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Based on kernel version 3.2. Page generated on 2012-01-05 23:28 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	  * IT8721F/IT8758E
26	    Prefix: 'it8721'
27	    Addresses scanned: from Super I/O config space (8 I/O ports)
28	    Datasheet: Not publicly available
29	  * SiS950   [clone of IT8705F]
30	    Prefix: 'it87'
31	    Addresses scanned: from Super I/O config space (8 I/O ports)
32	    Datasheet: No longer be available
33	
34	Authors:
35	    Christophe Gauthron
36	    Jean Delvare <khali@linux-fr.org>
37	
38	
39	Module Parameters
40	-----------------
41	
42	* update_vbat: int
43	
44	  0 if vbat should report power on value, 1 if vbat should be updated after
45	  each read. Default is 0. On some boards the battery voltage is provided
46	  by either the battery or the onboard power supply. Only the first reading
47	  at power on will be the actual battery voltage (which the chip does
48	  automatically). On other boards the battery voltage is always fed to
49	  the chip so can be read at any time. Excessive reading may decrease
50	  battery life but no information is given in the datasheet.
51	
52	* fix_pwm_polarity int
53	
54	  Force PWM polarity to active high (DANGEROUS). Some chips are
55	  misconfigured by BIOS - PWM values would be inverted. This option tries
56	  to fix this. Please contact your BIOS manufacturer and ask him for fix.
57	
58	
59	Hardware Interfaces
60	-------------------
61	
62	All the chips suported by this driver are LPC Super-I/O chips, accessed
63	through the LPC bus (ISA-like I/O ports). The IT8712F additionally has an
64	SMBus interface to the hardware monitoring functions. This driver no
65	longer supports this interface though, as it is slower and less reliable
66	than the ISA access, and was only available on a small number of
67	motherboard models.
68	
69	
70	Description
71	-----------
72	
73	This driver implements support for the IT8705F, IT8712F, IT8716F,
74	IT8718F, IT8720F, IT8721F, IT8726F, IT8758E and SiS950 chips.
75	
76	These chips are 'Super I/O chips', supporting floppy disks, infrared ports,
77	joysticks and other miscellaneous stuff. For hardware monitoring, they
78	include an 'environment controller' with 3 temperature sensors, 3 fan
79	rotation speed sensors, 8 voltage sensors, associated alarms, and chassis
80	intrusion detection.
81	
82	The IT8712F and IT8716F additionally feature VID inputs, used to report
83	the Vcore voltage of the processor. The early IT8712F have 5 VID pins,
84	the IT8716F and late IT8712F have 6. They are shared with other functions
85	though, so the functionality may not be available on a given system.
86	
87	The IT8718F and IT8720F also features VID inputs (up to 8 pins) but the value
88	is stored in the Super-I/O configuration space. Due to technical limitations,
89	this value can currently only be read once at initialization time, so
90	the driver won't notice and report changes in the VID value. The two
91	upper VID bits share their pins with voltage inputs (in5 and in6) so you
92	can't have both on a given board.
93	
94	The IT8716F, IT8718F, IT8720F, IT8721F/IT8758E and later IT8712F revisions
95	have support for 2 additional fans. The additional fans are supported by the
96	driver.
97	
98	The IT8716F, IT8718F, IT8720F and IT8721F/IT8758E, and late IT8712F and
99	IT8705F also have optional 16-bit tachometer counters for fans 1 to 3. This
100	is better (no more fan clock divider mess) but not compatible with the older
101	chips and revisions. The 16-bit tachometer mode is enabled by the driver when
102	one of the above chips is detected.
103	
104	The IT8726F is just bit enhanced IT8716F with additional hardware
105	for AMD power sequencing. Therefore the chip will appear as IT8716F
106	to userspace applications.
107	
108	Temperatures are measured in degrees Celsius. An alarm is triggered once
109	when the Overtemperature Shutdown limit is crossed.
