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[PATCH 1/1 v3] hwmon: add support for Sensirion SHT3x sensors

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[PATCH 1/1 v3] hwmon: add support for Sensirion SHT3x sensors

Pascal Sachs-2
From: David Frey <[hidden email]>

This driver implements support for the Sensirion SHT3x-DIS chip,
a humidity and temperature sensor. Temperature is measured
in degrees celsius, relative humidity is expressed as a percentage.
In the sysfs interface, all values are scaled by 1000,
i.e. the value for 31.5 degrees celsius is 31500.

Signed-off-by: Pascal Sachs <[hidden email]>
---
Patch was generated against kernel v4.6-rc7

 Documentation/hwmon/sht3x           |  72 ++++
 drivers/hwmon/Kconfig               |  11 +
 drivers/hwmon/Makefile              |   1 +
 drivers/hwmon/sht3x.c               | 701 ++++++++++++++++++++++++++++++++++++
 include/linux/platform_data/sht3x.h |  25 ++
 5 files changed, 810 insertions(+)
 create mode 100644 Documentation/hwmon/sht3x
 create mode 100644 drivers/hwmon/sht3x.c
 create mode 100644 include/linux/platform_data/sht3x.h

diff --git a/Documentation/hwmon/sht3x b/Documentation/hwmon/sht3x
new file mode 100644
index 0000000..f5aa633
--- /dev/null
+++ b/Documentation/hwmon/sht3x
@@ -0,0 +1,72 @@
+Kernel driver sht3x
+===================
+
+Supported chips:
+  * Sensirion SHT3x-DIS
+    Prefix: 'sht3x'
+    Addresses scanned: none
+    Datasheet: http://www.sensirion.com/fileadmin/user_upload/customers/sensirion/Dokumente/Humidity/Sensirion_Humidity_Datasheet_SHT3x_DIS.pdf
+
+Author:
+  David Frey <[hidden email]>
+  Pascal Sachs <[hidden email]>
+
+Description
+-----------
+
+This driver implements support for the Sensirion SHT3x-DIS chip, a humidity
+and temperature sensor. Temperature is measured in degrees celsius, relative
+humidity is expressed as a percentage. In the sysfs interface, all values are
+scaled by 1000, i.e. the value for 31.5 degrees celsius is 31500.
+
+The device communicates with the I2C protocol. Sensors can have the I2C
+addresses 0x44 or 0x45, depending on the wiring. See
+Documentation/i2c/instantiating-devices for methods to instantiate the device.
+
+There are two options configurable by means of sht3x_platform_data:
+1. blocking (pull the I2C clock line down while performing the measurement) or
+   non-blocking mode. Blocking mode will guarantee the fastest result but
+   the I2C bus will be busy during that time. By default, non-blocking mode
+   is used. Make sure clock-stretching works properly on your device if you
+   want to use blocking mode.
+2. high or low accuracy. High accuracy is used by default and using it is
+   strongly recommended.
+
+The sht3x sensor supports a single shot mode as well as 5 periodic measure
+modes, which can be controlled with the update_interval sysfs interface.
+The allowed update_interval in milliseconds are as follows:
+  *     0   single shot mode
+  *  2000   0.5 Hz periodic measurement
+  *  1000   1   Hz periodic measurement
+  *   500   2   Hz periodic measurement
+  *   250   4   Hz periodic measurement
+  *   100  10   Hz periodic measurement
+
+In the periodic measure mode, the sensor automatically triggers a measurement
+with the configured update interval on the chip. When a temperature or humidity
+reading exceeds the configured limits, the alert attribute is set to 1 and
+the alert pin on the sensor is set to high.
+When the temperature and humidity readings move back between the hysteresis
+values, the alert bit is set to 0 and the alert pin on the sensor is set to
+low.
