[GitHub/mt8127/android_kernel_alcatel_ttab.git] / Documentation / thermal / exynos_thermal

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.
Commit	Line	Data
9d97e5c8 DK	1	Kernel driver exynos4_tmu
	2	=================
	3
	4	Supported chips:
	5	* ARM SAMSUNG EXYNOS4 series of SoC
	6	Prefix: 'exynos4-tmu'
	7	Datasheet: Not publicly available
	8
	9	Authors: Donggeun Kim <dg77.kim@samsung.com>
	10
	11	Description
	12	-----------
	13
	14	This driver allows to read temperature inside SAMSUNG EXYNOS4 series of SoC.
	15
	16	The chip only exposes the measured 8-bit temperature code value
	17	through a register.
	18	Temperature can be taken from the temperature code.
	19	There are three equations converting from temperature to temperature code.
	20
	21	The three equations are:
	22	1. Two point trimming
	23	Tc = (T - 25) * (TI2 - TI1) / (85 - 25) + TI1
	24
	25	2. One point trimming
	26	Tc = T + TI1 - 25
	27
	28	3. No trimming
	29	Tc = T + 50
	30
	31	Tc: Temperature code, T: Temperature,
	32	TI1: Trimming info for 25 degree Celsius (stored at TRIMINFO register)
	33	Temperature code measured at 25 degree Celsius which is unchanged
	34	TI2: Trimming info for 85 degree Celsius (stored at TRIMINFO register)
	35	Temperature code measured at 85 degree Celsius which is unchanged
	36
	37	TMU(Thermal Management Unit) in EXYNOS4 generates interrupt
	38	when temperature exceeds pre-defined levels.
	39	The maximum number of configurable threshold is four.
	40	The threshold levels are defined as follows:
	41	Level_0: current temperature > trigger_level_0 + threshold
	42	Level_1: current temperature > trigger_level_1 + threshold
	43	Level_2: current temperature > trigger_level_2 + threshold
	44	Level_3: current temperature > trigger_level_3 + threshold
	45
	46	The threshold and each trigger_level are set
	47	through the corresponding registers.
	48
c48cbba6 ADK	49	When an interrupt occurs, this driver notify kernel thermal framework
c48cbba6 ADK	50	with the function exynos4_report_trigger.
9d97e5c8	51	Although an interrupt condition for level_0 can be set,
c48cbba6	52	it can be used to synchronize the cooling action.