110	
111	Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
112	triggered if the rotation speed has dropped below a programmable limit. When
113	16-bit tachometer counters aren't used, fan readings can be divided by
114	a programmable divider (1, 2, 4 or 8) to give the readings more range or
115	accuracy. With a divider of 2, the lowest representable value is around
116	2600 RPM. Not all RPM values can accurately be represented, so some rounding
117	is done.
118	
119	Voltage sensors (also known as IN sensors) report their values in volts. An
120	alarm is triggered if the voltage has crossed a programmable minimum or
121	maximum limit. Note that minimum in this case always means 'closest to
122	zero'; this is important for negative voltage measurements. All voltage
123	inputs can measure voltages between 0 and 4.08 volts, with a resolution of
124	0.016 volt (except IT8721F/IT8758E: 0.012 volt.) The battery voltage in8 does
125	not have limit registers.
126	
127	On the IT8721F/IT8758E, some voltage inputs are internal and scaled inside
128	the chip (in7, in8 and optionally in3). The driver handles this transparently
129	so user-space doesn't have to care.
130	
131	The VID lines (IT8712F/IT8716F/IT8718F/IT8720F) encode the core voltage value:
132	the voltage level your processor should work with. This is hardcoded by
133	the mainboard and/or processor itself. It is a value in volts.
134	
135	If an alarm triggers, it will remain triggered until the hardware register
136	is read at least once. This means that the cause for the alarm may already
137	have disappeared! Note that in the current implementation, all hardware
138	registers are read whenever any data is read (unless it is less than 1.5
139	seconds since the last update). This means that you can easily miss
140	once-only alarms.
141	
142	Out-of-limit readings can also result in beeping, if the chip is properly
143	wired and configured. Beeping can be enabled or disabled per sensor type
144	(temperatures, voltages and fans.)
145	
146	The IT87xx only updates its values each 1.5 seconds; reading it more often
147	will do no harm, but will return 'old' values.
148	
149	To change sensor N to a thermistor, 'echo 4 > tempN_type' where N is 1, 2,
150	or 3. To change sensor N to a thermal diode, 'echo 3 > tempN_type'.
151	Give 0 for unused sensor. Any other value is invalid. To configure this at
152	startup, consult lm_sensors's /etc/sensors.conf. (4 = thermistor;
153	3 = thermal diode)
154	
155	
156	Fan speed control
157	-----------------
158	
159	The fan speed control features are limited to manual PWM mode. Automatic
160	"Smart Guardian" mode control handling is only implemented for older chips
161	(see below.) However if you want to go for "manual mode" just write 1 to
162	pwmN_enable.
163	
164	If you are only able to control the fan speed with very small PWM values,
165	try lowering the PWM base frequency (pwm1_freq). Depending on the fan,
166	it may give you a somewhat greater control range. The same frequency is
167	used to drive all fan outputs, which is why pwm2_freq and pwm3_freq are
168	read-only.
169	
170	
171	Automatic fan speed control (old interface)
172	-------------------------------------------
173	
174	The driver supports the old interface to automatic fan speed control
175	which is implemented by IT8705F chips up to revision F and IT8712F
176	chips up to revision G.
177	
178	This interface implements 4 temperature vs. PWM output trip points.
179	The PWM output of trip point 4 is always the maximum value (fan running
180	at full speed) while the PWM output of the other 3 trip points can be
181	freely chosen. The temperature of all 4 trip points can be freely chosen.
182	Additionally, trip point 1 has an hysteresis temperature attached, to
183	prevent fast switching between fan on and off.
184	
185	The chip automatically computes the PWM output value based on the input
186	temperature, based on this simple rule: if the temperature value is
187	between trip point N and trip point N+1 then the PWM output value is
188	the one of trip point N. The automatic control mode is less flexible
189	than the manual control mode, but it reacts faster, is more robust and
190	doesn't use CPU cycles.
191	
192	Trip points must be set properly before switching to automatic fan speed
193	control mode. The driver will perform basic integrity checks before
194	actually switching to automatic control mode.
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