1 Kernel driver via686a 1 Kernel driver via686a
2 ===================== 2 =====================
3 3
4 Supported chips: 4 Supported chips:
5 5
6 * Via VT82C686A, VT82C686B Southbridge Inte 6 * Via VT82C686A, VT82C686B Southbridge Integrated Hardware Monitor
7 7
8 Prefix: 'via686a' 8 Prefix: 'via686a'
9 9
10 Addresses scanned: ISA in PCI-space encode 10 Addresses scanned: ISA in PCI-space encoded address
11 11
12 Datasheet: On request through web form (ht 12 Datasheet: On request through web form (http://www.via.com.tw/en/resources/download-center/)
13 13
14 Authors: 14 Authors:
15 - Kyösti Mälkki <kmalkki@cc.hut.fi>, 15 - Kyösti Mälkki <kmalkki@cc.hut.fi>,
16 - Mark D. Studebaker <mdsxyz123@yahoo.c 16 - Mark D. Studebaker <mdsxyz123@yahoo.com>
17 - Bob Dougherty <bobd@stanford.edu> 17 - Bob Dougherty <bobd@stanford.edu>
18 - (Some conversion-factor data were co 18 - (Some conversion-factor data were contributed by
19 - Jonathan Teh Soon Yew <j.teh@iname.co 19 - Jonathan Teh Soon Yew <j.teh@iname.com>
20 - and Alex van Kaam <darkside@chello.nl 20 - and Alex van Kaam <darkside@chello.nl>.)
21 21
22 Module Parameters 22 Module Parameters
23 ----------------- 23 -----------------
24 24
25 ======================= ====================== 25 ======================= =======================================================
26 force_addr=0xaddr Set the I/O base addre 26 force_addr=0xaddr Set the I/O base address. Useful for boards that
27 don't set the address 27 don't set the address in the BIOS. Look for a BIOS
28 upgrade before resorti 28 upgrade before resorting to this. Does not do a
29 PCI force; the via686a 29 PCI force; the via686a must still be present in lspci.
30 Don't use this unless 30 Don't use this unless the driver complains that the
31 base address is not se 31 base address is not set.
32 Example: 'modprobe via 32 Example: 'modprobe via686a force_addr=0x6000'
33 ======================= ====================== 33 ======================= =======================================================
34 34
35 Description 35 Description
36 ----------- 36 -----------
37 37
38 The driver does not distinguish between the ch 38 The driver does not distinguish between the chips and reports
39 all as a 686A. 39 all as a 686A.
40 40
41 The Via 686a southbridge has integrated hardwa 41 The Via 686a southbridge has integrated hardware monitor functionality.
42 It also has an I2C bus, but this driver only s 42 It also has an I2C bus, but this driver only supports the hardware monitor.
43 For the I2C bus driver, see <file:Documentatio 43 For the I2C bus driver, see <file:Documentation/i2c/busses/i2c-viapro.rst>
44 44
45 The Via 686a implements three temperature sens 45 The Via 686a implements three temperature sensors, two fan rotation speed
46 sensors, five voltage sensors and alarms. 46 sensors, five voltage sensors and alarms.
47 47
48 Temperatures are measured in degrees Celsius. 48 Temperatures are measured in degrees Celsius. An alarm is triggered once
49 when the Overtemperature Shutdown limit is cro 49 when the Overtemperature Shutdown limit is crossed; it is triggered again
50 as soon as it drops below the hysteresis value 50 as soon as it drops below the hysteresis value.
51 51
52 Fan rotation speeds are reported in RPM (rotat 52 Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
53 triggered if the rotation speed has dropped be 53 triggered if the rotation speed has dropped below a programmable limit. Fan
54 readings can be divided by a programmable divi 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 R 55 the readings more range or accuracy. Not all RPM values can accurately be
56 represented, so some rounding is done. With a 56 represented, so some rounding is done. With a divider of 2, the lowest
57 representable value is around 2600 RPM. 57 representable value is around 2600 RPM.
58 58
59 Voltage sensors (also known as IN sensors) rep 59 Voltage sensors (also known as IN sensors) report their values in volts.
60 An alarm is triggered if the voltage has cross 60 An alarm is triggered if the voltage has crossed a programmable minimum
61 or maximum limit. Voltages are internally scal 61 or maximum limit. Voltages are internally scaled, so each voltage channel
62 has a different resolution and range. 62 has a different resolution and range.
63 63
64 If an alarm triggers, it will remain triggered 64 If an alarm triggers, it will remain triggered until the hardware register
65 is read at least once. This means that the cau 65 is read at least once. This means that the cause for the alarm may
66 already have disappeared! Note that in the cur 66 already have disappeared! Note that in the current implementation, all
67 hardware registers are read whenever any data 67 hardware registers are read whenever any data is read (unless it is less
68 than 1.5 seconds since the last update). This 68 than 1.5 seconds since the last update). This means that you can easily
69 miss once-only alarms. 69 miss once-only alarms.
70 70
71 The driver only updates its values each 1.5 se 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. 72 will do no harm, but will return 'old' values.
73 73
74 Known Issues 74 Known Issues
75 ------------ 75 ------------
76 76
77 This driver handles sensors integrated in some 77 This driver handles sensors integrated in some VIA south bridges. It is
78 possible that a motherboard maker used a VT82C 78 possible that a motherboard maker used a VT82C686A/B chip as part of a
79 product design but was not interested in its h 79 product design but was not interested in its hardware monitoring features,
80 in which case the sensor inputs will not be wi 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 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 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 f 83 don't seem to make any sense, don't look any further: your chip is simply
84 not wired for hardware monitoring. 84 not wired for hardware monitoring.
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