hwmon: (tmp401) Add documentation

Documentation for the tmp401 driver.

The documentation describes the tmp401 driver and the supported Texas
Instruments TMP401 and TMP411 temperature sensor chips.

Further documentation for new sysfs attributes supported by this
driver is added to Documentation/hwmon/sysfs-interface.

Signed-off-by: Andre Prendel <andre.prendel@gmx.de>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/Documentation/hwmon/sysfs-interface b/Documentation/hwmon/sysfs-interface
index 004ee16..dcbd502 100644
--- a/Documentation/hwmon/sysfs-interface
+++ b/Documentation/hwmon/sysfs-interface
@@ -70,6 +70,7 @@
 [0-*]	denotes any positive number starting from 0
 [1-*]	denotes any positive number starting from 1
 RO	read only value
+WO	write only value
 RW	read/write value
 
 Read/write values may be read-only for some chips, depending on the
@@ -295,6 +296,24 @@
 		user-space.
 		RO
 
+temp[1-*]_lowest
+		Historical minimum temperature
+		Unit: millidegree Celsius
+		RO
+
+temp[1-*]_highest
+		Historical maximum temperature
+		Unit: millidegree Celsius
+		RO
+
+temp[1-*]_reset_history
+		Reset temp_lowest and temp_highest
+		WO
+
+temp_reset_history
+		Reset temp_lowest and temp_highest for all sensors
+		WO
+
 Some chips measure temperature using external thermistors and an ADC, and
 report the temperature measurement as a voltage. Converting this voltage
 back to a temperature (or the other way around for limits) requires