OK6410裸机之串口发送中断

start.S源码：

.globl _start

_start:

    // 0 地址 

    b reset                                                 // 复位时,cpu跳到0地址 

    ldr pc, =undefined_instruction         // cpu遇到不能识别的指令时 

    ldr pc, _vector_swi                              // 当执行swi指令时, 进入swi模 式 

    b halt     @ldr    pc, _prefetch_abort // 预取中止异常 

    b halt     @ldr    pc, _data_abort       // 数据访问异常 

    b halt     @ldr    pc, _not_used          // 没用到 

    ldr    pc, _irq                                       // 0x18 中断异常 

    b halt     @ldr    pc, _fiq                     // 快中断异常 

_irq :

    .word vector_irq

_vector_swi:

    .word vector_swi

vector_swi:

    // 1. 保存现场 

    ldr sp, =0x56000000

    stmdb sp!, {r0-r12, lr}  // lr就是swi的下一条指令地址 

    // 2. 处理异常 

    mrs r0, cpsr

    ldr r1, =swi_str

    bl print_cpsr

    // 3. 恢复现场 

    ldmia sp!, {r0-r12, pc}^ // ^表示把spsr恢复到cpsr 

swi_str:

    .word 0x00697773        // swi 

undefined_instruction:

    // 1. 保存现场 

    ldr sp, =0x55000000

    stmdb sp!, {r0-r12, lr}

    // 2. 处理异常 

    mrs r0, cpsr

    ldr r1, =und_str

    bl print_cpsr

    // 3. 恢复现场 

    ldmia sp!, {r0-r12, pc}^  // ^表示把spsr恢复到cpsr 

und_str:

    .word 0x00646e75          // und 

usr_str:

    .word 0x00727375          // usr 

vector_irq:

    // 1. 保存现场 

    ldr sp, =0x54000000

    sub lr, lr, #4

    stmdb sp!, {r0-r12, lr}     // lr就是swi的下一条指令地址 

    // 2. 处理异常 

    bl do_irq

    // 3. 恢复现场 

    ldmia sp!, {r0-r12, pc}^  // ^表示把spsr恢复到cpsr 

reset:

// 硬件相关的设置 

    // Peri port setup 

    ldr r0, =0x70000000

    orr r0, r0, #0x13

    mcr p15,0,r0,c15,c2,4       @ 256M(0x70000000-0x7fffffff)

// 关看门狗 

// 往WTCON(0x7E004000)写0 

    ldr r0, =0x7E004000

    mov r1, #0

    str r1, [r0]

    // 设置栈 

    ldr sp, =8*1024

    // 设置时钟 

    bl clock_init

    bl ddr_init

    bl init_uart

    //把片内内存中程序的代码段、数据段复制到它的链接地址去   

    adr r0, _start            // 获得_start指令当前所在的地址 : 0

    ldr r1, =_start           // _start的链接地址 0x51000000 

    ldr r2, =bss_start      // bss段的起始链接地址 

    sub r2, r2, r1

    cmp r0,r1

    beq clean_bss

    bl copy2ddr

    cmp r0, #0

    bne halt

// 清BSS 

// 把BSS段对应的内存清零 

clean_bss:

    ldr r0, =bss_start

    ldr r1, =bss_end

    mov r3, #0

    cmp r0, r1

    ldreq pc, =on_ddr

clean_loop:

    str r3, [r0], #4

    cmp r0, r1    

    bne clean_loop        

    ldr pc, =on_ddr

on_ddr:    

    bl irq_init

    mrs r0, cpsr

    bic    r0,r0,#0x9f  // 清cpsr的I位,M4~M0 

    orr    r0,r0,#0x10

    msr    cpsr,r0       // 进入user mode 

    ldr sp, =0x57000000

    ldr r1, =usr_str

    bl print_cpsr

    swi 0

    // cpu进入svc模式

    // 把之前的cpsr保存到spsr_svc 

    // 切换到r13_svc, r14_svc

    // 把swi的下一条指令存到r14(lr)_svc

    // 跳到地址8

    bl hello

undef:

    .word 0xff000000

    // cpu进入Undefined模式

    // 把之前的cpsr保存到spsr_und 

    // 切换到r13_und, r14_und

    // 把下一条指令存到r14(lr)_und

    // 跳到地址4               

swi_ret:

    bl main

halt:

    b halt    

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

irq.c源码：

#define GPNCON     (*((volatile unsigned long *)0x7F008830))

#define GPNDAT     (*((volatile unsigned long *)0x7F008834))

#define EINT0CON0  (*((volatile unsigned long *)0x7F008900))

#define EINT0MASK  (*((volatile unsigned long *)0x7F008920))

#define EINT0PEND  (*((volatile unsigned long *)0x7F008924))

#define PRIORITY    (*((volatile unsigned long *)0x7F008280))

#define SERVICE     (*((volatile unsigned long *)0x7F008284))

#define SERVICEPEND (*((volatile unsigned long *)0x7F008288))

