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 * Intel Meteor Lake (SOC and PCH) 50 * Intel Birch Stream (SOC) 51 52 Datasheets: Publicly available at the Intel website 53 54On Intel Patsburg and later chipsets, both the normal host SMBus controller 55and the additional 'Integrated Device Function' controllers are supported. 56 57Authors: 58 - Mark Studebaker <mdsxyz123@yahoo.com> 59 - Jean Delvare <jdelvare@suse.de> 60 61 62Module Parameters 63----------------- 64 65* disable_features (bit vector) 66 67Disable selected features normally supported by the device. This makes it 68possible to work around possible driver or hardware bugs if the feature in 69question doesn't work as intended for whatever reason. Bit values: 70 71 ==== ========================================= 72 0x01 disable SMBus PEC 73 0x02 disable the block buffer 74 0x08 disable the I2C block read functionality 75 0x10 don't use interrupts 76 0x20 disable SMBus Host Notify 77 ==== ========================================= 78 79 80Description 81----------- 82 83The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA), 84ICH3 (82801CA/CAM) and later devices (PCH) are Intel chips that are a part of 85Intel's '810' chipset for Celeron-based PCs, '810E' chipset for 86Pentium-based PCs, '815E' chipset, and others. 87 88The ICH chips contain at least SEVEN separate PCI functions in TWO logical 89PCI devices. An output of lspci will show something similar to the 90following:: 91 92 00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01) 93 00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01) 94 00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01) 95 00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01) 96 00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01) 97 98The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial 99Controller. 100 101The ICH chips are quite similar to Intel's PIIX4 chip, at least in the 102SMBus controller. 103 104 105Process Call Support 106-------------------- 107 108Block process call is supported on the 82801EB (ICH5) and later chips. 109 110 111I2C Block Read Support 112---------------------- 113 114I2C block read is supported on the 82801EB (ICH5) and later chips. 115 116 117SMBus 2.0 Support 118----------------- 119 120The 82801DB (ICH4) and later chips support several SMBus 2.0 features. 121 122 123Interrupt Support 124----------------- 125 126PCI interrupt support is supported on the 82801EB (ICH5) and later chips. 127 128 129Hidden ICH SMBus 130---------------- 131 132If your system has an Intel ICH south bridge, but you do NOT see the 133SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the 134BIOS to enable it, it means it has been hidden by the BIOS code. Asus is 135well known for first doing this on their P4B motherboard, and many other 136boards after that. Some vendor machines are affected as well. 137 138The first thing to try is the "i2c-scmi" ACPI driver. It could be that the 139SMBus was hidden on purpose because it'll be driven by ACPI. If the 140i2c-scmi driver works for you, just forget about the i2c-i801 driver and 141don't try to unhide the ICH SMBus. Even if i2c-scmi doesn't work, you 142better make sure that the SMBus isn't used by the ACPI code. Try loading 143the "fan" and "thermal" drivers, and check in /sys/class/thermal. If you 144find a thermal zone with type "acpitz", it's likely that the ACPI is 145accessing the SMBus and it's safer not to unhide it. Only once you are 146certain that ACPI isn't using the SMBus, you can attempt to unhide it. 147 148In order to unhide the SMBus, we need to change the value of a PCI 149register before the kernel enumerates the PCI devices. This is done in 150drivers/pci/quirks.c, where all affected boards must be listed (see 151function asus_hides_smbus_hostbridge.) If the SMBus device is missing, 152and you think there's something interesting on the SMBus (e.g. a 153hardware monitoring chip), you need to add your board to the list. 154 155The motherboard is identified using the subvendor and subdevice IDs of the 156host bridge PCI device. Get yours with ``lspci -n -v -s 00:00.0``:: 157 158 00:00.0 Class 0600: 8086:2570 (rev 02) 159 Subsystem: 1043:80f2 160 Flags: bus master, fast devsel, latency 0 161 Memory at fc000000 (32-bit, prefetchable) [size=32M] 162 Capabilities: [e4] #09 [2106] 163 Capabilities: [a0] AGP version 3.0 164 165Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043 166(Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic 167names for the bridge ID and the subvendor ID in include/linux/pci_ids.h, 168and then add a case for your subdevice ID at the right place in 169drivers/pci/quirks.c. Then please give it very good testing, to make sure 170that the unhidden SMBus doesn't conflict with e.g. ACPI. 171 172If it works, proves useful (i.e. there are usable chips on the SMBus) 173and seems safe, please submit a patch for inclusion into the kernel. 174 175Note: There's a useful script in lm_sensors 2.10.2 and later, named 176unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to 177temporarily unhide the SMBus without having to patch and recompile your 178kernel. It's very convenient if you just want to check if there's 179anything interesting on your hidden ICH SMBus. 180 181 182---------------------------------------------------------------------------- 183 184The lm_sensors project gratefully acknowledges the support of Texas 185Instruments in the initial development of this driver. 186 187The lm_sensors project gratefully acknowledges the support of Intel in the 188development of SMBus 2.0 / ICH4 features of this driver. 189