Kernel driver w83791d¶
Addresses scanned: I2C 0x2c - 0x2f
Author: Charles Spirakis <email@example.com>
This driver was derived from the w83781d.c and w83792d.c source files.
- init boolean
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
Use ‘reset=1’ to reset the chip (via index 0x40, bit 7). The default behavior is no chip reset to preserve BIOS settings.
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.
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.rst.
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.
The sysfs-interface is documented in the ‘sysfs-interface’ file. Only chip-specific options are documented here.
this file controls mode of fan/temperature control for fan 1-3. Fan/PWM 4-5 only support manual mode.
|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:
|in1 (VINR0)||0x000002||0x002000||<== mismatch|
|in7 (VSB)||0x080000||0x010000||<== mismatch|
|in8 (VBAT)||0x100000||0x020000||<== mismatch|
|global_enable||0x800000||(modified via beep_enable)|