thermal: sysfs: Add a new sysfs node emul_temp for thermal emulation

This patch adds support to set the emulated temperature method in
thermal zone (sensor). After setting this feature thermal zone may
report this temperature and not the actual temperature. The emulation
implementation may be based on sensor capability through platform
specific handler or pure software emulation if no platform handler defined.

This is useful in debugging different temperature threshold and its
associated cooling action. Critical threshold's cannot be emulated.
Writing 0 on this node should disable emulation.

Signed-off-by: Amit Daniel Kachhap <amit.daniel@samsung.com>
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt
index 526d4b90d6c1..6859661c9d31 100644
--- a/Documentation/thermal/sysfs-api.txt
+++ b/Documentation/thermal/sysfs-api.txt
@@ -55,6 +55,8 @@ temperature) and throttle appropriate devices.
         .get_trip_type: get the type of certain trip point.
         .get_trip_temp: get the temperature above which the certain trip point
                         will be fired.
+        .set_emul_temp: set the emulation temperature which helps in debugging
+                        different threshold temperature points.
 
 1.1.2 void thermal_zone_device_unregister(struct thermal_zone_device *tz)
 
@@ -153,6 +155,7 @@ Thermal zone device sys I/F, created once it's registered:
     |---trip_point_[0-*]_temp:  Trip point temperature
     |---trip_point_[0-*]_type:  Trip point type
     |---trip_point_[0-*]_hyst:  Hysteresis value for this trip point
+    |---emul_temp:              Emulated temperature set node
 
 Thermal cooling device sys I/F, created once it's registered:
 /sys/class/thermal/cooling_device[0-*]:
@@ -252,6 +255,16 @@ passive
         Valid values: 0 (disabled) or greater than 1000
         RW, Optional
 
+emul_temp
+        Interface to set the emulated temperature method in thermal zone
+        (sensor). After setting this temperature, the thermal zone may pass
+        this temperature to platform emulation function if registered or
+        cache it locally. This is useful in debugging different temperature
+        threshold and its associated cooling action. This is write only node
+        and writing 0 on this node should disable emulation.
+        Unit: millidegree Celsius
+        WO, Optional
+
 *****************************
 * Cooling device attributes *
 *****************************