Linux驱动开发之按键驱动程序

1、平台设备

#include <linux/module.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <asm/arch/regs-gpio.h>
#include <linux/interrupt.h>
#include <linux/device.h>
#include <linux/io.h>

/*平台资源的定义*/
static struct resource s3c_buttons_resource[] = {
[0]={
.start = S3C24XX_PA_GPIO,
.end   = S3C24XX_PA_GPIO + S3C24XX_SZ_GPIO - 1,
.flags = IORESOURCE_MEM,       //IO内存
},

[1]={
.start = IRQ_EINT0,       //注册外部中断0的中断号     
.end   = IRQ_EINT0,
.flags = IORESOURCE_IRQ,
},
[2]={
.start = IRQ_EINT2,        //注册外部中断2的中断号
.end   = IRQ_EINT2,
.flags = IORESOURCE_IRQ,
},
[3]={
.start = IRQ_EINT11,       //注册外部中断11的中断号
.end   = IRQ_EINT11,
.flags = IORESOURCE_IRQ,
},
[4]={
.start = IRQ_EINT19,        //注册外部中断19的中断号
.end   = IRQ_EINT19,
.flags = IORESOURCE_IRQ,
}

};

static struct platform_device s3c_buttons = {
.name = "s3c2440-buttons",   //设备的名称
.id = 0,                   
.num_resources = ARRAY_SIZE(s3c_buttons_resource),  //资源数量
.resource =  s3c_buttons_resource,   //注册到内核中的资源
 };

static int __init platform_init(void)
{

    /*平台设备的注册*/
    platform_device_register(&s3c_buttons);
    return 0;
}


static void __exit platform_exit(void)
{
    platform_device_unregister(&s3c_buttons);  //注销设备
}

module_init(platform_init);
module_exit(platform_exit);

MODULE_LICENSE("GPL");

MODULE_ALIAS("platform:s3c2440buttons");

2、平台驱动

#include <linux/module.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/interrupt.h>
#include <linux/clk.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <asm/arch/regs-gpio.h>
#include <linux/poll.h>
#include <linux/irq.h>
#include <asm/unistd.h>
#include <linux/device.h>

static DECLARE_WAIT_QUEUE_HEAD(button_waitq);

static volatile int ev_press = 0;

static int key_value;
static struct device     *buttons_dev; /* platform device attached to */
static struct resource *buttons_mem;
static struct resource   *buttons_irq;
static void __iomem    *buttons_base;

static int button_irqs[4];

//中断处理函数
static irqreturn_t buttons_interrupt(int irq, void *dev_id)
{
int i;
for(i=0; i<4; i++){
if(irq == button_irqs[i]){
//printk("==>interrput number:%d\n",irq);  
key_value = i; //根据中断号获得键值
ev_press =1;  //标志位置1
wake_up_interruptible(&button_waitq);//在中断里面把读进程唤醒
}
}

    return IRQ_RETVAL(IRQ_HANDLED);

}

static int s3c24xx_buttons_open(struct inode *inode, struct file *file)
{
int i;
int err = 0;
/*注册中断*/
for(i=0; i<4; i++){
if (button_irqs[i] < 0) 
continue;
   
                  /*中断触发方式：上升沿触发*/
        err = request_irq(button_irqs[i],buttons_interrupt,IRQ_TYPE_EDGE_RISING,NULL,NULL);
if(err)
 break;
}

if (err) {
i--;
for (; i >= 0; i--) {
if (button_irqs[i] < 0) {
continue;
}
disable_irq(button_irqs[i]);
free_irq(button_irqs[i], NULL);
}
return -EBUSY;
}

    ev_press = 0;   
    return 0;
}

static int s3c24xx_buttons_close(struct inode *inode, struct file *file)
{
    int i;    
    for (i=0; i<4; i++) {
if (button_irqs[i] < 0) {
continue;
}
free_irq(button_irqs[i],NULL); //注销中断
    }
    return 0;
}

static int s3c24xx_buttons_read(struct file *filp, char __user *buff, size_t count, loff_t *offp)
{
    unsigned long err;
    if (!ev_press) {
if (filp->f_flags & O_NONBLOCK)  //判断是否是非阻塞读
return -EAGAIN;
else
wait_event_interruptible(button_waitq, ev_press);//阻塞读
    }    
    ev_press = 0; //把标志位清零
    err = copy_to_user(buff, &key_value, sizeof(key_value));//把键值传给用户
    return sizeof(key_value);
}

static unsigned int s3c24xx_buttons_poll( struct file *file, struct poll_table_struct *wait)
{
    unsigned int mask = 0;
    poll_wait(file, &button_waitq, wait);//把等待队列添加到poll_table_struct
    if (ev_press){   //标志位，中断控制的
        mask |= POLLIN | POLLRDNORM;
}
    return mask;
}

static struct file_operations s3c2440buttons_fops = {
    .owner   =   THIS_MODULE,
    .open    =   s3c24xx_buttons_open,
    .release =   s3c24xx_buttons_close,
    .read    =   s3c24xx_buttons_read,
    .poll    =   s3c24xx_buttons_poll,
};

static struct miscdevice s3c2440_miscdev = {

    .minor = MISC_DYNAMIC_MINOR, //自动分配混杂设备的次设备号
    .name ="buttons",            //设备名字
    .fops = &s3c2440buttons_fops,
};


