arm: mvebu: Add option to use UART xmodem protocol via kwboot

This patch enables the use of the kwboot tool, to boot mainline U-Boot
on the Marvell Armada XP/38x SoC's. This is done by returning to the
SoC's BootROM after SPL has initialized the SDRAM. We need to make sure
to not reconfigure the internal register space and MBARs. Otherwise
the BootROM will not be able to continue after SPL jumps back to it.

To use this feature, please don't forget to change the BOOT_FROM line
in your board specfic kwbimage.cfg file this way:

    BOOT_FROM uart

Tested on these Marvell eval boards:
DB-MV784MP-GP - Armada XP
DB-88F6820-GP - Armada 38x

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Dirk Eibach <eibach@gdsys.de>
Cc: Kevin Smith <kevin.smith@elecsyscorp.com>
Cc: Luka Perkov <luka.perkov@sartura.hr>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/arm/mach-mvebu/include/mach/cpu.h b/arch/arm/mach-mvebu/include/mach/cpu.h
index 6fa41736e2..5e8bf0c4ce 100644
--- a/arch/arm/mach-mvebu/include/mach/cpu.h
+++ b/arch/arm/mach-mvebu/include/mach/cpu.h
@@ -119,6 +119,8 @@ int mvebu_mbus_probe(struct mbus_win windows[], int count);
 int mvebu_soc_family(void);
 u32 mvebu_get_nand_clock(void);
 
+void return_to_bootrom(void);
+
 int mv_sdh_init(unsigned long regbase, u32 max_clk, u32 min_clk, u32 quirks);
 
 /*