/*
 * usblp.c
 *
 * Copyright (c) 1999 Michael Gee       <michael@linuxspecific.com>
 * Copyright (c) 1999 Pavel Machek      <pavel@ucw.cz>
 * Copyright (c) 2000 Randy Dunlap      <rdunlap@xenotime.net>
 * Copyright (c) 2000 Vojtech Pavlik    <vojtech@suse.cz>
 # Copyright (c) 2001 Pete Zaitcev      <zaitcev@redhat.com>
 # Copyright (c) 2001 David Paschal     <paschal@rcsis.com>
 * Copyright (c) 2006 Oliver Neukum     <oliver@neukum.name>
 *
 * USB Printer Device Class driver for USB printers and printer cables
 *
 * Sponsored by SuSE
 *
 * ChangeLog:
 *      v0.1 - thorough cleaning, URBification, almost a rewrite
 *      v0.2 - some more cleanups
 *      v0.3 - cleaner again, waitqueue fixes
 *      v0.4 - fixes in unidirectional mode
 *      v0.5 - add DEVICE_ID string support
 *      v0.6 - never time out
 *      v0.7 - fixed bulk-IN read and poll (David Paschal)
 *      v0.8 - add devfs support
 *      v0.9 - fix unplug-while-open paths
 *      v0.10- remove sleep_on, fix error on oom (oliver@neukum.org)
 *      v0.11 - add proto_bias option (Pete Zaitcev)
 *      v0.12 - add hpoj.sourceforge.net ioctls (David Paschal)
 *      v0.13 - alloc space for statusbuf (<status> not on stack);
 *              use usb_alloc_coherent() for read buf & write buf;
 *      none  - Maintained in Linux kernel after v0.13
 */

/*
 * This program 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.
 *
 * This program 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/lp.h>
#include <linux/mutex.h>
#undef DEBUG
#include <linux/usb.h>
#include <linux/usb/ch9.h>
#include <linux/ratelimit.h>

/*
 * Version Information
 */
#define DRIVER_AUTHOR "Michael Gee, Pavel Machek, Vojtech Pavlik, Randy Dunlap, Pete Zaitcev, David Paschal"
#define DRIVER_DESC "USB Printer Device Class driver"

#define USBLP_BUF_SIZE          8192
#define USBLP_BUF_SIZE_IN       1024
#define USBLP_DEVICE_ID_SIZE    1024

/* ioctls: */
#define IOCNR_GET_DEVICE_ID             1
#define IOCNR_GET_PROTOCOLS             2
#define IOCNR_SET_PROTOCOL              3
#define IOCNR_HP_SET_CHANNEL            4
#define IOCNR_GET_BUS_ADDRESS           5
#define IOCNR_GET_VID_PID               6
#define IOCNR_SOFT_RESET                7
/* Get device_id string: */
#define LPIOC_GET_DEVICE_ID(len) _IOC(_IOC_READ, 'P', IOCNR_GET_DEVICE_ID, len)
/* The following ioctls were added for http://hpoj.sourceforge.net:
 * Get two-int array:
 * [0]=current protocol
 *     (1=USB_CLASS_PRINTER/1/1, 2=USB_CLASS_PRINTER/1/2,
 *         3=USB_CLASS_PRINTER/1/3),
 * [1]=supported protocol mask (mask&(1<<n)!=0 means
 *     USB_CLASS_PRINTER/1/n supported):
 */
#define LPIOC_GET_PROTOCOLS(len) _IOC(_IOC_READ, 'P', IOCNR_GET_PROTOCOLS, len)
/*
 * Set protocol
 *     (arg: 1=USB_CLASS_PRINTER/1/1, 2=USB_CLASS_PRINTER/1/2,
 *         3=USB_CLASS_PRINTER/1/3):
 */
#define LPIOC_SET_PROTOCOL _IOC(_IOC_WRITE, 'P', IOCNR_SET_PROTOCOL, 0)
/* Set channel number (HP Vendor-specific command): */
#define LPIOC_HP_SET_CHANNEL _IOC(_IOC_WRITE, 'P', IOCNR_HP_SET_CHANNEL, 0)
/* Get two-int array: [0]=bus number, [1]=device address: */
#define LPIOC_GET_BUS_ADDRESS(len) _IOC(_IOC_READ, 'P', IOCNR_GET_BUS_ADDRESS, len)
/* Get two-int array: [0]=vendor ID, [1]=product ID: */
#define LPIOC_GET_VID_PID(len) _IOC(_IOC_READ, 'P', IOCNR_GET_VID_PID, len)
/* Perform class specific soft reset */
#define LPIOC_SOFT_RESET _IOC(_IOC_NONE, 'P', IOCNR_SOFT_RESET, 0);

