1Kernel driver i2c-i801 2 3Supported adapters: 4 * Intel 82801AA and 82801AB (ICH and ICH0 - part of the 5 '810' and '810E' chipsets) 6 * Intel 82801BA (ICH2 - part of the '815E' chipset) 7 * Intel 82801CA/CAM (ICH3) 8 * Intel 82801DB (ICH4) (HW PEC supported) 9 * Intel 82801EB/ER (ICH5) (HW PEC supported) 10 * Intel 6300ESB 11 * Intel 82801FB/FR/FW/FRW (ICH6) 12 * Intel 82801G (ICH7) 13 * Intel 631xESB/632xESB (ESB2) 14 * Intel 82801H (ICH8) 15 * Intel 82801I (ICH9) 16 * Intel EP80579 (Tolapai) 17 * Intel 82801JI (ICH10) 18 * Intel 5/3400 Series (PCH) 19 * Intel 6 Series (PCH) 20 * Intel Patsburg (PCH) 21 * Intel DH89xxCC (PCH) 22 * Intel Panther Point (PCH) 23 * Intel Lynx Point (PCH) 24 * Intel Avoton (SOC) 25 * Intel Wellsburg (PCH) 26 * Intel Coleto Creek (PCH) 27 * Intel Wildcat Point (PCH) 28 * Intel BayTrail (SOC) 29 * Intel Braswell (SOC) 30 * Intel Sunrise Point (PCH) 31 * Intel Kaby Lake (PCH) 32 * Intel DNV (SOC) 33 * Intel Broxton (SOC) 34 * Intel Lewisburg (PCH) 35 * Intel Gemini Lake (SOC) 36 * Intel Cannon Lake (PCH) 37 * Intel Cedar Fork (PCH) 38 * Intel Ice Lake (PCH) 39 Datasheets: Publicly available at the Intel website 40 41On Intel Patsburg and later chipsets, both the normal host SMBus controller 42and the additional 'Integrated Device Function' controllers are supported. 43 44Authors: 45 Mark Studebaker <mdsxyz123@yahoo.com> 46 Jean Delvare <jdelvare@suse.de> 47 48 49Module Parameters 50----------------- 51 52* disable_features (bit vector) 53Disable selected features normally supported by the device. This makes it 54possible to work around possible driver or hardware bugs if the feature in 55question doesn't work as intended for whatever reason. Bit values: 56 0x01 disable SMBus PEC 57 0x02 disable the block buffer 58 0x08 disable the I2C block read functionality 59 0x10 don't use interrupts 60 61 62Description 63----------- 64 65The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA), 66ICH3 (82801CA/CAM) and later devices (PCH) are Intel chips that are a part of 67Intel's '810' chipset for Celeron-based PCs, '810E' chipset for 68Pentium-based PCs, '815E' chipset, and others. 69 70The ICH chips contain at least SEVEN separate PCI functions in TWO logical 71PCI devices. An output of lspci will show something similar to the 72following: 73 74 00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01) 75 00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01) 76 00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01) 77 00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01) 78 00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01) 79 80The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial 81Controller. 82 83The ICH chips are quite similar to Intel's PIIX4 chip, at least in the 84SMBus controller. 85 86 87Process Call Support 88-------------------- 89 90Not supported. 91 92 93I2C Block Read Support 94---------------------- 95 96I2C block read is supported on the 82801EB (ICH5) and later chips. 97 98 99SMBus 2.0 Support 100----------------- 101 102The 82801DB (ICH4) and later chips support several SMBus 2.0 features. 103 104 105Interrupt Support 106----------------- 107 108PCI interrupt support is supported on the 82801EB (ICH5) and later chips. 109 110 111Hidden ICH SMBus 112---------------- 113 114If your system has an Intel ICH south bridge, but you do NOT see the 115SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the 116BIOS to enable it, it means it has been hidden by the BIOS code. Asus is 117well known for first doing this on their P4B motherboard, and many other 118boards after that. Some vendor machines are affected as well. 119 120The first thing to try is the "i2c_ec" ACPI driver. It could be that the 121SMBus was hidden on purpose because it'll be driven by ACPI. If the 122i2c_ec driver works for you, just forget about the i2c-i801 driver and 123don't try to unhide the ICH SMBus. Even if i2c_ec doesn't work, you 124better make sure that the SMBus isn't used by the ACPI code. Try loading 125the "fan" and "thermal" drivers, and check in /proc/acpi/fan and 126/proc/acpi/thermal_zone. If you find anything there, it's likely that 127the ACPI is accessing the SMBus and it's safer not to unhide it. Only 128once you are certain that ACPI isn't using the SMBus, you can attempt 129to unhide it. 130 131In order to unhide the SMBus, we need to change the value of a PCI 132register before the kernel enumerates the PCI devices. This is done in 133drivers/pci/quirks.c, where all affected boards must be listed (see 134function asus_hides_smbus_hostbridge.) If the SMBus device is missing, 135and you think there's something interesting on the SMBus (e.g. a 136hardware monitoring chip), you need to add your board to the list. 137 138The motherboard is identified using the subvendor and subdevice IDs of the 139host bridge PCI device. Get yours with "lspci -n -v -s 00:00.0": 140 14100:00.0 Class 0600: 8086:2570 (rev 02) 142 Subsystem: 1043:80f2 143 Flags: bus master, fast devsel, latency 0 144 Memory at fc000000 (32-bit, prefetchable) [size=32M] 145 Capabilities: [e4] #09 [2106] 146 Capabilities: [a0] AGP version 3.0 147 148Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043 149(Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic 150names for the bridge ID and the subvendor ID in include/linux/pci_ids.h, 151and then add a case for your subdevice ID at the right place in 152drivers/pci/quirks.c. Then please give it very good testing, to make sure 153that the unhidden SMBus doesn't conflict with e.g. ACPI. 154 155If it works, proves useful (i.e. there are usable chips on the SMBus) 156and seems safe, please submit a patch for inclusion into the kernel. 157 158Note: There's a useful script in lm_sensors 2.10.2 and later, named 159unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to 160temporarily unhide the SMBus without having to patch and recompile your 161kernel. It's very convenient if you just want to check if there's 162anything interesting on your hidden ICH SMBus. 163 164 165********************** 166The lm_sensors project gratefully acknowledges the support of Texas 167Instruments in the initial development of this driver. 168 169The lm_sensors project gratefully acknowledges the support of Intel in the 170development of SMBus 2.0 / ICH4 features of this driver. 171
