uboot源码之时钟和串口修改
在uboot源码中添加单板
首先添加单板相关文件, board目录下将原来的2410复制成2440，在其基础上修改 cp board/samsung/smdk2410 board/samsung/smdk2440 -rf
添加单板的配置文件，include目录下 复制 cp include/configs/smdk2410.h include/configs/smdk2440.h
修改boards.cfg文件，将smdk2410的配置复制为smdk2440
配置： make smdk2440_config
编译： make
修改源代码支持启动
修改时钟
原来源码中是先设置时钟分频，再设置时钟大小的，这样在设置时钟大小之前有些程序运行就只能在外部12M晶振下运行，所以修改代码，将board_early_init_f函数中的时钟先屏蔽，
然后修改时钟大小
int board_early_init_f(void)
{
struct s3c24x0_clock_power * const clk_power =
s3c24x0_get_base_clock_power();
struct s3c24x0_gpio * const gpio = s3c24x0_get_base_gpio();
/* to reduce PLL lock time, adjust the LOCKTIME register */
//writel(0xFFFFFF, &clk_power->locktime);
/* configure MPLL */
//writel((M_MDIV << 12) + (M_PDIV << 4) + M_SDIV,
// &clk_power->mpllcon);
/* some delay between MPLL and UPLL */
pll_delay(4000);
/* configure UPLL */
writel((U_M_MDIV << 12) + (U_M_PDIV << 4) + U_M_SDIV,
&clk_power->upllcon);
/* some delay between MPLL and UPLL */
pll_delay(8000);
/* set up the I/O ports */
writel(0x007FFFFF, &gpio->gpacon);
writel(0x00044555, &gpio->gpbcon);
writel(0x000007FF, &gpio->gpbup);
writel(0xAAAAAAAA, &gpio->gpccon);
writel(0x0000FFFF, &gpio->gpcup);
writel(0xAAAAAAAA, &gpio->gpdcon);
writel(0x0000FFFF, &gpio->gpdup);
writel(0xAAAAAAAA, &gpio->gpecon);
writel(0x0000FFFF, &gpio->gpeup);
writel(0x000055AA, &gpio->gpfcon);
writel(0x000000FF, &gpio->gpfup);
writel(0xFF95FFBA, &gpio->gpgcon);
writel(0x0000FFFF, &gpio->gpgup);
writel(0x002AFAAA, &gpio->gphcon);
writel(0x000007FF, &gpio->gphup);
return 0;
}start.s
/*
* mask all IRQs by setting all bits in the INTMR - default
*/
mov r1, #0xffffffff
ldr r0, =INTMSK
str r1, [r0]
# if defined(CONFIG_S3C2410)
ldr r1, =0x3ff
ldr r0, =INTSUBMSK
str r1, [r0]
# endif
#endif
/* 2. 设置时钟 */
ldr r0, =0x4c000014
// mov r1, #0x03; // FCLK:HCLK:PCLK=1:2:4, HDIVN=1,PDIVN=1
mov r1, #0x05; // FCLK:HCLK:PCLK=1:4:8
str r1, [r0]
/* 如果HDIVN非0，CPU的总线模式应该从“fast bus mode”变为“asynchronous bus mode” */
mrc p15, 0, r1, c1, c0, 0 /* 读出控制寄存器 */
orr r1, r1, #0xc0000000 /* 设置为“asynchronous bus mode” */
mcr p15, 0, r1, c1, c0, 0 /* 写入控制寄存器 */
#define S3C2440_MPLL_400MHZ ((0x5c<<12)|(0x01<<4)|(0x01))
/* MPLLCON = S3C2440_MPLL_200MHZ */
ldr r0, =0x4c000004
ldr r1, =S3C2440_MPLL_400MHZ
str r1, [r0]
/* 启动ICACHE */
mrc p15, 0, r0, c1, c0, 0 @ read control reg
orr r0, r0, #(1<<12)
mcr p15, 0, r0, c1, c0, 0 @ write it back
修改内存
smdk2440/lowlevel_init.S lowlevel_init:
SMRDATA:
.long 0x22011110 //BWSCON
.long 0x00000700 //BANKCON0
.long 0x00000700 //BANKCON1
.long 0x00000700 //BANKCON2
.long 0x00000700 //BANKCON3
.long 0x00000700 //BANKCON4
.long 0x00000700 //BANKCON5
.long 0x00018005 //BANKCON6
.long 0x00018005 //BANKCON7
.long 0x008C04F4 // REFRESH
.long 0x000000B1 //BANKSIZE
.long 0x00000030 //MRSRB6
.long 0x00000030 //MRSRB7
这个时候编译是通过的，但是在烧写到板子上会发现串口乱码，只是因为串口波特率的设置的原因
修改串口波特率
arch/arm/cpu/arm920t/s3c24x0/speed.c get_HCLK 函数中 没有定义CONFIG_S3C2440
在configs/smdk2440.h中定义 #define CONFIG_S3C2440
这个时候编译会提示nand错误
s3c2410_nand.c:87: error: dereferencing pointer to incomplete type
s3c2410_nand.c: In function 'board_nand_init':
s3c2410_nand.c:129: warning: initialization makes pointer from integer without a cast
s3c2410_nand.c:150: error: dereferencing pointer to incomplete type
s3c2410_nand.c:153: error: dereferencing pointer to incomplete type
s3c2410_nand.c:154: error: dereferencing pointer to incomplete type
为了先演示前面的修改情况，先屏蔽这一段，在configs/smdk2440.h中注释掉
#define CONFIG_CMD_BSP
#define CONFIG_CMD_CACHE
#define CONFIG_CMD_DATE
#define CONFIG_CMD_DHCP
#define CONFIG_CMD_ELF
//#define CONFIG_CMD_NAND
#define CONFIG_CMD_PING
#define CONFIG_CMD_REGINFO
#define CONFIG_CMD_USB
然后重新make会出现 "nand_info" 错误
fs/yaffs2/libyaffs2.o: In function `yaffs_StartUp':
/home/book/Par_Uboot/mk_uboot/u-boot-2012.04.01/fs/yaffs2/yaffscfg.c:210: undefined reference to `nand_info'
Makefile:472: recipe for target 'u-boot' failed
make: *** [u-boot] Error 1
这个时候再将#define CONFIG_YAFFS2注释掉，然后先make distclean 再重新上传配置和编译
/*
* File system
*/
#define CONFIG_CMD_FAT
#define CONFIG_CMD_EXT2
#define CONFIG_CMD_UBI
#define CONFIG_CMD_UBIFS
#define CONFIG_CMD_MTDPARTS
#define CONFIG_MTD_DEVICE
#define CONFIG_MTD_PARTITIONS
//#define CONFIG_YAFFS2
#define CONFIG_RBTREE
重新编译通过之后，通过uboot烧写板子上测试
usb 1 30000000 打开dnw下载自己编译好的uboot.bin
protect off all 去除写保护
erase 0 7ffff 擦除512k的内容
cp.b 30000000 0 80000 在30000000烧写512k的内容
重新上电就可以看到正确的输出了
U-Boot 2012.04.01 (Sep 20 2019 - 15:32:58)
CPUID: 32440001
FCLK: 400 MHz
HCLK: 100 MHz
PCLK: 50 MHz
DRAM: 64 MiB
WARNING: Caches not enabled
Flash: *** failed ***
### ERROR ### Please RESET the board ###