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