arm:at91: enable ROM loadable atmel image

For sama5d3xek we need to modify the SPL image for correct detection by ROM
code.

Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>
Tested-by: Bo Shen <voice.shen@atmel.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/doc/README.atmel_pmecc b/doc/README.atmel_pmecc
index cf8373b..cc0f73d 100644
--- a/doc/README.atmel_pmecc
+++ b/doc/README.atmel_pmecc
@@ -27,3 +27,24 @@ Take AT91SAM9X5EK as an example, the board definition file likes:
 #define CONFIG_ATMEL_NAND_HW_PMECC	1
 #define CONFIG_PMECC_CAP		2
 #define CONFIG_PMECC_SECTOR_SIZE	512
+
+How to enable PMECC header for direct programmable boot.bin
+-----------------------------------------------------------
+2014-05-19 Andreas Bießmann <andreas.devel@googlemail.com>
+
+The usual way to program SPL into NAND flash is to use the SAM-BA Atmel tool.
+This however is often not usable when doing field updates. To be able to
+program a SPL binary into NAND flash we need to add the PMECC header to the
+binary before. Chapter '12.4.4.1 NAND Flash Boot: NAND Flash Detection' in
+sama5d3 SoC spec (as of 03. April 2014) defines how this PMECC header has to
+look like. In order to do so we have a new image type added to mkimage to
+generate this PMECC header and integrated this into the build process of SPL.
+
+To enable the generation of atmel PMECC header for SPL one need to define
+CONFIG_SPL_GENERATE_ATMEL_PMECC_HEADER. The required parameters are taken from
+board configuration and compiled into the host tools atmel_pmecc_params. This
+tool will be called in build process to parametrize mkimage for atmelimage
+type. The mkimage tool has intentionally _not_ compiled in those parameters.
+
+The mkimage image type atmelimage also set the 6'th interrupt vector to the
+correct value. This feature can also be used to setup a boot.bin for MMC boot.