通过GPIO子系统接口完成LED驱动的编写，编写应用程序控制灯亮灭（流水灯）

 驱动程序

#include <linux/init.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/gpio.h>
#include "led.h"unsigned int major;//主设备号
struct class *cls;//类指针
struct device *dev;//设备指针
struct device_node *np; // 设备树节点指针
// struct property *pp;//属性指针
int gpiono[3]; // gpio编号
char kbuf[128] = {};/*************************************封装各种操作方法*******************************************/
int mycdev_open(struct inode *inode, struct file *file)
{unsigned int minor;printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);minor = MINOR(inode->i_rdev);file->private_data = (void *)minor;return 0;
}ssize_t mycdev_read(struct file *file, char __user *ubuf, size_t size, loff_t *loff_t)
{unsigned long ret;if (size > sizeof(kbuf))size = sizeof(kbuf);ret = copy_to_user(ubuf, kbuf, size);if (ret){printk("copy_to_user filad\n");return ret;}return 0;
}ssize_t mycdev_write(struct file *file, const char __user *ubuf, size_t size, loff_t *loff_t)
{unsigned long ret;if (size > sizeof(kbuf))size = sizeof(kbuf);ret = copy_from_user(kbuf, ubuf, size);if (ret){printk("copy_from_user filad\n");return ret;}return 0;
}long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{switch (cmd){case LED_ON:switch ((unsigned int)file->private_data){case 0: // LED1控制gpio_set_value(gpiono[0], 1);break;case 1: // LED2控制gpio_set_value(gpiono[1], 1);break;case 2: // LED3控制gpio_set_value(gpiono[2], 1);break;default:break;}break;case LED_OFF:switch ((unsigned int)file->private_data){case 0: // LED1控制gpio_set_value(gpiono[0], 0);break;case 1: // LED2控制gpio_set_value(gpiono[1], 0);break;case 2: // LED3控制gpio_set_value(gpiono[2], 0);break;default:break;}break;default:break;}return 0;
}int mycdev_close(struct inode *inode, struct file *file)
{printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);return 0;
}struct file_operations fops = {.open = mycdev_open,.read = mycdev_read,.write = mycdev_write,.unlocked_ioctl = mycdev_ioctl,.release = mycdev_close,
};int all_led_init(void)
{int i;for (i = 0; i < 3; i++){gpiono[i] = of_get_named_gpio(np, "led-gpios", i); // 通过属性名字获取gpio编号if (gpiono[i] < 0){printk("get gpio failed\n");return -1;}printk("get gpio success,gpio=%d\n", gpiono[i]);// 申请解析到的gpio编号if (gpio_request(gpiono[i], NULL) < 0){printk("request gpio failed\n");return -1;}// 设置gpio为输出模式，默认输出低电平if (gpio_direction_output(gpiono[i], 0)){printk("set gpio output failed\n");return -1;}printk("set gpio output success\n");}return 0;
}static int __init mycdev_init(void)
{// int i,len;// np = of_find_node_by_name(NULL,"mynode");/**********字符设备驱动注册**********/int i;major = register_chrdev(0, "led", &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 major=%d\n", major);// 向上提交设备类cls = class_create(THIS_MODULE, "led");if (IS_ERR(cls)){printk("class_create falie\n");unregister_chrdev(major, "led");return PTR_ERR(cls);}printk("class_create success\n");// 向上提交设备信息for (i = 0; i < 3; i++){dev = device_create(cls, NULL, MKDEV(major, i), NULL, "led%d", i);if (IS_ERR(dev)){printk("device_create filed\n");class_destroy(cls);unregister_chrdev(major, "led");return PTR_ERR(dev);}printk("device_create success\n");}// 通过路径查找设备树节点np = of_find_node_by_path("/leds"); if (np == NULL){printk("find node failed\n");return -1;}printk("find node success\n");all_led_init();return 0;
}static void __exit mycdev_exit(void)
{int i;for (i = 0; i < 3; i++){gpio_free(gpiono[i]); // 释放gpiodevice_destroy(cls, MKDEV(major, i));//注销设备}// 将设备类注销class_destroy(cls);/*注销设备驱动*/unregister_chrdev(major, "led");printk("unregister_chrdev success\n");
}module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");

应用程序

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <pthread.h>
#include "led.h"int stop_thread = 0; // 全局变量，用于控制线程停止
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;void *led_ctl(void *arg)
{int *fd = (int *)arg;while (1){pthread_mutex_lock(&mutex);if (stop_thread){pthread_mutex_unlock(&mutex);break;}pthread_mutex_unlock(&mutex);ioctl(fd[0], LED_ON);ioctl(fd[1], LED_OFF);ioctl(fd[2], LED_OFF);sleep(1);ioctl(fd[0], LED_OFF);ioctl(fd[1], LED_ON);ioctl(fd[2], LED_OFF);sleep(1);ioctl(fd[0], LED_OFF);ioctl(fd[1], LED_OFF);ioctl(fd[2], LED_ON);sleep(1);}return NULL;
}int main(int argc, char const *argv[])
{int a,i;int fd[3];pthread_t tid;fd[0] = open("/dev/led0", O_RDWR);if (fd[0] < 0){perror("open");exit(1);}fd[1] = open("/dev/led1", O_RDWR);if (fd[1] < 0){perror("open");exit(1);}fd[2] = open("/dev/led2", O_RDWR);if (fd[2] < 0){perror("open");exit(1);}printf("open success\n");while (1){printf("请输入控制操作:0(关闭) 1(打开)\n");printf("请输入:");scanf("%d", &a);switch (a){case 0:{pthread_mutex_lock(&mutex);stop_thread = 1; // 设置全局变量，通知线程停止pthread_mutex_unlock(&mutex);pthread_join(tid, NULL);for(i=0;i<3;i++){ioctl(fd[i], LED_OFF);printf("i=%d\n",i);}}break;case 1:{pthread_mutex_lock(&mutex);stop_thread = 0; // 重置全局变量pthread_mutex_unlock(&mutex);if (pthread_create(&tid, NULL, led_ctl, fd) != 0){perror("pthread_create");exit(1);}}break;default:break;}}for(i=0;i<3;i++){close(fd[i]);}return 0;
}