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diff --git a/Documentation/hwmon/via686a.rst b/Documentation/hwmon/via686a.rst new file mode 100644 index 000000000..7ab9ddebc --- /dev/null +++ b/Documentation/hwmon/via686a.rst @@ -0,0 +1,84 @@ +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.rst> + +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. |