sbc8548: relocate 64MB user flash to sane boundary
The current situation has the 64MB user flash at an awkward
alignment; shifted back from 0xfc00_0000 by 8M, to leave an 8MB hole
for the soldered on boot flash @ EOM. But to switch to optionally
supporting booting off the 64MB flash, the 64MB will then be mapped
at the sane address of 0xfc00_0000.
This leads to awkward things when programming the 64MB flash prior
to transitioning to it -- i.e. even though the chip spans from
0xfb80_0000 to 0xff7f_ffff, you would have to program a u-boot image
into the two sectors from 0xfbf0_0000 --> 0xfbff_ffff so that it was
in the right place when JP12/SW2.8 were switched to make the 64MB on
/CS0. (i.e. the chip is only looking at the bits in mask 0x3ff_ffff)
We also have to have three TLB entries responsible for dealing with
mapping the 64MB flash due to this 8MB of misalignment.
In the end, there is address space from 0xec00_0000 to 0xefff_ffff
where we can map it, and then the transition from booting from one
config to the other will be a simple 0xec --> 0xfc mapping. Plus we
can toss out a TLB entry.
Note that TLB0 is kept at 64MB and not shrunk down to the 8MB boot
flash; this means we won't have to change it when the alternate
config uses the full 64MB for booting, in TLB0.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/doc/README.sbc8548 b/doc/README.sbc8548
index 6cbe12f..5fa9c93 100644
--- a/doc/README.sbc8548
+++ b/doc/README.sbc8548
@@ -100,6 +100,9 @@
Sodimm flash:
intel V28F128Jx, 16384x8 (4 devices) at 0xfb80_0000
+ Note that this address reflects the default setting for
+ the JTAG debugging tools, but since the alignment is
+ rather inconvenient, u-boot puts it at 0xec00_0000.
Jumpers:
@@ -187,9 +190,12 @@
0000_0000 0fff_ffff MCS0,1 64 DDR2 (256MB)
f000_0000 f7ff_ffff CS3,4 32 LB SDRAM (128MB)
f800_0000 f8b0_1fff CS5 - EPLD
-fb80_0000 ff7f_ffff CS6 32 SODIMM flash (64MB)
+fb80_0000 ff7f_ffff CS6 32 SODIMM flash (64MB) [*]
ff80_0000 ffff_ffff CS0 8 Boot flash (8MB)
+[*] fb80 represents the default programmed by WR JTAG register files,
+ but u-boot places the flash at either ec00 or fc00 based on JP12.
+
The EPLD on CS5 demuxes the following devices at the following offsets:
offset size width device