea Merello <andrea.merello@gmail.com>
>> + *
>> + * Based on  LM95241 driver and LM90 driver
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + */
>> +
>> +#include <linux/bitops.h>
>> +#include <linux/err.h>
>> +#include <linux/hwmon.h>
>> +#include <linux/hwmon-sysfs.h>
>> +#include <linux/i2c.h>
>> +#include <linux/init.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/jiffies.h>
>> +#include <linux/module.h>
>> +#include <linux/mutex.h>
>> +#include <linux/property.h>
>> +#include <linux/slab.h>
>> +#include <linux/sysfs.h>
>> +#include <linux/util_macros.h>
>> +
>> +#define DEVNAME "stts751"
>> +
>> +static const unsigned short normal_i2c[] = {
>> +       0x48, 0x49, 0x38, 0x39,  /* STTS751-0 */
>> +       0x4A, 0x4B, 0x3A, 0x3B,  /* STTS751-1 */
>> +       I2C_CLIENT_END };
>> +
>> +#define STTS751_REG_TEMP_H     0x00
>> +#define STTS751_REG_STATUS     0x01
>> +#define STTS751_STATUS_TRIPT   BIT(0)
>> +#define STTS751_STATUS_TRIPL   BIT(5)
>> +#define STTS751_STATUS_TRIPH   BIT(6)
>> +#define STTS751_REG_TEMP_L     0x02
>> +#define STTS751_REG_CONF       0x03
>> +#define STTS751_CONF_RES_MASK  0x0C
>> +#define STTS751_CONF_RES_SHIFT  2
>> +#define STTS751_CONF_EVENT_DIS  BIT(7)
>> +#define STTS751_CONF_STOP      BIT(6)
>> +#define STTS751_REG_RATE       0x04
>> +#define STTS751_REG_HLIM_H     0x05
>> +#define STTS751_REG_HLIM_L     0x06
>> +#define STTS751_REG_LLIM_H     0x07
>> +#define STTS751_REG_LLIM_L     0x08
>> +#define STTS751_REG_TLIM       0x20
>> +#define STTS751_REG_HYST       0x21
>> +#define STTS751_REG_SMBUS_TO   0x22
>> +
>> +#define STTS751_REG_PROD_ID    0xFD
>> +#define STTS751_REG_MAN_ID     0xFE
>> +#define STTS751_REG_REV_ID     0xFF
>> +
>> +#define STTS751_0_PROD_ID      0x00
>> +#define STTS751_1_PROD_ID      0x01
>> +#define ST_MAN_ID              0x53
>> +
>> +/*
>> + * Possible update intervals are (in mS):
>> + * 16000, 8000, 4000, 2000, 1000, 500, 250, 125, 62.5, 31.25
>> + * However we are not going to complicate things too much and we stick to
>> the
>> + * approx value in mS.
>> + */
>> +static const int stts751_intervals[] = {
>> +       16000, 8000, 4000, 2000, 1000, 500, 250, 125, 63, 31
>> +};
>> +
>> +static const struct i2c_device_id stts751_id[] = {
>> +       { "stts751", 0 },
>> +       { }
>> +};
>> +
>> +struct stts751_priv {
>> +       struct device *dev;
>> +       struct i2c_client *client;
>> +       struct mutex access_lock;
>> +       u8 interval;
>> +       int res;
>> +       int event_max, event_min;
>> +       int therm;
>> +       int hyst;
>> +       bool smbus_timeout;
>> +       int temp;
>> +       unsigned long last_update, last_alert_update;
>> +       u8 config;
>> +       bool min_alert, max_alert, therm_trip;
>> +       bool data_valid, alert_valid;
>> +};
>> +
>> +/*
>> + * These functions converts temperature from HW format to integer format
>> and
>> + * vice-vers. They are (mostly) taken from lm90 driver. Unit is in mC.
>> + */
>> +static int stts751_to_deg(s16 hw_val)
>> +{
>> +       return hw_val * 125 / 32;
>> +}
>> +
>> +static s32 stts751_to_hw(int val)
>> +{
>> +       return DIV_ROUND_CLOSEST(val, 125) * 32;
>> +}
>> +
>> +static int stts751_adjust_resolution(struct stts751_priv *priv)
>> +{
>> +       u8 res;
>> +
>> +       switch (priv->interval) {
>> +       case 9:
>> +               /* 10 bits */
>> +               res = 0;
>> +               break;
>> +       case 8:
>> +               /* 11 bits */
>> +               res = 1;
>> +               break;
>> +       default:
>> +               /* 12 bits */
>> +               res = 3;
>> +               break;
>> +       }
>> +
>> +       if (priv->res == res)
>> +               return 0;
>> +
>> +       priv->config &= ~STTS751_CONF_RES_MASK;
>> +       priv->config |= res << STTS751_CONF_RES_SHIFT;
>> +       dev_dbg(priv->dev, "setting res %d. config %x", res,
>> priv->config);
>> +       priv->res = res;
>> +
>> +       return i2c_smbus_write_byte_data(priv->client,
>> +                               STTS751_REG_CONF, priv->config);
>> +}
>> +
>> +static int stts751_update_temp(struct stts751_priv *priv)
>> +{
>> +       s32 integer1, integer2, frac;
>> +
>> +       /*
>> +        * There is a trick here, like in the lm90 driver. We have to read
>> two
>> +        * registers to get the sensor temperature, but we have to beware
>> a
>> +        * conversion could occur between the readings. We could use the
>> +        * one-shot conversion register, but we don't want to do this
>> (disables
>> +        * hardware monitoring). So the solution used here is to read the
>> high
>> +        * byte once, then the low byte, then the high byte again. If the
>> new
>> +        * high byte matches the old one, then we have a valid reading.
>> Else we
>> +        * have to read the low byte again, and now we believe we have a
>> correct
>> +        * reading.
>> +        */
>> +       integer1 = i2c_smbus_read_byte_data(priv->client,
>> STTS751_REG_TEMP_H);
>> +       if (integer1 < 0) {
>> +               dev_dbg(&priv->client->dev,
>> +                       "I2C read failed (temp H). ret: %x\n", integer1);
>> +               return integer1;
>> +       }
>> +
>> +       frac = i2c_smbus_read_byte_data(priv->client, STTS751_REG_TEMP_L);
>> +       if (frac < 0) {
>> +               dev_dbg(&priv->client->dev,
>> +                       "I2C read failed (temp L). ret: %x\n", frac);
>> +               return frac;
>> +       }
>> +
>> +       integer2 = i2c_smbus_read_byte_data(priv->client,
>> STTS751_REG_TEMP_H);
>> +       if (integer2 < 0) {
>> +               dev_dbg(&priv->client->dev,
>> +                       "I2C 2nd read failed (temp H). ret: %x\n",
>> integer2);
>> +               return integer2;
>> +       }
>> +
>> +       if (integer1 != integer2) {
>> +               frac = i2c_smbus_read_byte_data(priv->client,
>> +                                               STTS751_REG_TEMP_L);
>> +               if (frac < 0) {
>> +                       dev_dbg(&priv->client->dev,
>> +                               "I2C 2nd read failed (temp L). ret: %x\n",
>> +                               frac);
>> +                       return frac;
>> +               }
>> +       }
>> +
>> +       priv->temp = stts751_to_deg((integer1 << 8) | frac);
>> +       return 0;
>> +}
>> +
>> +static int stts751_set_temp_reg16(struct stts751_priv *priv, int temp,
>> +                                 u8 hreg, u8 lreg)
>> +{
>> +       s32 hwval;
>> +       int ret;
>> +
>> +       hwval = stts751_to_hw(temp);
>> +
>> +       ret = i2c_smbus_write_byte_data(priv->client, hreg, hwval >> 8);
>> +       if (ret)
>> +               return ret;
>> +
>> +       return i2c_smbus_write_byte_data(priv->client, lreg, hwval &
>> 0xff);
>> +}
>> +
>> +static int stts751_set_temp_reg8(struct stts751_priv *priv, int temp, u8
>> reg)
>> +{
>> +       s32 hwval;
>> +
>> +       hwval = stts751_to_hw(temp);
>> +       return i2c_smbus_write_byte_data(priv->client, reg, hwval >> 8);
>> +}
>> +
>> +static int stts751_read_reg16(struct stts751_priv *priv, int *temp,
>> +                             u8 hreg, u8 lreg)
>> +{
>> +       int integer, frac;
>> +
>> +       integer = i2c_smbus_read_byte_data(priv->client, hreg);
>> +       if (integer < 0)
>> +               return integer;
>> +
>> +       frac = i2c_smbus_read_byte_data(priv->client, lreg);
>> +       if (frac < 0)
