About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Documentation / hwmon / it87




Custom Search

Based on kernel version 4.1. Page generated on 2015-06-28 12:12 EST.

1	Kernel driver it87
2	==================
3	
4	Supported chips:
5	  * IT8603E/IT8623E
6	    Prefix: 'it8603'
7	    Addresses scanned: from Super I/O config space (8 I/O ports)
8	    Datasheet: Not publicly available
9	  * IT8620E
10	    Prefix: 'it8620'
11	    Addresses scanned: from Super I/O config space (8 I/O ports)
12	    Datasheet: Not publicly available
13	  * IT8705F
14	    Prefix: 'it87'
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	  * IT8712F
18	    Prefix: 'it8712'
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	  * IT8716F/IT8726F
22	    Prefix: 'it8716'
23	    Addresses scanned: from Super I/O config space (8 I/O ports)
24	    Datasheet: Once publicly available at the ITE website, but no longer
25	  * IT8718F
26	    Prefix: 'it8718'
27	    Addresses scanned: from Super I/O config space (8 I/O ports)
28	    Datasheet: Once publicly available at the ITE website, but no longer
29	  * IT8720F
30	    Prefix: 'it8720'
31	    Addresses scanned: from Super I/O config space (8 I/O ports)
32	    Datasheet: Not publicly available
33	  * IT8721F/IT8758E
34	    Prefix: 'it8721'
35	    Addresses scanned: from Super I/O config space (8 I/O ports)
36	    Datasheet: Not publicly available
37	  * IT8728F
38	    Prefix: 'it8728'
39	    Addresses scanned: from Super I/O config space (8 I/O ports)
40	    Datasheet: Not publicly available
41	  * IT8771E
42	    Prefix: 'it8771'
43	    Addresses scanned: from Super I/O config space (8 I/O ports)
44	    Datasheet: Not publicly available
45	  * IT8772E
46	    Prefix: 'it8772'
47	    Addresses scanned: from Super I/O config space (8 I/O ports)
48	    Datasheet: Not publicly available
49	  * IT8781F
50	    Prefix: 'it8781'
51	    Addresses scanned: from Super I/O config space (8 I/O ports)
52	    Datasheet: Not publicly available
53	  * IT8782F
54	    Prefix: 'it8782'
55	    Addresses scanned: from Super I/O config space (8 I/O ports)
56	    Datasheet: Not publicly available
57	  * IT8783E/F
58	    Prefix: 'it8783'
59	    Addresses scanned: from Super I/O config space (8 I/O ports)
60	    Datasheet: Not publicly available
61	  * IT8786E
62	    Prefix: 'it8786'
63	    Addresses scanned: from Super I/O config space (8 I/O ports)
64	    Datasheet: Not publicly available
65	  * IT8790E
66	    Prefix: 'it8790'
67	    Addresses scanned: from Super I/O config space (8 I/O ports)
68	    Datasheet: Not publicly available
69	  * SiS950   [clone of IT8705F]
70	    Prefix: 'it87'
71	    Addresses scanned: from Super I/O config space (8 I/O ports)
72	    Datasheet: No longer be available
73	
74	Authors:
75	    Christophe Gauthron
76	    Jean Delvare <jdelvare@suse.de>
77	
78	
79	Module Parameters
80	-----------------
81	
82	* update_vbat: int
83	
84	  0 if vbat should report power on value, 1 if vbat should be updated after
85	  each read. Default is 0. On some boards the battery voltage is provided
86	  by either the battery or the onboard power supply. Only the first reading
87	  at power on will be the actual battery voltage (which the chip does
88	  automatically). On other boards the battery voltage is always fed to
89	  the chip so can be read at any time. Excessive reading may decrease
90	  battery life but no information is given in the datasheet.
91	
92	* fix_pwm_polarity int
93	
94	  Force PWM polarity to active high (DANGEROUS). Some chips are
95	  misconfigured by BIOS - PWM values would be inverted. This option tries
96	  to fix this. Please contact your BIOS manufacturer and ask him for fix.
