This patch adds a HWMON driver for ST Microelectronics STTS751
temperature sensors.

It does support temperature reading (of course), SMBUS alert
functionality and "therm" output.

Thanks-to: LABBE Corentin [for suggestions]
Thanks-to: Guenter Roeck [for suggestions/discussions]
Signed-off-by: Andrea Merello <andrea.mere...@gmail.com>
Cc: LABBE Corentin <clabbe.montj...@gmail.com>
Cc: Guenter Roeck <li...@roeck-us.net>
Cc: Jean Delvare <jdelv...@suse.com>
---
 drivers/hwmon/Kconfig   |  12 +-
 drivers/hwmon/Makefile  |   2 +-
 drivers/hwmon/stts751.c | 805 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 817 insertions(+), 2 deletions(-)
 create mode 100644 drivers/hwmon/stts751.c

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index eaf2f91..4e70b42 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
@@ -1506,7 +1516,7 @@ config SENSORS_ADS7871
 
 config SENSORS_AMC6821
        tristate "Texas Instruments AMC6821"
-       depends on I2C 
+       depends on I2C
        help
          If you say yes here you get support for the Texas Instruments
          AMC6821 hardware monitoring chips.
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index fe87d28..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
@@ -169,4 +170,3 @@ obj-$(CONFIG_SENSORS_WM8350)        += wm8350-hwmon.o
 obj-$(CONFIG_PMBUS)            += pmbus/
 
 ccflags-$(CONFIG_HWMON_DEBUG_CHIP) := -DDEBUG
-
diff --git a/drivers/hwmon/stts751.c b/drivers/hwmon/stts751.c
new file mode 100644
index 0000000..8358e04
--- /dev/null
+++ b/drivers/hwmon/stts751.c
@@ -0,0 +1,805 @@
+/*
+ * STTS751 sensor driver
+ *
+ * Copyright (C) 2016 Istituto Italiano di Tecnologia - RBCS - EDL
+ * Robotics, Brain and Cognitive Sciences department
+ * Electronic Design Laboratory
+ *
+ * Written by Andrea Merello <andrea.mere...@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/of_irq.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_TRIPL   BIT(5)
+#define STTS751_STATUS_TRIPH   BIT(6)
+#define STTS751_STATUS_BUSY    BIT(8)
+#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_ONESHOT    0x0F
+#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
+
+/* stick with HW defaults */
+#define STTS751_THERM_DEFAULT  85000
+#define STTS751_HYST_DEFAULT   10000
+#define STTS751_EVENT_MAX_DEFAULT 85000
+#define STTS751_EVENT_MIN_DEFAULT 0
+
+#define STTS751_RACE_RETRY     5
+#define STTS751_CONV_TIMEOUT   100 /* mS */
+#define STTS751_CACHE_TIME     100 /* mS */
+
+/*
+ * 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
+};
+
+struct stts751_priv {
+       struct device *dev;
+       struct i2c_client *client;
+       struct mutex access_lock;
+       unsigned long interval;
+       int res;
+       bool gen_therm, gen_event;
+       int event_max, event_min;
+       int therm;
+       int hyst;
+       bool smbus_timeout;
+       int temp;
+       unsigned long last_update;
+       u8 config;
+       bool min_alert, max_alert;
+       bool data_valid;
+
+       /*
+        * Temperature/interval is always present.
+        * Depending by DT therm and event are dynamically added.
