uboot源码之时钟和串口修改

2023-08-09 09:42:40

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:  405.600 MHz
HCLK:  101.400 MHz
PCLK:   50.700 MHz
DRAM:  64 MiB
WARNING: Caches not enabled
Flash: *** failed ***
### ERROR ### Please RESET the board ###

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