一个简单按键驱动for mini2440

最近移植了linux内核, 制作了文件系统,于是就写了一个简单key驱动检验一下.

 

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include

#define DEVICE_NAME "mini2440_key"
#define KEY_MAJOR 232

static DECLARE_WAIT_QUEUE_HEAD(key_waitq);

static volatile int ev_press = 0;

static volatile int press_cnt[] = { 0, 0, 0, 0, 0, 0};

struct key_irq_desc {
 unsigned int irq;
 unsigned long flags;
 const char *name;
};

static struct key_irq_desc key_irqs[] = {
 {IRQ_EINT8, IRQT_FALLING, "key1"},
 {IRQ_EINT11, IRQT_FALLING, "key2" },
 {IRQ_EINT13, IRQT_FALLING, "key3"},
 {IRQ_EINT14, IRQT_FALLING, "key4"},
 {IRQ_EINT15, IRQT_FALLING, "key5"},
 {IRQ_EINT19, IRQT_FALLING, "key6"}
};

static irqreturn_t key_interrupt(int irq, void *dev_id)
{
 volatile int *press_cnt = (volatile int *)dev_id;
 
 *press_cnt = *press_cnt + 1;
 ev_press = 1;
 wake_up_interruptible(&key_waitq);
 
 return IRQ_RETVAL(IRQ_HANDLED);
}

 

static int mini2440_key_open(struct inode *inode, struct file *file)
{
 int i;
 int err;
 
 for (i = 0; i < sizeof(key_irqs) / sizeof(key_irqs[0]); i++)
 {
  err = request_irq(key_irqs[i].irq, key_interrupt, key_irqs[i].flags, \
     key_irqs[i].name, (void *)&press_cnt[i]);
  if (err)
  {
   break;
  }
 }
 if (err)
 {
  i--;
  for (; i >= 0; i--)
  {
   free_irq(key_irqs[i].irq, (void *)&press_cnt[i]);
  }
 }

 return 0;
}

static int mini2440_key_release(struct inode *inode, struct file *file)
{
 int i;
 
 for (i = 0; i < sizeof(key_irqs) / sizeof(key_irqs[0]); i++)
 {
  free_irq(key_irqs[i].irq, (void *)&press_cnt[i]);
 }
 return 0;
}

static int mini2440_key_read(struct file *filp, char __user *buff, size_t count, loff_t *offp)
{
 unsigned long err;
 
 wait_event_interruptible(key_waitq, ev_press);
 
 ev_press = 0;
 
 err = copy_to_user(buff, (const void *)press_cnt, min(sizeof(press_cnt), count));
 
 memset((void *)press_cnt, 0, sizeof(press_cnt));
 
 return err ? -EFAULT : 0;
}

static struct file_operations mini2440_key_fops = {
 .owner = THIS_MODULE,
 .open = mini2440_key_open,
 .release = mini2440_key_release,
 .read = mini2440_key_read, 
};

static int __init mini2440_key_init(void)
{
 int ret;

 ret = register_chrdev(KEY_MAJOR, DEVICE_NAME, &mini2440_key_fops);
 if (ret < 0)
 {
  printk(KERN_NOTICE"can not register major number\n");
  return ret;
 }
 printk(KERN_INFO" register sucess\n");
 return 0;
}

static int __exit mini2440_key_exit(void)
{
 unregister_chrdev(KEY_MAJOR, DEVICE_NAME);
 return 0;
}

module_init(mini2440_key_init);
module_exit(mini2440_key_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("more&&high");

insmod mini2440_key.ko

mknod /dev/mini2440_key c 232 0

 

测试程序

./test_key

/home # ./test_key
key 3 has been pressed 1 times!
/home # ./test_key
key 4 has been pressed 1 times!
/home # ./test_key
key 6 has been pressed 1 times!
/home #