97	
98	
99	Hardware Interfaces
100	-------------------
101	
102	All the chips supported by this driver are LPC Super-I/O chips, accessed
103	through the LPC bus (ISA-like I/O ports). The IT8712F additionally has an
104	SMBus interface to the hardware monitoring functions. This driver no
105	longer supports this interface though, as it is slower and less reliable
106	than the ISA access, and was only available on a small number of
107	motherboard models.
108	
109	
110	Description
111	-----------
112	
113	This driver implements support for the IT8603E, IT8620E, IT8623E, IT8705F,
114	IT8712F, IT8716F, IT8718F, IT8720F, IT8721F, IT8726F, IT8728F, IT8758E,
115	IT8771E, IT8772E, IT8781F, IT8782F, IT8783E/F, IT8786E, IT8790E, and SiS950
116	chips.
117	
118	These chips are 'Super I/O chips', supporting floppy disks, infrared ports,
119	joysticks and other miscellaneous stuff. For hardware monitoring, they
120	include an 'environment controller' with 3 temperature sensors, 3 fan
121	rotation speed sensors, 8 voltage sensors, associated alarms, and chassis
122	intrusion detection.
123	
124	The IT8712F and IT8716F additionally feature VID inputs, used to report
125	the Vcore voltage of the processor. The early IT8712F have 5 VID pins,
126	the IT8716F and late IT8712F have 6. They are shared with other functions
127	though, so the functionality may not be available on a given system.
128	
129	The IT8718F and IT8720F also features VID inputs (up to 8 pins) but the value
130	is stored in the Super-I/O configuration space. Due to technical limitations,
131	this value can currently only be read once at initialization time, so
132	the driver won't notice and report changes in the VID value. The two
133	upper VID bits share their pins with voltage inputs (in5 and in6) so you
134	can't have both on a given board.
135	
136	The IT8716F, IT8718F, IT8720F, IT8721F/IT8758E and later IT8712F revisions
137	have support for 2 additional fans. The additional fans are supported by the
138	driver.
139	
140	The IT8716F, IT8718F, IT8720F, IT8721F/IT8758E, IT8781F, IT8782F, IT8783E/F,
141	and late IT8712F and IT8705F also have optional 16-bit tachometer counters
142	for fans 1 to 3. This is better (no more fan clock divider mess) but not
143	compatible with the older chips and revisions. The 16-bit tachometer mode
144	is enabled by the driver when one of the above chips is detected.
145	
146	The IT8726F is just bit enhanced IT8716F with additional hardware
147	for AMD power sequencing. Therefore the chip will appear as IT8716F
148	to userspace applications.
149	
150	The IT8728F, IT8771E, and IT8772E are considered compatible with the IT8721F,
151	until a datasheet becomes available (hopefully.)
152	
153	The IT8603E/IT8623E is a custom design, hardware monitoring part is similar to
154	IT8728F. It only supports 3 fans, 16-bit fan mode, and the full speed mode
155	of the fan is not supported (value 0 of pwmX_enable).
156	
157	The IT8620E is another custom design, hardware monitoring part is similar to
158	IT8728F. It only supports 16-bit fan mode.
159	
160	The IT8790E supports up to 3 fans. 16-bit fan mode is always enabled.
161	
162	Temperatures are measured in degrees Celsius. An alarm is triggered once
163	when the Overtemperature Shutdown limit is crossed.
164	
165	Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
166	triggered if the rotation speed has dropped below a programmable limit. When
167	16-bit tachometer counters aren't used, fan readings can be divided by
168	a programmable divider (1, 2, 4 or 8) to give the readings more range or
169	accuracy. With a divider of 2, the lowest representable value is around
170	2600 RPM. Not all RPM values can accurately be represented, so some rounding
171	is done.
172	
173	Voltage sensors (also known as IN sensors) report their values in volts. An
174	alarm is triggered if the voltage has crossed a programmable minimum or
175	maximum limit. Note that minimum in this case always means 'closest to
176	zero'; this is important for negative voltage measurements. All voltage
177	inputs can measure voltages between 0 and 4.08 volts, with a resolution of
178	0.016 volt (except IT8603E, IT8721F/IT8758E and IT8728F: 0.012 volt.) The
179	battery voltage in8 does not have limit registers.
