u-boot1.1.6移植到Nand Flash（即从sbc2410的NandFlash启动boot,这样的代码烧到NorFlash里启动会出错）

本文详细介绍了如何在S3C2410硬件平台上，通过NAND Flash实现代码定位，修改Makefile、Start.S文件及sbc2410x.h文件来优化U-Boot启动过程。包括引入NAND Flash读取函数、调整代码布局和初始化流程，以实现从NAND Flash到RAM的高效代码定位与复制。

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参考：http://blog.youkuaiyun.com/bekars/article/details/710888

我的s3c2410硬件：

Nand Flash：K9s1208V

Nor Flash：Amd29LV160BB（最大2M，当然要自己扩充，默认是512k）

SDRAM ：HY（64M,现代）

1)在board/sbc2410x加入NAND Flash读函数，建立nand_read.c，加入如下内容(copy from vivi)：
#include <config.h>

#define __REGb(x) (*(volatile unsigned char *)(x))
#define __REGi(x) (*(volatile unsigned int *)(x))
#define NF_BASE  0x4e000000
#define NFCONF  __REGi(NF_BASE + 0x0)
#define NFCMD  __REGb(NF_BASE + 0x4)
#define NFADDR  __REGb(NF_BASE + 0x8)
#define NFDATA  __REGb(NF_BASE + 0xc)
#define NFSTAT  __REGb(NF_BASE + 0x10)

#define BUSY 1
inline void wait_idle(void) {
int i;

while(!(NFSTAT & BUSY))
for(i=0; i<10; i++);
}

#define NAND_SECTOR_SIZE 512
#define NAND_BLOCK_MASK (NAND_SECTOR_SIZE - 1)

/* low level nand read function */
int
nand_read_ll(unsigned char *buf, unsigned long start_addr, int size)
{
int i, j;

    if ((start_addr & NAND_BLOCK_MASK) || (size & NAND_BLOCK_MASK)) {
        return -1; /* invalid alignment */
    }

    /* chip Enable */
    NFCONF &= ~0x800;
    for(i=0; i<10; i++);

    for(i=start_addr; i < (start_addr + size);) {
      /* READ0 */
      NFCMD = 0;

      /* Write Address */
      NFADDR = i & 0xff;
      NFADDR = (i >> 9) & 0xff;
      NFADDR = (i >> 17) & 0xff;
      NFADDR = (i >> 25) & 0xff;

wait_idle();

      for(j=0; j < NAND_SECTOR_SIZE; j++, i++) {
*buf = (NFDATA & 0xff);
buf++;
      }
    }

/* chip Disable */
NFCONF |= 0x800; /* chip disable */

return 0;
}

2）修改board/sbc2410x/Makefile为
OBJS := bks2410.o flash.o nand_read.o

3）修改cpu/arm920t/start.S文件
在ldr pc, _start_armboot之前加入：
#ifdef CONFIG_S3C2410_NAND_BOOT
bl    copy_myself

@ jump to ram
ldr   r1, =on_the_ram
add pc, r1, #0
nop
nop
1:    b     1b          @ infinite loop

on_the_ram:
#endif

在_start_armboot: .word start_armboot之后加入：
#ifdef CONFIG_S3C2410_NAND_BOOT
copy_myself:
mov r10, lr
@ reset NAND
mov r1, #NAND_CTL_BASE
ldr   r2, =0xf830           @ initial value
str   r2, [r1, #oNFCONF]
ldr   r2, [r1, #oNFCONF]
bic r2, r2, #0x800              @ enable chip
str   r2, [r1, #oNFCONF]
mov r2, #0xff         @ RESET command
strb r2, [r1, #oNFCMD]
mov r3, #0                   @ wait

1:add r3, r3, #0x1
cmp r3, #0xa
blt   1b
2:ldr   r2, [r1, #oNFSTAT]      @ wait ready
tst    r2, #0x1
beq 2b
ldr   r2, [r1, #oNFCONF]
orr r2, r2, #0x800              @ disable chip
str   r2, [r1, #oNFCONF]

