#include <linux/errno.h>#include <linux/miscdevice.h>	/* for misc_register, and SYNTH_MINOR */#include <linux/types.h>#include <linux/uaccess.h> #include "speakup.h"#include "spk_priv.h" #ifndef SYNTH_MINOR#define SYNTH_MINOR 25#endif static int misc_registered;static int dev_opened; static ssize_t speakup_file_write(struct file *fp, const char __user *buffer,				  size_t nbytes, loff_t *ppos){	size_t count = nbytes;	const char __user *ptr = buffer;	size_t bytes;	unsigned long flags;	u_char buf[256]; 	if (synth == NULL)		return -ENODEV;	while (count > 0) {		bytes = min(count, sizeof(buf));		if (copy_from_user(buf, ptr, bytes))			return -EFAULT;		count -= bytes;		ptr += bytes;		spin_lock_irqsave(&speakup_info.spinlock, flags);		synth_write(buf, bytes);		spin_unlock_irqrestore(&speakup_info.spinlock, flags);	}	return (ssize_t) nbytes;} static ssize_t speakup_file_read(struct file *fp, char __user *buf,				 size_t nbytes, loff_t *ppos){	return 0;} static int speakup_file_open(struct inode *ip, struct file *fp){	if (synth == NULL)		return -ENODEV;	if (xchg(&dev_opened, 1))		return -EBUSY;	return 0;} static int speakup_file_release(struct inode *ip, struct file *fp){	dev_opened = 0;	return 0;} static const struct file_operations synth_fops = {	.read = speakup_file_read,	.write = speakup_file_write,	.open = speakup_file_open,	.release = speakup_file_release,}; static struct miscdevice synth_device = {	.minor = SYNTH_MINOR,	.name = "synth",	.fops = &synth_fops,}; void speakup_register_devsynth(void){	if (misc_registered != 0)		return;/* zero it so if register fails, deregister will not ref invalid ptrs */	if (misc_register(&synth_device))		pr_warn("Couldn't initialize miscdevice /dev/synth.\n");	else {		pr_info("initialized device: /dev/synth, node (MAJOR %d, MINOR %d)\n",			MISC_MAJOR, SYNTH_MINOR);		misc_registered = 1;	}} void speakup_unregister_devsynth(void){	if (!misc_registered)		return;	pr_info("speakup: unregistering synth device /dev/synth\n");	misc_deregister(&synth_device);	misc_registered = 0;}