// s3c24xx.h // 2015.11.9 /* WOTCH DOG register */ #define WTCON (*(volatile unsigned long *)0x53000000) /* SDRAM regisers */ #define MEM_CTL_BASE 0x48000000 #define SDRAM_BASE 0x30000000 /* NAND Flash registers */ #define NFCONF (*(volatile unsigned int *)0x4e000000) #define NFCMD (*(volatile unsigned char *)0x4e000004) #define NFADDR (*(volatile unsigned char *)0x4e000008) #define NFDATA (*(volatile unsigned char *)0x4e00000c) #define NFSTAT (*(volatile unsigned char *)0x4e000010) /*GPIO registers*/ #define GPBCON (*(volatile unsigned long *)0x56000010) #define GPBDAT (*(volatile unsigned long *)0x56000014) #define GPFCON (*(volatile unsigned long *)0x56000050) #define GPFDAT (*(volatile unsigned long *)0x56000054) #define GPFUP (*(volatile unsigned long *)0x56000058) #define GPGCON (*(volatile unsigned long *)0x56000060) #define GPGDAT (*(volatile unsigned long *)0x56000064) #define GPGUP (*(volatile unsigned long *)0x56000068) #define GPHCON (*(volatile unsigned long *)0x56000070) #define GPHDAT (*(volatile unsigned long *)0x56000074) #define GPHUP (*(volatile unsigned long *)0x56000078) /*UART registers*/ #define ULCON0 (*(volatile unsigned long *)0x50000000) #define UCON0 (*(volatile unsigned long *)0x50000004) #define UFCON0 (*(volatile unsigned long *)0x50000008) #define UMCON0 (*(volatile unsigned long *)0x5000000c) #define UTRSTAT0 (*(volatile unsigned long *)0x50000010) #define UTXH0 (*(volatile unsigned char *)0x50000020) #define URXH0 (*(volatile unsigned char *)0x50000024) #define UBRDIV0 (*(volatile unsigned long *)0x50000028) /*interrupt registes*/ #define SRCPND (*(volatile unsigned long *)0x4A000000) #define INTMOD (*(volatile unsigned long *)0x4A000004) #define INTMSK (*(volatile unsigned long *)0x4A000008) #define PRIORITY (*(volatile unsigned long *)0x4A00000c) #define INTPND (*(volatile unsigned long *)0x4A000010) #define INTOFFSET (*(volatile unsigned long *)0x4A000014) #define SUBSRCPND (*(volatile unsigned long *)0x4A000018) #define INTSUBMSK (*(volatile unsigned long *)0x4A00001c) /*external interrupt registers*/ #define EINTMASK (*(volatile unsigned long *)0x560000a4) #define EINTPEND (*(volatile unsigned long *)0x560000a8) /*clock registers*/ #define LOCKTIME (*(volatile unsigned long *)0x4c000000) #define MPLLCON (*(volatile unsigned long *)0x4c000004) #define UPLLCON (*(volatile unsigned long *)0x4c000008) #define CLKCON (*(volatile unsigned long *)0x4c00000c) #define CLKSLOW (*(volatile unsigned long *)0x4c000010) #define CLKDIVN (*(volatile unsigned long *)0x4c000014) /*PWM & Timer registers*/ #define TCFG0 (*(volatile unsigned long *)0x51000000) #define TCFG1 (*(volatile unsigned long *)0x51000004) #define TCON (*(volatile unsigned long *)0x51000008) #define TCNTB0 (*(volatile unsigned long *)0x5100000c) #define TCMPB0 (*(volatile unsigned long *)0x51000010) #define TCNTO0 (*(volatile unsigned long *)0x51000014) #define GSTATUS1 (*(volatile unsigned long *)0x560000B0)
