一、代码搬运
u-boot启动时，需要 copy u-boot to ram 的过程，通过自己定义的 nand_read.c实现，该步骤与u-boot- 1.1.6移植(一)同，需要注意的是增加对nand flash支持后编译出来的bin文件将大于128KB，所以修改start.S即可：
@ copy UBOOT to RAM
ldr r0, _TEXT_BASE
mov r1, #0x0
mov r2, #0x20000 //改为mov r2,#0x40000,这是FS2410分配给u-boot的存储空间
bl nand_read_ll
二、修改配置文件 include/configs/s3c2410.h 使支持NAND
#define CONFIG_COMMANDS \
(CONFIG_CMD_DFL | \
CFG_CMD_CACHE | \
CFG_CMD_ENV | \
CFG_CMD_NET | \
CFG_CMD_PING | \
CFG_CMD_NAND | \
\
\
\
CFG_CMD_REGINFO | \
CFG_CMD_DATE | \
CFG_CMD_ELF)
#define CFG_NAND_BASE 0x4E000000
#define CFG_MAX_NAND_DEVICE 1
#define NAND_MAX_CHIPS 1
#define CFG_ENV_IS_IN_NAND 1
#define CMD_SAVEENV
#define CFG_ENV_SIZE 0x10000
#define CFG_ENV_OFFSET 0x30000
#define CONFIG_BOOTDELAY 3
#define CONFIG_BOOTARGS "noinitrd root=/dev/mtdblock2 init=/linuxrc devfs=mount console=ttySAC0,115200"
#define CONFIG_ETHADDR 08:00:3e:26:0a:5b
#define CONFIG_NETMASK 255.255.255.0
#define CONFIG_IPADDR 202.193.74.101
#define CONFIG_SERVERIP 202.193.74.235
#define CONFIG_BOOTCOMMAND "nand read 0x30007fc0 0x40000 0x1c0000; bootm 0x30007fc0"
三、建立cpu/arm920t/s3c24x0/nand_flash.c，实现board_nand_init函数
《嵌入式Linux应用开发完全手册》中介召的nand_flash.c包含对S3C2440的支持，在这里一并列出，供日后参考。
(1)针对S3C2410、S3C2440 NAND Flash控制器的不同来定义一些数据结构和函数，在include/s3c24x0.h 文件中增加S3C2440_NAND数据结构。
typedef struct {
S3C24X0_REG32 NFCONF;
S3C24X0_REG32 NFCONT;
S3C24X0_REG32 NFCMD;
S3C24X0_REG32 NFADDR;
S3C24X0_REG32 NFDATA;
S3C24X0_REG32 NFMECCD0;
S3C24X0_REG32 NFMECCD1;
S3C24X0_REG32 NFSECCD;
S3C24X0_REG32 NFSTAT;
S3C24X0_REG32 NFESTAT0;
S3C24X0_REG32 NFESTAT1;
S3C24X0_REG32 NFMECC0;
S3C24X0_REG32 NFMECC1;
S3C24X0_REG32 NFSECC;
S3C24X0_REG32 NFSBLK;
S3C24X0_REG32 NFEBLK;
} S3C2440_NAND;
(2)在 include/s3c2410.h 文件中仿照 S3C2410_GetBase_NAND函数定义S3C2440_GetBase_NAND函数。
static inline S3C2440_NAND * const S3C2440_GetBase_NAND(void)
{
return (S3C2440_NAND * const)S3C2410_NAND_BASE;
}
(3) cpu/arm920t/s3c24x0/nand_flash.c，添加nand_flash.c文件
#include
#if (CONFIG_COMMANDS & CFG_CMD_NAND) && !defined(CFG_NAND_LEGACY)
#include
#include
DECLARE_GLOBAL_DATA_PTR;
#define S3C2410_NFSTAT_READY (1<<0)
#define S3C2410_NFCONF_nFCE (1<<11)
#define S3C2440_NFSTAT_READY (1<<0)
#define S3C2440_NFCONT_nFCE (1<<1)
static void s3c2410_nand_select_chip(struct mtd_info *mtd, int chip)
{
S3C2410_NAND * const s3c2410nand = S3C2410_GetBase_NAND();
if (chip == -1) {
s3c2410nand->NFCONF |= S3C2410_NFCONF_nFCE;
} else {
s3c2410nand->NFCONF &= ~S3C2410_NFCONF_nFCE;
}
}
static void s3c2410_nand_hwcontrol(struct mtd_info *mtd, int cmd)
{
S3C2410_NAND * const s3c2410nand = S3C2410_GetBase_NAND();
struct nand_chip *chip = mtd->priv;
switch (cmd) {
case NAND_CTL_SETNCE:
case NAND_CTL_CLRNCE:
printf("%s: called for NCE\n", __FUNCTION__);
break;
case NAND_CTL_SETCLE:
chip->IO_ADDR_W = (void *)&s3c2410nand->NFCMD;
break;
case NAND_CTL_SETALE:
chip->IO_ADDR_W = (void *)&s3c2410nand->NFADDR;
break;
default:
chip->IO_ADDR_W = (void *)&s3c2410nand->NFDATA;
break;
}
}
static int s3c2410_nand_devready(struct mtd_info *mtd)
{
S3C2410_NAND * const s3c2410nand = S3C2410_GetBase_NAND();
return (s3c2410nand->NFSTAT & S3C2410_NFSTAT_READY);
}
static void s3c2440_nand_select_chip(struct mtd_info *mtd, int chip)
{
S3C2440_NAND * const s3c2440nand = S3C2440_GetBase_NAND();
if (chip == -1) {
s3c2440nand->NFCONT |= S3C2440_NFCONT_nFCE;
} else {
s3c2440nand->NFCONT &= ~S3C2440_NFCONT_nFCE;
}
}
static void s3c2440_nand_hwcontrol(struct mtd_info *mtd, int cmd)
{
S3C2440_NAND * const s3c2440nand = S3C2440_GetBase_NAND();
struct nand_chip *chip = mtd->priv;
switch (cmd) {
case NAND_CTL_SETNCE:
case NAND_CTL_CLRNCE:
printf("%s: called for NCE\n", __FUNCTION__);
break;
case NAND_CTL_SETCLE:
chip->IO_ADDR_W = (void *)&s3c2440nand->NFCMD;
break;
case NAND_CTL_SETALE:
chip->IO_ADDR_W = (void *)&s3c2440nand->NFADDR;
break;
default:
chip->IO_ADDR_W = (void *)&s3c2440nand->NFDATA;
break;
}
}
static int s3c2440_nand_devready(struct mtd_info *mtd)
{
S3C2440_NAND * const s3c2440nand = S3C2440_GetBase_NAND();
return (s3c2440nand->NFSTAT & S3C2440_NFSTAT_READY);
}
static void s3c24x0_nand_inithw(void)
{
S3C2410_NAND * const s3c2410nand = S3C2410_GetBase_NAND();
S3C2440_NAND * const s3c2440nand = S3C2440_GetBase_NAND();
#define TACLS 0
#define TWRPH0 4
#define TWRPH1 2
if (gd->bd->bi_arch_number == MACH_TYPE_SMDK2410)
{
s3c2410nand->NFCONF = (1<<15)|(1<<12)|(1<<11)|(TACLS<<8)|(TWRPH0<<4)|(TWRPH1<<0);
}
else
{
s3c2440nand->NFCONF = (TACLS<<12)|(TWRPH0<<8)|(TWRPH1<<4);
s3c2440nand->NFCONT = (1<<4)|(0<<1)|(1<<0);
}
}
void board_nand_init(struct nand_chip *chip)
{
S3C2410_NAND * const s3c2410nand = S3C2410_GetBase_NAND();
S3C2440_NAND * const s3c2440nand = S3C2440_GetBase_NAND();
s3c24x0_nand_inithw();
if (gd->bd->bi_arch_number == MACH_TYPE_SMDK2410) {
chip->IO_ADDR_R = (void *)&s3c2410nand->NFDATA;
chip->IO_ADDR_W = (void *)&s3c2410nand->NFDATA;
chip->hwcontrol = s3c2410_nand_hwcontrol;
chip->dev_ready = s3c2410_nand_devready;
chip->select_chip = s3c2410_nand_select_chip;
chip->options = 0;
} else {
chip->IO_ADDR_R = (void *)&s3c2440nand->NFDATA;
chip->IO_ADDR_W = (void *)&s3c2440nand->NFDATA;
chip->hwcontrol = s3c2440_nand_hwcontrol;
chip->dev_ready = s3c2440_nand_devready;
chip->select_chip = s3c2440_nand_select_chip;
chip->options = 0;
}
chip->eccmode = NAND_ECC_SOFT;
}
#endif
四、将nand_flash.c编入 u-boot，修改cpu/arm920t/s3c24x0/Makefile文件
COBJS = i2c.o interrupts.o serial.o speed.o \
usb_ohci.o nand_flash.o
至此，编译生成 u-boot.bin 并烧入NAND Flash,启动，便可以引导内核了。
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