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authorJonghwa Lee2012-11-20 22:31:01 -0600
committerEduardo Valentin2013-03-20 09:26:46 -0500
commit2c2f681e3a4813bd26bc7a8a97a1f0d4962f93cd (patch)
tree381ca6679c8a5527a66fa8986229bb7e7793287d /Documentation
parentee2699b69ac66cb8224958129f27753c67f913e7 (diff)
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Thermal: exynos: Add sysfs node supporting exynos's emulation mode.
This patch supports exynos's emulation mode with newly created sysfs node. 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. This patch includes also documentary placed under Documentation/thermal/. Signed-off-by: Jonghwa Lee <jonghwa3.lee@samsung.com> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Diffstat (limited to 'Documentation')
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1EXYNOS EMULATION MODE
2========================
3
4Copyright (C) 2012 Samsung Electronics
5
6Written by Jonghwa Lee <jonghwa3.lee@samsung.com>
7
8Description
9-----------
10
11Exynos 4x12 (4212, 4412) and 5 series provide emulation mode for thermal management unit.
12Thermal emulation mode supports software debug for TMU's operation. User can set temperature
13manually with software code and TMU will read current temperature from user value not from
14sensor's value.
15
16Enabling CONFIG_EXYNOS_THERMAL_EMUL option will make this support in available.
17When it's enabled, sysfs node will be created under
18/sys/bus/platform/devices/'exynos device name'/ with name of 'emulation'.
19
20The sysfs node, 'emulation', will contain value 0 for the initial state. When you input any
21temperature you want to update to sysfs node, it automatically enable emulation mode and
22current temperature will be changed into it.
23(Exynos also supports user changable delay time which would be used to delay of
24 changing temperature. However, this node only uses same delay of real sensing time, 938us.)
25
26Exynos emulation mode requires synchronous of value changing and enabling. It means when you
27want to update the any value of delay or next temperature, then you have to enable emulation
28mode at the same time. (Or you have to keep the mode enabling.) If you don't, it fails to
29change the value to updated one and just use last succeessful value repeatedly. That's why
30this node gives users the right to change termerpature only. Just one interface makes it more
31simply to use.
32
33Disabling emulation mode only requires writing value 0 to sysfs node.
34
35
36TEMP 120 |
37 |
38 100 |
39 |
40 80 |
41 | +-----------
42 60 | | |
43 | +-------------| |
44 40 | | | |
45 | | | |
46 20 | | | +----------
47 | | | | |
48 0 |______________|_____________|__________|__________|_________
49 A A A A TIME
50 |<----->| |<----->| |<----->| |
51 | 938us | | | | | |
52emulation : 0 50 | 70 | 20 | 0
53current temp : sensor 50 70 20 sensor