[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 <r.marek@sh.cvut.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 65 insertions, 0 deletions

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 <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 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 <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.