Linux character device driver framework (old method)

#include <linux/module.h> #include <linux/kernel.h> #include <linux/init.h> #include <linux/fs.h > #include <linux/delay.h> #include <asm/uaccess.h> #include <asm/irq.h> #include <asm/io.h > #include <asm/arch/regs-gpio.h> #include <asm/hardware.h> #include <linux/cdev.h> #include < Linux/types.h> #defineXxx_device_count1/* Automatically create device node class */static struct class *xxx_dev_class;static struct Class_device *xxx_dev_class_dev;/*XXX Device related operating functions: Open, read, write, close, IOCTL, etc. */static int xxx_dev_open (struct inode *inode, struct file *filp) {PRINTK ("Open xxx device ok.\n");return 0;} static int xxx_dev_close (struct inode *inode, struct file *filp) {PRINTK ("Close xxx device ok.\n");return 0;} static int xxx_dev_write (struct file *file, const char __user *buf, size_t count, loff_t *ppos) {PRINTK ("Write xxx device ok.\n");return 0;} static int xxx_dev_read (struct file *file, const char __user *buf, size_t count, loff_t PPOs) {PRINTK ("Read xxx device ok.\n");return 0;} static int xxx_dev_ioctl (struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg) {PRINTK ("Driver:get cmd%d.\n", cmd);return 0;} /*XXX device operation function structure body */struct file_operations xxx_fops = {. Owner = This_module,. open = Xxx_dev_open,. Release = Xxx_dev_close,. Read = Xxx_dev_read,. write = Xxx_dev_write,. IOCTL = xxx_dev_ioctl,};/*XXX Device driver module registration and uninstallation */int xxx_major = 0;static int __init initialization_xxx_dev (void) {/* Register the device number */PRINTK ("before register xxx Major =%d\n", xxx_major);if (xxx_major) {Register_chrdev (xxx_major, "xxx", &xxx_fops);} else {Xxx_major = Register_chrdev (0, "xxx", &xxx_fops);}PRINTK ("after register xxx Major =%d\n", xxx_major);/* Automatically generate device node */Xxx_dev_class = Class_create (This_module, "Xxx_dev");Xxx_dev_class_dev = class_device_create (Xxx_dev_class, NULL, MKDEV (xxx_major, 0), NULL, "XXX");/* Module initialization must return 0 */PRINTK ("Module register ok.\n");return 0;} static void __exit Cleanup_xxx_dev (void) {/* Delete device files */Unregister_chrdev (xxx_major, "xxx");Class_device_unregister (Xxx_dev_class_dev);Class_destroy (Xxx_dev_class);PRINTK ("Module unregister ok.\n");} /*Module registration and uninstallation */module_init (Initialization_xxx_dev); Module_exit (Cleanup_xxx_dev);/*Module reference: Insmod Char_driver_frame_old.ko xxx_major=xxx*/module_param (xxx_major, int, s_irugo);/*The relevant declaration of the module */module_author ("Lhbo"); Module_description ("GPIO Driver for xxx"); Module_license ("GPL");