Commit | Line | Data |
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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 | |
506a8b6c | 7 | * ServerWorks OSB4, CSB5, CSB6, HT-1000 and HT-1100 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 |
3806e94b | 11 | * AMD Hudson-2 |
76b3e28f | 12 | Datasheet: Not publicly available |
1da177e4 LT |
13 | * Standard Microsystems (SMSC) SLC90E66 (Victory66) southbridge |
14 | Datasheet: Publicly available at the SMSC website http://www.smsc.com | |
15 | ||
16 | Authors: | |
17 | Frodo Looijaard <frodol@dds.nl> | |
18 | Philip Edelbrock <phil@netroedge.com> | |
19 | ||
20 | ||
21 | Module Parameters | |
22 | ----------------- | |
23 | ||
24 | * force: int | |
25 | Forcibly enable the PIIX4. DANGEROUS! | |
26 | * force_addr: int | |
27 | Forcibly enable the PIIX4 at the given address. EXTREMELY DANGEROUS! | |
1da177e4 LT |
28 | |
29 | ||
30 | Description | |
31 | ----------- | |
32 | ||
33 | The PIIX4 (properly known as the 82371AB) is an Intel chip with a lot of | |
34 | functionality. Among other things, it implements the PCI bus. One of its | |
35 | minor functions is implementing a System Management Bus. This is a true | |
36 | SMBus - you can not access it on I2C levels. The good news is that it | |
37 | natively understands SMBus commands and you do not have to worry about | |
38 | timing problems. The bad news is that non-SMBus devices connected to it can | |
39 | confuse it mightily. Yes, this is known to happen... | |
40 | ||
41 | Do 'lspci -v' and see whether it contains an entry like this: | |
42 | ||
43 | 0000:00:02.3 Bridge: Intel Corp. 82371AB/EB/MB PIIX4 ACPI (rev 02) | |
44 | Flags: medium devsel, IRQ 9 | |
45 | ||
46 | Bus and device numbers may differ, but the function number must be | |
47 | identical (like many PCI devices, the PIIX4 incorporates a number of | |
48 | different 'functions', which can be considered as separate devices). If you | |
49 | find such an entry, you have a PIIX4 SMBus controller. | |
50 | ||
51 | On some computers (most notably, some Dells), the SMBus is disabled by | |
52 | default. If you use the insmod parameter 'force=1', the kernel module will | |
53 | try to enable it. THIS IS VERY DANGEROUS! If the BIOS did not set up a | |
54 | correct address for this module, you could get in big trouble (read: | |
55 | crashes, data corruption, etc.). Try this only as a last resort (try BIOS | |
56 | updates first, for example), and backup first! An even more dangerous | |
57 | option is 'force_addr=<IOPORT>'. This will not only enable the PIIX4 like | |
58 | 'force' foes, but it will also set a new base I/O port address. The SMBus | |
59 | parts of the PIIX4 needs a range of 8 of these addresses to function | |
60 | correctly. If these addresses are already reserved by some other device, | |
61 | you will get into big trouble! DON'T USE THIS IF YOU ARE NOT VERY SURE | |
62 | ABOUT WHAT YOU ARE DOING! | |
63 | ||
64 | The PIIX4E is just an new version of the PIIX4; it is supported as well. | |
65 | The PIIX/PIIX3 does not implement an SMBus or I2C bus, so you can't use | |
66 | this driver on those mainboards. | |
67 | ||
7aadb8f9 | 68 | The ServerWorks Southbridges, the Intel 440MX, and the Victory66 are |
1da177e4 LT |
69 | identical to the PIIX4 in I2C/SMBus support. |
70 | ||
54aaa1ca RM |
71 | If you own Force CPCI735 motherboard or other OSB4 based systems you may need |
72 | to change the SMBus Interrupt Select register so the SMBus controller uses | |
73 | the SMI mode. | |
74 | ||
75 | 1) Use lspci command and locate the PCI device with the SMBus controller: | |
76 | 00:0f.0 ISA bridge: ServerWorks OSB4 South Bridge (rev 4f) | |
77 | The line may vary for different chipsets. Please consult the driver source | |
78 | for all possible PCI ids (and lspci -n to match them). Lets assume the | |
79 | device is located at 00:0f.0. | |
80 | 2) Now you just need to change the value in 0xD2 register. Get it first with | |
81 | command: lspci -xxx -s 00:0f.0 | |
82 | If the value is 0x3 then you need to change it to 0x1 | |
83 | setpci -s 00:0f.0 d2.b=1 | |
84 | ||
85 | Please note that you don't need to do that in all cases, just when the SMBus is | |
86 | not working properly. | |
f9ba6c04 JD |
87 | |
88 | ||
89 | Hardware-specific issues | |
90 | ------------------------ | |
91 | ||
92 | This driver will refuse to load on IBM systems with an Intel PIIX4 SMBus. | |
93 | Some of these machines have an RFID EEPROM (24RF08) connected to the SMBus, | |
94 | which can easily get corrupted due to a state machine bug. These are mostly | |
95 | Thinkpad laptops, but desktop systems may also be affected. We have no list | |
96 | of all affected systems, so the only safe solution was to prevent access to | |
97 | the SMBus on all IBM systems (detected using DMI data.) | |
98 | ||
99 | For additional information, read: | |
ec1d86c4 | 100 | http://www.lm-sensors.org/browser/lm-sensors/trunk/README.thinkpad |