u-boot-2011.06 is started from nandflash based on the transplantation of s3c2440 development board

Due to the price, NandFlash is more advantageous than NorFlash for storing large amounts of data. However, programs cannot be run directly on NandFlash, so S3C2440 provides a mechanism where the system automatically copies the first 4K of the content in NandFlash to an internal SRAM called "Steppingstone". Using this SRAM, the programmer needs to copy the program to the rest of the SRAM and then run the program just copied to the SRAM.

This article introduces how to start u-boot in nandflash. The working principle is similar to the nandflash startup process of the smdk6400 development board that comes with u-boot-2011.06. That is, the final generated burning file is u-boot-nand.bin, which consists of two files:

nand_spl/u-boot-spl-16k.bin + u-boot.bin = u-boot-nand.bin

The size of the u-boot-spl-16k.bin file is exactly 4k. After the system starts, the content of this 4k is automatically copied to Steppingstone. After completing the necessary hardware initialization, u-boot-spl-16k.bin copies the u-boot.bin file to the specified memory, and then runs the u-boot.bin file that has been copied to the memory.

The following is a detailed description of the transplant process:

1. boards.cfg

Remove the following statement in this file:

zhaocj2440 arm arm920t - samsung s3c24x0

2. Makefile

Add the following statement around line 1050 in the file:

################################################ #######################

ARM920T Systems

################################################ #######################

zhaocj2440_config: unconfig

@mkdir-p $(obj)include $(obj)board/samsung/zhaocj2440

@mkdir-p $(obj)nand_spl/board/samsung/zhaocj2440

@echo"#define CONFIG_NAND_U_BOOT" > $(obj)include/config.h

@echo"CONFIG_NAND_U_BOOT = y" >> $(obj)include/config.mk

@echo"RAM_TEXT = 0x33000000" >>$(obj)board/samsung/zhaocj2440/config.tmp

@$(MKCONFIG)zhaocj2440 arm arm920t - samsung s3c24x0

@echo"CONFIG_NAND_U_BOOT = y" >> $(obj)include/config.mk

3. board/samsung/zhaocj2440/

Create a config.mk file in this directory with the following content:

sinclude$(OBJTREE)/board/$(BOARDDIR)/config.tmp

ifndef CONFIG_NAND_SPL

CONFIG_SYS_TEXT_BASE =$(RAM_TEXT)

else

CONFIG_SYS_TEXT_BASE = 0

endif

4. nand_spl/board/Samsung/

Create a zhaocj2440 directory in this directory, and then create three files, config.mk, Makefile, and u-boot.lds, in the zhaocj2440 directory. The contents are as follows:

config.mk file:

include$(TOPDIR)/board/$(BOARDDIR)/config.mk

#PAD_TO used to generate a 4kByte binaryneeded for the combined image

# ->PAD_TO = CONFIG_SYS_TEXT_BASE +4096

PAD_TO :=$(shell expr $$[$(CONFIG_SYS_TEXT_BASE) + 4096])

ifeq ($(debug),1)

PLATFORM_CPPFLAGS += -DDEBUG

endif

Makefile:

CONFIG_NAND_SPL = y

include $(TOPDIR)/config.mk

include$(TOPDIR)/nand_spl/board/$(BOARDDIR)/config.mk

nandobj :=$(OBJTREE)/nand_spl/

LDSCRIPT=$(TOPDIR)/nand_spl/board/$(BOARDDIR)/u-boot.lds

LDFLAGS := -T $(nandobj)u-boot.lds -Ttext$(CONFIG_SYS_TEXT_BASE) $(LDFLAGS)

$(LDFLAGS_FINAL)

AFLAGS += -DCONFIG_NAND_SPL

CFLAGS += -DCONFIG_NAND_SPL

SOBJS =start.o lowlevel_init.o

COBJS =nand_boot.o s3c2440_nand.o

SRCS :=$(addprefix $(obj),$(SOBJS:.o=.S) $(COBJS:.o=.c))

OBJS :=$(addprefix $(obj),$(SOBJS) $(COBJS))

__OBJS :=$(SOBJS) $(COBJS)

LNDIR :=$(nandobj)board/$(BOARDDIR)

ALL =$(nandobj)u-boot-spl $(nandobj)u-boot-spl.bin $(nandobj)u-boot-spl-16k.bin

all: $(obj).depend$(ALL)

