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Based on kernel version 3.15.4. Page generated on 2014-07-07 09:03 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 <frodol@dds.nl>
23		Philip Edelbrock <phil@netroedge.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
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