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linux2.6内核下的一个按键中断驱动程序示例

热度:49   发布时间:2023-12-09 03:25:32.0

 本程序是基于三星s3c2410ARM平台下的按键驱动例程,程序中两个按键分别占用了ARM芯片上的外部中断16和17,程序中设定外部中断为下降沿响应中断.本程序是在2.6.16内核版本下编译测试通过,交叉编译器采用3.4.1版本的arm-linux-gcc.
 
1.驱动程序文件名为button.c,其源码如下示:
/**********************start*******************************/
#i nclude <linux/config.h>
#i nclude <linux/module.h>
#i nclude <linux/version.h>
#i nclude <linux/kernel.h>
#i nclude <linux/init.h>
#i nclude <linux/fs.h>
#i nclude <asm/hardware.h>
#i nclude <asm/delay.h>
#i nclude <asm/uaccess.h>
#i nclude <asm-arm/arch-s3c2410/regs-gpio.h>

#i nclude <asm/io.h>
#i nclude <asm-arm/arch-s3c2410/irqs.h>
#i nclude <asm-arm/irq.h>
#i nclude <linux/interrupt.h>
#i nclude <linux/wait.h>

#define     BUTTON_IRQ1 IRQ_EINT16
#define     BUTTON_IRQ2 IRQ_EINT17
#define DEVICE_NAME "button"
static int buttonMajor=0;
#define     BUTTONMINOR 0
#define     MAX_BUTTON_BUF  16
   
#define BUTTONSTATUS_1      16
#define BUTTONSTATUS_2      17


static unsigned char buttonRead(void);
static int flag=0;

typedef struct {
    unsigned int buttonStatus;      //按键状态
    unsigned char buf[MAX_BUTTON_BUF]; //按键缓冲区
    unsigned int head,tail;         //按键缓冲区头和尾
    wait_queue_head_t wq;           //等待队列
} BUTTON_DEV;

static BUTTON_DEV buttondev;

#define BUF_HEAD    (buttondev.buf[buttondev.head])     //缓冲区头
#define BUF_TAIL    (buttondev.buf[buttondev.tail])     //缓冲区尾
#define INCBUF(x,mod)   ((++(x)) & ((mod)-1))       //移动缓冲区指针

static void (*buttonEvent)(void);

static void buttonEvent_dummy(void) {}

static void buttonEvent_1(void)
{
    if(buttondev.buttonStatus==BUTTONSTATUS_2) {
    BUF_HEAD=BUTTONSTATUS_2;
     }
    else {
    BUF_HEAD=BUTTONSTATUS_1;
     }
    buttondev.head=INCBUF(buttondev.head,MAX_BUTTON_BUF);
    flag=1;
    wake_up_interruptible(&(buttondev.wq));
    printk("buttonEvent_1/n");
}

static irqreturn_t isr_button(int irq,void *dev_id,struct pt_regs *regs)
{
   
    printk("Occured key board Inetrrupt,irq=%d/n",irq-44);
    switch (irq) {
    case BUTTON_IRQ1:buttondev.buttonStatus=BUTTONSTATUS_1;
                break;
    case BUTTON_IRQ2:buttondev.buttonStatus=BUTTONSTATUS_2;
                break;
    default:break;
     }
   
    buttonEvent();
    return 0;
}

static int button_open(struct inode *inode,struct file *filp)
{
    int ret;
    buttondev.head=buttondev.tail=0;
    buttonEvent=buttonEvent_1; 
    ret=request_irq(BUTTON_IRQ1,isr_button,SA_INTERRUPT,DEVICE_NAME,NULL);
    if(ret) {
    printk("BUTTON_IRQ1: could not register interrupt/n");
    return ret;
     }
    ret=request_irq(BUTTON_IRQ2,isr_button,SA_INTERRUPT,DEVICE_NAME,NULL);
    if(ret) {
    printk("BUTTON_IRQ2: could not register interrupt/n");
    return ret;
     }
    return 0;
}

static int button_release(struct inode *inode,struct file *filp)
{
    buttonEvent=buttonEvent_dummy;
    free_irq(BUTTON_IRQ1,NULL);
    free_irq(BUTTON_IRQ2,NULL);
    return 0;
}

static ssize_t button_read(struct file *filp,char *buffer,size_t count,loff_t *ppos)
{
    static unsigned char button_ret;
 retry:
    printk("retry start/n");
    if(buttondev.head!=buttondev.tail) {
    button_ret=buttonRead();
    copy_to_user(buffer,(char *)&button_ret,sizeof(unsigned char));
    printk("the button_ret is 0x%x/n",button_ret);
    return sizeof(unsigned char);
     }
    else {
    if(filp->f_flags & O_NONBLOCK)
        return -EAGAIN;
    printk("sleep/n");
    //interruptible_sleep_on(&(buttondev.wq));//为安全起见,最好不要调用该睡眠函数
    wait_event_interruptible(buttondev.wq,flag);
    flag=0;
    printk("sleep_after/n");
    if(signal_pending(current))
         {
        printk("rturn -ERESTARTSYS/n");
        return -ERESTARTSYS;
          }
    goto retry;
     }

