[PATCH] scx200_acb: Documentation update

Documentation update for the scx200_acb driver. Hopefully this will
help future users.

References:

[lm-sensors] Support of i2c-nscacb (April, May 2005)
  http://lists.lm-sensors.org/pipermail/lm-sensors/2005-April/011756.html
  http://lists.lm-sensors.org/pipermail/lm-sensors/2005-May/012043.html

[lm-sensors] making a geode i2c slave driver (April 2006)
  http://lists.lm-sensors.org/pipermail/lm-sensors/2006-April/015998.html

Kernel bug #6445
  http://bugzilla.kernel.org/show_bug.cgi?id=6445Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Documentation/i2c/busses/scx200_acb

@@ -2,14 +2,31 @@ Kernel driver scx200_acb
 
 Author: Christer Weinigel <wingel@nano-system.com>
 
+The driver supersedes the older, never merged driver named i2c-nscacb.
+
 Module Parameters
 -----------------
 
-* base: int
+* base: up to 4 ints
   Base addresses for the ACCESS.bus controllers on SCx200 and SC1100 devices
 
+  By default the driver uses two base addresses 0x820 and 0x840.
+  If you want only one base address, specify the second as 0 so as to
+  override this default.
+
 Description
 -----------
 
 Enable the use of the ACCESS.bus controller on the Geode SCx200 and
 SC1100 processors and the CS5535 and CS5536 Geode companion devices.
+
+Device-specific notes
+---------------------
+
+The SC1100 WRAP boards are known to use base addresses 0x810 and 0x820.
+If the scx200_acb driver is built into the kernel, add the following
+parameter to your boot command line:
+  scx200_acb.base=0x810,0x820
+If the scx200_acb driver is built as a module, add the following line to
+the file /etc/modprobe.conf instead:
+  options scx200_acb base=0x810,0x820