hwmon: add support for Sensirion SHTC1 sensor

Add support for Sensirion SHTC1 and compatible temperature and humidity
sensors.

Signed-off-by: Tomas Pop <[email protected]>
Signed-off-by: Guenter Roeck <[email protected]>

Documentation/hwmon/shtc1

@@ -0,0 +1,43 @@
+Kernel driver shtc1
+===================
+
+Supported chips:
+  * Sensirion SHTC1
+    Prefix: 'shtc1'
+    Addresses scanned: none
+    Datasheet: http://www.sensirion.com/file/datasheet_shtc1
+
+  * Sensirion SHTW1
+    Prefix: 'shtw1'
+    Addresses scanned: none
+    Datasheet: Not publicly available
+
+Author:
+  Johannes Winkelmann <[email protected]>
+
+Description
+-----------
+
+This driver implements support for the Sensirion SHTC1 chip, a humidity and
+temperature sensor. Temperature is measured in degrees celsius, relative
+humidity is expressed as a percentage. Driver can be used as well for SHTW1
+chip, which has the same electrical interface.
+
+The device communicates with the I2C protocol. All sensors are set to I2C
+address 0x70. See Documentation/i2c/instantiating-devices for methods to
+instantiate the device.
+
+There are two options configurable by means of shtc1_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.
+
+sysfs-Interface
+---------------
+
+temp1_input - temperature input
+humidity1_input - humidity input