#define VIC0IRQSTATUS  (*((volatile unsigned long *)0x71200000))

#define VIC0FIQSTATUS  (*((volatile unsigned long *)0x71200004))

#define VIC0RAWINTR    (*((volatile unsigned long *)0x71200008))

#define VIC0INTSELECT  (*((volatile unsigned long *)0x7120000c))

#define VIC0INTENABLE  (*((volatile unsigned long *)0x71200010))

#define VIC0INTENCLEAR (*((volatile unsigned long *)0x71200014))

#define VIC0PROTECTION (*((volatile unsigned long *)0x71200020))

#define VIC0SWPRIORITYMASK (*((volatile unsigned long *)0x71200024))

#define VIC0PRIORITYDAISY  (*((volatile unsigned long *)0x71200028))

#define VIC0VECTADDR0      (*((volatile unsigned long *)0x71200100))

#define VIC0VECTADDR1      (*((volatile unsigned long *)0x71200104))

#define VIC0ADDRESS        (*((volatile unsigned long *)0x71200f00))

#define VIC1IRQSTATUS      (*((volatile unsigned long *)0x71300000))

#define VIC1VECTADDR5      (*((volatile unsigned long *)0x71300114))

#define VIC1INTENABLE      (*((volatile unsigned long *)0x71300010))

#define VIC1ADDRESS        (*((volatile unsigned long *)0x71300f00))

void eint0_3_irq(void)

{

    int i;

    printf("eint0_3_irq\n\r");  // K1~K4 

    for (i = 0; i < 4; i ++)

    {

        if (EINT0PEND & (1<

        {

            if (GPNDAT & (1<

            {

                printf("K%d released\n\r", i+1);

            }

            else

            {

                printf("K%d pressed\n\r", i+1);

            }

        }

    }

}

void eint4_11_irq(void)

{

    int i;

    printf("eint4_11_irq\n\r"); // K5~K6 

    for (i = 4; i < 6; i ++)

    {

        if (EINT0PEND & (1<

        {

            if (GPNDAT & (1<

            {

                printf("K%d released\n\r", i+1);

            }

            else

            {

                printf("K%d pressed\n\r", i+1);

            }

        }

    }

}

void irq_init(void)

{

    key_irq_init();

    uart_irq_init();

}

void uart_irq(void)

{

    // 调用具体的中断处理函数 

    do_uart_irq();

    // 清中断 

    VIC1ADDRESS = 0;

}

void uart_irq_init(void)

{

    VIC1INTENABLE |= (1<<5); // bit5: int_uart0  

    VIC1VECTADDR5 = uart_irq;

}

void key_irq_init(void)

{

    // 配置GPIO引脚为中断引脚 

    // GPN0~5 设为中断引脚 

    GPNCON &= ~(0xfff);

    GPNCON |= 0xaaa;

    // 设置中断触发方式为: 双边沿触发 

    EINT0CON0 &= ~(0xfff);

    EINT0CON0 |= 0x777;

    // 使能中断 

    EINT0MASK &= ~(0x3f);

    // 在中断控制器里使能这些中断 

    VIC0INTENABLE |= (0x3); // bit0: eint0~3, bit1: eint4~11  

    VIC0VECTADDR0 = eint0_3_irq;

    VIC0VECTADDR1 = eint4_11_irq;

    // 设置优先级 

}

void do_irq(void)

{

    int i = 0;

    void (*the_isr)(void);

    if (VIC0IRQSTATUS)

    {

        the_isr = VIC0ADDRESS;

        // 2.1 分辨是哪个中断 

        // 2.2 调用它的处理函数     

        // 2.3 清中断     

        the_isr();

        EINT0PEND   = 0x3f;  // 清中断 

        VIC0ADDRESS = 0;

    }

    else if (VIC1IRQSTATUS)

    {

        the_isr = VIC1ADDRESS;

        // 2.1 分辨是哪个中断 

        // 2.2 调用它的处理函数     

        // 2.3 清中断     

        the_isr();

    }

}

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

uart.c源码：

#define ULCON0     (*((volatile unsigned long *)0x7F005000))

#define UCON0      (*((volatile unsigned long *)0x7F005004))

#define UFCON0     (*((volatile unsigned long *)0x7F005008))

#define UMCON0     (*((volatile unsigned long *)0x7F00500C))

#define UTRSTAT0   (*((volatile unsigned long *)0x7F005010))

#define UFSTAT0    (*((volatile unsigned long *)0x7F005018))

#define UTXH0      (*((volatile unsigned char *)0x7F005020))

#define URXH0      (*((volatile unsigned char *)0x7F005024))

#define UBRDIV0    (*((volatile unsigned short *)0x7F005028))

#define UDIVSLOT0  (*((volatile unsigned short *)0x7F00502C))

#define UINTP0     (*((volatile unsigned long *)0x7F005030))

#define UINTM0     (*((volatile unsigned long *)0x7F005038))