/*
 * A DEVICE_ID string may include the printer's serial number.
 * It should end with a semi-colon (';').
 * An example from an HP 970C DeskJet printer is (this is one long string,
 * with the serial number changed):
MFG:HEWLETT-PACKARD;MDL:DESKJET 970C;CMD:MLC,PCL,PML;CLASS:PRINTER;DESCRIPTION:Hewlett-Packard DeskJet 970C;SERN:US970CSEPROF;VSTATUS:$HB0$NC0,ff,DN,IDLE,CUT,K1,C0,DP,NR,KP000,CP027;VP:0800,FL,B0;VJ:                    ;
 */

/*
 * USB Printer Requests
 */

#define USBLP_REQ_GET_ID                        0x00
#define USBLP_REQ_GET_STATUS                    0x01
#define USBLP_REQ_RESET                         0x02
#define USBLP_REQ_HP_CHANNEL_CHANGE_REQUEST     0x00    /* HP Vendor-specific */

#define USBLP_MINORS            16
#define USBLP_MINOR_BASE        0

#define USBLP_CTL_TIMEOUT       5000                    /* 5 seconds */

#define USBLP_FIRST_PROTOCOL    1
#define USBLP_LAST_PROTOCOL     3
#define USBLP_MAX_PROTOCOLS     (USBLP_LAST_PROTOCOL+1)

/*
 * some arbitrary status buffer size;
 * need a status buffer that is allocated via kmalloc(), not on stack
 */
#define STATUS_BUF_SIZE         8

/*
 * Locks down the locking order:
 * ->wmut locks wstatus.
 * ->mut locks the whole usblp, except [rw]complete, and thus, by indirection,
 * [rw]status. We only touch status when we know the side idle.
 * ->lock locks what interrupt accesses.
 */
struct usblp {
        struct usb_device       *dev;                   /* USB device */
        struct mutex            wmut;
        struct mutex            mut;
        spinlock_t              lock;           /* locks rcomplete, wcomplete */
        char                    *readbuf;               /* read transfer_buffer */
        char                    *statusbuf;             /* status transfer_buffer */
        struct usb_anchor       urbs;
        wait_queue_head_t       rwait, wwait;
        int                     readcount;              /* Counter for reads */
        int                     ifnum;                  /* Interface number */
        struct usb_interface    *intf;                  /* The interface */
        /*
         * Alternate-setting numbers and endpoints for each protocol
         * (USB_CLASS_PRINTER/1/{index=1,2,3}) that the device supports:
         */
        struct {
                int                             alt_setting;
                struct usb_endpoint_descriptor  *epwrite;
                struct usb_endpoint_descriptor  *epread;
        }                       protocol[USBLP_MAX_PROTOCOLS];
        int                     current_protocol;
        int                     minor;                  /* minor number of device */
        int                     wcomplete, rcomplete;
        int                     wstatus;        /* bytes written or error */
        int                     rstatus;        /* bytes ready or error */
        unsigned int            quirks;                 /* quirks flags */
        unsigned int            flags;                  /* mode flags */
        unsigned char           used;                   /* True if open */
        unsigned char           present;                /* True if not disconnected */
        unsigned char           bidir;                  /* interface is bidirectional */
        unsigned char           no_paper;               /* Paper Out happened */
        unsigned char           *device_id_string;      /* IEEE 1284 DEVICE ID string (ptr) */
                                                        /* first 2 bytes are (big-endian) length */
};

