drm/rockchip: dw_hdmi_qp: Simplify clock handling
[drm/drm-misc.git] / Documentation / hwmon / amc6821.rst
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1 Kernel driver amc6821
2 =====================
4 Supported chips:
6         Texas Instruments AMC6821
8         Prefix: 'amc6821'
10         Addresses scanned: 0x18, 0x19, 0x1a, 0x2c, 0x2d, 0x2e, 0x4c, 0x4d, 0x4e
12         Datasheet: http://focus.ti.com/docs/prod/folders/print/amc6821.html
14 Authors:
15         Tomaz Mertelj <tomaz.mertelj@guest.arnes.si>
18 Description
19 -----------
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.
26 The driver provides the following sensor accesses in sysfs:
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      "
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      "
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.
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.
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.
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.
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 ======================= ==      ===============================================
103 Module parameters
104 -----------------
106 If your board has a BIOS that initializes the amc6821 correctly, you should
107 load the module with: init=0.
109 If your board BIOS doesn't initialize the chip, or you want
110 different settings, you can set the following parameters:
112 - init=1,
113 - pwminv: 0 default pwm output, 1 inverts pwm output.