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 Datasheets: Publicly available at the Intel website 34 35On Intel Patsburg and later chipsets, both the normal host SMBus controller 36and the additional 'Integrated Device Function' controllers are supported. 37 38Authors: 39 Mark Studebaker <mdsxyz123@yahoo.com> 40 Jean Delvare <jdelvare@suse.de> 41 42 43Module Parameters 44----------------- 45 46* disable_features (bit vector) 47Disable selected features normally supported by the device. This makes it 48possible to work around possible driver or hardware bugs if the feature in 49question doesn't work as intended for whatever reason. Bit values: 50 0x01 disable SMBus PEC 51 0x02 disable the block buffer 52 0x08 disable the I2C block read functionality 53 0x10 don't use interrupts 54 55 56Description 57----------- 58 59The ICH (properly known as the 82801AA), ICH0 (82801AB), ICH2 (82801BA), 60ICH3 (82801CA/CAM) and later devices (PCH) are Intel chips that are a part of 61Intel's '810' chipset for Celeron-based PCs, '810E' chipset for 62Pentium-based PCs, '815E' chipset, and others. 63 64The ICH chips contain at least SEVEN separate PCI functions in TWO logical 65PCI devices. An output of lspci will show something similar to the 66following: 67 68 00:1e.0 PCI bridge: Intel Corporation: Unknown device 2418 (rev 01) 69 00:1f.0 ISA bridge: Intel Corporation: Unknown device 2410 (rev 01) 70 00:1f.1 IDE interface: Intel Corporation: Unknown device 2411 (rev 01) 71 00:1f.2 USB Controller: Intel Corporation: Unknown device 2412 (rev 01) 72 00:1f.3 Unknown class [0c05]: Intel Corporation: Unknown device 2413 (rev 01) 73 74The SMBus controller is function 3 in device 1f. Class 0c05 is SMBus Serial 75Controller. 76 77The ICH chips are quite similar to Intel's PIIX4 chip, at least in the 78SMBus controller. 79 80 81Process Call Support 82-------------------- 83 84Not supported. 85 86 87I2C Block Read Support 88---------------------- 89 90I2C block read is supported on the 82801EB (ICH5) and later chips. 91 92 93SMBus 2.0 Support 94----------------- 95 96The 82801DB (ICH4) and later chips support several SMBus 2.0 features. 97 98 99Interrupt Support 100----------------- 101 102PCI interrupt support is supported on the 82801EB (ICH5) and later chips. 103 104 105Hidden ICH SMBus 106---------------- 107 108If your system has an Intel ICH south bridge, but you do NOT see the 109SMBus device at 00:1f.3 in lspci, and you can't figure out any way in the 110BIOS to enable it, it means it has been hidden by the BIOS code. Asus is 111well known for first doing this on their P4B motherboard, and many other 112boards after that. Some vendor machines are affected as well. 113 114The first thing to try is the "i2c_ec" ACPI driver. It could be that the 115SMBus was hidden on purpose because it'll be driven by ACPI. If the 116i2c_ec driver works for you, just forget about the i2c-i801 driver and 117don't try to unhide the ICH SMBus. Even if i2c_ec doesn't work, you 118better make sure that the SMBus isn't used by the ACPI code. Try loading 119the "fan" and "thermal" drivers, and check in /proc/acpi/fan and 120/proc/acpi/thermal_zone. If you find anything there, it's likely that 121the ACPI is accessing the SMBus and it's safer not to unhide it. Only 122once you are certain that ACPI isn't using the SMBus, you can attempt 123to unhide it. 124 125In order to unhide the SMBus, we need to change the value of a PCI 126register before the kernel enumerates the PCI devices. This is done in 127drivers/pci/quirks.c, where all affected boards must be listed (see 128function asus_hides_smbus_hostbridge.) If the SMBus device is missing, 129and you think there's something interesting on the SMBus (e.g. a 130hardware monitoring chip), you need to add your board to the list. 131 132The motherboard is identified using the subvendor and subdevice IDs of the 133host bridge PCI device. Get yours with "lspci -n -v -s 00:00.0": 134 13500:00.0 Class 0600: 8086:2570 (rev 02) 136 Subsystem: 1043:80f2 137 Flags: bus master, fast devsel, latency 0 138 Memory at fc000000 (32-bit, prefetchable) [size=32M] 139 Capabilities: [e4] #09 [2106] 140 Capabilities: [a0] AGP version 3.0 141 142Here the host bridge ID is 2570 (82865G/PE/P), the subvendor ID is 1043 143(Asus) and the subdevice ID is 80f2 (P4P800-X). You can find the symbolic 144names for the bridge ID and the subvendor ID in include/linux/pci_ids.h, 145and then add a case for your subdevice ID at the right place in 146drivers/pci/quirks.c. Then please give it very good testing, to make sure 147that the unhidden SMBus doesn't conflict with e.g. ACPI. 148 149If it works, proves useful (i.e. there are usable chips on the SMBus) 150and seems safe, please submit a patch for inclusion into the kernel. 151 152Note: There's a useful script in lm_sensors 2.10.2 and later, named 153unhide_ICH_SMBus (in prog/hotplug), which uses the fakephp driver to 154temporarily unhide the SMBus without having to patch and recompile your 155kernel. It's very convenient if you just want to check if there's 156anything interesting on your hidden ICH SMBus. 157 158 159********************** 160The lm_sensors project gratefully acknowledges the support of Texas 161Instruments in the initial development of this driver. 162 163The lm_sensors project gratefully acknowledges the support of Intel in the 164development of SMBus 2.0 / ICH4 features of this driver. 165