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| author | Paolo Bonzini <pbonzini@redhat.com> | 2019-08-09 17:53:39 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2019-08-09 17:53:39 +0300 |
| commit | 0e1c438c44dd9cde56effb44c5f1cfeda72e108d (patch) | |
| tree | fa3492d4d7d8b7444e5d8ebe6c78210826333e4b /Documentation/thermal/exynos_thermal.rst | |
| parent | c096397c78f766db972f923433031f2dec01cae0 (diff) | |
| parent | cdb2d3ee0436d74fa9092f2df46aaa6f9e03c969 (diff) | |
| download | linux-0e1c438c44dd9cde56effb44c5f1cfeda72e108d.tar.xz | |
Merge tag 'kvmarm-fixes-for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD
KVM/arm fixes for 5.3
- A bunch of switch/case fall-through annotation, fixing one actual bug
- Fix PMU reset bug
- Add missing exception class debug strings
Diffstat (limited to 'Documentation/thermal/exynos_thermal.rst')
| -rw-r--r-- | Documentation/thermal/exynos_thermal.rst | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/Documentation/thermal/exynos_thermal.rst b/Documentation/thermal/exynos_thermal.rst new file mode 100644 index 000000000000..5bd556566c70 --- /dev/null +++ b/Documentation/thermal/exynos_thermal.rst @@ -0,0 +1,90 @@ +======================== +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. |