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Based on kernel version 3.19. Page generated on 2015-02-13 21:21 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	
36	Authors:
37	        Guenter Roeck <linux@roeck-us.net>
38	
39	Description
40	-----------
41	
42	This driver implements support for the Nuvoton NCT6775F, NCT6776F, and NCT6779D
43	and compatible super I/O chips.
44	
45	The chips support up to 25 temperature monitoring sources. Up to 6 of those are
46	direct temperature sensor inputs, the others are special sources such as PECI,
47	PCH, and SMBUS. Depending on the chip type, 2 to 6 of the temperature sources
48	can be monitored and compared against minimum, maximum, and critical
49	temperatures. The driver reports up to 10 of the temperatures to the user.
50	There are 4 to 5 fan rotation speed sensors, 8 to 15 analog voltage sensors,
51	one VID, alarms with beep warnings (control unimplemented), and some automatic
52	fan regulation strategies (plus manual fan control mode).
53	
54	The temperature sensor sources on all chips are configurable. The configured
55	source for each of the temperature sensors is provided in tempX_label.
56	
57	Temperatures are measured in degrees Celsius and measurement resolution is
58	either 1 degC or 0.5 degC, depending on the temperature source and
59	configuration. An alarm is triggered when the temperature gets higher than
60	the high limit; it stays on until the temperature falls below the hysteresis
61	value. Alarms are only supported for temp1 to temp6, depending on the chip type.
62	
63	Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
64	triggered if the rotation speed has dropped below a programmable limit. On
65	NCT6775F, fan readings can be divided by a programmable divider (1, 2, 4, 8,
66	16, 32, 64 or 128) to give the readings more range or accuracy; the other chips
67	do not have a fan speed divider. The driver sets the most suitable fan divisor
68	itself; specifically, it increases the divider value each time a fan speed
69	reading returns an invalid value, and it reduces it if the fan speed reading
70	is lower than optimal. Some fans might not be present because they share pins
71	with other functions.
72	
73	Voltage sensors (also known as IN sensors) report their values in millivolts.
74	An alarm is triggered if the voltage has crossed a programmable minimum
75	or maximum limit.
76	
77	The driver supports automatic fan control mode known as Thermal Cruise.
78	In this mode, the chip attempts to keep the measured temperature in a
79	predefined temperature range. If the temperature goes out of range, fan
80	is driven slower/faster to reach the predefined range again.
81	
82	The mode works for fan1-fan5.
83	
84	sysfs attributes
85	----------------
86	
87	pwm[1-5] - this file stores PWM duty cycle or DC value (fan speed) in range:
88		   0 (lowest speed) to 255 (full)
89	
90	pwm[1-5]_enable - this file controls mode of fan/temperature control:
91		* 0 Fan control disabled (fans set to maximum speed)
92		* 1 Manual mode, write to pwm[0-5] any value 0-255
93		* 2 "Thermal Cruise" mode
94		* 3 "Fan Speed Cruise" mode
95		* 4 "Smart Fan III" mode (NCT6775F only)
96		* 5 "Smart Fan IV" mode
97	
98	pwm[1-5]_mode - controls if output is PWM or DC level
99	        * 0 DC output
100	        * 1 PWM output
101	
102	Common fan control attributes
103	-----------------------------
104	
105	pwm[1-5]_temp_sel	Temperature source. Value is temperature sensor index.
106				For example, select '1' for temp1_input.
107	pwm[1-5]_weight_temp_sel
108				Secondary temperature source. Value is temperature
109				sensor index. For example, select '1' for temp1_input.
110				Set to 0 to disable secondary temperature control.
111	
112	If secondary temperature functionality is enabled, it is controlled with the
113	following attributes.
114	
115	pwm[1-5]_weight_duty_step
116				Duty step size.
117	pwm[1-5]_weight_temp_step
118				Temperature step size. With each step over
119				temp_step_base, the value of weight_duty_step is added
120				to the current pwm value.
121	pwm[1-5]_weight_temp_step_base
122				Temperature at which secondary temperature control kicks
123				in.
124	pwm[1-5]_weight_temp_step_tol
125				Temperature step tolerance.
126	
127	Thermal Cruise mode (2)
128	-----------------------
129	
130	If the temperature is in the range defined by:
131	
132	pwm[1-5]_target_temp	Target temperature, unit millidegree Celsius
133				(range 0 - 127000)
134	pwm[1-5]_temp_tolerance
135				Target temperature tolerance, unit millidegree Celsius
136	
137	there are no changes to fan speed. Once the temperature leaves the interval, fan
138	speed increases (if temperature is higher that desired) or decreases (if
139	temperature is lower than desired), using the following limits and time
140	intervals.
141	
142	pwm[1-5]_start		fan pwm start value (range 1 - 255), to start fan
143				when the temperature is above defined range.
144	pwm[1-5]_floor		lowest fan pwm (range 0 - 255) if temperature is below
145				the defined range. If set to 0, the fan is expected to
146				stop if the temperature is below the defined range.
147	pwm[1-5]_step_up_time	milliseconds before fan speed is increased
148	pwm[1-5]_step_down_time	milliseconds before fan speed is decreased
149	pwm[1-5]_stop_time	how many milliseconds must elapse to switch
150				corresponding fan off (when the temperature was below
151				defined range).
152	
153	Speed Cruise mode (3)
154	---------------------
155	
156	This modes tries to keep the fan speed constant.
157	
158	fan[1-5]_target		Target fan speed
159	fan[1-5]_tolerance
160				Target speed tolerance
161	
162	
163	Untested; use at your own risk.
164	
165	Smart Fan IV mode (5)
166	---------------------
167	
168	This mode offers multiple slopes to control the fan speed. The slopes can be
169	controlled by setting the pwm and temperature attributes. When the temperature
170	rises, the chip will calculate the DC/PWM output based on the current slope.
171	There are up to seven data points depending on the chip type. Subsequent data
172	points should be set to higher temperatures and higher pwm values to achieve
173	higher fan speeds with increasing temperature. The last data point reflects
174	critical temperature mode, in which the fans should run at full speed.
175	
176	pwm[1-5]_auto_point[1-7]_pwm
177				pwm value to be set if temperature reaches matching
178				temperature range.
179	pwm[1-5]_auto_point[1-7]_temp
180				Temperature over which the matching pwm is enabled.
181	pwm[1-5]_temp_tolerance
182				Temperature tolerance, unit millidegree Celsius
183	pwm[1-5]_crit_temp_tolerance
184				Temperature tolerance for critical temperature,
185				unit millidegree Celsius
186	
187	pwm[1-5]_step_up_time	milliseconds before fan speed is increased
188	pwm[1-5]_step_down_time	milliseconds before fan speed is decreased
189	
190	Usage Notes
191	-----------
192	
193	On various ASUS boards with NCT6776F, it appears that CPUTIN is not really
194	connected to anything and floats, or that it is connected to some non-standard
195	temperature measurement device. As a result, the temperature reported on CPUTIN
196	will not reflect a usable value. It often reports unreasonably high
197	temperatures, and in some cases the reported temperature declines if the actual
198	temperature increases (similar to the raw PECI temperature value - see PECI
199	specification for details). CPUTIN should therefore be be ignored on ASUS
200	boards. The CPU temperature on ASUS boards is reported from PECI 0.
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