180	
181	On the IT8603E, IT8721F/IT8758E, IT8781F, IT8782F, and IT8783E/F, some
182	voltage inputs are internal and scaled inside the chip:
183	* in3 (optional)
184	* in7 (optional for IT8781F, IT8782F, and IT8783E/F)
185	* in8 (always)
186	* in9 (relevant for IT8603E only)
187	The driver handles this transparently so user-space doesn't have to care.
188	
189	The VID lines (IT8712F/IT8716F/IT8718F/IT8720F) encode the core voltage value:
190	the voltage level your processor should work with. This is hardcoded by
191	the mainboard and/or processor itself. It is a value in volts.
192	
193	If an alarm triggers, it will remain triggered until the hardware register
194	is read at least once. This means that the cause for the alarm may already
195	have disappeared! Note that in the current implementation, all hardware
196	registers are read whenever any data is read (unless it is less than 1.5
197	seconds since the last update). This means that you can easily miss
198	once-only alarms.
199	
200	Out-of-limit readings can also result in beeping, if the chip is properly
201	wired and configured. Beeping can be enabled or disabled per sensor type
202	(temperatures, voltages and fans.)
203	
204	The IT87xx only updates its values each 1.5 seconds; reading it more often
205	will do no harm, but will return 'old' values.
206	
207	To change sensor N to a thermistor, 'echo 4 > tempN_type' where N is 1, 2,
208	or 3. To change sensor N to a thermal diode, 'echo 3 > tempN_type'.
209	Give 0 for unused sensor. Any other value is invalid. To configure this at
210	startup, consult lm_sensors's /etc/sensors.conf. (4 = thermistor;
211	3 = thermal diode)
212	
213	
214	Fan speed control
215	-----------------
216	
217	The fan speed control features are limited to manual PWM mode. Automatic
218	"Smart Guardian" mode control handling is only implemented for older chips
219	(see below.) However if you want to go for "manual mode" just write 1 to
220	pwmN_enable.
221	
222	If you are only able to control the fan speed with very small PWM values,
223	try lowering the PWM base frequency (pwm1_freq). Depending on the fan,
224	it may give you a somewhat greater control range. The same frequency is
225	used to drive all fan outputs, which is why pwm2_freq and pwm3_freq are
226	read-only.
227	
228	
229	Automatic fan speed control (old interface)
230	-------------------------------------------
231	
232	The driver supports the old interface to automatic fan speed control
233	which is implemented by IT8705F chips up to revision F and IT8712F
234	chips up to revision G.
235	
236	This interface implements 4 temperature vs. PWM output trip points.
237	The PWM output of trip point 4 is always the maximum value (fan running
238	at full speed) while the PWM output of the other 3 trip points can be
239	freely chosen. The temperature of all 4 trip points can be freely chosen.
240	Additionally, trip point 1 has an hysteresis temperature attached, to
241	prevent fast switching between fan on and off.
242	
243	The chip automatically computes the PWM output value based on the input
244	temperature, based on this simple rule: if the temperature value is
245	between trip point N and trip point N+1 then the PWM output value is
246	the one of trip point N. The automatic control mode is less flexible
247	than the manual control mode, but it reacts faster, is more robust and
248	doesn't use CPU cycles.
249	
250	Trip points must be set properly before switching to automatic fan speed
251	control mode. The driver will perform basic integrity checks before
252	actually switching to automatic control mode.
253	
254	
255	Temperature offset attributes
256	-----------------------------
257	
258	The driver supports temp[1-3]_offset sysfs attributes to adjust the reported
259	temperature for thermal diodes or diode-connected thermal transistors.
260	If a temperature sensor is configured for thermistors, the attribute values
261	are ignored. If the thermal sensor type is Intel PECI, the temperature offset
262	must be programmed to the critical CPU temperature.
Hide Line Numbers
About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Information is copyright its respective author. All material is available from the Linux Kernel Source distributed under a GPL License. This page is provided as a free service by mjmwired.net.