#define GPACON     (*((volatile unsigned long *)0x7F008000))

#define ENABLE_FIFO 1

static delay(void)

{

    volatile int i = 10;

    while (i--);

}

void uart_tx_int_enable(void)

{

    UINTM0 &= ~(1<<2);    

}

void uart_tx_int_disable(void)

{

    UINTM0 |= (1<<2);    

}

void init_uart(void)

{

    GPACON &= ~0xff;

    GPACON |= 0x22;

    // ULCON0 

    ULCON0 = 0x3;                 // 数据位:8, 无较验, 停止位: 1, 8n1 

    UCON0  = 0x5 | (1<<9);   // 使能UART发送、接收, tx interrupt request type = level 

#ifdef ENABLE_FIFO

    UFCON0 = 0x07 | (1<<6); // FIFO enable, tx fifo trigger level = 16 bytes     

#else

    UFCON0 = 0x00;               // FIFO disable 

#endif

    UMCON0 = 0;

    // 波特率 

    // DIV_VAL = (PCLK / (bps x 16 ) ) - 1 

    // bps = 57600

    // DIV_VAL = (66500000 / (115200 x 16 ) ) - 1 

    //         = 35.08

    UBRDIV0   = 35;

    // x/16 = 0.08

    // x = 1

    UDIVSLOT0 = 0x1;

}

unsigned char getc(void)

{

#ifdef ENABLE_FIFO

    while ((UFSTAT0 & 0x7f) == 0)delay();

#else    

    while ((UTRSTAT0 & (1<<0)) == 0);

#endif

    return URXH0;

}

int getc_nowait(unsigned char *pChar)

{

#ifdef ENABLE_FIFO

    if ((UFSTAT0 & 0x7f) == 0)

#else

    if ((UTRSTAT0 & (1<<0)) == 0)

#endif        

    {

        return -1;

    }

    else

    {    

        *pChar = URXH0;

        return 0;

    }

}

#define TX_BUF_LEN   2048

static unsigned char txbuf[2047];

static unsigned int r_idx = 0;

static unsigned int w_idx = 0;

static int isFull(void)

{

    if ((w_idx + 1) % TX_BUF_LEN == r_idx)

        return 1;

    else

        return 0;

}

static int isEmpty(void)

{

    return (w_idx == r_idx);

}

static int putData(unsigned char data)

{

    if (isFull())

        return -1;

    else

    {

        txbuf[w_idx] = data;

        w_idx = (w_idx + 1) % TX_BUF_LEN;

        return 0;

    }

}

static int getData(unsigned char *pdata)

{

    if (isEmpty())

    {

        return -1;

    }

    else

    {

        *pdata = txbuf[r_idx];

        r_idx = (r_idx + 1) % TX_BUF_LEN;

        return 0;

    }

}

void putc(char c)

{

    putData(c);    // 把数据放到缓冲区里去 

    // 如果"uart 发送中断"未使能的话，使能"uart 发送中断" 

    uart_tx_int_enable();

}

void do_uart_irq(void)

{

    int i;

    int cnt;

    unsigned char c;

    if (UINTP0 & (1<<2))

    {

        // 对于发送中断 

         if (isEmpty())

         {

             // 禁止中断 

            uart_tx_int_disable();

         }

         else

         {

             // 从环型缓冲区里取出数据, 放到TX FIFO里去 

            cnt = (UFSTAT0 >> 8) & 0x3f;

            cnt = 64 - cnt;

            for (i = 0; i < cnt; i++)

            {

                if (getData(&c) == 0)

                {

                    UTXH0 = c;

                }

                else

                {

                    break;

                }

            }

         }

    }

    else if (UINTP0 & (1<<0))

    {

        // 对于接收中断, 从RX FIFO里取出数据 

    }

    // 清中断 

    UINTP0 = 0xf;

}

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

Makefile文件：

CC      = arm-linux-gcc

LD      = arm-linux-ld

AR      = arm-linux-ar

OBJCOPY = arm-linux-objcopy

OBJDUMP = arm-linux-objdump

INCLUDEDIR     := $(shell pwd)/include

CFLAGS             := -Wall -Os -fno-builtin-printf  -fno-builtin-putc   //避免putc函数名冲突

CPPFLAGS        := -nostdinc -I$(INCLUDEDIR)

export     CC AR LD OBJCOPY OBJDUMP INCLUDEDIR CFLAGS CPPFLAGS 

objs := start.o sdram.o nand.o clock.o uart.o irq.o  main.o lib/libc.a

uart.bin: $(objs)

    ${LD} -Tuart.lds -o uart.elf $^

    ${OBJCOPY} -O binary -S uart.elf $@

    ${OBJDUMP} -D uart.elf > uart.dis

.PHONY : lib/libc.a

lib/libc.a:

    cd lib; make; cd ..

%.o:%.c

    ${CC} $(CPPFLAGS) $(CFLAGS) -c -o $@ $<