| 12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879808182 |
- 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 user space of
- one of four threshold levels for the interrupt
- through kobject_uevent_env and sysfs_notify functions.
- Although an interrupt condition for level_0 can be set,
- it is not notified to user space through sysfs_notify function.
- Sysfs Interface
- ---------------
- name name of the temperature sensor
- RO
- temp1_input temperature
- RO
- temp1_max temperature for level_1 interrupt
- RO
- temp1_crit temperature for level_2 interrupt
- RO
- temp1_emergency temperature for level_3 interrupt
- RO
- temp1_max_alarm alarm for level_1 interrupt
- RO
- temp1_crit_alarm
- alarm for level_2 interrupt
- RO
- temp1_emergency_alarm
- alarm for level_3 interrupt
- RO
|
