i2c-piix4: Support AMD auxiliary SMBus controller
Some AMD chipsets, such as the SP5100, have an auxiliary SMBus
controller with a second set of registers. This patch adds
support for this auxiliary controller.
Tested on ASUS KCMA-D8 motherboard.
Signed-off-by: Andrew Armenia <andrew@asquaredlabs.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/Documentation/i2c/busses/i2c-piix4 b/Documentation/i2c/busses/i2c-piix4
index 475bb4a..1e6634f 100644
--- a/Documentation/i2c/busses/i2c-piix4
+++ b/Documentation/i2c/busses/i2c-piix4
@@ -8,6 +8,11 @@
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
Datasheet: Not publicly available
* Standard Microsystems (SMSC) SLC90E66 (Victory66) southbridge
@@ -68,6 +73,10 @@
The ServerWorks Southbridges, the Intel 440MX, and the Victory66 are
identical to the PIIX4 in I2C/SMBus support.
+The AMD SB700 and SP5100 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.