| Kernel driver i2c-piix4 |
| |
| Supported adapters: |
| * Intel 82371AB PIIX4 and PIIX4E |
| * Intel 82443MX (440MX) |
| Datasheet: Publicly available at the Intel website |
| * ServerWorks OSB4, CSB5 and CSB6 southbridges |
| Datasheet: Only available via NDA from ServerWorks |
| * Standard Microsystems (SMSC) SLC90E66 (Victory66) southbridge |
| Datasheet: Publicly available at the SMSC website http://www.smsc.com |
| |
| Authors: |
| Frodo Looijaard <frodol@dds.nl> |
| Philip Edelbrock <phil@netroedge.com> |
| |
| |
| Module Parameters |
| ----------------- |
| |
| * force: int |
| Forcibly enable the PIIX4. DANGEROUS! |
| * force_addr: int |
| Forcibly enable the PIIX4 at the given address. EXTREMELY DANGEROUS! |
| * fix_hstcfg: int |
| Fix config register. Needed on some boards (Force CPCI735). |
| |
| |
| Description |
| ----------- |
| |
| The PIIX4 (properly known as the 82371AB) is an Intel chip with a lot of |
| functionality. Among other things, it implements the PCI bus. One of its |
| minor functions is implementing a System Management Bus. This is a true |
| SMBus - you can not access it on I2C levels. The good news is that it |
| natively understands SMBus commands and you do not have to worry about |
| timing problems. The bad news is that non-SMBus devices connected to it can |
| confuse it mightily. Yes, this is known to happen... |
| |
| Do 'lspci -v' and see whether it contains an entry like this: |
| |
| 0000:00:02.3 Bridge: Intel Corp. 82371AB/EB/MB PIIX4 ACPI (rev 02) |
| Flags: medium devsel, IRQ 9 |
| |
| Bus and device numbers may differ, but the function number must be |
| identical (like many PCI devices, the PIIX4 incorporates a number of |
| different 'functions', which can be considered as separate devices). If you |
| find such an entry, you have a PIIX4 SMBus controller. |
| |
| On some computers (most notably, some Dells), the SMBus is disabled by |
| default. If you use the insmod parameter 'force=1', the kernel module will |
| try to enable it. THIS IS VERY DANGEROUS! If the BIOS did not set up a |
| correct address for this module, you could get in big trouble (read: |
| crashes, data corruption, etc.). Try this only as a last resort (try BIOS |
| updates first, for example), and backup first! An even more dangerous |
| option is 'force_addr=<IOPORT>'. This will not only enable the PIIX4 like |
| 'force' foes, but it will also set a new base I/O port address. The SMBus |
| parts of the PIIX4 needs a range of 8 of these addresses to function |
| correctly. If these addresses are already reserved by some other device, |
| you will get into big trouble! DON'T USE THIS IF YOU ARE NOT VERY SURE |
| ABOUT WHAT YOU ARE DOING! |
| |
| The PIIX4E is just an new version of the PIIX4; it is supported as well. |
| The PIIX/PIIX3 does not implement an SMBus or I2C bus, so you can't use |
| this driver on those mainboards. |
| |
| The ServerWorks Southbridges, the Intel 440MX, and the Victory766 are |
| identical to the PIIX4 in I2C/SMBus support. |
| |
| A few OSB4 southbridges are known to be misconfigured by the BIOS. In this |
| case, you have you use the fix_hstcfg module parameter. Do not use it |
| unless you know you have to, because in some cases it also breaks |
| configuration on southbridges that don't need it. |