hwmon: (w83791d) add support for thermal cruise mode

Add support to set target temperature and tolerance for thermal
cruise mode.

Signed-off-by: Marc Hulsman <m.hulsman@tudelft.nl>
Acked-by: Hans de Goede <j.w.r.degoede@hhs.nl>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/Documentation/hwmon/w83791d b/Documentation/hwmon/w83791d
index b1e4798..5663e49 100644
--- a/Documentation/hwmon/w83791d
+++ b/Documentation/hwmon/w83791d
@@ -77,6 +77,9 @@
 
 Each fan controlled is controlled by PWM. The PWM duty cycle can be read and
 set for each fan separately. Valid values range from 0 (stop) to 255 (full).
+PWM 1-3 support Thermal Cruise mode, in which the PWMs are automatically
+regulated to keep respectively temp 1-3 at a certain target temperature.
+See below for the description of the sysfs-interface.
 
 The w83791d has a global bit used to enable beeping from the speaker when an
 alarm is triggered as well as a bitmask to enable or disable the beep for
@@ -116,9 +119,19 @@
 pwm[1-3]_enable -	this file controls mode of fan/temperature control for
 			fan 1-3. Fan/PWM 4-5 only support manual mode.
 		            * 1 Manual mode
-		            * 2 Thermal Cruise mode   (no further support)
+		            * 2 Thermal Cruise mode
 		            * 3 Fan Speed Cruise mode (no further support)
 
+temp[1-3]_target -	defines the target temperature for Thermal Cruise mode.
+			Unit: millidegree Celsius
+			RW
+
+temp[1-3]_tolerance -	temperature tolerance for Thermal Cruise mode.
+			Specifies an interval around the target temperature
+			in which the fan speed is not changed.
+			Unit: millidegree Celsius
+			RW
+
 Alarms bitmap vs. beep_mask bitmask
 ------------------------------------
 For legacy code using the alarms and beep_mask files:
@@ -146,7 +159,3 @@
 tart3        :  alarms: 0x040000 beep_mask: 0x100000 <== mismatch
 case_open    :  alarms: 0x001000 beep_mask: 0x001000
 global_enable:  alarms: -------- beep_mask: 0x800000 (modified via beep_enable)
-
-W83791D TODO:
----------------
-Provide a patch for Thermal Cruise registers.