4 This driver supercedes the NCT6775F and NCT6776F support in the W83627EHF
5 driver. It supports NCT6106D, NCT6775F, NCT6776F, NCT6779D, NCT6791D, and
8 The driver is also available in the upstream kernel. This version is maintained
9 for backward compatibility with older kernels. I am trying to keep it buildable
10 for older kernels, but may miss a problem once in a while. If you have a problem
11 compiling this driver with any kernel version 2.6.32 or later, please let me
15 =======================
18 * Nuvoton NCT6102D/NCT6104D/NCT6106D
20 Addresses scanned: ISA address retrieved from Super I/O registers
21 Datasheet: Available from Nuvoton upon request
22 * Nuvoton NCT6775F/W83667HG-I
24 Addresses scanned: ISA address retrieved from Super I/O registers
25 Datasheet: Available from Nuvoton upon request
28 Addresses scanned: ISA address retrieved from Super I/O registers
29 Datasheet: Available from Nuvoton upon request
32 Addresses scanned: ISA address retrieved from Super I/O registers
33 Datasheet: Available from Nuvoton upon request
36 Addresses scanned: ISA address retrieved from Super I/O registers
37 Datasheet: Available from Nuvoton upon request
40 Addresses scanned: ISA address retrieved from Super I/O registers
41 Datasheet: Available from Nuvoton upon request
44 Guenter Roeck <linux@roeck-us.net>
45 David Bartley <andareed@gmail.com> (NCT6791D support)
50 This driver implements support for the Nuvoton NCT6106D, NCT6775F, NCT6776F,
51 NCT6779D, NCT6791D, and NCT6792D super I/O chips. We will refer to them
52 collectively as Nuvoton chips.
54 The chips implement up to 8 temperature sensors depending on the chip type and
55 configuration. Temperatures used to control fan speed are reported separately.
56 There are 4 to 5 fan rotation speed sensors, 8 to 15 analog voltage sensors,
57 one VID, alarms with beep warnings (control unimplemented), and some automatic
58 fan regulation strategies (plus manual fan control mode).
60 The temperature sensor sources on all chips are configurable. temp4 and higher
61 attributes are only reported if its temperature source differs from the
62 temperature sources of the already reported temperature sensors.
63 The configured source for each of the temperature sensors is provided
66 Temperatures are measured in degrees Celsius and measurement resolution is
67 either 1 degC or 0.5 degC, depending on the temperature source and
68 configuration. An alarm is triggered when the temperature gets higher than
69 the high limit; it stays on until the temperature falls below the hysteresis
70 value. Alarms are only supported for temp1, temp2, and temp3.
72 Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
73 triggered if the rotation speed has dropped below a programmable limit. Fan
74 readings can be divided by a programmable divider (1, 2, 4, 8, 16, 32, 64 or
75 128) to give the readings more range or accuracy. The driver sets the most
76 suitable fan divisor itself. Some fans might not be present because they
77 share pins with other functions.
79 Voltage sensors (also known as IN sensors) report their values in millivolts.
80 An alarm is triggered if the voltage has crossed a programmable minimum
83 The driver supports automatic fan control mode known as Thermal Cruise.
84 In this mode, the chip attempts to keep the measured temperature in a
85 predefined temperature range. If the temperature goes out of range, fan
86 is driven slower/faster to reach the predefined range again.
88 The mode works for fan1-fan5.
93 name - this is a standard hwmon device entry, it contains the name of
94 the device (see the prefix in the list of supported devices at
97 pwm[1-5] - this file stores PWM duty cycle or DC value (fan speed) in range:
98 0 (stop) to 255 (full)
100 pwm[1-5]_enable - this file controls mode of fan/temperature control:
101 * 0 Fan control disabled (fans set to maximum speed)
102 * 1 Manual mode, write to pwm file any value 0-255 (full speed)
103 * 2 "Thermal Cruise" mode
104 * 3 "Fan Speed Cruise" mode
105 * 4 "Smart Fan III" mode (NCT6775F only)
106 * 5 "Smart Fan IV" mode
108 pwm[1-5]_mode - controls if output is PWM or DC level
109 * 0 DC output (0 - 12v)
112 Common fan control attributes
113 -----------------------------
115 pwm[1-5]_temp_sel Temperature source. Value is temperature sensor index.
