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Based on kernel version 2.6.34. Page generated on 2010-05-31 16:02 EST.

1	Kernel driver it87
2	==================
3	
4	Supported chips:
5	  * IT8705F
6	    Prefix: 'it87'
7	    Addresses scanned: from Super I/O config space (8 I/O ports)
8	    Datasheet: Once publicly available at the ITE website, but no longer
9	  * IT8712F
10	    Prefix: 'it8712'
11	    Addresses scanned: from Super I/O config space (8 I/O ports)
12	    Datasheet: Once publicly available at the ITE website, but no longer
13	  * IT8716F/IT8726F
14	    Prefix: 'it8716'
15	    Addresses scanned: from Super I/O config space (8 I/O ports)
16	    Datasheet: Once publicly available at the ITE website, but no longer
17	  * IT8718F
18	    Prefix: 'it8718'
19	    Addresses scanned: from Super I/O config space (8 I/O ports)
20	    Datasheet: Once publicly available at the ITE website, but no longer
21	  * IT8720F
22	    Prefix: 'it8720'
23	    Addresses scanned: from Super I/O config space (8 I/O ports)
24	    Datasheet: Not publicly available
25	  * SiS950   [clone of IT8705F]
26	    Prefix: 'it87'
27	    Addresses scanned: from Super I/O config space (8 I/O ports)
28	    Datasheet: No longer be available
29	
30	Authors:
31	    Christophe Gauthron
32	    Jean Delvare <khali[AT]linux-fr[DOT]org>
33	
34	
35	Module Parameters
36	-----------------
37	
38	* update_vbat: int
39	
40	  0 if vbat should report power on value, 1 if vbat should be updated after
41	  each read. Default is 0. On some boards the battery voltage is provided
42	  by either the battery or the onboard power supply. Only the first reading
43	  at power on will be the actual battery voltage (which the chip does
44	  automatically). On other boards the battery voltage is always fed to
45	  the chip so can be read at any time. Excessive reading may decrease
46	  battery life but no information is given in the datasheet.
47	
48	* fix_pwm_polarity int
49	
50	  Force PWM polarity to active high (DANGEROUS). Some chips are
51	  misconfigured by BIOS - PWM values would be inverted. This option tries
52	  to fix this. Please contact your BIOS manufacturer and ask him for fix.
53	
54	
55	Hardware Interfaces
56	-------------------
57	
58	All the chips suported by this driver are LPC Super-I/O chips, accessed
59	through the LPC bus (ISA-like I/O ports). The IT8712F additionally has an
60	SMBus interface to the hardware monitoring functions. This driver no
61	longer supports this interface though, as it is slower and less reliable
62	than the ISA access, and was only available on a small number of
63	motherboard models.
64	
65	
66	Description
67	-----------
68	
69	This driver implements support for the IT8705F, IT8712F, IT8716F,
70	IT8718F, IT8720F, IT8726F and SiS950 chips.
71	
72	These chips are 'Super I/O chips', supporting floppy disks, infrared ports,
73	joysticks and other miscellaneous stuff. For hardware monitoring, they
74	include an 'environment controller' with 3 temperature sensors, 3 fan
75	rotation speed sensors, 8 voltage sensors, and associated alarms.
76	
77	The IT8712F and IT8716F additionally feature VID inputs, used to report
78	the Vcore voltage of the processor. The early IT8712F have 5 VID pins,
79	the IT8716F and late IT8712F have 6. They are shared with other functions
80	though, so the functionality may not be available on a given system.
81	
82	The IT8718F and IT8720F also features VID inputs (up to 8 pins) but the value
83	is stored in the Super-I/O configuration space. Due to technical limitations,
84	this value can currently only be read once at initialization time, so
85	the driver won't notice and report changes in the VID value. The two
86	upper VID bits share their pins with voltage inputs (in5 and in6) so you
87	can't have both on a given board.
88	
89	The IT8716F, IT8718F, IT8720F and later IT8712F revisions have support for
90	2 additional fans. The additional fans are supported by the driver.
91	
92	The IT8716F, IT8718F and IT8720F, and late IT8712F and IT8705F also have
93	optional 16-bit tachometer counters for fans 1 to 3. This is better (no more
94	fan clock divider mess) but not compatible with the older chips and
95	revisions. The 16-bit tachometer mode is enabled by the driver when one
96	of the above chips is detected.
