Kernel driver w83791d
=====================

Supported chips:
  * Winbond W83791D
    Prefix: 'w83791d'
    Addresses scanned: I2C 0x2c - 0x2f
    Datasheet: http://www.winbond-usa.com/products/winbond_products/pdfs/PCIC/W83791Da.pdf

Author: Charles Spirakis <bezaur@gmail.com>

This driver was derived from the w83781d.c and w83792d.c source files.

Credits:
  w83781d.c:
    Frodo Looijaard <frodol@dds.nl>,
    Philip Edelbrock <phil@netroedge.com>,
    and Mark Studebaker <mdsxyz123@yahoo.com>
  w83792d.c:
    Chunhao Huang <DZShen@Winbond.com.tw>,
    Rudolf Marek <r.marek@sh.cvut.cz>

Module Parameters
-----------------

* init boolean
  (default 0)
  Use 'init=1' to have the driver do extra software initializations.
  The default behavior is to do the minimum initialization possible
  and depend on the BIOS to properly setup the chip. If you know you
  have a w83791d and you're having problems, try init=1 before trying
  reset=1.

* reset boolean
  (default 0)
  Use 'reset=1' to reset the chip (via index 0x40, bit 7). The default
  behavior is no chip reset to preserve BIOS settings.

* force_subclients=bus,caddr,saddr,saddr
  This is used to force the i2c addresses for subclients of
  a certain chip. Example usage is `force_subclients=0,0x2f,0x4a,0x4b'
  to force the subclients of chip 0x2f on bus 0 to i2c addresses
  0x4a and 0x4b.


Description
-----------

This driver implements support for the Winbond W83791D chip.

Detection of the chip can sometimes be foiled because it can be in an
internal state that allows no clean access (Bank with ID register is not
currently selected). If you know the address of the chip, use a 'force'
parameter; this will put it into a more well-behaved state first.

The driver implements three temperature sensors, five fan rotation speed
sensors, and ten voltage sensors.

Temperatures are measured in degrees Celsius and measurement resolution is 1
degC for temp1 and 0.5 degC for temp2 and temp3. An alarm is triggered when
the temperature gets higher than the Overtemperature Shutdown value; it stays
on until the temperature falls 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, 8 for fan 1/2/3
and 1, 2, 4, 8, 16, 32, 64 or 128 for fan 4/5) to give the readings more
range or accuracy.

Voltage sensors (also known as IN sensors) report their values in millivolts.
An alarm is triggered if the voltage has crossed a programmable minimum
or maximum limit.

Alarms are provided as output from a "realtime status register". The
following bits are defined:

bit - alarm on:
0  - Vcore
1  - VINR0
2  - +3.3VIN
3  - 5VDD
4  - temp1
5  - temp2
6  - fan1
7  - fan2
8  - +12VIN
9  - -12VIN
10 - -5VIN
11 - fan3
12 - chassis
13 - temp3
14 - VINR1
15 - reserved
16 - tart1
17 - tart2
18 - tart3
19 - VSB
20 - VBAT
21 - fan4
22 - fan5
23 - reserved

When an alarm goes off, you can be warned by a beeping signal through your
computer speaker. It is possible to enable all beeping globally, or only
the beeping for some alarms.

The driver only reads the chip values each 3 seconds; reading them more
often will do no harm, but will return 'old' values.

W83791D TODO:
---------------
Provide a patch for per-file alarms as discussed on the mailing list
Provide a patch for smart-fan control (still need appropriate motherboard/fans)