#ifdef DEBUG
static void usblp_dump(struct usblp *usblp)
{
        struct device *dev = &usblp->intf->dev;
        int p;

        dev_dbg(dev, "usblp=0x%p\n", usblp);
        dev_dbg(dev, "dev=0x%p\n", usblp->dev);
        dev_dbg(dev, "present=%d\n", usblp->present);
        dev_dbg(dev, "readbuf=0x%p\n", usblp->readbuf);
        dev_dbg(dev, "readcount=%d\n", usblp->readcount);
        dev_dbg(dev, "ifnum=%d\n", usblp->ifnum);
        for (p = USBLP_FIRST_PROTOCOL; p <= USBLP_LAST_PROTOCOL; p++) {
                dev_dbg(dev, "protocol[%d].alt_setting=%d\n", p,
                        usblp->protocol[p].alt_setting);
                dev_dbg(dev, "protocol[%d].epwrite=%p\n", p,
                        usblp->protocol[p].epwrite);
                dev_dbg(dev, "protocol[%d].epread=%p\n", p,
                        usblp->protocol[p].epread);
        }
        dev_dbg(dev, "current_protocol=%d\n", usblp->current_protocol);
        dev_dbg(dev, "minor=%d\n", usblp->minor);
        dev_dbg(dev, "wstatus=%d\n", usblp->wstatus);
        dev_dbg(dev, "rstatus=%d\n", usblp->rstatus);
        dev_dbg(dev, "quirks=%d\n", usblp->quirks);
        dev_dbg(dev, "used=%d\n", usblp->used);
        dev_dbg(dev, "bidir=%d\n", usblp->bidir);
        dev_dbg(dev, "device_id_string=\"%s\"\n",
                usblp->device_id_string ?
                        usblp->device_id_string + 2 :
                        (unsigned char *)"(null)");
}
#endif

/* Quirks: various printer quirks are handled by this table & its flags. */

struct quirk_printer_struct {
        __u16 vendorId;
        __u16 productId;
        unsigned int quirks;
};

#define USBLP_QUIRK_BIDIR       0x1     /* reports bidir but requires unidirectional mode (no INs/reads) */
#define USBLP_QUIRK_USB_INIT    0x2     /* needs vendor USB init string */
#define USBLP_QUIRK_BAD_CLASS   0x4     /* descriptor uses vendor-specific Class or SubClass */

static const struct quirk_printer_struct quirk_printers[] = {
        { 0x03f0, 0x0004, USBLP_QUIRK_BIDIR }, /* HP DeskJet 895C */
        { 0x03f0, 0x0104, USBLP_QUIRK_BIDIR }, /* HP DeskJet 880C */
        { 0x03f0, 0x0204, USBLP_QUIRK_BIDIR }, /* HP DeskJet 815C */
        { 0x03f0, 0x0304, USBLP_QUIRK_BIDIR }, /* HP DeskJet 810C/812C */
        { 0x03f0, 0x0404, USBLP_QUIRK_BIDIR }, /* HP DeskJet 830C */
        { 0x03f0, 0x0504, USBLP_QUIRK_BIDIR }, /* HP DeskJet 885C */
        { 0x03f0, 0x0604, USBLP_QUIRK_BIDIR }, /* HP DeskJet 840C */
        { 0x03f0, 0x0804, USBLP_QUIRK_BIDIR }, /* HP DeskJet 816C */
        { 0x03f0, 0x1104, USBLP_QUIRK_BIDIR }, /* HP Deskjet 959C */
        { 0x0409, 0xefbe, USBLP_QUIRK_BIDIR }, /* NEC Picty900 (HP OEM) */
        { 0x0409, 0xbef4, USBLP_QUIRK_BIDIR }, /* NEC Picty760 (HP OEM) */
        { 0x0409, 0xf0be, USBLP_QUIRK_BIDIR }, /* NEC Picty920 (HP OEM) */
        { 0x0409, 0xf1be, USBLP_QUIRK_BIDIR }, /* NEC Picty800 (HP OEM) */
        { 0x0482, 0x0010, USBLP_QUIRK_BIDIR }, /* Kyocera Mita FS 820, by zut <kernel@zut.de> */
        { 0x04f9, 0x000d, USBLP_QUIRK_BIDIR }, /* Brother Industries, Ltd HL-1440 Laser Printer */
        { 0x04b8, 0x0202, USBLP_QUIRK_BAD_CLASS }, /* Seiko Epson Receipt Printer M129C */
        { 0, 0 }
};

