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| -rw-r--r-- | Documentation/thermal/exynos_thermal | 77 | ||||
| -rw-r--r-- | Documentation/thermal/exynos_thermal_emulation | 53 |
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diff --git a/Documentation/thermal/exynos_thermal b/Documentation/thermal/exynos_thermal new file mode 100644 index 000000000..9010c4416 --- /dev/null +++ b/Documentation/thermal/exynos_thermal @@ -0,0 +1,77 @@ +Kernel driver exynos_tmu +================= + +Supported chips: +* ARM SAMSUNG EXYNOS4, EXYNOS5 series of SoC + Datasheet: Not publicly available + +Authors: Donggeun Kim <dg77.kim@samsung.com> +Authors: Amit Daniel <amit.daniel@samsung.com> + +TMU controller Description: +--------------------------- + +This driver allows to read temperature inside SAMSUNG EXYNOS4/5 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 EXYNOS4/5 generates interrupt +when temperature exceeds pre-defined levels. +The maximum number of configurable threshold is five. +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 exynos_report_trigger. +Although an interrupt condition for level_0 can be set, +it can be used to synchronize the cooling action. + +TMU driver description: +----------------------- + +The exynos thermal driver is structured as, + + Kernel Core thermal framework + (thermal_core.c, step_wise.c, cpu_cooling.c) + ^ + | + | +TMU configuration data -------> TMU Driver <------> Exynos Core thermal wrapper +(exynos_tmu_data.c) (exynos_tmu.c) (exynos_thermal_common.c) +(exynos_tmu_data.h) (exynos_tmu.h) (exynos_thermal_common.h) + +a) TMU configuration data: This consist of TMU register offsets/bitfields + described through structure exynos_tmu_registers. Also several + other platform data (struct exynos_tmu_platform_data) members + are used to configure the TMU. +b) TMU driver: This component initialises the TMU controller and sets different + thresholds. It invokes core thermal implementation with the call + exynos_report_trigger. +c) Exynos Core thermal wrapper: This provides 3 wrapper function to use the + Kernel core thermal framework. They are exynos_unregister_thermal, + exynos_register_thermal and exynos_report_trigger. diff --git a/Documentation/thermal/exynos_thermal_emulation b/Documentation/thermal/exynos_thermal_emulation new file mode 100644 index 000000000..b15efec6c --- /dev/null +++ b/Documentation/thermal/exynos_thermal_emulation @@ -0,0 +1,53 @@ +EXYNOS EMULATION MODE +======================== + +Copyright (C) 2012 Samsung Electronics + +Written by Jonghwa Lee <jonghwa3.lee@samsung.com> + +Description +----------- + +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. + +Enabling CONFIG_THERMAL_EMULATION option will make this support available. +When it's enabled, sysfs node will be created as +/sys/devices/virtual/thermal/thermal_zone'zone id'/emul_temp. + +The sysfs node, 'emul_node', will contain value 0 for the initial state. When you input any +temperature you want to update to sysfs node, it automatically enable emulation mode and +current temperature will be changed into it. +(Exynos also supports user changeable delay time which would be used to delay of + changing temperature. However, this node only uses same delay of real sensing time, 938us.) + +Exynos emulation mode requires synchronous of value changing and enabling. It means when you +want to update the any value of delay or next temperature, then you have to enable emulation +mode at the same time. (Or you have to keep the mode enabling.) If you don't, it fails to +change the value to updated one and just use last succeessful value repeatedly. That's why +this node gives users the right to change termerpature only. Just one interface makes it more +simply to use. + +Disabling emulation mode only requires writing value 0 to sysfs node. + + +TEMP 120 | + | + 100 | + | + 80 | + | +----------- + 60 | | | + | +-------------| | + 40 | | | | + | | | | + 20 | | | +---------- + | | | | | + 0 |______________|_____________|__________|__________|_________ + A A A A TIME + |<----->| |<----->| |<----->| | + | 938us | | | | | | +emulation : 0 50 | 70 | 20 | 0 +current temp : sensor 50 70 20 sensor |