/*
 * Loadable module to replace the stock console beep routine
 *
 * Requires patches to .../linux/drivers/char/vt_kern.h and
 * .../linux/drivers/char/vt.c
 *
 * dave madden <dhm@proteon.com>
 *
 * changed the patches and some includes for 2.0.21
 * changed calculating different legth and note
 * and changed it up to kernel 2.2.13
 * Gernot Zander <hifi@scorpio.in-berlin.de>
 *
 * Almost totally changed (while sharing a lot of code) by JFM
 * to use "fancy beep" device and userspace beep daemon.  Incorporates
 * some code by Bernd Meyer <bernie@wombat.hanse.de>  See file COPYING
 * for license information.
 *
 * Version 0.01: initial released version.
 * Version 0.02: fallback to speaker beep if there is not a beepd
 *               listening.
 *
 * v 0.02-2.4.0: cleaned up somewhat and modified to fit 2.4.x kernels
 * Frank Johnson <ratty@they.org>
 */


/* Kernel includes */
#include <linux/module.h>
#include <linux/version.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <asm/uaccess.h>
#include <linux/init.h>

/*
 * Definitions
 */
#define BEEP_MAJOR 10
#define BEEP_MINOR 128

/*
 * Static data
 */

static DECLARE_WAIT_QUEUE_HEAD (beep_wait);
static int beep_listening=0;
static char what_beep=0;

extern void	(*kd_nosound)( unsigned long ignored );
extern void	(*kd_mksound)( unsigned int count, unsigned int ticks ); 

static void	(*old_nosound)( unsigned long ignored );
static void	(*old_mksound)( unsigned int count, unsigned int ticks );

static void	 my_nosound( unsigned long ignored );
static void	 my_mksound( unsigned int count, unsigned int ticks );


static int activate_beep(char beepkind)
{
#ifdef DEBUG
	printk("activate_beep called.\n");
#endif
	what_beep=beepkind;
	wake_up(&beep_wait);
	return 0;
}

static int close_beep(struct inode * inode, struct file * file)
{
#ifdef DEBUG
	printk(KERN_WARNING "close_beep called\n");
#endif
	if ((file->f_flags & O_ACCMODE) == O_RDONLY)
	{
		if (beep_listening)
		{
			beep_listening--;
			MOD_DEC_USE_COUNT;
		}
	}
	return(0);
}

/*
 * open access to the beep, currently only one reading open is
 * allowed. We can do as many writes as we like. This really calls 
 * for some kind of buffering of events, something more accurate than
 * the simple static what_beep. Later.... 
 */

static int open_beep(struct inode * inode, struct file * file)
{
#ifdef DEBUG
	printk(KERN_WARNING "open_beep called.\n");
#endif
	switch(file->f_flags & O_ACCMODE)
		{
		case O_RDONLY:
			if (beep_listening)
				return -EBUSY;
			MOD_INC_USE_COUNT;
			beep_listening++;
			what_beep=0; /* Zero means we don't have any beeps waiting to be fetched */
			return 0;
		case O_NONBLOCK:
			return -EAGAIN;
		case O_WRONLY:
			return 0;
		default:
			return -EINVAL;
		}
}

static ssize_t read_beep(struct file * file, char * buffer, size_t len,
			 loff_t *ppos)
{
	size_t bytes_sent=0;

	/* Can't seek (pread) on this device */
	if (ppos != &file->f_pos)
		return -ESPIPE;

	if (!access_ok(VERIFY_WRITE, buffer, sizeof(what_beep))) {
		what_beep = 0;
		return -EFAULT;
	}
	if (!beep_listening) /* Pretty improbable...*/
	{
#ifdef DEBUG
		printk("beep: no one listening.\n");
#endif
		return -EAGAIN;
		/* Uh? Is this a good return value? */
	}
	
	/* OK, now for the fun bit.... I never did anything in kernel space
	 * before, so if this is completely foolish, just tell me, OK?
	 */
	
	while (!what_beep) {
		interruptible_sleep_on(&beep_wait);
		/* We need to handle the reader being signaled. */
		if (signal_pending(current)) {
			if (beep_listening) {
				beep_listening--;
				MOD_DEC_USE_COUNT;
			}
			return -EINTR;
		}
	}

	while ((len>0) && (what_beep>0)) {
		put_user(what_beep, buffer);
		what_beep--;
		len--;
		bytes_sent++;
	}
#ifdef DEBUG
	printk("Beep!\n");
#endif
	return(bytes_sent);
}

struct file_operations beep_fops = {
	read: read_beep,
	open: open_beep,
	release: close_beep,
};

static struct miscdevice beep_device = {
	BEEP_MINOR,
	"beep",
	&beep_fops
};

int __init beep_init(void)
{
	/* Try to register device */
	int rc;

	rc = misc_register(&beep_device);
	if (rc < 0)
	{
		printk(KERN_WARNING "beep: can't get misc device %d\n", BEEP_MINOR);
		return(rc);
	}
	printk( "Replacing keyboard beeper\n" );
	
	kd_nosound( 0 );	       	/* make sure the beeper is turned off now */

	old_nosound = kd_nosound;
	old_mksound = kd_mksound;

	kd_nosound = my_nosound;
	kd_mksound = my_mksound;
	
	return 0;
}

static void	 my_nosound(unsigned long ignored)
{
	/* Turn off beeping somehow. */
}

static void	 my_mksound(unsigned int count, unsigned int ticks)
{
	/* Do a single beep */
	if (beep_listening)
		activate_beep(1);
	else
		old_mksound(count, ticks);
}

int init_module(void)
{
	return beep_init();
}

static void __exit beep_cleanup_module(void)
{
	misc_deregister(&beep_device);
	printk( "Restoring old keyboard beeper\n" );

	kd_nosound( 0 );

	kd_nosound = old_nosound;
	kd_mksound = old_mksound;
}

module_exit(beep_cleanup_module);