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