ARM嵌入式LINUX设备驱动设计入门学习

        在这里我用的板子是micro2440板子，板子上的linux版本是2.6.13。因为我在前一篇介绍了驱动编程的两种框架设计，所以现在我就来分别写一下这两种框架设计的程序。

开发平台：RED HAT LINUX 9（Linux 2.4.18）

开发板：micro2440（友善之臂）（Linux 2.6.13)

交叉编译工具：arm-linux-gcc-3.4.1

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2.4内核驱动框架：

static int __init leds_init(void)
{
 int result;
 int i;

 result = register_chrdev(LED_MAJOR, DEVICE_NAME, &leds_fops);
 if(result < 0){
  printk(DEVICE_NAME "can't register major number/n");
  return result;
 }
 
// static devfs_handle_t devfs_handle;
// devfs_handle = devfs_register(NULL, DEVICE_NAME, DEVFS_FL_DEFAULT, LED_MAJOR, &leds_fops, NULL);

/*

*之所以不用devfs_register，而用devfs_mk_cdev，原因是因为在linux2.6内核里没有devfs_register函数，而改用*devfs_mk_cdev

*/
 devfs_mk_cdev(MKDEV(LED_MAJOR, 0), S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP, DEVICE_NAME);

 for(i = 0; i < 4; i++){
  s3c2410_gpio_cfgpin(led_table[i], led_cfg_table[i]);
  s3c2410_gpio_setpin(led_table[i], 1);
 }

 printk(DEVICE_NAME "initialized/n");
 return 0;
}

static void __exit leds_exit(void)
{
 devfs_remove(DEVICE_NAME);
 unregister_chrdev(LED_MAJOR, DEVICE_NAME);
}

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2.6内核驱动框架：

static int __init leds_init(void)
{
 int result;
 int i;
 dev_t dev = 0;

 dev = MKDEV(LED_MAJOR, 0);
 result = register_chrdev_region(dev, 1, DEVICE_NAME);
 if (result < 0) 
 {
  printk(KERN_WARNING "DEMO: can't get major %d/n", LED_MAJOR);
  return result;
 }
 
 LED_devices = kmalloc(sizeof(struct DEMO_dev), GFP_KERNEL);
 if (!LED_devices)
 {
  result = -ENOMEM;
  goto fail;
 }
 memset(LED_devices, 0, sizeof(struct DEMO_dev));

 cdev_init(&LED_devices->cdev, &leds_fops);
 LED_devices->cdev.owner = THIS_MODULE;
 LED_devices->cdev.ops = &leds_fops;
 result = cdev_add (&LED_devices->cdev, dev, 1);
 if(result)
 {
  printk(KERN_NOTICE "Error %d adding DEMO/n", result);
  goto fail;
 }
 devfs_mk_cdev(MKDEV(LED_MAJOR, 0), S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP, DEVICE_NAME);

 for(i = 0; i < 4; i++){
  s3c2410_gpio_cfgpin(led_table[i], led_cfg_table[i]);
  s3c2410_gpio_setpin(led_table[i], 1);
 }

 printk(DEVICE_NAME "initialized/n");
  return 0;
fail:
 leds_exit();
 return result;

}

static void __exit leds_exit(void)
{
 dev_t devno = MKDEV(LED_MAJOR, 0);

 if (LED_devices) 
 {
  devfs_remove(DEVICE_NAME);
  cdev_del(&LED_devices->cdev);
  kfree(LED_devices);
 }

 unregister_chrdev_region(devno,1);
}

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在这里我事先都写好了文件才做结构体，和操作函数ioctl，下面我就来介绍介绍

static int leds_ioctl(
 struct inode *inode,
 struct file *file,
 unsigned int cmd,
 unsigned long arg)
{
 switch(cmd){
 case 0:
 case 1:
  if(arg > 4){
   return -EINVAL;
  }
  s3c2410_gpio_setpin(led_table[arg], !cmd);
  return 0;
 default:
  return -EINVAL;
 }
}