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.
75 The temperature source used to control pwm1..pwm5 can be configured with
76 pwm[1..5]_temp_sel and pwm[1..5]_weight_temp_sel. The value reported and
77 configured with those attributes is the temperature sensor attribute index.
78 For example, to map the source of temp1_input to pwm1_temp_sel, write 1
79 into the pwm1_temp_sel attribute.
84 name - this is a standard hwmon device entry, it contains the name of
85 the device (see the prefix in the list of supported devices at
88 pwm[1-5] - this file stores PWM duty cycle or DC value (fan speed) in range:
89 0 (stop) to 255 (full)
91 pwm[1-5]_enable - this file controls mode of fan/temperature control:
92 * 0 Fan control disabled (fans set to maximum speed)
93 * 1 Manual mode, write to pwm file any value 0-255 (full speed)
94 * 2 "Thermal Cruise" mode
95 * 3 "Fan Speed Cruise" mode
96 * 4 "Smart Fan III" mode (NCT6775F only)
97 * 5 "Smart Fan IV" mode
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.
137 On various ASUS boards, it appears that CPUTIN is not really connected to
138 anything and floats, or that it is connected to some non-standard temperature
139 measurement device. As a result, the temperature reported on CPUTIN will not
140 reflect a usable value. It often reports unreasonablyy high temperatures, and in
141 some cases the reported temperature declines if the actual temperature
143 CPUTIN should therefore be be ignored on ASUS boards. The CPU temperature
144 on ASUS boards is reported from PECI 0.
147 Implementation Details
148 ----------------------