static int usblp_wwait(struct usblp *usblp, int nonblock);
static int usblp_wtest(struct usblp *usblp, int nonblock);
static int usblp_rwait_and_lock(struct usblp *usblp, int nonblock);
static int usblp_rtest(struct usblp *usblp, int nonblock);
static int usblp_submit_read(struct usblp *usblp);
static int usblp_select_alts(struct usblp *usblp);
static int usblp_set_protocol(struct usblp *usblp, int protocol);
static int usblp_cache_device_id_string(struct usblp *usblp);

/* forward reference to make our lives easier */
static struct usb_driver usblp_driver;
static DEFINE_MUTEX(usblp_mutex);       /* locks the existence of usblp's */

/*
 * Functions for usblp control messages.
 */

static int usblp_ctrl_msg(struct usblp *usblp, int request, int type, int dir, int recip, int value, void *buf, int len)
{
        int retval;
        int index = usblp->ifnum;

        /* High byte has the interface index.
           Low byte has the alternate setting.
         */
        if ((request == USBLP_REQ_GET_ID) && (type == USB_TYPE_CLASS))
                index = (usblp->ifnum<<8)|usblp->protocol[usblp->current_protocol].alt_setting;

        retval = usb_control_msg(usblp->dev,
                dir ? usb_rcvctrlpipe(usblp->dev, 0) : usb_sndctrlpipe(usblp->dev, 0),
                request, type | dir | recip, value, index, buf, len, USBLP_CTL_TIMEOUT);
        dev_dbg(&usblp->intf->dev,
                "usblp_control_msg: rq: 0x%02x dir: %d recip: %d value: %d idx: %d len: %#x result: %d\n",
                request, !!dir, recip, value, index, len, retval);
        return retval < 0 ? retval : 0;
}

#define usblp_read_status(usblp, status)\
        usblp_ctrl_msg(usblp, USBLP_REQ_GET_STATUS, USB_TYPE_CLASS, USB_DIR_IN, USB_RECIP_INTERFACE, 0, status, 1)
#define usblp_get_id(usblp, config, id, maxlen)\
        usblp_ctrl_msg(usblp, USBLP_REQ_GET_ID, USB_TYPE_CLASS, USB_DIR_IN, USB_RECIP_INTERFACE, config, id, maxlen)
#define usblp_reset(usblp)\
        usblp_ctrl_msg(usblp, USBLP_REQ_RESET, USB_TYPE_CLASS, USB_DIR_OUT, USB_RECIP_OTHER, 0, NULL, 0)

#define usblp_hp_channel_change_request(usblp, channel, buffer) \
        usblp_ctrl_msg(usblp, USBLP_REQ_HP_CHANNEL_CHANGE_REQUEST, USB_TYPE_VENDOR, USB_DIR_IN, USB_RECIP_INTERFACE, channel, buffer, 1)

/*
 * See the description for usblp_select_alts() below for the usage
 * explanation.  Look into your /proc/bus/usb/devices and dmesg in
 * case of any trouble.
 */
static int proto_bias = -1;

