drivers/char/lp.c

/*
 * Generic parallel printer driver
 *
 * Copyright (C) 1992 by Jim Weigand and Linus Torvalds
 * Copyright (C) 1992,1993 by Michael K. Johnson
 * - Thanks much to Gunter Windau for pointing out to me where the error
 *   checking ought to be.
 * Copyright (C) 1993 by Nigel Gamble (added interrupt code)
 * Copyright (C) 1994 by Alan Cox (Modularised it)
 * LPCAREFUL, LPABORT, LPGETSTATUS added by Chris Metcalf, metcalf@lcs.mit.edu
 * Statistics and support for slow printers by Rob Janssen, rob@knoware.nl
 * "lp=" command line parameters added by Grant Guenther, grant@torque.net
 * lp_read (Status readback) support added by Carsten Gross,
 *                                             carsten@sol.wohnheim.uni-ulm.de
 * Support for parport by Philip Blundell <philb@gnu.org>
 * Parport sharing hacking by Andrea Arcangeli
 * Fixed kernel_(to/from)_user memory copy to check for errors
 * 				by Riccardo Facchetti <fizban@tin.it>
 * 22-JAN-1998  Added support for devfs  Richard Gooch <rgooch@atnf.csiro.au>
 * Redesigned interrupt handling for handle printers with buggy handshake
 *				by Andrea Arcangeli, 11 May 1998
 * Full efficient handling of printer with buggy irq handshake (now I have
 * understood the meaning of the strange handshake). This is done sending new
 * characters if the interrupt is just happened, even if the printer say to
 * be still BUSY. This is needed at least with Epson Stylus Color. To enable
 * the new TRUST_IRQ mode read the `LP OPTIMIZATION' section below...
 * Fixed the irq on the rising edge of the strobe case.
 * Obsoleted the CAREFUL flag since a printer that doesn' t work with
 * CAREFUL will block a bit after in lp_check_status().
 *				Andrea Arcangeli, 15 Oct 1998
 * Obsoleted and removed all the lowlevel stuff implemented in the last
 * month to use the IEEE1284 functions (that handle the _new_ compatibilty
 * mode fine).
 */

/* This driver should, in theory, work with any parallel port that has an
 * appropriate low-level driver; all I/O is done through the parport
 * abstraction layer.
 *
 * If this driver is built into the kernel, you can configure it using the
 * kernel command-line.  For example:
 *
 *	lp=parport1,none,parport2	(bind lp0 to parport1, disable lp1 and
 *					 bind lp2 to parport2)
 *
 *	lp=auto				(assign lp devices to all ports that
 *				         have printers attached, as determined
 *					 by the IEEE-1284 autoprobe)
 * 
 *	lp=reset			(reset the printer during 
 *					 initialisation)
 *
 *	lp=off				(disable the printer driver entirely)
 *
 * If the driver is loaded as a module, similar functionality is available
 * using module parameters.  The equivalent of the above commands would be:
 *
 *	# insmod lp.o parport=1,none,2
 *
 *	# insmod lp.o parport=auto
 *
 *	# insmod lp.o reset=1
 */

/* COMPATIBILITY WITH OLD KERNELS
 *
 * Under Linux 2.0 and previous versions, lp devices were bound to ports at
 * particular I/O addresses, as follows:
 *
 *	lp0		0x3bc
 *	lp1		0x378
 *	lp2		0x278
 *
 * The new driver, by default, binds lp devices to parport devices as it
 * finds them.  This means that if you only have one port, it will be bound
 * to lp0 regardless of its I/O address.  If you need the old behaviour, you
 * can force it using the parameters described above.
 */