+        * There are max 4 entries plus the guard
+        */
+       const struct attribute_group *groups[5];
+};
+
+/*
+ * 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(s32 hw_val)
+{
+       return hw_val * 125 / 32;
+}
+
+static s16 stts751_to_hw(int val, s32 *hw_val)
+{
+       /* HW works in range -64C to +127C */
+       if ((val > 127000) || (val < -64000))
+               return -EINVAL;
+
+       if (val < 0)
+               *hw_val = (val - 62) / 125 * 32;
+       else
+               *hw_val = (val + 62) / 125 * 32;
+
+       return 0;
+}
+
+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;
+
+       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;
+       int ret = 0;
+
+       mutex_lock(&priv->access_lock);
+
+       /*
+        * 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", ret);
+               ret = integer1;
+               goto exit;
+       }
+
+       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", ret);
+               ret = frac;
+               goto exit;
+       }
+
+       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", ret);
+               ret = integer2;
+               goto exit;
+       }
+
+       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", ret);
+                       ret = frac;
+                       goto exit;
+               }
+       }
+
+exit:
+       mutex_unlock(&priv->access_lock);
+       if (ret)
+               return ret;
+
+       priv->temp = stts751_to_deg((integer1 << 8) | frac);
+       return ret;
+}
+
+static int stts751_set_temp_reg(struct stts751_priv *priv, int temp,
+                               bool is_frac, u8 hreg, u8 lreg)
+{
+       s32 hwval;
+       int ret;
+
+       if (stts751_to_hw(temp, &hwval))
+               return -EINVAL;
+
+       mutex_lock(&priv->access_lock);
+       ret = i2c_smbus_write_byte_data(priv->client, hreg, hwval >> 8);
+       if (ret)
+               goto exit;
+       if (is_frac)
+               ret = i2c_smbus_write_byte_data(priv->client,
+                                               lreg, hwval & 0xff);
+exit:
+       mutex_unlock(&priv->access_lock);
+
+       return ret;
+}
+
+static int stts751_update_alert(struct stts751_priv *priv)
+{
+       int ret;
+
+       /* not for us.. */
+       if (!priv->gen_event)
+               return 0;
+
+       ret = i2c_smbus_read_byte_data(priv->client, STTS751_REG_STATUS);
+
+       if (ret < 0)
+               return ret;
+
+       priv->max_alert = priv->max_alert || !!(ret & STTS751_STATUS_TRIPH);
+       priv->min_alert = priv->min_alert || !!(ret & STTS751_STATUS_TRIPL);
+
+       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);
+       bool prev_max = priv->max_alert;
+       bool prev_min = priv->min_alert;
+
+       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;
+
+               if (!(prev_max && prev_min)) {
+                       dev_warn(&priv->client->dev,
+                               "Alert received, but can't communicate to the 
device. Something bad happening? Triggering all alarms!");
+               }
+       }
+
+       if (!prev_max && priv->max_alert) {
+               dev_notice(&client->dev, "got alert for HIGH temperature");
+
+               /* unblock alert poll */
+               sysfs_notify(&priv->dev->kobj, NULL, "temp1_event_max_alert");
+               kobject_uevent(&priv->dev->kobj, KOBJ_CHANGE);
+       }
+
+       if (!prev_min && priv->min_alert) {
+               dev_notice(&client->dev, "got alert for LOW temperature");
+
+               /* unblock alert poll */
+               sysfs_notify(&priv->dev->kobj, NULL, "temp1_event_min_alert");
+               kobject_uevent(&priv->dev->kobj, KOBJ_CHANGE);
+       }
+       mutex_unlock(&priv->access_lock);
+}
+
+static ssize_t show_max_alert(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->max_alert);
+}
+
+static ssize_t set_max_alert(struct device *dev, struct device_attribute *attr,
+                      const char *buf, size_t count)
+{
+       struct stts751_priv *priv = dev_get_drvdata(dev);
+
+       mutex_lock(&priv->access_lock);
+       priv->max_alert = false;
+       mutex_unlock(&priv->access_lock);
+
+       return count;
+}
+
+static ssize_t show_min_alert(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->min_alert);
+}
+
+static ssize_t set_min_alert(struct device *dev, struct device_attribute *attr,
+                      const char *buf, size_t count)
+{
+       struct stts751_priv *priv = dev_get_drvdata(dev);
+
+       mutex_lock(&priv->access_lock);
+       priv->min_alert = false;
+       mutex_unlock(&priv->access_lock);
+
+       return count;
+}
+
+static ssize_t show_input(struct device *dev, struct device_attribute *attr,
+                         char *buf)
+{
+       int ret;
+       int cache_time = STTS751_CACHE_TIME * HZ / 1000;
+       struct stts751_priv *priv = dev_get_drvdata(dev);
+
+       /*
+        * Adjust the cache time wrt the sample rate. We do 4X in order to get
+        * a new measure in no more than 1/4 of the sample time (that seemed
+        * reasonable to me).
