hwmon: add driver for Microchip TC74

Add hwmon driver for the Microchip TC74.

The TC74 is a single-input 8-bit I2C temperature sensor,
with +-2 degrees centigrade accuracy.

Signed-off-by: Maciej Szmigiero <mail@maciej.szmigiero.name>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
diff --git a/Documentation/hwmon/tc74 b/Documentation/hwmon/tc74
new file mode 100644
index 0000000..43027aa
--- /dev/null
+++ b/Documentation/hwmon/tc74
@@ -0,0 +1,20 @@
+Kernel driver tc74
+====================
+
+Supported chips:
+   * Microchip TC74
+     Prefix: 'tc74'
+     Datasheet: Publicly available at Microchip website.
+
+Description
+-----------
+
+Driver supports the above part.
+
+The tc74 has an 8-bit sensor, with 1 degree centigrade resolution
+and +- 2 degrees centigrade accuracy.
+
+Notes
+-----
+
+Currently entering low power standby mode is not supported.