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 * Intel Arrow Lake (SOC) 52 * Intel Panther Lake (SOC) 53 54 Datasheets: Publicly available at the Intel website 55 56On Intel Patsburg and later chipsets, both the normal host SMBus controller 57and the additional 'Integrated Device Function' controllers are supported. 58 59Authors: 60 - Mark Studebaker <mdsxyz123@yahoo.com> 61 - Jean Delvare <jdelvare@suse.de> 62 63 64Module Parameters 65----------------- 66 67* disable_features (bit vector) 68 69Disable selected features normally supported by the device. This makes it 70possible to work around possible driver or hardware bugs if the feature in 71question doesn't work as intended for whatever reason. Bit values: 72 73 ==== ========================================= 74 0x01 disable SMBus PEC 75 0x02 disable the block buffer 76 0x08 disable the I2C block read functionality 77 0x10 don't use interrupts 78 0x20 disable SMBus Host Notify 79 ==== ========================================= 80 81 82Description 83----------- 84 85The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA), 86ICH3 (82801CA/CAM) and later devices (PCH) are Intel chips that are a part of 87Intel's '810' chipset for Celeron-based PCs, '810E' chipset for 88Pentium-based PCs, '815E' chipset, and others. 89 90The ICH chips contain at least SEVEN separate PCI functions in TWO logical 91PCI devices. An output of lspci will show something similar to the 92following:: 93 94 00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01) 95 00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01) 96 00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01) 97 00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01) 98 00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01) 99 100The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial 101Controller. 102 103The ICH chips are quite similar to Intel's PIIX4 chip, at least in the 104SMBus controller. 105 106 107Process Call Support 108-------------------- 109 110Block process call is supported on the 82801EB (ICH5) and later chips. 111 112 113I2C Block Read Support 114---------------------- 115 116I2C block read is supported on the 82801EB (ICH5) and later chips. 117 118 119SMBus 2.0 Support 120----------------- 121 122The 82801DB (ICH4) and later chips support several SMBus 2.0 features. 123 124 125Interrupt Support 126----------------- 127 128PCI interrupt support is supported on the 82801EB (ICH5) and later chips. 129 130 131Hidden ICH SMBus 132---------------- 133 134If your system has an Intel ICH south bridge, but you do NOT see the 135SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the 136BIOS to enable it, it means it has been hidden by the BIOS code. Asus is 137well known for first doing this on their P4B motherboard, and many other 138boards after that. Some vendor machines are affected as well. 139 140The first thing to try is the "i2c-scmi" ACPI driver. It could be that the 141SMBus was hidden on purpose because it'll be driven by ACPI. If the 142i2c-scmi driver works for you, just forget about the i2c-i801 driver and 143don't try to unhide the ICH SMBus. Even if i2c-scmi doesn't work, you 144better make sure that the SMBus isn't used by the ACPI code. Try loading 145the "fan" and "thermal" drivers, and check in /sys/class/thermal. If you 146find a thermal zone with type "acpitz", it's likely that the ACPI is 147accessing the SMBus and it's safer not to unhide it. Only once you are 148certain that ACPI isn't using the SMBus, you can attempt to unhide it. 149 150In order to unhide the SMBus, we need to change the value of a PCI 151register before the kernel enumerates the PCI devices. This is done in 152drivers/pci/quirks.c, where all affected boards must be listed (see 153function asus_hides_smbus_hostbridge.) If the SMBus device is missing, 154and you think there's something interesting on the SMBus (e.g. a 155hardware monitoring chip), you need to add your board to the list. 156 157The motherboard is identified using the subvendor and subdevice IDs of the 158host bridge PCI device. Get yours with ``lspci -n -v -s 00:00.0``:: 159 160 00:00.0 Class 0600: 8086:2570 (rev 02) 161 Subsystem: 1043:80f2 162 Flags: bus master, fast devsel, latency 0 163 Memory at fc000000 (32-bit, prefetchable) [size=32M] 164 Capabilities: [e4] #09 [2106] 165 Capabilities: [a0] AGP version 3.0 166 167Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043 168(Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic 169names for the bridge ID and the subvendor ID in include/linux/pci_ids.h, 170and then add a case for your subdevice ID at the right place in 171drivers/pci/quirks.c. Then please give it very good testing, to make sure 172that the unhidden SMBus doesn't conflict with e.g. ACPI. 173 174If it works, proves useful (i.e. there are usable chips on the SMBus) 175and seems safe, please submit a patch for inclusion into the kernel. 176 177Note: There's a useful script in lm_sensors 2.10.2 and later, named 178unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to 179temporarily unhide the SMBus without having to patch and recompile your 180kernel. It's very convenient if you just want to check if there's 181anything interesting on your hidden ICH SMBus. 182 183 184---------------------------------------------------------------------------- 185 186The lm_sensors project gratefully acknowledges the support of Texas 187Instruments in the initial development of this driver. 188 189The lm_sensors project gratefully acknowledges the support of Intel in the 190development of SMBus 2.0 / ICH4 features of this driver. 191