| Kernel driver via686a |
| ===================== |
| |
| Supported chips: |
| * Via VT82C686A, VT82C686B Southbridge Integrated Hardware Monitor |
| Prefix: 'via686a' |
| Addresses scanned: ISA in PCI-space encoded address |
| Datasheet: On request through web form (http://www.via.com.tw/en/resources/download-center/) |
| |
| Authors: |
| Kyösti Mälkki <kmalkki@cc.hut.fi>, |
| Mark D. Studebaker <mdsxyz123@yahoo.com> |
| Bob Dougherty <bobd@stanford.edu> |
| (Some conversion-factor data were contributed by |
| Jonathan Teh Soon Yew <j.teh@iname.com> |
| and Alex van Kaam <darkside@chello.nl>.) |
| |
| Module Parameters |
| ----------------- |
| |
| force_addr=0xaddr Set the I/O base address. Useful for boards that |
| don't set the address in the BIOS. Look for a BIOS |
| upgrade before resorting to this. Does not do a |
| PCI force; the via686a must still be present in lspci. |
| Don't use this unless the driver complains that the |
| base address is not set. |
| Example: 'modprobe via686a force_addr=0x6000' |
| |
| Description |
| ----------- |
| |
| The driver does not distinguish between the chips and reports |
| all as a 686A. |
| |
| The Via 686a southbridge has integrated hardware monitor functionality. |
| It also has an I2C bus, but this driver only supports the hardware monitor. |
| For the I2C bus driver, see <file:Documentation/i2c/busses/i2c-viapro> |
| |
| The Via 686a implements three temperature sensors, two fan rotation speed |
| sensors, five voltage sensors and alarms. |
| |
| Temperatures are measured in degrees Celsius. An alarm is triggered once |
| when the Overtemperature Shutdown limit is crossed; it is triggered again |
| as soon as it drops below the hysteresis value. |
| |
| Fan rotation speeds are reported in RPM (rotations per minute). An alarm is |
| triggered if the rotation speed has dropped below a programmable limit. Fan |
| readings can be divided by a programmable divider (1, 2, 4 or 8) to give |
| the readings more range or accuracy. Not all RPM values can accurately be |
| represented, so some rounding is done. With a divider of 2, the lowest |
| representable value is around 2600 RPM. |
| |
| Voltage sensors (also known as IN sensors) report their values in volts. |
| An alarm is triggered if the voltage has crossed a programmable minimum |
| or maximum limit. Voltages are internally scalled, so each voltage channel |
| has a different resolution and range. |
| |
| If an alarm triggers, it will remain triggered until the hardware register |
| is read at least once. This means that the cause for the alarm may |
| already have disappeared! Note that in the current implementation, all |
| hardware registers are read whenever any data is read (unless it is less |
| than 1.5 seconds since the last update). This means that you can easily |
| miss once-only alarms. |
| |
| The driver only updates its values each 1.5 seconds; reading it more often |
| will do no harm, but will return 'old' values. |
| |
| Known Issues |
| ------------ |
| |
| This driver handles sensors integrated in some VIA south bridges. It is |
| possible that a motherboard maker used a VT82C686A/B chip as part of a |
| product design but was not interested in its hardware monitoring features, |
| in which case the sensor inputs will not be wired. This is the case of |
| the Asus K7V, A7V and A7V133 motherboards, to name only a few of them. |
| So, if you need the force_addr parameter, and end up with values which |
| don't seem to make any sense, don't look any further: your chip is simply |
| not wired for hardware monitoring. |