ARM+LINUX移植攻略（九）U-boot-2009.08移植TE2440II开发板--支持Nandflash启动

哈尔滨理工大学软件工程专业08-7李万鹏原创作品，转载请标明出处

http://blog.csdn.net/woshixingaaa/archive/2011/02/17/6192146.aspx

从nandflash启动最关键的部分是rellocated，即代码重定位。s3c2440数据手册有这么一段，所以代码重定位是由nandflash控制器自动完成的，而不是一些人说的由CPU完成的。

在include/configs/TE2440II.h中添加nandflash控制器的定义：

/*

* NAND flash setting

*/

#if defined(CONFIG_CMD_NAND)

#define CONFIG_SYS_NAND_BASE 0x4e000000

#define CONFIG_SYS_MAX_NAND_DEVICE 1

#define CONFIG_MTD_NAND_VERIFY_WRITE 1

#define NAND_SAMSUNG_LP_OPTIONS 1 //大页要添加这个

#define CONFIG_NAND_S3C2440 1

#define CONFIG_S3C2440_NAND_BOOT 1

#define NAND_CTL_BASE 0x4E000000

#define oNFCONF 0x00

#define oNFCONT 0x04

#define oNFADDR 0x0c

#define oNFDATA 0x10

#define oNFCMD 0x08

#define oNFSTAT 0x20

#define oNFECC 0x2c

#endif

在

/*

* Command line configuration.

*/

下添加

#define CONFIG_CMD_NAND

修改环境变量那部分

//#undef CONFIG_ENV_IS_IN_FLASH 1

#define CONFIG_ENV_IS_IN_NAND 1

其次，修改cpu/arm920t/start.S这个文件，使u-boot从Nand Flash启动

为了让他自动识别是从norflash还是从nandflash启动添加，BWSCON的第2，1为即OM1，OM0。为00时是从nandflash启动，其他为从norflash启动，判断OM1和OM0，就可以让uboot自动识别启动方式。

#define BWSCON 0x48000000

ldr r0, =BWSCON

ldr r1,[r0]

ands r1, r1, #0x6

beq nand_boot

nor_boot:

#ifndef CONFIG_SKIP_RELOCATE_UBOOT

添加nandflash的启动代码，核心是relocated部分。首先设置nandflash控制器，然后将nandflash中从0开始的uboot复制到SDRAM中的TEXT_BASE处，TEXT_BASE在config.mk中定义，值为0x33f80000。复制好后，比较nandflash和SDRAM中的数据，如果前4K相同，表示搬移成功。下面的汇编代码注意ATPC标准规定r0~r3，用于参数传递和返回值。

/********************************************************/

//#define CONFIG_S3C2440_NAND_BOOT 1

nand_boot:

#define CONFIG_S3C2440_NAND_BOOT 1

#define NAND_CTL_BASE 0x4E000000

/* Offset */

#define oNFCONF 0x00

#define oNFCONT 0x04

#define oNFCMD 0x08

#define oNFSTAT 0x20

#define LENGTH_UBOOT 0x40000

@ reset NAND

mov r1, #NAND_CTL_BASE

ldr r2, =( (7<<12)|(7<<8)|(7<<4)|(0<<0) )

str r2, [r1, #oNFCONF]

ldr r2, [r1, #oNFCONF]

ldr r2, =((1<<4)|(0<<1)|(1<<0) ) @ Active low CE Control

str r2, [r1, #oNFCONT]

ldr r2, [r1, #oNFCONT]

ldr r2, =(0x6) @ RnB Clear

str r2, [r1, #oNFSTAT]

ldr r2, [r1, #oNFSTAT]

mov r2, #0xff @ RESET command

strb r2, [r1, #oNFCMD]

mov r3, #0 @ wait

nand1:

add r3, r3, #0x1

cmp r3, #0xa

blt nand1

nand2:

ldr r2, [r1, #oNFSTAT] @ wait ready

tst r2, #0x4

beq nand2

ldr r2, [r1, #oNFCONT]

orr r2, r2, #0x2 @ Flash Memory Chip Disable

str r2, [r1, #oNFCONT]