+        */
+       cache_time = stts751_intervals[priv->interval] / 4 * HZ / 1000;
+
+       if (time_after(jiffies, priv->last_update + cache_time) ||
+               !priv->data_valid) {
+               ret = stts751_update_temp(priv);
+               if (ret)
+                       return ret;
+               priv->last_update = jiffies;
+               priv->data_valid = true;
+       }
+
+       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;
+
+       ret = stts751_set_temp_reg(priv, temp, false, STTS751_REG_TLIM, 0);
+       if (ret)
+               return ret;
+
+       dev_dbg(dev, "setting therm %ld", temp);
+
+       priv->therm = temp;
+       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;
+
+       ret = stts751_set_temp_reg(priv, temp, false, STTS751_REG_HYST, 0);
+       if (ret)
+               return ret;
+
+       dev_dbg(dev, "setting hyst %ld", temp);
+
+       priv->hyst = temp;
+       return count;
+}
+
+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;
+
+       ret = stts751_set_temp_reg(priv, temp, true,
+                               STTS751_REG_HLIM_H, STTS751_REG_HLIM_L);
+       if (ret)
+               return ret;
+
+       dev_dbg(dev, "setting event max %ld", temp);
+       priv->event_max = temp;
+       return count;
+}
+
+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;
+
+       ret = stts751_set_temp_reg(priv, temp, true,
+                               STTS751_REG_LLIM_H, STTS751_REG_LLIM_L);
+       if (ret)
+               return ret;
+
+       dev_dbg(dev, "setting event min %ld", temp);
+
+       priv->event_min = temp;
+       return count;
+}
+
+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 = 0;
+       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]);
+
+       if (priv->interval == idx)
+               return count;
+
+       mutex_lock(&priv->access_lock);
+
+       /* speed up, lower the resolution, then modify convrate */
+       if (priv->interval < idx) {
+               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) {
+               priv->interval = idx;
+               ret = stts751_adjust_resolution(priv);
+               if (ret)
+                       goto exit;
+
+       }
+exit:
+       mutex_unlock(&priv->access_lock);
+
+       return count;
+}
+
+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 mfg_id, prod_id, rev_id;
+
+       if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+               return -ENODEV;
+
+       mfg_id = i2c_smbus_read_byte_data(new_client, ST_MAN_ID);
+       if (mfg_id != ST_MAN_ID)
+               return -ENODEV;
+
+       prod_id = i2c_smbus_read_byte_data(new_client, STTS751_REG_PROD_ID);
+
+       switch (prod_id) {
+       case STTS751_0_PROD_ID:
+               name = "STTS751-0";
+               break;
+       case STTS751_1_PROD_ID:
+               name = "STTS751-1";
+               break;
+       default:
+               return -ENODEV;
+       }
+       dev_info(&new_client->dev, "Chip %s detected!", name);
+
+       rev_id = i2c_smbus_read_byte_data(new_client, STTS751_REG_REV_ID);
+
+       if (rev_id != 0x1) {
+               dev_notice(&new_client->dev,
+                       "Chip revision 0x%x is untested\nPlease report whether 
it works to andrea.mere...@gmail.com",
+                       rev_id);
+       }
+
+       strlcpy(info->type, name, I2C_NAME_SIZE);
+       return 0;
+}
+
+static int stts751_init_chip(struct stts751_priv *priv)
+{
+       int ret;
+
+       priv->config = STTS751_CONF_EVENT_DIS | STTS751_CONF_STOP;
+       ret = i2c_smbus_write_byte_data(priv->client, STTS751_REG_CONF,
+                                       priv->config);
+       if (ret)
+               return ret;
+
+       ret = i2c_smbus_write_byte_data(priv->client, STTS751_REG_RATE,
+                                       priv->interval);
+       if (ret)
+               return ret;
+
+       /* invalid, to force update */
+       priv->res = -1;
+       ret = stts751_adjust_resolution(priv);
+       if (ret)
+               return ret;
+
+       ret = i2c_smbus_write_byte_data(priv->client,
+                                       STTS751_REG_SMBUS_TO,
+                                       priv->smbus_timeout ? 0x80 : 0);
+       if (ret)
+               return ret;
+
+
+       if (priv->gen_event) {
+               ret = stts751_set_temp_reg(priv, priv->event_max, true,
+                                       STTS751_REG_HLIM_H, STTS751_REG_HLIM_L);
+               if (ret)
+                       return ret;
+
+               ret = stts751_set_temp_reg(priv, priv->event_min, true,
+                                       STTS751_REG_LLIM_H, STTS751_REG_LLIM_L);
+               if (ret)
+                       return ret;
+               priv->config &= ~STTS751_CONF_EVENT_DIS;
+       }
+
+       if (priv->gen_therm) {
+               ret = stts751_set_temp_reg(priv, priv->therm, false,
+                                       STTS751_REG_TLIM, 0);
+               if (ret)
+                       return ret;
+
