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AMC6821 supports configuring if a fan is DC or PWM controlled. Add support for the pwm1_mode attribute to make it runtime configurable. Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
114 lines
3.5 KiB
ReStructuredText
114 lines
3.5 KiB
ReStructuredText
Kernel driver amc6821
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=====================
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Supported chips:
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Texas Instruments AMC6821
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Prefix: 'amc6821'
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Addresses scanned: 0x18, 0x19, 0x1a, 0x2c, 0x2d, 0x2e, 0x4c, 0x4d, 0x4e
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Datasheet: http://focus.ti.com/docs/prod/folders/print/amc6821.html
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Authors:
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Tomaz Mertelj <tomaz.mertelj@guest.arnes.si>
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Description
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-----------
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This driver implements support for the Texas Instruments amc6821 chip.
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The chip has one on-chip and one remote temperature sensor and one pwm fan
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regulator.
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The pwm can be controlled either from software or automatically.
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The driver provides the following sensor accesses in sysfs:
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======================= == ===============================================
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temp1_input ro on-chip temperature
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temp1_min rw "
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temp1_max rw "
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temp1_crit rw "
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temp1_min_alarm ro "
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temp1_max_alarm ro "
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temp1_crit_alarm ro "
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temp2_input ro remote temperature
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temp2_min rw "
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temp2_max rw "
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temp2_crit rw "
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temp2_min_alarm ro "
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temp2_max_alarm ro "
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temp2_crit_alarm ro "
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temp2_fault ro "
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fan1_input ro tachometer speed
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fan1_min rw "
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fan1_max rw "
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fan1_fault ro "
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fan1_pulses rw Pulses per revolution can be either 2 or 4.
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fan1_target rw Target fan speed, to be used with pwm1_enable
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mode 4.
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pwm1 rw pwm1
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pwm1_enable rw regulator mode, 1=open loop, 2=fan controlled
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by remote temperature, 3=fan controlled by
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combination of the on-chip temperature and
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remote-sensor temperature,
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4=fan controlled by target rpm set with
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fan1_target attribute.
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pwm1_mode rw Fan duty control mode (0=DC, 1=PWM)
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pwm1_auto_channels_temp ro 1 if pwm_enable==2, 3 if pwm_enable==3
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pwm1_auto_point1_pwm ro Hardwired to 0, shared for both
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temperature channels.
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pwm1_auto_point2_pwm rw This value is shared for both temperature
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channels.
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pwm1_auto_point3_pwm rw Hardwired to 255, shared for both
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temperature channels.
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temp1_auto_point1_temp ro Hardwired to temp2_auto_point1_temp
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which is rw. Below this temperature fan stops.
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temp1_auto_point2_temp rw The low-temperature limit of the proportional
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range. Below this temperature
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pwm1 = pwm1_auto_point2_pwm. It can go from
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0 degree C to 124 degree C in steps of
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4 degree C. Read it out after writing to get
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the actual value.
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temp1_auto_point3_temp rw Above this temperature fan runs at maximum
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speed. It can go from temp1_auto_point2_temp.
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It can only have certain discrete values
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which depend on temp1_auto_point2_temp and
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pwm1_auto_point2_pwm. Read it out after
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writing to get the actual value.
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temp2_auto_point1_temp rw Must be between 0 degree C and 63 degree C and
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it defines the passive cooling temperature.
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Below this temperature the fan stops in
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the closed loop mode.
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temp2_auto_point2_temp rw The low-temperature limit of the proportional
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range. Below this temperature
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pwm1 = pwm1_auto_point2_pwm. It can go from
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0 degree C to 124 degree C in steps
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of 4 degree C.
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temp2_auto_point3_temp rw Above this temperature fan runs at maximum
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speed. It can only have certain discrete
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values which depend on temp2_auto_point2_temp
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and pwm1_auto_point2_pwm. Read it out after
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writing to get actual value.
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======================= == ===============================================
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Module parameters
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-----------------
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If your board has a BIOS that initializes the amc6821 correctly, you should
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load the module with: init=0.
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If your board BIOS doesn't initialize the chip, or you want
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different settings, you can set the following parameters:
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- init=1,
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- pwminv: 0 default pwm output, 1 inverts pwm output.
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