i2c-i801.rst (6679B)
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 * Intel Raptor Lake (PCH) 49 50 Datasheets: Publicly available at the Intel website 51 52On Intel Patsburg and later chipsets, both the normal host SMBus controller 53and the additional 'Integrated Device Function' controllers are supported. 54 55Authors: 56 - Mark Studebaker <mdsxyz123@yahoo.com> 57 - Jean Delvare <jdelvare@suse.de> 58 59 60Module Parameters 61----------------- 62 63* disable_features (bit vector) 64 65Disable selected features normally supported by the device. This makes it 66possible to work around possible driver or hardware bugs if the feature in 67question doesn't work as intended for whatever reason. Bit values: 68 69 ==== ========================================= 70 0x01 disable SMBus PEC 71 0x02 disable the block buffer 72 0x08 disable the I2C block read functionality 73 0x10 don't use interrupts 74 0x20 disable SMBus Host Notify 75 ==== ========================================= 76 77 78Description 79----------- 80 81The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA), 82ICH3 (82801CA/CAM) and later devices (PCH) are Intel chips that are a part of 83Intel's '810' chipset for Celeron-based PCs, '810E' chipset for 84Pentium-based PCs, '815E' chipset, and others. 85 86The ICH chips contain at least SEVEN separate PCI functions in TWO logical 87PCI devices. An output of lspci will show something similar to the 88following:: 89 90 00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01) 91 00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01) 92 00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01) 93 00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01) 94 00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01) 95 96The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial 97Controller. 98 99The ICH chips are quite similar to Intel's PIIX4 chip, at least in the 100SMBus controller. 101 102 103Process Call Support 104-------------------- 105 106Block process call is supported on the 82801EB (ICH5) and later chips. 107 108 109I2C Block Read Support 110---------------------- 111 112I2C block read is supported on the 82801EB (ICH5) and later chips. 113 114 115SMBus 2.0 Support 116----------------- 117 118The 82801DB (ICH4) and later chips support several SMBus 2.0 features. 119 120 121Interrupt Support 122----------------- 123 124PCI interrupt support is supported on the 82801EB (ICH5) and later chips. 125 126 127Hidden ICH SMBus 128---------------- 129 130If your system has an Intel ICH south bridge, but you do NOT see the 131SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the 132BIOS to enable it, it means it has been hidden by the BIOS code. Asus is 133well known for first doing this on their P4B motherboard, and many other 134boards after that. Some vendor machines are affected as well. 135 136The first thing to try is the "i2c-scmi" ACPI driver. It could be that the 137SMBus was hidden on purpose because it'll be driven by ACPI. If the 138i2c-scmi driver works for you, just forget about the i2c-i801 driver and 139don't try to unhide the ICH SMBus. Even if i2c-scmi doesn't work, you 140better make sure that the SMBus isn't used by the ACPI code. Try loading 141the "fan" and "thermal" drivers, and check in /sys/class/thermal. If you 142find a thermal zone with type "acpitz", it's likely that the ACPI is 143accessing the SMBus and it's safer not to unhide it. Only once you are 144certain that ACPI isn't using the SMBus, you can attempt to unhide it. 145 146In order to unhide the SMBus, we need to change the value of a PCI 147register before the kernel enumerates the PCI devices. This is done in 148drivers/pci/quirks.c, where all affected boards must be listed (see 149function asus_hides_smbus_hostbridge.) If the SMBus device is missing, 150and you think there's something interesting on the SMBus (e.g. a 151hardware monitoring chip), you need to add your board to the list. 152 153The motherboard is identified using the subvendor and subdevice IDs of the 154host bridge PCI device. Get yours with ``lspci -n -v -s 00:00.0``:: 155 156 00:00.0 Class 0600: 8086:2570 (rev 02) 157 Subsystem: 1043:80f2 158 Flags: bus master, fast devsel, latency 0 159 Memory at fc000000 (32-bit, prefetchable) [size=32M] 160 Capabilities: [e4] #09 [2106] 161 Capabilities: [a0] AGP version 3.0 162 163Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043 164(Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic 165names for the bridge ID and the subvendor ID in include/linux/pci_ids.h, 166and then add a case for your subdevice ID at the right place in 167drivers/pci/quirks.c. Then please give it very good testing, to make sure 168that the unhidden SMBus doesn't conflict with e.g. ACPI. 169 170If it works, proves useful (i.e. there are usable chips on the SMBus) 171and seems safe, please submit a patch for inclusion into the kernel. 172 173Note: There's a useful script in lm_sensors 2.10.2 and later, named 174unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to 175temporarily unhide the SMBus without having to patch and recompile your 176kernel. It's very convenient if you just want to check if there's 177anything interesting on your hidden ICH SMBus. 178 179 180---------------------------------------------------------------------------- 181 182The lm_sensors project gratefully acknowledges the support of Texas 183Instruments in the initial development of this driver. 184 185The lm_sensors project gratefully acknowledges the support of Intel in the 186development of SMBus 2.0 / ICH4 features of this driver.