root/lm-sensors/trunk/doc/busses/i2c-ali15x3 @ 413

Kernel driver `i2c-ali5x3.o'

Status: Complete and tested

Supported adapters:
  * Acer Labs, Inc. ALI 1533 and 1543C
    Datasheet: Publicly available at the Acer Labs website

Author: Frodo Looijaard <frodol@dds.nl>, Philip Edelbrock
        <phil@netroedge.com>, and Mark D. Studebaker <mds@eng.paradyne.com>


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

(none)


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


Stability
---------
Complete and tested on the author's system.
Untested by others.
SMBus sometimes hangs on author's system when accessing W83781D,
cause unknown (see Issues below).


Supported Devices
-----------------
This is the driver for the SMB Host controller on
Acer Labs Inc. (ALI) M1541 and M1543C South Bridges.

The M1543C is a South bridge for desktop systems.
The M1541 is a South bridge for portable systems.
They are part of the following ALI chipsets:
   "Aladdin Pro 2": Includes the M1621 Slot 1 North bridge
   with AGP and 100MHz CPU Front Side bus

   "Aladdin V": Includes the M1541 Socket 7 North bridge
   with AGP and 100MHz CPU Front Side bus
   Some Aladdin V motherboards:
        Asus P5A
        Atrend ATC-5220
        BCM/GVC VP1541
        Biostar M5ALA
        Gigabyte GA-5AX
        Iwill XA100 Plus
        Micronics C200
        Microstar (MSI) MS-5169

   "Aladdin IV": Includes the M1541 Socket 7 North bridge
   with host bus up to 83.3 MHz.

For an overview of these chips see http://www.acerlabs.com
At this time the full data sheets on the web site are password protected,
however if you contact the ALI office in San Jose
they may give you the password.

The M1533/M1543C devices appear as FOUR separate devices
on the PCI bus. An output of lspci will show something similar
to the following:

  00:02.0 USB Controller: Acer Laboratories Inc. M5237 (rev 03)
  00:03.0 Bridge: Acer Laboratories Inc. M7101      <= THIS IS THE ONE WE NEED
  00:07.0 ISA bridge: Acer Laboratories Inc. M1533 (rev c3)
  00:0f.0 IDE interface: Acer Laboratories Inc. M5229 (rev c1)

** IMPORTANT **
** If you have a 1533 or 1543C on the board and you get
** "ali15x3.o: Error: Can't detect ali15x3!"
** then run lspci.
** If you see the 1533 and 5229 devices but NOT the 7101 device,
** then you MUST enable ACPI, the PMU, SMB, or something similar
** in the BIOS. If you can't figure out how to enable the
** 7101 device in the BIOS, you have to upgrade your BIOS.
** The driver won't work if it can't find the 7101 device.

The SMB controller is part of the 7101 device, which is an
ACPI-compliant Power Management Unit (PMU).

The whole 7101 device has to be enabled for the SMB to work.
You can't just enable the SMB alone.
The SMB and the ACPI have separate I/O spaces.
So we have to make sure that both the SMB and the ACPI
are mapped and enabled.


Features
--------
This driver controls the SMB Host only.
The SMB Slave controller on the M15X3 is not enabled.
This driver does not use interrupts.


Issues
------
This driver requests the I/O space both for the SMB and the ACPI
registers, just to be safe. It doesn't actually use the ACPI region.
It will therefore conflict with separate software
that accesses the ACPI registers?
To fix this, undefine MAP_ACPI.

On the author's ASUS P5A, the W83781D chip is on both the
ISA and the SMBus.

On the author's ASUS P5A, the W83781D chip hangs the whole
bus and this can only be resolved by powering off the computer.
The chip does not hang if an external device is attached
to the SMBus. There may be electrical problems on this board.
The EEPROM on the DRAM DIMM is accessible on the SMBus and
it does not hang the bus.


External Device Connection for ASUS P5A
---------------------------------------
On the author's ASUS P5A board,
the SMBus connector is between the 4th and 5th PCI
connector. The pinouts are:
        1. Clock
        2. no pin
        3. Ground
        4. Data
        5. +5V