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Based on kernel version 3.15.4. Page generated on 2014-07-07 09:03 EST.

1	Kernel driver i2c-i801
2	
3	Supported adapters:
4	  * Intel 82801AA and 82801AB (ICH and ICH0 - part of the
5	    '810' and '810E' chipsets)
6	  * Intel 82801BA (ICH2 - part of the '815E' chipset)
7	  * Intel 82801CA/CAM (ICH3)
8	  * Intel 82801DB (ICH4) (HW PEC supported)
9	  * Intel 82801EB/ER (ICH5) (HW PEC supported)
10	  * Intel 6300ESB
11	  * Intel 82801FB/FR/FW/FRW (ICH6)
12	  * Intel 82801G (ICH7)
13	  * Intel 631xESB/632xESB (ESB2)
14	  * Intel 82801H (ICH8)
15	  * Intel 82801I (ICH9)
16	  * Intel EP80579 (Tolapai)
17	  * Intel 82801JI (ICH10)
18	  * Intel 5/3400 Series (PCH)
19	  * Intel 6 Series (PCH)
20	  * Intel Patsburg (PCH)
21	  * Intel DH89xxCC (PCH)
22	  * Intel Panther Point (PCH)
23	  * Intel Lynx Point (PCH)
24	  * Intel Lynx Point-LP (PCH)
25	  * Intel Avoton (SOC)
26	  * Intel Wellsburg (PCH)
27	  * Intel Coleto Creek (PCH)
28	  * Intel Wildcat Point-LP (PCH)
29	  * Intel BayTrail (SOC)
30	   Datasheets: Publicly available at the Intel website
31	
32	On Intel Patsburg and later chipsets, both the normal host SMBus controller
33	and the additional 'Integrated Device Function' controllers are supported.
34	
35	Authors: 
36		Mark Studebaker <mdsxyz123@yahoo.com>
37		Jean Delvare <jdelvare@suse.de>
38	
39	
40	Module Parameters
41	-----------------
42	
43	* disable_features (bit vector)
44	Disable selected features normally supported by the device. This makes it
45	possible to work around possible driver or hardware bugs if the feature in
46	question doesn't work as intended for whatever reason. Bit values:
47	 0x01  disable SMBus PEC
48	 0x02  disable the block buffer
49	 0x08  disable the I2C block read functionality
50	 0x10  don't use interrupts
51	
52	
53	Description
54	-----------
55	
56	The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA),
57	ICH3 (82801CA/CAM) and later devices (PCH) are Intel chips that are a part of
58	Intel's '810' chipset for Celeron-based PCs, '810E' chipset for
59	Pentium-based PCs, '815E' chipset, and others.
60	
61	The ICH chips contain at least SEVEN separate PCI functions in TWO logical
62	PCI devices. An output of lspci will show something similar to the
63	following:
64	
65	  00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01)
66	  00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01)
67	  00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01)
68	  00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01)
69	  00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01)
70	
71	The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial
72	Controller.
73	
74	The ICH chips are quite similar to Intel's PIIX4 chip, at least in the
75	SMBus controller.
76	
77	
78	Process Call Support
79	--------------------
80	
81	Not supported.
82	
83	
84	I2C Block Read Support
85	----------------------
86	
87	I2C block read is supported on the 82801EB (ICH5) and later chips.
88	
89	
90	SMBus 2.0 Support
91	-----------------
92	
93	The 82801DB (ICH4) and later chips support several SMBus 2.0 features.
94	
95	
96	Interrupt Support
97	-----------------
98	
99	PCI interrupt support is supported on the 82801EB (ICH5) and later chips.
100	
101	
102	Hidden ICH SMBus
103	----------------
104	
105	If your system has an Intel ICH south bridge, but you do NOT see the
106	SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the
107	BIOS to enable it, it means it has been hidden by the BIOS code. Asus is
108	well known for first doing this on their P4B motherboard, and many other
109	boards after that. Some vendor machines are affected as well.
110	
111	The first thing to try is the "i2c_ec" ACPI driver. It could be that the
112	SMBus was hidden on purpose because it'll be driven by ACPI. If the
113	i2c_ec driver works for you, just forget about the i2c-i801 driver and
114	don't try to unhide the ICH SMBus. Even if i2c_ec doesn't work, you
115	better make sure that the SMBus isn't used by the ACPI code. Try loading
116	the "fan" and "thermal" drivers, and check in /proc/acpi/fan and
117	/proc/acpi/thermal_zone. If you find anything there, it's likely that
118	the ACPI is accessing the SMBus and it's safer not to unhide it. Only
119	once you are certain that ACPI isn't using the SMBus, you can attempt
120	to unhide it.
121	
122	In order to unhide the SMBus, we need to change the value of a PCI
123	register before the kernel enumerates the PCI devices. This is done in
124	drivers/pci/quirks.c, where all affected boards must be listed (see
125	function asus_hides_smbus_hostbridge.) If the SMBus device is missing,
126	and you think there's something interesting on the SMBus (e.g. a
127	hardware monitoring chip), you need to add your board to the list.
128	
129	The motherboard is identified using the subvendor and subdevice IDs of the
130	host bridge PCI device. Get yours with "lspci -n -v -s 00:00.0":
131	
132	00:00.0 Class 0600: 8086:2570 (rev 02)
133	        Subsystem: 1043:80f2
134	        Flags: bus master, fast devsel, latency 0
135	        Memory at fc000000 (32-bit, prefetchable) [size=32M]
136	        Capabilities: [e4] #09 [2106]
137	        Capabilities: [a0] AGP version 3.0
138	
139	Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043
140	(Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic
141	names for the bridge ID and the subvendor ID in include/linux/pci_ids.h,
142	and then add a case for your subdevice ID at the right place in
143	drivers/pci/quirks.c. Then please give it very good testing, to make sure
144	that the unhidden SMBus doesn't conflict with e.g. ACPI.
145	
146	If it works, proves useful (i.e. there are usable chips on the SMBus)
147	and seems safe, please submit a patch for inclusion into the kernel.
148	
149	Note: There's a useful script in lm_sensors 2.10.2 and later, named
150	unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to
151	temporarily unhide the SMBus without having to patch and recompile your
152	kernel. It's very convenient if you just want to check if there's
153	anything interesting on your hidden ICH SMBus.
154	
155	
156	**********************
157	The lm_sensors project gratefully acknowledges the support of Texas
158	Instruments in the initial development of this driver.
159	
160	The lm_sensors project gratefully acknowledges the support of Intel in the
161	development of SMBus 2.0 / ICH4 features of this driver.
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