Ke Dong | eb337a3 | 2012-09-26 19:17:39 -0700 | [diff] [blame] | 1 | Kernel driver via686a |
| 2 | ===================== |
| 3 | |
| 4 | Supported chips: |
| 5 | * Via VT82C686A, VT82C686B Southbridge Integrated Hardware Monitor |
| 6 | Prefix: 'via686a' |
| 7 | Addresses scanned: ISA in PCI-space encoded address |
| 8 | Datasheet: On request through web form (http://www.via.com.tw/en/support/datasheets/) |
| 9 | |
| 10 | Authors: |
| 11 | Kyösti Mälkki <kmalkki@cc.hut.fi>, |
| 12 | Mark D. Studebaker <mdsxyz123@yahoo.com> |
| 13 | Bob Dougherty <bobd@stanford.edu> |
| 14 | (Some conversion-factor data were contributed by |
| 15 | Jonathan Teh Soon Yew <j.teh@iname.com> |
| 16 | and Alex van Kaam <darkside@chello.nl>.) |
| 17 | |
| 18 | Module Parameters |
| 19 | ----------------- |
| 20 | |
| 21 | force_addr=0xaddr Set the I/O base address. Useful for boards that |
| 22 | don't set the address in the BIOS. Look for a BIOS |
| 23 | upgrade before resorting to this. Does not do a |
| 24 | PCI force; the via686a must still be present in lspci. |
| 25 | Don't use this unless the driver complains that the |
| 26 | base address is not set. |
| 27 | Example: 'modprobe via686a force_addr=0x6000' |
| 28 | |
| 29 | Description |
| 30 | ----------- |
| 31 | |
| 32 | The driver does not distinguish between the chips and reports |
| 33 | all as a 686A. |
| 34 | |
| 35 | The Via 686a southbridge has integrated hardware monitor functionality. |
| 36 | It also has an I2C bus, but this driver only supports the hardware monitor. |
| 37 | For the I2C bus driver, see <file:Documentation/i2c/busses/i2c-viapro> |
| 38 | |
| 39 | The Via 686a implements three temperature sensors, two fan rotation speed |
| 40 | sensors, five voltage sensors and alarms. |
| 41 | |
| 42 | Temperatures are measured in degrees Celsius. An alarm is triggered once |
| 43 | when the Overtemperature Shutdown limit is crossed; it is triggered again |
| 44 | as soon as it drops below the hysteresis value. |
| 45 | |
| 46 | Fan rotation speeds are reported in RPM (rotations per minute). An alarm is |
| 47 | triggered if the rotation speed has dropped below a programmable limit. Fan |
| 48 | readings can be divided by a programmable divider (1, 2, 4 or 8) to give |
| 49 | the readings more range or accuracy. Not all RPM values can accurately be |
| 50 | represented, so some rounding is done. With a divider of 2, the lowest |
| 51 | representable value is around 2600 RPM. |
| 52 | |
| 53 | Voltage sensors (also known as IN sensors) report their values in volts. |
| 54 | An alarm is triggered if the voltage has crossed a programmable minimum |
| 55 | or maximum limit. Voltages are internally scalled, so each voltage channel |
| 56 | has a different resolution and range. |
| 57 | |
| 58 | If an alarm triggers, it will remain triggered until the hardware register |
| 59 | is read at least once. This means that the cause for the alarm may |
| 60 | already have disappeared! Note that in the current implementation, all |
| 61 | hardware registers are read whenever any data is read (unless it is less |
| 62 | than 1.5 seconds since the last update). This means that you can easily |
| 63 | miss once-only alarms. |
| 64 | |
| 65 | The driver only updates its values each 1.5 seconds; reading it more often |
| 66 | will do no harm, but will return 'old' values. |
| 67 | |
| 68 | Known Issues |
| 69 | ------------ |
| 70 | |
| 71 | This driver handles sensors integrated in some VIA south bridges. It is |
| 72 | possible that a motherboard maker used a VT82C686A/B chip as part of a |
| 73 | product design but was not interested in its hardware monitoring features, |
| 74 | in which case the sensor inputs will not be wired. This is the case of |
| 75 | the Asus K7V, A7V and A7V133 motherboards, to name only a few of them. |
| 76 | So, if you need the force_addr parameter, and end up with values which |
| 77 | don't seem to make any sense, don't look any further: your chip is simply |
| 78 | not wired for hardware monitoring. |