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Based on kernel version 3.15.4. Page generated on 2014-07-07 09:03 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 NCT5572D/NCT6771F/NCT6772F/NCT6775F/W83677HG-I
12	    Prefix: 'nct6775'
13	    Addresses scanned: ISA address retrieved from Super I/O registers
14	    Datasheet: Available from Nuvoton upon request
15	  * Nuvoton NCT5577D/NCT6776D/NCT6776F
16	    Prefix: 'nct6776'
17	    Addresses scanned: ISA address retrieved from Super I/O registers
18	    Datasheet: Available from Nuvoton upon request
19	  * Nuvoton NCT5532D/NCT6779D
20	    Prefix: 'nct6779'
21	    Addresses scanned: ISA address retrieved from Super I/O registers
22	    Datasheet: Available from Nuvoton upon request
23	
24	Authors:
25	        Guenter Roeck <linux@roeck-us.net>
26	
27	Description
28	-----------
29	
30	This driver implements support for the Nuvoton NCT6775F, NCT6776F, and NCT6779D
31	and compatible super I/O chips.
32	
33	The chips support up to 25 temperature monitoring sources. Up to 6 of those are
34	direct temperature sensor inputs, the others are special sources such as PECI,
35	PCH, and SMBUS. Depending on the chip type, 2 to 6 of the temperature sources
36	can be monitored and compared against minimum, maximum, and critical
37	temperatures. The driver reports up to 10 of the temperatures to the user.
38	There are 4 to 5 fan rotation speed sensors, 8 to 15 analog voltage sensors,
39	one VID, alarms with beep warnings (control unimplemented), and some automatic
40	fan regulation strategies (plus manual fan control mode).
41	
42	The temperature sensor sources on all chips are configurable. The configured
43	source for each of the temperature sensors is provided in tempX_label.
44	
45	Temperatures are measured in degrees Celsius and measurement resolution is
46	either 1 degC or 0.5 degC, depending on the temperature source and
47	configuration. An alarm is triggered when the temperature gets higher than
48	the high limit; it stays on until the temperature falls below the hysteresis
49	value. Alarms are only supported for temp1 to temp6, depending on the chip type.
50	
51	Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
52	triggered if the rotation speed has dropped below a programmable limit. On
53	NCT6775F, fan readings can be divided by a programmable divider (1, 2, 4, 8,
54	16, 32, 64 or 128) to give the readings more range or accuracy; the other chips
55	do not have a fan speed divider. The driver sets the most suitable fan divisor
56	itself; specifically, it increases the divider value each time a fan speed
57	reading returns an invalid value, and it reduces it if the fan speed reading
58	is lower than optimal. Some fans might not be present because they share pins
59	with other functions.
60	
61	Voltage sensors (also known as IN sensors) report their values in millivolts.
62	An alarm is triggered if the voltage has crossed a programmable minimum
63	or maximum limit.
64	
65	The driver supports automatic fan control mode known as Thermal Cruise.
66	In this mode, the chip attempts to keep the measured temperature in a
67	predefined temperature range. If the temperature goes out of range, fan
68	is driven slower/faster to reach the predefined range again.
69	
70	The mode works for fan1-fan5.
71	
72	sysfs attributes
73	----------------
74	
75	pwm[1-5] - this file stores PWM duty cycle or DC value (fan speed) in range:
76		   0 (lowest speed) to 255 (full)
77	
78	pwm[1-5]_enable - this file controls mode of fan/temperature control:
79		* 0 Fan control disabled (fans set to maximum speed)
80		* 1 Manual mode, write to pwm[0-5] any value 0-255
81		* 2 "Thermal Cruise" mode
82		* 3 "Fan Speed Cruise" mode
83		* 4 "Smart Fan III" mode (NCT6775F only)
84		* 5 "Smart Fan IV" mode
85	
86	pwm[1-5]_mode - controls if output is PWM or DC level
87	        * 0 DC output
88	        * 1 PWM output
89	
90	Common fan control attributes
91	-----------------------------
92	
93	pwm[1-5]_temp_sel	Temperature source. Value is temperature sensor index.