97	
98	The IT8726F is just bit enhanced IT8716F with additional hardware
99	for AMD power sequencing. Therefore the chip will appear as IT8716F
100	to userspace applications.
101	
102	Temperatures are measured in degrees Celsius. An alarm is triggered once
103	when the Overtemperature Shutdown limit is crossed.
104	
105	Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
106	triggered if the rotation speed has dropped below a programmable limit. When
107	16-bit tachometer counters aren't used, fan readings can be divided by
108	a programmable divider (1, 2, 4 or 8) to give the readings more range or
109	accuracy. With a divider of 2, the lowest representable value is around
110	2600 RPM. Not all RPM values can accurately be represented, so some rounding
111	is done.
112	
113	Voltage sensors (also known as IN sensors) report their values in volts. An
114	alarm is triggered if the voltage has crossed a programmable minimum or
115	maximum limit. Note that minimum in this case always means 'closest to
116	zero'; this is important for negative voltage measurements. All voltage
117	inputs can measure voltages between 0 and 4.08 volts, with a resolution of
118	0.016 volt. The battery voltage in8 does not have limit registers.
119	
120	The VID lines (IT8712F/IT8716F/IT8718F/IT8720F) encode the core voltage value:
121	the voltage level your processor should work with. This is hardcoded by
122	the mainboard and/or processor itself. It is a value in volts.
123	
124	If an alarm triggers, it will remain triggered until the hardware register
125	is read at least once. This means that the cause for the alarm may already
126	have disappeared! Note that in the current implementation, all hardware
127	registers are read whenever any data is read (unless it is less than 1.5
128	seconds since the last update). This means that you can easily miss
129	once-only alarms.
130	
131	Out-of-limit readings can also result in beeping, if the chip is properly
132	wired and configured. Beeping can be enabled or disabled per sensor type
133	(temperatures, voltages and fans.)
134	
135	The IT87xx only updates its values each 1.5 seconds; reading it more often
136	will do no harm, but will return 'old' values.
137	
138	To change sensor N to a thermistor, 'echo 4 > tempN_type' where N is 1, 2,
139	or 3. To change sensor N to a thermal diode, 'echo 3 > tempN_type'.
140	Give 0 for unused sensor. Any other value is invalid. To configure this at
141	startup, consult lm_sensors's /etc/sensors.conf. (4 = thermistor;
142	3 = thermal diode)
143	
144	
145	Fan speed control
146	-----------------
147	
148	The fan speed control features are limited to manual PWM mode. Automatic
149	"Smart Guardian" mode control handling is only implemented for older chips
150	(see below.) However if you want to go for "manual mode" just write 1 to
151	pwmN_enable.
152	
153	If you are only able to control the fan speed with very small PWM values,
154	try lowering the PWM base frequency (pwm1_freq). Depending on the fan,
155	it may give you a somewhat greater control range. The same frequency is
156	used to drive all fan outputs, which is why pwm2_freq and pwm3_freq are
157	read-only.
158	
159	
160	Automatic fan speed control (old interface)
161	-------------------------------------------
162	
163	The driver supports the old interface to automatic fan speed control
164	which is implemented by IT8705F chips up to revision F and IT8712F
165	chips up to revision G.
166	
167	This interface implements 4 temperature vs. PWM output trip points.
168	The PWM output of trip point 4 is always the maximum value (fan running
169	at full speed) while the PWM output of the other 3 trip points can be
170	freely chosen. The temperature of all 4 trip points can be freely chosen.
171	Additionally, trip point 1 has an hysteresis temperature attached, to
172	prevent fast switching between fan on and off.
173	
174	The chip automatically computes the PWM output value based on the input
175	temperature, based on this simple rule: if the temperature value is
176	between trip point N and trip point N+1 then the PWM output value is
177	the one of trip point N. The automatic control mode is less flexible
178	than the manual control mode, but it reacts faster, is more robust and
179	doesn't use CPU cycles.
180	
181	Trip points must be set properly before switching to automatic fan speed
182	control mode. The driver will perform basic integrity checks before
183	actually switching to automatic control mode.
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