prepare joining at91rm9200 into at91

* prepare joining at91 and at91rm9200
 * add modified copy of soc files to cpu/arm920t/at91 to make
   possible to compile at91rm9200 boards in at91 tree instead
   of at91rm9200
 * add header files with c structure defs for AT91 MC, ST and TC
 * the new cpu files are using at91 c structure soc access
 * please read README.soc-at91 for details

Signed-off-by: Jens Scharsig <js_at_ng@scharsoft.de>

1 files changed, 23 insertions, 0 deletions

diff --git a/doc/README.at91-soc b/doc/README.at91-soc
index bed035c88d2..425fc588f04 100644
--- a/doc/README.at91-soc
+++ b/doc/README.at91-soc
@@ -39,3 +39,26 @@ The method for updating
 3. add new structures for SoC access
 4. Convert arch, driver and boards file to new SoC
 5. remove legacy code, if all boards and drives are ready
+
+ Join AT91 and AT91RM9200 SoC
+==============================
+
+Approximately 95 percent of AT91 and AT91RM9200 SoC parts are the same.
+So, we should use the chance, to join both archs togetter.
+
+To do this follow step needed:
+
+1. change Makefile
+	@$(MKCONFIG) $(@:_config=) arm arm920t board vendor at91rm9200
+  to
+	@$(MKCONFIG) $(@:_config=) arm arm920t board vendor at91
+2. remove CONFIG_AT91_LEGACY in board config
+3. convert boards file to new SoC access
+4. convert or change drivers
+
+To support the joining process, a new SoC dir (at91) has been adding to
+arm920t arch directory. This directory contains files like at91rm9200 dir, but
+uses the new c structure Soc access. The advantage of this is, we don't merge
+old Soc access code and new code while the board are not converted.
+Finally we can delete the whole at91rm9200 dir, if all board support the
+new AT91-SoC access.