/* device interface */
static int s3c2440_buttons_probe(struct platform_device *pdev)
{
struct resource *res;
struct device *dev;
int ret;
int size;
int i;

printk("probe:%s\n", __func__);
dev = &pdev->dev;
buttons_dev = &pdev->dev;

/*平台资源获取*/
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);//获得平台设备注册的IO内存资源
if (res == NULL) {
dev_err(dev, "no memory resource specified\n");
return -ENOENT;
}

size = (res->end - res->start) + 1;  //计算IO内存资源的大小
buttons_mem = request_mem_region(res->start, size, pdev->name);//申请IO内存资源
if (buttons_mem == NULL) {
dev_err(dev, "failed to get memory region\n");
ret = -ENOENT;
goto err_req;
}

buttons_base = ioremap(res->start, size);//把物理地址映射为虚拟地址 返回值为虚拟地址
if (buttons_base == NULL) {
dev_err(dev, "failed to ioremap() region\n");
ret = -EINVAL;
goto err_req;
}
printk(KERN_DEBUG"probe: mapped buttons_base=%p\n", buttons_base);


 /*get irq number*/
  for(i=0; i<4; i++){                  //获取中断号
buttons_irq = platform_get_resource(pdev,IORESOURCE_IRQ,i);//获得平台设备注册的中断资源
if(buttons_irq == NULL){
  dev_err(dev,"no irq resource specified\n");
 ret = -ENOENT;
 goto err_map;
}
button_irqs[i] = buttons_irq->start; //中断资源里面获得中断号
//printk("button_irqs[%d]=%d\n",i,button_irqs[i]);  
}
ret = misc_register(&s3c2440_miscdev);  //注册混杂设备

return 0;


 err_map:
iounmap(buttons_base); //解除映射

 err_req:
release_resource(buttons_mem);
kfree(buttons_mem);


return ret;
}


static int s3c2440_buttons_remove(struct platform_device *dev)//平台驱动移除的时候调用
{
iounmap(buttons_base);  //解除映射
misc_deregister(&s3c2440_miscdev); //注销混杂设备
release_resource(buttons_mem); //注销资源
kfree(buttons_mem);
buttons_mem = NULL;


return 0;
}


/*平台驱动定义*/
static struct platform_driver s3c2440buttons_driver = {
.probe = s3c2440_buttons_probe,   //平台设备和驱动匹配的时候调用
.remove = s3c2440_buttons_remove,  //平台驱动移除的时候调用
.driver = {
.owner = THIS_MODULE,
.name = "s3c2440-buttons",    //平台驱动的名称
},
};


static char banner[] __initdata =
"s3c2440 Buttons Driver\n";


static int __init buttons_init(void)
{
printk(banner);
/*平台驱动注册*/
platform_driver_register(&s3c2440buttons_driver);
return 0;
}


static void __exit buttons_exit(void)
{
platform_driver_unregister(&s3c2440buttons_driver);
}


module_init(buttons_init);
module_exit(buttons_exit);


MODULE_DESCRIPTION("s3c2440 Buttons Driver");

MODULE_LICENSE("GPL");

3、应用程序

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/select.h>
#include <sys/time.h>
#include <errno.h>

int main(void)
{
int buttons_fd=0;
int key_value;

buttons_fd = open("dev/buttons",O_RDWR);//打开设备文件
if (buttons_fd < 0) {
perror("open device buttons");
exit(1);
}

for (;;) {
fd_set rds;  //读文件描述符集
int ret;


FD_ZERO(&rds);  //清空读文件描述符集
FD_SET(buttons_fd, &rds); //把读文件描述符添加到文件描述符集

ret = select(buttons_fd + 1, &rds, NULL, NULL, NULL);//条件不满足阻塞
if (ret < 0) {
perror("select");
exit(1);
}
if (ret == 0) {
printf("Timeout.\n");
} else if (FD_ISSET(buttons_fd, &rds)) {//判断文件是否可读
int ret = read(buttons_fd, &key_value, sizeof(key_value));
if (ret != sizeof(key_value)) {
if (errno != EAGAIN)
perror("read buttons\n");
continue;
} else {
printf("buttons_value: %d\n", key_value+1);
}

}
}

close(buttons_fd);
return 0;
}