sbc8548: enable ability to boot from alternate flash

This board has an 8MB soldered on flash, and a 64MB SODIMM
flash module.  Normally the board boots from the 8MB flash,
but the hardware can be configured for booting from the 64MB
flash as well by swapping CS0 and CS6.  This can be handy
for recovery purposes, or for supporting u-boot and VxBoot
at the same time.

To support this in u-boot, we need to have different BR0/OR0
and BR6/OR6 settings in place for when the board is configured
in this way, and a different TEXT_BASE needs to be used due
to the larger sector size of the 64MB flash module.

We introduce the suffix _8M and _64M for the BR0/BR6 and the
OR0/OR6 values so it is clear which is being used to map what
specific device.

The larger sector size (512k) of the alternate flash needs
a larger malloc pool, otherwise you'll get failures when
running saveenv, so bump it up accordingly.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

1 files changed, 30 insertions, 4 deletions

diff --git a/doc/README.sbc8548 b/doc/README.sbc8548
index 5fa9c93685..e6b8abe2b3 100644
--- a/doc/README.sbc8548
+++ b/doc/README.sbc8548
@@ -86,6 +86,33 @@ The "md" steps in the above are just a precautionary step that allow
 you to confirm the u-boot version that was downloaded, and then confirm
 that it was copied to flash.
 
+The above assumes that you are using the default board settings which
+have u-boot in the 8MB flash, tied to /CS0.
+
+If you are running the default 8MB /CS0 settings but want to store an
+image in the SODIMM that is built with CONFIG_SYS_ALT_BOOT enabled,
+(as a backup, etc) then the steps will become:
+
+	tftp u-boot.bin
+	md 200000 10
+	protect off all
+	era eff00000 efffffff
+	cp.b 200000 eff00000 100000
+	md eff00000 10
+	protect on all
+
+Finally, if you are running the alternate 64MB /CS0 settings and want
+to update the in-use u-boot image, then (again with CONFIG_SYS_ALT_BOOT
+enabled) the steps will become:
+
+	tftp u-boot.bin
+	md 200000 10
+	protect off all
+	era fff00000 ffffffff
+	cp.b 200000 fff00000 100000
+	md fff00000 10
+	protect on all
+
 
 Hardware Reference:
 ===================
@@ -127,10 +154,9 @@ JP19		PCI mode	PCI		PCI-X
 onto /CS0 and the SODIMM flash on /CS6 (default).  When JP12
 is jumpered parallel to the LBC-SDRAM, then /CS0 is for the
 SODIMM flash and /CS6 is for the boot flash.  Note that in this
-alternate setting, you also need to switch SW2.8 to ON.  Currently
-u-boot doesn't support booting off the SODIMM in this alternate
-setting without manually altering BR0/OR0 and BR6/OR6 in the
-board config file appropriately.
+alternate setting, you also need to switch SW2.8 to ON.
+See the setting CONFIG_SYS_ALT_BOOT if you want to use this setting
+and boot u-boot from the 64MB SODIMM
 
 
 	Switches: