563daaf404
Add documentation for the w83627ehf hardware monitoring driver. Signed-off-by: Rudolf Marek <r.marek@sh.cvut.cz> Signed-off-by: Jean Delvare <khali@linux-fr.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
85 lines
3.3 KiB
Text
85 lines
3.3 KiB
Text
Kernel driver w83627ehf
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=======================
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Supported chips:
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* Winbond W83627EHF/EHG (ISA access ONLY)
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Prefix: 'w83627ehf'
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Addresses scanned: ISA address retrieved from Super I/O registers
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Datasheet: http://www.winbond-usa.com/products/winbond_products/pdfs/PCIC/W83627EHF_%20W83627EHGb.pdf
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Authors:
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Jean Delvare <khali@linux-fr.org>
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Yuan Mu <Ymu@Winbond.com.tw>
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Rudolf Marek <r.marek@sh.cvut.cz>
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Description
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-----------
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This driver implements support for the Winbond W83627EHF and W83627EHG
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super I/O chips. We will refer to them collectively as Winbond chips.
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The chips implement three temperature sensors, five fan rotation
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speed sensors, ten analog voltage sensors, alarms with beep warnings (control
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unimplemented), and some automatic fan regulation strategies (plus manual
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fan control mode).
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Temperatures are measured in degrees Celsius and measurement resolution is 1
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degC for temp1 and 0.5 degC for temp2 and temp3. An alarm is triggered when
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the temperature gets higher than high limit; it stays on until the temperature
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falls below the Hysteresis value.
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Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
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triggered if the rotation speed has dropped below a programmable limit. Fan
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readings can be divided by a programmable divider (1, 2, 4, 8, 16, 32, 64 or
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128) to give the readings more range or accuracy. The driver sets the most
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suitable fan divisor itself. Some fans might not be present because they
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share pins with other functions.
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Voltage sensors (also known as IN sensors) report their values in millivolts.
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An alarm is triggered if the voltage has crossed a programmable minimum
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or maximum limit.
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The driver supports automatic fan control mode known as Thermal Cruise.
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In this mode, the chip attempts to keep the measured temperature in a
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predefined temperature range. If the temperature goes out of range, fan
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is driven slower/faster to reach the predefined range again.
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The mode works for fan1-fan4. Mapping of temperatures to pwm outputs is as
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follows:
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temp1 -> pwm1
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temp2 -> pwm2
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temp3 -> pwm3
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prog -> pwm4 (the programmable setting is not supported by the driver)
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/sys files
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----------
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pwm[1-4] - this file stores PWM duty cycle or DC value (fan speed) in range:
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0 (stop) to 255 (full)
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pwm[1-4]_enable - this file controls mode of fan/temperature control:
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* 1 Manual Mode, write to pwm file any value 0-255 (full speed)
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* 2 Thermal Cruise
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Thermal Cruise mode
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-------------------
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If the temperature is in the range defined by:
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pwm[1-4]_target - set target temperature, unit millidegree Celcius
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(range 0 - 127000)
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pwm[1-4]_tolerance - tolerance, unit millidegree Celcius (range 0 - 15000)
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there are no changes to fan speed. Once the temperature leaves the interval,
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fan speed increases (temp is higher) or decreases if lower than desired.
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There are defined steps and times, but not exported by the driver yet.
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pwm[1-4]_min_output - minimum fan speed (range 1 - 255), when the temperature
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is below defined range.
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pwm[1-4]_stop_time - how many milliseconds [ms] must elapse to switch
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corresponding fan off. (when the temperature was below
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defined range).
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Note: last two functions are influenced by other control bits, not yet exported
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by the driver, so a change might not have any effect.
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