projects / mirror_ubuntu-bionic-kernel.git / blame
| Commit | Line | Data |
|---|---|---|
| beb70b2d | 1 | Kernel driver exynos_tmu |
| 9d97e5c8 DK |
2 | ================= |
| 3 | ||
| 4 | Supported chips: | |
| beb70b2d | 5 | * ARM SAMSUNG EXYNOS4, EXYNOS5 series of SoC |
| 9d97e5c8 DK |
6 | Datasheet: Not publicly available |
| 7 | ||
| 8 | Authors: Donggeun Kim <dg77.kim@samsung.com> | |
| beb70b2d | 9 | Authors: Amit Daniel <amit.daniel@samsung.com> |
| 9d97e5c8 | 10 | |
| beb70b2d ADK |
11 | TMU controller Description: |
| 12 | --------------------------- | |
| 9d97e5c8 | 13 | |
| beb70b2d | 14 | This driver allows to read temperature inside SAMSUNG EXYNOS4/5 series of SoC. |
| 9d97e5c8 DK |
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 | ||
| beb70b2d | 37 | TMU(Thermal Management Unit) in EXYNOS4/5 generates interrupt |
| 9d97e5c8 | 38 | when temperature exceeds pre-defined levels. |
| beb70b2d | 39 | The maximum number of configurable threshold is five. |
| 9d97e5c8 DK |
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 | 49 | When an interrupt occurs, this driver notify kernel thermal framework |
| beb70b2d | 50 | with the function exynos_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. |
| beb70b2d ADK |
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. |