《Linux驱动基础篇》- 1.LED灯驱动入门

来源：互联网发布：风撑规格算法编辑：程序博客网时间：2024/05/16 08:32

无操作系统下LED驱动：

#define led_ctrl_reg       LED_CTRL_REG#define led_data_reg     LED_DATA_REG/*初始化LED*/void InitLight() {    led_ctrl_reg  |= 1 << n;}/*点亮LED*/void LightOn() {    led_data_reg  |= 1 << n;}/*熄灭LED*/void LightOff() {    led_data_reg  &= ~(1 << n);}

最后将上述函数提供给应用程序使用

有操作系统下LED驱动：

#include ...  /*包含多个头文件*//*设备结构体*/struct light_dev {    struct cdev cdev;    unsigned char val;            /*LED亮时为1，灭时为0*/}/*Light设备实例、主设备号*/struct light_dev *light_devp;int light_major = LIGHT_MAJOR;struct file_operations light_fops = {    .owner = THIS_MODULE;    .read = light_read;    .write = light_write；    .ioctl = light_ioctl;    .open = light_open;    .release = light_release;}/*模块初始化函数*/static int __init light_init(void) {    dev_t dev = MKDEV(light_major, 0);    /*申请设备号*/             //1.静态申请（主设备号确定）             register_chrdev_region(dev, 1, "LED");             //2.动态申请（分配主设备号）             alloc_chrdev_region(&dev, 0, 1, "LED");             light_major = MAJOR(dev);     /*分配Lihgt设备结构体*/         light_devp = kmalloc(sizeof(struct light_dev), GFP_KERNEL);         memset(light_devp, 0, sizeof(struct light_dev));    /*注册字符设备*/         cdev_init(&dev->cdev, &light_fops);         cdev_add(&dev->cdev, dev ,1);         light_init();         return 0;}       void light_cleanup(void) {    cdev_del(&light_devp->cdev);    kfree(light_devp);    unregister_chrdev_region(MKDEV(light_major, 0), 1);}module_init(light_init);module_exit(light_cleanup);

下面是文件操作的实现：

/*Light设备的打开关闭函数*/int light_open(struct inode *inode, struct file *filp) {    struct light_dev *dev;    dev = container_of(inode->i_cdev, struct light_dev, cdev);    filp->private_data = dev;    return 0;}int light_release(struct inode *inode, struct file *filp) {    return 0;}/*Light设备的读写函数*/ssize_t light_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos) {    struct light_dev *dev  = filp->private_data;    if(copy_to_user(buf, &(dev->val), 1)) {        return -EFAULT;    }    return 1;}ssize_t light_write(struct file *filp, char __user *buf, size_t count, loff_t *f_pos) {    struct light_dev *dev  = filp->private_data;    if(copy_from_user( &(dev->val), buf, 1)) {        return -EFAULT;    }    if(dev->val == 1) {        light_on();    } else {        light_off();    }    return 1;}/*Light设备的控制函数*/int light_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, usigned long arg) {    struct light_dev *dev = filp->private;    switch(cmd) {        case LIGHT_ON:            dev->val = 1;            light_on();            break;       case LIGHT_OFF:           dev-val = 0;           light_off();           break;       default:           return -ENOTTY;            }    return 0;}

代码没有注重细节，而是在重在体现LED字符设备结构

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