1、启动模块修改
进入/cpu/arm1176/目录，修改start.S文件
首先找到需要修改的CONFIG_NAND_SPL汇编原码，修改如下：
#ifndef CONFIG_NAND_SPL /** flush v4 I/D caches*/ mov r0, #0 mcr p15, 0, r0, c7, c7, 0 /* flush v3/v4 cache */ mcr p15, 0, r0, c8, c7, 0 /* flush v4 TLB */ /** disable MMU stuff and caches*/ mrc p15, 0, r0, c1, c0, 0 bic r0, r0, #0x00002300 @ clear bits 13, 9:8 (--V- --RS) bic r0, r0, #0x00000087 @ clear bits 7, 2:0 (B--- -CAM) orr r0, r0, #0x00000002 @ set bit 2 (A) Align orr r0, r0, #0x00001000 @ set bit 12 (I) I-Cache //将原来之间的内容删除 mcr p15, 0, r0, c1, c0, 0 #endif
检索到“lowlevel_init”
添加如下内容，功能看注释
/* when we already run in ram, we don't need to relocate U-Boot.* and actually, memory controller must be configured before U-Boot* is running in ram.*/ldr r0, =0xff000fffbic r1, pc, r0 /* r0 <- current base addr of code */ldr r2, _TEXT_BASE /* r1 <- original base addr in ram */bic r2, r2, r0 /* r0 <- current base addr of code */cmp r1, r2 /* compare r0, r1 */beq after_copy /* r0 == r1 then skip flash copy */
此处顺便温习arm汇编
ldr汇编码与伪汇编码区别在于是否有“=”号
ldr汇编为 ldr r1, [r2]， 将 r2 当作地址放入 r1 寄存器，而intel与at&t汇编的mov指令是无法对地址直接操作的。
ldr伪汇编为 ldr r1, =<constant-expression>，将<constant-expression>放入 r1 中，可以是地址，这里所用为伪汇编
bic语法格式为 BIC{<cond>}{S} <Rd>,<Rn>,<shifter_operand>，shifter_operand取反后，和Rn与运算，值传回Rd
bic一般用于清零处理：
1、此处若系统从nandflash中启动，则pc小于4k，取反、与运算后，将0传给r1
此处_TEXT_BASE可能为0x57e00000或者0c7e00000，取反、与运算后，将0x00e00000传回r2
beq相等则跳转指令，此处 r1，r2不相等，故不跳转，继续往下执行
2、此处若系统从ram中启动，则此处的pc应该与_TEXT_BASE相等，故直接跳转至after_copy（复制
完成）处运行。
紧接着前面的代码添加下面一段代码：
#ifdef CONFIG_BOOT_NANDmov r0, #0x1000bl copy_from_nand #endif
此处的 bl 为调用子程序，接着上面的是因为未复制完成从新跳回 copy_from_nand 从新复制nandflash
然后找到_mmu_table_base，在它的#endif之后，添加如下代码，即上面所跳转的目标代码
/** copy U-Boot to SDRAM and jump to ram (from NAND or OneNAND)* r0: size to be compared* Load 1'st 2blocks to RAM because U-boot's size is larger than 1block(128k) size*/.globl copy_from_nand copy_from_nand:mov r10, lr /* save return address */mov r9, r0/* get ready to call C functions */ldr sp, _TEXT_PHY_BASE /* setup temp stack pointer */sub sp, sp, #12mov fp, #0 /* no previous frame, so fp=0 */mov r9, #0x1000bl copy_uboot_to_ram3: tst r0, #0x0bne copy_failedldr r0, =0x0c000000ldr r1, _TEXT_PHY_BASE 1: ldr r3, [r0], #4ldr r4, [r1], #4teq r3, r4bne compare_failed /* not matched */subs r9, r9, #4bne 1b4: mov lr, r10 /* all is OK */mov pc, lrcopy_failed:nop /* copy from nand failed */b copy_failedcompare_failed:nop /* compare failed */b compare_failed
至此，start.S文件修改完成。
接着在/cpu/arm1176/目录下添加一个nand_cp.c文件
代码如下
