Documentation/hwmon/f71805f.rst

   1 Kernel driver f71805f
   2 =====================
   3
   4 Supported chips:
   5
   6   * Fintek F71805F/FG
   7
   8     Prefix: 'f71805f'
   9
  10     Addresses scanned: none, address read from Super I/O config space
  11
  12     Datasheet: Available from the Fintek website
  13
  14   * Fintek F71806F/FG
  15
  16     Prefix: 'f71872f'
  17
  18     Addresses scanned: none, address read from Super I/O config space
  19
  20     Datasheet: Available from the Fintek website
  21
  22   * Fintek F71872F/FG
  23
  24     Prefix: 'f71872f'
  25
  26     Addresses scanned: none, address read from Super I/O config space
  27
  28     Datasheet: Available from the Fintek website
  29
  30 Author: Jean Delvare <jdelvare@suse.de>
  31
  32 Thanks to Denis Kieft from Barracuda Networks for the donation of a
  33 test system (custom Jetway K8M8MS motherboard, with CPU and RAM) and
  34 for providing initial documentation.
  35
  36 Thanks to Kris Chen and Aaron Huang from Fintek for answering technical
  37 questions and providing additional documentation.
  38
  39 Thanks to Chris Lin from Jetway for providing wiring schematics and
  40 answering technical questions.
  41
  42
  43 Description
  44 -----------
  45
  46 The Fintek F71805F/FG Super I/O chip includes complete hardware monitoring
  47 capabilities. It can monitor up to 9 voltages (counting its own power
  48 source), 3 fans and 3 temperature sensors.
  49
  50 This chip also has fan controlling features, using either DC or PWM, in
  51 three different modes (one manual, two automatic).
  52
  53 The Fintek F71872F/FG Super I/O chip is almost the same, with two
  54 additional internal voltages monitored (VSB and battery). It also features
  55 6 VID inputs. The VID inputs are not yet supported by this driver.
  56
  57 The Fintek F71806F/FG Super-I/O chip is essentially the same as the
  58 F71872F/FG, and is undistinguishable therefrom.
  59
  60 The driver assumes that no more than one chip is present, which seems
  61 reasonable.
  62
  63
  64 Voltage Monitoring
  65 ------------------
  66
  67 Voltages are sampled by an 8-bit ADC with a LSB of 8 mV. The supported
  68 range is thus from 0 to 2.040 V. Voltage values outside of this range
  69 need external resistors. An exception is in0, which is used to monitor
  70 the chip's own power source (+3.3V), and is divided internally by a
  71 factor 2. For the F71872F/FG, in9 (VSB) and in10 (battery) are also
  72 divided internally by a factor 2.
  73
  74 The two LSB of the voltage limit registers are not used (always 0), so
  75 you can only set the limits in steps of 32 mV (before scaling).
  76
  77 The wirings and resistor values suggested by Fintek are as follow:
  78
  79 ======= ======= =========== ==== ======= ============ ==============
  80 in      pin                                           expected
  81         name    use           R1      R2     divider  raw val.
  82 ======= ======= =========== ==== ======= ============ ==============
  83 in0     VCC     VCC3.3V     int.    int.        2.00    1.65 V
  84 in1     VIN1    VTT1.2V      10K       -        1.00    1.20 V
  85 in2     VIN2    VRAM        100K    100K        2.00   ~1.25 V [1]_
  86 in3     VIN3    VCHIPSET     47K    100K        1.47    2.24 V [2]_
  87 in4     VIN4    VCC5V       200K     47K        5.25    0.95 V
  88 in5     VIN5    +12V        200K     20K       11.00    1.05 V
  89 in6     VIN6    VCC1.5V      10K       -        1.00    1.50 V
  90 in7     VIN7    VCORE        10K       -        1.00   ~1.40 V [1]_
  91 in8     VIN8    VSB5V       200K     47K        1.00    0.95 V
  92 in10    VSB     VSB3.3V     int.    int.        2.00    1.65 V [3]_
  93 in9     VBAT    VBATTERY    int.    int.        2.00    1.50 V [3]_
  94 ======= ======= =========== ==== ======= ============ ==============
  95
  96 .. [1] Depends on your hardware setup.