>> +               return frac;
>> +
>> +       *temp = stts751_to_deg((integer << 8) | frac);
>> +
>> +       return 0;
>> +}
>> +
>> +static int stts751_read_reg8(struct stts751_priv *priv, int *temp, u8
>> reg)
>> +{
>> +       int integer;
>> +
>> +       integer = i2c_smbus_read_byte_data(priv->client, reg);
>> +       if (integer < 0)
>> +               return integer;
>> +
>> +       *temp = stts751_to_deg(integer << 8);
>> +
>> +       return 0;
>> +}
>> +
>> +/*
>> + * Update alert flags without waiting for cache to expire. We detects
>> alerts
>> + * immediately for the sake of the alert handler; we still need to deal
>> with
>> + * caching to workaround the fact that alarm flags int the status
>> register,
>> + * despite what the datasheet claims, gets always cleared on read.
>> + */
>> +static int stts751_update_alert(struct stts751_priv *priv)
>> +{
>> +       int ret;
>> +       bool conv_done;
>> +       int cache_time =
>> msecs_to_jiffies(stts751_intervals[priv->interval]);
>> +
>> +       /*
>> +        * Add another 10% because if we run faster than the HW conversion
>> +        * rate we will end up in reporting incorrectly alarms.
>> +        */
>> +       cache_time += cache_time / 10;
>> +
>> +       ret = i2c_smbus_read_byte_data(priv->client, STTS751_REG_STATUS);
>> +       if (ret < 0)
>> +               return ret;
>> +
>> +       dev_dbg(priv->dev, "status reg %x\n", ret);
>> +       conv_done = ret & (STTS751_STATUS_TRIPH | STTS751_STATUS_TRIPL);
>> +       /*
>> +        * Reset the cache if the cache time expired, or if we are sure
>> +        * we have valid data from a device conversion, or if we know
>> +        * our cache has been never written.
>> +        *
>> +        * Note that when the cache has been never written the point is
>> +        * to correctly initialize the timestamp, rather than clearing
>> +        * the cache values.
>> +        *
>> +        * Note that updating the cache timestamp when we get an alarm
>> flag
>> +        * is required, otherwise we could incorrectly report alarms to be
>> zero.
>> +        */
>> +       if (time_after(jiffies, priv->last_alert_update + cache_time) ||
>> +           conv_done || !priv->alert_valid) {
>> +               priv->max_alert = false;
>> +               priv->min_alert = false;
>> +               priv->alert_valid = true;
>> +               priv->last_alert_update = jiffies;
>> +               dev_dbg(priv->dev, "invalidating alert cache\n");
>> +       }
>> +
>> +       priv->max_alert |= !!(ret & STTS751_STATUS_TRIPH);
>> +       priv->min_alert |= !!(ret & STTS751_STATUS_TRIPL);
>> +       priv->therm_trip = !!(ret & STTS751_STATUS_TRIPT);
>> +
>> +       dev_dbg(priv->dev, "max_alert: %d, min_alert: %d, therm_trip:
>> %d\n",
>> +               priv->max_alert, priv->min_alert, priv->therm_trip);
>> +
>> +       return 0;
>> +}
>> +
>> +static void stts751_alert(struct i2c_client *client,
>> +                         enum i2c_alert_protocol type, unsigned int data)
>> +{
>> +       int ret;
>> +       struct stts751_priv *priv = i2c_get_clientdata(client);
>> +
>> +       if (type != I2C_PROTOCOL_SMBUS_ALERT)
>> +               return;
>> +
>> +       dev_dbg(&client->dev, "alert!");
>> +
>> +       mutex_lock(&priv->access_lock);
>> +       ret = stts751_update_alert(priv);
>> +       if (ret < 0) {
>> +               /* default to worst case */
>> +               priv->max_alert = true;
>> +               priv->min_alert = true;
>> +
>> +               dev_warn(&priv->client->dev,
>> +                        "Alert received, but can't communicate to the
>> device. Triggering all alarms!");
>> +       }
>> +
>> +       if (priv->max_alert) {
>> +               dev_notice(&client->dev, "got alert for HIGH
>> temperature");
>> +
>> +               /* unblock alert poll */
>> +               sysfs_notify(&priv->dev->kobj, NULL, "temp1_max_alarm");
>> +       }
>> +
>> +       if (priv->min_alert) {
>> +               dev_notice(&client->dev, "got alert for LOW temperature");
>> +
>> +               /* unblock alert poll */
>> +               sysfs_notify(&priv->dev->kobj, NULL, "temp1_min_alarm");
>> +       }
>> +
>> +       if (priv->min_alert || priv->max_alert)
>> +               kobject_uevent(&priv->dev->kobj, KOBJ_CHANGE);
>> +
>> +       mutex_unlock(&priv->access_lock);
>> +}
>> +
>> +static int stts751_update(struct stts751_priv *priv)
>> +{
>> +       int ret = 0;
>> +       int cache_time =
>> msecs_to_jiffies(stts751_intervals[priv->interval]);
>> +
>> +       mutex_lock(&priv->access_lock);
>> +       if (time_after(jiffies, priv->last_update + cache_time) ||
>> +           !priv->data_valid) {
>> +               ret = stts751_update_temp(priv);
>> +               if (ret)
>> +                       goto exit;
>> +
>> +               ret = stts751_update_alert(priv);
>> +               if (ret)
>> +                       goto exit;
>> +               priv->data_valid = true;
>> +               priv->last_update = jiffies;
>> +       }
>> +exit:
>> +       mutex_unlock(&priv->access_lock);
>> +
>> +       return ret;
>> +}
>> +
>> +static ssize_t show_max_alarm(struct device *dev, struct device_attribute
>> *attr,
>> +                             char *buf)
>> +{
>> +       int ret;
>> +       struct stts751_priv *priv = dev_get_drvdata(dev);
>> +
>> +       ret = stts751_update(priv);
>> +       if (ret < 0)
>> +               return ret;
>> +
>> +       return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->max_alert);
>> +}
>> +
>> +static ssize_t show_min_alarm(struct device *dev, struct device_attribute
>> *attr,
>> +                             char *buf)
>> +{
>> +       int ret;
>> +       struct stts751_priv *priv = dev_get_drvdata(dev);
>> +
>> +       ret = stts751_update(priv);
>> +       if (ret < 0)
>> +               return ret;
>> +
>> +       return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->min_alert);
>> +}
>> +
>> +static ssize_t show_input(struct device *dev, struct device_attribute
>> *attr,
>> +                         char *buf)
>> +{
>> +       int ret;
>> +       struct stts751_priv *priv = dev_get_drvdata(dev);
>> +
>> +       ret = stts751_update(priv);
>> +       if (ret < 0)
>> +               return ret;
>> +
>> +       return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->temp);
>> +}
>> +
>> +static ssize_t show_therm(struct device *dev, struct device_attribute
>> *attr,
>> +                         char *buf)
>> +{
>> +       struct stts751_priv *priv = dev_get_drvdata(dev);
>> +
>> +       return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->therm);
>> +}
>> +
>> +static ssize_t set_therm(struct device *dev, struct device_attribute
>> *attr,
>> +                        const char *buf, size_t count)
>> +{
>> +       int ret;
>> +       long temp;
>> +       struct stts751_priv *priv = dev_get_drvdata(dev);
>> +
>> +       if (kstrtol(buf, 10, &temp) < 0)
>> +               return -EINVAL;
>> +
>> +       /* HW works in range -64C to +127.937C */
>> +       temp = clamp_val(temp, -64000, 127937);
>> +       mutex_lock(&priv->access_lock);
>> +       ret = stts751_set_temp_reg8(priv, temp, STTS751_REG_TLIM);
>> +       if (ret)
>> +               goto exit;
>> +
>> +       dev_dbg(dev, "setting therm %ld", temp);
>> +
>> +       /*
>> +        * hysteresis reg is relative to therm, so the HW does not need to
