53 строки
1.7 KiB
Plaintext
53 строки
1.7 KiB
Plaintext
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.
|