+
+sysfs-Interface
+---------------
+
+temp1_input:        temperature input
+humidity1_input:    humidity input
+temp1_max:          temperature max value
+temp1_max_hyst:     temperature hysteresis value for max limit
+humidity1_max:      humidity max value
+humidity1_max_hyst: humidity hysteresis value for max limit
+temp1_min:          temperature min value
+temp1_min_hyst:     temperature hysteresis value for min limit
+humidity1_min:      humidity min value
+humidity1_min_hyst: humidity hysteresis value for min limit
+temp1_alarm:        alarm flag is set to 1 if the temperature is outside the
+                    configured limits. Alarm only works in periodic measure mode
+humidity1_alarm:    alarm flag is set to 1 if the humidity is outside the
+                    configured limits. Alarm only works in periodic measure mode
+update_interval:    update interval, 0 for single shot, interval in msec
+                    for periodic measurement. If the interval is not supported
+                    by the sensor, the next faster interval is chosen
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 5c2d13a..222c483 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1254,6 +1254,17 @@ config SENSORS_SHT21
   This driver can also be built as a module.  If so, the module
   will be called sht21.
 
+config SENSORS_SHT3x
+ tristate "Sensiron humidity and temperature sensors. SHT3x and compat."
+ depends on I2C
+ select CRC8
+ help
+  If you say yes here you get support for the Sensiron SHT30 and SHT31
+  humidity and temperature sensors.
+
+  This driver can also be built as a module.  If so, the module
+  will be called sht3x.
+
 config SENSORS_SHTC1
  tristate "Sensiron humidity and temperature sensors. SHTC1 and compat."
  depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 58cc3ac..999ff2d 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -137,6 +137,7 @@ obj-$(CONFIG_SENSORS_SCH5627) += sch5627.o
 obj-$(CONFIG_SENSORS_SCH5636) += sch5636.o
 obj-$(CONFIG_SENSORS_SHT15) += sht15.o
 obj-$(CONFIG_SENSORS_SHT21) += sht21.o
+obj-$(CONFIG_SENSORS_SHT3x) += sht3x.o
 obj-$(CONFIG_SENSORS_SHTC1) += shtc1.o
 obj-$(CONFIG_SENSORS_SIS5595) += sis5595.o
 obj-$(CONFIG_SENSORS_SMM665) += smm665.o
diff --git a/drivers/hwmon/sht3x.c b/drivers/hwmon/sht3x.c
new file mode 100644
index 0000000..a3d2130
--- /dev/null
+++ b/drivers/hwmon/sht3x.c
@@ -0,0 +1,701 @@
+/* Sensirion SHT3x-DIS humidity and temperature sensor driver.
+ * The SHT3x comes in many different versions, this driver is for the
+ * I2C version only.
+ *
+ * Copyright (C) 2016 Sensirion AG, Switzerland
+ * Author: David Frey <[hidden email]>
+ * Author: Pascal Sachs <[hidden email]>
+ *
+ * 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 <asm/page.h>
+#include <linux/crc8.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/jiffies.h>
+#include <linux/platform_data/sht3x.h>
+
+/* commands (high precision mode) */
+static const unsigned char sht3x_cmd_measure_blocking_hpm[]    = { 0x2c, 0x06 };
+static const unsigned char sht3x_cmd_measure_nonblocking_hpm[] = { 0x24, 0x00 };
+
+/* commands (low power mode) */
+static const unsigned char sht3x_cmd_measure_blocking_lpm[]    = { 0x2c, 0x10 };
+static const unsigned char sht3x_cmd_measure_nonblocking_lpm[] = { 0x24, 0x16 };
+
+/* commands for periodic mode */
+static const unsigned char sht3x_cmd_measure_periodic_mode[]   = { 0xe0, 0x00 };
+static const unsigned char sht3x_cmd_break[]                   = { 0x30, 0x93 };
+
+/* other commands */
+static const unsigned char sht3x_cmd_read_status_reg[]         = { 0xf3, 0x2d };
+static const unsigned char sht3x_cmd_clear_status_reg[]        = { 0x30, 0x41 };