>> be
>> +        * adjusted, we need to update our local copy only.
>> +        */
>> +       priv->hyst = temp - (priv->therm - priv->hyst);
>> +       priv->therm = temp;
>> +
>> +exit:
>> +       mutex_unlock(&priv->access_lock);
>> +       if (ret)
>> +               return ret;
>> +
>> +       return count;
>> +}
>> +
>> +static ssize_t show_hyst(struct device *dev, struct device_attribute
>> *attr,
>> +                        char *buf)
>> +{
>> +       struct stts751_priv *priv = dev_get_drvdata(dev);
>> +
>> +       return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->hyst);
>> +}
>> +
>> +static ssize_t set_hyst(struct device *dev, struct device_attribute
>> *attr,
>> +                       const char *buf, size_t count)
>> +{
>> +       int ret;
>> +       long temp;
>> +
>> +       struct stts751_priv *priv = dev_get_drvdata(dev);
>> +
>> +       if (kstrtol(buf, 10, &temp) < 0)
>> +               return -EINVAL;
>> +
>> +       mutex_lock(&priv->access_lock);
>> +       /* HW works in range -64C to +127.937C */
>> +       temp = clamp_val(temp, -64000, priv->therm);
>> +       priv->hyst = temp;
>> +       dev_dbg(priv->dev, "setting hyst %ld", temp);
>> +       temp = priv->therm - temp;
>> +       ret = stts751_set_temp_reg8(priv, temp, STTS751_REG_HYST);
>> +       mutex_unlock(&priv->access_lock);
>> +       if (ret)
>> +               return ret;
>> +
>> +       return count;
>> +}
>> +
>> +static ssize_t show_therm_trip(struct device *dev,
>> +                              struct device_attribute *attr, char *buf)
>> +{
>> +       int ret;
>> +       struct stts751_priv *priv = dev_get_drvdata(dev);
>> +
>> +       ret = stts751_update(priv);
>> +       if (ret < 0)
>> +               return ret;
>> +
>> +       return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->therm_trip);
>> +}
>> +
>> +static ssize_t show_max(struct device *dev, struct device_attribute
>> *attr,
>> +                       char *buf)
>> +{
>> +       struct stts751_priv *priv = dev_get_drvdata(dev);
>> +
>> +       return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->event_max);
>> +}
>> +
>> +static ssize_t set_max(struct device *dev, struct device_attribute *attr,
>> +                      const char *buf, size_t count)
>> +{
>> +       int ret;
>> +       long temp;
>> +       struct stts751_priv *priv = dev_get_drvdata(dev);
>> +
>> +       if (kstrtol(buf, 10, &temp) < 0)
>> +               return -EINVAL;
>> +
>> +       mutex_lock(&priv->access_lock);
>> +       /* HW works in range -64C to +127.937C */
>> +       temp = clamp_val(temp, priv->event_min, 127937);
>> +       ret = stts751_set_temp_reg16(priv, temp,
>> +                                    STTS751_REG_HLIM_H,
>> STTS751_REG_HLIM_L);
>> +       if (ret)
>> +               goto exit;
>> +
>> +       dev_dbg(dev, "setting event max %ld", temp);
>> +       priv->event_max = temp;
>> +       ret = count;
>> +exit:
>> +       mutex_unlock(&priv->access_lock);
>> +       return ret;
>> +}
>> +
>> +static ssize_t show_min(struct device *dev, struct device_attribute
>> *attr,
>> +                       char *buf)
>> +{
>> +       struct stts751_priv *priv = dev_get_drvdata(dev);
>> +
>> +       return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->event_min);
>> +}
>> +
>> +static ssize_t set_min(struct device *dev, struct device_attribute *attr,
>> +                      const char *buf, size_t count)
>> +{
>> +       int ret;
>> +       long temp;
>> +       struct stts751_priv *priv = dev_get_drvdata(dev);
>> +
>> +       if (kstrtol(buf, 10, &temp) < 0)
>> +               return -EINVAL;
>> +
>> +       mutex_lock(&priv->access_lock);
>> +       /* HW works in range -64C to +127.937C */
>> +       temp = clamp_val(temp, -64000, priv->event_max);
>> +       ret = stts751_set_temp_reg16(priv, temp,
>> +                                    STTS751_REG_LLIM_H,
>> STTS751_REG_LLIM_L);
>> +       if (ret)
>> +               goto exit;
>> +
>> +       dev_dbg(dev, "setting event min %ld", temp);
>> +       priv->event_min = temp;
>> +       ret = count;
>> +exit:
>> +       mutex_unlock(&priv->access_lock);
>> +       return ret;
>> +}
>> +
>> +static ssize_t show_interval(struct device *dev, struct device_attribute
>> *attr,
>> +                            char *buf)
>> +{
>> +       struct stts751_priv *priv = dev_get_drvdata(dev);
>> +
>> +       return snprintf(buf, PAGE_SIZE - 1, "%d\n",
>> +                       stts751_intervals[priv->interval]);
>> +}
>> +
>> +static ssize_t set_interval(struct device *dev, struct device_attribute
>> *attr,
>> +                           const char *buf, size_t count)
>> +{
>> +       unsigned long val;
>> +       int idx;
>> +       int ret = count;
>> +       struct stts751_priv *priv = dev_get_drvdata(dev);
>> +
>> +       if (kstrtoul(buf, 10, &val) < 0)
>> +               return -EINVAL;
>> +
>> +       idx = find_closest_descending(val, stts751_intervals,
>> +                                     ARRAY_SIZE(stts751_intervals));
>> +
>> +       dev_dbg(dev, "setting interval. req:%lu, idx: %d, val: %d", val,
>> idx,
>> +               stts751_intervals[idx]);
>> +
>> +       mutex_lock(&priv->access_lock);
>> +       if (priv->interval == idx)
>> +               goto exit;
>> +
>> +       /*
>> +        * In early development stages I've become suspicious about the
>> chip
>> +        * starting to misbehave if I ever set, even briefly, an invalid
>> +        * configuration. While I'm not sure this is really needed, be
>> +        * conservative and set rate/resolution in such an order that
>> avoids
>> +        * passing through an invalid configuration.
>> +        */
>> +
>> +       /* speed up: lower the resolution, then modify convrate */
>> +       if (priv->interval < idx) {
>> +               dev_dbg(priv->dev, "lower resolution, then modify
>> convrate");
>> +               priv->interval = idx;
>> +               ret = stts751_adjust_resolution(priv);
>> +               if (ret)
>> +                       goto exit;
>> +       }
>> +
>> +       ret = i2c_smbus_write_byte_data(priv->client, STTS751_REG_RATE,
>> idx);
>> +       if (ret)
>> +               goto exit;
>> +       /* slow down: modify convrate, then raise resolution */
>> +       if (priv->interval != idx) {
>> +               dev_dbg(priv->dev, "modify convrate, then raise
>> resolution");
>> +               priv->interval = idx;
>> +               ret = stts751_adjust_resolution(priv);
>> +               if (ret)
>> +                       goto exit;
>> +       }
>> +       ret = count;
>> +exit:
>> +       mutex_unlock(&priv->access_lock);
>> +
>> +       return ret;
>> +}
>> +
>> +static int stts751_detect(struct i2c_client *new_client,
>> +                         struct i2c_board_info *info)
>> +{
>> +       struct i2c_adapter *adapter = new_client->adapter;
>> +       const char *name;
>> +       int tmp;
>> +
>> +       if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
>> +               return -ENODEV;
>> +
>> +       tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_MAN_ID);
>> +       if (tmp != ST_MAN_ID)
>> +               return -ENODEV;
>> +
>> +       /* lower temperaure registers always have bits 0-3 set to zero */
>> +       tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_TEMP_L);
>> +       if (tmp & 0xf)
>> +               return -ENODEV;
