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 Lynx Point-LP (PCH) 25 * Intel Avoton (SOC) 26 * Intel Wellsburg (PCH) 27 * Intel Coleto Creek (PCH) 28 * Intel Wildcat Point (PCH) 29 * Intel Wildcat Point-LP (PCH) 30 * Intel BayTrail (SOC) 31 * Intel Sunrise Point-H (PCH) 32 * Intel Sunrise Point-LP (PCH) 33 * Intel DNV (SOC) 34 * Intel Broxton (SOC) 35 * Intel Lewisburg (PCH) 36 Datasheets: Publicly available at the Intel website 37 38On Intel Patsburg and later chipsets, both the normal host SMBus controller 39and the additional 'Integrated Device Function' controllers are supported. 40 41Authors: 42 Mark Studebaker <mdsxyz123@yahoo.com> 43 Jean Delvare <jdelvare@suse.de> 44 45 46Module Parameters 47----------------- 48 49* disable_features (bit vector) 50Disable selected features normally supported by the device. This makes it 51possible to work around possible driver or hardware bugs if the feature in 52question doesn't work as intended for whatever reason. Bit values: 53 0x01 disable SMBus PEC 54 0x02 disable the block buffer 55 0x08 disable the I2C block read functionality 56 0x10 don't use interrupts 57 58 59Description 60----------- 61 62The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA), 63ICH3 (82801CA/CAM) and later devices (PCH) are Intel chips that are a part of 64Intel's '810' chipset for Celeron-based PCs, '810E' chipset for 65Pentium-based PCs, '815E' chipset, and others. 66 67The ICH chips contain at least SEVEN separate PCI functions in TWO logical 68PCI devices. An output of lspci will show something similar to the 69following: 70 71 00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01) 72 00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01) 73 00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01) 74 00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01) 75 00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01) 76 77The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial 78Controller. 79 80The ICH chips are quite similar to Intel's PIIX4 chip, at least in the 81SMBus controller. 82 83 84Process Call Support 85-------------------- 86 87Not supported. 88 89 90I2C Block Read Support 91---------------------- 92 93I2C block read is supported on the 82801EB (ICH5) and later chips. 94 95 96SMBus 2.0 Support 97----------------- 98 99The 82801DB (ICH4) and later chips support several SMBus 2.0 features. 100 101 102Interrupt Support 103----------------- 104 105PCI interrupt support is supported on the 82801EB (ICH5) and later chips. 106 107 108Hidden ICH SMBus 109---------------- 110 111If your system has an Intel ICH south bridge, but you do NOT see the 112SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the 113BIOS to enable it, it means it has been hidden by the BIOS code. Asus is 114well known for first doing this on their P4B motherboard, and many other 115boards after that. Some vendor machines are affected as well. 116 117The first thing to try is the "i2c_ec" ACPI driver. It could be that the 118SMBus was hidden on purpose because it'll be driven by ACPI. If the 119i2c_ec driver works for you, just forget about the i2c-i801 driver and 120don't try to unhide the ICH SMBus. Even if i2c_ec doesn't work, you 121better make sure that the SMBus isn't used by the ACPI code. Try loading 122the "fan" and "thermal" drivers, and check in /proc/acpi/fan and 123/proc/acpi/thermal_zone. If you find anything there, it's likely that 124the ACPI is accessing the SMBus and it's safer not to unhide it. Only 125once you are certain that ACPI isn't using the SMBus, you can attempt 126to unhide it. 127 128In order to unhide the SMBus, we need to change the value of a PCI 129register before the kernel enumerates the PCI devices. This is done in 130drivers/pci/quirks.c, where all affected boards must be listed (see 131function asus_hides_smbus_hostbridge.) If the SMBus device is missing, 132and you think there's something interesting on the SMBus (e.g. a 133hardware monitoring chip), you need to add your board to the list. 134 135The motherboard is identified using the subvendor and subdevice IDs of the 136host bridge PCI device. Get yours with "lspci -n -v -s 00:00.0": 137 13800:00.0 Class 0600: 8086:2570 (rev 02) 139 Subsystem: 1043:80f2 140 Flags: bus master, fast devsel, latency 0 141 Memory at fc000000 (32-bit, prefetchable) [size=32M] 142 Capabilities: [e4] #09 [2106] 143 Capabilities: [a0] AGP version 3.0 144 145Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043 146(Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic 147names for the bridge ID and the subvendor ID in include/linux/pci_ids.h, 148and then add a case for your subdevice ID at the right place in 149drivers/pci/quirks.c. Then please give it very good testing, to make sure 150that the unhidden SMBus doesn't conflict with e.g. ACPI. 151 152If it works, proves useful (i.e. there are usable chips on the SMBus) 153and seems safe, please submit a patch for inclusion into the kernel. 154 155Note: There's a useful script in lm_sensors 2.10.2 and later, named 156unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to 157temporarily unhide the SMBus without having to patch and recompile your 158kernel. It's very convenient if you just want to check if there's 159anything interesting on your hidden ICH SMBus. 160 161 162********************** 163The lm_sensors project gratefully acknowledges the support of Texas 164Instruments in the initial development of this driver. 165 166The lm_sensors project gratefully acknowledges the support of Intel in the 167development of SMBus 2.0 / ICH4 features of this driver. 168