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author | Amit Daniel Kachhap <amit.kachhap@linaro.org> | 2011-11-25 15:15:18 +0530 |
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committer | Amit Daniel Kachhap <amit.kachhap@linaro.org> | 2011-12-14 21:27:47 +0530 |
commit | a3cb3d54f43aa6fdae32be9b0e12b66a0ccedfc3 (patch) | |
tree | f2c5aaf722793098bd3eb1fe3be5daa2cb542ab0 /Documentation | |
parent | 0e939cfbb42214337ecd1782c4e233972ed90630 (diff) |
ARM: EXYNOS4: Add tmu hwmon driver
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/hwmon/exynos4_tmu | 81 |
1 files changed, 81 insertions, 0 deletions
diff --git a/Documentation/hwmon/exynos4_tmu b/Documentation/hwmon/exynos4_tmu new file mode 100644 index 00000000000..c3c6b41db60 --- /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 <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 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 |