From c48cbba6fee3587bdfe77ef850a1a0aa30a2a60f Mon Sep 17 00:00:00 2001 From: Amit Daniel Kachhap Date: Thu, 16 Aug 2012 17:11:41 +0530 Subject: 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 Acked-by: Guenter Roeck Cc: SangWook Ju Cc: Durgadoss Cc: Len Brown Cc: Jean Delvare Cc: Kyungmin Park Cc: Kukjin Kim Signed-off-by: Andrew Morton Signed-off-by: Amit Daniel Kachhap Signed-off-by: Zhang Rui --- Documentation/thermal/exynos_thermal | 52 ++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) create mode 100644 Documentation/thermal/exynos_thermal (limited to 'Documentation/thermal') diff --git a/Documentation/thermal/exynos_thermal b/Documentation/thermal/exynos_thermal new file mode 100644 index 00000000000..2b46f67b1cc --- /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 + +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. -- cgit v1.2.3