mirror of
https://github.com/torvalds/linux.git
synced 2024-12-20 18:11:47 +00:00
beb70b2d2f
This patch updates the documentation to explain the driver model and file layout. Acked-by: Jonghwa Lee <jonghwa3.lee@samsung.com> Acked-by: Kukjin Kim <kgene.kim@samsung.com> Acked-by: Eduardo Valentin <eduardo.valentin@ti.com> Signed-off-by: Amit Daniel Kachhap <amit.daniel@samsung.com> Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com>
78 lines
2.8 KiB
Plaintext
78 lines
2.8 KiB
Plaintext
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.
|