+
+/* delays for non-blocking i2c commands, both in us */
+#define SHT3X_NONBLOCKING_WAIT_TIME_HPM  15000
+#define SHT3X_NONBLOCKING_WAIT_TIME_LPM   4000
+
+#define SHT3X_WORD_LEN         2
+#define SHT3X_CMD_LENGTH       2
+#define SHT3X_CRC8_LEN         1
+#define SHT3X_RESPONSE_LENGTH  6
+#define SHT3X_CRC8_POLYNOMIAL  0x31
+#define SHT3X_CRC8_INIT        0xFF
+
+enum sht3x_chips {
+ sht3x,
+ sts3x,
+};
+
+DECLARE_CRC8_TABLE(sht3x_crc8_table);
+
+/* periodic measure commands (high precision mode) */
+static const char periodic_measure_commands_hpm[][SHT3X_CMD_LENGTH] = {
+ /* 0.5 measurements per second */
+ {0x20, 0x32},
+ /* 1 measurements per second */
+ {0x21, 0x30},
+ /* 2 measurements per second */
+ {0x22, 0x36},
+ /* 4 measurements per second */
+ {0x23, 0x34},
+ /* 10 measurements per second */
+ {0x27, 0x37},
+};
+
+/* periodic measure commands (low power mode) */
+static const char periodic_measure_commands_lpm[][SHT3X_CMD_LENGTH] = {
+ /* 0.5 measurements per second */
+ {0x20, 0x2f},
+ /* 1 measurements per second */
+ {0x21, 0x2d},
+ /* 2 measurements per second */
+ {0x22, 0x2b},
+ /* 4 measurements per second */
+ {0x23, 0x29},
+ /* 10 measurements per second */
+ {0x27, 0x2a},
+};
+
+struct sht3x_limit_commands {
+ const char read_command[SHT3X_CMD_LENGTH];
+ const char write_command[SHT3X_CMD_LENGTH];
+};
+
+static const struct sht3x_limit_commands limit_commands[] = {
+ /* temp1_max, humidity1_max */
+ { {0xe1, 0x1f}, {0x61, 0x1d} },
+ /* temp_1_max_hyst, humidity1_max_hyst */
+ { {0xe1, 0x14}, {0x61, 0x16} },
+ /* temp1_min, humidity1_min */
+ { {0xe1, 0x02}, {0x61, 0x00} },
+ /* temp_1_min_hyst, humidity1_min_hyst */
+ { {0xe1, 0x09}, {0x61, 0x0B} },
+};
+
+#define SHT3X_NUM_LIMIT_CMD  ARRAY_SIZE(limit_commands)
+
+static const u16 mode_to_update_interval[] = {
+   0,
+ 2000,
+ 1000,
+ 500,
+ 250,
+ 100,
+};
+
+struct sht3x_data {
+ struct i2c_client *client;
+ struct mutex i2c_lock; /* lock for sending i2c commands */
+ struct mutex data_lock; /* lock for updating driver data */
+
+ u8 mode;
+ const unsigned char *command;
+ u32 wait_time; /* in us*/
+ unsigned long last_update; /* last update in periodic mode*/
+
+ struct sht3x_platform_data setup;
+
+ /*
+ * cached values for temperature and humidity and limits
+ * the limits arrays have the following order:
+ * max, max_hyst, min, min_hyst
+ */
+ int temperature;
+ int temperature_limits[SHT3X_NUM_LIMIT_CMD];
+ u32 humidity;
+ u32 humidity_limits[SHT3X_NUM_LIMIT_CMD];
+};
+
+static u8 get_mode_from_update_interval(u16 value)
+{
+ size_t index;
+ u8 number_of_modes = ARRAY_SIZE(mode_to_update_interval);
+
+ if (value == 0)
+ return 0;
+
+ /* find next faster update interval */
+ for (index = 1; index < number_of_modes; index++) {
+ if (mode_to_update_interval[index] <= value)
+ return index;
+ }
+
+ return number_of_modes - 1;
+}
+
+static int sht3x_read_from_command(struct i2c_client *client,
+   struct sht3x_data *data,
+   const char *command,
+   char *buf, int length, u32 wait_time)
+{
+ int ret;
+
+ mutex_lock(&data->i2c_lock);
+ ret = i2c_master_send(client, command, SHT3X_CMD_LENGTH);
+
+ if (ret != SHT3X_CMD_LENGTH) {
+ ret = ret < 0 ? ret : -EIO;
+ goto out;
+ }
+
+ if (wait_time)
+ usleep_range(wait_time, wait_time + 1000);
+
+ ret = i2c_master_recv(client, buf, length);
+ if (ret != length) {
+ ret = ret < 0 ? ret : -EIO;
+ goto out;
+ }
+
+ ret = 0;
+out:
+ mutex_unlock(&data->i2c_lock);
+ return ret;
+}
+
+static int sht3x_extract_temperature(u16 raw)
+{
+ /*
+ * From datasheet:
+ * T = -45 + 175 * ST / 2^16
+ * Adapted for integer fixed point (3 digit) arithmetic.