>> +
>> +       tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_HLIM_L);
>> +       if (tmp & 0xf)
>> +               return -ENODEV;
>> +
>> +       tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_LLIM_L);
>> +       if (tmp & 0xf)
>> +               return -ENODEV;
>> +
>> +       /* smbus timeout register always have bits 0-7 set to zero */
>> +       tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_SMBUS_TO);
>> +       if (tmp & 0x7f)
>> +               return -ENODEV;
>> +
>> +       tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_PROD_ID);
>> +
>> +       switch (tmp) {
>> +       case STTS751_0_PROD_ID:
>> +               name = "STTS751-0";
>> +               break;
>> +       case STTS751_1_PROD_ID:
>> +               name = "STTS751-1";
>> +               break;
>> +       default:
>> +               return -ENODEV;
>> +       }
>> +       dev_dbg(&new_client->dev, "Chip %s detected", name);
>> +
>> +       strlcpy(info->type, stts751_id[0].name, I2C_NAME_SIZE);
>> +       return 0;
>> +}
>> +
>> +static int stts751_read_chip_config(struct stts751_priv *priv)
>> +{
>> +       int ret;
>> +       int tmp;
>> +
>> +       ret = i2c_smbus_read_byte_data(priv->client, STTS751_REG_CONF);
>> +       if (ret < 0)
>> +               return ret;
>> +       priv->config = ret;
>> +       priv->res = (ret & STTS751_CONF_RES_MASK) >>
>> STTS751_CONF_RES_SHIFT;
>> +
>> +       ret = i2c_smbus_read_byte_data(priv->client, STTS751_REG_RATE);
>> +       if (ret < 0)
>> +               return ret;
>> +       priv->interval = ret;
>> +
>> +       ret = stts751_read_reg16(priv, &priv->event_max,
>> +                                STTS751_REG_HLIM_H, STTS751_REG_HLIM_L);
>> +       if (ret)
>> +               return ret;
>> +
>> +       ret = stts751_read_reg16(priv, &priv->event_min,
>> +                                STTS751_REG_LLIM_H, STTS751_REG_LLIM_L);
>> +       if (ret)
>> +               return ret;
>> +
>> +       ret = stts751_read_reg8(priv, &priv->therm, STTS751_REG_TLIM);
>> +       if (ret)
>> +               return ret;
>> +
>> +       ret = stts751_read_reg8(priv, &tmp, STTS751_REG_HYST);
>> +       if (ret)
>> +               return ret;
>> +       priv->hyst = priv->therm - tmp;
>> +
>> +       return 0;
>> +}
>> +
>> +static SENSOR_DEVICE_ATTR(temp1_input, 0444, show_input, NULL, 0);
>> +static SENSOR_DEVICE_ATTR(temp1_min, 0644, show_min, set_min, 0);
>> +static SENSOR_DEVICE_ATTR(temp1_max, 0644, show_max, set_max, 0);
>> +static SENSOR_DEVICE_ATTR(temp1_min_alarm, 0444, show_min_alarm, NULL,
>> 0);
>> +static SENSOR_DEVICE_ATTR(temp1_max_alarm, 0444, show_max_alarm, NULL,
>> 0);
>> +static SENSOR_DEVICE_ATTR(temp1_crit, 0644, show_therm,        set_therm,
>> 0);
>> +static SENSOR_DEVICE_ATTR(temp1_crit_hyst, 0644, show_hyst, set_hyst, 0);
>> +static SENSOR_DEVICE_ATTR(temp1_crit_alarm, 0444, show_therm_trip, NULL,
>> 0);
>> +static SENSOR_DEVICE_ATTR(update_interval, 0644,
>> +                         show_interval, set_interval, 0);
>> +
>> +static struct attribute *stts751_attrs[] = {
>> +       &sensor_dev_attr_temp1_input.dev_attr.attr,
>> +       &sensor_dev_attr_temp1_min.dev_attr.attr,
>> +       &sensor_dev_attr_temp1_max.dev_attr.attr,
>> +       &sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
>> +       &sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
>> +       &sensor_dev_attr_temp1_crit.dev_attr.attr,
>> +       &sensor_dev_attr_temp1_crit_hyst.dev_attr.attr,
>> +       &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
>> +       &sensor_dev_attr_update_interval.dev_attr.attr,
>> +       NULL
>> +};
>> +ATTRIBUTE_GROUPS(stts751);
>> +
>> +static int stts751_probe(struct i2c_client *client,
>> +                        const struct i2c_device_id *id)
>> +{
>> +       struct stts751_priv *priv;
>> +       int ret;
>> +       bool smbus_nto;
>> +       int rev_id;
>> +
>> +       priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
>> +       if (!priv)
>> +               return -ENOMEM;
>> +
>> +       priv->client = client;
>> +       i2c_set_clientdata(client, priv);
>> +       mutex_init(&priv->access_lock);
>> +
>> +       if (device_property_present(&client->dev,
>> +                                   "smbus-timeout-disable")) {
>> +               smbus_nto = device_property_read_bool(&client->dev,
>> +
>> "smbus-timeout-disable");
>> +
>> +               ret = i2c_smbus_write_byte_data(priv->client,
>> +                                               STTS751_REG_SMBUS_TO,
>> +                                               smbus_nto ? 0 : 0x80);
>> +               if (ret)
>> +                       return ret;
>> +       }
>> +
>> +       rev_id = i2c_smbus_read_byte_data(priv->client,
>> STTS751_REG_REV_ID);
>> +       if (rev_id < 0)
>> +               return -ENODEV;
>> +       if (rev_id != 0x1) {
>> +               dev_dbg(&priv->client->dev, "Chip revision 0x%x is
>> untested\n",
>> +                       rev_id);
>> +       }
>> +
>> +       ret = stts751_read_chip_config(priv);
>> +       if (ret)
>> +               return ret;
>> +
>> +       priv->config &= ~(STTS751_CONF_STOP | STTS751_CONF_EVENT_DIS);
>> +       ret = i2c_smbus_write_byte_data(priv->client,
>> +                                       STTS751_REG_CONF, priv->config);
>> +       if (ret)
>> +               return ret;
>> +
>> +       priv->dev = devm_hwmon_device_register_with_groups(&client->dev,
>> +                                                       client->name,
>> priv,
>> +                                                       stts751_groups);
>> +       return PTR_ERR_OR_ZERO(priv->dev);
>> +}
>> +
>> +MODULE_DEVICE_TABLE(i2c, stts751_id);
>> +
>> +static struct i2c_driver stts751_driver = {
>> +       .class          = I2C_CLASS_HWMON,
>> +       .driver = {
>> +               .name   = DEVNAME,
>> +       },
>> +       .probe          = stts751_probe,
>> +       .id_table       = stts751_id,
>> +       .detect         = stts751_detect,
>> +       .alert          = stts751_alert,
>> +       .address_list   = normal_i2c,
>> +};
>> +
>> +module_i2c_driver(stts751_driver);
>> +
>> +MODULE_AUTHOR("Andrea Merello <andrea.merello@gmail.com>");
>> +MODULE_DESCRIPTION("STTS751 sensor driver");
>> +MODULE_LICENSE("GPL");
>>
>
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Guenter Roeck Jan. 31, 2017, 11:47 a.m. UTC | #3
On 01/30/2017 11:11 PM, Andrea Merello wrote:
> On Mon, Jan 30, 2017 at 3:24 PM, Guenter Roeck <linux@roeck-us.net> wrote:
>> On 01/30/2017 01:40 AM, Andrea Merello wrote:
>>>
>>> This patch adds a HWMON driver for ST Microelectronics STTS751
>>> temperature sensors.
>>>
>>
>> Overall looks good. One thing I noticed, though: In the log function calls,
>> you use a mix of priv->dev and &client->dev as log device. Also, you
>> sometimes
>> use &priv->client->dev even when a local client variable is available.
>> I can fix up the latter (no need to resend for that), but please have a
>> look at the overall use and either send a fixed up version or let me know
>> if the log devices are all intentional as-is.
>
> Hmm, you are right: there is a bit of mess here. It's not intentional indeed..
>
> I gave a look to lm90.c and lm63.c; it seems no one uses the hwmon
> device for this purpose. We can probably stick to &client->dev or
> &priv->client->dev when a local client variable is not already
> available.

