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- Note
- ====
- This driver supersedes 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 <linux@roeck-us.net>
- Description
- -----------
- This driver implements support for the Nuvoton NCT6775F, NCT6776F, and NCT6779D
- 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.
- 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.
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