/*
 * The new interrupt handling code take care of the buggy handshake
 * of some HP and Epson printer:
 * ___
 * ACK    _______________    ___________
 *                       |__|
 * ____
 * BUSY   _________              _______
 *                 |____________|
 *
 * I discovered this using the printer scanner that you can find at:
 *
 *	ftp://e-mind.com/pub/linux/pscan/
 *
 *					11 May 98, Andrea Arcangeli
 *
 * My printer scanner run on an Epson Stylus Color show that such printer
 * generates the irq on the _rising_ edge of the STROBE. Now lp handle
 * this case fine too.
 *
 *					15 Oct 1998, Andrea Arcangeli
 *
 * The so called `buggy' handshake is really the well documented
 * compatibility mode IEEE1284 handshake. They changed the well known
 * Centronics handshake acking in the middle of busy expecting to not
 * break drivers or legacy application, while they broken linux lp
 * until I fixed it reverse engineering the protocol by hand some
 * month ago...
 *
 *                                     14 Dec 1998, Andrea Arcangeli
 *
 * Copyright (C) 2000 by Tim Waugh (added LPSETTIMEOUT ioctl)
 */

#include <linux/module.h>
#include <linux/init.h>

#include <linux/config.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/sched.h>
#include <linux/smp_lock.h>
#include <linux/devfs_fs_kernel.h>
#include <linux/slab.h>
#include <linux/fcntl.h>
#include <linux/delay.h>
#include <linux/poll.h>
#include <linux/console.h>
#include <linux/device.h>
#include <linux/wait.h>
#include <linux/jiffies.h>

#include <linux/parport.h>
#undef LP_STATS
#include <linux/lp.h>

#include <asm/irq.h>
#include <asm/uaccess.h>
#include <asm/system.h>

/* if you have more than 8 printers, remember to increase LP_NO */
#define LP_NO 8

/* ROUND_UP macro from fs/select.c */
#define ROUND_UP(x,y) (((x)+(y)-1)/(y))

static struct lp_struct lp_table[LP_NO];

static unsigned int lp_count = 0;
static struct class *lp_class;

#ifdef CONFIG_LP_CONSOLE
static struct parport *console_registered; // initially NULL
#endif /* CONFIG_LP_CONSOLE */

#undef LP_DEBUG

/* Bits used to manage claiming the parport device */
#define LP_PREEMPT_REQUEST 1
#define LP_PARPORT_CLAIMED 2

/* --- low-level port access ----------------------------------- */

#define r_dtr(x)	(parport_read_data(lp_table[(x)].dev->port))
#define r_str(x)	(parport_read_status(lp_table[(x)].dev->port))
#define w_ctr(x,y)	do { parport_write_control(lp_table[(x)].dev->port, (y)); } while (0)
#define w_dtr(x,y)	do { parport_write_data(lp_table[(x)].dev->port, (y)); } while (0)

/* Claim the parport or block trying unless we've already claimed it */
static void lp_claim_parport_or_block(struct lp_struct *this_lp)
{
	if (!test_and_set_bit(LP_PARPORT_CLAIMED, &this_lp->bits)) {
		parport_claim_or_block (this_lp->dev);
	}
}

/* Claim the parport or block trying unless we've already claimed it */
static void lp_release_parport(struct lp_struct *this_lp)
{
	if (test_and_clear_bit(LP_PARPORT_CLAIMED, &this_lp->bits)) {
		parport_release (this_lp->dev);
	}
}



static int lp_preempt(void *handle)
{
	struct lp_struct *this_lp = (struct lp_struct *)handle;
	set_bit(LP_PREEMPT_REQUEST, &this_lp->bits);
	return (1);
}


/* 
 * Try to negotiate to a new mode; if unsuccessful negotiate to
 * compatibility mode.  Return the mode we ended up in.
 */
static int lp_negotiate(struct parport * port, int mode)
{
	if (parport_negotiate (port, mode) != 0) {
		mode = IEEE1284_MODE_COMPAT;
		parport_negotiate (port, mode);
	}

	return (mode);
}

static int lp_reset(int minor)
{
	int retval;
	lp_claim_parport_or_block (&lp_table[minor]);
	w_ctr(minor, LP_PSELECP);
	udelay (LP_DELAY);
	w_ctr(minor, LP_PSELECP | LP_PINITP);
	retval = r_str(minor);
	lp_release_parport (&lp_table[minor]);
	return retval;
}

static void lp_error (int minor)
{
	DEFINE_WAIT(wait);
	int polling;

	if (LP_F(minor) & LP_ABORT)
		return;

