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1Note
2====
3
4This driver supersedes the NCT6775F and NCT6776F support in the W83627EHF
5driver.
6
7Kernel driver NCT6775
8=====================
9
10Supported chips:
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11 * Nuvoton NCT6102D/NCT6104D/NCT6106D
12 Prefix: 'nct6106'
13 Addresses scanned: ISA address retrieved from Super I/O registers
14 Datasheet: Available from the Nuvoton web site
2c7fd30d 15 * Nuvoton NCT5572D/NCT6771F/NCT6772F/NCT6775F/W83677HG-I
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16 Prefix: 'nct6775'
17 Addresses scanned: ISA address retrieved from Super I/O registers
18 Datasheet: Available from Nuvoton upon request
b6e6dd8e 19 * Nuvoton NCT5573D/NCT5577D/NCT6776D/NCT6776F
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20 Prefix: 'nct6776'
21 Addresses scanned: ISA address retrieved from Super I/O registers
22 Datasheet: Available from Nuvoton upon request
2c7fd30d 23 * Nuvoton NCT5532D/NCT6779D
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24 Prefix: 'nct6779'
25 Addresses scanned: ISA address retrieved from Super I/O registers
26 Datasheet: Available from Nuvoton upon request
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27 * Nuvoton NCT6791D
28 Prefix: 'nct6791'
29 Addresses scanned: ISA address retrieved from Super I/O registers
30 Datasheet: Available from Nuvoton upon request
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31
32Authors:
33 Guenter Roeck <linux@roeck-us.net>
34
35Description
36-----------
37
38This driver implements support for the Nuvoton NCT6775F, NCT6776F, and NCT6779D
2c7fd30d 39and compatible super I/O chips.
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40
41The chips support up to 25 temperature monitoring sources. Up to 6 of those are
42direct temperature sensor inputs, the others are special sources such as PECI,
43PCH, and SMBUS. Depending on the chip type, 2 to 6 of the temperature sources
44can be monitored and compared against minimum, maximum, and critical
45temperatures. The driver reports up to 10 of the temperatures to the user.
46There are 4 to 5 fan rotation speed sensors, 8 to 15 analog voltage sensors,
47one VID, alarms with beep warnings (control unimplemented), and some automatic
48fan regulation strategies (plus manual fan control mode).
49
50The temperature sensor sources on all chips are configurable. The configured
51source for each of the temperature sensors is provided in tempX_label.
52
53Temperatures are measured in degrees Celsius and measurement resolution is
54either 1 degC or 0.5 degC, depending on the temperature source and
55configuration. An alarm is triggered when the temperature gets higher than
56the high limit; it stays on until the temperature falls below the hysteresis
57value. Alarms are only supported for temp1 to temp6, depending on the chip type.
58
59Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
60triggered if the rotation speed has dropped below a programmable limit. On
61NCT6775F, fan readings can be divided by a programmable divider (1, 2, 4, 8,
6216, 32, 64 or 128) to give the readings more range or accuracy; the other chips
63do not have a fan speed divider. The driver sets the most suitable fan divisor
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64itself; specifically, it increases the divider value each time a fan speed
65reading returns an invalid value, and it reduces it if the fan speed reading
66is lower than optimal. Some fans might not be present because they share pins
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67with other functions.
68
69Voltage sensors (also known as IN sensors) report their values in millivolts.
70An alarm is triggered if the voltage has crossed a programmable minimum
71or maximum limit.
72
73The driver supports automatic fan control mode known as Thermal Cruise.
74In this mode, the chip attempts to keep the measured temperature in a
75predefined temperature range. If the temperature goes out of range, fan
76is driven slower/faster to reach the predefined range again.
77
78The mode works for fan1-fan5.
79
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80sysfs attributes
81----------------
82
83pwm[1-5] - this file stores PWM duty cycle or DC value (fan speed) in range:
84 0 (lowest speed) to 255 (full)
85
86pwm[1-5]_enable - this file controls mode of fan/temperature control:
87 * 0 Fan control disabled (fans set to maximum speed)
88 * 1 Manual mode, write to pwm[0-5] any value 0-255
89 * 2 "Thermal Cruise" mode
90 * 3 "Fan Speed Cruise" mode
91 * 4 "Smart Fan III" mode (NCT6775F only)
92 * 5 "Smart Fan IV" mode
93
94pwm[1-5]_mode - controls if output is PWM or DC level
95 * 0 DC output
96 * 1 PWM output
97
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98Common fan control attributes
99-----------------------------
100
101pwm[1-5]_temp_sel Temperature source. Value is temperature sensor index.