+ */
+ return ((21875 * (int)raw) >> 13) - 45000;
+}
+
+static u32 sht3x_extract_humidity(u16 raw)
+{
+ /*
+ * From datasheet:
+ * RH = 100 * SRH / 2^16
+ * Adapted for integer fixed point (3 digit) arithmetic.
+ */
+ return (12500 * (int)raw) >> 13;
+}
+
+static struct sht3x_data *sht3x_update_client(struct device *dev)
+{
+ struct sht3x_data *data = dev_get_drvdata(dev);
+ struct i2c_client *client = data->client;
+ u16 interval_ms = mode_to_update_interval[data->mode];
+ unsigned long interval_jiffies = msecs_to_jiffies(interval_ms);
+ unsigned char buf[SHT3X_RESPONSE_LENGTH];
+ u16 val;
+ int ret;
+
+ /* only update once per interval in periodic mode */
+ if (time_after(jiffies, data->last_update + interval_jiffies)) {
+ ret = sht3x_read_from_command(client, data, data->command, buf,
+      sizeof(buf), data->wait_time);
+ if (ret)
+ return ERR_PTR(ret);
+
+ mutex_lock(&data->data_lock);
+ val = be16_to_cpup((__be16 *)buf);
+ data->temperature = sht3x_extract_temperature(val);
+ val = be16_to_cpup((__be16 *)(buf + 3));
+ data->humidity = sht3x_extract_humidity(val);
+ data->last_update = jiffies;
+ mutex_unlock(&data->data_lock);
+ }
+
+ return data;
+}
+
+/* sysfs attributes */
+static ssize_t temp1_input_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct sht3x_data *data = sht3x_update_client(dev);
+
+ if (IS_ERR(data))
+ return PTR_ERR(data);
+
+ return sprintf(buf, "%d\n", data->temperature);
+}
+
+static ssize_t humidity1_input_show(struct device *dev,
+    struct device_attribute *attr, char *buf)
+{
+ struct sht3x_data *data = sht3x_update_client(dev);
+
+ if (IS_ERR(data))
+ return PTR_ERR(data);
+
+ return sprintf(buf, "%d\n", data->humidity);
+}
+
+static int limits_update(struct sht3x_data *data)
+{
+ int ret;
+ u8 index;
+ int temperature;
+ u32 humidity;
+ u16 raw;
+ char buffer[SHT3X_RESPONSE_LENGTH];
+ const struct sht3x_limit_commands *commands;
+ struct i2c_client *client = data->client;
+
+ for (index = 0; index < SHT3X_NUM_LIMIT_CMD; index++) {
+ commands = &limit_commands[index];
+ ret = sht3x_read_from_command(client, data,
+      commands->read_command, buffer,
+      SHT3X_RESPONSE_LENGTH, 0);
+
+ if (ret)
+ return ret;
+
+ raw = be16_to_cpup((__be16 *)buffer);
+ temperature = sht3x_extract_temperature((raw & 0x01ff) << 7);
+ humidity = sht3x_extract_humidity(raw & 0xfe00);
+ mutex_lock(&data->data_lock);
+ data->temperature_limits[index] = temperature;
+ data->humidity_limits[index] = humidity;
+ mutex_unlock(&data->data_lock);
+ }
+
+ return ret;
+}
+
+static ssize_t temp1_limit_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ int temperature_limit;
+ u8 index;
+ struct sht3x_data *data = dev_get_drvdata(dev);
+
+ index = to_sensor_dev_attr(attr)->index;
+ temperature_limit = data->temperature_limits[index];
+
+ return scnprintf(buf, PAGE_SIZE, "%d\n", temperature_limit);
+}
+
+static ssize_t humidity1_limit_show(struct device *dev,
+    struct device_attribute *attr,
+    char *buf)
+{
+ int humidity_limit;
