hwmon: Add Texas Instruments TMP108 temperature sensor driver.

Add support for the TI TMP108 temperature sensor with some device
configuration parameters.
Signed-off-by: John Muir <john@jmuir.com>
[groeck: Initialize of_match_table]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/tmp108

+Kernel driver tmp108
+====================
+
+Supported chips:
+  * Texas Instruments TMP108
+    Prefix: 'tmp108'
+    Addresses scanned: none
+    Datasheet: http://www.ti.com/product/tmp108
+
+Author:
+	John Muir <john@jmuir.com>
+
+Description
+-----------
+
+The Texas Instruments TMP108 implements one temperature sensor. An alert pin
+can be set when temperatures exceed minimum or maximum values plus or minus a
+hysteresis value. (This driver does not support interrupts for the alert pin,
+and the device runs in comparator mode.)
+
+The sensor is accurate to 0.75C over the range of -25 to +85 C, and to 1.0
+degree from -40 to +125 C. Resolution of the sensor is 0.0625 degree. The
+operating temperature has a minimum of -55 C and a maximum of +150 C.
+Hysteresis values can be set to 0, 1, 2, or 4C.
+
+The TMP108 has a programmable update rate that can select between 8, 4, 1, and
+0.5 Hz.
+
+By default the TMP108 reads the temperature continuously. To conserve power,
+the TMP108 has a one-shot mode where the device is normally shut-down. When a
+one shot is requested the temperature is read, the result can be retrieved,
+and then the device is shut down automatically. (This driver only supports
+continuous mode.)
+
+The driver provides the common sysfs-interface for temperatures (see
+Documentation/hwmon/sysfs-interface under Temperatures).

drivers/hwmon/Kconfig

@@ -1602,6 +1602,17 @@ config SENSORS_TMP103
 	  This driver can also be built as a module.  If so, the module
 	  will be called tmp103.
 
+config SENSORS_TMP108
+	tristate "Texas Instruments TMP108"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for Texas Instruments TMP108
+	  sensor chips.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called tmp108.
+
 config SENSORS_TMP401
 	tristate "Texas Instruments TMP401 and compatibles"
 	depends on I2C

drivers/hwmon/Makefile

@@ -153,6 +153,7 @@ obj-$(CONFIG_SENSORS_TC74)	+= tc74.o
 obj-$(CONFIG_SENSORS_THMC50)	+= thmc50.o
 obj-$(CONFIG_SENSORS_TMP102)	+= tmp102.o
 obj-$(CONFIG_SENSORS_TMP103)	+= tmp103.o
+obj-$(CONFIG_SENSORS_TMP108)	+= tmp108.o
 obj-$(CONFIG_SENSORS_TMP401)	+= tmp401.o
 obj-$(CONFIG_SENSORS_TMP421)	+= tmp421.o
 obj-$(CONFIG_SENSORS_TWL4030_MADC)+= twl4030-madc-hwmon.o