It is really your call as the driver's author to make if you want to use
the hwmon device or &client->dev.
>
> Also, it looks like we can change some &priv->client->dev in
> &client->dev in probe function when calling i2c read/write functions.
>
> If you ACK, I'll fix and resend.
>
SGTM.

Thanks,
Guenter

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Andrea Merello Feb. 1, 2017, 7:31 a.m. UTC | #4
On Tue, Jan 31, 2017 at 12:47 PM, Guenter Roeck <linux@roeck-us.net> wrote:
> On 01/30/2017 11:11 PM, Andrea Merello wrote:
>>
>> On Mon, Jan 30, 2017 at 3:24 PM, Guenter Roeck <linux@roeck-us.net> wrote:
>>>
>>> On 01/30/2017 01:40 AM, Andrea Merello wrote:
>>>>
>>>>
>>>> This patch adds a HWMON driver for ST Microelectronics STTS751
>>>> temperature sensors.
>>>>
>>>
>>> Overall looks good. One thing I noticed, though: In the log function
>>> calls,
>>> you use a mix of priv->dev and &client->dev as log device. Also, you
>>> sometimes
>>> use &priv->client->dev even when a local client variable is available.
>>> I can fix up the latter (no need to resend for that), but please have a
>>> look at the overall use and either send a fixed up version or let me know
>>> if the log devices are all intentional as-is.
>>
>>
>> Hmm, you are right: there is a bit of mess here. It's not intentional
>> indeed..
>>
>> I gave a look to lm90.c and lm63.c; it seems no one uses the hwmon
>> device for this purpose. We can probably stick to &client->dev or
>> &priv->client->dev when a local client variable is not already
>> available.
>
>
> It is really your call as the driver's author to make if you want to use
> the hwmon device or &client->dev.

I've decided to stick with &client->dev for all dev_dbg(), while I
would use the hwmon device for dev_notice() and dev_warn(), that are
supposed to be eventually read by the user.

However, while keeping an eye on the log messages I've realized that
if the temperature remains out-of-limit for a lot of time, especially
if the conversion rate is set fast, we tend to spam the log with alert
messages.. I learned that you are usually concerned by noisy drivers,
so I guess you might want to mitigate this..

I could use dev_notice_once(), but it seems inappropriate here, or I
can silence the message at least until one reads the chip. Lm90 does
even disable the alarm until that happen, but it has only one alarm;
here we have two, so it seems not correct here.

Any suggestion?


>>
>>
>> Also, it looks like we can change some &priv->client->dev in
>> &client->dev in probe function when calling i2c read/write functions.
>>
>> If you ACK, I'll fix and resend.
>>
> SGTM.
>
> Thanks,
> Guenter
>
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Guenter Roeck Feb. 1, 2017, 2:11 p.m. UTC | #5
On 01/31/2017 11:31 PM, Andrea Merello wrote:
> On Tue, Jan 31, 2017 at 12:47 PM, Guenter Roeck <linux@roeck-us.net> wrote:
>> On 01/30/2017 11:11 PM, Andrea Merello wrote:
>>>
>>> On Mon, Jan 30, 2017 at 3:24 PM, Guenter Roeck <linux@roeck-us.net> wrote:
>>>>
>>>> On 01/30/2017 01:40 AM, Andrea Merello wrote:
>>>>>
>>>>>
>>>>> This patch adds a HWMON driver for ST Microelectronics STTS751
>>>>> temperature sensors.
>>>>>
>>>>
>>>> Overall looks good. One thing I noticed, though: In the log function
>>>> calls,
>>>> you use a mix of priv->dev and &client->dev as log device. Also, you
>>>> sometimes
>>>> use &priv->client->dev even when a local client variable is available.
>>>> I can fix up the latter (no need to resend for that), but please have a
>>>> look at the overall use and either send a fixed up version or let me know
>>>> if the log devices are all intentional as-is.
>>>
>>>
>>> Hmm, you are right: there is a bit of mess here. It's not intentional
>>> indeed..
>>>
>>> I gave a look to lm90.c and lm63.c; it seems no one uses the hwmon
>>> device for this purpose. We can probably stick to &client->dev or
>>> &priv->client->dev when a local client variable is not already
>>> available.
>>
>>
>> It is really your call as the driver's author to make if you want to use
>> the hwmon device or &client->dev.
>
> I've decided to stick with &client->dev for all dev_dbg(), while I
> would use the hwmon device for dev_notice() and dev_warn(), that are
> supposed to be eventually read by the user.
>
> However, while keeping an eye on the log messages I've realized that
> if the temperature remains out-of-limit for a lot of time, especially
> if the conversion rate is set fast, we tend to spam the log with alert
> messages.. I learned that you are usually concerned by noisy drivers,
> so I guess you might want to mitigate this..
>
> I could use dev_notice_once(), but it seems inappropriate here, or I
> can silence the message at least until one reads the chip. Lm90 does
> even disable the alarm until that happen, but it has only one alarm;
> here we have two, so it seems not correct here.
>
> Any suggestion?
>

Use a flag that shows if the attribute in question was read ?

Guenter

>
>>>
>>>
>>> Also, it looks like we can change some &priv->client->dev in
>>> &client->dev in probe function when calling i2c read/write functions.
>>>
>>> If you ACK, I'll fix and resend.
>>>
>> SGTM.
>>
>> Thanks,
>> Guenter
>>
>

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diff mbox

Patch

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index d1f82f2..8fdd241 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1448,6 +1448,16 @@  config SENSORS_SCH5636
 	  This driver can also be built as a module.  If so, the module
 	  will be called sch5636.
 