  97 .. [2] Obviously not correct, swapping R1 and R2 would make more sense.
  98 .. [3] F71872F/FG only.
  99
 100 These values can be used as hints at best, as motherboard manufacturers
 101 are free to use a completely different setup. As a matter of fact, the
 102 Jetway K8M8MS uses a significantly different setup. You will have to
 103 find out documentation about your own motherboard, and edit sensors.conf
 104 accordingly.
 105
 106 Each voltage measured has associated low and high limits, each of which
 107 triggers an alarm when crossed.
 108
 109
 110 Fan Monitoring
 111 --------------
 112
 113 Fan rotation speeds are reported as 12-bit values from a gated clock
 114 signal. Speeds down to 366 RPM can be measured. There is no theoretical
 115 high limit, but values over 6000 RPM seem to cause problem. The effective
 116 resolution is much lower than you would expect, the step between different
 117 register values being 10 rather than 1.
 118
 119 The chip assumes 2 pulse-per-revolution fans.
 120
 121 An alarm is triggered if the rotation speed drops below a programmable
 122 limit or is too low to be measured.
 123
 124
 125 Temperature Monitoring
 126 ----------------------
 127
 128 Temperatures are reported in degrees Celsius. Each temperature measured
 129 has a high limit, those crossing triggers an alarm. There is an associated
 130 hysteresis value, below which the temperature has to drop before the
 131 alarm is cleared.
 132
 133 All temperature channels are external, there is no embedded temperature
 134 sensor. Each channel can be used for connecting either a thermal diode
 135 or a thermistor. The driver reports the currently selected mode, but
 136 doesn't allow changing it. In theory, the BIOS should have configured
 137 everything properly.
 138
 139
 140 Fan Control
 141 -----------
 142
 143 Both PWM (pulse-width modulation) and DC fan speed control methods are
 144 supported. The right one to use depends on external circuitry on the
 145 motherboard, so the driver assumes that the BIOS set the method
 146 properly. The driver will report the method, but won't let you change
 147 it.
 148
 149 When the PWM method is used, you can select the operating frequency,
 150 from 187.5 kHz (default) to 31 Hz. The best frequency depends on the
 151 fan model. As a rule of thumb, lower frequencies seem to give better
 152 control, but may generate annoying high-pitch noise. So a frequency just
 153 above the audible range, such as 25 kHz, may be a good choice; if this
 154 doesn't give you good linear control, try reducing it. Fintek recommends
 155 not going below 1 kHz, as the fan tachometers get confused by lower
 156 frequencies as well.
 157
 158 When the DC method is used, Fintek recommends not going below 5 V, which
 159 corresponds to a pwm value of 106 for the driver. The driver doesn't
 160 enforce this limit though.
 161
 162 Three different fan control modes are supported; the mode number is written
 163 to the pwm<n>_enable file.
 164
 165 * 1: Manual mode
 166   You ask for a specific PWM duty cycle or DC voltage by writing to the
 167   pwm<n> file.
 168
 169 * 2: Temperature mode
 170   You define 3 temperature/fan speed trip points using the
 171   pwm<n>_auto_point<m>_temp and _fan files. These define a staircase
 172   relationship between temperature and fan speed with two additional points
 173   interpolated between the values that you define. When the temperature
 174   is below auto_point1_temp the fan is switched off.
 175
 176 * 3: Fan speed mode
 177   You ask for a specific fan speed by writing to the fan<n>_target file.
 178
 179 Both of the automatic modes require that pwm1 corresponds to fan1, pwm2 to
 180 fan2 and pwm3 to fan3. Temperature mode also requires that temp1 corresponds
 181 to pwm1 and fan1, etc.