+ u8 index;
+ struct sht3x_data *data = dev_get_drvdata(dev);
+
+ index = to_sensor_dev_attr(attr)->index;
+ humidity_limit = data->humidity_limits[index];
+
+ return scnprintf(buf, PAGE_SIZE, "%d\n", humidity_limit);
+}
+
+static size_t limit_store(struct device *dev,
+  struct device_attribute *attr,
+  size_t count,
+  int temperature,
+  u32 humidity)
+{
+ char buffer[SHT3X_CMD_LENGTH + SHT3X_WORD_LEN + SHT3X_CRC8_LEN];
+ char *position = buffer;
+ int ret;
+ u16 raw;
+ u8 index;
+ struct sht3x_data *data = dev_get_drvdata(dev);
+ struct i2c_client *client = data->client;
+ const struct sht3x_limit_commands *commands;
+
+ index = to_sensor_dev_attr(attr)->index;
+ commands = &limit_commands[index];
+
+ memcpy(position, commands->write_command, SHT3X_CMD_LENGTH);
+ position += SHT3X_CMD_LENGTH;
+ /*
+ * ST = (T + 45) / 175 * 2^16
+ * SRH = RH / 100 * 2^16
+ * adapted for fixed point arithmetic and packed the same as
+ * in limit_show()
+ */
+ raw = ((u32)(temperature + 45000) * 24543) >> (16 + 7);
+ raw |= ((humidity * 42950) >> 16) & 0xfe00;
+
+ *(__be16 *)(position) = cpu_to_be16(raw);
+ position += SHT3X_WORD_LEN;
+ *position = crc8(sht3x_crc8_table,
+ position - SHT3X_WORD_LEN,
+ SHT3X_WORD_LEN,
+ SHT3X_CRC8_INIT);
+
+ mutex_lock(&data->i2c_lock);
+ ret = i2c_master_send(client, buffer, sizeof(buffer));
+ mutex_unlock(&data->i2c_lock);
+ if (ret != sizeof(buffer)) {
+ ret =  ret < 0 ? ret : -EIO;
+ } else {
+ mutex_lock(&data->data_lock);
+ data->temperature_limits[index] = temperature;
+ data->humidity_limits[index] = humidity;
+ mutex_unlock(&data->data_lock);
+ }
+ ret = count;
+
+ return ret;
+}
+
+static ssize_t temp1_limit_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf,
+ size_t count)
+{
+ int temperature;
+ u32 humidity;
+ u8 index;
+ int ret;
+ struct sht3x_data *data = dev_get_drvdata(dev);
+
+ ret = kstrtoint(buf, 0, &temperature);
+
+ if (ret)
+ return -EINVAL;
+
+ temperature = clamp_val(temperature, -45000, 130000);
+
+ index = to_sensor_dev_attr(attr)->index;
+ humidity = data->humidity_limits[index];
+
+ ret = limit_store(dev, attr, count, temperature, humidity);
+
+ return ret;
+}
+
+static ssize_t humidity1_limit_store(struct device *dev,
+     struct device_attribute *attr,
+     const char *buf,
+     size_t count)
+{
+ int temperature;
+ u32 humidity;
+ u8 index;
+ int ret;
+ struct sht3x_data *data = dev_get_drvdata(dev);
+
+ ret = kstrtou32(buf, 0, &humidity);
+
+ if (ret)
+ return -EINVAL;
+
+ humidity = clamp_val(humidity, 0, 100000);
+ index = to_sensor_dev_attr(attr)->index;
+ temperature = data->temperature_limits[index];
+
+ ret = limit_store(dev, attr, count, temperature, humidity);
+
+ return ret;
+}
+
+static void sht3x_select_command(struct sht3x_data *data)
+{
+ /*
+ * In blocking mode (clock stretching mode) the I2C bus
+ * is blocked for other traffic, thus the call to i2c_master_recv()
+ * will wait until the data is ready. For non blocking mode, we
+ * have to wait ourselves.
