2018年10月14日 | Tiny4412的Uart操作

#include "regs.h"

void enable_mmu(unsigned long ttb);

void init_ttb(unsigned long *ttb_base);

void mmap(unsigned long *ttb_base, unsigned long va, unsigned long pa);

void memset(char *buf, char ch, int size);

void memcpy(char *dst, char *src, int size);

void do_irq(unsigned long regs[]);

void uart3_putc(unsigned char ch);

unsigned char uart3_getc(void);

void uart3_puts(char *s);

void uart3_gets(unsigned char *s);

void (*printf)(char *, ...) = 0x43e11434;

void main(void)

{    

    init_uart();

    uart3_puts("\n------------welcome--------------\n");

    while(1) {    

        unsigned char cmd[512];

        uart3_puts("[ Li Baizhang @Yogurt]# ");

        uart3_gets(cmd);

        uart3_puts(cmd);

        uart3_puts("is not supported.\n");

    }

}

void init_uart(void)

{

    //配置引脚

    GPA1CON     &= ~(0xff << 16);    

    GPA1CON  |=  (0x22 << 16);

    //SCLK_user_t == 800M

    //DIVuart3 = 7

    //SCLKuart3 = 800 / (7 + 1) == 100M

    ULCON3 = 3 ; //8N1

    UCON3 = 1 | ( 1 << 2); //接收和发送都设为1:中断或者轮询模式

    UFCON3 = 0;  //禁用FIFO

    // 54.25 - 1 = 53.3

    UBRDIV3 = 0x35;

    UFRACVAL3 = 0x4;    

}

void uart3_putc(unsigned char ch)

{

    while(!(UTRSTAT3 & ( 1 << 1)));

    UTXH3 = ch;

}

unsigned char uart3_getc(void)

{

    unsigned char ch;

    while(!(UTRSTAT3 & ( 1 << 0)));

    ch = URXH3;

    return ch;

}

void uart3_puts(char *s)

{

    while(*s) {

        uart3_putc(*s);

        if (*s == '\n') {

            uart3_putc('\r');

        }

        s ++;

    }

}

void uart3_gets(unsigned char *s)

{

    unsigned char ch = 0;

    while(1) {

        ch = uart3_getc();

        uart3_putc(ch);

        if ((ch == '\r')) {

            uart3_putc('\n');

            break;

        }

        *s = ch;

        s ++;

    }

    *s = 0;

}

void do_irq(unsigned long regs[])

{

    printf("PWM Timer0: Time Out\n");

    TINT_CSTAT |= (1 << 5);

}

void enable_mmu(unsigned long ttb)

{    

    unsigned long c1_flags;

    init_ttb(ttb);

    c1_flags = 1 | (1 << 3) | ( 1 << 11) | ( 1 << 13) |  (1 << 28);

    __asm__ __volatile__ (

        "mvn r0, #0 \n"            

        "mcr p15, 0, r0, c3, c0, 0\n"

        "mcr p15, 0, %1, c2, c0, 0\n" //configure ttb

        "mrc p15, 0, r0, c1, c0, 0\n"

        "orr %0, r0, %0\n"

        "mcr p15, 0, %0, c1, c0, 0\n" //enable mmu

        :

        : "r" (c1_flags), "r" (ttb)

        : "r0"

    );

}

void init_ttb(unsigned long *ttb_base)

{

    unsigned long va, pa;

    for (va = 0x00000000; va < 0x10000000; va += 0x100000) { //Others

        pa = va;

        ttb_base[ va >> 20] = (pa & 0xfff00000) | 2;    

    }

    for (va = 0x10000000; va < 0x14000000; va += 0x100000) { //SFR

        pa = va;

        ttb_base[ va >> 20] = (pa & 0xfff00000) |  2;    

    }

    for (va = 0x40000000; va < 0x80000000; va += 0x100000) { //DRAM

        pa = va;

        ttb_base[ va >> 20] = (pa & 0xfff00000) | 2;    

    }

}

void mmap(unsigned long *ttb_base, unsigned long va, unsigned long pa)

{

    ttb_base[ va >> 20] = (pa & 0xfff00000) |  2;    

}

void memset(char *buf, char ch, int size)

{

    int i;

    for (i = 0; i < size; i ++)

        buf[i] = ch;

}

void memcpy(char *dst, char *src, int size)

{

    int i;

    for (i = 0; i < size; i ++) 

        dst[i] = src[i];    

}

__asm__ (

"vectors:\n"

    "b reset\n"

    "b und\n"

    "b swi\n"

    "b pre_abt\n"

    "b dat_abt\n"

    ".word 0\n"

    "b irq\n"

    "b fiq\n"

"reset:\n"

"und:\n"

    "mov sp, #0x74000000\n"

    "stmfd sp!, {r0-r12, lr}\n"

    "mov r0, sp\n"

    "mov r3, #0x74000000\n"

    "ldr r3, [r3]\n"

    "blx r3\n"

    "mov sp, #0x74000000\n"

    "ldmea sp, {r0-r12, pc}^\n"

"swi:\n"

"pre_abt:\n"

"dat_abt:\n"

"fiq:\n"

"irq:\n"

    "mov sp, #0x75000000\n"

    "sub lr, lr, #4    \n"

    "stmfd sp!, {r0-r12, lr}\n"

    "mov r0, sp\n"

    "mov r3, #0x75000000\n"

    "ldr r3, [r3]\n"

    "blx r3\n"

    "mov sp, #0x75000000\n"

    "ldmea sp, {r0-r12, pc}^\n"

"EOV:\n"

"vectors_start:\n"

    ".word vectors\n"

"vectors_end:\n"

    ".word EOV\n"

);

===================================================================

Makefile文件：

default:

    arm-linux-gcc -c test.c  -o test.o

    arm-linux-ld  -Ttext=0x70003000  test.o  -o test

    arm-linux-objcopy  -O binary  test  test.bin

clean:

    rm -f test.o  test  test.bin   *~ 

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