2005-04-16 18:20:36 -04:00
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Kernel driver i2c-piix4
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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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2006-02-27 17:11:45 -05:00
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* ServerWorks OSB4, CSB5, CSB6 and HT-1000 southbridges
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2005-04-16 18:20:36 -04:00
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Datasheet: Only available via NDA from ServerWorks
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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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Authors:
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Frodo Looijaard <frodol@dds.nl>
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Philip Edelbrock <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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* fix_hstcfg: int
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Fix config register. Needed on some boards (Force CPCI735).
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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 can
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confuse it mightily. Yes, this is known to happen...
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Do 'lspci -v' and see whether it contains an entry like this:
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0000:00:02.3 Bridge: Intel Corp. 82371AB/EB/MB PIIX4 ACPI (rev 02)
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Flags: medium devsel, IRQ 9
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Bus and device numbers may differ, but the function number must be
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identical (like many PCI devices, the PIIX4 incorporates a number of
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different 'functions', which can be considered as separate devices). If you
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find such 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 will
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try to enable it. THIS IS VERY DANGEROUS! If the BIOS did not set up a
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correct address for this module, you could get in big trouble (read:
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crashes, data corruption, etc.). Try this only as a last resort (try BIOS
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updates first, for example), and backup first! An even more dangerous
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option is 'force_addr=<IOPORT>'. This will not only enable the PIIX4 like
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'force' foes, but it will also set a new base I/O port address. The SMBus
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parts of the PIIX4 needs a range of 8 of these addresses to function
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correctly. If these addresses are already reserved by some other device,
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you will get into big trouble! DON'T USE THIS IF YOU ARE NOT VERY SURE
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ABOUT WHAT YOU ARE DOING!
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The PIIX4E is just an new version of the PIIX4; it is supported as well.
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The PIIX/PIIX3 does not implement an SMBus or I2C bus, so you can't use
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this driver on those mainboards.
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The ServerWorks Southbridges, the Intel 440MX, and the Victory766 are
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identical to the PIIX4 in I2C/SMBus support.
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A few OSB4 southbridges are known to be misconfigured by the BIOS. In this
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case, you have you use the fix_hstcfg module parameter. Do not use it
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unless you know you have to, because in some cases it also breaks
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configuration on southbridges that don't need it.
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