+config SENSORS_STTS751
+	tristate "ST Microelectronics STTS751"
+	depends on I2C
+	help
+	  If you say yes here you get support for STTS751
+	  temperature sensor chips.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called stts751.
+
 config SENSORS_SMM665
 	tristate "Summit Microelectronics SMM665"
 	depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 7476b22..1114130 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -147,6 +147,7 @@  obj-$(CONFIG_SENSORS_SMM665)	+= smm665.o
 obj-$(CONFIG_SENSORS_SMSC47B397)+= smsc47b397.o
 obj-$(CONFIG_SENSORS_SMSC47M1)	+= smsc47m1.o
 obj-$(CONFIG_SENSORS_SMSC47M192)+= smsc47m192.o
+obj-$(CONFIG_SENSORS_STTS751)	+= stts751.o
 obj-$(CONFIG_SENSORS_AMC6821)	+= amc6821.o
 obj-$(CONFIG_SENSORS_TC74)	+= tc74.o
 obj-$(CONFIG_SENSORS_THMC50)	+= thmc50.o
diff --git a/drivers/hwmon/stts751.c b/drivers/hwmon/stts751.c
new file mode 100644
index 0000000..4154294
--- /dev/null
+++ b/drivers/hwmon/stts751.c
@@ -0,0 +1,819 @@ 
+/*
+ * STTS751 sensor driver
+ *
+ * Copyright (C) 2016-2017 Istituto Italiano di Tecnologia - RBCS - EDL
+ * Robotics, Brain and Cognitive Sciences department
+ * Electronic Design Laboratory
+ *
+ * Written by Andrea Merello <andrea.merello@gmail.com>
+ *
+ * Based on  LM95241 driver and LM90 driver
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/bitops.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+#include <linux/sysfs.h>
+#include <linux/util_macros.h>
+
+#define DEVNAME "stts751"
+
+static const unsigned short normal_i2c[] = {
+	0x48, 0x49, 0x38, 0x39,  /* STTS751-0 */
+	0x4A, 0x4B, 0x3A, 0x3B,  /* STTS751-1 */
+	I2C_CLIENT_END };
+
+#define STTS751_REG_TEMP_H	0x00
+#define STTS751_REG_STATUS	0x01
+#define STTS751_STATUS_TRIPT	BIT(0)
+#define STTS751_STATUS_TRIPL	BIT(5)
+#define STTS751_STATUS_TRIPH	BIT(6)
+#define STTS751_REG_TEMP_L	0x02
+#define STTS751_REG_CONF	0x03
+#define STTS751_CONF_RES_MASK	0x0C
+#define STTS751_CONF_RES_SHIFT  2
+#define STTS751_CONF_EVENT_DIS  BIT(7)
+#define STTS751_CONF_STOP	BIT(6)
+#define STTS751_REG_RATE	0x04
+#define STTS751_REG_HLIM_H	0x05
+#define STTS751_REG_HLIM_L	0x06
+#define STTS751_REG_LLIM_H	0x07
+#define STTS751_REG_LLIM_L	0x08
+#define STTS751_REG_TLIM	0x20
+#define STTS751_REG_HYST	0x21
+#define STTS751_REG_SMBUS_TO	0x22
+
+#define STTS751_REG_PROD_ID	0xFD
+#define STTS751_REG_MAN_ID	0xFE
+#define STTS751_REG_REV_ID	0xFF
+
+#define STTS751_0_PROD_ID	0x00
+#define STTS751_1_PROD_ID	0x01
+#define ST_MAN_ID		0x53
+
+/*
+ * Possible update intervals are (in mS):
+ * 16000, 8000, 4000, 2000, 1000, 500, 250, 125, 62.5, 31.25
+ * However we are not going to complicate things too much and we stick to the
+ * approx value in mS.
+ */
+static const int stts751_intervals[] = {
+	16000, 8000, 4000, 2000, 1000, 500, 250, 125, 63, 31
+};
+
+static const struct i2c_device_id stts751_id[] = {
+	{ "stts751", 0 },
+	{ }
+};
+
+struct stts751_priv {
+	struct device *dev;
+	struct i2c_client *client;
+	struct mutex access_lock;
+	u8 interval;
+	int res;
+	int event_max, event_min;
+	int therm;
+	int hyst;
+	bool smbus_timeout;
+	int temp;
+	unsigned long last_update, last_alert_update;
+	u8 config;
+	bool min_alert, max_alert, therm_trip;
+	bool data_valid, alert_valid;
+};
+
+/*
+ * These functions converts temperature from HW format to integer format and
+ * vice-vers. They are (mostly) taken from lm90 driver. Unit is in mC.
+ */
+static int stts751_to_deg(s16 hw_val)
+{
+	return hw_val * 125 / 32;
+}
+
+static s32 stts751_to_hw(int val)
+{
+	return DIV_ROUND_CLOSEST(val, 125) * 32;
+}
+
+static int stts751_adjust_resolution(struct stts751_priv *priv)
+{
+	u8 res;
+
+	switch (priv->interval) {
+	case 9:
+		/* 10 bits */
+		res = 0;
+		break;
+	case 8:
+		/* 11 bits */
+		res = 1;
+		break;
+	default:
+		/* 12 bits */
+		res = 3;
+		break;
+	}
+
+	if (priv->res == res)
+		return 0;
+
+	priv->config &= ~STTS751_CONF_RES_MASK;
+	priv->config |= res << STTS751_CONF_RES_SHIFT;
+	dev_dbg(priv->dev, "setting res %d. config %x", res, priv->config);
+	priv->res = res;
+
+	return i2c_smbus_write_byte_data(priv->client,
+				STTS751_REG_CONF, priv->config);
+}
+
+static int stts751_update_temp(struct stts751_priv *priv)
+{
+	s32 integer1, integer2, frac;
+
+	/*
+	 * There is a trick here, like in the lm90 driver. We have to read two
+	 * registers to get the sensor temperature, but we have to beware a
+	 * conversion could occur between the readings. We could use the
+	 * one-shot conversion register, but we don't want to do this (disables
+	 * hardware monitoring). So the solution used here is to read the high
+	 * byte once, then the low byte, then the high byte again. If the new
+	 * high byte matches the old one, then we have a valid reading. Else we
+	 * have to read the low byte again, and now we believe we have a correct
+	 * reading.
+	 */
+	integer1 = i2c_smbus_read_byte_data(priv->client, STTS751_REG_TEMP_H);
+	if (integer1 < 0) {
+		dev_dbg(&priv->client->dev,
+			"I2C read failed (temp H). ret: %x\n", integer1);
+		return integer1;
+	}
+
+	frac = i2c_smbus_read_byte_data(priv->client, STTS751_REG_TEMP_L);
+	if (frac < 0) {
+		dev_dbg(&priv->client->dev,
+			"I2C read failed (temp L). ret: %x\n", frac);
+		return frac;
+	}
+
+	integer2 = i2c_smbus_read_byte_data(priv->client, STTS751_REG_TEMP_H);
+	if (integer2 < 0) {
+		dev_dbg(&priv->client->dev,
+			"I2C 2nd read failed (temp H). ret: %x\n", integer2);
+		return integer2;
+	}
+
+	if (integer1 != integer2) {
+		frac = i2c_smbus_read_byte_data(priv->client,
+						STTS751_REG_TEMP_L);
+		if (frac < 0) {
+			dev_dbg(&priv->client->dev,
+				"I2C 2nd read failed (temp L). ret: %x\n",
+				frac);
+			return frac;
+		}
+	}
+
+	priv->temp = stts751_to_deg((integer1 << 8) | frac);
+	return 0;
+}
+
+static int stts751_set_temp_reg16(struct stts751_priv *priv, int temp,
+				  u8 hreg, u8 lreg)
+{
+	s32 hwval;
+	int ret;
+
+	hwval = stts751_to_hw(temp);
+
+	ret = i2c_smbus_write_byte_data(priv->client, hreg, hwval >> 8);
+	if (ret)
+		return ret;
+
+	return i2c_smbus_write_byte_data(priv->client, lreg, hwval & 0xff);
+}
+
+static int stts751_set_temp_reg8(struct stts751_priv *priv, int temp, u8 reg)
+{
+	s32 hwval;
+
+	hwval = stts751_to_hw(temp);
+	return i2c_smbus_write_byte_data(priv->client, reg, hwval >> 8);
+}
+
+static int stts751_read_reg16(struct stts751_priv *priv, int *temp,
+			      u8 hreg, u8 lreg)
+{
+	int integer, frac;
+
+	integer = i2c_smbus_read_byte_data(priv->client, hreg);
+	if (integer < 0)
+		return integer;
+
+	frac = i2c_smbus_read_byte_data(priv->client, lreg);
+	if (frac < 0)
+		return frac;
+
+	*temp = stts751_to_deg((integer << 8) | frac);
+
+	return 0;
+}
+
+static int stts751_read_reg8(struct stts751_priv *priv, int *temp, u8 reg)
+{
+	int integer;
+
+	integer = i2c_smbus_read_byte_data(priv->client, reg);
+	if (integer < 0)
+		return integer;
+
+	*temp = stts751_to_deg(integer << 8);
+
+	return 0;
+}
+
+/*
+ * Update alert flags without waiting for cache to expire. We detects alerts
+ * immediately for the sake of the alert handler; we still need to deal with
+ * caching to workaround the fact that alarm flags int the status register,
+ * despite what the datasheet claims, gets always cleared on read.
+ */
+static int stts751_update_alert(struct stts751_priv *priv)
+{
+	int ret;
