4 This driver is experimental and has only been tested on NCT6775F and NCT6776F.
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 up to 8 temperature sensors depending on the chip type and
40 configuration. Temperatures used to control fan speed are reported separately.
41 There are 4 to 5 fan rotation speed sensors, 8 to 15 analog voltage sensors,
42 one VID, alarms with beep warnings (control unimplemented), and some automatic
43 fan regulation strategies (plus manual fan control mode).
45 The temperature sensor sources on all chips are configurable. temp4 and higher
46 attributes are only reported if its temperature source differs from the
47 temperature sources of the already reported temperature sensors.
48 The configured source for each of the temperature sensors is provided
51 Temperatures are measured in degrees Celsius and measurement resolution is
52 either 1 degC or 0.5 degC, depending on the temperature source and
53 configuration. An alarm is triggered when the temperature gets higher than
54 the high limit; it stays on until the temperature falls below the hysteresis
55 value. 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-fan5. Mapping of temperatures to pwm outputs is as
79 temp14 -> pwm4 (NCT6779D only)
80 temp15 -> pwm5 (NCT6779D only)
82 The temperature source used to control pwm1..pwm5 (temp11..temp15) can be
83 configured with pwm[1..5]_temp_sel.
88 name - this is a standard hwmon device entry, it contains the name of
89 the device (see the prefix in the list of supported devices at
92 pwm[1-5] - this file stores PWM duty cycle or DC value (fan speed) in range:
93 0 (stop) to 255 (full)
95 pwm[1-5]_enable - this file controls mode of fan/temperature control:
96 * 0 Fan control disabled (fans set to maximum speed)
97 * 1 Manual mode, write to pwm file any value 0-255 (full speed)
98 * 2 "Thermal Cruise" mode
99 * 3 "Fan Speed Cruise" mode
100 * 4 "Smart Fan III" mode (NCT6775F only)
101 * 5 "Smart Fan IV" mode
103 pwm[1-5]_mode - controls if output is PWM or DC level
104 * 0 DC output (0 - 12v)
110 If the temperature is in the range defined by:
112 pwm[1-5]_target Target temperature, unit millidegree Celsius
114 pwm[1-5]_auto_temp1_hyst
115 Hysteresis, unit millidegree Celsius
116 Hysteresis value is relative to pwm[1-5]_auto_temp1.
118 there are no changes to fan speed. Once the temperature leaves the interval,
119 fan speed increases (temp is higher) or decreases if lower than desired,
120 using the following steps and times.
122 pwm[1-5]_start_output fan pwm start value (range 1 - 255), to start fan
123 when the temperature is above defined range.
124 pwm[1-5]_stop_output fan pwm (range 1 - 255) to stop fan.
125 pwm[1-5]_step_up_time milliseconds [ms] before fan speed is increased
126 pwm[1-5]_step_down_time milliseconds [ms] before fan speed is decreased
127 pwm[1-5]_stop_time how many milliseconds [ms] must elapse to switch
128 corresponding fan off. (when the temperature was below
134 This modes tries to keep the fan speed constant.
135 Untested; use at your own risk.
138 Implementation Details
139 ----------------------