Note ==== This driver is experimental and has only been tested on NCT6775F and NCT6776F. ABI (sysfs attribute support) is not final and is expected to change repeatedly before the driver is stable. Until then, please feel free to provide your input. This driver supercedes the NCT6775F and NCT6776F support in the W83627EHF driver. Kernel driver NCT6775 ======================= Supported chips: * Nuvoton NCT6775F/W83667HG-I Prefix: 'nct6775' Addresses scanned: ISA address retrieved from Super I/O registers Datasheet: Available from Nuvoton upon request * Nuvoton NCT6776F Prefix: 'nct6776' Addresses scanned: ISA address retrieved from Super I/O registers Datasheet: Available from Nuvoton upon request * Nuvoton NCT6779D Prefix: 'nct6779' Addresses scanned: ISA address retrieved from Super I/O registers Datasheet: Available from Nuvoton upon request Authors: Guenter Roeck Description ----------- This driver implements support for the Nuvoton NCT6775F, NCT6776F, and NCT6779D super I/O chips. We will refer to them collectively as Nuvoton chips. The chips implement up to 8 temperature sensors depending on the chip type and configuration. Temperatures used to control fan speed are reported separately. There are 4 to 5 fan rotation speed sensors, 8 to 15 analog voltage sensors, one VID, alarms with beep warnings (control unimplemented), and some automatic fan regulation strategies (plus manual fan control mode). The temperature sensor sources on all chips are configurable. temp4 and higher attributes are only reported if its temperature source differs from the temperature sources of the already reported temperature sensors. The configured source for each of the temperature sensors is provided in tempX_label. Temperatures are measured in degrees Celsius and measurement resolution is either 1 degC or 0.5 degC, depending on the temperature source and configuration. An alarm is triggered when the temperature gets higher than the 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 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-fan5. The temperature source used to control pwm1..pwm5 can be configured with pwm[1..5]_temp_sel and pwm[1..5]_weight_temp_sel. The value reported and configured with those attributes is the temperature sensor attribute index. For example, to map the source of temp1_input to pwm1_temp_sel, write 1 into the pwm1_temp_sel attribute. /sys files ---------- name - this is a standard hwmon device entry, it contains the name of the device (see the prefix in the list of supported devices at the top of this file) pwm[1-5] - this file stores PWM duty cycle or DC value (fan speed) in range: 0 (stop) to 255 (full) pwm[1-5]_enable - this file controls mode of fan/temperature control: * 0 Fan control disabled (fans set to maximum speed) * 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 (NCT6775F only) * 5 "Smart Fan IV" mode pwm[1-5]_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[1-5]_target Target temperature, unit millidegree Celsius (range 0 - 127000) pwm[1-5]_auto_temp1_hyst Hysteresis, unit millidegree Celsius Hysteresis value is relative to pwm[1-5]_auto_temp1. 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, using the following steps and times. pwm[1-5]_start_output fan pwm start value (range 1 - 255), to start fan when the temperature is above defined range. pwm[1-5]_stop_output fan pwm (range 1 - 255) to stop fan. pwm[1-5]_step_up_time milliseconds [ms] before fan speed is increased pwm[1-5]_step_down_time milliseconds [ms] before fan speed is decreased pwm[1-5]_stop_time how many milliseconds [ms] must elapse to switch corresponding fan off. (when the temperature was below defined range). Speed Cruise mode ----------------- This modes tries to keep the fan speed constant. Untested; use at your own risk. Usage Notes ----------- On various ASUS boards, it appears that CPUTIN is not really connected to anything and floats, or that it is connected to some non-standard temperature measurement device. As a result, the temperature reported on CPUTIN will not reflect a usable value. It often reports unreasonablyy high temperatures, and in some cases the reported temperature declines if the actual temperature increases. CPUTIN should therefore be be ignored on ASUS boards. The CPU temperature on ASUS boards is reported from PECI 0. Implementation Details ---------------------- TBD