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Based on kernel version 3.13. Page generated on 2014-01-20 22:03 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	   Datasheets: Publicly available at the Intel website
30	
31	On Intel Patsburg and later chipsets, both the normal host SMBus controller
32	and the additional 'Integrated Device Function' controllers are supported.
33	
34	Authors: 
35		Mark Studebaker <mdsxyz123@yahoo.com>
36		Jean Delvare <khali@linux-fr.org>
37	
38	
39	Module Parameters
40	-----------------
41	
42	* disable_features (bit vector)
43	Disable selected features normally supported by the device. This makes it
44	possible to work around possible driver or hardware bugs if the feature in
45	question doesn't work as intended for whatever reason. Bit values:
46	 0x01  disable SMBus PEC
47	 0x02  disable the block buffer
48	 0x08  disable the I2C block read functionality
49	 0x10  don't use interrupts
50	
51	
52	Description
53	-----------
54	
55	The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA),
56	ICH3 (82801CA/CAM) and later devices (PCH) are Intel chips that are a part of
57	Intel's '810' chipset for Celeron-based PCs, '810E' chipset for
58	Pentium-based PCs, '815E' chipset, and others.
59	
60	The ICH chips contain at least SEVEN separate PCI functions in TWO logical
61	PCI devices. An output of lspci will show something similar to the
62	following:
63	
64	  00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01)
65	  00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01)
66	  00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01)
67	  00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01)
68	  00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01)
69	
70	The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial
71	Controller.
72	
73	The ICH chips are quite similar to Intel's PIIX4 chip, at least in the
74	SMBus controller.
75	
76	
77	Process Call Support
78	--------------------
79	
80	Not supported.
81	
82	
83	I2C Block Read Support
84	----------------------
85	
86	I2C block read is supported on the 82801EB (ICH5) and later chips.
87	
88	
89	SMBus 2.0 Support
90	-----------------
91	
92	The 82801DB (ICH4) and later chips support several SMBus 2.0 features.
93	
94	
95	Interrupt Support
96	-----------------
97	
98	PCI interrupt support is supported on the 82801EB (ICH5) and later chips.
99	
100	
101	Hidden ICH SMBus
102	----------------
103	
104	If your system has an Intel ICH south bridge, but you do NOT see the
105	SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the
106	BIOS to enable it, it means it has been hidden by the BIOS code. Asus is
107	well known for first doing this on their P4B motherboard, and many other
108	boards after that. Some vendor machines are affected as well.
109	
110	The first thing to try is the "i2c_ec" ACPI driver. It could be that the
111	SMBus was hidden on purpose because it'll be driven by ACPI. If the
112	i2c_ec driver works for you, just forget about the i2c-i801 driver and
113	don't try to unhide the ICH SMBus. Even if i2c_ec doesn't work, you
114	better make sure that the SMBus isn't used by the ACPI code. Try loading
115	the "fan" and "thermal" drivers, and check in /proc/acpi/fan and
116	/proc/acpi/thermal_zone. If you find anything there, it's likely that
117	the ACPI is accessing the SMBus and it's safer not to unhide it. Only
118	once you are certain that ACPI isn't using the SMBus, you can attempt
119	to unhide it.
120	
121	In order to unhide the SMBus, we need to change the value of a PCI
122	register before the kernel enumerates the PCI devices. This is done in
123	drivers/pci/quirks.c, where all affected boards must be listed (see
124	function asus_hides_smbus_hostbridge.) If the SMBus device is missing,
125	and you think there's something interesting on the SMBus (e.g. a
126	hardware monitoring chip), you need to add your board to the list.
127	
128	The motherboard is identified using the subvendor and subdevice IDs of the
129	host bridge PCI device. Get yours with "lspci -n -v -s 00:00.0":
130	
131	00:00.0 Class 0600: 8086:2570 (rev 02)
132	        Subsystem: 1043:80f2
133	        Flags: bus master, fast devsel, latency 0
134	        Memory at fc000000 (32-bit, prefetchable) [size=32M]
135	        Capabilities: [e4] #09 [2106]
136	        Capabilities: [a0] AGP version 3.0
137	
138	Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043
139	(Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic
140	names for the bridge ID and the subvendor ID in include/linux/pci_ids.h,
141	and then add a case for your subdevice ID at the right place in
142	drivers/pci/quirks.c. Then please give it very good testing, to make sure
143	that the unhidden SMBus doesn't conflict with e.g. ACPI.
144	
145	If it works, proves useful (i.e. there are usable chips on the SMBus)
146	and seems safe, please submit a patch for inclusion into the kernel.
147	
148	Note: There's a useful script in lm_sensors 2.10.2 and later, named
149	unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to
150	temporarily unhide the SMBus without having to patch and recompile your
151	kernel. It's very convenient if you just want to check if there's
152	anything interesting on your hidden ICH SMBus.
153	
154	
155	**********************
156	The lm_sensors project gratefully acknowledges the support of Texas
157	Instruments in the initial development of this driver.
158	
159	The lm_sensors project gratefully acknowledges the support of Intel in the
160	development of SMBus 2.0 / ICH4 features of this driver.
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