本文章参考正点原子相关教程,仅学习记录使用 驱动代码流程流程
//打开文件 static int chrdevbase_open(struct inode *inode, struct file *flip) //读文件 static ssize_t chrdevbase_read(struct file *filp, char __user *buf, size_t cnt, loff_t *offt) //写文件 static ssize_t chrdevbase_write(struct file *flip, const char __user *buf, size_t cnt, loff_t *offt) //关闭文件 static int chrdevbase_release(struct inode *inode, struct file *filp) //驱动函数配置函数 static struct file_operations chrdevbase_fops = { .owner = THIS_MODULE, .open = chrdevbase_open, .read = chrdevbase_read, .write = chrdevbase_write, .release = chrdevbase_release, }; //驱动初始化 static int __init chrdevbase_init(void) int register_chrdev_region(dev_t from, unsigned count, const char *name) // 注册驱动 //卸载驱动 static void __exit chrdevbase_exit(void) int unregister_chrdev(dev_t from, const char *name) //模块初始化驱动初始化、卸载函数 module_init(chrdevbase_init); module_exit(chrdevbase_exit); //协议、作者 MODULE_LICENSE("GPL"); MODULE_AUTHOR("TAN");测试函数
//上述实现用户层函数与底层寄存器建立联系，使用linux用户层提供的open,read,write,close实现驱动操作。 #include "stdio.h" #include "unistd.h" #include "sys/types.h" #include "sys/stat.h" #include "fcntl.h" #include "stdlib.h" #include "string.h" static char user_data[] = {"usr data!"}; int main(int argc, char const *argv[]) { int fd , ret; char *filename; char readbuf[100], writebuf[100]; if(argc != 3){ printf("Error usage!\n"); return -1; } filename = argv[1]; fd = open(filename, O_RDWR); if(fd < 0 ){ printf ( "can`t open file %s \n.", filename); return -1; } **加粗样式**if(atoi(argv[2] == 1)){ /*read data */ ret = read(fd, readbuf, 50); if(ret < 0 ){ printf("read data %s failed!\n", filename); return -1; }else{ printf("read data: %s \n",readbuf); } }else if(atoi(argv[2] == 2)){ /*write data */ memcpy(writebuf, user_data, sizeof(user_data)); ret = write(fd, writebuf, 50); if( ret < 0 ){ printf("write file %s failed.\n", filename); } } ret = close(fd); if(ret < 0){ printf("close file %s failed.\n",filename); return -1; } return 0; return 0; }