+               ret = stts751_set_temp_reg(priv, priv->hyst, false,
+                                       STTS751_REG_HYST, 0);
+               if (ret)
+                       return ret;
+       }
+
+       priv->config &= ~STTS751_CONF_STOP;
+       ret = i2c_smbus_write_byte_data(priv->client,
+                                       STTS751_REG_CONF, priv->config);
+
+       return ret;
+}
+
+static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_input, NULL, 0);
+static SENSOR_DEVICE_ATTR(temp1_event_min, S_IWUSR | S_IRUGO,
+                       show_min, set_min, 0);
+static SENSOR_DEVICE_ATTR(temp1_event_max, S_IWUSR | S_IRUGO,
+                       show_max, set_max, 0);
+static SENSOR_DEVICE_ATTR(temp1_event_min_alert, S_IWUSR | S_IRUGO,
+                       show_min_alert, set_min_alert, 0);
+static SENSOR_DEVICE_ATTR(temp1_event_max_alert, S_IWUSR | S_IRUGO,
+                       show_max_alert, set_max_alert, 0);
+static SENSOR_DEVICE_ATTR(temp1_therm, S_IWUSR | S_IRUGO, show_therm,
+                       set_therm, 0);
+static SENSOR_DEVICE_ATTR(temp1_therm_hyst, S_IWUSR | S_IRUGO, show_hyst,
+                       set_hyst, 0);
+static SENSOR_DEVICE_ATTR(update_interval, S_IWUSR | S_IRUGO,
+                       show_interval, set_interval, 0);
+
+/* always present */
+static struct attribute *stts751_temp_attrs[] = {
+       &sensor_dev_attr_temp1_input.dev_attr.attr,
+       NULL
+};
+
+static struct attribute_group stts751_temp_group = {
+       .attrs = stts751_temp_attrs,
+};
+
+/* present when therm pin or event pin are connected */
+static struct attribute *stts751_interval_attrs[] = {
+       &sensor_dev_attr_update_interval.dev_attr.attr,
+       NULL
+};
+
+static struct attribute_group stts751_interval_group = {
+       .attrs = stts751_interval_attrs,
+};
+
+/* present when event pin is connected */
+static struct attribute *stts751_event_attrs[] = {
+       &sensor_dev_attr_temp1_event_min.dev_attr.attr,
+       &sensor_dev_attr_temp1_event_max.dev_attr.attr,
+       &sensor_dev_attr_temp1_event_min_alert.dev_attr.attr,
+       &sensor_dev_attr_temp1_event_max_alert.dev_attr.attr,
+       NULL
+};
+
+static struct attribute_group stts751_event_group = {
+       .attrs = stts751_event_attrs,
+};
+
+/* present when therm pin is connected */
+static struct attribute *stts751_therm_attrs[] = {
+       &sensor_dev_attr_temp1_therm.dev_attr.attr,
+       &sensor_dev_attr_temp1_therm_hyst.dev_attr.attr,
+       NULL
+};
+
+static struct attribute_group stts751_therm_group = {
+       .attrs = stts751_therm_attrs,
+};
+
+static int stts751_probe(struct i2c_client *client,
+                        const struct i2c_device_id *id)
+{
+       struct stts751_priv *priv;
+       int ret;
+       int groups_idx = 0;
+       struct device_node *np = client->dev.of_node;
+
+       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);
+
+       /* default to 2 samples per second */
+       priv->interval = 5;
+       /* default to timeout enable, as per chip default */
+       priv->smbus_timeout = true;
+       priv->last_update = 0;
+       priv->data_valid = false;
+       priv->max_alert = false;
+       priv->min_alert = false;
+       priv->gen_therm = false;
+       priv->gen_event = false;
+       priv->therm = STTS751_THERM_DEFAULT;
+       priv->hyst = STTS751_HYST_DEFAULT;
+       priv->event_max = STTS751_EVENT_MAX_DEFAULT;
+       priv->event_min = STTS751_EVENT_MIN_DEFAULT;
+
+       if (np) {
+               priv->gen_therm = of_property_read_bool(np, "has-therm");
+               priv->gen_event = of_property_read_bool(np, "has-event");
+               priv->smbus_timeout = !of_property_read_bool(np,
+                                               "smbus-timeout-disable");
+       } else {
+               dev_notice(&client->dev, "No DT data. Event/therm disabled\n");
+       }
+
+       dev_dbg(&client->dev, "gen_event: %s, gen_therm: %s",
+               priv->gen_event ? "YES" : "NO",
+               priv->gen_therm ? "YES" : "NO");
+
+       priv->groups[groups_idx++] = &stts751_temp_group;
+       priv->groups[groups_idx++] = &stts751_interval_group;
+
+       if (priv->gen_therm)
+               priv->groups[groups_idx++] = &stts751_therm_group;
+
+       if (priv->gen_event)
+               priv->groups[groups_idx++] = &stts751_event_group;
+
+       priv->groups[groups_idx] = NULL;
+
+       ret = stts751_init_chip(priv);
+       if (ret)
+               return ret;
+
+       priv->dev = devm_hwmon_device_register_with_groups(&client->dev,
+                                                       client->name, priv,
+                                                       priv->groups);
+       return PTR_ERR_OR_ZERO(priv->dev);
+}
+
+static const struct i2c_device_id stts751_id[] = {
+       { "stts751", 0 },
+       { }
+};
+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.mere...@gmail.com>");
+MODULE_DESCRIPTION("STTS751 sensor driver");
+MODULE_LICENSE("GPL");
-- 
2.7.4

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