1-----------------------------
2NAND boot on PPC440 platforms
3-----------------------------
4
5This document describes the U-Boot NAND boot feature as it
6is implemented for the AMCC Sequoia (PPC440EPx) board.
7
8The PPC440EP(x)/GR(x) cpu's can boot directly from NAND FLASH,
9completely without NOR FLASH. This can be done by using the NAND
10boot feature of the 440 NAND flash controller (NDFC).
11
12Here a short description of the different boot stages:
13
14a) IPL (Initial Program Loader, integrated inside CPU)
15------------------------------------------------------
16Will load first 4k from NAND (SPL) into cache and execute it from there.
17
18b) SPL (Secondary Program Loader)
19---------------------------------
20Will load special U-Boot version (NUB) from NAND and execute it. This SPL
21has to fit into 4kByte. It sets up the CPU and configures the SDRAM
22controller and the NAND controller so that the special U-Boot image can be
23loaded from NAND to SDRAM.
24This special image is build in the directory "nand_spl".
25
26c) NUB (NAND U-Boot)
27--------------------
28This NAND U-Boot (NUB) is a special U-Boot version which can be started
29from RAM. Therefore it mustn't (re-)configure the SDRAM controller.
30
31On 440EPx the SPL is copied to internal SRAM before the NAND controller
32is set up. While still running from cache, I experienced problems accessing
33the NAND controller.
34
35
36Example: Build and install NAND boot image for Sequoia (440EPx):
37
38a) Configure for sequoia with NAND boot support:
39# make sequoia_nand_config
40
41b) Build image(s)
42# make
43
44This will generate the SPL image in the "nand_spl" directory:
45nand_spl/u-boot-spl.bin
46Also another image is created spanning a whole NAND block (16kBytes):
47nand_spl/u-boot-spl-16k.bin
48The main NAND U-Boot image is generated in the toplevel directory:
49u-boot.bin
50A combined image of u-boot-spl-16k.bin and u-boot.bin is also created:
51u-boot-nand.bin
52
53This image should be programmed at offset 0 in the NAND flash:
54
55# tftp 100000 /tftpboot/sequoia/u-boot-nand.bin
56# nand erase 0 60000
57# nand write 100000 0 60000
58
59
60September 07 2006, Stefan Roese <sr@denx.de>
61