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Documentation / hwmon / it87

Based on kernel version 2.6.26. Page generated on 2008-07-16 21:12 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: Publicly available at the ITE website
9	               http://www.ite.com.tw/
10	  * IT8712F
11	    Prefix: 'it8712'
12	    Addresses scanned: from Super I/O config space (8 I/O ports)
13	    Datasheet: Publicly available at the ITE website
14	               http://www.ite.com.tw/
15	  * IT8716F/IT8726F
16	    Prefix: 'it8716'
17	    Addresses scanned: from Super I/O config space (8 I/O ports)
18	    Datasheet: Publicly available at the ITE website
19	               http://www.ite.com.tw/product_info/file/pc/IT8716F_V0.3.ZIP
20	               http://www.ite.com.tw/product_info/file/pc/IT8726F_V0.3.pdf
21	  * IT8718F
22	    Prefix: 'it8718'
23	    Addresses scanned: from Super I/O config space (8 I/O ports)
24	    Datasheet: Publicly available at the ITE website
25	               http://www.ite.com.tw/product_info/file/pc/IT8718F_V0.2.zip
26	               http://www.ite.com.tw/product_info/file/pc/IT8718F_V0%203_(for%20C%20version).zip
27	  * SiS950   [clone of IT8705F]
28	    Prefix: 'it87'
29	    Addresses scanned: from Super I/O config space (8 I/O ports)
30	    Datasheet: No longer be available
31	
32	Authors:
33	    Christophe Gauthron
34	    Jean Delvare <khali[AT]linux-fr[DOT]org>
35	
36	
37	Module Parameters
38	-----------------
39	
40	* update_vbat: int
41	
42	  0 if vbat should report power on value, 1 if vbat should be updated after
43	  each read. Default is 0. On some boards the battery voltage is provided
44	  by either the battery or the onboard power supply. Only the first reading
45	  at power on will be the actual battery voltage (which the chip does
46	  automatically). On other boards the battery voltage is always fed to
47	  the chip so can be read at any time. Excessive reading may decrease
48	  battery life but no information is given in the datasheet.
49	
50	* fix_pwm_polarity int
51	
52	  Force PWM polarity to active high (DANGEROUS). Some chips are
53	  misconfigured by BIOS - PWM values would be inverted. This option tries
54	  to fix this. Please contact your BIOS manufacturer and ask him for fix.
55	
56	
57	Hardware Interfaces
58	-------------------
59	
60	All the chips suported by this driver are LPC Super-I/O chips, accessed
61	through the LPC bus (ISA-like I/O ports). The IT8712F additionally has an
62	SMBus interface to the hardware monitoring functions. This driver no
63	longer supports this interface though, as it is slower and less reliable
64	than the ISA access, and was only available on a small number of
65	motherboard models.
66	
67	
68	Description
69	-----------
70	
71	This driver implements support for the IT8705F, IT8712F, IT8716F,
72	IT8718F, IT8726F and SiS950 chips.
73	
74	These chips are 'Super I/O chips', supporting floppy disks, infrared ports,
75	joysticks and other miscellaneous stuff. For hardware monitoring, they
76	include an 'environment controller' with 3 temperature sensors, 3 fan
77	rotation speed sensors, 8 voltage sensors, and associated alarms.
78	
79	The IT8712F and IT8716F additionally feature VID inputs, used to report
80	the Vcore voltage of the processor. The early IT8712F have 5 VID pins,
81	the IT8716F and late IT8712F have 6. They are shared with other functions
82	though, so the functionality may not be available on a given system.
83	The driver dumbly assume it is there.
84	
85	The IT8718F also features VID inputs (up to 8 pins) but the value is
86	stored in the Super-I/O configuration space. Due to technical limitations,
87	this value can currently only be read once at initialization time, so
88	the driver won't notice and report changes in the VID value. The two
89	upper VID bits share their pins with voltage inputs (in5 and in6) so you
90	can't have both on a given board.
91	
92	The IT8716F, IT8718F and later IT8712F revisions have support for
93	2 additional fans. They are supported by the driver for the IT8716F and
94	IT8718F but not for the IT8712F
95	
96	The IT8716F and IT8718F, and late IT8712F and IT8705F also have optional
97	16-bit tachometer counters for fans 1 to 3. This is better (no more fan
98	clock divider mess) but not compatible with the older chips and
99	revisions. For now, the driver only uses the 16-bit mode on the
100	IT8716F and IT8718F.
101	
102	The IT8726F is just bit enhanced IT8716F with additional hardware
103	for AMD power sequencing. Therefore the chip will appear as IT8716F
104	to userspace applications.
105	
106	Temperatures are measured in degrees Celsius. An alarm is triggered once
107	when the Overtemperature Shutdown limit is crossed.
108	
109	Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
110	triggered if the rotation speed has dropped below a programmable limit. When
111	16-bit tachometer counters aren't used, fan readings can be divided by
112	a programmable divider (1, 2, 4 or 8) to give the readings more range or
113	accuracy. With a divider of 2, the lowest representable value is around
114	2600 RPM. Not all RPM values can accurately be represented, so some rounding
115	is done.
116	
117	Voltage sensors (also known as IN sensors) report their values in volts. An
118	alarm is triggered if the voltage has crossed a programmable minimum or
119	maximum limit. Note that minimum in this case always means 'closest to
120	zero'; this is important for negative voltage measurements. All voltage
121	inputs can measure voltages between 0 and 4.08 volts, with a resolution of
122	0.016 volt. The battery voltage in8 does not have limit registers.
123	
124	The VID lines (IT8712F/IT8716F/IT8718F) encode the core voltage value:
125	the voltage level your processor should work with. This is hardcoded by
126	the mainboard and/or processor itself. It is a value in volts.
127	
128	If an alarm triggers, it will remain triggered until the hardware register
129	is read at least once. This means that the cause for the alarm may already
130	have disappeared! Note that in the current implementation, all hardware
131	registers are read whenever any data is read (unless it is less than 1.5
132	seconds since the last update). This means that you can easily miss
133	once-only alarms.
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 2 > 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. (2 = 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 not implemented. However
150	if you want to go for "manual mode" just write 1 to pwmN_enable.
151	
152	If you are only able to control the fan speed with very small PWM values,
153	try lowering the PWM base frequency (pwm1_freq). Depending on the fan,
154	it may give you a somewhat greater control range. The same frequency is
155	used to drive all fan outputs, which is why pwm2_freq and pwm3_freq are
156	read-only.
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