1Kernel driver i2c-piix4 2 3Supported adapters: 4 * Intel 82371AB PIIX4 and PIIX4E 5 * Intel 82443MX (440MX) 6 Datasheet: Publicly available at the Intel website 7 * ServerWorks OSB4, CSB5, CSB6, HT-1000 and HT-1100 southbridges 8 Datasheet: Only available via NDA from ServerWorks 9 * ATI IXP200, IXP300, IXP400, SB600, SB700 and SB800 southbridges 10 Datasheet: Not publicly available 11 * AMD Hudson-2 12 Datasheet: Not publicly available 13 * Standard Microsystems (SMSC) SLC90E66 (Victory66) southbridge 14 Datasheet: Publicly available at the SMSC website http://www.smsc.com 15 16Authors: 17 Frodo Looijaard <frodol@dds.nl> 18 Philip Edelbrock <phil@netroedge.com> 19 20 21Module Parameters 22----------------- 23 24* force: int 25 Forcibly enable the PIIX4. DANGEROUS! 26* force_addr: int 27 Forcibly enable the PIIX4 at the given address. EXTREMELY DANGEROUS! 28 29 30Description 31----------- 32 33The PIIX4 (properly known as the 82371AB) is an Intel chip with a lot of 34functionality. Among other things, it implements the PCI bus. One of its 35minor functions is implementing a System Management Bus. This is a true 36SMBus - you can not access it on I2C levels. The good news is that it 37natively understands SMBus commands and you do not have to worry about 38timing problems. The bad news is that non-SMBus devices connected to it can 39confuse it mightily. Yes, this is known to happen... 40 41Do 'lspci -v' and see whether it contains an entry like this: 42 430000:00:02.3 Bridge: Intel Corp. 82371AB/EB/MB PIIX4 ACPI (rev 02) 44 Flags: medium devsel, IRQ 9 45 46Bus and device numbers may differ, but the function number must be 47identical (like many PCI devices, the PIIX4 incorporates a number of 48different 'functions', which can be considered as separate devices). If you 49find such an entry, you have a PIIX4 SMBus controller. 50 51On some computers (most notably, some Dells), the SMBus is disabled by 52default. If you use the insmod parameter 'force=1', the kernel module will 53try to enable it. THIS IS VERY DANGEROUS! If the BIOS did not set up a 54correct address for this module, you could get in big trouble (read: 55crashes, data corruption, etc.). Try this only as a last resort (try BIOS 56updates first, for example), and backup first! An even more dangerous 57option is 'force_addr=<IOPORT>'. This will not only enable the PIIX4 like 58'force' foes, but it will also set a new base I/O port address. The SMBus 59parts of the PIIX4 needs a range of 8 of these addresses to function 60correctly. If these addresses are already reserved by some other device, 61you will get into big trouble! DON'T USE THIS IF YOU ARE NOT VERY SURE 62ABOUT WHAT YOU ARE DOING! 63 64The PIIX4E is just an new version of the PIIX4; it is supported as well. 65The PIIX/PIIX3 does not implement an SMBus or I2C bus, so you can't use 66this driver on those mainboards. 67 68The ServerWorks Southbridges, the Intel 440MX, and the Victory66 are 69identical to the PIIX4 in I2C/SMBus support. 70 71If you own Force CPCI735 motherboard or other OSB4 based systems you may need 72to change the SMBus Interrupt Select register so the SMBus controller uses 73the SMI mode. 74 751) Use lspci command and locate the PCI device with the SMBus controller: 76 00:0f.0 ISA bridge: ServerWorks OSB4 South Bridge (rev 4f) 77 The line may vary for different chipsets. Please consult the driver source 78 for all possible PCI ids (and lspci -n to match them). Lets assume the 79 device is located at 00:0f.0. 802) Now you just need to change the value in 0xD2 register. Get it first with 81 command: lspci -xxx -s 00:0f.0 82 If the value is 0x3 then you need to change it to 0x1 83 setpci -s 00:0f.0 d2.b=1 84 85Please note that you don't need to do that in all cases, just when the SMBus is 86not working properly. 87 88 89Hardware-specific issues 90------------------------ 91 92This driver will refuse to load on IBM systems with an Intel PIIX4 SMBus. 93Some of these machines have an RFID EEPROM (24RF08) connected to the SMBus, 94which can easily get corrupted due to a state machine bug. These are mostly 95Thinkpad laptops, but desktop systems may also be affected. We have no list 96of all affected systems, so the only safe solution was to prevent access to 97the SMBus on all IBM systems (detected using DMI data.) 98 99For additional information, read: 100http://www.lm-sensors.org/browser/lm-sensors/trunk/README 101