#include <common.h>#ifdef CONFIG_S3C64XX#include <asm/io.h>#include <linux/mtd/nand.h>#include <asm/arch/s3c6410.h>static int nandll_read_page (uchar *buf, ulong addr, int large_block){int i;int page_size = 512;/* 2K */if (large_block==1)page_size = 2048;/* 4K */if (large_block==2)page_size = 4096;NAND_ENABLE_CE();NFCMD_REG = NAND_CMD_READ0;/* Write Address */NFADDR_REG = 0;if (large_block)NFADDR_REG = 0;NFADDR_REG = (addr) & 0xff;NFADDR_REG = (addr >> 8) & 0xff;NFADDR_REG = (addr >> 16) & 0xff;if (large_block)NFCMD_REG = NAND_CMD_READSTART;NF_TRANSRnB();/* for compatibility(2460). u32 cannot be used. by scsuh */for(i=0; i < page_size; i++){*buf++ = NFDATA8_REG;}NAND_DISABLE_CE();return 0;}static int nandll_read_blocks (ulong dst_addr, ulong size, int large_block){uchar *buf = (uchar *)dst_addr;int i;uint page_shift = 9;if (large_block==1)page_shift = 11;/* Read pages */if(large_block==2)page_shift = 12;if(large_block == 2){/* Read pages */for (i = 0; i < 4; i++, buf+=(1<<(page_shift-1))){nandll_read_page(buf, i, large_block);}/* Read pages *//* 0x3c000 = 11 1100 0000 0000 0000 */for (i = 4; i < (0x3c000>>page_shift); i++, buf+=(1<<page_shift)){nandll_read_page(buf, i, large_block);}}else{for (i = 0; i < (0x3c000>>page_shift); i++, buf+=(1<<page_shift)){nandll_read_page(buf, i, large_block);}}return 0;}int copy_uboot_to_ram(void){int large_block = 0;int i;vu_char id;/*#define NAND_ENABLE_CE() (NFCONT_REG &= ~(1 << 1))#define NFCONT_REG__REG(ELFIN_NAND_BASE + NFCONT_OFFSET)#define __REG(x) (*((volatile u32 *)(x)))#define ELFIN_NAND_BASE 0x70200000#define NFCONT_OFFSET 0x04NFCONT_REG = ( *( (volatile u32 *) (0x70200004) ) )NFCONT 0x70200004 读/写NAND Flash 控制寄存器[0]1：NAND Flash 控制器使能*/NAND_ENABLE_CE();/*#define NFCMD_REG__REG(ELFIN_NAND_BASE + NFCMMD_OFFSET)#define ELFIN_NAND_BASE 0x70200000#define NFCMMD_OFFSET 0x08NFCMD_REG = ( *( (volatile u32 *) (0x70200008) ) )NFCMMD 0x70200008 NAND Flash 命令设置寄存器0#define NAND_CMD_READID 0x90*/NFCMD_REG = NAND_CMD_READID;/*#define NFADDR_REG__REG(ELFIN_NAND_BASE + NFADDR_OFFSET)#define ELFIN_NAND_BASE 0x70200000#define NFADDR_OFFSET 0x0CNFADDR_REG = ( *( (volatile u32 *) (0x7020000C) ) )NFADDR 0x7020000C NAND Flash 地址设置寄存器*/NFADDR_REG = 0x00;/*#define NFDATA8_REG__REGb(ELFIN_NAND_BASE + NFDATA_OFFSET)#define __REGb(x) (*(vu_char *)(x))NFDATA8_REG = ( *( (vu_char *) (0x70200010) ) )NFDATA 0x70200010 读/写NAND Flash 数据寄存器NAND Flash 读/烧写数据值用于I/O*//* wait for a while */for (i=0; i<200; i++);id = NFDATA8_REG;id = NFDATA8_REG;if (id > 0x80)large_block = 1;if(id == 0xd5)large_block = 2;/* read NAND Block.* 128KB ->240KB because of U-Boot size increase. by scsuh* So, read 0x3c000 bytes not 0x20000(128KB).*//*#define CONFIG_SYS_PHY_UBOOT_BASE(CONFIG_SYS_SDRAM_BASE + 0x07e00000)#define CONFIG_SYS_SDRAM_BASE 0x50000000CONFIG_SYS_PHY_UBOOT_BASE = 0x57e0 00000x3 c000 = 1M*/return nandll_read_blocks(CONFIG_SYS_PHY_UBOOT_BASE, 0x3c000, large_block);}#endif
然后在/cpu/arm1176/makefile中添加一个依赖到COBJS目标后面 COBJS = cpu.o nand_cp.o
接着在/nand_spl/board/samsung/smdk6410/Makefile中添加一个依赖到COBJS后面
COBJS = nand_boot.o nand_ecc.o s3c64xx.o nand_cp.o
补全规则
# from SoC directory $(obj)cpu_init.S:@rm -f $@@ln -s $(TOPDIR)/cpu/arm1176/s3c64xx/cpu_init.S $@ $(obj)nand_cp.c:@rm -f $@@ln -s $(TOPDIR)/cpu/arm1176/nand_cp.c $@
接着修改smdk6410.h文件（在/include/configs/目录下）：
1、添加宏定义
#define virt_to_phys(x) virt_to_phy_smdk6410(x) 2、用户名回显修改
