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 fanregulator.The pwm can be controlled either from software or automatically.

The driver provides the following sensor accesses in sysfs:

temp1_inputroon-chip temperature
temp1_minrw“
temp1_maxrw“
temp1_critrw“
temp1_min_alarmro“
temp1_max_alarmro“
temp1_crit_alarmro“
temp2_inputroremote temperature
temp2_minrw“
temp2_maxrw“
temp2_critrw“
temp2_min_alarmro“
temp2_max_alarmro“
temp2_crit_alarmro“
temp2_faultro“
fan1_inputrotachometer speed
fan1_minrw“
fan1_maxrw“
fan1_faultro“
fan1_divrwFan divisor can be either 2 or 4.
pwm1rwpwm1
pwm1_enablerwregulator mode, 1=open loop, 2=fan controlledby remote temperature, 3=fan controlled bycombination of the on-chip temperature andremote-sensor temperature,
pwm1_auto_channels_tempro1 if pwm_enable==2, 3 if pwm_enable==3
pwm1_auto_point1_pwmroHardwired to 0, shared for bothtemperature channels.
pwm1_auto_point2_pwmrwThis value is shared for both temperaturechannels.
pwm1_auto_point3_pwmrwHardwired to 255, shared for bothtemperature channels.
temp1_auto_point1_temproHardwired to temp2_auto_point1_tempwhich is rw. Below this temperature fan stops.
temp1_auto_point2_temprwThe low-temperature limit of the proportionalrange. Below this temperaturepwm1 = pwm1_auto_point2_pwm. It can go from0 degree C to 124 degree C in steps of4 degree C. Read it out after writing to getthe actual value.
temp1_auto_point3_temprwAbove this temperature fan runs at maximumspeed. It can go from temp1_auto_point2_temp.It can only have certain discrete valueswhich depend on temp1_auto_point2_temp andpwm1_auto_point2_pwm. Read it out afterwriting to get the actual value.
temp2_auto_point1_temprwMust be between 0 degree C and 63 degree C andit defines the passive cooling temperature.Below this temperature the fan stops inthe closed loop mode.
temp2_auto_point2_temprwThe low-temperature limit of the proportionalrange. Below this temperaturepwm1 = pwm1_auto_point2_pwm. It can go from0 degree C to 124 degree C in stepsof 4 degree C.
temp2_auto_point3_temprwAbove this temperature fan runs at maximumspeed. It can only have certain discretevalues which depend on temp2_auto_point2_tempand pwm1_auto_point2_pwm. Read it out afterwriting to get actual value.

Module parameters

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

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

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