diff options
Diffstat (limited to 'Documentation/thermal')
| -rw-r--r-- | Documentation/thermal/cpu-cooling-api.txt | 32 | ||||
| -rw-r--r-- | Documentation/thermal/exynos_thermal | 52 | ||||
| -rw-r--r-- | Documentation/thermal/sysfs-api.txt | 9 |
3 files changed, 92 insertions, 1 deletions
diff --git a/Documentation/thermal/cpu-cooling-api.txt b/Documentation/thermal/cpu-cooling-api.txt new file mode 100644 index 000000000000..fca24c931ec8 --- /dev/null +++ b/Documentation/thermal/cpu-cooling-api.txt @@ -0,0 +1,32 @@ +CPU cooling APIs How To +=================================== + +Written by Amit Daniel Kachhap <amit.kachhap@linaro.org> + +Updated: 12 May 2012 + +Copyright (c) 2012 Samsung Electronics Co., Ltd(http://www.samsung.com) + +0. Introduction + +The generic cpu cooling(freq clipping) provides registration/unregistration APIs +to the caller. The binding of the cooling devices to the trip point is left for +the user. The registration APIs returns the cooling device pointer. + +1. cpu cooling APIs + +1.1 cpufreq registration/unregistration APIs +1.1.1 struct thermal_cooling_device *cpufreq_cooling_register( + struct cpumask *clip_cpus) + + This interface function registers the cpufreq cooling device with the name + "thermal-cpufreq-%x". This api can support multiple instances of cpufreq + cooling devices. + + clip_cpus: cpumask of cpus where the frequency constraints will happen. + +1.1.2 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev) + + This interface function unregisters the "thermal-cpufreq-%x" cooling device. + + cdev: Cooling device pointer which has to be unregistered. diff --git a/Documentation/thermal/exynos_thermal b/Documentation/thermal/exynos_thermal new file mode 100644 index 000000000000..2b46f67b1ccb --- /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 <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 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. diff --git a/Documentation/thermal/sysfs-api.txt b/Documentation/thermal/sysfs-api.txt index c087dbcf3535..ca1a1a34970e 100644 --- a/Documentation/thermal/sysfs-api.txt +++ b/Documentation/thermal/sysfs-api.txt @@ -84,7 +84,8 @@ temperature) and throttle appropriate devices. 1.3 interface for binding a thermal zone device with a thermal cooling device 1.3.1 int thermal_zone_bind_cooling_device(struct thermal_zone_device *tz, - int trip, struct thermal_cooling_device *cdev); + int trip, struct thermal_cooling_device *cdev, + unsigned long upper, unsigned long lower); This interface function bind a thermal cooling device to the certain trip point of a thermal zone device. @@ -93,6 +94,12 @@ temperature) and throttle appropriate devices. cdev: thermal cooling device trip: indicates which trip point the cooling devices is associated with in this thermal zone. + upper:the Maximum cooling state for this trip point. + THERMAL_NO_LIMIT means no upper limit, + and the cooling device can be in max_state. + lower:the Minimum cooling state can be used for this trip point. + THERMAL_NO_LIMIT means no lower limit, + and the cooling device can be in cooling state 0. 1.3.2 int thermal_zone_unbind_cooling_device(struct thermal_zone_device *tz, int trip, struct thermal_cooling_device *cdev); |