#define CONFIG_SYS_PROMPT "SMDK6400 #" 3、添加smdk6410 ID
检索到MACH_TYPE，将其注释掉，然后添加smdk6410 ID如下
#define MACH_TYPE 1626 4、增加NAND config的内容 添加位置 /* NAND configuration */
#define NAND_DISABLE_CE()(NFCONT_REG |=(1<<1)) #define NAND_ENABLE_CE()(NFCONT_REG &=~(1<<1)) #define NF_TRANSRnB() do{while(!(NFSTAT_REG&(1<<0)));}while(0)
5、NAND flash 大小
//#define PHYS_SDRAM_1_SIZE 0x08000000 /* 128 MB in Bank #1 */ #define PHYS_SDRAM_1_SIZE 0x10000000 /* 256 MB in Bank #1 */
6、NAND flash块大小
/* NAND chip block size */ //#define CONFIG_SYS_NAND_BLOCK_SIZE (128 * 1024) #define CONFIG_SYS_NAND_BLOCK_SIZE (512 * 1024)
7、NAND flash页大小
/* NAND chip page size */ //#define CONFIG_SYS_NAND_PAGE_SIZE 2048 #define CONFIG_SYS_NAND_PAGE_SIZE 4096
8、位校验
/* NAND chip page per block count */ //#define CONFIG_SYS_NAND_PAGE_COUNT 64 #define CONFIG_SYS_NAND_PAGE_COUNT 128
9、更改内存分配空间 /** Size of malloc() pool*/ //#define CONFIG_SYS_MALLOC_LEN (CONFIG_ENV_SIZE + 1024 * 1024) #define CONFIG_SYS_MALLOC_LEN (CONFIG_ENV_SIZE + 512 * 1024)
10、修改开机延迟时间
#define CONFIG_BOOTDELAY 3 11、设置SDRAM大小
//#define PHYS_SDRAM_1_SIZE 0x08000000 /* 128 MB in Bank #1 */ #define PHYS_SDRAM_1_SIZE 0x10000000 /* 256 MB in Bank #1 */ /* 后面的大小自己设定 这里是256MB的SDRAM */
12、修改SDROM大小 //#define CONFIG_SYS_MEMTEST_END (CONFIG_SYS_SDRAM_BASE + 0x7e00000) /* 126MB in DRAM */ #define CONFIG_SYS_MEMTEST_END (CONFIG_SYS_SDRAM_BASE + 0x9e00000) /* 256MB in DRAM */
13、PWM设置
//#define CONFIG_SYS_HZ 1000 #define CONFIG_SYS_HZ 1562500
14、堆栈大小
/*-----------------------------------------------------------------------* Stack sizes** The stack sizes are set up in start.S using the settings below*/ //#define CONFIG_STACKSIZE 0x40000 /* regular stack 256KB */ #define CONFIG_STACKSIZE 0x80000 /* regular stack 512KB */
15、环境变量空间
//#define CONFIG_ENV_SIZE 0x4000 /* Total Size of Environment Sector */ #define CONFIG_ENV_SIZE 0x80000 /* Total Size of Environment Sector */
16、环境变量偏移地址
//#define CONFIG_ENV_OFFSET 0x0040000 #define CONFIG_ENV_OFFSET 0x0080000
17、BOOTCOMMAND
更改后的内容为
#ifdef CONFIG_ENABLE_MMU #define CONFIG_SYS_MAPPED_RAM_BASE 0xc0000000 #define CONFIG_BOOTCOMMAND "nand read 0xc0008000 0x100000 0x500000;" \"bootm 0xc0008000" #else #define CONFIG_SYS_MAPPED_RAM_BASE CONFIG_SYS_SDRAM_BASE #define CONFIG_BOOTCOMMAND "nand read 0x50008000 0x100000 0x500000;" \"bootm 0x50008000" #endif
然后开始添加内容到u-boot.lds，在目录cpu/arm1176/还有uboot根目录下面都有
完善如下代码段
. = ALIGN(4);.text :{ cpu/arm1176/start.o (.text)cpu/arm1176/s3c64xx/cpu_init.o (.text)board/samsung/smdk6410/lowlevel_init.o (.text)cpu/arm1176/nand_cp.o (.text)lib_arm/board.o (.text)*(.text)}
添加内容到u-boot-nand.lds，在目录/board/samsung/smdk6410中
完善如下代码
. = ALIGN(4);.text :{cpu/arm1176/start.o (.text)cpu/arm1176/s3c64xx/cpu_init.o (.text)board/samsung/smdk6410/lowlevel_init.o (.text)cpu/arm1176/nand_cp.o (.text)lib_arm/board.o (.text)*(.text)}
接着就可以回到根目录进行make了。
然后就可以看到你的uboot正式运转了…、
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