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Linus Torvalds1da177e2005-04-16 15:20:36 -07001Kernel driver i2c-i801
2
3Supported 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)
Oleg Ryjkov7edcb9a2007-07-12 14:12:31 +02008 * Intel 82801DB (ICH4) (HW PEC supported)
9 * Intel 82801EB/ER (ICH5) (HW PEC supported)
Linus Torvalds1da177e2005-04-16 15:20:36 -070010 * Intel 6300ESB
11 * Intel 82801FB/FR/FW/FRW (ICH6)
Jason Gastona980a992006-12-10 21:21:31 +010012 * Intel 82801G (ICH7)
13 * Intel 631xESB/632xESB (ESB2)
14 * Intel 82801H (ICH8)
Gaston, Jason Dd28dc712008-02-24 20:03:42 +010015 * Intel 82801I (ICH9)
Seth Heasleyc429a242008-10-22 20:21:29 +020016 * Intel EP80579 (Tolapai)
17 * Intel 82801JI (ICH10)
Seth Heasleye30d9852010-10-31 21:06:59 +010018 * Intel 5/3400 Series (PCH)
Seth Heasley662cda82011-03-20 14:50:53 +010019 * Intel 6 Series (PCH)
Seth Heasleye30d9852010-10-31 21:06:59 +010020 * Intel Patsburg (PCH)
Seth Heasley662cda82011-03-20 14:50:53 +010021 * Intel DH89xxCC (PCH)
Seth Heasley6e2a8512011-05-24 20:58:49 +020022 * Intel Panther Point (PCH)
Seth Heasley062737f2012-03-26 21:47:19 +020023 * Intel Lynx Point (PCH)
James Ralston4a8f1dd2012-09-10 10:14:02 +020024 * Intel Lynx Point-LP (PCH)
Seth Heasleyc2db409c2013-01-30 15:25:32 +000025 * Intel Avoton (SOC)
James Ralstona3fc0ff2013-02-14 09:15:33 +000026 * Intel Wellsburg (PCH)
Seth Heasleyf39901c2013-06-19 16:59:57 -070027 * Intel Coleto Creek (PCH)
Jean Delvareb299de82014-07-17 15:04:41 +020028 * Intel Wildcat Point (PCH)
James Ralstonafc65922013-11-04 09:29:48 -080029 * Intel Wildcat Point-LP (PCH)
Chew, Kean ho1b31e9b2014-03-01 00:03:56 +080030 * Intel BayTrail (SOC)
james.d.ralston@intel.com3e27a842014-10-13 15:20:24 -070031 * Intel Sunrise Point-H (PCH)
Jason Gastone07bc672007-10-13 23:56:31 +020032 Datasheets: Publicly available at the Intel website
Linus Torvalds1da177e2005-04-16 15:20:36 -070033
David Woodhouse55fee8d2010-10-31 21:07:00 +010034On Intel Patsburg and later chipsets, both the normal host SMBus controller
35and the additional 'Integrated Device Function' controllers are supported.
36
Linus Torvalds1da177e2005-04-16 15:20:36 -070037Authors:
Linus Torvalds1da177e2005-04-16 15:20:36 -070038 Mark Studebaker <mdsxyz123@yahoo.com>
Jean Delvare7c81c602014-01-29 20:40:08 +010039 Jean Delvare <jdelvare@suse.de>
Linus Torvalds1da177e2005-04-16 15:20:36 -070040
41
42Module Parameters
43-----------------
44
Jean Delvareadff6872010-05-21 18:40:54 +020045* disable_features (bit vector)
46Disable selected features normally supported by the device. This makes it
47possible to work around possible driver or hardware bugs if the feature in
48question doesn't work as intended for whatever reason. Bit values:
Daniel Kurtz636752b2012-07-24 14:13:58 +020049 0x01 disable SMBus PEC
50 0x02 disable the block buffer
51 0x08 disable the I2C block read functionality
52 0x10 don't use interrupts
Linus Torvalds1da177e2005-04-16 15:20:36 -070053
54
55Description
56-----------
57
58The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA),
Seth Heasleyc429a242008-10-22 20:21:29 +020059ICH3 (82801CA/CAM) and later devices (PCH) are Intel chips that are a part of
Linus Torvalds1da177e2005-04-16 15:20:36 -070060Intel's '810' chipset for Celeron-based PCs, '810E' chipset for
61Pentium-based PCs, '815E' chipset, and others.
