uarts裸机程序

硬件平台：JZ2440

实现功能：向串口软件实现输出putchar函数

start.s --> 设置堆栈，关闭看门狗，初始化时钟，初始化sdram

init.c -->初始化函数

uart.c -->初始化串口寄存器

uart.h -->

main.c -->

start.s源码：

.extern main

.text

.global _start

_start:

      ldr sp,=

      bl  watchdog_init

      bl  clock_init

      bl  sdram_init

      bl  copy_steppingstone_to_sdram

      ldr pc,=sdram

sdram:

      ldr sp,=0x34000000

      ldr lr,=main_return

      ldr pc,=main

main_return:

      b main_return

init.c 源码：

//watchdog

#define WTCON      (*(volatile unsigned long *)0x53000000)

//clock

#define LOCKTIME   (*(volatile unsigned long *)0x4c000000)

#define MPLLCON    (*(volatile unsigned long *)0x4c000004)

#define CLKDIVN    (*(volatile unsigned long *)0x4c000014)

//sdram

#define BWSCON     (*(volatile unsigned long *)0x48000000)

#define BANKCON0   (*(volatile unsigned long *)0x48000004)

#define BANKCON1   (*(volatile unsigned long *)0x48000008)

#define BANKCON2   (*(volatile unsigned long *)0x4800000c)

#define BANKCON3   (*(volatile unsigned long *)0x48000010)

#define BANKCON4   (*(volatile unsigned long *)0x48000014)

#define BANKCON5   (*(volatile unsigned long *)0x48000018)

#define BANKCON6   (*(volatile unsigned long *)0x4800001c)

#define BANKCON7   (*(volatile unsigned long *)0x48000020)

#define REFRESH    (*(volatile unsigned long *)0x48000024)

#define BANKSIZE   (*(volatile unsigned long *)0x48000028)

#define MRSRB6     (*(volatile unsigned long *)0x4800002c)

#define MRSRB7     (*(volatile unsigned long *)0x48000030)

void watchdog_init(void)

{

    WTCON=;

}

void clock_init(void)

{

    CLKDIVN=0x03;

    __asm__

    (

    "mrc p15,0,r1,c1,c0,0\n"

    "orr r1,r1,#0xc0000000\n"

    "mcr p15,0,r1,c1,c0,0\n"

    );

       MPLLCON=((0x5c<<)|(0x01<<)|(0x02));

}

void sdram_init(void)

{

    volatile unsigned long *sdram_base=(volatile unsigned long *)0x48000000;

    sdram_base[]  = 0x22011110;

    sdram_base[]  = 0x00000700;

    sdram_base[]  = 0x00000700;

    sdram_base[]  = 0x00000700;

    sdram_base[]  = 0x00000700;

    sdram_base[]  = 0x00000700;

    sdram_base[]  = 0x00000700;

    sdram_base[]  = 0x00018005;

    sdram_base[]  = 0x00018005;

    sdram_base[]  = 0x008C04F4;

    sdram_base[] = 0x000000B1;

    sdram_base[] = 0x00000030;

    sdram_base[] = 0x00000030;     

}

void copy_steppingstone_to_sdram(void)

{

    unsigned int *sour=(unsigned int *)0x00000000;

    unsigned int *dest=(unsigned int *)0x30000000;

    while(sour<=(unsigned int *))

    {

        *dest++=*sour++;

    }

}

uart.c 源码：

//uart

#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  UERSTAT0    (*(volatile unsigned long *)0x50000014)

#define  UTXH0       (*(volatile unsigned char *)0x50000020)

#define  URXH0       (*(volatile unsigned char *)0x50000024)

#define  UBRDIV0     (*(volatile unsigned long *)0x50000028)

//GPH

#define  GPHCON      (*(volatile unsigned long *)0x56000070)

#define  GPHDAT      (*(volatile unsigned long *)0x56000074)

#define  GPHUP       (*(volatile unsigned long *)0x56000078)

void uart0_init(void)

{

    GPHCON|=0xa0;

    GPHUP=0x0c;

    ULCON0=0x03;

    UCON0=0x05;

    UFCON0=0x00;

    UMCON0=0x00;

    UBRDIV0=((/(*))-);

}

unsigned char getc(void)

{

    while(!(UTRSTAT0 & 0x01));

    return URXH0;

}

void putc(unsigned char date)

{

    while(!(UTRSTAT0 & 0x02));

    UTXH0=date;

}

uart.h 源码：

#ifndef _UART_H_

#define _UART_H_ 

void uart0_init(void);

unsigned char getc(void);

void putc(unsigned char date);

#endif

main.c 源码：

#include"uart.h"

int main(void)

{

    uart0_init();

    while()

    putc(getc()+);

    return ;

}

连接脚本uart.lds ：

SECTIONS

{

  . = 0x30000000;

  .text  : {*(.test)}

  .rodata : {*(.rodata)}

  .dtat  : {*(.data)}

  .bss   : {*(.bss) *(COMMON)}

}

Makefile:

objs:= start.o init.o uart.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:%.s

    arm-linux-gcc  -o $@ -c $<

%.o:%.c

    arm-linux-gcc  -o $@ -c $<

clean:

    rm -f *.o *.bin *.dis uart_elf

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