	polling = lp_table[minor].dev->port->irq == PARPORT_IRQ_NONE;
	if (polling) lp_release_parport (&lp_table[minor]);
	prepare_to_wait(&lp_table[minor].waitq, &wait, TASK_INTERRUPTIBLE);
	schedule_timeout(LP_TIMEOUT_POLLED);
	finish_wait(&lp_table[minor].waitq, &wait);
	if (polling) lp_claim_parport_or_block (&lp_table[minor]);
	else parport_yield_blocking (lp_table[minor].dev);
}

static int lp_check_status(int minor)
{
	int error = 0;
	unsigned int last = lp_table[minor].last_error;
	unsigned char status = r_str(minor);
	if ((status & LP_PERRORP) && !(LP_F(minor) & LP_CAREFUL))
		/* No error. */
		last = 0;
	else if ((status & LP_POUTPA)) {
		if (last != LP_POUTPA) {
			last = LP_POUTPA;
			printk(KERN_INFO "lp%d out of paper\n", minor);
		}
		error = -ENOSPC;
	} else if (!(status & LP_PSELECD)) {
		if (last != LP_PSELECD) {
			last = LP_PSELECD;
			printk(KERN_INFO "lp%d off-line\n", minor);
		}
		error = -EIO;
	} else if (!(status & LP_PERRORP)) {
		if (last != LP_PERRORP) {
			last = LP_PERRORP;
			printk(KERN_INFO "lp%d on fire\n", minor);
		}
		error = -EIO;
	} else {
		last = 0; /* Come here if LP_CAREFUL is set and no
                             errors are reported. */
	}

	lp_table[minor].last_error = last;

	if (last != 0)
		lp_error(minor);

	return error;
}

static int lp_wait_ready(int minor, int nonblock)
{
	int error = 0;

	/* If we're not in compatibility mode, we're ready now! */
	if (lp_table[minor].current_mode != IEEE1284_MODE_COMPAT) {
	  return (0);
	}

	do {
		error = lp_check_status (minor);
		if (error && (nonblock || (LP_F(minor) & LP_ABORT)))
			break;
		if (signal_pending (current)) {
			error = -EINTR;
			break;
		}
	} while (error);
	return error;
}

static ssize_t lp_write(struct file * file, const char __user * buf,
		        size_t count, loff_t *ppos)
{
	unsigned int minor = iminor(file->f_dentry->d_inode);
	struct parport *port = lp_table[minor].dev->port;
	char *kbuf = lp_table[minor].lp_buffer;
	ssize_t retv = 0;
	ssize_t written;
	size_t copy_size = count;
	int nonblock = ((file->f_flags & O_NONBLOCK) ||
			(LP_F(minor) & LP_ABORT));

#ifdef LP_STATS
	if (time_after(jiffies, lp_table[minor].lastcall + LP_TIME(minor)))
		lp_table[minor].runchars = 0;

	lp_table[minor].lastcall = jiffies;
#endif

	/* Need to copy the data from user-space. */
	if (copy_size > LP_BUFFER_SIZE)
		copy_size = LP_BUFFER_SIZE;

	if (down_interruptible (&lp_table[minor].port_mutex))
		return -EINTR;

	if (copy_from_user (kbuf, buf, copy_size)) {
		retv = -EFAULT;
		goto out_unlock;
	}

 	/* Claim Parport or sleep until it becomes available
 	 */
	lp_claim_parport_or_block (&lp_table[minor]);
	/* Go to the proper mode. */
	lp_table[minor].current_mode = lp_negotiate (port, 
						     lp_table[minor].best_mode);

	parport_set_timeout (lp_table[minor].dev,
			     (nonblock ? PARPORT_INACTIVITY_O_NONBLOCK
			      : lp_table[minor].timeout));

	if ((retv = lp_wait_ready (minor, nonblock)) == 0)
	do {
		/* Write the data. */
		written = parport_write (port, kbuf, copy_size);
		if (written > 0) {
			copy_size -= written;
			count -= written;
			buf  += written;
			retv += written;
		}

		if (signal_pending (current)) {
			if (retv == 0)
				retv = -EINTR;

			break;
		}

		if (copy_size > 0) {
			/* incomplete write -> check error ! */
			int error;

			parport_negotiate (lp_table[minor].dev->port, 
					   IEEE1284_MODE_COMPAT);
			lp_table[minor].current_mode = IEEE1284_MODE_COMPAT;

			error = lp_wait_ready (minor, nonblock);

			if (error) {
				if (retv == 0)
					retv = error;
				break;
			} else if (nonblock) {
				if (retv == 0)
					retv = -EAGAIN;
				break;
			}

			parport_yield_blocking (lp_table[minor].dev);
			lp_table[minor].current_mode 
			  = lp_negotiate (port, 
					  lp_table[minor].best_mode);

		} else if (need_resched())
			schedule ();

		if (count) {
			copy_size = count;
			if (copy_size > LP_BUFFER_SIZE)
				copy_size = LP_BUFFER_SIZE;

			if (copy_from_user(kbuf, buf, copy_size)) {
				if (retv == 0)
					retv = -EFAULT;
				break;
			}
		}	
	} while (count > 0);

	if (test_and_clear_bit(LP_PREEMPT_REQUEST, 
			       &lp_table[minor].bits)) {
		printk(KERN_INFO "lp%d releasing parport\n", minor);
		parport_negotiate (lp_table[minor].dev->port, 
				   IEEE1284_MODE_COMPAT);
		lp_table[minor].current_mode = IEEE1284_MODE_COMPAT;
		lp_release_parport (&lp_table[minor]);
	}
out_unlock:
	up (&lp_table[minor].port_mutex);

 	return retv;
}

#ifdef CONFIG_PARPORT_1284

/* Status readback conforming to ieee1284 */
static ssize_t lp_read(struct file * file, char __user * buf,
		       size_t count, loff_t *ppos)
{
	DEFINE_WAIT(wait);
	unsigned int minor=iminor(file->f_dentry->d_inode);
	struct parport *port = lp_table[minor].dev->port;
	ssize_t retval = 0;
	char *kbuf = lp_table[minor].lp_buffer;
	int nonblock = ((file->f_flags & O_NONBLOCK) ||
			(LP_F(minor) & LP_ABORT));

	if (count > LP_BUFFER_SIZE)
		count = LP_BUFFER_SIZE;

	if (down_interruptible (&lp_table[minor].port_mutex))
		return -EINTR;

	lp_claim_parport_or_block (&lp_table[minor]);

	parport_set_timeout (lp_table[minor].dev,
			     (nonblock ? PARPORT_INACTIVITY_O_NONBLOCK
			      : lp_table[minor].timeout));

	parport_negotiate (lp_table[minor].dev->port, IEEE1284_MODE_COMPAT);
	if (parport_negotiate (lp_table[minor].dev->port,
			       IEEE1284_MODE_NIBBLE)) {
		retval = -EIO;
		goto out;
	}

	while (retval == 0) {
		retval = parport_read (port, kbuf, count);

		if (retval > 0)
			break;

		if (nonblock) {
			retval = -EAGAIN;
			break;
		}

		/* Wait for data. */

		if (lp_table[minor].dev->port->irq == PARPORT_IRQ_NONE) {
			parport_negotiate (lp_table[minor].dev->port,
					   IEEE1284_MODE_COMPAT);
			lp_error (minor);
			if (parport_negotiate (lp_table[minor].dev->port,
					       IEEE1284_MODE_NIBBLE)) {
				retval = -EIO;
				goto out;
			}
		} else {
			prepare_to_wait(&lp_table[minor].waitq, &wait, TASK_INTERRUPTIBLE);
			schedule_timeout(LP_TIMEOUT_POLLED);
			finish_wait(&lp_table[minor].waitq, &wait);
		}

		if (signal_pending (current)) {
			retval = -ERESTARTSYS;
			break;
		}

		cond_resched ();
	}
	parport_negotiate (lp_table[minor].dev->port, IEEE1284_MODE_COMPAT);
 out:
	lp_release_parport (&lp_table[minor]);

	if (retval > 0 && copy_to_user (buf, kbuf, retval))
		retval = -EFAULT;

	up (&lp_table[minor].port_mutex);

	return retval;
}

#endif /* IEEE 1284 support */

static int lp_open(struct inode * inode, struct file * file)
{
	unsigned int minor = iminor(inode);

	if (minor >= LP_NO)
		return -ENXIO;
	if ((LP_F(minor) & LP_EXIST) == 0)
		return -ENXIO;
	if (test_and_set_bit(LP_BUSY_BIT_POS, &LP_F(minor)))
		return -EBUSY;

	/* If ABORTOPEN is set and the printer is offline or out of paper,
	   we may still want to open it to perform ioctl()s.  Therefore we
	   have commandeered O_NONBLOCK, even though it is being used in
	   a non-standard manner.  This is strictly a Linux hack, and
	   should most likely only ever be used by the tunelp application. */
	if ((LP_F(minor) & LP_ABORTOPEN) && !(file->f_flags & O_NONBLOCK)) {
		int status;
		lp_claim_parport_or_block (&lp_table[minor]);
		status = r_str(minor);
		lp_release_parport (&lp_table[minor]);
		if (status & LP_POUTPA) {
			printk(KERN_INFO "lp%d out of paper\n", minor);
			LP_F(minor) &= ~LP_BUSY;
			return -ENOSPC;
		} else if (!(status & LP_PSELECD)) {
			printk(KERN_INFO "lp%d off-line\n", minor);
			LP_F(minor) &= ~LP_BUSY;
			return -EIO;
		} else if (!(status & LP_PERRORP)) {
			printk(KERN_ERR "lp%d printer error\n", minor);
			LP_F(minor) &= ~LP_BUSY;
			return -EIO;
		}
	}
	lp_table[minor].lp_buffer = (char *) kmalloc(LP_BUFFER_SIZE, GFP_KERNEL);
	if (!lp_table[minor].lp_buffer) {
		LP_F(minor) &= ~LP_BUSY;
		return -ENOMEM;
	}
	/* Determine if the peripheral supports ECP mode */
	lp_claim_parport_or_block (&lp_table[minor]);
	if ( (lp_table[minor].dev->port->modes & PARPORT_MODE_ECP) &&
             !parport_negotiate (lp_table[minor].dev->port, 
                                 IEEE1284_MODE_ECP)) {
		printk (KERN_INFO "lp%d: ECP mode\n", minor);
		lp_table[minor].best_mode = IEEE1284_MODE_ECP;
	} else {
		lp_table[minor].best_mode = IEEE1284_MODE_COMPAT;
	}
	/* Leave peripheral in compatibility mode */
	parport_negotiate (lp_table[minor].dev->port, IEEE1284_MODE_COMPAT);
	lp_release_parport (&lp_table[minor]);
	lp_table[minor].current_mode = IEEE1284_MODE_COMPAT;
	return 0;
}

static int lp_release(struct inode * inode, struct file * file)
{
	unsigned int minor = iminor(inode);

	lp_claim_parport_or_block (&lp_table[minor]);
	parport_negotiate (lp_table[minor].dev->port, IEEE1284_MODE_COMPAT);
	lp_table[minor].current_mode = IEEE1284_MODE_COMPAT;
	lp_release_parport (&lp_table[minor]);
	kfree(lp_table[minor].lp_buffer);
	lp_table[minor].lp_buffer = NULL;
	LP_F(minor) &= ~LP_BUSY;
	return 0;
}

static int lp_ioctl(struct inode *inode, struct file *file,
		    unsigned int cmd, unsigned long arg)
{
	unsigned int minor = iminor(inode);
	int status;
	int retval = 0;
	void __user *argp = (void __user *)arg;

