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Linux/Documentation/hwmon/f71805f.rst

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  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.

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