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| author | Amit Daniel Kachhap <amit.kachhap@linaro.org> | 2012-08-16 17:11:41 +0530 |
|---|---|---|
| committer | Zhang Rui <rui.zhang@intel.com> | 2012-09-24 14:44:38 +0800 |
| commit | c48cbba6fee3587bdfe77ef850a1a0aa30a2a60f (patch) | |
| tree | 43a342f501ce99e0b44b5a9346dd3edcf1b255d9 /Documentation/thermal | |
| parent | 023614183768a7ac62898bded5ec6c0c9fecbdd9 (diff) | |
| download | kernel-common-c48cbba6fee3587bdfe77ef850a1a0aa30a2a60f.tar.gz kernel-common-c48cbba6fee3587bdfe77ef850a1a0aa30a2a60f.tar.bz2 kernel-common-c48cbba6fee3587bdfe77ef850a1a0aa30a2a60f.zip | |
hwmon: exynos4: move thermal sensor driver to driver/thermal directory
This movement is needed because the hwmon entries and corresponding sysfs
interface is a duplicate of utilities already provided by
driver/thermal/thermal_sys.c. The goal is to place it in thermal folder
and add necessary functions to use the in-kernel thermal interfaces.
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org>
Acked-by: Guenter Roeck <guenter.roeck@ericsson.com>
Cc: SangWook Ju <sw.ju@samsung.com>
Cc: Durgadoss <durgadoss.r@intel.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Kyungmin Park <kmpark@infradead.org>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Amit Daniel Kachhap <amit.daniel@samsung.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Diffstat (limited to 'Documentation/thermal')
| -rw-r--r-- | Documentation/thermal/exynos_thermal | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/Documentation/thermal/exynos_thermal b/Documentation/thermal/exynos_thermal new file mode 100644 index 000000000000..2b46f67b1ccb --- /dev/null +++ b/Documentation/thermal/exynos_thermal @@ -0,0 +1,52 @@ +Kernel driver exynos4_tmu +================= + +Supported chips: +* ARM SAMSUNG EXYNOS4 series of SoC + Prefix: 'exynos4-tmu' + Datasheet: Not publicly available + +Authors: Donggeun Kim <dg77.kim@samsung.com> + +Description +----------- + +This driver allows to read temperature inside SAMSUNG EXYNOS4 series of SoC. + +The chip only exposes the measured 8-bit temperature code value +through a register. +Temperature can be taken from the temperature code. +There are three equations converting from temperature to temperature code. + +The three equations are: + 1. Two point trimming + Tc = (T - 25) * (TI2 - TI1) / (85 - 25) + TI1 + + 2. One point trimming + Tc = T + TI1 - 25 + + 3. No trimming + Tc = T + 50 + + Tc: Temperature code, T: Temperature, + TI1: Trimming info for 25 degree Celsius (stored at TRIMINFO register) + Temperature code measured at 25 degree Celsius which is unchanged + TI2: Trimming info for 85 degree Celsius (stored at TRIMINFO register) + Temperature code measured at 85 degree Celsius which is unchanged + +TMU(Thermal Management Unit) in EXYNOS4 generates interrupt +when temperature exceeds pre-defined levels. +The maximum number of configurable threshold is four. +The threshold levels are defined as follows: + Level_0: current temperature > trigger_level_0 + threshold + Level_1: current temperature > trigger_level_1 + threshold + Level_2: current temperature > trigger_level_2 + threshold + Level_3: current temperature > trigger_level_3 + threshold + + The threshold and each trigger_level are set + through the corresponding registers. + +When an interrupt occurs, this driver notify kernel thermal framework +with the function exynos4_report_trigger. +Although an interrupt condition for level_0 can be set, +it can be used to synchronize the cooling action. |