练习.
驱动代码：
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/poll.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/gpio.h>
#include <linux/timer.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/interrupt.h>//中断
struct device_node *dnode;
unsigned int key_irqno;
unsigned int gpiono;
//字符设备驱动
int major;
//自动创建设备节点
struct class *cls;
struct device *dev; int number = 0;
unsigned int condition = 0;
wait_queue_head_t wq_head; //等待队列头// 封装操作方法
int mycdev_open(struct inode *inode, struct file *file)
{printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);return 0;
}
ssize_t mycdev_read(struct file *file, char *ubuf, size_t size, loff_t *lof)
{char kbuf[128] = {0};sprintf(kbuf, "number = %d", number);if (file->f_flags & O_NONBLOCK) {} else {//wait_event_interruptible(wq_head, condition);}int ret = copy_to_user(ubuf, kbuf, size);if (ret) {printk("copy_to_user err \n");return ret;}condition = 0;return 0;
}
ssize_t mycdev_write(struct file *file, const char *ubuf, size_t size, loff_t *lof)
{return 0;
}int mycdev_close(struct inode *inode, struct file *file)
{printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);return 0;
}__poll_t mycdev_poll(struct file *file, struct poll_table_struct *wait) {__poll_t mask = 0;//向上提交等待队列头poll_wait(file, &wq_head, wait);if (condition) {mask = POLLIN;}return mask;
}// 定义操作方法结构体遍历并且初始化
struct file_operations fops = {.open = mycdev_open,.read = mycdev_read,.write = mycdev_write,.release = mycdev_close,.poll = mycdev_poll,
};irqreturn_t key_handler(int irq, void *dev)
{if (number == 0) {number = 1;} else {number = 0;}gpio_set_value(gpiono, number);condition = 1;wake_up_interruptible(&wq_head);return IRQ_HANDLED;
}static int __init mycdev_init(void)
{// 初始化等待队列头init_waitqueue_head(&wq_head);/*** 注册设备驱动*/major = register_chrdev(0, "mychrdev", &fops);if (major < 0) {printk("字符设备驱动注册失败 \n");return major;}printk("字符设备驱动注册成功\n");/*** 自动创建设备节点*///向上提交目录信息cls = class_create(THIS_MODULE, "mycdev");if (IS_ERR(cls)) {printk("向上提交目录信息失败\n");return -PTR_ERR(cls);} printk("向上提交目录信息成功\n");//向上提交设备信息dev = device_create(cls, NULL, MKDEV(major, 0), NULL, "mycdev0");if (IS_ERR(dev)) {printk("向上提交设备节点失败\n");return -PTR_ERR(cls);}/*** 中断*/dnode = of_find_compatible_node(NULL, NULL, "lxf,homework");if (dnode == NULL){printk("解析设备树节点失败\n");return -ENXIO;}printk("解析按键的设备树节点成功\n");// 获取软中断号key_irqno = irq_of_parse_and_map(dnode, 0);if (!key_irqno){printk("获取软中断号失败\n");return -1;}printk("获取软中断号成功%d\n", key_irqno);// 注册中断int ret = request_irq(key_irqno, key_handler, IRQF_TRIGGER_FALLING, "key1", NULL);if (ret < 0){printk("注册中断失败\n");return -1;}printk("注册中断成功\n");/*** LED灯*///获取gpio编号gpiono = of_get_named_gpio(dnode, "led1", 0);if (gpiono < 0) {printk("gpio编号解析失败\n");return -ENXIO;}printk("解析gpio编号成功\n");//申请gpio编号ret = gpio_request(gpiono, NULL);if (ret) {printk("申请gpio编号失败\n");return -1;}printk("申请gpio编号成功\n");//设置为输出模式gpio_direction_output(gpiono, 0);return 0;
}static void __exit mycdev_exit(void)
{device_destroy(cls, MKDEV(major, 0));class_destroy(cls);unregister_chrdev(major, "mychrdev");free_irq(key_irqno, NULL);
}module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");测试代码：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <sys/wait.h>
#include <pthread.h>
#include <signal.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/time.h>
#include <sys/epoll.h>int main(int argc, const char *argv[]) {int fd, epfd;struct epoll_event event;struct epoll_event events[10];char buf[128] = {0};epfd = epoll_create(1);if (epfd < 0) {printf("epoll_create failed \n");return -1;}fd = open("/dev/mycdev0", O_RDWR);if (fd < 0) {printf("打开文件失败\n");return -1;}event.events = EPOLLIN;event.data.fd = fd;if (epoll_ctl(epfd, EPOLL_CTL_ADD, fd, &event) < 0) {printf("epoll_ctl add failed\n");return -1;}int ret, i;while(1) {ret = epoll_wait(epfd, events, 10, -1);if (ret < 0) {printf("epoll_wait failed\n");return -1;}for (i=0; i<ret; i++) {if (events[i].events & EPOLLIN) {read(events[i].data.fd, buf, sizeof(buf));printf("%s\n", buf);}}}close(fd);return 0;
}结果展示