    return sizeof(unsigned char);
}

static struct file_operations button_fops= {
    .owner  =   THIS_MODULE,
    .open   =   button_open,
    .read   =   button_read,
    .release    =   button_release,
};

static int __init s3c2410_button_init(void)
{
    int ret;
    set_irq_type(BUTTON_IRQ1,IRQT_FALLING);
    set_irq_type(BUTTON_IRQ2,IRQT_FALLING);

    buttonEvent=buttonEvent_dummy;
   
    ret=register_chrdev(0,DEVICE_NAME,&button_fops);
    if(ret<0) {
    printk("button: can't get major number/n");
    return ret;
     }
    buttonMajor=ret;
#ifdef  CONFIG_DEVFS_FS
 devfs_mk_cdev(MKDEV(buttonMajor,BUTTONMINOR),S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP,DEVICE_NAME);
#endif
    //buttondev.head=buttondev.tail=0;
    buttondev.buttonStatus=BUTTONSTATUS_1;
    init_waitqueue_head(&(buttondev.wq));
    printk(DEVICE_NAME"initialized/n");
    return 0;
}

static unsigned char buttonRead(void)
{
    unsigned char button_ret;
    button_ret=BUF_TAIL;
    buttondev.tail=INCBUF(buttondev.tail,MAX_BUTTON_BUF);
    return button_ret;
}
   
static void __exit s3c2410_button_eixt(void)
{
 
 #ifdef CONFIG_DEVFS_FS
    devfs_remove(DEVICE_NAME);
   
 #endif
    unregister_chrdev(buttonMajor,DEVICE_NAME);
}

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Kision");
MODULE_DESCRIPTION ("the first char device driver");

module_init(s3c2410_button_init);
module_exit(s3c2410_button_eixt);
/*************************end***************************/  
 
2.   当然在编写2.6内核驱动程序之前应该已经自己建立好一个2.6的内核源码树(我这里是基于s3c2410移植的源码树,本处该源码是放在宿主机的 /home/src/linux-2.6.16目录下的),如果没有的话,那么需要自己去建立好这个源码树.自己编写的模块化驱动程序可以不放在内核源码之内,但是此外还需要一个自己编写一个Makefile文件(该文件和上面的button.c文件应放在同一个目录下),其内容如下示:
 
ifneq ($(KERNELRELEASE),)
    obj-m :=button.o
else
    KERNELDIR ?= /home/src/linux-2.6.16
    PWD := $(shell pwd)
default:
    $(MAKE) -C $(KERNELDIR) M=$(PWD) modules
clean:
    rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions
endif
 
3.在宿主机的终端下,进入驱动程序目录内,敲入命令:
#make
就会在该目录下生成button.ko文件,这就是2.6内核下生成的驱动加载模块,注意是.ko文件,不同于2.4内核下的.o文件.
把该button.ko文件拷贝到目标板上,在minicom终端下进入该文件目录,敲入:
#insmod button.ko
如果终端显示有buttoninitialized则表示加载成功.
这时可以用命令lsmod查看动态加载模块:
#lsmod
当然,可以用如下命令查看devfs文件系统信息:
#cat /proc/devices
如果用卸载该模块,敲入命令:
#rmmod button
 
4.加载驱动程序后,可以自己再编写一个简单的测试程序,如下:
/**************************start***********************/
#i nclude <sys/stat.h>

#i nclude <fcntl.h>

#i nclude <stdio.h>

#i nclude <sys/time.h>

#i nclude <sys/types.h>

#i nclude <unistd.h>
 

 

main()

{

  

   int retval;

   int fileno;

   int ts, maxfd;

   int  ret= 0,i,j;

   int number;

 

   fileno = open("/dev/button",O_RDWR);

       if (fileno == -1) {

               printf("open device led errr!/n");

               return 0;

              }

   while(1) {

   read(fileno,&number,1);
   printf("key=0x%x/n",number);
    }
  

   close(fileno);

   return 0;

 

}
/**************************end***********************/
 
命名为test.c,并交叉编译该文件:
#arm-linux-gcc test.c -o test
将二进制文件同样拷贝到目标板上,运行:
#./test &
即可看到实验效果.

本文来自: (www.91linux.com) 详细出处参考:http://www.91linux.com/html/article/kernel/20071207/8914.html

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