#ifdef LP_DEBUG
	printk(KERN_DEBUG "lp%d ioctl, cmd: 0x%x, arg: 0x%lx\n", minor, cmd, arg);
#endif
	if (minor >= LP_NO)
		return -ENODEV;
	if ((LP_F(minor) & LP_EXIST) == 0)
		return -ENODEV;
	switch ( cmd ) {
		struct timeval par_timeout;
		long to_jiffies;

		case LPTIME:
			LP_TIME(minor) = arg * HZ/100;
			break;
		case LPCHAR:
			LP_CHAR(minor) = arg;
			break;
		case LPABORT:
			if (arg)
				LP_F(minor) |= LP_ABORT;
			else
				LP_F(minor) &= ~LP_ABORT;
			break;
		case LPABORTOPEN:
			if (arg)
				LP_F(minor) |= LP_ABORTOPEN;
			else
				LP_F(minor) &= ~LP_ABORTOPEN;
			break;
		case LPCAREFUL:
			if (arg)
				LP_F(minor) |= LP_CAREFUL;
			else
				LP_F(minor) &= ~LP_CAREFUL;
			break;
		case LPWAIT:
			LP_WAIT(minor) = arg;
			break;
		case LPSETIRQ: 
			return -EINVAL;
			break;
		case LPGETIRQ:
			if (copy_to_user(argp, &LP_IRQ(minor),
					sizeof(int)))
				return -EFAULT;
			break;
		case LPGETSTATUS:
			lp_claim_parport_or_block (&lp_table[minor]);
			status = r_str(minor);
			lp_release_parport (&lp_table[minor]);

			if (copy_to_user(argp, &status, sizeof(int)))
				return -EFAULT;
			break;
		case LPRESET:
			lp_reset(minor);
			break;
#ifdef LP_STATS
		case LPGETSTATS:
			if (copy_to_user(argp, &LP_STAT(minor),
					sizeof(struct lp_stats)))
				return -EFAULT;
			if (capable(CAP_SYS_ADMIN))
				memset(&LP_STAT(minor), 0,
						sizeof(struct lp_stats));
			break;
#endif
 		case LPGETFLAGS:
 			status = LP_F(minor);
			if (copy_to_user(argp, &status, sizeof(int)))
				return -EFAULT;
			break;

		case LPSETTIMEOUT:
			if (copy_from_user (&par_timeout, argp,
					    sizeof (struct timeval))) {
				return -EFAULT;
			}
			/* Convert to jiffies, place in lp_table */
			if ((par_timeout.tv_sec < 0) ||
			    (par_timeout.tv_usec < 0)) {
				return -EINVAL;
			}
			to_jiffies = ROUND_UP(par_timeout.tv_usec, 1000000/HZ);
			to_jiffies += par_timeout.tv_sec * (long) HZ;
			if (to_jiffies <= 0) {
				return -EINVAL;
			}
			lp_table[minor].timeout = to_jiffies;
			break;

		default:
			retval = -EINVAL;
	}
	return retval;
}

static struct file_operations lp_fops = {
	.owner		= THIS_MODULE,
	.write		= lp_write,
	.ioctl		= lp_ioctl,
	.open		= lp_open,
	.release	= lp_release,
#ifdef CONFIG_PARPORT_1284
	.read		= lp_read,
#endif
};

/* --- support for console on the line printer ----------------- */

#ifdef CONFIG_LP_CONSOLE

#define CONSOLE_LP 0

/* If the printer is out of paper, we can either lose the messages or
 * stall until the printer is happy again.  Define CONSOLE_LP_STRICT
 * non-zero to get the latter behaviour. */
#define CONSOLE_LP_STRICT 1

/* The console must be locked when we get here. */

static void lp_console_write (struct console *co, const char *s,
			      unsigned count)
{
	struct pardevice *dev = lp_table[CONSOLE_LP].dev;
	struct parport *port = dev->port;
	ssize_t written;

	if (parport_claim (dev))
		/* Nothing we can do. */
		return;

	parport_set_timeout (dev, 0);

	/* Go to compatibility mode. */
	parport_negotiate (port, IEEE1284_MODE_COMPAT);

	do {
		/* Write the data, converting LF->CRLF as we go. */
		ssize_t canwrite = count;
		char *lf = memchr (s, '\n', count);
		if (lf)
			canwrite = lf - s;

		if (canwrite > 0) {
			written = parport_write (port, s, canwrite);

			if (written <= 0)
				continue;

			s += written;
			count -= written;
			canwrite -= written;
		}

		if (lf && canwrite <= 0) {
			const char *crlf = "\r\n";
			int i = 2;

