Add the rt linux 4.1.3-rt3 as base

[kvmfornfv.git] / kernel / Documentation / thermal / exynos_thermal_emulation

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+EXYNOS EMULATION MODE
+========================
+
+Copyright (C) 2012 Samsung Electronics
+
+Written by Jonghwa Lee <jonghwa3.lee@samsung.com>
+
+Description
+-----------
+
+Exynos 4x12 (4212, 4412) and 5 series provide emulation mode for thermal management unit.
+Thermal emulation mode supports software debug for TMU's operation. User can set temperature
+manually with software code and TMU will read current temperature from user value not from
+sensor's value.
+
+Enabling CONFIG_THERMAL_EMULATION option will make this support available.
+When it's enabled, sysfs node will be created as
+/sys/devices/virtual/thermal/thermal_zone'zone id'/emul_temp.
+
+The sysfs node, 'emul_node', will contain value 0 for the initial state. When you input any
+temperature you want to update to sysfs node, it automatically enable emulation mode and
+current temperature will be changed into it.
+(Exynos also supports user changeable delay time which would be used to delay of
+ changing temperature. However, this node only uses same delay of real sensing time, 938us.)
+
+Exynos emulation mode requires synchronous of value changing and enabling. It means when you
+want to update the any value of delay or next temperature, then you have to enable emulation
+mode at the same time. (Or you have to keep the mode enabling.) If you don't, it fails to
+change the value to updated one and just use last succeessful value repeatedly. That's why
+this node gives users the right to change termerpature only. Just one interface makes it more
+simply to use.
+
+Disabling emulation mode only requires writing value 0 to sysfs node.
+
+
+TEMP   120 |
+           |
+       100 |
+           |
+        80 |
+           |                            +-----------
+        60 |                            |          |
+           |              +-------------|          |
+        40 |              |             |          |
+           |              |             |          |
+        20 |              |             |          +----------
+           |              |             |          |          |
+         0 |______________|_____________|__________|__________|_________
+                  A             A          A                  A     TIME
+                  |<----->|     |<----->|  |<----->|          |
+                  | 938us |     |       |  |       |          |
+emulation    :  0  50     |     70      |  20      |          0
+current temp :   sensor   50            70         20        sensor