116 For example, select '1' for temp1_input.
117 pwm[1-5]_weight_temp_sel
118 Secondary temperature source. Value is temperature
119 sensor index. For example, select '1' for temp1_input.
120 pwm[1-5]_weight_enable Set to 1 to enable secondary temperature control.
122 If secondary temperature functionality is enabled, it is controlled with the
123 following attributes.
125 pwm[1-5]_weight_duty_step
127 pwm[1-5]_weight_temp_step
128 Temperature step size. With each step over
129 temp_step_base, the value of weight_duty_step is added
130 to the current pwm value.
131 pwm[1-5]_weight_temp_step_base
132 Temperature at which secondary temperature control kicks
134 pwm[1-5]_weight_temp_step_tol
135 Temperature step tolerance or hysteresis. This is a
139 Thermal Cruise mode (2)
140 -----------------------
142 If the temperature is in the range defined by:
144 pwm[1-5]_target Target temperature, unit millidegree Celsius
146 pwm[1-5]_auto_temp1_hyst
147 Hysteresis, unit millidegree Celsius
148 Hysteresis value is relative to pwm[1-5]_auto_temp1.
150 there are no changes to fan speed. Once the temperature leaves the interval,
151 fan speed increases (temp is higher) or decreases if lower than desired,
152 using the following steps and times.
154 pwm[1-5]_start_output fan pwm start value (range 1 - 255), to start fan
155 when the temperature is above defined range.
156 pwm[1-5]_stop_output lowest fan pwm (range 1 - 255) if temperature is below
158 pwm[1-5]_stop_output_enable
159 Set to 1 to enable pwm[1-5]_stop_output. If disabled
160 (set to 0), the fan will stop if the temperature is
161 below the defined range.
162 pwm[1-5]_step_up_time milliseconds [ms] before fan speed is increased
163 pwm[1-5]_step_down_time milliseconds [ms] before fan speed is decreased
164 pwm[1-5]_stop_time how many milliseconds [ms] must elapse to switch
165 corresponding fan off (when the temperature was below
168 Speed Cruise mode (3)
169 ---------------------
171 This modes tries to keep the fan speed constant.
172 Untested; use at your own risk.
174 Smart Fan IV mode (5)
175 ---------------------
177 The fan is regulated to maintain a target temperature. There are five data
178 points. Subsequent data points should be set to higher temperatures and higher
179 pwm values to achieve higher fan speeds with increasing temperature. The last
180 data point reflects critical temperature mode, in which the fans should run at
183 pwm[1-5]_auto_point[1-5]_pwm
184 pwm value to be set if temperature reaches matching
186 pwm[1-5]_auto_point[1-5]_temp
187 Temperature at which the matching pwm is enabled.
188 pwm[1-5]_step_up_time milliseconds [ms] before fan speed is increased
189 pwm[1-5]_step_down_time milliseconds [ms] before fan speed is decreased
195 On various ASUS boards with NCT6776F, it appears that CPUTIN is not really
196 connected to anything and floats, or that it is connected to some non-standard
197 temperature measurement device. As a result, the temperature reported on CPUTIN
198 will not reflect a usable value. It often reports unreasonably high
199 temperatures, and in some cases the reported temperature declines if the actual
200 temperature increases (similar to the raw PECI temperature value - see PECI
201 specification for details). CPUTIN should therefore be be ignored on ASUS
202 boards. The CPU temperature on ASUS boards is reported from PECI 0.
204 Also, there have been reports that not all fan speeds are reported on at least
205 some ASUS boards. P9X79 WS is one example, where fan speed is only reported
206 for two of the fans on the board.
208 Note that ASUS does not support Linux on desktop boards (this appears to be
209 official ASUS policy) and does not release board specifications, so there is
210 nothing we can do to improve support for such boards unless we get board
211 specifications or a detailed description on how to control the fans on the
217 After a suspend/resume cycle, all fan control settings are restored to the BIOS