Documentation/hwmon/amc6821.rst

   1 Kernel driver amc6821
   2 =====================
   3
   4 Supported chips:
   5
   6         Texas Instruments AMC6821
   7
   8         Prefix: 'amc6821'
   9
  10         Addresses scanned: 0x18, 0x19, 0x1a, 0x2c, 0x2d, 0x2e, 0x4c, 0x4d, 0x4e
  11
  12         Datasheet: http://focus.ti.com/docs/prod/folders/print/amc6821.html
  13
  14 Authors:
  15         Tomaz Mertelj <tomaz.mertelj@guest.arnes.si>
  16
  17
  18 Description
  19 -----------
  20
  21 This driver implements support for the Texas Instruments amc6821 chip.
  22 The chip has one on-chip and one remote temperature sensor and one pwm fan
  23 regulator.
  24 The pwm can be controlled either from software or automatically.
  25
  26 The driver provides the following sensor accesses in sysfs:
  27
  28 ======================= ==      ===============================================
  29 temp1_input             ro      on-chip temperature
  30 temp1_min               rw      "
  31 temp1_max               rw      "
  32 temp1_crit              rw      "
  33 temp1_min_alarm         ro      "
  34 temp1_max_alarm         ro      "
  35 temp1_crit_alarm        ro      "
  36
  37 temp2_input             ro      remote temperature
  38 temp2_min               rw      "
  39 temp2_max               rw      "
  40 temp2_crit              rw      "
  41 temp2_min_alarm         ro      "
  42 temp2_max_alarm         ro      "
  43 temp2_crit_alarm        ro      "
  44 temp2_fault             ro      "
  45
  46 fan1_input              ro      tachometer speed
  47 fan1_min                rw      "
  48 fan1_max                rw      "
  49 fan1_fault              ro      "
  50 fan1_pulses             rw      Pulses per revolution can be either 2 or 4.
  51 fan1_target             rw      Target fan speed, to be used with pwm1_enable
  52                                 mode 4.
  53
  54 pwm1                    rw      pwm1
  55 pwm1_enable             rw      regulator mode, 1=open loop, 2=fan controlled
  56                                 by remote temperature, 3=fan controlled by
  57                                 combination of the on-chip temperature and
  58                                 remote-sensor temperature,
  59                                 4=fan controlled by target rpm set with
  60                                 fan1_target attribute.
  61 pwm1_mode               rw      Fan duty control mode (0=DC, 1=PWM)
  62 pwm1_auto_channels_temp ro      1 if pwm_enable==2, 3 if pwm_enable==3
  63 pwm1_auto_point1_pwm    ro      Hardwired to 0, shared for both
  64                                 temperature channels.
  65 pwm1_auto_point2_pwm    rw      This value is shared for both temperature
  66                                 channels.
  67 pwm1_auto_point3_pwm    rw      Hardwired to 255, shared for both
  68                                 temperature channels.
  69
  70 temp1_auto_point1_temp  ro      Hardwired to temp2_auto_point1_temp
  71                                 which is rw. Below this temperature fan stops.
  72 temp1_auto_point2_temp  rw      The low-temperature limit of the proportional
  73                                 range. Below this temperature
  74                                 pwm1 = pwm1_auto_point2_pwm. It can go from
  75                                 0 degree C to 124 degree C in steps of
  76                                 4 degree C. Read it out after writing to get
  77                                 the actual value.
  78 temp1_auto_point3_temp  rw      Above this temperature fan runs at maximum
  79                                 speed. It can go from temp1_auto_point2_temp.
  80                                 It can only have certain discrete values
  81                                 which depend on temp1_auto_point2_temp and
  82                                 pwm1_auto_point2_pwm. Read it out after
  83                                 writing to get the actual value.
  84
  85 temp2_auto_point1_temp  rw      Must be between 0 degree C and 63 degree C and
  86                                 it defines the passive cooling temperature.
  87                                 Below this temperature the fan stops in
  88                                 the closed loop mode.
  89 temp2_auto_point2_temp  rw      The low-temperature limit of the proportional
  90                                 range. Below this temperature
  91                                 pwm1 = pwm1_auto_point2_pwm. It can go from
  92                                 0 degree C to 124 degree C in steps
  93                                 of 4 degree C.
  94
  95 temp2_auto_point3_temp  rw      Above this temperature fan runs at maximum
  96                                 speed. It can only have certain discrete
  97                                 values which depend on temp2_auto_point2_temp
  98                                 and pwm1_auto_point2_pwm. Read it out after
  99                                 writing to get actual value.
 100 ======================= ==      ===============================================
 101
 102
 103 Module parameters
 104 -----------------
 105
 106 If your board has a BIOS that initializes the amc6821 correctly, you should
 107 load the module with: init=0.
 108
 109 If your board BIOS doesn't initialize the chip, or you want
 110 different settings, you can set the following parameters:
 111
 112 - init=1,
 113 - pwminv: 0 default pwm output, 1 inverts pwm output.