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: Available from the Fintek website
   9   * Fintek F71806F/FG
  10     Prefix: 'f71872f'
  11     Addresses scanned: none, address read from Super I/O config space
  12     Datasheet: Available from the Fintek website
  13   * Fintek F71872F/FG
  14     Prefix: 'f71872f'
  15     Addresses scanned: none, address read from Super I/O config space
  16     Datasheet: Available from the Fintek website
  17
  18 Author: Jean Delvare <jdelvare@suse.de>
  19
  20 Thanks to Denis Kieft from Barracuda Networks for the donation of a
  21 test system (custom Jetway K8M8MS motherboard, with CPU and RAM) and
  22 for providing initial documentation.
  23
  24 Thanks to Kris Chen and Aaron Huang from Fintek for answering technical
  25 questions and providing additional documentation.
  26
  27 Thanks to Chris Lin from Jetway for providing wiring schematics and
  28 answering technical questions.
  29
  30
  31 Description
  32 -----------
  33
  34 The Fintek F71805F/FG Super I/O chip includes complete hardware monitoring
  35 capabilities. It can monitor up to 9 voltages (counting its own power
  36 source), 3 fans and 3 temperature sensors.
  37
  38 This chip also has fan controlling features, using either DC or PWM, in
  39 three different modes (one manual, two automatic).
  40
  41 The Fintek F71872F/FG Super I/O chip is almost the same, with two
  42 additional internal voltages monitored (VSB and battery). It also features
  43 6 VID inputs. The VID inputs are not yet supported by this driver.
  44
  45 The Fintek F71806F/FG Super-I/O chip is essentially the same as the
  46 F71872F/FG, and is undistinguishable therefrom.
  47
  48 The driver assumes that no more than one chip is present, which seems
  49 reasonable.
  50
  51
  52 Voltage Monitoring
  53 ------------------
  54
  55 Voltages are sampled by an 8-bit ADC with a LSB of 8 mV. The supported
  56 range is thus from 0 to 2.040 V. Voltage values outside of this range
  57 need external resistors. An exception is in0, which is used to monitor
  58 the chip's own power source (+3.3V), and is divided internally by a
  59 factor 2. For the F71872F/FG, in9 (VSB) and in10 (battery) are also
  60 divided internally by a factor 2.
  61
  62 The two LSB of the voltage limit registers are not used (always 0), so
  63 you can only set the limits in steps of 32 mV (before scaling).
  64
  65 The wirings and resistor values suggested by Fintek are as follow:
  66
  67         pin                                           expected
  68         name    use           R1      R2     divider  raw val.
  69
  70 in0     VCC     VCC3.3V     int.    int.        2.00    1.65 V
  71 in1     VIN1    VTT1.2V      10K       -        1.00    1.20 V
  72 in2     VIN2    VRAM        100K    100K        2.00   ~1.25 V (1)
  73 in3     VIN3    VCHIPSET     47K    100K        1.47    2.24 V (2)
  74 in4     VIN4    VCC5V       200K     47K        5.25    0.95 V
  75 in5     VIN5    +12V        200K     20K       11.00    1.05 V
  76 in6     VIN6    VCC1.5V      10K       -        1.00    1.50 V
  77 in7     VIN7    VCORE        10K       -        1.00   ~1.40 V (1)
  78 in8     VIN8    VSB5V       200K     47K        1.00    0.95 V
  79 in10    VSB     VSB3.3V     int.    int.        2.00    1.65 V (3)
  80 in9     VBAT    VBATTERY    int.    int.        2.00    1.50 V (3)
  81
  82 (1) Depends on your hardware setup.
  83 (2) Obviously not correct, swapping R1 and R2 would make more sense.
  84 (3) F71872F/FG only.
  85
  86 These values can be used as hints at best, as motherboard manufacturers
  87 are free to use a completely different setup. As a matter of fact, the
  88 Jetway K8M8MS uses a significantly different setup. You will have to
  89 find out documentation about your own motherboard, and edit sensors.conf
  90 accordingly.
  91
  92 Each voltage measured has associated low and high limits, each of which
  93 triggers an alarm when crossed.
  94
  95
  96 Fan Monitoring
  97 --------------
  98
  99 Fan rotation speeds are reported as 12-bit values from a gated clock
 100 signal. Speeds down to 366 RPM can be measured. There is no theoretical
 101 high limit, but values over 6000 RPM seem to cause problem. The effective
 102 resolution is much lower than you would expect, the step between different
 103 register values being 10 rather than 1.
 104
 105 The chip assumes 2 pulse-per-revolution fans.
 106
 107 An alarm is triggered if the rotation speed drops below a programmable
 108 limit or is too low to be measured.
 109
 110
 111 Temperature Monitoring
 112 ----------------------
 113
 114 Temperatures are reported in degrees Celsius. Each temperature measured
 115 has a high limit, those crossing triggers an alarm. There is an associated
 116 hysteresis value, below which the temperature has to drop before the
 117 alarm is cleared.
 118
 119 All temperature channels are external, there is no embedded temperature
 120 sensor. Each channel can be used for connecting either a thermal diode
 121 or a thermistor. The driver reports the currently selected mode, but
 122 doesn't allow changing it. In theory, the BIOS should have configured
 123 everything properly.
 124
 125
 126 Fan Control
 127 -----------
 128
 129 Both PWM (pulse-width modulation) and DC fan speed control methods are
 130 supported. The right one to use depends on external circuitry on the
 131 motherboard, so the driver assumes that the BIOS set the method
 132 properly. The driver will report the method, but won't let you change
 133 it.
 134
 135 When the PWM method is used, you can select the operating frequency,
 136 from 187.5 kHz (default) to 31 Hz. The best frequency depends on the
 137 fan model. As a rule of thumb, lower frequencies seem to give better
 138 control, but may generate annoying high-pitch noise. So a frequency just
 139 above the audible range, such as 25 kHz, may be a good choice; if this
 140 doesn't give you good linear control, try reducing it. Fintek recommends
 141 not going below 1 kHz, as the fan tachometers get confused by lower
 142 frequencies as well.
 143
 144 When the DC method is used, Fintek recommends not going below 5 V, which
 145 corresponds to a pwm value of 106 for the driver. The driver doesn't
 146 enforce this limit though.
 147
 148 Three different fan control modes are supported; the mode number is written
 149 to the pwm<n>_enable file.
 150
 151 * 1: Manual mode
 152   You ask for a specific PWM duty cycle or DC voltage by writing to the
 153   pwm<n> file.
 154
 155 * 2: Temperature mode
 156   You define 3 temperature/fan speed trip points using the
 157   pwm<n>_auto_point<m>_temp and _fan files. These define a staircase
 158   relationship between temperature and fan speed with two additional points
 159   interpolated between the values that you define. When the temperature
 160   is below auto_point1_temp the fan is switched off.
 161
 162 * 3: Fan speed mode
 163   You ask for a specific fan speed by writing to the fan<n>_target file.
 164
 165 Both of the automatic modes require that pwm1 corresponds to fan1, pwm2 to
 166 fan2 and pwm3 to fan3. Temperature mode also requires that temp1 corresponds
 167 to pwm1 and fan1, etc.