4 This driver is experimental and has only been tested on NCT6775F.
6 ABI (sysfs attribute support) is not final and is expected to change
7 repeatedly before the driver is stable. Until then, please feel free
10 This driver supercedes the NCT6775F and NCT6776F support in the W83627EHF
14 =======================
17 * Nuvoton NCT6775F/W83667HG-I
19 Addresses scanned: ISA address retrieved from Super I/O registers
20 Datasheet: Available from Nuvoton upon request
23 Addresses scanned: ISA address retrieved from Super I/O registers
24 Datasheet: Available from Nuvoton upon request
27 Addresses scanned: ISA address retrieved from Super I/O registers
28 Datasheet: Available from Nuvoton upon request
31 Guenter Roeck <linux@roeck-us.net>
36 This driver implements support for the Nuvoton NCT6775F, NCT6776F, and NCT6779D
37 super I/O chips. We will refer to them collectively as Nuvoton chips.
39 The chips implement 2 to 4 temperature sensors (9 for NCT6775F and NCT6776F),
40 2 to 5 fan rotation speed sensors, 8 to 15 analog voltage sensors, one VID,
41 alarms with beep warnings (control unimplemented), and some automatic fan
42 regulation strategies (plus manual fan control mode).
44 The temperature sensor sources on all chips are configurable. temp4 and higher
45 attributes are only reported if its temperature source differs from the
46 temperature sources of the already reported temperature sensors.
47 The configured source for each of the temperature sensors is provided
50 Temperatures are measured in degrees Celsius and measurement resolution is 1
51 degC for temp1 and and 0.5 degC for temp2 and temp3. For temp4 and higher,
52 resolution is 1 degC for W83667HG-B and 0.5 degC for NCT6775F and NCT6776F.
53 An alarm is triggered when the temperature gets higher than high limit;
54 it stays on until the temperature falls below the hysteresis value.
55 Alarms are only supported for temp1, temp2, and temp3.
57 Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
58 triggered if the rotation speed has dropped below a programmable limit. Fan
59 readings can be divided by a programmable divider (1, 2, 4, 8, 16, 32, 64 or
60 128) to give the readings more range or accuracy. The driver sets the most
61 suitable fan divisor itself. Some fans might not be present because they
62 share pins with other functions.
64 Voltage sensors (also known as IN sensors) report their values in millivolts.
65 An alarm is triggered if the voltage has crossed a programmable minimum
68 The driver supports automatic fan control mode known as Thermal Cruise.
69 In this mode, the chip attempts to keep the measured temperature in a
70 predefined temperature range. If the temperature goes out of range, fan
71 is driven slower/faster to reach the predefined range again.
73 The mode works for fan1-fan4. Mapping of temperatures to pwm outputs is as
83 name - this is a standard hwmon device entry, it contains the name of
84 the device (see the prefix in the list of supported devices at
87 pwm[1-5] - this file stores PWM duty cycle or DC value (fan speed) in range:
88 0 (stop) to 255 (full)
90 pwm[1-5]_enable - this file controls mode of fan/temperature control:
91 * 0 Fan control disabled (fans set to maximum speed)
92 * 1 Manual mode, write to pwm file any value 0-255 (full speed)
93 * 2 "Thermal Cruise" mode
94 * 3 "Fan Speed Cruise" mode
95 * 4 "Smart Fan IV" mode
97 SmartFan III mode is not supported by the driver.
99 pwm[1-5]_mode - controls if output is PWM or DC level
100 * 0 DC output (0 - 12v)
106 If the temperature is in the range defined by:
108 pwm[1-5]_target Target temperature, unit millidegree Celsius
110 pwm[1-5]_auto_temp1_hyst
111 Hysteresis, unit millidegree Celsius
112 Hysteresis value is relative to pwm[1-5]_auto_temp1.
114 there are no changes to fan speed. Once the temperature leaves the interval,
115 fan speed increases (temp is higher) or decreases if lower than desired,
116 using the following steps and times.
118 pwm[1-5]_start_output fan pwm start value (range 1 - 255), to start fan
119 when the temperature is above defined range.
120 pwm[1-5]_stop_output fan pwm (range 1 - 255) to stop fan.
121 pwm[1-5]_step_up_time milliseconds [ms] before fan speed is increased
122 pwm[1-5]_step_down_time milliseconds [ms] before fan speed is decreased
123 pwm[1-5]_stop_time how many milliseconds [ms] must elapse to switch
124 corresponding fan off. (when the temperature was below
130 This modes tries to keep the fan speed constant.
131 Untested; use at your own risk.
132 Support may be removed in a later version of the driver.
135 Implementation Details
136 ----------------------