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 48 Datasheets: Publicly available at the Intel website 49 50On Intel Patsburg and later chipsets, both the normal host SMBus controller 51and the additional 'Integrated Device Function' controllers are supported. 52 53Authors: 54 - Mark Studebaker <mdsxyz123@yahoo.com> 55 - Jean Delvare <jdelvare@suse.de> 56 57 58Module Parameters 59----------------- 60 61* disable_features (bit vector) 62 63Disable selected features normally supported by the device. This makes it 64possible to work around possible driver or hardware bugs if the feature in 65question doesn't work as intended for whatever reason. Bit values: 66 67 ==== ========================================= 68 0x01 disable SMBus PEC 69 0x02 disable the block buffer 70 0x08 disable the I2C block read functionality 71 0x10 don't use interrupts 72 0x20 disable SMBus Host Notify 73 ==== ========================================= 74 75 76Description 77----------- 78 79The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA), 80ICH3 (82801CA/CAM) and later devices (PCH) are Intel chips that are a part of 81Intel's '810' chipset for Celeron-based PCs, '810E' chipset for 82Pentium-based PCs, '815E' chipset, and others. 83 84The ICH chips contain at least SEVEN separate PCI functions in TWO logical 85PCI devices. An output of lspci will show something similar to the 86following:: 87 88 00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01) 89 00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01) 90 00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01) 91 00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01) 92 00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01) 93 94The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial 95Controller. 96 97The ICH chips are quite similar to Intel's PIIX4 chip, at least in the 98SMBus controller. 99 100 101Process Call Support 102-------------------- 103 104Block process call is supported on the 82801EB (ICH5) and later chips. 105 106 107I2C Block Read Support 108---------------------- 109 110I2C block read is supported on the 82801EB (ICH5) and later chips. 111 112 113SMBus 2.0 Support 114----------------- 115 116The 82801DB (ICH4) and later chips support several SMBus 2.0 features. 117 118 119Interrupt Support 120----------------- 121 122PCI interrupt support is supported on the 82801EB (ICH5) and later chips. 123 124 125Hidden ICH SMBus 126---------------- 127 128If your system has an Intel ICH south bridge, but you do NOT see the 129SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the 130BIOS to enable it, it means it has been hidden by the BIOS code. Asus is 131well known for first doing this on their P4B motherboard, and many other 132boards after that. Some vendor machines are affected as well. 133 134The first thing to try is the "i2c-scmi" ACPI driver. It could be that the 135SMBus was hidden on purpose because it'll be driven by ACPI. If the 136i2c-scmi driver works for you, just forget about the i2c-i801 driver and 137don't try to unhide the ICH SMBus. Even if i2c-scmi doesn't work, you 138better make sure that the SMBus isn't used by the ACPI code. Try loading 139the "fan" and "thermal" drivers, and check in /sys/class/thermal. If you 140find a thermal zone with type "acpitz", it's likely that the ACPI is 141accessing the SMBus and it's safer not to unhide it. Only once you are 142certain that ACPI isn't using the SMBus, you can attempt to unhide it. 143 144In order to unhide the SMBus, we need to change the value of a PCI 145register before the kernel enumerates the PCI devices. This is done in 146drivers/pci/quirks.c, where all affected boards must be listed (see 147function asus_hides_smbus_hostbridge.) If the SMBus device is missing, 148and you think there's something interesting on the SMBus (e.g. a 149hardware monitoring chip), you need to add your board to the list. 150 151The motherboard is identified using the subvendor and subdevice IDs of the 152host bridge PCI device. Get yours with ``lspci -n -v -s 00:00.0``:: 153 154 00:00.0 Class 0600: 8086:2570 (rev 02) 155 Subsystem: 1043:80f2 156 Flags: bus master, fast devsel, latency 0 157 Memory at fc000000 (32-bit, prefetchable) [size=32M] 158 Capabilities: [e4] #09 [2106] 159 Capabilities: [a0] AGP version 3.0 160 161Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043 162(Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic 163names for the bridge ID and the subvendor ID in include/linux/pci_ids.h, 164and then add a case for your subdevice ID at the right place in 165drivers/pci/quirks.c. Then please give it very good testing, to make sure 166that the unhidden SMBus doesn't conflict with e.g. ACPI. 167 168If it works, proves useful (i.e. there are usable chips on the SMBus) 169and seems safe, please submit a patch for inclusion into the kernel. 170 171Note: There's a useful script in lm_sensors 2.10.2 and later, named 172unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to 173temporarily unhide the SMBus without having to patch and recompile your 174kernel. It's very convenient if you just want to check if there's 175anything interesting on your hidden ICH SMBus. 176 177 178---------------------------------------------------------------------------- 179 180The lm_sensors project gratefully acknowledges the support of Texas 181Instruments in the initial development of this driver. 182 183The lm_sensors project gratefully acknowledges the support of Intel in the 184development of SMBus 2.0 / ICH4 features of this driver. 185