@ 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 U-Boot to RAM

ldr r0, =TEXT_BASE //传递给C代码的第一个参数：u-boot在RAM中的起始地址

mov r1, #0x0 //传递给C代码的第二个参数：Nand Flash的起始地址

mov r2, #LENGTH_UBOOT //传递给C代码的第三个参数：u-boot的长度大小

/**********************************************************/

/************************************************************/

bl nand_read_ll

tst r0, #0x0

beq ok_nand_read

bad_nand_read:

loop2:

b loop2 @ infinite loop

ok_nand_read:

@ verify

mov r0, #0

ldr r1, =TEXT_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 stack_setup

bne go_next

notmatch:

loop3:

b loop3 @ infinite loop

#endif

/* Set up the stack */

stack_setup:

ldr r0, _TEXT_BASE /* upper 128 KiB: relocated uboot */

sub r0, r0, #CONFIG_SYS_MALLOC_LEN /* malloc area */

sub r0, r0, #CONFIG_SYS_GBL_DATA_SIZE /* bdinfo */

#ifdef CONFIG_USE_IRQ

sub r0, r0, #(CONFIG_STACKSIZE_IRQ+CONFIG_STACKSIZE_FIQ)

#endif

sub sp, r0, #12 /* leave 3 words for abort-stack */

clear_bss:

ldr r0, _bss_start /* find start of bss segment */

ldr r1, _bss_end /* stop here */

mov r2, #0x00000000 /* clear */

clbss_l:str r2, [r0] /* clear loop... */

add r0, r0, #4

cmp r0, r1

ble clbss_l

ldr pc, _start_armboot

_start_armboot: .word start_armboot

#define STACK_BASE 0x33ff8000

#define STACK_SIZE 0x10000

.align 2

DW_STACK_START: .word STACK_BASE+STACK_SIZE-4

在board/samsung/TE2440II/目录下添加nand_read.c文件，内容如下，在K9F2G08的datasheet中有这么一段

所以地址由5个周期传完。前两个周期用来寻页内地址。后三个周期是页间寻址。1device=2048block=2048*64page=2048*64*(2k+64)Bytes

#include <config.h>

#include <linux/mtd/nand.h>

#define __REGb(x) (*(volatile unsigned char *)(x))

#define __REGw(x) (*(volatile unsigned short *)(x))

#define __REGi(x) (*(volatile unsigned int *)(x))

#define NF_BASE 0x4e000000

#define NFCONF __REGi(NF_BASE + 0x0)

#define NFCONT __REGi(NF_BASE + 0x4)

#define NFCMD __REGb(NF_BASE + 0x8)

#define NFADDR __REGb(NF_BASE + 0xc)

#define NFDATA __REGb(NF_BASE + 0x10)

#define NFDATA16 __REGw(NF_BASE + 0x10)

#define NFSTAT __REGb(NF_BASE + 0x20)

#define NFSTAT_BUSY (1 << 2)

#define nand_select() (NFCONT &= ~(1 << 1))

#define nand_deselect() (NFCONT |= (1 << 1))

#define nand_clear_RnB() (NFSTAT |= NFSTAT_BUSY)

static inline void nand_wait(void)

{

int i;

while (!(NFSTAT & NFSTAT_BUSY))

for (i=0; i<10; i++);

}

/* configuration for 2440 with 2048byte sized flash */

#define NAND_5_ADDR_CYCLE

#define NAND_PAGE_SIZE 2048

#define BAD_BLOCK_OFFSET NAND_PAGE_SIZE

#define NAND_BLOCK_MASK (NAND_PAGE_SIZE - 1)

#define NAND_BLOCK_SIZE (NAND_PAGE_SIZE * 64)

static int nand_read_page_ll(unsigned char *buf, unsigned long addr)

{

unsigned int i, page_num;

nand_clear_RnB();

NFCMD = NAND_CMD_READ0;

page_num = addr >> 11; /* addr / 2048 */

/* Write Address */

NFADDR = 0;

NFADDR = 0;

NFADDR = page_num & 0xff;

NFADDR = (page_num >> 8) & 0xff;

NFADDR = (page_num >> 16) & 0xff;

NFCMD = NAND_CMD_READSTART;

nand_wait();

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