From 7f15b66468b7003d5241e352a007e73be5519b20 Mon Sep 17 00:00:00 2001 From: "R.Marek@sh.cvut.cz" Date: Thu, 26 May 2005 12:42:19 +0000 Subject: [PATCH] I2C: documentation update 2/3 This patch adds missing documentation for system health monitoring chips. I would like to thank all people, who helped me with this project. Signed-off-by: Rudolf Marek Signed-off-by: Greg Kroah-Hartman --- Documentation/i2c/chips/via686a | 65 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100644 Documentation/i2c/chips/via686a (limited to 'Documentation/i2c/chips/via686a') diff --git a/Documentation/i2c/chips/via686a b/Documentation/i2c/chips/via686a new file mode 100644 index 00000000000..b82014cb7c5 --- /dev/null +++ b/Documentation/i2c/chips/via686a @@ -0,0 +1,65 @@ +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/support/datasheets/) + +Authors: + Kyösti Mälkki , + Mark D. Studebaker + Bob Dougherty + (Some conversion-factor data were contributed by + Jonathan Teh Soon Yew + and Alex van Kaam .) + +Module Parameters +----------------- + +force_addr=0xaddr Set the I/O base address. Useful for Asus A7V boards + that don't set the address in the BIOS. 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 + +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. -- cgit v1.2.3-70-g09d2