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 <jdelvare@suse.de>
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