[deliverable/linux.git] / Documentation / i2c / busses / i2c-piix4

Kernel driver i2c-piix4

Supported adapters:
  * Intel 82371AB PIIX4 and PIIX4E
  * Intel 82443MX (440MX)
    Datasheet: Publicly available at the Intel website
  * ServerWorks OSB4, CSB5, CSB6, HT-1000 and HT-1100 southbridges
    Datasheet: Only available via NDA from ServerWorks
  * ATI IXP200, IXP300, IXP400, SB600, SB700 and SB800 southbridges
    Datasheet: Not publicly available
    SB700 register reference available at:
    http://support.amd.com/us/Embedded_TechDocs/43009_sb7xx_rrg_pub_1.00.pdf
  * AMD SP5100 (SB700 derivative found on some server mainboards)
    Datasheet: Publicly available at the AMD website
    http://support.amd.com/us/Embedded_TechDocs/44413.pdf
  * AMD Hudson-2, ML, CZ
    Datasheet: Not publicly available
  * Standard Microsystems (SMSC) SLC90E66 (Victory66) southbridge
    Datasheet: Publicly available at the SMSC website http://www.smsc.com

Authors: 
	Frodo Looijaard <frodol@dds.nl>
	Philip Edelbrock <phil@netroedge.com>


Module Parameters
-----------------

* force: int
  Forcibly enable the PIIX4. DANGEROUS!
* force_addr: int
  Forcibly enable the PIIX4 at the given address. EXTREMELY DANGEROUS!


Description
-----------

The PIIX4 (properly known as the 82371AB) is an Intel chip with a lot of
functionality. Among other things, it implements the PCI bus. One of its
minor functions is implementing a System Management Bus. This is a true 
SMBus - you can not access it on I2C levels. The good news is that it
natively understands SMBus commands and you do not have to worry about
timing problems. The bad news is that non-SMBus devices connected to it can
confuse it mightily. Yes, this is known to happen...

Do 'lspci -v' and see whether it contains an entry like this:

0000:00:02.3 Bridge: Intel Corp. 82371AB/EB/MB PIIX4 ACPI (rev 02)
	     Flags: medium devsel, IRQ 9

Bus and device numbers may differ, but the function number must be
identical (like many PCI devices, the PIIX4 incorporates a number of
different 'functions', which can be considered as separate devices). If you
find such an entry, you have a PIIX4 SMBus controller.

On some computers (most notably, some Dells), the SMBus is disabled by
default. If you use the insmod parameter 'force=1', the kernel module will
try to enable it. THIS IS VERY DANGEROUS! If the BIOS did not set up a
correct address for this module, you could get in big trouble (read:
crashes, data corruption, etc.). Try this only as a last resort (try BIOS
updates first, for example), and backup first! An even more dangerous
option is 'force_addr=<IOPORT>'. This will not only enable the PIIX4 like
'force' foes, but it will also set a new base I/O port address. The SMBus
parts of the PIIX4 needs a range of 8 of these addresses to function
correctly. If these addresses are already reserved by some other device,
you will get into big trouble! DON'T USE THIS IF YOU ARE NOT VERY SURE
ABOUT WHAT YOU ARE DOING!

The PIIX4E is just an new version of the PIIX4; it is supported as well.
The PIIX/PIIX3 does not implement an SMBus or I2C bus, so you can't use
this driver on those mainboards.

The ServerWorks Southbridges, the Intel 440MX, and the Victory66 are
identical to the PIIX4 in I2C/SMBus support.

The AMD SB700, SB800, SP5100 and Hudson-2 chipsets implement two
PIIX4-compatible SMBus controllers. If your BIOS initializes the
secondary controller, it will be detected by this driver as
an "Auxiliary SMBus Host Controller".

If you own Force CPCI735 motherboard or other OSB4 based systems you may need
to change the SMBus Interrupt Select register so the SMBus controller uses
the SMI mode.

1) Use lspci command and locate the PCI device with the SMBus controller:
   00:0f.0 ISA bridge: ServerWorks OSB4 South Bridge (rev 4f)
   The line may vary for different chipsets. Please consult the driver source
   for all possible PCI ids (and lspci -n to match them). Lets assume the
   device is located at 00:0f.0.
2) Now you just need to change the value in 0xD2 register. Get it first with
   command: lspci -xxx -s 00:0f.0
   If the value is 0x3 then you need to change it to 0x1
   setpci  -s 00:0f.0 d2.b=1

Please note that you don't need to do that in all cases, just when the SMBus is
not working properly.


Hardware-specific issues
------------------------

This driver will refuse to load on IBM systems with an Intel PIIX4 SMBus.
Some of these machines have an RFID EEPROM (24RF08) connected to the SMBus,
which can easily get corrupted due to a state machine bug. These are mostly
Thinkpad laptops, but desktop systems may also be affected. We have no list
of all affected systems, so the only safe solution was to prevent access to
the SMBus on all IBM systems (detected using DMI data.)

For additional information, read:
http://www.lm-sensors.org/browser/lm-sensors/trunk/README
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
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
2a2f7404 AA	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
032f708b	16	* AMD Hudson-2, ML, CZ
76b3e28f	17	Datasheet: Not publicly available
1da177e4 LT	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!
1da177e4 LT	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
7aadb8f9	73	The ServerWorks Southbridges, the Intel 440MX, and the Victory66 are
1da177e4 LT	74	identical to the PIIX4 in I2C/SMBus support.
1da177e4 LT	75
a94dd00f RM	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".
2a2f7404	80
54aaa1ca RM	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.
f9ba6c04 JD	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:
0ea6e611	110	http://www.lm-sensors.org/browser/lm-sensors/trunk/README