@******************************************************************************
@ head.S
@ 设置SDRAM，将程序复制到SDRAM，然后跳到SDRAM继续执行
@ 2015.11.9
@******************************************************************************
.extern main
.text
.global _start
_start:
Reset:
ldr sp, =4096
bl disable_watch_dog
bl clock_init @ 设置MPLL，改变FCLK、HCLK、PCLK
bl memsetup
bl copy_steppingstone_to_sdram
ldr pc, =on_sdram
on_sdram:
ldr sp, =0x34000000
ldr lr, =halt_loop @ 设置返回地址，c程序执行完后pc指针会指向lr中的地址
ldr pc, =main
halt_loop:
b halt_loop
// init.c
// 2015.11.9
#include "s3c24xx.h"
void disable_watch_dog(void);
void clock_init(void);
void memsetup(void);
void copy_steppingstone_to_sdram(void);
/*
* 关闭WATCHDOG，否则CPU会不断重启
*/
void disable_watch_dog(void)
{
WTCON = 0; // 关闭WATCHDOG很简单，往这个寄存器写0即可
}
#define S3C2410_MPLL_200MHZ ((0x5c<<12)|(0x04<<4)|(0x00))
#define S3C2440_MPLL_200MHZ ((0x5c<<12)|(0x01<<4)|(0x02))
/*
* 对于MPLLCON寄存器，[19:12]为MDIV，[9:4]为PDIV，[1:0]为SDIV
* 有如下计算公式：
* S3C2410: MPLL(FCLK) = (m * Fin)/(p * 2^s)
* S3C2410: MPLL(FCLK) = (2 * m * Fin)/(p * 2^s)
* 其中: m = MDIV + 8, p = PDIV + 2, s = SDIV
* 对于本开发板，Fin = 12MHz
* 设置CLKDIVN，令分频比为：FCLK:HCLK:PCLK=1:2:4，
* FCLK=200MHz,HCLK=100MHz,PCLK=50MHz
*/
void clock_init(void)
{
// LOCKTIME = 0x00ffffff; // 使用默认值即可
CLKDIVN = 0x03; // FCLK:HCLK:PCLK=1:2:4, HDIVN=1,PDIVN=1
/* 如果HDIVN非0，CPU的总线模式应该从“fast bus mode”变为“asynchronous bus mode” */
__asm__(
"mrc p15, 0, r1, c1, c0, 0\n" /* 读出控制寄存器 */
"orr r1, r1, #0xc0000000\n" /* 设置为“asynchronous bus mode” */
"mcr p15, 0, r1, c1, c0, 0\n" /* 写入控制寄存器 */
);
/* 判断是S3C2410还是S3C2440 */
if ((GSTATUS1 == 0x32410000) || (GSTATUS1 == 0x32410002))
{
MPLLCON = S3C2410_MPLL_200MHZ; /* 现在，FCLK=200MHz,HCLK=100MHz,PCLK=50MHz */
}
else
{
MPLLCON = S3C2440_MPLL_200MHZ; /* 现在，FCLK=200MHz,HCLK=100MHz,PCLK=50MHz */
}
}
/*
* 设置存储控制器以使用SDRAM
*/
void memsetup(void)
{
volatile unsigned long *p = (volatile unsigned long *)MEM_CTL_BASE;
/* 这个函数之所以这样赋值，而不是像前面的实验(比如mmu实验)那样将配置值
* 写在数组中，是因为要生成”位置无关的代码”，使得这个函数可以在被复制到
* SDRAM之前就可以在steppingstone中运行
*/
/* 存储控制器13个寄存器的值 */
p[0] = 0x22011110; //BWSCON
p[1] = 0x00000700; //BANKCON0
p[2] = 0x00000700; //BANKCON1
p[3] = 0x00000700; //BANKCON2
p[4] = 0x00000700; //BANKCON3
p[5] = 0x00000700; //BANKCON4
p[6] = 0x00000700; //BANKCON5
p[7] = 0x00018005; //BANKCON6