+ */
+ if (data->mode > 0) {
+ data->command = sht3x_cmd_measure_periodic_mode;
+ data->wait_time = 0;
+ } else if (data->setup.blocking_io) {
+ data->command = data->setup.high_precision ?
+ sht3x_cmd_measure_blocking_hpm :
+ sht3x_cmd_measure_blocking_lpm;
+ data->wait_time = 0;
+ } else {
+ if (data->setup.high_precision) {
+ data->command = sht3x_cmd_measure_nonblocking_hpm;
+ data->wait_time = SHT3X_NONBLOCKING_WAIT_TIME_HPM;
+ } else {
+ data->command = sht3x_cmd_measure_nonblocking_lpm;
+ data->wait_time = SHT3X_NONBLOCKING_WAIT_TIME_LPM;
+ }
+ }
+}
+
+static int status_register_read(struct device *dev,
+ struct device_attribute *attr,
+ char *buffer, int length)
+{
+ int ret;
+
+ struct sht3x_data *data = dev_get_drvdata(dev);
+ struct i2c_client *client = data->client;
+
+ ret = sht3x_read_from_command(client, data, sht3x_cmd_read_status_reg,
+      buffer, length, 0);
+
+ return ret;
+}
+
+static ssize_t temp1_alarm_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ int ret;
+ int length = SHT3X_WORD_LEN + SHT3X_CRC8_LEN;
+ char buffer[length];
+
+ ret = status_register_read(dev, attr, buffer, length);
+
+ if (ret)
+ return ret;
+
+ return scnprintf(buf, PAGE_SIZE, "%d\n", (buffer[0] & 0x04) == 0x04);
+}
+
+static ssize_t humidity1_alarm_show(struct device *dev,
+    struct device_attribute *attr,
+    char *buf)
+{
+ int ret;
+ int length = SHT3X_WORD_LEN + SHT3X_CRC8_LEN;
+ char buffer[length];
+
+ ret = status_register_read(dev, attr, buffer, length);
+
+ if (ret)
+ return ret;
+
+ return scnprintf(buf, PAGE_SIZE, "%d\n", (buffer[0] & 0x08) == 0x08);
+}
+
+static ssize_t update_interval_show(struct device *dev,
+    struct device_attribute *attr,
+    char *buf)
+{
+ struct sht3x_data *data = dev_get_drvdata(dev);
+
+ return scnprintf(buf, PAGE_SIZE, "%d\n",
+ mode_to_update_interval[data->mode]);
+}
+
+static ssize_t update_interval_store(struct device *dev,
+     struct device_attribute *attr,
+     const char *buf,
+     size_t count)
+{
+ u16 update_interval;
+ u8 mode;
+ int ret;
+ const char *command;
+ struct sht3x_data *data = dev_get_drvdata(dev);
+ struct i2c_client *client = data->client;
+
+ ret = kstrtou16(buf, 0, &update_interval);
+
+ if (ret)
+ return -EINVAL;
+
+ mode = get_mode_from_update_interval(update_interval);
+
+ /* mode did not change */
+ if (mode == data->mode)
+ return count;
+
+ mutex_lock(&data->i2c_lock);
+ mutex_lock(&data->data_lock);
+ /* abort periodic measure */
+ ret = i2c_master_send(client, sht3x_cmd_break, SHT3X_CMD_LENGTH);
+ if (ret != SHT3X_CMD_LENGTH)
+ goto out;
+ data->mode = 0;
+
+ if (mode > 0) {
+ if (data->setup.high_precision)
+ command = periodic_measure_commands_hpm[mode - 1];