+	bool conv_done;
+	int cache_time = msecs_to_jiffies(stts751_intervals[priv->interval]);
+
+	/*
+	 * Add another 10% because if we run faster than the HW conversion
+	 * rate we will end up in reporting incorrectly alarms.
+	 */
+	cache_time += cache_time / 10;
+
+	ret = i2c_smbus_read_byte_data(priv->client, STTS751_REG_STATUS);
+	if (ret < 0)
+		return ret;
+
+	dev_dbg(priv->dev, "status reg %x\n", ret);
+	conv_done = ret & (STTS751_STATUS_TRIPH | STTS751_STATUS_TRIPL);
+	/*
+	 * Reset the cache if the cache time expired, or if we are sure
+	 * we have valid data from a device conversion, or if we know
+	 * our cache has been never written.
+	 *
+	 * Note that when the cache has been never written the point is
+	 * to correctly initialize the timestamp, rather than clearing
+	 * the cache values.
+	 *
+	 * Note that updating the cache timestamp when we get an alarm flag
+	 * is required, otherwise we could incorrectly report alarms to be zero.
+	 */
+	if (time_after(jiffies,	priv->last_alert_update + cache_time) ||
+	    conv_done || !priv->alert_valid) {
+		priv->max_alert = false;
+		priv->min_alert = false;
+		priv->alert_valid = true;
+		priv->last_alert_update = jiffies;
+		dev_dbg(priv->dev, "invalidating alert cache\n");
+	}
+
+	priv->max_alert |= !!(ret & STTS751_STATUS_TRIPH);
+	priv->min_alert |= !!(ret & STTS751_STATUS_TRIPL);
+	priv->therm_trip = !!(ret & STTS751_STATUS_TRIPT);
+
+	dev_dbg(priv->dev, "max_alert: %d, min_alert: %d, therm_trip: %d\n",
+		priv->max_alert, priv->min_alert, priv->therm_trip);
+
+	return 0;
+}
+
+static void stts751_alert(struct i2c_client *client,
+			  enum i2c_alert_protocol type, unsigned int data)
+{
+	int ret;
+	struct stts751_priv *priv = i2c_get_clientdata(client);
+
+	if (type != I2C_PROTOCOL_SMBUS_ALERT)
+		return;
+
+	dev_dbg(&client->dev, "alert!");
+
+	mutex_lock(&priv->access_lock);
+	ret = stts751_update_alert(priv);
+	if (ret < 0) {
+		/* default to worst case */
+		priv->max_alert = true;
+		priv->min_alert = true;
+
+		dev_warn(&priv->client->dev,
+			 "Alert received, but can't communicate to the device. Triggering all alarms!");
+	}
+
+	if (priv->max_alert) {
+		dev_notice(&client->dev, "got alert for HIGH temperature");
+
+		/* unblock alert poll */
+		sysfs_notify(&priv->dev->kobj, NULL, "temp1_max_alarm");
+	}
+
+	if (priv->min_alert) {
+		dev_notice(&client->dev, "got alert for LOW temperature");
+
+		/* unblock alert poll */
+		sysfs_notify(&priv->dev->kobj, NULL, "temp1_min_alarm");
+	}
+
+	if (priv->min_alert || priv->max_alert)
+		kobject_uevent(&priv->dev->kobj, KOBJ_CHANGE);
+
+	mutex_unlock(&priv->access_lock);
+}
+
+static int stts751_update(struct stts751_priv *priv)
+{
+	int ret = 0;
+	int cache_time = msecs_to_jiffies(stts751_intervals[priv->interval]);
+
+	mutex_lock(&priv->access_lock);
+	if (time_after(jiffies,	priv->last_update + cache_time) ||
+	    !priv->data_valid) {
+		ret = stts751_update_temp(priv);
+		if (ret)
+			goto exit;
+
+		ret = stts751_update_alert(priv);
+		if (ret)
+			goto exit;
+		priv->data_valid = true;
+		priv->last_update = jiffies;
+	}
+exit:
+	mutex_unlock(&priv->access_lock);
+
+	return ret;
+}
+
+static ssize_t show_max_alarm(struct device *dev, struct device_attribute *attr,
+			      char *buf)
+{
+	int ret;
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	ret = stts751_update(priv);
+	if (ret < 0)
+		return ret;
+
+	return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->max_alert);
+}
+
+static ssize_t show_min_alarm(struct device *dev, struct device_attribute *attr,
+			      char *buf)
+{
+	int ret;
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	ret = stts751_update(priv);
+	if (ret < 0)
+		return ret;
+
+	return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->min_alert);
+}
+
+static ssize_t show_input(struct device *dev, struct device_attribute *attr,
+			  char *buf)
+{
+	int ret;
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	ret = stts751_update(priv);
+	if (ret < 0)
+		return ret;
+
+	return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->temp);
+}
+
+static ssize_t show_therm(struct device *dev, struct device_attribute *attr,
+			  char *buf)
+{
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->therm);
+}
+
+static ssize_t set_therm(struct device *dev, struct device_attribute *attr,
+			 const char *buf, size_t count)
+{
+	int ret;
+	long temp;
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	if (kstrtol(buf, 10, &temp) < 0)
+		return -EINVAL;
+
+	/* HW works in range -64C to +127.937C */
+	temp = clamp_val(temp, -64000, 127937);
+	mutex_lock(&priv->access_lock);
+	ret = stts751_set_temp_reg8(priv, temp, STTS751_REG_TLIM);
+	if (ret)
+		goto exit;
+
+	dev_dbg(dev, "setting therm %ld", temp);
+
+	/*
+	 * hysteresis reg is relative to therm, so the HW does not need to be
+	 * adjusted, we need to update our local copy only.
+	 */
+	priv->hyst = temp - (priv->therm - priv->hyst);
+	priv->therm = temp;
+
+exit:
+	mutex_unlock(&priv->access_lock);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static ssize_t show_hyst(struct device *dev, struct device_attribute *attr,
+			 char *buf)
+{
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->hyst);
+}
+
+static ssize_t set_hyst(struct device *dev, struct device_attribute *attr,
+			const char *buf, size_t count)
+{
+	int ret;
+	long temp;
+
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	if (kstrtol(buf, 10, &temp) < 0)
+		return -EINVAL;
+
+	mutex_lock(&priv->access_lock);
+	/* HW works in range -64C to +127.937C */
+	temp = clamp_val(temp, -64000, priv->therm);
+	priv->hyst = temp;
+	dev_dbg(priv->dev, "setting hyst %ld", temp);
+	temp = priv->therm - temp;
+	ret = stts751_set_temp_reg8(priv, temp, STTS751_REG_HYST);
+	mutex_unlock(&priv->access_lock);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static ssize_t show_therm_trip(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	int ret;
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	ret = stts751_update(priv);
+	if (ret < 0)
+		return ret;
+
+	return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->therm_trip);
+}
+
+static ssize_t show_max(struct device *dev, struct device_attribute *attr,
+			char *buf)
+{
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->event_max);
+}
+
+static ssize_t set_max(struct device *dev, struct device_attribute *attr,
+		       const char *buf, size_t count)
+{
+	int ret;
+	long temp;
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	if (kstrtol(buf, 10, &temp) < 0)
+		return -EINVAL;
+
+	mutex_lock(&priv->access_lock);
+	/* HW works in range -64C to +127.937C */
+	temp = clamp_val(temp, priv->event_min, 127937);
+	ret = stts751_set_temp_reg16(priv, temp,
+				     STTS751_REG_HLIM_H, STTS751_REG_HLIM_L);
+	if (ret)
+		goto exit;
+
+	dev_dbg(dev, "setting event max %ld", temp);
+	priv->event_max = temp;
+	ret = count;
+exit:
+	mutex_unlock(&priv->access_lock);
+	return ret;
+}
+
+static ssize_t show_min(struct device *dev, struct device_attribute *attr,
+			char *buf)
+{
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE - 1, "%d\n", priv->event_min);
+}
+
+static ssize_t set_min(struct device *dev, struct device_attribute *attr,
+		       const char *buf, size_t count)
+{
+	int ret;
+	long temp;
