Description¶

This driver implements support for the Winbond W83627EHF, W83627EHG,W83627DHG, W83627DHG-P, W83627UHG, W83667HG, W83667HG-B, W83667HG-I(NCT6775F), and NCT6776F super I/O chips. We will refer to them collectivelyas Winbond chips.

The chips implement 3 to 4 temperature sensors (9 for NCT6775F and NCT6776F),2 to 5 fan rotation speed sensors, 8 to 10 analog voltage sensors, one VID(except for 627UHG), alarms with beep warnings (control unimplemented),and some automatic fan regulation strategies (plus manual fan control mode).

The temperature sensor sources on W82677HG-B, NCT6775F, and NCT6776F areconfigurable. temp4 and higher attributes are only reported if its temperaturesource differs from the temperature sources of the already reported temperaturesensors. The configured source for each of the temperature sensors is providedin tempX_label.

Temperatures are measured in degrees Celsius and measurement resolution is 1degC for temp1 and 0.5 degC for temp2 and temp3. For temp4 and higher,resolution is 1 degC for W83667HG-B and 0.0 degC for NCT6775F and NCT6776F.An alarm is triggered when the temperature gets higher than high limit;it stays on until the temperature falls below the hysteresis value.Alarms are only supported for temp1, temp2, and temp3.

Fan rotation speeds are reported in RPM (rotations per minute). An alarm istriggered if the rotation speed has dropped below a programmable limit. Fanreadings can be divided by a programmable divider (1, 2, 4, 8, 16, 32, 64 or128) to give the readings more range or accuracy. The driver sets the mostsuitable fan divisor itself. Some fans might not be present because theyshare 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 minimumor 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 apredefined temperature range. If the temperature goes out of range, fanis driven slower/faster to reach the predefined range again.

The mode works for fan1-fan4. Mapping of temperatures to pwm outputs is asfollows:

temp1 -> pwm1temp2 -> pwm2temp3 -> pwm3 (not on 627UHG)prog  -> pwm4 (not on 667HG and 667HG-B; the programmable setting is not               supported by the driver)

/sys files¶

name

this is a standard hwmon device entry, it contains the name ofthe device (see the prefix in the list of supported devices atthe top of this file)

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” mode
• 3 “Fan Speed Cruise” mode
• 4 “Smart Fan III” mode
• 5 “Smart Fan IV” mode

SmartFan III mode is not supported on NCT6776F.

SmartFan IV mode is configurable only if it was configured at systemstartup, and is only supported for W83677HG-B, NCT6775F, and NCT6776F.SmartFan IV operational parameters can not be configured at this time,and the various pwm attributes are not used in SmartFan IV mode.The attributes can be written to, which is useful if you plan toconfigure the system for a different pwm mode. However, the informationreturned when reading pwm attributes is unrelated to SmartFan IVoperation.

pwm[1-4]_mode

controls if output is PWM or DC level

• 0 DC output (0 - 12v)
• 1 PWM output

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 temperatureis below defined range.

pwm[1-4]_stop_time

how many milliseconds [ms] must elapse to switchcorresponding fan off. (when the temperature was belowdefined range).

pwm[1-4]_start_output

minimum fan speed (range 1 - 255) when spinning up

pwm[1-4]_step_output

rate of fan speed change (1 - 255)

pwm[1-4]_stop_output

minimum fan speed (range 1 - 255) when spinning down

pwm[1-4]_max_output

maximum fan speed (range 1 - 255), when the temperatureis above defined range.

Note: last six 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 havedifferent functions on the 627EHF and the 627DHG. Some registers also havedifferent power-on default values, but BIOS should already be loadingappropriate defaults. Note that bank selection must be performed as is currentlydone in the driver for all register addresses.

The DHG also supports PECI, where the DHG queries Intel CPU temperatures, andthe ICH8 southbridge gets that data via PECI from the DHG, so that thesouthbridge drives the fans. And the DHG supports SST, a one-wire serial bus.

The DHG-P has an additional automatic fan speed control mode named Smart Fan(TM) III+. This mode is not yet supported by the driver.