lp.c

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/*
 * 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, [email protected]
 * Statistics and support for slow printers by Rob Janssen, [email protected]
 * "lp=" command line parameters added by Grant Guenther, [email protected]
 * lp_read (Status readback) support added by Carsten Gross,
 *                                             [email protected]
 * Support for parport by Philip Blundell <[email protected]>
 * Parport sharing hacking by Andrea Arcangeli
 * Fixed kernel_(to/from)_user memory copy to check for errors
 *              by Riccardo Facchetti <[email protected]>
 * 22-JAN-1998  Added support for devfs  Richard Gooch <[email protected]>
 * 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/errno.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/sched.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/mutex.h>
#include <linux/compat.h>

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

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

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

static DEFINE_MUTEX(lp_mutex);
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;
#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_path.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 (mutex_lock_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:
    mutex_unlock(&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_path.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 (mutex_lock_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;

    mutex_unlock(&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);
    int ret = 0;

    mutex_lock(&lp_mutex);
    if (minor >= LP_NO) {
        ret = -ENXIO;
        goto out;
    }
    if ((LP_F(minor) & LP_EXIST) == 0) {
        ret = -ENXIO;
        goto out;
    }
    if (test_and_set_bit(LP_BUSY_BIT_POS, &LP_F(minor))) {
        ret = -EBUSY;
        goto out;
    }
    /* 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;
            ret = -ENOSPC;
            goto out;
        } else if (!(status & LP_PSELECD)) {
            printk(KERN_INFO "lp%d off-line\n", minor);
            LP_F(minor) &= ~LP_BUSY;
            ret = -EIO;
            goto out;
        } else if (!(status & LP_PERRORP)) {
            printk(KERN_ERR "lp%d printer error\n", minor);
            LP_F(minor) &= ~LP_BUSY;
            ret = -EIO;
            goto out;
        }
    }
    lp_table[minor].lp_buffer = kmalloc(LP_BUFFER_SIZE, GFP_KERNEL);
    if (!lp_table[minor].lp_buffer) {
        LP_F(minor) &= ~LP_BUSY;
        ret = -ENOMEM;
        goto out;
    }
    /* 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;
out:
    mutex_unlock(&lp_mutex);
    return ret;
}

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_do_ioctl(unsigned int minor, unsigned int cmd,
    unsigned long arg, void __user *argp)
{
    int status;
    int retval = 0;

#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 ) {
        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;

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

static int lp_set_timeout(unsigned int minor, struct timeval *par_timeout)
{
    long to_jiffies;

    /* Convert to jiffies, place in lp_table */
    if ((par_timeout->tv_sec < 0) ||
        (par_timeout->tv_usec < 0)) {
        return -EINVAL;
    }
    to_jiffies = DIV_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;
    return 0;
}

static long lp_ioctl(struct file *file, unsigned int cmd,
            unsigned long arg)
{
    unsigned int minor;
    struct timeval par_timeout;
    int ret;

    minor = iminor(file->f_path.dentry->d_inode);
    mutex_lock(&lp_mutex);
    switch (cmd) {
    case LPSETTIMEOUT:
        if (copy_from_user(&par_timeout, (void __user *)arg,
                    sizeof (struct timeval))) {
            ret = -EFAULT;
            break;
        }
        ret = lp_set_timeout(minor, &par_timeout);
        break;
    default:
        ret = lp_do_ioctl(minor, cmd, arg, (void __user *)arg);
        break;
    }
    mutex_unlock(&lp_mutex);

    return ret;
}

#ifdef CONFIG_COMPAT
static long lp_compat_ioctl(struct file *file, unsigned int cmd,
            unsigned long arg)
{
    unsigned int minor;
    struct timeval par_timeout;
    int ret;

    minor = iminor(file->f_path.dentry->d_inode);
    mutex_lock(&lp_mutex);
    switch (cmd) {
    case LPSETTIMEOUT:
        if (compat_get_timeval(&par_timeout, compat_ptr(arg))) {
            ret = -EFAULT;
            break;
        }
        ret = lp_set_timeout(minor, &par_timeout);
        break;
#ifdef LP_STATS
    case LPGETSTATS:
        /* FIXME: add an implementation if you set LP_STATS */
        ret = -EINVAL;
        break;
#endif
    default:
        ret = lp_do_ioctl(minor, cmd, arg, compat_ptr(arg));
        break;
    }
    mutex_unlock(&lp_mutex);

    return ret;
}
#endif

static const struct file_operations lp_fops = {
    .owner      = THIS_MODULE,
    .write      = lp_write,
    .unlocked_ioctl = lp_ioctl,
#ifdef CONFIG_COMPAT
    .compat_ioctl   = lp_compat_ioctl,
#endif
    .open       = lp_open,
    .release    = lp_release,
#ifdef CONFIG_PARPORT_1284
    .read       = lp_read,
#endif
    .llseek     = noop_llseek,
};

/* --- 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];
static bool reset;

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;
    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);

    device_create(lp_class, port->dev, MKDEV(LP_MAJOR, nr), NULL,
              "lp%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);
        mutex_init(&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;
    }

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

    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_reg:
    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);
        device_destroy(lp_class, MKDEV(LP_MAJOR, offset));
    }
    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");