+ else
+ command = periodic_measure_commands_lpm[mode - 1];
+
+ /* select mode */
+ ret = i2c_master_send(client, command, SHT3X_CMD_LENGTH);
+ if (ret != SHT3X_CMD_LENGTH)
+ goto out;
+ }
+
+ /* select mode and command */
+ data->mode = mode;
+ sht3x_select_command(data);
+
+out:
+ mutex_unlock(&data->i2c_lock);
+ mutex_unlock(&data->data_lock);
+ if (ret != SHT3X_CMD_LENGTH)
+ return ret < 0 ? ret : -EIO;
+
+ return count;
+}
+
+static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, temp1_input_show, NULL, 0);
+static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO, humidity1_input_show,
+  NULL, 0);
+static SENSOR_DEVICE_ATTR(temp1_max, S_IRUGO | S_IWUSR, temp1_limit_show,
+  temp1_limit_store, 0);
+static SENSOR_DEVICE_ATTR(humidity1_max, S_IRUGO | S_IWUSR,
+  humidity1_limit_show, humidity1_limit_store, 0);
+static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IRUGO | S_IWUSR, temp1_limit_show,
+  temp1_limit_store, 1);
+static SENSOR_DEVICE_ATTR(humidity1_max_hyst, S_IRUGO | S_IWUSR,
+  humidity1_limit_show, humidity1_limit_store, 1);
+static SENSOR_DEVICE_ATTR(temp1_min, S_IRUGO | S_IWUSR, temp1_limit_show,
+  temp1_limit_store, 2);
+static SENSOR_DEVICE_ATTR(humidity1_min, S_IRUGO | S_IWUSR,
+  humidity1_limit_show, humidity1_limit_store, 2);
+static SENSOR_DEVICE_ATTR(temp1_min_hyst, S_IRUGO | S_IWUSR,
+  temp1_limit_show, temp1_limit_store, 3);
+static SENSOR_DEVICE_ATTR(humidity1_min_hyst, S_IRUGO | S_IWUSR,
+  humidity1_limit_show, humidity1_limit_store, 3);
+static SENSOR_DEVICE_ATTR(temp1_alarm, S_IRUGO, temp1_alarm_show, NULL, 3);
+static SENSOR_DEVICE_ATTR(humidity1_alarm, S_IRUGO, humidity1_alarm_show,
+  NULL, 3);
+static SENSOR_DEVICE_ATTR(update_interval, S_IRUGO | S_IWUSR,
+  update_interval_show, update_interval_store, 0);
+
+static struct attribute *sht3x_attrs[] = {
+ &sensor_dev_attr_temp1_input.dev_attr.attr,
+ &sensor_dev_attr_humidity1_input.dev_attr.attr,
+ &sensor_dev_attr_temp1_max.dev_attr.attr,
+ &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
+ &sensor_dev_attr_humidity1_max.dev_attr.attr,
+ &sensor_dev_attr_humidity1_max_hyst.dev_attr.attr,
+ &sensor_dev_attr_temp1_min.dev_attr.attr,
+ &sensor_dev_attr_temp1_min_hyst.dev_attr.attr,
+ &sensor_dev_attr_humidity1_min.dev_attr.attr,
+ &sensor_dev_attr_humidity1_min_hyst.dev_attr.attr,
+ &sensor_dev_attr_temp1_alarm.dev_attr.attr,
+ &sensor_dev_attr_humidity1_alarm.dev_attr.attr,
+ &sensor_dev_attr_update_interval.dev_attr.attr,
+ NULL
+};
+
+static struct attribute *sts3x_attrs[] = {
+ &sensor_dev_attr_temp1_input.dev_attr.attr,
+ NULL
+};
+
+ATTRIBUTE_GROUPS(sht3x);
+ATTRIBUTE_GROUPS(sts3x);
+
+static int sht3x_probe(struct i2c_client *client,
