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/W83791D_W83791Gb.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:

      Shane Huang (Winbond),

      Rudolf Marek <r.marek@assembler.cz>

  Additional contributors:
      Sven Anders <anders@anduras.de>

      Marc Hulsman <m.hulsman@tudelft.nl>

  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. The W83791G
  chip appears to be the same as the W83791D but is lead free.

  
  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, ten voltage sensors,
  five fan rotation speed sensors and manual PWM control of each fan.

  
  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.

  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.

  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, 16,
  32, 64 or 128 for all fans) to give the readings more range or accuracy.

  Each fan controlled is controlled by PWM. The PWM duty cycle can be read and
  set for each fan separately. Valid values range from 0 (stop) to 255 (full).

  PWM 1-3 support Thermal Cruise mode, in which the PWMs are automatically
  regulated to keep respectively temp 1-3 at a certain target temperature.
  See below for the description of the sysfs-interface.

  The w83791d has a global bit used to enable beeping from the speaker when an
  alarm is triggered as well as a bitmask to enable or disable the beep for
  specific alarms. You need both the global beep enable bit and the
  corresponding beep bit to be on for a triggered alarm to sound a beep.

  The sysfs interface to the global enable is via the sysfs beep_enable file.

  This file is used for both legacy and new code.
  
  The sysfs interface to the beep bitmask has migrated from the original legacy
  method of a single sysfs beep_mask file to a newer method using multiple
  *_beep files as described in .../Documentation/hwmon/sysfs-interface.

  A similar change has occurred for the bitmap corresponding to the alarms. The

  original legacy method used a single sysfs alarms file containing a bitmap
  of triggered alarms. The newer method uses multiple sysfs *_alarm files
  (again following the pattern described in sysfs-interface).
  
  Since both methods read and write the underlying hardware, they can be used
  interchangeably and changes in one will automatically be reflected by
  the other. If you use the legacy bitmask method, your user-space code is
  responsible for handling the fact that the alarms and beep_mask bitmaps
  are not the same (see the table below).
  
  NOTE: All new code should be written to use the newer sysfs-interface
  specification as that avoids bitmap problems and is the preferred interface
  going forward.
  
  The driver reads the hardware chip values at most once every three seconds.
  User mode code requesting values more often will receive cached values.

  /sys files
  ----------
  The sysfs-interface is documented in the 'sysfs-interface' file. Only
  chip-specific options are documented here.
  
  pwm[1-3]_enable -	this file controls mode of fan/temperature control for
  			fan 1-3. Fan/PWM 4-5 only support manual mode.
  		            * 1 Manual mode

  		            * 2 Thermal Cruise mode

  		            * 3 Fan Speed Cruise mode (no further support)

  temp[1-3]_target -	defines the target temperature for Thermal Cruise mode.
  			Unit: millidegree Celsius
  			RW
  
  temp[1-3]_tolerance -	temperature tolerance for Thermal Cruise mode.
  			Specifies an interval around the target temperature
  			in which the fan speed is not changed.
  			Unit: millidegree Celsius
  			RW

  Alarms bitmap vs. beep_mask bitmask
  ------------------------------------
  For legacy code using the alarms and beep_mask files:
  
  in0 (VCORE)  :  alarms: 0x000001 beep_mask: 0x000001
  in1 (VINR0)  :  alarms: 0x000002 beep_mask: 0x002000 <== mismatch
  in2 (+3.3VIN):  alarms: 0x000004 beep_mask: 0x000004
  in3 (5VDD)   :  alarms: 0x000008 beep_mask: 0x000008
  in4 (+12VIN) :  alarms: 0x000100 beep_mask: 0x000100
  in5 (-12VIN) :  alarms: 0x000200 beep_mask: 0x000200
  in6 (-5VIN)  :  alarms: 0x000400 beep_mask: 0x000400
  in7 (VSB)    :  alarms: 0x080000 beep_mask: 0x010000 <== mismatch
  in8 (VBAT)   :  alarms: 0x100000 beep_mask: 0x020000 <== mismatch
  in9 (VINR1)  :  alarms: 0x004000 beep_mask: 0x004000
  temp1        :  alarms: 0x000010 beep_mask: 0x000010
  temp2        :  alarms: 0x000020 beep_mask: 0x000020
  temp3        :  alarms: 0x002000 beep_mask: 0x000002 <== mismatch
  fan1         :  alarms: 0x000040 beep_mask: 0x000040
  fan2         :  alarms: 0x000080 beep_mask: 0x000080
  fan3         :  alarms: 0x000800 beep_mask: 0x000800
  fan4         :  alarms: 0x200000 beep_mask: 0x200000
  fan5         :  alarms: 0x400000 beep_mask: 0x400000
  tart1        :  alarms: 0x010000 beep_mask: 0x040000 <== mismatch
  tart2        :  alarms: 0x020000 beep_mask: 0x080000 <== mismatch
  tart3        :  alarms: 0x040000 beep_mask: 0x100000 <== mismatch
  case_open    :  alarms: 0x001000 beep_mask: 0x001000
  global_enable:  alarms: -------- beep_mask: 0x800000 (modified via beep_enable)