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7f15b664 M |
1 | Kernel driver via686a |
2 | ===================== | |
3 | ||
4 | Supported chips: | |
b04f2f7d | 5 | |
7f15b664 | 6 | * Via VT82C686A, VT82C686B Southbridge Integrated Hardware Monitor |
b04f2f7d | 7 | |
7f15b664 | 8 | Prefix: 'via686a' |
b04f2f7d | 9 | |
7f15b664 | 10 | Addresses scanned: ISA in PCI-space encoded address |
b04f2f7d | 11 | |
0ea6e611 | 12 | Datasheet: On request through web form (http://www.via.com.tw/en/resources/download-center/) |
7f15b664 M |
13 | |
14 | Authors: | |
b04f2f7d MCC |
15 | - Kyösti Mälkki <kmalkki@cc.hut.fi>, |
16 | - Mark D. Studebaker <mdsxyz123@yahoo.com> | |
17 | - Bob Dougherty <bobd@stanford.edu> | |
18 | - (Some conversion-factor data were contributed by | |
19 | - Jonathan Teh Soon Yew <j.teh@iname.com> | |
20 | - and Alex van Kaam <darkside@chello.nl>.) | |
7f15b664 M |
21 | |
22 | Module Parameters | |
23 | ----------------- | |
24 | ||
b04f2f7d | 25 | ======================= ======================================================= |
b918ecd2 | 26 | force_addr=0xaddr Set the I/O base address. Useful for boards that |
b04f2f7d MCC |
27 | don't set the address in the BIOS. Look for a BIOS |
28 | upgrade before resorting to this. Does not do a | |
29 | PCI force; the via686a must still be present in lspci. | |
30 | Don't use this unless the driver complains that the | |
31 | base address is not set. | |
32 | Example: 'modprobe via686a force_addr=0x6000' | |
33 | ======================= ======================================================= | |
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34 | |
35 | Description | |
36 | ----------- | |
37 | ||
38 | The driver does not distinguish between the chips and reports | |
39 | all as a 686A. | |
40 | ||
41 | The Via 686a southbridge has integrated hardware monitor functionality. | |
42 | It also has an I2C bus, but this driver only supports the hardware monitor. | |
ccf988b6 | 43 | For the I2C bus driver, see <file:Documentation/i2c/busses/i2c-viapro.rst> |
7f15b664 M |
44 | |
45 | The Via 686a implements three temperature sensors, two fan rotation speed | |
46 | sensors, five voltage sensors and alarms. | |
47 | ||
48 | Temperatures are measured in degrees Celsius. An alarm is triggered once | |
49 | when the Overtemperature Shutdown limit is crossed; it is triggered again | |
50 | as soon as it drops below the hysteresis value. | |
51 | ||
52 | Fan rotation speeds are reported in RPM (rotations per minute). An alarm is | |
53 | triggered if the rotation speed has dropped below a programmable limit. Fan | |
54 | readings can be divided by a programmable divider (1, 2, 4 or 8) to give | |
55 | the readings more range or accuracy. Not all RPM values can accurately be | |
56 | represented, so some rounding is done. With a divider of 2, the lowest | |
57 | representable value is around 2600 RPM. | |
58 | ||
59 | Voltage sensors (also known as IN sensors) report their values in volts. | |
60 | An alarm is triggered if the voltage has crossed a programmable minimum | |
12087a36 | 61 | or maximum limit. Voltages are internally scaled, so each voltage channel |
7f15b664 M |
62 | has a different resolution and range. |
63 | ||
64 | If an alarm triggers, it will remain triggered until the hardware register | |
65 | is read at least once. This means that the cause for the alarm may | |
66 | already have disappeared! Note that in the current implementation, all | |
67 | hardware registers are read whenever any data is read (unless it is less | |
68 | than 1.5 seconds since the last update). This means that you can easily | |
69 | miss once-only alarms. | |
70 | ||
71 | The driver only updates its values each 1.5 seconds; reading it more often | |
72 | will do no harm, but will return 'old' values. | |
b918ecd2 JD |
73 | |
74 | Known Issues | |
75 | ------------ | |
76 | ||
77 | This driver handles sensors integrated in some VIA south bridges. It is | |
78 | possible that a motherboard maker used a VT82C686A/B chip as part of a | |
79 | product design but was not interested in its hardware monitoring features, | |
80 | in which case the sensor inputs will not be wired. This is the case of | |
81 | the Asus K7V, A7V and A7V133 motherboards, to name only a few of them. | |
82 | So, if you need the force_addr parameter, and end up with values which | |
83 | don't seem to make any sense, don't look any further: your chip is simply | |
84 | not wired for hardware monitoring. |