20230712-----阻塞IO驱动按键控制LED灯的亮灭-编程知识

20230712-----阻塞IO驱动按键控制LED灯的亮灭

驱动程序

#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/interrupt.h>
#include <linux/gpio.h>
#include <linux/of_gpio.h>struct cdev *cdev;
unsigned int major = 500;
unsigned int minor = 0; // 次设备号的起始值
dev_t devno;
struct class *cls;
struct device *dev;
// 定义等待队列头
wait_queue_head_t wq_head;
unsigned int condition = 0;unsigned int number;
struct device_node *dnode;
unsigned int irqno;
struct gpio_desc *gpiono;// 中断处理函数
irqreturn_t myirq_handler(int irqno, void *dev_id)
{if (number == 0){number = 1;gpiod_set_value(gpiono, 1); // 亮灯}else{number = 0;gpiod_set_value(gpiono, 0); // 灭灯}condition=1;//表示硬件数据就绪wake_up_interruptible(&wq_head);//唤醒休眠的进程//printk("number = %d\n", number); // 打印此时的number的值return IRQ_HANDLED;
}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)
{printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);int ret;// 向用户空间读取拷贝if (size > sizeof(number)) // 用户空间期待读取的大小内核满足不了，那就给内核支持的最大大小size = sizeof(number);wait_event_interruptible(wq_head, condition); // 将进程切换为休眠ret = copy_to_user(ubuf, &number, size);if (ret) // 拷贝失败{printk("copy_to_user filed\n");return ret;}condition = 0; // 表示下一次硬件数据没有准备好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;
}// 定义操作方法结构体变量并赋值
struct file_operations fops = {.open = mycdev_open,.read = mycdev_read,.write = mycdev_write,.release = mycdev_close,
};static int __init mycdev_init(void)
{int ret, i;// 初始化等待队列头init_waitqueue_head(&wq_head);// 1.分配字符设备驱动对象空间  cdev_alloccdev = cdev_alloc();if (cdev == NULL){printk("申请字符设备驱动对象空间失败\n");ret = -EFAULT;goto out1;}printk("字符设备驱动对象申请成功\n");// 2.字符设备驱动对象部分初始化  cdev_initcdev_init(cdev, &fops);// 3.申请设备号  register_chrdev_region/alloc_chrdev_regionif (major > 0) // 静态申请设备号{ret = register_chrdev_region(MKDEV(major, minor), 3, "mykeys");if (ret){printk("静态指定设备号失败\n");goto out2;}}else // 动态申请设备号{ret = alloc_chrdev_region(&devno, minor, 3, "mykeys");if (ret){printk("动态申请设备号失败\n");goto out2;}major = MAJOR(devno); // 根据设备号得到主设备号minor = MINOR(devno); // 根据设备号得到次设备号}printk("申请设备号成功\n");// 4.注册字符设备驱动对象  cdev_add()ret = cdev_add(cdev, MKDEV(major, minor), 3);if (ret){printk("注册字符设备驱动对象失败\n");goto out3;}printk("注册字符设备驱动对象成功\n");// 5.向上提交目录cls = class_create(THIS_MODULE, "mykeys");if (IS_ERR(cls)){printk("向上提交目录失败\n");ret = -PTR_ERR(cls);goto out4;}printk("向上提交目录成功\n");// 6.向上提交设备节点for (i = 0; i < 3; i++){dev = device_create(cls, NULL, MKDEV(major, i), NULL, "mykeys%d", i);if (IS_ERR(dev)){printk("向上提交节点信息失败\n");ret = -PTR_ERR(dev);goto out5;}}printk("向上提交设备节点信息成功\n");// 解析设备树节点dnode = of_find_node_by_name(NULL, "mykeys");if (dnode == NULL){printk("解析设备树节点失败\n");return -ENXIO;}printk("解析设备树节点成功\n");// 获取软中断号irqno = irq_of_parse_and_map(dnode, 0);if (!irqno){printk("软中断号获取失败\n");return -ENOMEM;}printk("软中断号获取成功 irqno = %d\n", irqno);// 注册中断ret = request_irq(irqno, myirq_handler, IRQF_TRIGGER_FALLING, "key1", NULL);if (ret){printk("注册驱动失败\n");return ret;}printk("key1中断注册成功\n");// 根据设备树节点解析led1 gpio结构体并向内核注册gpiono = gpiod_get_from_of_node(dnode, "led1", 0, GPIOD_OUT_LOW, NULL);if (IS_ERR(gpiono)){printk("申请gpio失败\n");return -PTR_ERR(gpiono);}return 0;out5:for (--i; i >= 0; i--){// 销毁上面提交的设备信息device_destroy(cls, MKDEV(major, i));}class_destroy(cls);
out4:cdev_del(cdev);
out3:unregister_chrdev_region(MKDEV(major, minor), 3);
out2:kfree(cdev);
out1:return ret;
}
static void __exit mycdev_exit(void)
{// 1.销毁设备信息  device_destroyint i;for (i = 0; i < 3; i++){device_destroy(cls, MKDEV(major, i));}// 2.销毁目录  class_destroyclass_destroy(cls);// 3.注销对象  cdev_del()cdev_del(cdev);// 4.释放设备号   unregister_chrdev_region()unregister_chrdev_region(MKDEV(major, minor), 3);// 5.释放对象空间  kfree()kfree(cdev);// 注销中断free_irq(irqno, NULL);// 注销gpio信息gpiod_put(gpiono);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

应用程序

#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>int main(int argc, char const *argv[])
{unsigned int number;int fd = open("/dev/mykeys0", O_RDWR);if (fd < 0){printf("打开设备文件失败\n");exit(-1);}while(1){read(fd,&number,sizeof(number));//读取数据printf("number = %d\n",number);}close(fd);return 0;
}