62
63The ICH chips contain at least SEVEN separate PCI functions in TWO logical
64PCI devices. An output of lspci will show something similar to the
65following:
66
67 00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01)
68 00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01)
69 00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01)
70 00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01)
71 00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01)
72
73The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial
74Controller.
75
Linus Torvalds1da177e2005-04-16 15:20:36 -070076The ICH chips are quite similar to Intel's PIIX4 chip, at least in the
77SMBus controller.
78
Linus Torvalds1da177e2005-04-16 15:20:36 -070079
80Process Call Support
81--------------------
82
83Not supported.
84
85
86I2C Block Read Support
87----------------------
88
Jean Delvare63420642008-01-27 18:14:50 +010089I2C block read is supported on the 82801EB (ICH5) and later chips.
Linus Torvalds1da177e2005-04-16 15:20:36 -070090
91
92SMBus 2.0 Support
93-----------------
94
95The 82801DB (ICH4) and later chips support several SMBus 2.0 features.
96
Jean Delvare099ab112007-02-13 22:09:00 +010097
Daniel Kurtz636752b2012-07-24 14:13:58 +020098Interrupt Support
99-----------------
100
101PCI interrupt support is supported on the 82801EB (ICH5) and later chips.
102
103
Jean Delvare099ab112007-02-13 22:09:00 +0100104Hidden ICH SMBus
105----------------
106
107If your system has an Intel ICH south bridge, but you do NOT see the
108SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the
109BIOS to enable it, it means it has been hidden by the BIOS code. Asus is
110well known for first doing this on their P4B motherboard, and many other
111boards after that. Some vendor machines are affected as well.
112
113The first thing to try is the "i2c_ec" ACPI driver. It could be that the
114SMBus was hidden on purpose because it'll be driven by ACPI. If the
115i2c_ec driver works for you, just forget about the i2c-i801 driver and
116don't try to unhide the ICH SMBus. Even if i2c_ec doesn't work, you
117better make sure that the SMBus isn't used by the ACPI code. Try loading
118the "fan" and "thermal" drivers, and check in /proc/acpi/fan and
119/proc/acpi/thermal_zone. If you find anything there, it's likely that
120the ACPI is accessing the SMBus and it's safer not to unhide it. Only
121once you are certain that ACPI isn't using the SMBus, you can attempt
122to unhide it.
123
124In order to unhide the SMBus, we need to change the value of a PCI
125register before the kernel enumerates the PCI devices. This is done in
126drivers/pci/quirks.c, where all affected boards must be listed (see
127function asus_hides_smbus_hostbridge.) If the SMBus device is missing,
128and you think there's something interesting on the SMBus (e.g. a
129hardware monitoring chip), you need to add your board to the list.
130
131The motherboard is identified using the subvendor and subdevice IDs of the
132host bridge PCI device. Get yours with "lspci -n -v -s 00:00.0":
133
13400:00.0 Class 0600: 8086:2570 (rev 02)
135 Subsystem: 1043:80f2
136 Flags: bus master, fast devsel, latency 0
137 Memory at fc000000 (32-bit, prefetchable) [size=32M]
138 Capabilities: [e4] #09 [2106]
139 Capabilities: [a0] AGP version 3.0
140
141Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043
142(Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic
143names for the bridge ID and the subvendor ID in include/linux/pci_ids.h,
144and then add a case for your subdevice ID at the right place in
145drivers/pci/quirks.c. Then please give it very good testing, to make sure
146that the unhidden SMBus doesn't conflict with e.g. ACPI.
147
148If it works, proves useful (i.e. there are usable chips on the SMBus)
149and seems safe, please submit a patch for inclusion into the kernel.
150
151Note: There's a useful script in lm_sensors 2.10.2 and later, named
152unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to
153temporarily unhide the SMBus without having to patch and recompile your
154kernel. It's very convenient if you just want to check if there's
155anything interesting on your hidden ICH SMBus.
156
157
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158**********************
159The lm_sensors project gratefully acknowledges the support of Texas
160Instruments in the initial development of this driver.
161
162The lm_sensors project gratefully acknowledges the support of Intel in the
163development of SMBus 2.0 / ICH4 features of this driver.