$(nandobj)u-boot-spl-16k.bin:$(nandobj)u-boot-spl

$(OBJCOPY)${OBJCFLAGS} --pad-to=$(PAD_TO) -O binary $< $@

$(nandobj)u-boot-spl.bin: $(nandobj)u-boot-spl

$(OBJCOPY)${OBJCFLAGS} -O binary $< $@

$(nandobj)u-boot-spl: $(OBJS) $(nandobj)u-boot.lds

cd$(LNDIR) && $(LD) $(LDFLAGS) $(__OBJS)

-Map$(nandobj)u-boot-spl.map

-o$(nandobj)u-boot-spl

$(nandobj)u-boot.lds: $(LDSCRIPT)

$(CPP)$(CPPFLAGS) $(LDPPFLAGS) -ansi -D__ASSEMBLY__ -P - <$^ >$@

# create symbolic links for common files

# from cpu directory

$(obj)start.S:

@rm -f $@

@ln-s $(TOPDIR)/arch/arm/cpu/arm920t/start.S $@

# from board directory

$(obj)lowlevel_init.S:

@rm -f $@

@ln-s $(TOPDIR)/board/samsung/zhaocj2440/lowlevel_init.S $@

# from nand_spl directory

$(obj)nand_boot.c:

@rm -f $@

@ln-s $(TOPDIR)/nand_spl/nand_boot.c $@

$(obj)s3c2440_nand.c:

@rm -f $@

@ln-s $(TOPDIR)/drivers/mtd/nand/s3c2440_nand.c$@

################################################ #######################

$(obj)%.o: $(obj)%.S

$(CC)$(AFLAGS) -c -o $@ $<

$(obj)%.o: $(obj)%.c

$(CC)$(CFLAGS) -c -o $@ $<

# defines $(obj).depend target

include $(SRCTREE)/rules.mk

sinclude $(obj).depend

################################################ #######################

u-boot.lds file:

OUTPUT_FORMAT("elf32-littlearm","elf32-littlearm", "elf32-littlearm")

OUTPUT_ARCH(arm)

ENTRY(_start)

SECTIONS

{

.= 0x00000000;

.= ALIGN(4);

.text :

{

start.o (.text)

nand_boot.o (.text)

*(.text)

}

.= ALIGN(4);

.rodata: { *(SORT_BY_ALIGNMENT(SORT_BY_NAME(.rodata*))) }

.= ALIGN(4);

.data: { *(.data) }

.= ALIGN(4);

.got: { *(.got) }

__u_boot_cmd_start= .;

.u_boot_cmd: { *(.u_boot_cmd) }

__u_boot_cmd_end= .;

.= ALIGN(4);

.rel.dyn: {

__rel_dyn_start = .;

*(.rel*)

__rel_dyn_end = .;

}

.dynsym: {

__dynsym_start= .;

*(.dynsym)

}

_end= .;

.bss__rel_dyn_start (OVERLAY) : {

__bss_start = .;

*(.bss)

.= ALIGN(4);

__bss_end__ = .;

}

}

5.arch/arm/cpu/arm920t/start.s

Modify the following content in this file, where the code marked in red is the part that needs to be modified:

.globl _start

_start: b start_code

#ifndef CONFIG_NAND_SPL // by zhaocj

ldr pc, _undefined_instruction

ldr pc, _software_interrupt

ldr pc, _prefetch_abort

ldr pc, _data_abort

ldr pc, _not_used

ldr pc, _irq

ldr pc, _fiq

_undefined_instruction: .word undefined_instruction

_software_interrupt: .word software_interrupt

_prefetch_abort: .word prefetch_abort

_data_abort: .word data_abort

_not_used: .wordnot_used

_irq: .wordirq

_fiq: .wordfiq

_pad: .word 0x12345678 //by zhaocj start

#else

. = _start + 64

#endif //by zhaocj end

.balignl16,0xdeadbeef

…………

/* Set stackpointer in internal RAM to callboard_init_f */

#ifndef CONFIG_NAND_SPL //by zhaocj

call_board_init_f:

ldr sp, =(CONFIG_SYS_INIT_SP_ADDR)

bic sp, sp, #7 /* 8-byte alignment for ABIcompliance */

ldr r0,=0x00000000

bl board_init_f

…………

blcoloured_LED_init

blred_LED_on

#endif

#endif // by zhaocj

/*

* We are done. Do notreturn, instead branch to second part of board

* initialization, now running from RAM.

