Add support for AMCC Sequoia PPC440EPx eval board

- Add support for PPC440EPx & PPC440GRx
- Add support for PPC440EP(x)/GR(x) NAND controller
  in cpu/ppc4xx directory
- Add NAND boot functionality for Sequoia board,
  please see doc/README.nand-boot-ppc440 for details
- This Sequoia NAND image doesn't support environment
  in NAND for now. This will be added in a short while.
Patch by Stefan Roese, 07 Sep 2006

1 files changed, 36 insertions, 0 deletions

diff --git a/doc/README.nand-boot-ppc440 b/doc/README.nand-boot-ppc440
new file mode 100644
index 0000000000..a82a10ee6a
--- /dev/null
+++ b/doc/README.nand-boot-ppc440
@@ -0,0 +1,36 @@
+-----------------------------
+NAND boot on PPC440 platforms
+-----------------------------
+
+This document describes the U-Boot NAND boot feature as it
+is implemented for the AMCC Sequoia (PPC440EPx) board.
+
+The PPC440EP(x)/GR(x) cpu's can boot directly from NAND FLASH,
+completely without NOR FLASH. This can be done by using the NAND
+boot feature of the 440 NAND flash controller (NDFC).
+
+Here a short desciption of the different boot stages:
+
+a) IPL (Initial Program Loader, integrated inside CPU)
+------------------------------------------------------
+Will load first 4k from NAND (SPL) into cache and execute it from there.
+
+b) SPL (Secondary Program Loader)
+---------------------------------
+Will load special U-Boot version (NUB) from NAND and execute it. This SPL
+has to fit into 4kByte. It sets up the CPU and configures the SDRAM
+controller and the NAND controller so that the special U-Boot image can be
+loaded from NAND to SDRAM.
+This special image is build in the directory "nand_spl".
+
+c) NUB (NAND U-Boot)
+--------------------
+This NAND U-Boot (NUB) is a special U-Boot version which can be started
+from RAM. Therefore it mustn't (re-)configure the SDRAM controller.
+
+On 440EPx the SPL is copied to internal SRAM before the NAND controller
+is set up. While still running from cache, I experienced problems accessing
+the NAND controller.
+
+
+September 07 2006, Stefan Roese <sr@denx.de>