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