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Based on kernel version 4.7.2. Page generated on 2016-08-22 22:46 EST.

1	Note
2	====
3	
4	This driver supersedes the NCT6775F and NCT6776F support in the W83627EHF
5	driver.
6	
7	Kernel driver NCT6775
8	=====================
9	
10	Supported chips:
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
15	  * Nuvoton NCT5572D/NCT6771F/NCT6772F/NCT6775F/W83677HG-I
16	    Prefix: 'nct6775'
17	    Addresses scanned: ISA address retrieved from Super I/O registers
18	    Datasheet: Available from Nuvoton upon request
19	  * Nuvoton NCT5573D/NCT5577D/NCT6776D/NCT6776F
20	    Prefix: 'nct6776'
21	    Addresses scanned: ISA address retrieved from Super I/O registers
22	    Datasheet: Available from Nuvoton upon request
23	  * Nuvoton NCT5532D/NCT6779D
24	    Prefix: 'nct6779'
25	    Addresses scanned: ISA address retrieved from Super I/O registers
26	    Datasheet: Available from Nuvoton upon request
27	  * Nuvoton NCT6791D
28	    Prefix: 'nct6791'
29	    Addresses scanned: ISA address retrieved from Super I/O registers
30	    Datasheet: Available from Nuvoton upon request
31	  * Nuvoton NCT6792D
32	    Prefix: 'nct6792'
33	    Addresses scanned: ISA address retrieved from Super I/O registers
34	    Datasheet: Available from Nuvoton upon request
35	  * Nuvoton NCT6793D
36	    Prefix: 'nct6793'
37	    Addresses scanned: ISA address retrieved from Super I/O registers
38	    Datasheet: Available from Nuvoton upon request
39	
40	Authors:
41	        Guenter Roeck <linux@roeck-us.net>
42	
43	Description
44	-----------
45	
46	This driver implements support for the Nuvoton NCT6775F, NCT6776F, and NCT6779D
47	and compatible super I/O chips.
48	
49	The chips support up to 25 temperature monitoring sources. Up to 6 of those are
50	direct temperature sensor inputs, the others are special sources such as PECI,
51	PCH, and SMBUS. Depending on the chip type, 2 to 6 of the temperature sources
52	can be monitored and compared against minimum, maximum, and critical
53	temperatures. The driver reports up to 10 of the temperatures to the user.
54	There are 4 to 5 fan rotation speed sensors, 8 to 15 analog voltage sensors,
55	one VID, alarms with beep warnings (control unimplemented), and some automatic
56	fan regulation strategies (plus manual fan control mode).
57	
58	The temperature sensor sources on all chips are configurable. The configured
59	source for each of the temperature sensors is provided in tempX_label.
60	
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 to temp6, depending on the chip type.
66	
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. On
69	NCT6775F, fan readings can be divided by a programmable divider (1, 2, 4, 8,
70	16, 32, 64 or 128) to give the readings more range or accuracy; the other chips
71	do not have a fan speed divider. The driver sets the most suitable fan divisor
72	itself; specifically, it increases the divider value each time a fan speed
73	reading returns an invalid value, and it reduces it if the fan speed reading
74	is lower than optimal. Some fans might not be present because they share pins
75	with other functions.
76	
77	Voltage sensors (also known as IN sensors) report their values in millivolts.
78	An alarm is triggered if the voltage has crossed a programmable minimum
79	or maximum limit.
80	
81	The driver supports automatic fan control mode known as Thermal Cruise.
82	In this mode, the chip attempts to keep the measured temperature in a
83	predefined temperature range. If the temperature goes out of range, fan
84	is driven slower/faster to reach the predefined range again.
85	
86	The mode works for fan1-fan5.
87	
88	sysfs attributes
89	----------------
90	
91	pwm[1-5] - this file stores PWM duty cycle or DC value (fan speed) in range:
92		   0 (lowest speed) to 255 (full)
93	
94	pwm[1-5]_enable - this file controls mode of fan/temperature control:
95		* 0 Fan control disabled (fans set to maximum speed)
96		* 1 Manual mode, write to pwm[0-5] any value 0-255
97		* 2 "Thermal Cruise" mode
98		* 3 "Fan Speed Cruise" mode
99		* 4 "Smart Fan III" mode (NCT6775F only)
100		* 5 "Smart Fan IV" mode
101	
102	pwm[1-5]_mode - controls if output is PWM or DC level
103	        * 0 DC output
104	        * 1 PWM output
105	
106	Common fan control attributes
107	-----------------------------
108	
109	pwm[1-5]_temp_sel	Temperature source. Value is temperature sensor index.
