4 This driver supercedes the NCT6775F and NCT6776F support in the W83627EHF
5 driver. It supports NCT6106D, NCT6775F, NCT6776F, NCT6779D, and NCT6791D.
7 The driver is also available in the upstream kernel. This version is maintained
8 for backward compatibility with older kernels. I am trying to keep it buildable
9 for older kernels, but may miss a problem once in a while. If you have a problem
10 compiling this driver with any kernel version 2.6.16 or later, please let me
14 =======================
17 * Nuvoton NCT6102D/NCT6104D/NCT6106D
19 Addresses scanned: ISA address retrieved from Super I/O registers
20 Datasheet: Available from Nuvoton upon request
21 * Nuvoton NCT6775F/W83667HG-I
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 Addresses scanned: ISA address retrieved from Super I/O registers
32 Datasheet: Available from Nuvoton upon request
35 Addresses scanned: ISA address retrieved from Super I/O registers
36 Datasheet: Available from Nuvoton upon request
39 Guenter Roeck <linux@roeck-us.net>
40 David Bartley <andareed@gmail.com> (NCT6791D support)
45 This driver implements support for the Nuvoton NCT6106D, NCT6775F, NCT6776F,
46 NCT6779D, and NCT6791D super I/O chips. We will refer to them collectively as
49 The chips implement up to 8 temperature sensors depending on the chip type and
50 configuration. Temperatures used to control fan speed are reported separately.
51 There are 4 to 5 fan rotation speed sensors, 8 to 15 analog voltage sensors,
52 one VID, alarms with beep warnings (control unimplemented), and some automatic
53 fan regulation strategies (plus manual fan control mode).
55 The temperature sensor sources on all chips are configurable. temp4 and higher
56 attributes are only reported if its temperature source differs from the
57 temperature sources of the already reported temperature sensors.
58 The configured source for each of the temperature sensors is provided
61 Temperatures are measured in degrees Celsius and measurement resolution is
62 either 1 degC or 0.5 degC, depending on the temperature source and
63 configuration. An alarm is triggered when the temperature gets higher than
64 the high limit; it stays on until the temperature falls below the hysteresis
65 value. Alarms are only supported for temp1, temp2, and temp3.
67 Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
68 triggered if the rotation speed has dropped below a programmable limit. Fan
69 readings can be divided by a programmable divider (1, 2, 4, 8, 16, 32, 64 or
70 128) to give the readings more range or accuracy. The driver sets the most
71 suitable fan divisor itself. Some fans might not be present because they
72 share pins with other functions.
74 Voltage sensors (also known as IN sensors) report their values in millivolts.
75 An alarm is triggered if the voltage has crossed a programmable minimum
78 The driver supports automatic fan control mode known as Thermal Cruise.
79 In this mode, the chip attempts to keep the measured temperature in a
80 predefined temperature range. If the temperature goes out of range, fan
81 is driven slower/faster to reach the predefined range again.
83 The mode works for fan1-fan5.
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)
107 Common fan control attributes
108 -----------------------------
110 pwm[1-5]_temp_sel Temperature source. Value is temperature sensor index.
111 For example, select '1' for temp1_input.
112 pwm[1-5]_weight_temp_sel
113 Secondary temperature source. Value is temperature
114 sensor index. For example, select '1' for temp1_input.
115 pwm[1-5]_weight_enable Set to 1 to enable secondary temperature control.
117 If secondary temperature functionality is enabled, it is controlled with the
118 following attributes.
120 pwm[1-5]_weight_duty_step
122 pwm[1-5]_weight_temp_step
123 Temperature step size. With each step over
124 temp_step_base, the value of weight_duty_step is added
125 to the current pwm value.
126 pwm[1-5]_weight_temp_step_base
127 Temperature at which secondary temperature control kicks
129 pwm[1-5]_weight_temp_step_tol
130 Temperature step tolerance or hysteresis. This is a
134 Thermal Cruise mode (2)
135 -----------------------
137 If the temperature is in the range defined by:
139 pwm[1-5]_target Target temperature, unit millidegree Celsius
141 pwm[1-5]_auto_temp1_hyst
142 Hysteresis, unit millidegree Celsius
143 Hysteresis value is relative to pwm[1-5]_auto_temp1.
145 there are no changes to fan speed. Once the temperature leaves the interval,
146 fan speed increases (temp is higher) or decreases if lower than desired,
147 using the following steps and times.
149 pwm[1-5]_start_output fan pwm start value (range 1 - 255), to start fan
150 when the temperature is above defined range.
151 pwm[1-5]_stop_output lowest fan pwm (range 1 - 255) if temperature is below
153 pwm[1-5]_stop_output_enable
154 Set to 1 to enable pwm[1-5]_stop_output. If disabled
155 (set to 0), the fan will stop if the temperature is
156 below the defined range.
157 pwm[1-5]_step_up_time milliseconds [ms] before fan speed is increased
158 pwm[1-5]_step_down_time milliseconds [ms] before fan speed is decreased
159 pwm[1-5]_stop_time how many milliseconds [ms] must elapse to switch
160 corresponding fan off (when the temperature was below
163 Speed Cruise mode (3)
164 ---------------------
166 This modes tries to keep the fan speed constant.
167 Untested; use at your own risk.
169 Smart Fan IV mode (5)
170 ---------------------
172 The fan is regulated to maintain a target temperature. There are five data
173 points. Subsequent data points should be set to higher temperatures and higher
174 pwm values to achieve higher fan speeds with increasing temperature. The last
175 data point reflects critical temperature mode, in which the fans should run at
178 pwm[1-5]_auto_point[1-5]_pwm
179 pwm value to be set if temperature reaches matching
181 pwm[1-5]_auto_point[1-5]_temp
182 Temperature at which the matching pwm is enabled.
183 pwm[1-5]_step_up_time milliseconds [ms] before fan speed is increased
184 pwm[1-5]_step_down_time milliseconds [ms] before fan speed is decreased
185 pwm[1-5]_step_enable Set to 1 to enable fine grain speed control.
186 If disabled, pwm values will increase or decrease to
187 the values configured in the auto_point_pwm attributes.
188 If enabled, pwm values will be interpolated, resulting
189 in a more fine-grained fan control, resulting in a more
190 fine-grained fan control
196 On various ASUS boards with NCT6776F, it appears that CPUTIN is not really
197 connected to anything and floats, or that it is connected to some non-standard
198 temperature measurement device. As a result, the temperature reported on CPUTIN
199 will not reflect a usable value. It often reports unreasonably high
200 temperatures, and in some cases the reported temperature declines if the actual
201 temperature increases (similar to the raw PECI temperature value - see PECI
202 specification for details). CPUTIN should therefore be be ignored on ASUS
203 boards. The CPU temperature on ASUS boards is reported from PECI 0.
205 Also, there have been reports that not all fan speeds are reported on at least
206 some ASUS boards. P9X79 WS is one example, where fan speed is only reported
207 for two of the fans on the board.
209 Note that ASUS does not support Linux on desktop boards (this appears to be
210 official ASUS policy) and does not release board specifications, so there is
211 nothing we can do to improve support for such boards unless we get board
212 specifications or a detailed description on how to control the fans on the
218 After a suspend/resume cycle, all fan control settings are restored to the BIOS