Based on kernel version 4.1. Page generated on 2015-06-28 12:13 EST.
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 7 * ServerWorks OSB4, CSB5, CSB6, HT-1000 and HT-1100 southbridges 8 Datasheet: Only available via NDA from ServerWorks 9 * ATI IXP200, IXP300, IXP400, SB600, SB700 and SB800 southbridges 10 Datasheet: Not publicly available 11 SB700 register reference available at: 12 http://support.amd.com/us/Embedded_TechDocs/43009_sb7xx_rrg_pub_1.00.pdf 13 * AMD SP5100 (SB700 derivative found on some server mainboards) 14 Datasheet: Publicly available at the AMD website 15 http://support.amd.com/us/Embedded_TechDocs/44413.pdf 16 * AMD Hudson-2, ML, CZ 17 Datasheet: Not publicly available 18 * Standard Microsystems (SMSC) SLC90E66 (Victory66) southbridge 19 Datasheet: Publicly available at the SMSC website http://www.smsc.com 20 21 Authors: 22 Frodo Looijaard <firstname.lastname@example.org> 23 Philip Edelbrock <email@example.com> 24 25 26 Module Parameters 27 ----------------- 28 29 * force: int 30 Forcibly enable the PIIX4. DANGEROUS! 31 * force_addr: int 32 Forcibly enable the PIIX4 at the given address. EXTREMELY DANGEROUS! 33 34 35 Description 36 ----------- 37 38 The PIIX4 (properly known as the 82371AB) is an Intel chip with a lot of 39 functionality. Among other things, it implements the PCI bus. One of its 40 minor functions is implementing a System Management Bus. This is a true 41 SMBus - you can not access it on I2C levels. The good news is that it 42 natively understands SMBus commands and you do not have to worry about 43 timing problems. The bad news is that non-SMBus devices connected to it can 44 confuse it mightily. Yes, this is known to happen... 45 46 Do 'lspci -v' and see whether it contains an entry like this: 47 48 0000:00:02.3 Bridge: Intel Corp. 82371AB/EB/MB PIIX4 ACPI (rev 02) 49 Flags: medium devsel, IRQ 9 50 51 Bus and device numbers may differ, but the function number must be 52 identical (like many PCI devices, the PIIX4 incorporates a number of 53 different 'functions', which can be considered as separate devices). If you 54 find such an entry, you have a PIIX4 SMBus controller. 55 56 On some computers (most notably, some Dells), the SMBus is disabled by 57 default. If you use the insmod parameter 'force=1', the kernel module will 58 try to enable it. THIS IS VERY DANGEROUS! If the BIOS did not set up a 59 correct address for this module, you could get in big trouble (read: 60 crashes, data corruption, etc.). Try this only as a last resort (try BIOS 61 updates first, for example), and backup first! An even more dangerous 62 option is 'force_addr=<IOPORT>'. This will not only enable the PIIX4 like 63 'force' foes, but it will also set a new base I/O port address. The SMBus 64 parts of the PIIX4 needs a range of 8 of these addresses to function 65 correctly. If these addresses are already reserved by some other device, 66 you will get into big trouble! DON'T USE THIS IF YOU ARE NOT VERY SURE 67 ABOUT WHAT YOU ARE DOING! 68 69 The PIIX4E is just an new version of the PIIX4; it is supported as well. 70 The PIIX/PIIX3 does not implement an SMBus or I2C bus, so you can't use 71 this driver on those mainboards. 72 73 The ServerWorks Southbridges, the Intel 440MX, and the Victory66 are 74 identical to the PIIX4 in I2C/SMBus support. 75 76 The AMD SB700, SB800, SP5100 and Hudson-2 chipsets implement two 77 PIIX4-compatible SMBus controllers. If your BIOS initializes the 78 secondary controller, it will be detected by this driver as 79 an "Auxiliary SMBus Host Controller". 80 81 If you own Force CPCI735 motherboard or other OSB4 based systems you may need 82 to change the SMBus Interrupt Select register so the SMBus controller uses 83 the SMI mode. 84 85 1) Use lspci command and locate the PCI device with the SMBus controller: 86 00:0f.0 ISA bridge: ServerWorks OSB4 South Bridge (rev 4f) 87 The line may vary for different chipsets. Please consult the driver source 88 for all possible PCI ids (and lspci -n to match them). Lets assume the 89 device is located at 00:0f.0. 90 2) Now you just need to change the value in 0xD2 register. Get it first with 91 command: lspci -xxx -s 00:0f.0 92 If the value is 0x3 then you need to change it to 0x1 93 setpci -s 00:0f.0 d2.b=1 94 95 Please note that you don't need to do that in all cases, just when the SMBus is 96 not working properly. 97 98 99 Hardware-specific issues 100 ------------------------ 101 102 This driver will refuse to load on IBM systems with an Intel PIIX4 SMBus. 103 Some of these machines have an RFID EEPROM (24RF08) connected to the SMBus, 104 which can easily get corrupted due to a state machine bug. These are mostly 105 Thinkpad laptops, but desktop systems may also be affected. We have no list 106 of all affected systems, so the only safe solution was to prevent access to 107 the SMBus on all IBM systems (detected using DMI data.) 108 109 For additional information, read: 110 http://www.lm-sensors.org/browser/lm-sensors/trunk/README