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Kernel driver `i2c-piix4.o' |
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Status: Complete and well-tested |
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except for Victory66 support which is Alpha. |
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Supported adapters: |
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* Intel 82371AB PIIX4 and PIIX4E |
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* Intel 82443MX (440MX) |
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Datasheet: Publicly available at the Intel website |
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* ServerWorks OSB4, CSB5, CSB6 and HT-1000 southbridges |
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Datasheet: Only available via NDA from ServerWorks |
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* ATI IXP200, IXP300, IXP400, SB600, SB700 and SB800 southbridges |
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Datasheet: Not publicly available |
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* Standard Microsystems (SMSC) SLC90E66 (Victory66) southbridge |
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Datasheet: Publicly available at the SMSC website http://www.smsc.com |
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Author: Frodo Looijaard <frodol@dds.nl> and Philip Edelbrock |
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<phil@netroedge.com> |
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Module Parameters |
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----------------- |
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* force: int |
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Forcibly enable the PIIX4. DANGEROUS! |
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* force_addr: int |
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Forcibly enable the PIIX4 at the given address. EXTREMELY DANGEROUS! |
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Description |
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----------- |
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The PIIX4 (properly known as the 82371AB) is an Intel chip with a lot of |
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functionality. Among other things, it implements the PCI bus. One of its |
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minor functions is implementing a System Management Bus. This is a true |
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SMBus - you can not access it on I2C levels. The good news is that it |
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natively understands SMBus commands and you do not have to worry about |
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timing problems. The bad news is that non-SMBus devices connected to it |
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can confuse it mightily. Yes, this is known to happen... |
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Cat /proc/pci, and see whether it contains an entry like this: |
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Bus 0, device 1, function 3: |
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Bridge: Intel 82371AB PIIX4 ACPI (rev 1). |
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Medium devsel. Fast back-to-back capable. |
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Bus and device numbers may differ, but the function number must be identical |
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(like many PCI devices, the PIIX4 incorporates a number of different |
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'functions', which can be considered as separate devices). If you find such |
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an entry, you have a PIIX4 SMBus controller. |
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On some computers (most notably, some Dells), the SMBus is disabled by |
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default. If you use the insmod parameter 'force=1', the kernel module |
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will try to enable it. THIS IS VERY DANGEROUS! If the BIOS did not |
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set up a correct address for this module, you could get in big trouble |
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(read: crashes, data corruption, etc.). Try this only as a last resort |
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(try BIOS updates first, for example), and backup first! An even more |
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dangerous option is 'force_addr=<IOPORT>'. This will not only enable the |
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PIIX4 like 'force' foes, but it will also set a new base I/O port address. |
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The SMBus parts of the PIIX4 needs a range of 8 of these addresses to |
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function correctly. If these addresses are already reserved by some other |
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device, you will get into big trouble! DON'T USE THIS IF YOU ARE NOT VERY |
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SURE ABOUT WHAT YOU ARE DOING! |
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The PIIX4E is just an new version of the PIIX4; it is supported as well. The |
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PIIX/PIIX3 does not implement an SMBus or I2C bus, so you can't use this |
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driver on those mainboards. |
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The ServerWorks Southbridges, the Intel 440MX, |
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and the Victory66 are identical to the PIIX4 in I2C/SMBus support. |
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If you own Force CPCI735 motherboard or other OSB4 based systems you may need |
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to change the SMBus Interrupt Select register so the SMBus controller uses |
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the SMI mode. |
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1) Use lspci command and locate the PCI device with the SMBus controller: |
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00:0f.0 ISA bridge: ServerWorks OSB4 South Bridge (rev 4f) |
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The line may vary for different chipsets. Please consult the driver source |
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for all possible PCI ids (and lspci -n to match them). Lets assume the |
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device is located at 00:0f.0. |
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2) Now you just need to change the value in 0xD2 register. Get it first with |
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command: lspci -xxx -s 00:0f.0 |
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If the value is 0x3 then you need to change it to 0x1 |
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setpci -s 00:0f.0 d2.b=1 |
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Please note that you don't need to do that in all cases, just when the SMBus is |
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not working properly. |
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Hardware-specific issues |
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------------------------ |
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This driver will refuse to load on IBM systems with an Intel PIIX4 SMBus. |
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Some of these machines have an RFID EEPROM (24RF08) connected to the SMBus, |
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which can easily get corrupted due to a state machine bug. These are mostly |
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Thinkpad laptops, but desktop systems may also be affected. We have no list |
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of all affected systems, so the only safe solution was to prevent access to |
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the SMBus on all IBM systems (detected using DMI data.) |
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For additional information, read README.thinkpad. |
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