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 * Intel Wildcat Lake (SOC) 54 * Intel Diamond Rapids (SOC) 55 56 Datasheets: Publicly available at the Intel website 57 58On Intel Patsburg and later chipsets, both the normal host SMBus controller 59and the additional 'Integrated Device Function' controllers are supported. 60 61Authors: 62 - Mark Studebaker <mdsxyz123@yahoo.com> 63 - Jean Delvare <jdelvare@suse.de> 64 65 66Module Parameters 67----------------- 68 69* disable_features (bit vector) 70 71Disable selected features normally supported by the device. This makes it 72possible to work around possible driver or hardware bugs if the feature in 73question doesn't work as intended for whatever reason. Bit values: 74 75 ==== ========================================= 76 0x01 disable SMBus PEC 77 0x02 disable the block buffer 78 0x08 disable the I2C block read functionality 79 0x10 don't use interrupts 80 0x20 disable SMBus Host Notify 81 ==== ========================================= 82 83 84Description 85----------- 86 87The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA), 88ICH3 (82801CA/CAM) and later devices (PCH) are Intel chips that are a part of 89Intel's '810' chipset for Celeron-based PCs, '810E' chipset for 90Pentium-based PCs, '815E' chipset, and others. 91 92The ICH chips contain at least SEVEN separate PCI functions in TWO logical 93PCI devices. An output of lspci will show something similar to the 94following:: 95 96 00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01) 97 00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01) 98 00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01) 99 00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01) 100 00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01) 101 102The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial 103Controller. 104 105The ICH chips are quite similar to Intel's PIIX4 chip, at least in the 106SMBus controller. 107 108 109Process Call Support 110-------------------- 111 112Block process call is supported on the 82801EB (ICH5) and later chips. 113 114 115I2C Block Read Support 116---------------------- 117 118I2C block read is supported on the 82801EB (ICH5) and later chips. 119 120 121SMBus 2.0 Support 122----------------- 123 124The 82801DB (ICH4) and later chips support several SMBus 2.0 features. 125 126 127Interrupt Support 128----------------- 129 130PCI interrupt support is supported on the 82801EB (ICH5) and later chips. 131 132 133Hidden ICH SMBus 134---------------- 135 136If your system has an Intel ICH south bridge, but you do NOT see the 137SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the 138BIOS to enable it, it means it has been hidden by the BIOS code. Asus is 139well known for first doing this on their P4B motherboard, and many other 140boards after that. Some vendor machines are affected as well. 141 142The first thing to try is the "i2c-scmi" ACPI driver. It could be that the 143SMBus was hidden on purpose because it'll be driven by ACPI. If the 144i2c-scmi driver works for you, just forget about the i2c-i801 driver and 145don't try to unhide the ICH SMBus. Even if i2c-scmi doesn't work, you 146better make sure that the SMBus isn't used by the ACPI code. Try loading 147the "fan" and "thermal" drivers, and check in /sys/class/thermal. If you 148find a thermal zone with type "acpitz", it's likely that the ACPI is 149accessing the SMBus and it's safer not to unhide it. Only once you are 150certain that ACPI isn't using the SMBus, you can attempt to unhide it. 151 152In order to unhide the SMBus, we need to change the value of a PCI 153register before the kernel enumerates the PCI devices. This is done in 154drivers/pci/quirks.c, where all affected boards must be listed (see 155function asus_hides_smbus_hostbridge.) If the SMBus device is missing, 156and you think there's something interesting on the SMBus (e.g. a 157hardware monitoring chip), you need to add your board to the list. 158 159The motherboard is identified using the subvendor and subdevice IDs of the 160host bridge PCI device. Get yours with ``lspci -n -v -s 00:00.0``:: 161 162 00:00.0 Class 0600: 8086:2570 (rev 02) 163 Subsystem: 1043:80f2 164 Flags: bus master, fast devsel, latency 0 165 Memory at fc000000 (32-bit, prefetchable) [size=32M] 166 Capabilities: [e4] #09 [2106] 167 Capabilities: [a0] AGP version 3.0 168 169Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043 170(Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic 171names for the bridge ID and the subvendor ID in include/linux/pci_ids.h, 172and then add a case for your subdevice ID at the right place in 173drivers/pci/quirks.c. Then please give it very good testing, to make sure 174that the unhidden SMBus doesn't conflict with e.g. ACPI. 175 176If it works, proves useful (i.e. there are usable chips on the SMBus) 177and seems safe, please submit a patch for inclusion into the kernel. 178 179Note: There's a useful script in lm_sensors 2.10.2 and later, named 180unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to 181temporarily unhide the SMBus without having to patch and recompile your 182kernel. It's very convenient if you just want to check if there's 183anything interesting on your hidden ICH SMBus. 184 185 186---------------------------------------------------------------------------- 187 188The lm_sensors project gratefully acknowledges the support of Texas 189Instruments in the initial development of this driver. 190 191The lm_sensors project gratefully acknowledges the support of Intel in the 192development of SMBus 2.0 / ICH4 features of this driver. 193