kernel

linux-6.8.1/Documentation/i2c/busses/i2c-ali15x3.rst

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+=========================
+Kernel driver i2c-ali15x3
+=========================
+
+Supported adapters:
+  * Acer Labs, Inc. ALI 1533 and 1543C (south bridge)
+
+    Datasheet: Now under NDA
+	http://www.ali.com.tw/
+
+Authors:
+	- Frodo Looijaard <frodol@dds.nl>,
+	- Philip Edelbrock <phil@netroedge.com>,
+	- Mark D. Studebaker <mdsxyz123@yahoo.com>
+
+Module Parameters
+-----------------
+
+* force_addr: int
+    Initialize the base address of the i2c controller
+
+
+Notes
+-----
+
+The force_addr parameter is useful for boards that don't set the address in
+the BIOS. Does not do a PCI force; the device must still be present in
+lspci. Don't use this unless the driver complains that the base address is
+not set.
+
+Example::
+
+    modprobe i2c-ali15x3 force_addr=0xe800
+
+SMBus periodically hangs on ASUS P5A motherboards and can only be cleared
+by a power cycle. Cause unknown (see Issues below).
+
+
+Description
+-----------
+
+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 (Generally doesn't work because the BIOS doesn't
+	  enable the 7101 device!)
+	- 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 M1533 or M1543C on the board and you get
+   "ali15x3: 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.
+
+   The driver won't work if it can't find the M7101 device.
+
+The SMB controller is part of the M7101 device, which is an ACPI-compliant
+Power Management Unit (PMU).
+
+The whole M7101 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.
+We make sure that the SMB is enabled. We leave the ACPI alone.
+
+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 for only the SMB
+registers. It doesn't use the ACPI region.
+
+On the ASUS P5A motherboard, there are several reports that
+the SMBus will hang and this can only be resolved by
+powering off the computer. It appears to be worse when the board
+gets hot, for example under heavy CPU load, or in the summer.
+There may be electrical problems on this board.
+On the P5A, the W83781D sensor chip is on both the ISA and
+SMBus. Therefore the SMBus hangs can generally be avoided
+by accessing the W83781D on the ISA bus only.