@ get read to call C functions (for nand_read())
ldr sp, DW_STACK_START @ setup stack pointer
mov fp, #0 @ no previous frame, so fp=0

@ copy vivi to RAM
ldr   r0, =UBOOT_RAM_BASE
mov     r1, #0x0
mov r2, #0x20000
bl    nand_read_ll
tst    r0, #0x0
beq ok_nand_read

#ifdef CONFIG_DEBUG_LL
bad_nand_read:
ldr   r0, STR_FAIL
ldr   r1, SerBase
bl    PrintWord
1:b     1b          @ infinite loop
#endif

ok_nand_read:
#ifdef CONFIG_DEBUG_LL
ldr   r0, STR_OK
ldr   r1, SerBase
bl    PrintWord
#endif

@ verify
mov r0, #0
ldr   r1, =UBOOT_RAM_BASE
mov r2, #0x400     @ 4 bytes * 1024 = 4K-bytes
go_next:
ldr   r3, [r0], #4
ldr   r4, [r1], #4
teq   r3, r4
bne notmatch
subs r2, r2, #4
beq done_nand_read
bne go_next

notmatch:
#ifdef CONFIG_DEBUG_LL
sub r0, r0, #4
ldr   r1, SerBase
bl    PrintHexWord
ldr   r0, STR_FAIL
ldr   r1, SerBase
bl    PrintWord
#endif
1:b     1b
done_nand_read:
#ifdef CONFIG_DEBUG_LL
ldr   r0, STR_OK
ldr   r1, SerBase
bl    PrintWord
#endif
mov pc, r10
@ clear memory
@ r0: start address
@ r1: length
mem_clear:
mov r2, #0
mov r3, r2
mov r4, r2
mov r5, r2
mov r6, r2
mov r7, r2
mov r8, r2
mov r9, r2

clear_loop:
stmia r0!, {r2-r9}
subs r1, r1, #(8 * 4)
bne clear_loop
mov pc, lr

#endif @ CONFIG_S3C2410_NAND_BOOT

在文件的最后加入：
.align 2
DW_STACK_START:
.word STACK_BASE+STACK_SIZE-4

4）修改include/configs/sbc2410x.h文件，添加如下内容：
/*
* Nandflash Boot
*/

由于NandFlash启动已经实现了代码定位，所以

#define CONFIG_SKIP_RELOCATE_UBOOT 1这样Start.S中的下面就不会执行：

                       #ifndef CONFIG_SKIP_RELOCATE_UBOOT
                              relocate:               /* relocate U-Boot to RAM        */
    adr   r0, _start       /* r0 <- current position of code   */
      ldr   r1, _TEXT_BASE       /* test if we run from flash or RAM */
      cmp     r0, r1                  /* don't reloc during debug         */
beq     stack_setup

ldr   r2, _armboot_start
   ldr   r3, _bss_start
   sub   r2, r3, r2       /* r2 <- size of armboot            */
   add   r2, r0, r2       /* r2 <- source end address         */

                           copy_loop:
   ldmia   r0!, {r3-r10}       /* copy from source address [r0]    */
stmia   r1!, {r3-r10}       /* copy to   target address [r1]    */
cmp   r0, r2           /* until source end addreee [r2]    */
ble   copy_loop
                          #endif   /* CONFIG_SKIP_RELOCATE_UBOOT */

#define CONFIG_S3C2410_NAND_BOOT 1
#define STACK_BASE    0x33f00000
#define STACK_SIZE    0x8000
#define UBOOT_RAM_BASE    0x33f80000
/* NAND Flash Controller */
#define NAND_CTL_BASE            0x4E000000
#define bINT_CTL(Nb)        __REG(INT_CTL_BASE + (Nb))
/* Offset */
#define oNFCONF               0x00
#define oNFCMD                0x04
#define oNFADDR               0x08
#define oNFDATA               0x0c
#define oNFSTAT               0x10
#define oNFECC                0x14

5）重新编译u-boot
make all ARCH=arm