xref: /linux/Documentation/hwmon/f71805f.rst (revision d99ff463ecf651437e9e4abe68f331dfb6b5bd9d)
1Kernel driver f71805f
2=====================
3
4Supported 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
30Author: Jean Delvare <jdelvare@suse.de>
31
32Thanks to Denis Kieft from Barracuda Networks for the donation of a
33test system (custom Jetway K8M8MS motherboard, with CPU and RAM) and
34for providing initial documentation.
35
36Thanks to Kris Chen and Aaron Huang from Fintek for answering technical
37questions and providing additional documentation.
38
39Thanks to Chris Lin from Jetway for providing wiring schematics and
40answering technical questions.
41
42
43Description
44-----------
45
46The Fintek F71805F/FG Super I/O chip includes complete hardware monitoring
47capabilities. It can monitor up to 9 voltages (counting its own power
48source), 3 fans and 3 temperature sensors.
49
50This chip also has fan controlling features, using either DC or PWM, in
51three different modes (one manual, two automatic).
52
53The Fintek F71872F/FG Super I/O chip is almost the same, with two
54additional internal voltages monitored (VSB and battery). It also features
556 VID inputs. The VID inputs are not yet supported by this driver.
56
57The Fintek F71806F/FG Super-I/O chip is essentially the same as the
58F71872F/FG, and is undistinguishable therefrom.
59
60The driver assumes that no more than one chip is present, which seems
61reasonable.
62
63
64Voltage Monitoring
65------------------
66
67Voltages are sampled by an 8-bit ADC with a LSB of 8 mV. The supported
68range is thus from 0 to 2.040 V. Voltage values outside of this range
69need external resistors. An exception is in0, which is used to monitor
70the chip's own power source (+3.3V), and is divided internally by a
71factor 2. For the F71872F/FG, in9 (VSB) and in10 (battery) are also
72divided internally by a factor 2.
73
74The two LSB of the voltage limit registers are not used (always 0), so
75you can only set the limits in steps of 32 mV (before scaling).
76
77The wirings and resistor values suggested by Fintek are as follow:
78
79======= ======= =========== ==== ======= ============ ==============
80in      pin                                           expected
81	name    use           R1      R2     divider  raw val.
82======= ======= =========== ==== ======= ============ ==============
83in0     VCC     VCC3.3V     int.    int.        2.00    1.65 V
84in1     VIN1    VTT1.2V      10K       -        1.00    1.20 V
85in2     VIN2    VRAM        100K    100K        2.00   ~1.25 V [1]_
86in3     VIN3    VCHIPSET     47K    100K        1.47    2.24 V [2]_
87in4     VIN4    VCC5V       200K     47K        5.25    0.95 V
88in5     VIN5    +12V        200K     20K       11.00    1.05 V
89in6     VIN6    VCC1.5V      10K       -        1.00    1.50 V
90in7     VIN7    VCORE        10K       -        1.00   ~1.40 V [1]_
91in8     VIN8    VSB5V       200K     47K        1.00    0.95 V
92in10    VSB     VSB3.3V     int.    int.        2.00    1.65 V [3]_
93in9     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
100These values can be used as hints at best, as motherboard manufacturers
101are free to use a completely different setup. As a matter of fact, the
102Jetway K8M8MS uses a significantly different setup. You will have to
103find out documentation about your own motherboard, and edit sensors.conf
104accordingly.
105
106Each voltage measured has associated low and high limits, each of which
107triggers an alarm when crossed.
108
109
110Fan Monitoring
111--------------
112
113Fan rotation speeds are reported as 12-bit values from a gated clock
114signal. Speeds down to 366 RPM can be measured. There is no theoretical
115high limit, but values over 6000 RPM seem to cause problem. The effective
116resolution is much lower than you would expect, the step between different
117register values being 10 rather than 1.
118
119The chip assumes 2 pulse-per-revolution fans.
120
121An alarm is triggered if the rotation speed drops below a programmable
122limit or is too low to be measured.
123
124
125Temperature Monitoring
126----------------------
127
128Temperatures are reported in degrees Celsius. Each temperature measured
129has a high limit, those crossing triggers an alarm. There is an associated
130hysteresis value, below which the temperature has to drop before the
131alarm is cleared.
132
133All temperature channels are external, there is no embedded temperature
134sensor. Each channel can be used for connecting either a thermal diode
135or a thermistor. The driver reports the currently selected mode, but
136doesn't allow changing it. In theory, the BIOS should have configured
137everything properly.
138
139
140Fan Control
141-----------
142
143Both PWM (pulse-width modulation) and DC fan speed control methods are
144supported. The right one to use depends on external circuitry on the
145motherboard, so the driver assumes that the BIOS set the method
146properly. The driver will report the method, but won't let you change
147it.
148
149When the PWM method is used, you can select the operating frequency,
150from 187.5 kHz (default) to 31 Hz. The best frequency depends on the
151fan model. As a rule of thumb, lower frequencies seem to give better
152control, but may generate annoying high-pitch noise. So a frequency just
153above the audible range, such as 25 kHz, may be a good choice; if this
154doesn't give you good linear control, try reducing it. Fintek recommends
155not going below 1 kHz, as the fan tachometers get confused by lower
156frequencies as well.
157
158When the DC method is used, Fintek recommends not going below 5 V, which
159corresponds to a pwm value of 106 for the driver. The driver doesn't
160enforce this limit though.
161
162Three different fan control modes are supported; the mode number is written
163to 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
179Both of the automatic modes require that pwm1 corresponds to fan1, pwm2 to
180fan2 and pwm3 to fan3. Temperature mode also requires that temp1 corresponds
181to pwm1 and fan1, etc.
182