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