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 SB700 register reference available at: 12 http://support.amd.com/us/Embedded_TechDocs/43009_sb7xx_rrg_pub_1.00.pdf 13 * AMD SP5100 (SB700 derivative found on some server mainboards) 14 Datasheet: Publicly available at the AMD website 15 http://support.amd.com/us/Embedded_TechDocs/44413.pdf 16 * AMD Hudson-2, ML, CZ 17 Datasheet: Not publicly available 18 * Standard Microsystems (SMSC) SLC90E66 (Victory66) southbridge 19 Datasheet: Publicly available at the SMSC website http://www.smsc.com 20 21Authors: 22 Frodo Looijaard <frodol@dds.nl> 23 Philip Edelbrock <phil@netroedge.com> 24 25 26Module Parameters 27----------------- 28 29* force: int 30 Forcibly enable the PIIX4. DANGEROUS! 31* force_addr: int 32 Forcibly enable the PIIX4 at the given address. EXTREMELY DANGEROUS! 33 34 35Description 36----------- 37 38The PIIX4 (properly known as the 82371AB) is an Intel chip with a lot of 39functionality. Among other things, it implements the PCI bus. One of its 40minor functions is implementing a System Management Bus. This is a true 41SMBus - you can not access it on I2C levels. The good news is that it 42natively understands SMBus commands and you do not have to worry about 43timing problems. The bad news is that non-SMBus devices connected to it can 44confuse it mightily. Yes, this is known to happen... 45 46Do 'lspci -v' and see whether it contains an entry like this: 47 480000:00:02.3 Bridge: Intel Corp. 82371AB/EB/MB PIIX4 ACPI (rev 02) 49 Flags: medium devsel, IRQ 9 50 51Bus and device numbers may differ, but the function number must be 52identical (like many PCI devices, the PIIX4 incorporates a number of 53different 'functions', which can be considered as separate devices). If you 54find such an entry, you have a PIIX4 SMBus controller. 55 56On some computers (most notably, some Dells), the SMBus is disabled by 57default. If you use the insmod parameter 'force=1', the kernel module will 58try to enable it. THIS IS VERY DANGEROUS! If the BIOS did not set up a 59correct address for this module, you could get in big trouble (read: 60crashes, data corruption, etc.). Try this only as a last resort (try BIOS 61updates first, for example), and backup first! An even more dangerous 62option is 'force_addr=<IOPORT>'. This will not only enable the PIIX4 like 63'force' foes, but it will also set a new base I/O port address. The SMBus 64parts of the PIIX4 needs a range of 8 of these addresses to function 65correctly. If these addresses are already reserved by some other device, 66you will get into big trouble! DON'T USE THIS IF YOU ARE NOT VERY SURE 67ABOUT WHAT YOU ARE DOING! 68 69The PIIX4E is just an new version of the PIIX4; it is supported as well. 70The PIIX/PIIX3 does not implement an SMBus or I2C bus, so you can't use 71this driver on those mainboards. 72 73The ServerWorks Southbridges, the Intel 440MX, and the Victory66 are 74identical to the PIIX4 in I2C/SMBus support. 75 76The AMD SB700, SB800, SP5100 and Hudson-2 chipsets implement two 77PIIX4-compatible SMBus controllers. If your BIOS initializes the 78secondary controller, it will be detected by this driver as 79an "Auxiliary SMBus Host Controller". 80 81If you own Force CPCI735 motherboard or other OSB4 based systems you may need 82to change the SMBus Interrupt Select register so the SMBus controller uses 83the SMI mode. 84 851) Use lspci command and locate the PCI device with the SMBus controller: 86 00:0f.0 ISA bridge: ServerWorks OSB4 South Bridge (rev 4f) 87 The line may vary for different chipsets. Please consult the driver source 88 for all possible PCI ids (and lspci -n to match them). Lets assume the 89 device is located at 00:0f.0. 902) Now you just need to change the value in 0xD2 register. Get it first with 91 command: lspci -xxx -s 00:0f.0 92 If the value is 0x3 then you need to change it to 0x1 93 setpci -s 00:0f.0 d2.b=1 94 95Please note that you don't need to do that in all cases, just when the SMBus is 96not working properly. 97 98 99Hardware-specific issues 100------------------------ 101 102This driver will refuse to load on IBM systems with an Intel PIIX4 SMBus. 103Some of these machines have an RFID EEPROM (24RF08) connected to the SMBus, 104which can easily get corrupted due to a state machine bug. These are mostly 105Thinkpad laptops, but desktop systems may also be affected. We have no list 106of all affected systems, so the only safe solution was to prevent access to 107the SMBus on all IBM systems (detected using DMI data.) 108 109For additional information, read: 110http://www.lm-sensors.org/browser/lm-sensors/trunk/README 111