*/

#ifdef CONFIG_NAND_SPL

ldr sp,=0x33200000 //by zhaocj

ldr r0, _nand_boot_ofs

mov pc, r0

_nand_boot_ofs:

.wordnand_boot

…………

mov lr, ip

mov pc, lr

#endif /* CONFIG_SKIP_LOWLEVEL_INIT */

#ifndef CONFIG_NAND_SPL //by zhaocj

/*

*************************************************** ***********************

*

* Interrupt handling

*

*************************************************** ***********************

*/

@

@ IRQ stack frame.

@

#define S_FRAME_SIZE 72

…………

fiq:

get_bad_stack

bad_save_user_regs

bl do_fiq

#endif

#endif //by zhaocj

6. include/configs/zhaocj2440.h

Modify the following content in this file:

Comment out the following statement:

#define CONFIG_SYS_TEXT_BASE 0x0

Add the following statement:

#ifndef CONFIG_NAND_SPL

#define CONFIG_SKIP_LOWLEVEL_INIT

#endif

Comment out the following statement:

#define CONFIG_ENV_ADDR (CONFIG_SYS_FLASH_BASE +0x080000)

#define CONFIG_ENV_IS_IN_FLASH

#define CONFIG_ENV_SIZE 0x10000

Add the following statement:

#define CONFIG_SYS_NAND_U_BOOT_DST 0x33000000 /*NUB load-addr */

#define CONFIG_SYS_NAND_U_BOOT_START CONFIG_SYS_NAND_U_BOOT_DST /* NUB start-addr */

#define CONFIG_SYS_NAND_U_BOOT_OFFS (4 * 1024) /* Offset to RAM U-Boot image */

#define CONFIG_SYS_NAND_U_BOOT_SIZE 0x80000 /*Size of RAM U-Boot image */

/* NAND chip page size */

#define CONFIG_SYS_NAND_PAGE_SIZE 2048

/* NAND chip block size */

#define CONFIG_SYS_NAND_BLOCK_SIZE (128 * 1024)

/* NAND chip page per block count */

#define CONFIG_SYS_NAND_PAGE_COUNT 64

/* Location of the bad-block label */

#define CONFIG_SYS_NAND_BAD_BLOCK_POS 0

/* Extra address cycle for > 128MiB */

#define CONFIG_SYS_NAND_5_ADDR_CYCLE

/* Size of the block protected by one OOB(Spare Area in Samsung terminology) */

#define CONFIG_SYS_NAND_ECCSIZE CONFIG_SYS_NAND_PAGE_SIZE

/* Number of ECC bytes per OOB - S3C6400 calculates 4 bytes ECC in 1-bitmode */

#define CONFIG_SYS_NAND_ECCBYTES 4

/* Number of ECC-blocks per NAND page */

#define CONFIG_SYS_NAND_ECCSTEPS (CONFIG_SYS_NAND_PAGE_SIZE / CONFIG_SYS_NAND_ECCSIZE)

/* Size of a single OOB region */

#define CONFIG_SYS_NAND_OOBSIZE 64

/* Number of ECC bytes per page */

#define CONFIG_SYS_NAND_ECCTOTAL (CONFIG_SYS_NAND_ECCBYTES *CONFIG_SYS_NAND_ECCSTEPS)

/* ECC byte positions */

#define CONFIG_SYS_NAND_ECCPOS {40, 41, 42, 43, 44, 45, 46, 47,

48, 49, 50, 51, 52, 53, 54, 55,

56, 57, 58, 59, 60, 61, 62, 63}

/* Put environment copies after the end ofU-Boot owned RAM */

#define CONFIG_NAND_ENV_DST (0x33000000 + 0x80000)

#define CONFIG_ENV_OFFSET 0x80000

#define CONFIG_ENV_IS_IN_NAND

#define CONFIG_ENV_SIZE 0x4000 /* Total Size of Environment Sector */

7. drivers/mtd/cfi_flash.c

In line 2156 of the file (inside the flash_init function), change the size variable to:

unsigned long size = 0x200000;