linux 添加字符设备驱动程序及测试程序

#include "linux/kernel.h" #include "linux/module.h" #include "linux/fs.h" #include "linux/init.h" #include "linux/types.h" #include "linux/errno.h" #include "linux/uaccess.h" #include "linux/kdev_t.h" #define MAX_SIZE 1024 static int my_open(struct inode *inode, struct file *file); static int my_release(struct inode *inode, struct file *file); static ssize_t my_read(struct file *file, char __user *user, size_t t, loff_t *f); static ssize_t my_write(struct file *file, const char __user *user, size_t t, loff_t *f); static char message[MAX_SIZE] = "-------congratulations--------!"; static int device_num = 0;//设备号 static int counter = 0;//计数用 static int mutex = 0;//互斥用 static char* devName = "myDevice";//设备名 struct file_operations pStruct = { open:my_open, release:my_release, read:my_read, write:my_write, }; /* 注册模块 */ int init_module() { int ret; /* 函数中第一个参数是告诉系统，新注册的设备的主设备号由系统分配， * 第二个参数是新设备注册时的设备名字， * 第三个参数是指向file_operations的指针， * 当用设备号为0创建时，系统一个可以用的设备号创建模块 */ ret = register_chrdev(0, devName, &pStruct); if (ret < 0) { printk("regist failure!\n"); return -1; } else { printk("the device has been registered!\n"); device_num = ret; printk("<1>the virtual device's major number %d.\n", device_num); printk("<1>Or you can see it by using\n"); printk("<1>------more /proc/devices-------\n"); printk("<1>To talk to the driver,create a dev file with\n"); printk("<1>------'mknod /dev/myDevice c %d 0'-------\n", device_num); printk("<1>Use \"rmmode\" to remove the module\n"); return 0; } } /* 注销模块，函数名很特殊 */ void cleanup_module() { unregister_chrdev(device_num, devName); printk("unregister it success!\n"); } static int my_open(struct inode *inode, struct file *file) { if(mutex) return -EBUSY; mutex = 1;//上锁 printk("<1>main device : %d\n", MAJOR(inode->i_rdev)); printk("<1>slave device : %d\n", MINOR(inode->i_rdev)); printk("<1>%d times to call the device\n", ++counter); try_module_get(THIS_MODULE); return 0; } /* 每次使用完后会release */ static int my_release(struct inode *inode, struct file *file) { printk("Device released!\n"); module_put(THIS_MODULE); mutex = 0;//开锁 return 0; } static ssize_t my_read(struct file *file, char __user *user, size_t t, loff_t *f) { if(copy_to_user(user,message,sizeof(message))) { return -EFAULT; } return sizeof(message); } static ssize_t my_write(struct file *file, const char __user *user, size_t t, loff_t *f) { if(copy_from_user(message,user,sizeof(message))) { return -EFAULT; } return sizeof(message); }