linux/Documentation/hwmon/f71805f
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   1Kernel driver f71805f
   2=====================
   3
   4Supported 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
  18Author: Jean Delvare <khali@linux-fr.org>
  19
  20Thanks to Denis Kieft from Barracuda Networks for the donation of a
  21test system (custom Jetway K8M8MS motherboard, with CPU and RAM) and
  22for providing initial documentation.
  23
  24Thanks to Kris Chen and Aaron Huang from Fintek for answering technical
  25questions and providing additional documentation.
  26
  27Thanks to Chris Lin from Jetway for providing wiring schematics and
  28answering technical questions.
  29
  30
  31Description
  32-----------
  33
  34The Fintek F71805F/FG Super I/O chip includes complete hardware monitoring
  35capabilities. It can monitor up to 9 voltages (counting its own power
  36source), 3 fans and 3 temperature sensors.
  37
  38This chip also has fan controlling features, using either DC or PWM, in
  39three different modes (one manual, two automatic).
  40
  41The Fintek F71872F/FG Super I/O chip is almost the same, with two
  42additional internal voltages monitored (VSB and battery). It also features
  436 VID inputs. The VID inputs are not yet supported by this driver.
  44
  45The Fintek F71806F/FG Super-I/O chip is essentially the same as the
  46F71872F/FG, and is undistinguishable therefrom.
  47
  48The driver assumes that no more than one chip is present, which seems
  49reasonable.
  50
  51
  52Voltage Monitoring
  53------------------
  54
  55Voltages are sampled by an 8-bit ADC with a LSB of 8 mV. The supported
  56range is thus from 0 to 2.040 V. Voltage values outside of this range
  57need external resistors. An exception is in0, which is used to monitor
  58the chip's own power source (+3.3V), and is divided internally by a
  59factor 2. For the F71872F/FG, in9 (VSB) and in10 (battery) are also
  60divided internally by a factor 2.
  61
  62The two LSB of the voltage limit registers are not used (always 0), so
  63you can only set the limits in steps of 32 mV (before scaling).
  64
  65The wirings and resistor values suggested by Fintek are as follow:
  66
  67        pin                                           expected
  68        name    use           R1      R2     divider  raw val.
  69
  70in0     VCC     VCC3.3V     int.    int.        2.00    1.65 V
  71in1     VIN1    VTT1.2V      10K       -        1.00    1.20 V
  72in2     VIN2    VRAM        100K    100K        2.00   ~1.25 V (1)
  73in3     VIN3    VCHIPSET     47K    100K        1.47    2.24 V (2)
  74in4     VIN4    VCC5V       200K     47K        5.25    0.95 V
  75in5     VIN5    +12V        200K     20K       11.00    1.05 V
  76in6     VIN6    VCC1.5V      10K       -        1.00    1.50 V
  77in7     VIN7    VCORE        10K       -        1.00   ~1.40 V (1)
  78in8     VIN8    VSB5V       200K     47K        1.00    0.95 V
  79in10    VSB     VSB3.3V     int.    int.        2.00    1.65 V (3)
  80in9     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
  86These values can be used as hints at best, as motherboard manufacturers
  87are free to use a completely different setup. As a matter of fact, the
  88Jetway K8M8MS uses a significantly different setup. You will have to
  89find out documentation about your own motherboard, and edit sensors.conf
  90accordingly.
  91
  92Each voltage measured has associated low and high limits, each of which
  93triggers an alarm when crossed.
  94
  95
  96Fan Monitoring
  97--------------
  98
  99Fan rotation speeds are reported as 12-bit values from a gated clock
 100signal. Speeds down to 366 RPM can be measured. There is no theoretical
 101high limit, but values over 6000 RPM seem to cause problem. The effective
 102resolution is much lower than you would expect, the step between different
 103register values being 10 rather than 1.
 104
 105The chip assumes 2 pulse-per-revolution fans.
 106
 107An alarm is triggered if the rotation speed drops below a programmable
 108limit or is too low to be measured.
 109
 110
 111Temperature Monitoring
 112----------------------
 113
 114Temperatures are reported in degrees Celsius. Each temperature measured
 115has a high limit, those crossing triggers an alarm. There is an associated
 116hysteresis value, below which the temperature has to drop before the
 117alarm is cleared.
 118
 119All temperature channels are external, there is no embedded temperature
 120sensor. Each channel can be used for connecting either a thermal diode
 121or a thermistor. The driver reports the currently selected mode, but
 122doesn't allow changing it. In theory, the BIOS should have configured
 123everything properly.
 124
 125
 126Fan Control
 127-----------
 128
 129Both PWM (pulse-width modulation) and DC fan speed control methods are
 130supported. The right one to use depends on external circuitry on the
 131motherboard, so the driver assumes that the BIOS set the method
 132properly. The driver will report the method, but won't let you change
 133it.
 134
 135When the PWM method is used, you can select the operating frequency,
 136from 187.5 kHz (default) to 31 Hz. The best frequency depends on the
 137fan model. As a rule of thumb, lower frequencies seem to give better
 138control, but may generate annoying high-pitch noise. So a frequency just
 139above the audible range, such as 25 kHz, may be a good choice; if this
 140doesn't give you good linear control, try reducing it. Fintek recommends
 141not going below 1 kHz, as the fan tachometers get confused by lower
 142frequencies as well.
 143
 144When the DC method is used, Fintek recommends not going below 5 V, which
 145corresponds to a pwm value of 106 for the driver. The driver doesn't
 146enforce this limit though.
 147
 148Three different fan control modes are supported; the mode number is written
 149to 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
 165Both of the automatic modes require that pwm1 corresponds to fan1, pwm2 to
 166fan2 and pwm3 to fan3. Temperature mode also requires that temp1 corresponds
 167to pwm1 and fan1, etc.
 168
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