blob: d477024569269ff741720537ef609cafb60166f2 [file] [log] [blame]
rjw1f884582022-01-06 17:20:42 +08001Kernel 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)
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 (PCH)
29 * Intel Wildcat Point-LP (PCH)
30 * Intel BayTrail (SOC)
31 * Intel Sunrise Point-H (PCH)
32 * Intel Sunrise Point-LP (PCH)
33 * Intel DNV (SOC)
34 * Intel Broxton (SOC)
35 * Intel Lewisburg (PCH)
36 * Intel Gemini Lake (SOC)
37 * Intel Cannon Lake-H (PCH)
38 * Intel Cannon Lake-LP (PCH)
39 * Intel Cedar Fork (PCH)
40 Datasheets: Publicly available at the Intel website
41
42On Intel Patsburg and later chipsets, both the normal host SMBus controller
43and the additional 'Integrated Device Function' controllers are supported.
44
45Authors:
46 Mark Studebaker <mdsxyz123@yahoo.com>
47 Jean Delvare <jdelvare@suse.de>
48
49
50Module Parameters
51-----------------
52
53* disable_features (bit vector)
54Disable selected features normally supported by the device. This makes it
55possible to work around possible driver or hardware bugs if the feature in
56question doesn't work as intended for whatever reason. Bit values:
57 0x01 disable SMBus PEC
58 0x02 disable the block buffer
59 0x08 disable the I2C block read functionality
60 0x10 don't use interrupts
61
62
63Description
64-----------
65
66The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA),
67ICH3 (82801CA/CAM) and later devices (PCH) are Intel chips that are a part of
68Intel's '810' chipset for Celeron-based PCs, '810E' chipset for
69Pentium-based PCs, '815E' chipset, and others.
70
71The ICH chips contain at least SEVEN separate PCI functions in TWO logical
72PCI devices. An output of lspci will show something similar to the
73following:
74
75 00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01)
76 00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01)
77 00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01)
78 00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01)
79 00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01)
80
81The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial
82Controller.
83
84The ICH chips are quite similar to Intel's PIIX4 chip, at least in the
85SMBus controller.
86
87
88Process Call Support
89--------------------
90
91Not supported.
92
93
94I2C Block Read Support
95----------------------
96
97I2C block read is supported on the 82801EB (ICH5) and later chips.
98
99
100SMBus 2.0 Support
101-----------------
102
103The 82801DB (ICH4) and later chips support several SMBus 2.0 features.
104
105
106Interrupt Support
107-----------------
108
109PCI interrupt support is supported on the 82801EB (ICH5) and later chips.
110
111
112Hidden ICH SMBus
113----------------
114
115If your system has an Intel ICH south bridge, but you do NOT see the
116SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the
117BIOS to enable it, it means it has been hidden by the BIOS code. Asus is
118well known for first doing this on their P4B motherboard, and many other
119boards after that. Some vendor machines are affected as well.
120
121The first thing to try is the "i2c_ec" ACPI driver. It could be that the
122SMBus was hidden on purpose because it'll be driven by ACPI. If the
123i2c_ec driver works for you, just forget about the i2c-i801 driver and
124don't try to unhide the ICH SMBus. Even if i2c_ec doesn't work, you
125better make sure that the SMBus isn't used by the ACPI code. Try loading
126the "fan" and "thermal" drivers, and check in /proc/acpi/fan and
127/proc/acpi/thermal_zone. If you find anything there, it's likely that
128the ACPI is accessing the SMBus and it's safer not to unhide it. Only
129once you are certain that ACPI isn't using the SMBus, you can attempt
130to unhide it.
131
132In order to unhide the SMBus, we need to change the value of a PCI
133register before the kernel enumerates the PCI devices. This is done in
134drivers/pci/quirks.c, where all affected boards must be listed (see
135function asus_hides_smbus_hostbridge.) If the SMBus device is missing,
136and you think there's something interesting on the SMBus (e.g. a
137hardware monitoring chip), you need to add your board to the list.
138
139The motherboard is identified using the subvendor and subdevice IDs of the
140host bridge PCI device. Get yours with "lspci -n -v -s 00:00.0":
141
14200:00.0 Class 0600: 8086:2570 (rev 02)
143 Subsystem: 1043:80f2
144 Flags: bus master, fast devsel, latency 0
145 Memory at fc000000 (32-bit, prefetchable) [size=32M]
146 Capabilities: [e4] #09 [2106]
147 Capabilities: [a0] AGP version 3.0
148
149Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043
150(Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic
151names for the bridge ID and the subvendor ID in include/linux/pci_ids.h,
152and then add a case for your subdevice ID at the right place in
153drivers/pci/quirks.c. Then please give it very good testing, to make sure
154that the unhidden SMBus doesn't conflict with e.g. ACPI.
155
156If it works, proves useful (i.e. there are usable chips on the SMBus)
157and seems safe, please submit a patch for inclusion into the kernel.
158
159Note: There's a useful script in lm_sensors 2.10.2 and later, named
160unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to
161temporarily unhide the SMBus without having to patch and recompile your
162kernel. It's very convenient if you just want to check if there's
163anything interesting on your hidden ICH SMBus.
164
165
166**********************
167The lm_sensors project gratefully acknowledges the support of Texas
168Instruments in the initial development of this driver.
169
170The lm_sensors project gratefully acknowledges the support of Intel in the
171development of SMBus 2.0 / ICH4 features of this driver.