From 9d97e5c81e15afaef65d00f077f863c94f750839 Mon Sep 17 00:00:00 2001 From: Donggeun Kim Date: Wed, 7 Sep 2011 18:49:08 +0900 Subject: hwmon: Add driver for EXYNOS4 TMU This patch allows to read temperature from TMU(Thermal Management Unit) of SAMSUNG EXYNOS4 series of SoC. Signed-off-by: Donggeun Kim Signed-off-by: MyungJoo Ham Signed-off-by: Kyungmin Park Signed-off-by: Guenter Roeck --- Documentation/hwmon/exynos4_tmu | 81 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 Documentation/hwmon/exynos4_tmu (limited to 'Documentation/hwmon') diff --git a/Documentation/hwmon/exynos4_tmu b/Documentation/hwmon/exynos4_tmu new file mode 100644 index 000000000000..c3c6b41db607 --- /dev/null +++ b/Documentation/hwmon/exynos4_tmu @@ -0,0 +1,81 @@ +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 user space of +one of four threshold levels for the interrupt +through kobject_uevent_env and sysfs_notify functions. +Although an interrupt condition for level_0 can be set, +it is not notified to user space through sysfs_notify function. + +Sysfs Interface +--------------- +name name of the temperature sensor + RO + +temp1_input temperature + RO + +temp1_max temperature for level_1 interrupt + RO + +temp1_crit temperature for level_2 interrupt + RO + +temp1_emergency temperature for level_3 interrupt + RO + +temp1_max_alarm alarm for level_1 interrupt + RO + +temp1_crit_alarm + alarm for level_2 interrupt + RO + +temp1_emergency_alarm + alarm for level_3 interrupt + RO -- cgit v1.2.3