102 For example, select '1' for temp1_input.
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103pwm[1-5]_weight_temp_sel
104 Secondary temperature source. Value is temperature
105 sensor index. For example, select '1' for temp1_input.
106 Set to 0 to disable secondary temperature control.
107
108If secondary temperature functionality is enabled, it is controlled with the
109following attributes.
110
111pwm[1-5]_weight_duty_step
112 Duty step size.
113pwm[1-5]_weight_temp_step
114 Temperature step size. With each step over
115 temp_step_base, the value of weight_duty_step is added
116 to the current pwm value.
117pwm[1-5]_weight_temp_step_base
118 Temperature at which secondary temperature control kicks
119 in.
120pwm[1-5]_weight_temp_step_tol
121 Temperature step tolerance.
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122
123Thermal Cruise mode (2)
124-----------------------
125
126If the temperature is in the range defined by:
127
128pwm[1-5]_target_temp Target temperature, unit millidegree Celsius
129 (range 0 - 127000)
130pwm[1-5]_temp_tolerance
131 Target temperature tolerance, unit millidegree Celsius
132
133there are no changes to fan speed. Once the temperature leaves the interval, fan
134speed increases (if temperature is higher that desired) or decreases (if
135temperature is lower than desired), using the following limits and time
136intervals.
137
138pwm[1-5]_start fan pwm start value (range 1 - 255), to start fan
139 when the temperature is above defined range.
140pwm[1-5]_floor lowest fan pwm (range 0 - 255) if temperature is below
141 the defined range. If set to 0, the fan is expected to
142 stop if the temperature is below the defined range.
143pwm[1-5]_step_up_time milliseconds before fan speed is increased
144pwm[1-5]_step_down_time milliseconds before fan speed is decreased
145pwm[1-5]_stop_time how many milliseconds must elapse to switch
146 corresponding fan off (when the temperature was below
147 defined range).
148
149Speed Cruise mode (3)
150---------------------
151
152This modes tries to keep the fan speed constant.
153
154fan[1-5]_target Target fan speed
155fan[1-5]_tolerance
156 Target speed tolerance
157
158
159Untested; use at your own risk.
160
161Smart Fan IV mode (5)
162---------------------
163
164This mode offers multiple slopes to control the fan speed. The slopes can be
165controlled by setting the pwm and temperature attributes. When the temperature
166rises, the chip will calculate the DC/PWM output based on the current slope.
167There are up to seven data points depending on the chip type. Subsequent data
168points should be set to higher temperatures and higher pwm values to achieve
169higher fan speeds with increasing temperature. The last data point reflects
170critical temperature mode, in which the fans should run at full speed.
171
172pwm[1-5]_auto_point[1-7]_pwm
173 pwm value to be set if temperature reaches matching
174 temperature range.
175pwm[1-5]_auto_point[1-7]_temp
176 Temperature over which the matching pwm is enabled.
177pwm[1-5]_temp_tolerance
178 Temperature tolerance, unit millidegree Celsius
179pwm[1-5]_crit_temp_tolerance
180 Temperature tolerance for critical temperature,
181 unit millidegree Celsius
182
183pwm[1-5]_step_up_time milliseconds before fan speed is increased
184pwm[1-5]_step_down_time milliseconds before fan speed is decreased
185
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186Usage Notes
187-----------
188
189On various ASUS boards with NCT6776F, it appears that CPUTIN is not really
190connected to anything and floats, or that it is connected to some non-standard
191temperature measurement device. As a result, the temperature reported on CPUTIN
192will not reflect a usable value. It often reports unreasonably high
193temperatures, and in some cases the reported temperature declines if the actual
194temperature increases (similar to the raw PECI temperature value - see PECI
195specification for details). CPUTIN should therefore be be ignored on ASUS
196boards. The CPU temperature on ASUS boards is reported from PECI 0.