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Based on kernel version 3.13. Page generated on 2014-01-20 22:04 EST.

1	Kernel driver exynos_tmu
2	=================
3	
4	Supported chips:
5	* ARM SAMSUNG EXYNOS4, EXYNOS5 series of SoC
6	  Datasheet: Not publicly available
7	
8	Authors: Donggeun Kim <dg77.kim@samsung.com>
9	Authors: Amit Daniel <amit.daniel@samsung.com>
10	
11	TMU controller Description:
12	---------------------------
13	
14	This driver allows to read temperature inside SAMSUNG EXYNOS4/5 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 EXYNOS4/5 generates interrupt
38	when temperature exceeds pre-defined levels.
39	The maximum number of configurable threshold is five.
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	
49	When an interrupt occurs, this driver notify kernel thermal framework
50	with the function exynos_report_trigger.
51	Although an interrupt condition for level_0 can be set,
52	it can be used to synchronize the cooling action.
53	
54	TMU driver description:
55	-----------------------
56	
57	The exynos thermal driver is structured as,
58	
59						Kernel Core thermal framework
60					(thermal_core.c, step_wise.c, cpu_cooling.c)
61									^
62									|
63									|
64	TMU configuration data -------> TMU Driver  <------> Exynos Core thermal wrapper
65	(exynos_tmu_data.c)	      (exynos_tmu.c)	   (exynos_thermal_common.c)
66	(exynos_tmu_data.h)	      (exynos_tmu.h)	   (exynos_thermal_common.h)
67	
68	a) TMU configuration data: This consist of TMU register offsets/bitfields
69			described through structure exynos_tmu_registers. Also several
70			other platform data (struct exynos_tmu_platform_data) members
71			are used to configure the TMU.
72	b) TMU driver: This component initialises the TMU controller and sets different
73			thresholds. It invokes core thermal implementation with the call
74			exynos_report_trigger.
75	c) Exynos Core thermal wrapper: This provides 3 wrapper function to use the
76			Kernel core thermal framework. They are exynos_unregister_thermal,
77			exynos_register_thermal and exynos_report_trigger.
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