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)
11 * Intel 82801FB/FR/FW/FRW (ICH6)
13 * Intel 631xESB/632xESB (ESB2)
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)
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
32 On Intel Patsburg and later chipsets, both the normal host SMBus controller
33 and the additional 'Integrated Device Function' controllers are supported.
36 Mark Studebaker <mdsxyz123@yahoo.com>
37 Jean Delvare <jdelvare@suse.de>
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
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.
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
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)
71 The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial
74 The ICH chips are quite similar to Intel's PIIX4 chip, at least in the
84 I2C Block Read Support
85 ----------------------
87 I2C block read is supported on the 82801EB (ICH5) and later chips.
93 The 82801DB (ICH4) and later chips support several SMBus 2.0 features.
99 PCI interrupt support is supported on the 82801EB (ICH5) and later chips.
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.
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
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.
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":
132 00:00.0 Class 0600: 8086:2570 (rev 02)
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
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.
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.
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.
156 **********************
157 The lm_sensors project gratefully acknowledges the support of Texas
158 Instruments in the initial development of this driver.
160 The lm_sensors project gratefully acknowledges the support of Intel in the
161 development of SMBus 2.0 / ICH4 features of this driver.