Documentation/hwmon/f71805f

   1 Kernel driver f71805f
   2 =====================
   3
   4 Supported chips:
   5   * Fintek F71805F/FG
   6     Prefix: 'f71805f'
   7     Addresses scanned: none, address read from Super I/O config space
   8     Datasheet: Provided by Fintek on request
   9
  10 Author: Jean Delvare <khali@linux-fr.org>
  11
  12 Thanks to Denis Kieft from Barracuda Networks for the donation of a
  13 test system (custom Jetway K8M8MS motherboard, with CPU and RAM) and
  14 for providing initial documentation.
  15
  16 Thanks to Kris Chen and Aaron Huang from Fintek for answering technical
  17 questions and providing additional documentation.
  18
  19 Thanks to Chris Lin from Jetway for providing wiring schematics and
  20 answering technical questions.
  21
  22
  23 Description
  24 -----------
  25
  26 The Fintek F71805F/FG Super I/O chip includes complete hardware monitoring
  27 capabilities. It can monitor up to 9 voltages (counting its own power
  28 source), 3 fans and 3 temperature sensors.
  29
  30 This chip also has fan controlling features, using either DC or PWM, in
  31 three different modes (one manual, two automatic).
  32
  33 The driver assumes that no more than one chip is present, which seems
  34 reasonable.
  35
  36
  37 Voltage Monitoring
  38 ------------------
  39
  40 Voltages are sampled by an 8-bit ADC with a LSB of 8 mV. The supported
  41 range is thus from 0 to 2.040 V. Voltage values outside of this range
  42 need external resistors. An exception is in0, which is used to monitor
  43 the chip's own power source (+3.3V), and is divided internally by a
  44 factor 2.
  45
  46 The two LSB of the voltage limit registers are not used (always 0), so
  47 you can only set the limits in steps of 32 mV (before scaling).
  48
  49 The wirings and resistor values suggested by Fintek are as follow:
  50
  51         pin                                           expected
  52         name    use           R1      R2     divider  raw val.
  53
  54 in0     VCC     VCC3.3V     int.    int.        2.00    1.65 V
  55 in1     VIN1    VTT1.2V      10K       -        1.00    1.20 V
  56 in2     VIN2    VRAM        100K    100K        2.00   ~1.25 V (1)
  57 in3     VIN3    VCHIPSET     47K    100K        1.47    2.24 V (2)
  58 in4     VIN4    VCC5V       200K     47K        5.25    0.95 V
  59 in5     VIN5    +12V        200K     20K       11.00    1.05 V
  60 in6     VIN6    VCC1.5V      10K       -        1.00    1.50 V
  61 in7     VIN7    VCORE        10K       -        1.00   ~1.40 V (1)
  62 in8     VIN8    VSB5V       200K     47K        1.00    0.95 V
  63
  64 (1) Depends on your hardware setup.
  65 (2) Obviously not correct, swapping R1 and R2 would make more sense.
  66
  67 These values can be used as hints at best, as motherboard manufacturers
  68 are free to use a completely different setup. As a matter of fact, the
  69 Jetway K8M8MS uses a significantly different setup. You will have to
  70 find out documentation about your own motherboard, and edit sensors.conf
  71 accordingly.
  72
  73 Each voltage measured has associated low and high limits, each of which
  74 triggers an alarm when crossed.
  75
  76
  77 Fan Monitoring
  78 --------------
  79
  80 Fan rotation speeds are reported as 12-bit values from a gated clock
  81 signal. Speeds down to 366 RPM can be measured. There is no theoretical
  82 high limit, but values over 6000 RPM seem to cause problem. The effective
  83 resolution is much lower than you would expect, the step between different
  84 register values being 10 rather than 1.
  85
  86 The chip assumes 2 pulse-per-revolution fans.
  87
  88 An alarm is triggered if the rotation speed drops below a programmable
  89 limit or is too low to be measured.
  90
  91
  92 Temperature Monitoring
  93 ----------------------
  94
  95 Temperatures are reported in degrees Celsius. Each temperature measured
  96 has a high limit, those crossing triggers an alarm. There is an associated
  97 hysteresis value, below which the temperature has to drop before the
  98 alarm is cleared.
  99
 100 All temperature channels are external, there is no embedded temperature
 101 sensor. Each channel can be used for connecting either a thermal diode
 102 or a thermistor. The driver reports the currently selected mode, but
 103 doesn't allow changing it. In theory, the BIOS should have configured
 104 everything properly.
 105
 106
 107 Fan Control
 108 -----------
 109
 110 Both PWM (pulse-width modulation) and DC fan speed control methods are
 111 supported. The right one to use depends on external circuitry on the
 112 motherboard, so the driver assumes that the BIOS set the method
 113 properly. The driver will report the method, but won't let you change
 114 it.
 115
 116 When the PWM method is used, you can select the operating frequency,
 117 from 187.5 kHz (default) to 31 Hz. The best frequency depends on the
 118 fan model. As a rule of thumb, lower frequencies seem to give better
 119 control, but may generate annoying high-pitch noise. Fintek recommends
 120 not going below 1 kHz, as the fan tachometers get confused by lower
 121 frequencies as well.
 122
 123 When the DC method is used, Fintek recommends not going below 5 V, which
 124 corresponds to a pwm value of 106 for the driver. The driver doesn't
 125 enforce this limit though.
 126
 127 Three different fan control modes are supported:
 128
 129 * Manual mode
 130   You ask for a specific PWM duty cycle or DC voltage.
 131
 132 * Fan speed mode
 133   You ask for a specific fan speed. This mode assumes that pwm1
 134   corresponds to fan1, pwm2 to fan2 and pwm3 to fan3.
 135
 136 * Temperature mode
 137   You define 3 temperature/fan speed trip points, and the fan speed is
 138   adjusted depending on the measured temperature, using interpolation.
 139   This mode is not yet supported by the driver.