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	if (kstrtol(buf, 10, &temp) < 0)
+		return -EINVAL;
+
+	mutex_lock(&priv->access_lock);
+	/* HW works in range -64C to +127.937C */
+	temp = clamp_val(temp, -64000, priv->event_max);
+	ret = stts751_set_temp_reg16(priv, temp,
+				     STTS751_REG_LLIM_H, STTS751_REG_LLIM_L);
+	if (ret)
+		goto exit;
+
+	dev_dbg(dev, "setting event min %ld", temp);
+	priv->event_min = temp;
+	ret = count;
+exit:
+	mutex_unlock(&priv->access_lock);
+	return ret;
+}
+
+static ssize_t show_interval(struct device *dev, struct device_attribute *attr,
+			     char *buf)
+{
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE - 1, "%d\n",
+			stts751_intervals[priv->interval]);
+}
+
+static ssize_t set_interval(struct device *dev, struct device_attribute *attr,
+			    const char *buf, size_t count)
+{
+	unsigned long val;
+	int idx;
+	int ret = count;
+	struct stts751_priv *priv = dev_get_drvdata(dev);
+
+	if (kstrtoul(buf, 10, &val) < 0)
+		return -EINVAL;
+
+	idx = find_closest_descending(val, stts751_intervals,
+				      ARRAY_SIZE(stts751_intervals));
+
+	dev_dbg(dev, "setting interval. req:%lu, idx: %d, val: %d", val, idx,
+		stts751_intervals[idx]);
+
+	mutex_lock(&priv->access_lock);
+	if (priv->interval == idx)
+		goto exit;
+
+	/*
+	 * In early development stages I've become suspicious about the chip
+	 * starting to misbehave if I ever set, even briefly, an invalid
+	 * configuration. While I'm not sure this is really needed, be
+	 * conservative and set rate/resolution in such an order that avoids
+	 * passing through an invalid configuration.
+	 */
+
+	/* speed up: lower the resolution, then modify convrate */
+	if (priv->interval < idx) {
+		dev_dbg(priv->dev, "lower resolution, then modify convrate");
+		priv->interval = idx;
+		ret = stts751_adjust_resolution(priv);
+		if (ret)
+			goto exit;
+	}
+
+	ret = i2c_smbus_write_byte_data(priv->client, STTS751_REG_RATE, idx);
+	if (ret)
+		goto exit;
+	/* slow down: modify convrate, then raise resolution */
+	if (priv->interval != idx) {
+		dev_dbg(priv->dev, "modify convrate, then raise resolution");
+		priv->interval = idx;
+		ret = stts751_adjust_resolution(priv);
+		if (ret)
+			goto exit;
+	}
+	ret = count;
+exit:
+	mutex_unlock(&priv->access_lock);
+
+	return ret;
+}
+
+static int stts751_detect(struct i2c_client *new_client,
+			  struct i2c_board_info *info)
+{
+	struct i2c_adapter *adapter = new_client->adapter;
+	const char *name;
+	int tmp;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -ENODEV;
+
+	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_MAN_ID);
+	if (tmp != ST_MAN_ID)
+		return -ENODEV;
+
+	/* lower temperaure registers always have bits 0-3 set to zero */
+	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_TEMP_L);
+	if (tmp & 0xf)
+		return -ENODEV;
+
+	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_HLIM_L);
+	if (tmp & 0xf)
+		return -ENODEV;
+
+	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_LLIM_L);
+	if (tmp & 0xf)
+		return -ENODEV;
+
+	/* smbus timeout register always have bits 0-7 set to zero */
+	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_SMBUS_TO);
+	if (tmp & 0x7f)
+		return -ENODEV;
+
+	tmp = i2c_smbus_read_byte_data(new_client, STTS751_REG_PROD_ID);
+
+	switch (tmp) {
+	case STTS751_0_PROD_ID:
+		name = "STTS751-0";
+		break;
+	case STTS751_1_PROD_ID:
+		name = "STTS751-1";
+		break;
+	default:
+		return -ENODEV;
+	}
+	dev_dbg(&new_client->dev, "Chip %s detected", name);
+
+	strlcpy(info->type, stts751_id[0].name, I2C_NAME_SIZE);
+	return 0;
+}
+
+static int stts751_read_chip_config(struct stts751_priv *priv)
+{
+	int ret;
+	int tmp;
+
+	ret = i2c_smbus_read_byte_data(priv->client, STTS751_REG_CONF);
+	if (ret < 0)
+		return ret;
+	priv->config = ret;
+	priv->res = (ret & STTS751_CONF_RES_MASK) >> STTS751_CONF_RES_SHIFT;
+
+	ret = i2c_smbus_read_byte_data(priv->client, STTS751_REG_RATE);
+	if (ret < 0)
+		return ret;
+	priv->interval = ret;
+
+	ret = stts751_read_reg16(priv, &priv->event_max,
+				 STTS751_REG_HLIM_H, STTS751_REG_HLIM_L);
+	if (ret)
+		return ret;
+
+	ret = stts751_read_reg16(priv, &priv->event_min,
+				 STTS751_REG_LLIM_H, STTS751_REG_LLIM_L);
+	if (ret)
+		return ret;
+
+	ret = stts751_read_reg8(priv, &priv->therm, STTS751_REG_TLIM);
+	if (ret)
+		return ret;
+
+	ret = stts751_read_reg8(priv, &tmp, STTS751_REG_HYST);
+	if (ret)
+		return ret;
+	priv->hyst = priv->therm - tmp;
+
+	return 0;
+}
+
+static SENSOR_DEVICE_ATTR(temp1_input, 0444, show_input, NULL, 0);
+static SENSOR_DEVICE_ATTR(temp1_min, 0644, show_min, set_min, 0);
+static SENSOR_DEVICE_ATTR(temp1_max, 0644, show_max, set_max, 0);
+static SENSOR_DEVICE_ATTR(temp1_min_alarm, 0444, show_min_alarm, NULL, 0);
+static SENSOR_DEVICE_ATTR(temp1_max_alarm, 0444, show_max_alarm, NULL, 0);
+static SENSOR_DEVICE_ATTR(temp1_crit, 0644, show_therm,	set_therm, 0);
+static SENSOR_DEVICE_ATTR(temp1_crit_hyst, 0644, show_hyst, set_hyst, 0);
+static SENSOR_DEVICE_ATTR(temp1_crit_alarm, 0444, show_therm_trip, NULL, 0);
+static SENSOR_DEVICE_ATTR(update_interval, 0644,
+			  show_interval, set_interval, 0);
+
+static struct attribute *stts751_attrs[] = {
+	&sensor_dev_attr_temp1_input.dev_attr.attr,
+	&sensor_dev_attr_temp1_min.dev_attr.attr,
+	&sensor_dev_attr_temp1_max.dev_attr.attr,
+	&sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
+	&sensor_dev_attr_temp1_crit.dev_attr.attr,
+	&sensor_dev_attr_temp1_crit_hyst.dev_attr.attr,
+	&sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
+	&sensor_dev_attr_update_interval.dev_attr.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(stts751);
+
+static int stts751_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct stts751_priv *priv;
+	int ret;
+	bool smbus_nto;
+	int rev_id;
+
+	priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->client = client;
+	i2c_set_clientdata(client, priv);
+	mutex_init(&priv->access_lock);
+
+	if (device_property_present(&client->dev,
+				    "smbus-timeout-disable")) {
+		smbus_nto = device_property_read_bool(&client->dev,
+						      "smbus-timeout-disable");
+
+		ret = i2c_smbus_write_byte_data(priv->client,
+						STTS751_REG_SMBUS_TO,
+						smbus_nto ? 0 : 0x80);
+		if (ret)
+			return ret;
+	}
+
+	rev_id = i2c_smbus_read_byte_data(priv->client, STTS751_REG_REV_ID);
+	if (rev_id < 0)
+		return -ENODEV;
+	if (rev_id != 0x1) {
+		dev_dbg(&priv->client->dev, "Chip revision 0x%x is untested\n",
+			rev_id);
+	}
+
+	ret = stts751_read_chip_config(priv);
+	if (ret)
+		return ret;
+
+	priv->config &= ~(STTS751_CONF_STOP | STTS751_CONF_EVENT_DIS);
+	ret = i2c_smbus_write_byte_data(priv->client,
+					STTS751_REG_CONF, priv->config);
+	if (ret)
+		return ret;
+
+	priv->dev = devm_hwmon_device_register_with_groups(&client->dev,
+							client->name, priv,
+							stts751_groups);
+	return PTR_ERR_OR_ZERO(priv->dev);
+}
+
+MODULE_DEVICE_TABLE(i2c, stts751_id);
+
+static struct i2c_driver stts751_driver = {
+	.class		= I2C_CLASS_HWMON,
+	.driver = {
+		.name	= DEVNAME,
+	},
+	.probe		= stts751_probe,
+	.id_table	= stts751_id,
+	.detect		= stts751_detect,
+	.alert		= stts751_alert,
+	.address_list	= normal_i2c,
+};
+
+module_i2c_driver(stts751_driver);
+
+MODULE_AUTHOR("Andrea Merello <andrea.merello@gmail.com>");
+MODULE_DESCRIPTION("STTS751 sensor driver");
+MODULE_LICENSE("GPL");