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diff --git a/Documentation/hwmon/nct6775 b/Documentation/hwmon/nct6775 new file mode 100644 index 000000000000..4e9ef60e8c6c --- /dev/null +++ b/Documentation/hwmon/nct6775 @@ -0,0 +1,188 @@ +Note +==== + +This driver supersedes the NCT6775F and NCT6776F support in the W83627EHF +driver. + +Kernel driver NCT6775 +===================== + +Supported chips: + * Nuvoton NCT5572D/NCT6771F/NCT6772F/NCT6775F/W83677HG-I + Prefix: 'nct6775' + Addresses scanned: ISA address retrieved from Super I/O registers + Datasheet: Available from Nuvoton upon request + * Nuvoton NCT5577D/NCT6776D/NCT6776F + Prefix: 'nct6776' + Addresses scanned: ISA address retrieved from Super I/O registers + Datasheet: Available from Nuvoton upon request + * Nuvoton NCT5532D/NCT6779D + Prefix: 'nct6779' + Addresses scanned: ISA address retrieved from Super I/O registers + Datasheet: Available from Nuvoton upon request + +Authors: + Guenter Roeck <linux@roeck-us.net> + +Description +----------- + +This driver implements support for the Nuvoton NCT6775F, NCT6776F, and NCT6779D +and compatible super I/O chips. + +The chips support up to 25 temperature monitoring sources. Up to 6 of those are +direct temperature sensor inputs, the others are special sources such as PECI, +PCH, and SMBUS. Depending on the chip type, 2 to 6 of the temperature sources +can be monitored and compared against minimum, maximum, and critical +temperatures. The driver reports up to 10 of the temperatures to the user. +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. 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 to temp6, depending on the chip type. + +Fan rotation speeds are reported in RPM (rotations per minute). An alarm is +triggered if the rotation speed has dropped below a programmable limit. On +NCT6775F, 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 other chips +do not have a fan speed divider. The driver sets the most suitable fan divisor +itself; specifically, it increases the divider value each time a fan speed +reading returns an invalid value, and it reduces it if the fan speed reading +is lower than optimal. 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. + +sysfs attributes +---------------- + +pwm[1-5] - this file stores PWM duty cycle or DC value (fan speed) in range: + 0 (lowest speed) 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[0-5] any value 0-255 + * 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 + * 1 PWM output + +Common fan control attributes +----------------------------- + +pwm[1-5]_temp_sel Temperature source. Value is temperature sensor index. + For example, select '1' for temp1_input. +pwm[1-5]_weight_temp_sel + Secondary temperature source. Value is temperature + sensor index. For example, select '1' for temp1_input. + Set to 0 to disable secondary temperature control. + +If secondary temperature functionality is enabled, it is controlled with the +following attributes. + +pwm[1-5]_weight_duty_step + Duty step size. +pwm[1-5]_weight_temp_step + Temperature step size. With each step over + temp_step_base, the value of weight_duty_step is added + to the current pwm value. +pwm[1-5]_weight_temp_step_base + Temperature at which secondary temperature control kicks + in. +pwm[1-5]_weight_temp_step_tol + Temperature step tolerance. + +Thermal Cruise mode (2) +----------------------- + +If the temperature is in the range defined by: + +pwm[1-5]_target_temp Target temperature, unit millidegree Celsius + (range 0 - 127000) +pwm[1-5]_temp_tolerance + Target temperature tolerance, unit millidegree Celsius + +there are no changes to fan speed. Once the temperature leaves the interval, fan +speed increases (if temperature is higher that desired) or decreases (if +temperature is lower than desired), using the following limits and time +intervals. + +pwm[1-5]_start fan pwm start value (range 1 - 255), to start fan + when the temperature is above defined range. +pwm[1-5]_floor lowest fan pwm (range 0 - 255) if temperature is below + the defined range. If set to 0, the fan is expected to + stop if the temperature is below the defined range. +pwm[1-5]_step_up_time milliseconds before fan speed is increased +pwm[1-5]_step_down_time milliseconds before fan speed is decreased +pwm[1-5]_stop_time how many milliseconds must elapse to switch + corresponding fan off (when the temperature was below + defined range). + +Speed Cruise mode (3) +--------------------- + +This modes tries to keep the fan speed constant. + +fan[1-5]_target Target fan speed +fan[1-5]_tolerance + Target speed tolerance + + +Untested; use at your own risk. + +Smart Fan IV mode (5) +--------------------- + +This mode offers multiple slopes to control the fan speed. The slopes can be +controlled by setting the pwm and temperature attributes. When the temperature +rises, the chip will calculate the DC/PWM output based on the current slope. +There are up to seven data points depending on the chip type. Subsequent data +points should be set to higher temperatures and higher pwm values to achieve +higher fan speeds with increasing temperature. The last data point reflects +critical temperature mode, in which the fans should run at full speed. + +pwm[1-5]_auto_point[1-7]_pwm + pwm value to be set if temperature reaches matching + temperature range. +pwm[1-5]_auto_point[1-7]_temp + Temperature over which the matching pwm is enabled. +pwm[1-5]_temp_tolerance + Temperature tolerance, unit millidegree Celsius +pwm[1-5]_crit_temp_tolerance + Temperature tolerance for critical temperature, + unit millidegree Celsius + +pwm[1-5]_step_up_time milliseconds before fan speed is increased +pwm[1-5]_step_down_time milliseconds before fan speed is decreased + +Usage Notes +----------- + +On various ASUS boards with NCT6776F, 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 unreasonably high +temperatures, and in some cases the reported temperature declines if the actual +temperature increases (similar to the raw PECI temperature value - see PECI +specification for details). CPUTIN should therefore be be ignored on ASUS +boards. The CPU temperature on ASUS boards is reported from PECI 0. |