110				For example, select '1' for temp1_input.
111	pwm[1-5]_weight_temp_sel
112				Secondary temperature source. Value is temperature
113				sensor index. For example, select '1' for temp1_input.
114				Set to 0 to disable secondary temperature control.
115	
116	If secondary temperature functionality is enabled, it is controlled with the
117	following attributes.
118	
119	pwm[1-5]_weight_duty_step
120				Duty step size.
121	pwm[1-5]_weight_temp_step
122				Temperature step size. With each step over
123				temp_step_base, the value of weight_duty_step is added
124				to the current pwm value.
125	pwm[1-5]_weight_temp_step_base
126				Temperature at which secondary temperature control kicks
127				in.
128	pwm[1-5]_weight_temp_step_tol
129				Temperature step tolerance.
130	
131	Thermal Cruise mode (2)
132	-----------------------
133	
134	If the temperature is in the range defined by:
135	
136	pwm[1-5]_target_temp	Target temperature, unit millidegree Celsius
137				(range 0 - 127000)
138	pwm[1-5]_temp_tolerance
139				Target temperature tolerance, unit millidegree Celsius
140	
141	there are no changes to fan speed. Once the temperature leaves the interval, fan
142	speed increases (if temperature is higher that desired) or decreases (if
143	temperature is lower than desired), using the following limits and time
144	intervals.
145	
146	pwm[1-5]_start		fan pwm start value (range 1 - 255), to start fan
147				when the temperature is above defined range.
148	pwm[1-5]_floor		lowest fan pwm (range 0 - 255) if temperature is below
149				the defined range. If set to 0, the fan is expected to
150				stop if the temperature is below the defined range.
151	pwm[1-5]_step_up_time	milliseconds before fan speed is increased
152	pwm[1-5]_step_down_time	milliseconds before fan speed is decreased
153	pwm[1-5]_stop_time	how many milliseconds must elapse to switch
154				corresponding fan off (when the temperature was below
155				defined range).
156	
157	Speed Cruise mode (3)
158	---------------------
159	
160	This modes tries to keep the fan speed constant.
161	
162	fan[1-5]_target		Target fan speed
163	fan[1-5]_tolerance
164				Target speed tolerance
165	
166	
167	Untested; use at your own risk.
168	
169	Smart Fan IV mode (5)
170	---------------------
171	
172	This mode offers multiple slopes to control the fan speed. The slopes can be
173	controlled by setting the pwm and temperature attributes. When the temperature
174	rises, the chip will calculate the DC/PWM output based on the current slope.
175	There are up to seven data points depending on the chip type. Subsequent data
176	points should be set to higher temperatures and higher pwm values to achieve
177	higher fan speeds with increasing temperature. The last data point reflects
178	critical temperature mode, in which the fans should run at full speed.
179	
180	pwm[1-5]_auto_point[1-7]_pwm
181				pwm value to be set if temperature reaches matching
182				temperature range.
183	pwm[1-5]_auto_point[1-7]_temp
184				Temperature over which the matching pwm is enabled.
185	pwm[1-5]_temp_tolerance
186				Temperature tolerance, unit millidegree Celsius
187	pwm[1-5]_crit_temp_tolerance
188				Temperature tolerance for critical temperature,
189				unit millidegree Celsius
190	
191	pwm[1-5]_step_up_time	milliseconds before fan speed is increased
192	pwm[1-5]_step_down_time	milliseconds before fan speed is decreased
193	
194	Usage Notes
195	-----------
196	
197	On various ASUS boards with NCT6776F, it appears that CPUTIN is not really
198	connected to anything and floats, or that it is connected to some non-standard
199	temperature measurement device. As a result, the temperature reported on CPUTIN
200	will not reflect a usable value. It often reports unreasonably high
201	temperatures, and in some cases the reported temperature declines if the actual
202	temperature increases (similar to the raw PECI temperature value - see PECI
203	specification for details). CPUTIN should therefore be be ignored on ASUS
204	boards. The CPU temperature on ASUS boards is reported from PECI 0.
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