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authorRudolf Marek <r.marek@sh.cvut.cz>2006-07-05 12:15:31 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2006-09-28 18:31:12 -0400
commit563daaf4047464eef5ffcb46194a99c1a8f2260e (patch)
tree19a4f8c8f83986b1c84a6228c9178931e2066719 /Documentation/hwmon
parent08c79950a047dbaccf05d70a203db2ee75ac3bd8 (diff)
hwmon: Documentation update for w83627ehf
Add documentation for the w83627ehf hardware monitoring driver. Signed-off-by: Rudolf Marek <r.marek@sh.cvut.cz> Signed-off-by: Jean Delvare <khali@linux-fr.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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1Kernel driver w83627ehf
2=======================
3
4Supported chips:
5 * Winbond W83627EHF/EHG (ISA access ONLY)
6 Prefix: 'w83627ehf'
7 Addresses scanned: ISA address retrieved from Super I/O registers
8 Datasheet: http://www.winbond-usa.com/products/winbond_products/pdfs/PCIC/W83627EHF_%20W83627EHGb.pdf
9
10Authors:
11 Jean Delvare <khali@linux-fr.org>
12 Yuan Mu <Ymu@Winbond.com.tw>
13 Rudolf Marek <r.marek@sh.cvut.cz>
14
15Description
16-----------
17
18This driver implements support for the Winbond W83627EHF and W83627EHG
19super I/O chips. We will refer to them collectively as Winbond chips.
20
21The chips implement three temperature sensors, five fan rotation
22speed sensors, ten analog voltage sensors, alarms with beep warnings (control
23unimplemented), and some automatic fan regulation strategies (plus manual
24fan control mode).
25
26Temperatures are measured in degrees Celsius and measurement resolution is 1
27degC for temp1 and 0.5 degC for temp2 and temp3. An alarm is triggered when
28the temperature gets higher than high limit; it stays on until the temperature
29falls below the Hysteresis value.
30
31Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
32triggered if the rotation speed has dropped below a programmable limit. Fan
33readings can be divided by a programmable divider (1, 2, 4, 8, 16, 32, 64 or
34128) to give the readings more range or accuracy. The driver sets the most
35suitable fan divisor itself. Some fans might not be present because they
36share pins with other functions.
37
38Voltage sensors (also known as IN sensors) report their values in millivolts.
39An alarm is triggered if the voltage has crossed a programmable minimum
40or maximum limit.
41
42The driver supports automatic fan control mode known as Thermal Cruise.
43In this mode, the chip attempts to keep the measured temperature in a
44predefined temperature range. If the temperature goes out of range, fan
45is driven slower/faster to reach the predefined range again.
46
47The mode works for fan1-fan4. Mapping of temperatures to pwm outputs is as
48follows:
49
50temp1 -> pwm1
51temp2 -> pwm2
52temp3 -> pwm3
53prog -> pwm4 (the programmable setting is not supported by the driver)
54
55/sys files
56----------
57
58pwm[1-4] - this file stores PWM duty cycle or DC value (fan speed) in range:
59 0 (stop) to 255 (full)
60
61pwm[1-4]_enable - this file controls mode of fan/temperature control:
62 * 1 Manual Mode, write to pwm file any value 0-255 (full speed)
63 * 2 Thermal Cruise
64
65Thermal Cruise mode
66-------------------
67
68If the temperature is in the range defined by:
69
70pwm[1-4]_target - set target temperature, unit millidegree Celcius
71 (range 0 - 127000)
72pwm[1-4]_tolerance - tolerance, unit millidegree Celcius (range 0 - 15000)
73
74there are no changes to fan speed. Once the temperature leaves the interval,
75fan speed increases (temp is higher) or decreases if lower than desired.
76There are defined steps and times, but not exported by the driver yet.
77
78pwm[1-4]_min_output - minimum fan speed (range 1 - 255), when the temperature
79 is below defined range.
80pwm[1-4]_stop_time - how many milliseconds [ms] must elapse to switch
81 corresponding fan off. (when the temperature was below
82 defined range).
83
84Note: last two functions are influenced by other control bits, not yet exported
85 by the driver, so a change might not have any effect.