1======================= 2Kernel driver i2c-piix4 3======================= 4 5Supported adapters: 6 * Intel 82371AB PIIX4 and PIIX4E 7 * Intel 82443MX (440MX) 8 Datasheet: Publicly available at the Intel website 9 * ServerWorks OSB4, CSB5, CSB6, HT-1000 and HT-1100 southbridges 10 Datasheet: Only available via NDA from ServerWorks 11 * ATI IXP200, IXP300, IXP400, SB600, SB700 and SB800 southbridges 12 Datasheet: Not publicly available 13 SB700 register reference available at: 14 http://support.amd.com/us/Embedded_TechDocs/43009_sb7xx_rrg_pub_1.00.pdf 15 * AMD SP5100 (SB700 derivative found on some server mainboards) 16 Datasheet: Publicly available at the AMD website 17 http://support.amd.com/us/Embedded_TechDocs/44413.pdf 18 * AMD Hudson-2, ML, CZ 19 Datasheet: Not publicly available 20 * Hygon CZ 21 Datasheet: Not publicly available 22 * Standard Microsystems (SMSC) SLC90E66 (Victory66) southbridge 23 Datasheet: Publicly available at the SMSC website http://www.smsc.com 24 25Authors: 26 - Frodo Looijaard <frodol@dds.nl> 27 - Philip Edelbrock <phil@netroedge.com> 28 29 30Module Parameters 31----------------- 32 33* force: int 34 Forcibly enable the PIIX4. DANGEROUS! 35* force_addr: int 36 Forcibly enable the PIIX4 at the given address. EXTREMELY DANGEROUS! 37 38 39Description 40----------- 41 42The PIIX4 (properly known as the 82371AB) is an Intel chip with a lot of 43functionality. Among other things, it implements the PCI bus. One of its 44minor functions is implementing a System Management Bus. This is a true 45SMBus - you can not access it on I2C levels. The good news is that it 46natively understands SMBus commands and you do not have to worry about 47timing problems. The bad news is that non-SMBus devices connected to it can 48confuse it mightily. Yes, this is known to happen... 49 50Do ``lspci -v`` and see whether it contains an entry like this:: 51 52 0000:00:02.3 Bridge: Intel Corp. 82371AB/EB/MB PIIX4 ACPI (rev 02) 53 Flags: medium devsel, IRQ 9 54 55Bus and device numbers may differ, but the function number must be 56identical (like many PCI devices, the PIIX4 incorporates a number of 57different 'functions', which can be considered as separate devices). If you 58find such an entry, you have a PIIX4 SMBus controller. 59 60On some computers (most notably, some Dells), the SMBus is disabled by 61default. If you use the insmod parameter 'force=1', the kernel module will 62try to enable it. THIS IS VERY DANGEROUS! If the BIOS did not set up a 63correct address for this module, you could get in big trouble (read: 64crashes, data corruption, etc.). Try this only as a last resort (try BIOS 65updates first, for example), and backup first! An even more dangerous 66option is 'force_addr=<IOPORT>'. This will not only enable the PIIX4 like 67'force' does, but it will also set a new base I/O port address. The SMBus 68parts of the PIIX4 needs a range of 8 of these addresses to function 69correctly. If these addresses are already reserved by some other device, 70you will get into big trouble! DON'T USE THIS IF YOU ARE NOT VERY SURE 71ABOUT WHAT YOU ARE DOING! 72 73The PIIX4E is just an new version of the PIIX4; it is supported as well. 74The PIIX/PIIX3 does not implement an SMBus or I2C bus, so you can't use 75this driver on those mainboards. 76 77The ServerWorks Southbridges, the Intel 440MX, and the Victory66 are 78identical to the PIIX4 in I2C/SMBus support. 79 80The AMD SB700, SB800, SP5100 and Hudson-2 chipsets implement two 81PIIX4-compatible SMBus controllers. If your BIOS initializes the 82secondary controller, it will be detected by this driver as 83an "Auxiliary SMBus Host Controller". 84 85If you own Force CPCI735 motherboard or other OSB4 based systems you may need 86to change the SMBus Interrupt Select register so the SMBus controller uses 87the SMI mode. 88 891) Use ``lspci`` command and locate the PCI device with the SMBus controller: 90 00:0f.0 ISA bridge: ServerWorks OSB4 South Bridge (rev 4f) 91 The line may vary for different chipsets. Please consult the driver source 92 for all possible PCI ids (and ``lspci -n`` to match them). Let's assume the 93 device is located at 00:0f.0. 942) Now you just need to change the value in 0xD2 register. Get it first with 95 command: ``lspci -xxx -s 00:0f.0`` 96 If the value is 0x3 then you need to change it to 0x1: 97 ``setpci -s 00:0f.0 d2.b=1`` 98 99Please note that you don't need to do that in all cases, just when the SMBus is 100not working properly. 101 102 103Hardware-specific issues 104------------------------ 105 106This driver will refuse to load on IBM systems with an Intel PIIX4 SMBus. 107Some of these machines have an RFID EEPROM (24RF08) connected to the SMBus, 108which can easily get corrupted due to a state machine bug. These are mostly 109Thinkpad laptops, but desktop systems may also be affected. We have no list 110of all affected systems, so the only safe solution was to prevent access to 111the SMBus on all IBM systems (detected using DMI data.) 112