/* * usirq * use interrupts from userspace. *  * (c) copyright 1999 Eric Lammerts <eric@scintilla.utwente.nl> * $Id: usirq.c,v 1.4 1999/08/15 10:54:12 eric Exp $ *  * This is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published * by the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. *  * It is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. * See the GNU General Public License for more details. *  * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */#define __KERNEL__#define MODULE#include <linux/version.h>#include <linux/module.h>#include <linux/sched.h>#include <linux/kernel.h>#include <linux/interrupt.h>#include <linux/fcntl.h>#include <linux/errno.h>#include <asm/irq.h>MODULE_AUTHOR("Eric Lammerts <eric@scintilla.utwente.nl");MODULE_DESCRIPTION("Userspace interrupt driver");#define MAX_IRQS 16MODULE_PARM(debug,"i");static int debug;static struct {	int open:1;	int enabled:1;	struct wait_queue *waitq;} usirq[MAX_IRQS];static void usirq_interrupt(int irq, void *dev_id, struct pt_regs *regs){  //disable_irq_nosync(irq);  disable_irq(irq);	if(debug) printk("usirq_interrupt: disable_irq_nosync(%d)\n", irq);	usirq[irq].enabled = 0;	if(usirq[irq].waitq)		wake_up_interruptible(&usirq[irq].waitq);}static int usirq_open(struct inode * inode, struct file * file){	unsigned int retval;	int minor = MINOR(inode->i_rdev);	if (usirq[minor].open)		return -EBUSY;	usirq[minor].enabled = 1;	retval = request_irq(minor, usirq_interrupt, 0, "usirq", NULL);	if (retval < 0)		return retval;	cli();	if(usirq[minor].enabled) disable_irq(minor);	sti();	usirq[minor].open = 1;	MOD_INC_USE_COUNT;	return 0;}static int usirq_close(struct inode * inode, struct file * file){	int minor = MINOR(inode->i_rdev);	usirq[minor].open = 0;	free_irq(minor, NULL);	MOD_DEC_USE_COUNT;	return 0;}static ssize_t usirq_read(struct file *file, char *buf, size_t nbytes, loff_t *ppos){	int minor = MINOR(file->f_dentry->d_inode->i_rdev);		usirq[minor].enabled = 1;	if(debug) printk("usirq_read: enable_irq(%d)\n", minor);	enable_irq(minor);	if(!usirq[minor].enabled) /* apparently the irq happened right away */		return 0;			if(!(file->f_flags & O_NONBLOCK))		interruptible_sleep_on(&usirq[minor].waitq);	cli();	if(usirq[minor].enabled) {		disable_irq(minor);		if(debug) printk("usirq_read: disable_irq(%d)\n", minor);	}	sti();	if(!(file->f_flags & O_NONBLOCK)) {		current->state = TASK_RUNNING;		usirq[minor].waitq = NULL;		if(signal_pending(current))			return -ERESTARTSYS;	}	if(!usirq[minor].enabled)	/* interrupt occurred */		return 0;	if(file->f_flags & O_NONBLOCK)		return -EAGAIN;	printk(KERN_ERR "usirq_read: no signal and no irq?!?\n");	return 0;}static struct file_operations usirq_fops = {	NULL,			/* lseek */	usirq_read,	NULL,			/* write */	NULL,			/* readdir */	NULL,			/* poll */	NULL,			/* ioctl */	NULL,			/* mmap */	usirq_open,	NULL,			/* flush */	usirq_close};int init_module(void){	if (register_chrdev(USIRQ_MAJOR, "usirq", &usirq_fops) < 0) {		printk(KERN_ERR "usirq: register_chrdev failed.\n");		return -EIO;	}	return 0;}void cleanup_module(void){	unregister_chrdev(USIRQ_MAJOR, "usirq");}