projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 LT |
1 | Kernel driver i2c-piix4 |
| 2 | ||
| 3 | Supported adapters: | |
| 4 | * Intel 82371AB PIIX4 and PIIX4E | |
| 5 | * Intel 82443MX (440MX) | |
| 6 | Datasheet: Publicly available at the Intel website | |
| 5f7ea3c5 | 7 | * ServerWorks OSB4, CSB5, CSB6 and HT-1000 southbridges |
| 1da177e4 | 8 | Datasheet: Only available via NDA from ServerWorks |
| 60693e5a | 9 | * ATI IXP200, IXP300, IXP400, SB600, SB700 and SB800 southbridges |
| 02e0c5d5 | 10 | Datasheet: Not publicly available |
| 1da177e4 LT |
11 | * Standard Microsystems (SMSC) SLC90E66 (Victory66) southbridge |
| 12 | Datasheet: Publicly available at the SMSC website http://www.smsc.com | |
| 13 | ||
| 14 | Authors: | |
| 15 | Frodo Looijaard <frodol@dds.nl> | |
| 16 | Philip Edelbrock <phil@netroedge.com> | |
| 17 | ||
| 18 | ||
| 19 | Module Parameters | |
| 20 | ----------------- | |
| 21 | ||
| 22 | * force: int | |
| 23 | Forcibly enable the PIIX4. DANGEROUS! | |
| 24 | * force_addr: int | |
| 25 | Forcibly enable the PIIX4 at the given address. EXTREMELY DANGEROUS! | |
| 1da177e4 LT |
26 | |
| 27 | ||
| 28 | Description | |
| 29 | ----------- | |
| 30 | ||
| 31 | The PIIX4 (properly known as the 82371AB) is an Intel chip with a lot of | |
| 32 | functionality. Among other things, it implements the PCI bus. One of its | |
| 33 | minor functions is implementing a System Management Bus. This is a true | |
| 34 | SMBus - you can not access it on I2C levels. The good news is that it | |
| 35 | natively understands SMBus commands and you do not have to worry about | |
| 36 | timing problems. The bad news is that non-SMBus devices connected to it can | |
| 37 | confuse it mightily. Yes, this is known to happen... | |
| 38 | ||
| 39 | Do 'lspci -v' and see whether it contains an entry like this: | |
| 40 | ||
| 41 | 0000:00:02.3 Bridge: Intel Corp. 82371AB/EB/MB PIIX4 ACPI (rev 02) | |
| 42 | Flags: medium devsel, IRQ 9 | |
| 43 | ||
| 44 | Bus and device numbers may differ, but the function number must be | |
| 45 | identical (like many PCI devices, the PIIX4 incorporates a number of | |
| 46 | different 'functions', which can be considered as separate devices). If you | |
| 47 | find such an entry, you have a PIIX4 SMBus controller. | |
| 48 | ||
| 49 | On some computers (most notably, some Dells), the SMBus is disabled by | |
| 50 | default. If you use the insmod parameter 'force=1', the kernel module will | |
| 51 | try to enable it. THIS IS VERY DANGEROUS! If the BIOS did not set up a | |
| 52 | correct address for this module, you could get in big trouble (read: | |
| 53 | crashes, data corruption, etc.). Try this only as a last resort (try BIOS | |
| 54 | updates first, for example), and backup first! An even more dangerous | |
| 55 | option is 'force_addr=<IOPORT>'. This will not only enable the PIIX4 like | |
| 56 | 'force' foes, but it will also set a new base I/O port address. The SMBus | |
| 57 | parts of the PIIX4 needs a range of 8 of these addresses to function | |
| 58 | correctly. If these addresses are already reserved by some other device, | |
| 59 | you will get into big trouble! DON'T USE THIS IF YOU ARE NOT VERY SURE | |
| 60 | ABOUT WHAT YOU ARE DOING! | |
| 61 | ||
| 62 | The PIIX4E is just an new version of the PIIX4; it is supported as well. | |
| 63 | The PIIX/PIIX3 does not implement an SMBus or I2C bus, so you can't use | |
| 64 | this driver on those mainboards. | |
| 65 | ||
| 7aadb8f9 | 66 | The ServerWorks Southbridges, the Intel 440MX, and the Victory66 are |
| 1da177e4 LT |
67 | identical to the PIIX4 in I2C/SMBus support. |
| 68 | ||
| 54aaa1ca RM |
69 | If you own Force CPCI735 motherboard or other OSB4 based systems you may need |
| 70 | to change the SMBus Interrupt Select register so the SMBus controller uses | |
| 71 | the SMI mode. | |
| 72 | ||
| 73 | 1) Use lspci command and locate the PCI device with the SMBus controller: | |
| 74 | 00:0f.0 ISA bridge: ServerWorks OSB4 South Bridge (rev 4f) | |
| 75 | The line may vary for different chipsets. Please consult the driver source | |
| 76 | for all possible PCI ids (and lspci -n to match them). Lets assume the | |
| 77 | device is located at 00:0f.0. | |
| 78 | 2) Now you just need to change the value in 0xD2 register. Get it first with | |
| 79 | command: lspci -xxx -s 00:0f.0 | |
| 80 | If the value is 0x3 then you need to change it to 0x1 | |
| 81 | setpci -s 00:0f.0 d2.b=1 | |
| 82 | ||
| 83 | Please note that you don't need to do that in all cases, just when the SMBus is | |
| 84 | not working properly. | |
| f9ba6c04 JD |
85 | |
| 86 | ||
| 87 | Hardware-specific issues | |
| 88 | ------------------------ | |
| 89 | ||
| 90 | This driver will refuse to load on IBM systems with an Intel PIIX4 SMBus. | |
| 91 | Some of these machines have an RFID EEPROM (24RF08) connected to the SMBus, | |
| 92 | which can easily get corrupted due to a state machine bug. These are mostly | |
| 93 | Thinkpad laptops, but desktop systems may also be affected. We have no list | |
| 94 | of all affected systems, so the only safe solution was to prevent access to | |
| 95 | the SMBus on all IBM systems (detected using DMI data.) | |
| 96 | ||
| 97 | For additional information, read: | |
| ec1d86c4 | 98 | http://www.lm-sensors.org/browser/lm-sensors/trunk/README.thinkpad |