tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1Kernel driver w83627ehf
2=======================
3
4Supported chips:
5 * Winbond W83627EHF/EHG/DHG (ISA access ONLY)
6 Prefix: 'w83627ehf'
7 Addresses scanned: ISA address retrieved from Super I/O registers
8 Datasheet:
9 http://www.winbond-usa.com/products/winbond_products/pdfs/PCIC/W83627EHF_%20W83627EHGb.pdf
10 DHG datasheet confidential.
11
12Authors:
13 Jean Delvare <khali@linux-fr.org>
14 Yuan Mu (Winbond)
15 Rudolf Marek <r.marek@assembler.cz>
16 David Hubbard <david.c.hubbard@gmail.com>
17
18Description
19-----------
20
21This driver implements support for the Winbond W83627EHF, W83627EHG, and
22W83627DHG super I/O chips. We will refer to them collectively as Winbond chips.
23
24The chips implement three temperature sensors, five fan rotation
25speed sensors, ten analog voltage sensors (only nine for the 627DHG), one
26VID (6 pins), alarms with beep warnings (control unimplemented), and
27some automatic fan regulation strategies (plus manual fan control mode).
28
29Temperatures are measured in degrees Celsius and measurement resolution is 1
30degC for temp1 and 0.5 degC for temp2 and temp3. An alarm is triggered when
31the temperature gets higher than high limit; it stays on until the temperature
32falls below the hysteresis value.
33
34Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
35triggered if the rotation speed has dropped below a programmable limit. Fan
36readings can be divided by a programmable divider (1, 2, 4, 8, 16, 32, 64 or
37128) to give the readings more range or accuracy. The driver sets the most
38suitable fan divisor itself. Some fans might not be present because they
39share pins with other functions.
40
41Voltage sensors (also known as IN sensors) report their values in millivolts.
42An alarm is triggered if the voltage has crossed a programmable minimum
43or maximum limit.
44
45The driver supports automatic fan control mode known as Thermal Cruise.
46In this mode, the chip attempts to keep the measured temperature in a
47predefined temperature range. If the temperature goes out of range, fan
48is driven slower/faster to reach the predefined range again.
49
50The mode works for fan1-fan4. Mapping of temperatures to pwm outputs is as
51follows:
52
53temp1 -> pwm1
54temp2 -> pwm2
55temp3 -> pwm3
56prog -> pwm4 (the programmable setting is not supported by the driver)
57
58/sys files
59----------
60
61name - this is a standard hwmon device entry. For the W83627EHF and W83627EHG,
62 it is set to "w83627ehf" and for the W83627DHG it is set to "w83627dhg"
63
64pwm[1-4] - this file stores PWM duty cycle or DC value (fan speed) in range:
65 0 (stop) to 255 (full)
66
67pwm[1-4]_enable - this file controls mode of fan/temperature control:
68 * 1 Manual Mode, write to pwm file any value 0-255 (full speed)
69 * 2 Thermal Cruise
70
71Thermal Cruise mode
72-------------------
73
74If the temperature is in the range defined by:
75
76pwm[1-4]_target - set target temperature, unit millidegree Celsius
77 (range 0 - 127000)
78pwm[1-4]_tolerance - tolerance, unit millidegree Celsius (range 0 - 15000)
79
80there are no changes to fan speed. Once the temperature leaves the interval,
81fan speed increases (temp is higher) or decreases if lower than desired.
82There are defined steps and times, but not exported by the driver yet.
83
84pwm[1-4]_min_output - minimum fan speed (range 1 - 255), when the temperature
85 is below defined range.
86pwm[1-4]_stop_time - how many milliseconds [ms] must elapse to switch
87 corresponding fan off. (when the temperature was below
88 defined range).
89
90Note: last two functions are influenced by other control bits, not yet exported
91 by the driver, so a change might not have any effect.
92
93Implementation Details
94----------------------
95
96Future driver development should bear in mind that the following registers have
97different functions on the 627EHF and the 627DHG. Some registers also have
98different power-on default values, but BIOS should already be loading
99appropriate defaults. Note that bank selection must be performed as is currently
100done in the driver for all register addresses.
101
1020x49: only on DHG, selects temperature source for AUX fan, CPU fan0
1030x4a: not completely documented for the EHF and the DHG documentation assigns
104 different behavior to bits 7 and 6, including extending the temperature
105 input selection to SmartFan I, not just SmartFan III. Testing on the EHF
106 will reveal whether they are compatible or not.
107
1080x58: Chip ID: 0xa1=EHF 0xc1=DHG
1090x5e: only on DHG, has bits to enable "current mode" temperature detection and
110 critical temperature protection
1110x45b: only on EHF, bit 3, vin4 alarm (EHF supports 10 inputs, only 9 on DHG)
1120x552: only on EHF, vin4
1130x558: only on EHF, vin4 high limit
1140x559: only on EHF, vin4 low limit
1150x6b: only on DHG, SYS fan critical temperature
1160x6c: only on DHG, CPU fan0 critical temperature
1170x6d: only on DHG, AUX fan critical temperature
1180x6e: only on DHG, CPU fan1 critical temperature
119
1200x50-0x55 and 0x650-0x657 are marked "Test Register" for the EHF, but "Reserved
121 Register" for the DHG
122
123The DHG also supports PECI, where the DHG queries Intel CPU temperatures, and
124the ICH8 southbridge gets that data via PECI from the DHG, so that the
125southbridge drives the fans. And the DHG supports SST, a one-wire serial bus.