ppc4xx: Add Sequoia RAM-booting target
This patch adds another build target for the AMCC Sequoia PPC440EPx
eval board. This RAM-booting version is targeted for boards without
NOR FLASH (NAND booting) which need a possibility to initially
program their NAND FLASH. Using a JTAG debugger (e.g. BDI2000/3000)
configured to setup the SDRAM, this debugger can load this RAM-
booting image to the target address in SDRAM (in this case 0x1000000)
and start it there. Then U-Boot's standard NAND commands can be
used to program the NAND FLASH (e.g. "nand write ...").
Here the commands to load and start this image from the BDI2000:
440EPX>reset halt
440EPX>load 0x1000000 /tftpboot/sequoia/u-boot.bin
440EPX>go 0x1000000
Please note that this image automatically scans for an already
initialized SDRAM TLB (detected by EPN=0). This TLB will not be
cleared. This TLB doesn't need to be TLB #0, this RAM-booting
version will detect it and preserve it. So booting via BDI2000
will work and booting with a complete different TLB init via
U-Boot works as well.
Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/board/amcc/sequoia/init.S b/board/amcc/sequoia/init.S
index 4452d26..3c0e400 100644
--- a/board/amcc/sequoia/init.S
+++ b/board/amcc/sequoia/init.S
@@ -43,12 +43,19 @@
/* vxWorks needs this as first entry for the Machine Check interrupt */
tlbentry( 0x40000000, SZ_256M, 0, 0, AC_R|AC_W|AC_X|SA_G|SA_I )
+ /*
+ * The RAM-boot version skips the SDRAM TLB (identified by EPN=0). This
+ * entry is already configured for SDRAM via the JTAG debugger and mustn't
+ * be re-initialized by this RAM-booting U-Boot version.
+ */
+#ifndef CONFIG_SYS_RAMBOOT
/* TLB-entry for DDR SDRAM (Up to 2GB) */
#ifdef CONFIG_4xx_DCACHE
tlbentry( CONFIG_SYS_SDRAM_BASE, SZ_256M, CONFIG_SYS_SDRAM_BASE, 0, AC_R|AC_W|AC_X|SA_G)
#else
tlbentry( CONFIG_SYS_SDRAM_BASE, SZ_256M, CONFIG_SYS_SDRAM_BASE, 0, AC_R|AC_W|AC_X|SA_G|SA_I )
#endif
+#endif /* CONFIG_SYS_RAMBOOT */
/* TLB-entry for EBC */
tlbentry( CONFIG_SYS_BCSR_BASE, SZ_256M, CONFIG_SYS_BCSR_BASE, 1, AC_R|AC_W|AC_X|SA_G|SA_I )