Kernel driver amc6821

Supported chips:

Texas Instruments AMC6821

Prefix: ‘amc6821’

Addresses scanned: 0x18, 0x19, 0x1a, 0x2c, 0x2d, 0x2e, 0x4c, 0x4d, 0x4e

Datasheet: http://focus.ti.com/docs/prod/folders/print/amc6821.html

Authors:
Tomaz Mertelj <tomaz.mertelj@guest.arnes.si>

Description

This driver implements support for the Texas Instruments amc6821 chip. The chip has one on-chip and one remote temperature sensor and one pwm fan regulator. The pwm can be controlled either from software or automatically.

The driver provides the following sensor accesses in sysfs:

temp1_input ro on-chip temperature
temp1_min rw
temp1_max rw
temp1_crit rw
temp1_min_alarm ro
temp1_max_alarm ro
temp1_crit_alarm ro
temp2_input ro remote temperature
temp2_min rw
temp2_max rw
temp2_crit rw
temp2_min_alarm ro
temp2_max_alarm ro
temp2_crit_alarm ro
temp2_fault ro
fan1_input ro tachometer speed
fan1_min rw
fan1_max rw
fan1_fault ro
fan1_div rw Fan divisor can be either 2 or 4.
pwm1 rw pwm1
pwm1_enable rw regulator mode, 1=open loop, 2=fan controlled by remote temperature, 3=fan controlled by combination of the on-chip temperature and remote-sensor temperature,
pwm1_auto_channels_temp ro 1 if pwm_enable==2, 3 if pwm_enable==3
pwm1_auto_point1_pwm ro Hardwired to 0, shared for both temperature channels.
pwm1_auto_point2_pwm rw This value is shared for both temperature channels.
pwm1_auto_point3_pwm rw Hardwired to 255, shared for both temperature channels.
temp1_auto_point1_temp ro Hardwired to temp2_auto_point1_temp which is rw. Below this temperature fan stops.
temp1_auto_point2_temp rw The low-temperature limit of the proportional range. Below this temperature pwm1 = pwm1_auto_point2_pwm. It can go from 0 degree C to 124 degree C in steps of 4 degree C. Read it out after writing to get the actual value.
temp1_auto_point3_temp rw Above this temperature fan runs at maximum speed. It can go from temp1_auto_point2_temp. It can only have certain discrete values which depend on temp1_auto_point2_temp and pwm1_auto_point2_pwm. Read it out after writing to get the actual value.
temp2_auto_point1_temp rw Must be between 0 degree C and 63 degree C and it defines the passive cooling temperature. Below this temperature the fan stops in the closed loop mode.
temp2_auto_point2_temp rw The low-temperature limit of the proportional range. Below this temperature pwm1 = pwm1_auto_point2_pwm. It can go from 0 degree C to 124 degree C in steps of 4 degree C.
temp2_auto_point3_temp rw Above this temperature fan runs at maximum speed. It can only have certain discrete values which depend on temp2_auto_point2_temp and pwm1_auto_point2_pwm. Read it out after writing to get actual value.

Module parameters

If your board has a BIOS that initializes the amc6821 correctly, you should load the module with: init=0.

If your board BIOS doesn’t initialize the chip, or you want different settings, you can set the following parameters:

  • init=1,
  • pwminv: 0 default pwm output, 1 inverts pwm output.