170 lines
6.6 KiB
Plaintext
170 lines
6.6 KiB
Plaintext
Note
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====
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This driver supersedes the NCT6775F and NCT6776F support in the W83627EHF
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driver.
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Kernel driver NCT6775
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=====================
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Supported chips:
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* Nuvoton NCT6775F/W83667HG-I
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Prefix: 'nct6775'
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Addresses scanned: ISA address retrieved from Super I/O registers
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Datasheet: Available from Nuvoton upon request
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* Nuvoton NCT6776F
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Prefix: 'nct6776'
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Addresses scanned: ISA address retrieved from Super I/O registers
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Datasheet: Available from Nuvoton upon request
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* Nuvoton NCT6779D
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Prefix: 'nct6779'
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Addresses scanned: ISA address retrieved from Super I/O registers
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Datasheet: Available from Nuvoton upon request
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Authors:
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Guenter Roeck <linux@roeck-us.net>
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Description
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-----------
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This driver implements support for the Nuvoton NCT6775F, NCT6776F, and NCT6779D
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super I/O chips.
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The chips support up to 25 temperature monitoring sources. Up to 6 of those are
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direct temperature sensor inputs, the others are special sources such as PECI,
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PCH, and SMBUS. Depending on the chip type, 2 to 6 of the temperature sources
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can be monitored and compared against minimum, maximum, and critical
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temperatures. The driver reports up to 10 of the temperatures to the user.
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There are 4 to 5 fan rotation speed sensors, 8 to 15 analog voltage sensors,
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one VID, alarms with beep warnings (control unimplemented), and some automatic
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fan regulation strategies (plus manual fan control mode).
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The temperature sensor sources on all chips are configurable. The configured
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source for each of the temperature sensors is provided in tempX_label.
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Temperatures are measured in degrees Celsius and measurement resolution is
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either 1 degC or 0.5 degC, depending on the temperature source and
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configuration. An alarm is triggered when the temperature gets higher than
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the high limit; it stays on until the temperature falls below the hysteresis
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value. Alarms are only supported for temp1 to temp6, depending on the chip type.
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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. On
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NCT6775F, fan readings can be divided by a programmable divider (1, 2, 4, 8,
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16, 32, 64 or 128) to give the readings more range or accuracy; the other chips
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do not have a fan speed divider. The driver sets the most suitable fan divisor
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itself; specifically, it increases the divider value each time a fan speed
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reading returns an invalid value, and it reduces it if the fan speed reading
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is lower than optimal. Some fans might not be present because they share pins
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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-fan5.
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sysfs attributes
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----------------
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pwm[1-5] - this file stores PWM duty cycle or DC value (fan speed) in range:
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0 (lowest speed) to 255 (full)
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pwm[1-5]_enable - this file controls mode of fan/temperature control:
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* 0 Fan control disabled (fans set to maximum speed)
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* 1 Manual mode, write to pwm[0-5] any value 0-255
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* 2 "Thermal Cruise" mode
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* 3 "Fan Speed Cruise" mode
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* 4 "Smart Fan III" mode (NCT6775F only)
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* 5 "Smart Fan IV" mode
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pwm[1-5]_mode - controls if output is PWM or DC level
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* 0 DC output
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* 1 PWM output
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Common fan control attributes
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-----------------------------
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pwm[1-5]_temp_sel Temperature source. Value is temperature sensor index.
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For example, select '1' for temp1_input.
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Thermal Cruise mode (2)
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-----------------------
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If the temperature is in the range defined by:
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pwm[1-5]_target_temp Target temperature, unit millidegree Celsius
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(range 0 - 127000)
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pwm[1-5]_temp_tolerance
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Target temperature tolerance, unit millidegree Celsius
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there are no changes to fan speed. Once the temperature leaves the interval, fan
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speed increases (if temperature is higher that desired) or decreases (if
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temperature is lower than desired), using the following limits and time
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intervals.
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pwm[1-5]_start fan pwm start value (range 1 - 255), to start fan
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when the temperature is above defined range.
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pwm[1-5]_floor lowest fan pwm (range 0 - 255) if temperature is below
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the defined range. If set to 0, the fan is expected to
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stop if the temperature is below the defined range.
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pwm[1-5]_step_up_time milliseconds before fan speed is increased
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pwm[1-5]_step_down_time milliseconds before fan speed is decreased
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pwm[1-5]_stop_time how many milliseconds 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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Speed Cruise mode (3)
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---------------------
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This modes tries to keep the fan speed constant.
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fan[1-5]_target Target fan speed
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fan[1-5]_tolerance
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Target speed tolerance
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Untested; use at your own risk.
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Smart Fan IV mode (5)
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---------------------
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This mode offers multiple slopes to control the fan speed. The slopes can be
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controlled by setting the pwm and temperature attributes. When the temperature
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rises, the chip will calculate the DC/PWM output based on the current slope.
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There are up to seven data points depending on the chip type. Subsequent data
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points should be set to higher temperatures and higher pwm values to achieve
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higher fan speeds with increasing temperature. The last data point reflects
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critical temperature mode, in which the fans should run at full speed.
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pwm[1-5]_auto_point[1-7]_pwm
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pwm value to be set if temperature reaches matching
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temperature range.
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pwm[1-5]_auto_point[1-7]_temp
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Temperature over which the matching pwm is enabled.
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pwm[1-5]_temp_tolerance
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Temperature tolerance, unit millidegree Celsius
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pwm[1-5]_crit_temp_tolerance
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Temperature tolerance for critical temperature,
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unit millidegree Celsius
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pwm[1-5]_step_up_time milliseconds before fan speed is increased
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pwm[1-5]_step_down_time milliseconds before fan speed is decreased
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Usage Notes
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-----------
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On various ASUS boards with NCT6776F, it appears that CPUTIN is not really
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connected to anything and floats, or that it is connected to some non-standard
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temperature measurement device. As a result, the temperature reported on CPUTIN
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will not reflect a usable value. It often reports unreasonably high
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temperatures, and in some cases the reported temperature declines if the actual
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temperature increases (similar to the raw PECI temperature value - see PECI
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specification for details). CPUTIN should therefore be be ignored on ASUS
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boards. The CPU temperature on ASUS boards is reported from PECI 0.
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