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ccf988b6 | 1 | ======================= |
1da177e4 | 2 | Kernel driver i2c-piix4 |
ccf988b6 | 3 | ======================= |
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4 | |
5 | Supported adapters: | |
6 | * Intel 82371AB PIIX4 and PIIX4E | |
7 | * Intel 82443MX (440MX) | |
8 | Datasheet: Publicly available at the Intel website | |
506a8b6c | 9 | * ServerWorks OSB4, CSB5, CSB6, HT-1000 and HT-1100 southbridges |
1da177e4 | 10 | Datasheet: Only available via NDA from ServerWorks |
60693e5a | 11 | * ATI IXP200, IXP300, IXP400, SB600, SB700 and SB800 southbridges |
02e0c5d5 | 12 | Datasheet: Not publicly available |
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13 | SB700 register reference available at: |
14 | http://support.amd.com/us/Embedded_TechDocs/43009_sb7xx_rrg_pub_1.00.pdf | |
15 | * AMD SP5100 (SB700 derivative found on some server mainboards) | |
16 | Datasheet: Publicly available at the AMD website | |
17 | http://support.amd.com/us/Embedded_TechDocs/44413.pdf | |
032f708b | 18 | * AMD Hudson-2, ML, CZ |
76b3e28f | 19 | Datasheet: Not publicly available |
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20 | * Hygon CZ |
21 | Datasheet: Not publicly available | |
1da177e4 LT |
22 | * Standard Microsystems (SMSC) SLC90E66 (Victory66) southbridge |
23 | Datasheet: Publicly available at the SMSC website http://www.smsc.com | |
24 | ||
ccf988b6 MCC |
25 | Authors: |
26 | - Frodo Looijaard <frodol@dds.nl> | |
27 | - Philip Edelbrock <phil@netroedge.com> | |
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28 | |
29 | ||
30 | Module Parameters | |
31 | ----------------- | |
32 | ||
33 | * force: int | |
34 | Forcibly enable the PIIX4. DANGEROUS! | |
35 | * force_addr: int | |
36 | Forcibly enable the PIIX4 at the given address. EXTREMELY DANGEROUS! | |
1da177e4 LT |
37 | |
38 | ||
39 | Description | |
40 | ----------- | |
41 | ||
42 | The PIIX4 (properly known as the 82371AB) is an Intel chip with a lot of | |
43 | functionality. Among other things, it implements the PCI bus. One of its | |
ccf988b6 | 44 | minor functions is implementing a System Management Bus. This is a true |
1da177e4 LT |
45 | SMBus - you can not access it on I2C levels. The good news is that it |
46 | natively understands SMBus commands and you do not have to worry about | |
47 | timing problems. The bad news is that non-SMBus devices connected to it can | |
48 | confuse it mightily. Yes, this is known to happen... | |
49 | ||
ccf988b6 | 50 | Do ``lspci -v`` and see whether it contains an entry like this:: |
1da177e4 | 51 | |
ccf988b6 MCC |
52 | 0000:00:02.3 Bridge: Intel Corp. 82371AB/EB/MB PIIX4 ACPI (rev 02) |
53 | Flags: medium devsel, IRQ 9 | |
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54 | |
55 | Bus and device numbers may differ, but the function number must be | |
56 | identical (like many PCI devices, the PIIX4 incorporates a number of | |
57 | different 'functions', which can be considered as separate devices). If you | |
58 | find such an entry, you have a PIIX4 SMBus controller. | |
59 | ||
60 | On some computers (most notably, some Dells), the SMBus is disabled by | |
61 | default. If you use the insmod parameter 'force=1', the kernel module will | |
62 | try to enable it. THIS IS VERY DANGEROUS! If the BIOS did not set up a | |
63 | correct address for this module, you could get in big trouble (read: | |
64 | crashes, data corruption, etc.). Try this only as a last resort (try BIOS | |
65 | updates first, for example), and backup first! An even more dangerous | |
66 | option is 'force_addr=<IOPORT>'. This will not only enable the PIIX4 like | |
53b77471 | 67 | 'force' does, but it will also set a new base I/O port address. The SMBus |
1da177e4 LT |
68 | parts of the PIIX4 needs a range of 8 of these addresses to function |
69 | correctly. If these addresses are already reserved by some other device, | |
70 | you will get into big trouble! DON'T USE THIS IF YOU ARE NOT VERY SURE | |
71 | ABOUT WHAT YOU ARE DOING! | |
72 | ||
73 | The PIIX4E is just an new version of the PIIX4; it is supported as well. | |
74 | The PIIX/PIIX3 does not implement an SMBus or I2C bus, so you can't use | |
75 | this driver on those mainboards. | |
76 | ||
7aadb8f9 | 77 | The ServerWorks Southbridges, the Intel 440MX, and the Victory66 are |
1da177e4 LT |
78 | identical to the PIIX4 in I2C/SMBus support. |
79 | ||
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80 | The AMD SB700, SB800, SP5100 and Hudson-2 chipsets implement two |
81 | PIIX4-compatible SMBus controllers. If your BIOS initializes the | |
82 | secondary controller, it will be detected by this driver as | |
83 | an "Auxiliary SMBus Host Controller". | |
2a2f7404 | 84 | |
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85 | If you own Force CPCI735 motherboard or other OSB4 based systems you may need |
86 | to change the SMBus Interrupt Select register so the SMBus controller uses | |
87 | the SMI mode. | |
88 | ||
53b77471 | 89 | 1) Use ``lspci`` command and locate the PCI device with the SMBus controller: |
54aaa1ca RM |
90 | 00:0f.0 ISA bridge: ServerWorks OSB4 South Bridge (rev 4f) |
91 | The line may vary for different chipsets. Please consult the driver source | |
53b77471 | 92 | for all possible PCI ids (and ``lspci -n`` to match them). Let's assume the |
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93 | device is located at 00:0f.0. |
94 | 2) Now you just need to change the value in 0xD2 register. Get it first with | |
53b77471 | 95 | command: ``lspci -xxx -s 00:0f.0`` |
ccf988b6 | 96 | If the value is 0x3 then you need to change it to 0x1: |
53b77471 | 97 | ``setpci -s 00:0f.0 d2.b=1`` |
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98 | |
99 | Please note that you don't need to do that in all cases, just when the SMBus is | |
100 | not working properly. | |
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101 | |
102 | ||
103 | Hardware-specific issues | |
104 | ------------------------ | |
105 | ||
106 | This driver will refuse to load on IBM systems with an Intel PIIX4 SMBus. | |
107 | Some of these machines have an RFID EEPROM (24RF08) connected to the SMBus, | |
108 | which can easily get corrupted due to a state machine bug. These are mostly | |
109 | Thinkpad laptops, but desktop systems may also be affected. We have no list | |
110 | of all affected systems, so the only safe solution was to prevent access to | |
111 | the SMBus on all IBM systems (detected using DMI data.) |