+       const struct i2c_device_id *id)
+{
+ int ret;
+ struct sht3x_data *data;
+ struct device *hwmon_dev;
+ struct i2c_adapter *adap = client->adapter;
+ struct device *dev = &client->dev;
+ const struct attribute_group **attribute_groups;
+
+ /*
+ * we require full i2c support since the sht3x uses multi-byte read and
+ * writes as well as multi-byte commands which are not supported by
+ * the smbus protocol
+ */
+ if (!i2c_check_functionality(adap, I2C_FUNC_I2C))
+ return -ENODEV;
+
+ ret = i2c_master_send(client, sht3x_cmd_clear_status_reg,
+      SHT3X_CMD_LENGTH);
+ if (ret != SHT3X_CMD_LENGTH)
+ return ret < 0 ? ret : -ENODEV;
+
+ data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ data->setup.blocking_io = false;
+ data->setup.high_precision = true;
+ data->mode = 0;
+ data->last_update = 0;
+ data->client = client;
+ crc8_populate_msb(sht3x_crc8_table, SHT3X_CRC8_POLYNOMIAL);
+
+ if (client->dev.platform_data)
+ data->setup = *(struct sht3x_platform_data *)dev->platform_data;
+
+ sht3x_select_command(data);
+
+ mutex_init(&data->i2c_lock);
+ mutex_init(&data->data_lock);
+
+ ret = limits_update(data);
+ if (ret)
+ return ret;
+
+ if (id->driver_data == sts3x)
+ attribute_groups = sts3x_groups;
+ else
+ attribute_groups = sht3x_groups;
+
+ hwmon_dev = devm_hwmon_device_register_with_groups(dev,
+   client->name,
+   data,
+   attribute_groups);
+
+ if (IS_ERR(hwmon_dev))
+ dev_dbg(dev, "unable to register hwmon device\n");
+
+ return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+/* device ID table */
+static const struct i2c_device_id sht3x_ids[] = {
+ {"sht3x", sht3x},
+ {"sts3x", sts3x},
+ {}
+};
+
+MODULE_DEVICE_TABLE(i2c, sht3x_ids);
+
+static struct i2c_driver sht3x_i2c_driver = {
+ .driver.name = "sht3x",
+ .probe       = sht3x_probe,
+ .id_table    = sht3x_ids,
+};
+
+module_i2c_driver(sht3x_i2c_driver);
+
+MODULE_AUTHOR("David Frey <[hidden email]>");
+MODULE_AUTHOR("Pascal Sachs <[hidden email]>");
+MODULE_DESCRIPTION("Sensirion SHT3x humidity and temperature sensor driver");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/platform_data/sht3x.h b/include/linux/platform_data/sht3x.h
new file mode 100644
index 0000000..46af9a0
--- /dev/null
+++ b/include/linux/platform_data/sht3x.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2015 Sensirion AG, Switzerland
+ * Author: David Frey <[hidden email]>
+ * Author: Pascal Sachs <[hidden email]>
+ *
+ * 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.
+ *
+ */
+
+#ifndef __SHT3X_H_
+#define __SHT3X_H_
+
+struct sht3x_platform_data {
+ bool blocking_io;
+ bool high_precision;
+};
+#endif /* __SHT3X_H_ */
--
1.9.1

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