blob: 9010c441696743ec87bec451a71c2b1403c0fa37 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
|
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.
|