p[8] = 0x00018005; //BANKCON7
/* REFRESH,
* HCLK=12MHz: 0x008C07A3,
* HCLK=100MHz: 0x008C04F4
*/
p[9] = 0x008C04F4;
p[10] = 0x000000B1; //BANKSIZE
p[11] = 0x00000030; //MRSRB6
p[12] = 0x00000030; //MRSRB7
}
void copy_steppingstone_to_sdram(void)
{
unsigned int *pdwSrc = (unsigned int *)0;
unsigned int *pdwDest = (unsigned int *)0x30000000;
while (pdwSrc < (unsigned int *)4096)
{
*pdwDest = *pdwSrc;
pdwDest++;
pdwSrc++;
}
}
// serial.c
// 2015.11.9
#include "s3c24xx.h"
#include "serial.h"
#define TXD0READY (1<<2)
#define RXD0READY (1)
#define PCLK 50000000 // init.c中的clock_init函数设置PCLK为50MHz
#define UART_CLK PCLK // UART0的时钟源设为PCLK
#define UART_BAUD_RATE 115200 // 波特率
#define UART_BRD ((UART_CLK / (UART_BAUD_RATE * 16)) - 1)
// 115200,8N1,无流控
void uart0_init(void)
{
GPHCON |= 0xa0; // GPH2,GPH3用作TXD0,RXD0，分别在位[5:4]，[7:6]，设为10使用该功能
GPHUP = 0x0c; // GPH2,GPH3内部上拉
ULCON0 = 0x03; // 8N1(8个数据位，无较验，1个停止位)
UCON0 = 0x05; // 接收模式选择查询方式，UART时钟源为PCLK
UFCON0 = 0x00; // 不使用FIFO
UMCON0 = 0x00; // 不使用流控
UBRDIV0 = UART_BRD; // 波特率为115200
}
void putc(unsigned char c)
{
// 不断查询UTRSTAT0寄存器的位[2]，为1表示发送完毕
while (!(UTRSTAT0 & TXD0READY));
// 向UTXH0寄存器中写入数据，UART即自动将它发送出去
UTXH0 = c;
}
unsigned char getc(void)
{
// 不断查询UTRSTAT0寄存器的位[1]，为1表示接收缓冲区有数据
while (!(UTRSTAT0 & RXD0READY));
// 直接读取URXH0寄存器，即可获得接收到的数据
return URXH0;
}
int isDigit(unsigned char c)
{
if (c >= ‘0‘ && c <= ‘9‘)
return 1;
else
return 0;
}
int isLetter(unsigned char c)
{
if (c >= ‘a‘ && c <= ‘z‘)
return 1;
else if (c >= ‘A‘ && c <= ‘Z‘)
return 1;
else
return 0;
}
// serial.h // 2015.11.9 void uart0_init(void); void putc(unsigned char c); unsigned char getc(void); int isDigit(unsigned char c); int isLetter(unsigned char c);
// main.c
// 2015.11.9
#include "serial.h"
int main()
{
unsigned char c;
uart0_init(); // 波特率115200，8N1(8个数据位，无校验位，1个停止位)
while(1)
{
// 从串口接收数据后，判断其是否数字或子母，若是则加1后输出
c = getc();
if (isDigit(c) || isLetter(c))
putc(c+1);
}
return 0;
}
/* uart.lds*/
SECTIONS {
. = 0x30000000;
.text : { *(.text) } /*所有文件的代码段链接成一个.text的代码段*/
.rodata ALIGN(4) : {*(.rodata)}
.data ALIGN(4) : { *(.data) }
.bss ALIGN(4) : { *(.bss) *(COMMON) }
}
/*.bss段，链接完后，占用的内存释放，不同于.data段一直占有内存。
.bss这个节包含程序还未初始化的数据，当操作系统装入这个程序时将把这些变量都置为0。
使用.bss比使用.data的优势在于，bss节在编译后不占用磁盘的空间，这样编译、连接生成的代码的尺寸会比较小。
*/
objs := head.o init.o serial.o main.o
uart.bin: $(objs)
arm-linux-ld -Tuart.lds -o uart_elf $^
arm-linux-objcopy -O binary -S uart_elf $@
arm-linux-objdump -D -m arm uart_elf > uart.dis
%.o:%.c
arm-linux-gcc -Wall -O2 -c -o [email protected] $<
%.o:%.S
arm-linux-gcc -Wall -O2 -c -o [email protected] $<
clean:
rm -f uart.bin uart_elf uart.dis *.o
时间： 2024-10-22 01:47:32