94				For example, select '1' for temp1_input.
95	pwm[1-5]_weight_temp_sel
96				Secondary temperature source. Value is temperature
97				sensor index. For example, select '1' for temp1_input.
98				Set to 0 to disable secondary temperature control.
99	
100	If secondary temperature functionality is enabled, it is controlled with the
101	following attributes.
102	
103	pwm[1-5]_weight_duty_step
104				Duty step size.
105	pwm[1-5]_weight_temp_step
106				Temperature step size. With each step over
107				temp_step_base, the value of weight_duty_step is added
108				to the current pwm value.
109	pwm[1-5]_weight_temp_step_base
110				Temperature at which secondary temperature control kicks
111				in.
112	pwm[1-5]_weight_temp_step_tol
113				Temperature step tolerance.
114	
115	Thermal Cruise mode (2)
116	-----------------------
117	
118	If the temperature is in the range defined by:
119	
120	pwm[1-5]_target_temp	Target temperature, unit millidegree Celsius
121				(range 0 - 127000)
122	pwm[1-5]_temp_tolerance
123				Target temperature tolerance, unit millidegree Celsius
124	
125	there are no changes to fan speed. Once the temperature leaves the interval, fan
126	speed increases (if temperature is higher that desired) or decreases (if
127	temperature is lower than desired), using the following limits and time
128	intervals.
129	
130	pwm[1-5]_start		fan pwm start value (range 1 - 255), to start fan
131				when the temperature is above defined range.
132	pwm[1-5]_floor		lowest fan pwm (range 0 - 255) if temperature is below
133				the defined range. If set to 0, the fan is expected to
134				stop if the temperature is below the defined range.
135	pwm[1-5]_step_up_time	milliseconds before fan speed is increased
136	pwm[1-5]_step_down_time	milliseconds before fan speed is decreased
137	pwm[1-5]_stop_time	how many milliseconds must elapse to switch
138				corresponding fan off (when the temperature was below
139				defined range).
140	
141	Speed Cruise mode (3)
142	---------------------
143	
144	This modes tries to keep the fan speed constant.
145	
146	fan[1-5]_target		Target fan speed
147	fan[1-5]_tolerance
148				Target speed tolerance
149	
150	
151	Untested; use at your own risk.
152	
153	Smart Fan IV mode (5)
154	---------------------
155	
156	This mode offers multiple slopes to control the fan speed. The slopes can be
157	controlled by setting the pwm and temperature attributes. When the temperature
158	rises, the chip will calculate the DC/PWM output based on the current slope.
159	There are up to seven data points depending on the chip type. Subsequent data
160	points should be set to higher temperatures and higher pwm values to achieve
161	higher fan speeds with increasing temperature. The last data point reflects
162	critical temperature mode, in which the fans should run at full speed.
163	
164	pwm[1-5]_auto_point[1-7]_pwm
165				pwm value to be set if temperature reaches matching
166				temperature range.
167	pwm[1-5]_auto_point[1-7]_temp
168				Temperature over which the matching pwm is enabled.
169	pwm[1-5]_temp_tolerance
170				Temperature tolerance, unit millidegree Celsius
171	pwm[1-5]_crit_temp_tolerance
172				Temperature tolerance for critical temperature,
173				unit millidegree Celsius
174	
175	pwm[1-5]_step_up_time	milliseconds before fan speed is increased
176	pwm[1-5]_step_down_time	milliseconds before fan speed is decreased
177	
178	Usage Notes
179	-----------
180	
181	On various ASUS boards with NCT6776F, it appears that CPUTIN is not really
182	connected to anything and floats, or that it is connected to some non-standard
183	temperature measurement device. As a result, the temperature reported on CPUTIN
184	will not reflect a usable value. It often reports unreasonably high
185	temperatures, and in some cases the reported temperature declines if the actual
186	temperature increases (similar to the raw PECI temperature value - see PECI
187	specification for details). CPUTIN should therefore be be ignored on ASUS
188	boards. The CPU temperature on ASUS boards is reported from PECI 0.
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