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