| Kernel driver i2c-piix4 |
| |
| Supported adapters: |
| * Intel 82371AB PIIX4 and PIIX4E |
| * Intel 82443MX (440MX) |
| Datasheet: Publicly available at the Intel website |
| * ServerWorks OSB4, CSB5, CSB6, HT-1000 and HT-1100 southbridges |
| Datasheet: Only available via NDA from ServerWorks |
| * ATI IXP200, IXP300, IXP400, SB600, SB700 and SB800 southbridges |
| Datasheet: Not publicly available |
| * AMD SB900 |
| Datasheet: Not publicly available |
| * 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! |
| |
| |
| 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 Victory66 are |
| identical to the PIIX4 in I2C/SMBus support. |
| |
| If you own Force CPCI735 motherboard or other OSB4 based systems you may need |
| to change the SMBus Interrupt Select register so the SMBus controller uses |
| the SMI mode. |
| |
| 1) Use lspci command and locate the PCI device with the SMBus controller: |
| 00:0f.0 ISA bridge: ServerWorks OSB4 South Bridge (rev 4f) |
| The line may vary for different chipsets. Please consult the driver source |
| for all possible PCI ids (and lspci -n to match them). Lets assume the |
| device is located at 00:0f.0. |
| 2) Now you just need to change the value in 0xD2 register. Get it first with |
| command: lspci -xxx -s 00:0f.0 |
| If the value is 0x3 then you need to change it to 0x1 |
| setpci -s 00:0f.0 d2.b=1 |
| |
| Please note that you don't need to do that in all cases, just when the SMBus is |
| not working properly. |
| |
| |
| Hardware-specific issues |
| ------------------------ |
| |
| This driver will refuse to load on IBM systems with an Intel PIIX4 SMBus. |
| Some of these machines have an RFID EEPROM (24RF08) connected to the SMBus, |
| which can easily get corrupted due to a state machine bug. These are mostly |
| Thinkpad laptops, but desktop systems may also be affected. We have no list |
| of all affected systems, so the only safe solution was to prevent access to |
| the SMBus on all IBM systems (detected using DMI data.) |
| |
| For additional information, read: |
| http://www.lm-sensors.org/browser/lm-sensors/trunk/README.thinkpad |