1====================== 2Kernel driver i2c-i801 3====================== 4 5 6Supported adapters: 7 * Intel 82801AA and 82801AB (ICH and ICH0 - part of the 8 '810' and '810E' chipsets) 9 * Intel 82801BA (ICH2 - part of the '815E' chipset) 10 * Intel 82801CA/CAM (ICH3) 11 * Intel 82801DB (ICH4) (HW PEC supported) 12 * Intel 82801EB/ER (ICH5) (HW PEC supported) 13 * Intel 6300ESB 14 * Intel 82801FB/FR/FW/FRW (ICH6) 15 * Intel 82801G (ICH7) 16 * Intel 631xESB/632xESB (ESB2) 17 * Intel 82801H (ICH8) 18 * Intel 82801I (ICH9) 19 * Intel EP80579 (Tolapai) 20 * Intel 82801JI (ICH10) 21 * Intel 5/3400 Series (PCH) 22 * Intel 6 Series (PCH) 23 * Intel Patsburg (PCH) 24 * Intel DH89xxCC (PCH) 25 * Intel Panther Point (PCH) 26 * Intel Lynx Point (PCH) 27 * Intel Avoton (SOC) 28 * Intel Wellsburg (PCH) 29 * Intel Coleto Creek (PCH) 30 * Intel Wildcat Point (PCH) 31 * Intel BayTrail (SOC) 32 * Intel Braswell (SOC) 33 * Intel Sunrise Point (PCH) 34 * Intel Kaby Lake (PCH) 35 * Intel DNV (SOC) 36 * Intel Broxton (SOC) 37 * Intel Lewisburg (PCH) 38 * Intel Gemini Lake (SOC) 39 * Intel Cannon Lake (PCH) 40 * Intel Cedar Fork (PCH) 41 * Intel Ice Lake (PCH) 42 * Intel Comet Lake (PCH) 43 * Intel Elkhart Lake (PCH) 44 * Intel Tiger Lake (PCH) 45 * Intel Jasper Lake (SOC) 46 * Intel Emmitsburg (PCH) 47 * Intel Alder Lake (PCH) 48 49 Datasheets: Publicly available at the Intel website 50 51On Intel Patsburg and later chipsets, both the normal host SMBus controller 52and the additional 'Integrated Device Function' controllers are supported. 53 54Authors: 55 - Mark Studebaker <mdsxyz123@yahoo.com> 56 - Jean Delvare <jdelvare@suse.de> 57 58 59Module Parameters 60----------------- 61 62* disable_features (bit vector) 63 64Disable selected features normally supported by the device. This makes it 65possible to work around possible driver or hardware bugs if the feature in 66question doesn't work as intended for whatever reason. Bit values: 67 68 ==== ========================================= 69 0x01 disable SMBus PEC 70 0x02 disable the block buffer 71 0x08 disable the I2C block read functionality 72 0x10 don't use interrupts 73 0x20 disable SMBus Host Notify 74 ==== ========================================= 75 76 77Description 78----------- 79 80The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA), 81ICH3 (82801CA/CAM) and later devices (PCH) are Intel chips that are a part of 82Intel's '810' chipset for Celeron-based PCs, '810E' chipset for 83Pentium-based PCs, '815E' chipset, and others. 84 85The ICH chips contain at least SEVEN separate PCI functions in TWO logical 86PCI devices. An output of lspci will show something similar to the 87following:: 88 89 00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01) 90 00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01) 91 00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01) 92 00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01) 93 00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01) 94 95The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial 96Controller. 97 98The ICH chips are quite similar to Intel's PIIX4 chip, at least in the 99SMBus controller. 100 101 102Process Call Support 103-------------------- 104 105Block process call is supported on the 82801EB (ICH5) and later chips. 106 107 108I2C Block Read Support 109---------------------- 110 111I2C block read is supported on the 82801EB (ICH5) and later chips. 112 113 114SMBus 2.0 Support 115----------------- 116 117The 82801DB (ICH4) and later chips support several SMBus 2.0 features. 118 119 120Interrupt Support 121----------------- 122 123PCI interrupt support is supported on the 82801EB (ICH5) and later chips. 124 125 126Hidden ICH SMBus 127---------------- 128 129If your system has an Intel ICH south bridge, but you do NOT see the 130SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the 131BIOS to enable it, it means it has been hidden by the BIOS code. Asus is 132well known for first doing this on their P4B motherboard, and many other 133boards after that. Some vendor machines are affected as well. 134 135The first thing to try is the "i2c-scmi" ACPI driver. It could be that the 136SMBus was hidden on purpose because it'll be driven by ACPI. If the 137i2c-scmi driver works for you, just forget about the i2c-i801 driver and 138don't try to unhide the ICH SMBus. Even if i2c-scmi doesn't work, you 139better make sure that the SMBus isn't used by the ACPI code. Try loading 140the "fan" and "thermal" drivers, and check in /sys/class/thermal. If you 141find a thermal zone with type "acpitz", it's likely that the ACPI is 142accessing the SMBus and it's safer not to unhide it. Only once you are 143certain that ACPI isn't using the SMBus, you can attempt to unhide it. 144 145In order to unhide the SMBus, we need to change the value of a PCI 146register before the kernel enumerates the PCI devices. This is done in 147drivers/pci/quirks.c, where all affected boards must be listed (see 148function asus_hides_smbus_hostbridge.) If the SMBus device is missing, 149and you think there's something interesting on the SMBus (e.g. a 150hardware monitoring chip), you need to add your board to the list. 151 152The motherboard is identified using the subvendor and subdevice IDs of the 153host bridge PCI device. Get yours with ``lspci -n -v -s 00:00.0``:: 154 155 00:00.0 Class 0600: 8086:2570 (rev 02) 156 Subsystem: 1043:80f2 157 Flags: bus master, fast devsel, latency 0 158 Memory at fc000000 (32-bit, prefetchable) [size=32M] 159 Capabilities: [e4] #09 [2106] 160 Capabilities: [a0] AGP version 3.0 161 162Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043 163(Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic 164names for the bridge ID and the subvendor ID in include/linux/pci_ids.h, 165and then add a case for your subdevice ID at the right place in 166drivers/pci/quirks.c. Then please give it very good testing, to make sure 167that the unhidden SMBus doesn't conflict with e.g. ACPI. 168 169If it works, proves useful (i.e. there are usable chips on the SMBus) 170and seems safe, please submit a patch for inclusion into the kernel. 171 172Note: There's a useful script in lm_sensors 2.10.2 and later, named 173unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to 174temporarily unhide the SMBus without having to patch and recompile your 175kernel. It's very convenient if you just want to check if there's 176anything interesting on your hidden ICH SMBus. 177 178 179---------------------------------------------------------------------------- 180 181The lm_sensors project gratefully acknowledges the support of Texas 182Instruments in the initial development of this driver. 183 184The lm_sensors project gratefully acknowledges the support of Intel in the 185development of SMBus 2.0 / ICH4 features of this driver. 186