这几天在写了一个按键驱动，在开发板加载后用cat /proc/device 能看到有我加载的驱动，然后用mknod命令在/dev/下添加设备，也成功了，但是用测试程序测试的时候提示是打开设备失败，请大家帮忙看看，附上程序如下（也可下载附件：
keydrv.rar (2 K) 下载次数:5 ），先谢谢大家了。
驱动程序：
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/cdev.h>
dev_t devno;
struct KEY_DEV
{
struct cdev cdev;
};
struct KEY_DEV *g_pkey_dev;
static int key_open(struct inode *inode, struct file *filp)
{
printk(KERN_NOTICE "key opened\n");
return 0;
}
static int key_release(struct inode *inode, struct file *filp)
{
return 0;
}
static ssize_t key_read(struct file *filp, char *buf, size_t count, loff_t *ppos)
{
return 0;
}
static int key_ioctl(struct inode *inodep, struct file *filp, unsigned int cmd, unsigned long arg)
{
return 0;
}
static struct file_operations g_tkey_fops =
{
.owner = THIS_MODULE,
.open = key_open, //打开设备
.release = key_release, //关闭设备
.read = key_read, //读取按键的键值
.ioctl = key_ioctl, //清除缓冲区
};
static int __devinit key_dev_probe(struct device *dev)
{
struct platform_device *pdev;
int err;
if ( dev == NULL )
{
printk(KERN_NOTICE "null device pointer!\n");
return -ENODEV;
}
pdev = to_platform_device(dev);
g_pkey_dev = kcalloc(1, sizeof(struct KEY_DEV), GFP_KERNEL);
if (unlikely(g_pkey_dev == NULL))
{
printk(KERN_NOTICE "Can't allocate memory for device!\n");
return -ENOMEM;
}
memset(g_pkey_dev, 0, sizeof(struct KEY_DEV));
cdev_init(&g_pkey_dev->cdev, &g_tkey_fops);
g_pkey_dev->cdev.owner = THIS_MODULE;
g_pkey_dev->cdev.ops = &g_tkey_fops;
err = cdev_add(&g_pkey_dev->cdev, devno, 1);
if(err)
{
printk(KERN_NOTICE "Error in adding dev");
}
return 0;
}
static int __devexit key_dev_remove(struct device * dev)
{
return 0;
}
static struct device_driver key_driver =
{
.name = "Mini2440_Key",
.bus = &platform_bus_type,
.probe = key_dev_probe,
.remove = key_dev_remove,
.owner = THIS_MODULE,
};
static int mini2440_key_init(void)
{
int ret;
ret = alloc_chrdev_region(&devno, 0, 1,"Mini2440_Key");
if(ret < 0)
{
return ret;
}
ret = driver_register(&key_driver);
if(unlikely(ret))
{
printk(KERN_NOTICE "driver registration failed: %d\n", ret);
return -ret;
}
printk(KERN_NOTICE "Init finish!\n");
return 0;
}
static void key_exit(void)
{
return;
}
MODULE_AUTHOR("Benson");
MODULE_LICENSE("Dual BSD/GPL");
module_init(mini2440_key_init);
module_exit(key_exit);
