Based on kernel version 3.6.1. Page generated on 2012-10-11 09:35 EST.
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 49 When an interrupt occurs, this driver notify user space of 50 one of four threshold levels for the interrupt 51 through kobject_uevent_env and sysfs_notify functions. 52 Although an interrupt condition for level_0 can be set, 53 it is not notified to user space through sysfs_notify function. 54 55 Sysfs Interface 56 --------------- 57 name name of the temperature sensor 58 RO 59 60 temp1_input temperature 61 RO 62 63 temp1_max temperature for level_1 interrupt 64 RO 65 66 temp1_crit temperature for level_2 interrupt 67 RO 68 69 temp1_emergency temperature for level_3 interrupt 70 RO 71 72 temp1_max_alarm alarm for level_1 interrupt 73 RO 74 75 temp1_crit_alarm 76 alarm for level_2 interrupt 77 RO 78 79 temp1_emergency_alarm 80 alarm for level_3 interrupt 81 RO