linux驱动程序设计实例

AT91SAM9G20驱动程序设计

开发环境：Vmware + ubuntu10.04

硬件平台：AT91SAM9G20

Linux版本：linux2.6.27

一：led驱动

说明：因为设计的开发板上没有led灯，便通过PC0来演示，通过示波器来观察引脚端的电平变化。

1.驱动程序：my_led.c

#include

#include

#include

#include

#include

#include

#include

#define MY_LED_MAJOR 250 //定义主设备号

#define LED_ON 0

#define LED_OFF 1

struct global_dev{

struct cdev cdev;

}; //定义设备结构体

struct global_dev *global_devp; //定义一个指向设备结构体的指针

static int my_led_open(struct inode *inode, struct file *filp)

{

filp->private_data = global_devp;

return 0;

}

static int my_led_release(struct inode *inode, struct file *file)

{

return 0;

}

static int my_led_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long data) {

switch(cmd)

{

case LED_ON:

at91_set_gpio_value(A T91_PIN_PC0, 0); //将PC0引脚置低

break;

case LED_OFF:

at91_set_gpio_value(A T91_PIN_PC0, 1); //将PC1引脚置高

break;

default:

printk("no valid cmd input!\n");

break;

}

return 0;

}

struct file_operations my_led_ctl_ops ={

.owner = THIS_MODULE,

.open = my_led_open,

.release = my_led_release,

.ioctl = my_led_ioctl,

};

/*初始化设备结构体*/

static void my_led_setup(struct global_dev *dev, int index)

{

int err;

int devno = MKDEV(MY_LED_MAJOR, index);

cdev_init(&dev->cdev, &my_led_ctl_ops);

dev->cdev.owner = THIS_MODULE;

dev->cdev.ops = &my_led_ctl_ops;

err = cdev_add(&dev->cdev, devno, 1);

if(err)

printk("add my led setup failed!\n");

}

static int my_led_init(void)

{

int ret;

dev_t devno = MKDEV(MY_LED_MAJOR, 0); //创建设备号

printk("my first driver--led!\n");

at91_set_GPIO_periph(A T91_PIN_PC0, 1);

at91_set_gpio_output(A T91_PIN_PC0, 1); //对PC0引脚的初始化

ret = register_chrdev_region(devno, 1, "my_led"); //申请设备号

if( ret < 0) {

printk("my_led init_module failed with %d\n", ret);

return ret;

}

else

printk("my_led init_module success!\n");

global_devp = kmalloc(sizeof(struct global_dev), GFP_KERNEL); //申请设备内存memset(global_devp, 0, sizeof(struct global_dev));

my_led_setup(global_devp, 0);

return ret;

}

static void my_led_cleanup(void)

{

cdev_del(&global_devp->cdev); //删除设备

kfree(global_devp); //释放内存

unregister_chrdev_region(MKDEV(MY_LED_MAJOR, 0), 1); //释放设备号

}

MODULE_LICENSE("MYGPL");

MODULE_AUTHOR("FANY");

module_init(my_led_init); //注册设备

module_exit(my_led_cleanup); //卸载设备