			/* Dodge the original '\n', and put '\r\n' instead. */
			s++;
			count--;
			do {
				written = parport_write (port, crlf, i);
				if (written > 0)
					i -= written, crlf += written;
			} while (i > 0 && (CONSOLE_LP_STRICT || written > 0));
		}
	} while (count > 0 && (CONSOLE_LP_STRICT || written > 0));

	parport_release (dev);
}

static struct console lpcons = {
	.name		= "lp",
	.write		= lp_console_write,
	.flags		= CON_PRINTBUFFER,
};

#endif /* console on line printer */

/* --- initialisation code ------------------------------------- */

static int parport_nr[LP_NO] = { [0 ... LP_NO-1] = LP_PARPORT_UNSPEC };
static char *parport[LP_NO] = { NULL,  };
static int reset = 0;

module_param_array(parport, charp, NULL, 0);
module_param(reset, bool, 0);

#ifndef MODULE
static int __init lp_setup (char *str)
{
	static int parport_ptr; // initially zero
	int x;

	if (get_option (&str, &x)) {
		if (x == 0) {
			/* disable driver on "lp=" or "lp=0" */
			parport_nr[0] = LP_PARPORT_OFF;
		} else {
			printk(KERN_WARNING "warning: 'lp=0x%x' is deprecated, ignored\n", x);
			return 0;
		}
	} else if (!strncmp(str, "parport", 7)) {
		int n = simple_strtoul(str+7, NULL, 10);
		if (parport_ptr < LP_NO)
			parport_nr[parport_ptr++] = n;
		else
			printk(KERN_INFO "lp: too many ports, %s ignored.\n",
			       str);
	} else if (!strcmp(str, "auto")) {
		parport_nr[0] = LP_PARPORT_AUTO;
	} else if (!strcmp(str, "none")) {
		parport_nr[parport_ptr++] = LP_PARPORT_NONE;
	} else if (!strcmp(str, "reset")) {
		reset = 1;
	}
	return 1;
}
#endif

static int lp_register(int nr, struct parport *port)
{
	lp_table[nr].dev = parport_register_device(port, "lp", 
						   lp_preempt, NULL, NULL, 0,
						   (void *) &lp_table[nr]);
	if (lp_table[nr].dev == NULL)
		return 1;
	lp_table[nr].flags |= LP_EXIST;

	if (reset)
		lp_reset(nr);

	class_device_create(lp_class, MKDEV(LP_MAJOR, nr), NULL,
				"lp%d", nr);
	devfs_mk_cdev(MKDEV(LP_MAJOR, nr), S_IFCHR | S_IRUGO | S_IWUGO,
			"printers/%d", nr);

	printk(KERN_INFO "lp%d: using %s (%s).\n", nr, port->name, 
	       (port->irq == PARPORT_IRQ_NONE)?"polling":"interrupt-driven");

#ifdef CONFIG_LP_CONSOLE
	if (!nr) {
		if (port->modes & PARPORT_MODE_SAFEININT) {
			register_console (&lpcons);
			console_registered = port;
			printk (KERN_INFO "lp%d: console ready\n", CONSOLE_LP);
		} else
			printk (KERN_ERR "lp%d: cannot run console on %s\n",
				CONSOLE_LP, port->name);
	}
#endif

	return 0;
}

static void lp_attach (struct parport *port)
{
	unsigned int i;

	switch (parport_nr[0])
	{
	case LP_PARPORT_UNSPEC:
	case LP_PARPORT_AUTO:
		if (parport_nr[0] == LP_PARPORT_AUTO &&
		    port->probe_info[0].class != PARPORT_CLASS_PRINTER)
			return;
		if (lp_count == LP_NO) {
			printk(KERN_INFO "lp: ignoring parallel port (max. %d)\n",LP_NO);
			return;
		}
		if (!lp_register(lp_count, port))
			lp_count++;
		break;

	default:
		for (i = 0; i < LP_NO; i++) {
			if (port->number == parport_nr[i]) {
				if (!lp_register(i, port))
					lp_count++;
				break;
			}
		}
		break;
	}
}

