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Kernel driver w83627ehf

=======================

Supported chips:

  * Winbond W83627EHF/EHG/DHG (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

        DHG datasheet confidential.

Authors:

        Jean Delvare 

        Yuan Mu (Winbond)

        Rudolf Marek 

        David Hubbard 

Description

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This driver implements support for the Winbond W83627EHF, W83627EHG, and

W83627DHG 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 (only nine for the 627DHG), one

VID (6 pins), 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

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name - this is a standard hwmon device entry. For the W83627EHF and W83627EHG,

       it is set to "w83627ehf" and for the W83627DHG it is set to "w83627dhg"

pwm[1-4] - this file stores PWM duty cycle or DC value (fan speed) in range:

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.

Implementation Details

----------------------

Future driver development should bear in mind that the following registers have

different functions on the 627EHF and the 627DHG. Some registers also have

different power-on default values, but BIOS should already be loading

appropriate defaults. Note that bank selection must be performed as is currently

done in the driver for all register addresses.

0x49:  only on DHG, selects temperature source for AUX fan, CPU fan0

0x4a:  not completely documented for the EHF and the DHG documentation assigns

       different behavior to bits 7 and 6, including extending the temperature

       input selection to SmartFan I, not just SmartFan III. Testing on the EHF

       will reveal whether they are compatible or not.

0x58:  Chip ID: 0xa1=EHF 0xc1=DHG

0x5e:  only on DHG, has bits to enable "current mode" temperature detection and

       critical temperature protection

0x45b: only on EHF, bit 3, vin4 alarm (EHF supports 10 inputs, only 9 on DHG)

0x552: only on EHF, vin4

0x558: only on EHF, vin4 high limit

0x559: only on EHF, vin4 low limit

0x6b:  only on DHG, SYS fan critical temperature

0x6c:  only on DHG, CPU fan0 critical temperature

0x6d:  only on DHG, AUX fan critical temperature

0x6e:  only on DHG, CPU fan1 critical temperature

0x50-0x55 and 0x650-0x657 are marked "Test Register" for the EHF, but "Reserved

       Register" for the DHG

The DHG also supports PECI, where the DHG queries Intel CPU temperatures, and

the ICH8 southbridge gets that data via PECI from the DHG, so that the

southbridge drives the fans. And the DHG supports SST, a one-wire serial bus.