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- Kernel driver w83627ehf
- =======================
- Supported chips:
- * Winbond W83627EHF/EHG (ISA access ONLY)
- Prefix: 'w83627ehf'
- Addresses scanned: ISA address retrieved from Super I/O registers
- Datasheet: http://www.winbond-usa.com/products/winbond_products/pdfs/PCIC/W83627EHF_%20W83627EHGb.pdf
- Authors:
- Jean Delvare <khali@linux-fr.org>
- Yuan Mu (Winbond)
- Rudolf Marek <r.marek@assembler.cz>
- Description
- -----------
- This driver implements support for the Winbond W83627EHF and W83627EHG
- super I/O chips. We will refer to them collectively as Winbond chips.
- The chips implement three temperature sensors, five fan rotation
- speed sensors, ten analog voltage sensors, alarms with beep warnings (control
- unimplemented), and some automatic fan regulation strategies (plus manual
- fan control mode).
- 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 high limit; 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, 16, 32, 64 or
- 128) to give the readings more range or accuracy. The driver sets the most
- suitable fan divisor itself. Some fans might not be present because they
- share pins with other functions.
- 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.
- The driver supports automatic fan control mode known as Thermal Cruise.
- In this mode, the chip attempts to keep the measured temperature in a
- predefined temperature range. If the temperature goes out of range, fan
- is driven slower/faster to reach the predefined range again.
- The mode works for fan1-fan4. Mapping of temperatures to pwm outputs is as
- follows:
- temp1 -> pwm1
- temp2 -> pwm2
- temp3 -> pwm3
- prog -> pwm4 (the programmable setting is not supported by the driver)
- /sys files
- ----------
- pwm[1-4] - this file stores PWM duty cycle or DC value (fan speed) in range:
- 0 (stop) to 255 (full)
- pwm[1-4]_enable - this file controls mode of fan/temperature control:
- * 1 Manual Mode, write to pwm file any value 0-255 (full speed)
- * 2 Thermal Cruise
- Thermal Cruise mode
- -------------------
- If the temperature is in the range defined by:
- pwm[1-4]_target - set target temperature, unit millidegree Celsius
- (range 0 - 127000)
- pwm[1-4]_tolerance - tolerance, unit millidegree Celsius (range 0 - 15000)
- there are no changes to fan speed. Once the temperature leaves the interval,
- fan speed increases (temp is higher) or decreases if lower than desired.
- There are defined steps and times, but not exported by the driver yet.
- pwm[1-4]_min_output - minimum fan speed (range 1 - 255), when the temperature
- is below defined range.
- pwm[1-4]_stop_time - how many milliseconds [ms] must elapse to switch
- corresponding fan off. (when the temperature was below
- defined range).
- Note: last two functions are influenced by other control bits, not yet exported
- by the driver, so a change might not have any effect.
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