static void lp_detach (struct parport *port)
{
	/* Write this some day. */
#ifdef CONFIG_LP_CONSOLE
	if (console_registered == port) {
		unregister_console (&lpcons);
		console_registered = NULL;
	}
#endif /* CONFIG_LP_CONSOLE */
}

static struct parport_driver lp_driver = {
	.name = "lp",
	.attach = lp_attach,
	.detach = lp_detach,
};

static int __init lp_init (void)
{
	int i, err = 0;

	if (parport_nr[0] == LP_PARPORT_OFF)
		return 0;

	for (i = 0; i < LP_NO; i++) {
		lp_table[i].dev = NULL;
		lp_table[i].flags = 0;
		lp_table[i].chars = LP_INIT_CHAR;
		lp_table[i].time = LP_INIT_TIME;
		lp_table[i].wait = LP_INIT_WAIT;
		lp_table[i].lp_buffer = NULL;
#ifdef LP_STATS
		lp_table[i].lastcall = 0;
		lp_table[i].runchars = 0;
		memset (&lp_table[i].stats, 0, sizeof (struct lp_stats));
#endif
		lp_table[i].last_error = 0;
		init_waitqueue_head (&lp_table[i].waitq);
		init_waitqueue_head (&lp_table[i].dataq);
		init_MUTEX (&lp_table[i].port_mutex);
		lp_table[i].timeout = 10 * HZ;
	}

	if (register_chrdev (LP_MAJOR, "lp", &lp_fops)) {
		printk (KERN_ERR "lp: unable to get major %d\n", LP_MAJOR);
		return -EIO;
	}

	devfs_mk_dir("printers");
	lp_class = class_create(THIS_MODULE, "printer");
	if (IS_ERR(lp_class)) {
		err = PTR_ERR(lp_class);
		goto out_devfs;
	}

	if (parport_register_driver (&lp_driver)) {
		printk (KERN_ERR "lp: unable to register with parport\n");
		err = -EIO;
		goto out_class;
	}

	if (!lp_count) {
		printk (KERN_INFO "lp: driver loaded but no devices found\n");
#ifndef CONFIG_PARPORT_1284
		if (parport_nr[0] == LP_PARPORT_AUTO)
			printk (KERN_INFO "lp: (is IEEE 1284 support enabled?)\n");
#endif
	}

	return 0;

out_class:
	class_destroy(lp_class);
out_devfs:
	devfs_remove("printers");
	unregister_chrdev(LP_MAJOR, "lp");
	return err;
}

static int __init lp_init_module (void)
{
	if (parport[0]) {
		/* The user gave some parameters.  Let's see what they were.  */
		if (!strncmp(parport[0], "auto", 4))
			parport_nr[0] = LP_PARPORT_AUTO;
		else {
			int n;
			for (n = 0; n < LP_NO && parport[n]; n++) {
				if (!strncmp(parport[n], "none", 4))
					parport_nr[n] = LP_PARPORT_NONE;
				else {
					char *ep;
					unsigned long r = simple_strtoul(parport[n], &ep, 0);
					if (ep != parport[n]) 
						parport_nr[n] = r;
					else {
						printk(KERN_ERR "lp: bad port specifier `%s'\n", parport[n]);
						return -ENODEV;
					}
				}
			}
		}
	}

	return lp_init();
}

static void lp_cleanup_module (void)
{
	unsigned int offset;

	parport_unregister_driver (&lp_driver);

#ifdef CONFIG_LP_CONSOLE
	unregister_console (&lpcons);
#endif

	unregister_chrdev(LP_MAJOR, "lp");
	for (offset = 0; offset < LP_NO; offset++) {
		if (lp_table[offset].dev == NULL)
			continue;
		parport_unregister_device(lp_table[offset].dev);
		devfs_remove("printers/%d", offset);
		class_device_destroy(lp_class, MKDEV(LP_MAJOR, offset));
	}
	devfs_remove("printers");
	class_destroy(lp_class);
}

__setup("lp=", lp_setup);
module_init(lp_init_module);
module_exit(lp_cleanup_module);

MODULE_ALIAS_CHARDEV_MAJOR(LP_MAJOR);
MODULE_LICENSE("GPL");