/*
 * URB callback.
 */

static void usblp_bulk_read(struct urb *urb)
{
        struct usblp *usblp = urb->context;
        int status = urb->status;

        if (usblp->present && usblp->used) {
                if (status)
                        printk(KERN_WARNING "usblp%d: "
                            "nonzero read bulk status received: %d\n",
                            usblp->minor, status);
        }
        spin_lock(&usblp->lock);
        if (status < 0)
                usblp->rstatus = status;
        else
                usblp->rstatus = urb->actual_length;
        usblp->rcomplete = 1;
        wake_up(&usblp->rwait);
        spin_unlock(&usblp->lock);

        usb_free_urb(urb);
}

static void usblp_bulk_write(struct urb *urb)
{
        struct usblp *usblp = urb->context;
        int status = urb->status;

        if (usblp->present && usblp->used) {
                if (status)
                        printk(KERN_WARNING "usblp%d: "
                            "nonzero write bulk status received: %d\n",
                            usblp->minor, status);
        }
        spin_lock(&usblp->lock);
        if (status < 0)
                usblp->wstatus = status;
        else
                usblp->wstatus = urb->actual_length;
        usblp->no_paper = 0;
        usblp->wcomplete = 1;
        wake_up(&usblp->wwait);
        spin_unlock(&usblp->lock);

        usb_free_urb(urb);
}

/*
 * Get and print printer errors.
 */

static const char *usblp_messages[] = { "ok", "out of paper", "off-line", "on fire" };

static int usblp_check_status(struct usblp *usblp, int err)
{
        unsigned char status, newerr = 0;
        int error;

        mutex_lock(&usblp->mut);
        if ((error = usblp_read_status(usblp, usblp->statusbuf)) < 0) {
                mutex_unlock(&usblp->mut);
                printk_ratelimited(KERN_ERR
                                "usblp%d: error %d reading printer status\n",
                                usblp->minor, error);
                return 0;
        }
        status = *usblp->statusbuf;
        mutex_unlock(&usblp->mut);

        if (~status & LP_PERRORP)
                newerr = 3;
        if (status & LP_POUTPA)
                newerr = 1;
        if (~status & LP_PSELECD)
                newerr = 2;

        if (newerr != err) {
                printk(KERN_INFO "usblp%d: %s\n",
                   usblp->minor, usblp_messages[newerr]);
        }

        return newerr;
}

static int handle_bidir(struct usblp *usblp)
{
        if (usblp->bidir && usblp->used) {
                if (usblp_submit_read(usblp) < 0)
                        return -EIO;
        }
        return 0;
}

/*
 * File op functions.
 */

static int usblp_open(struct inode *inode, struct file *file)
{
        int minor = iminor(inode);
        struct usblp *usblp;
        struct usb_interface *intf;
        int retval;

        if (minor < 0)
                return -ENODEV;

        mutex_lock(&usblp_mutex);

        retval = -ENODEV;
        intf = usb_find_interface(&usblp_driver, minor);
        if (!intf)
                goto out;
        usblp = usb_get_intfdata(intf);
        if (!usblp || !usblp->dev || !usblp->present)
                goto out;

        retval = -EBUSY;
        if (usblp->used)
                goto out;

        /*
         * We do not implement LP_ABORTOPEN/LPABORTOPEN for two reasons:
         *  - We do not want persistent state which close(2) does not clear
         *  - It is not used anyway, according to CUPS people
         */

        retval = usb_autopm_get_interface(intf);
        if (retval < 0)
                goto out;
        usblp->used = 1;
        file->private_data = usblp;

        usblp->wcomplete = 1; /* we begin writeable */
        usblp->wstatus = 0;
        usblp->rcomplete = 0;

        if (handle_bidir(usblp) < 0) {
                usb_autopm_put_interface(intf);
                usblp->used = 0;
                file->private_data = NULL;
                retval = -EIO;
        }
out:
        mutex_unlock(&usblp_mutex);
        return retval;
}

static void usblp_cleanup(struct usblp *usblp)
{
        printk(KERN_INFO "usblp%d: removed\n", usblp->minor);

        kfree(usblp->readbuf);
        kfree(usblp->device_id_string);
        kfree(usblp->statusbuf);
        kfree(usblp);
}

static void usblp_unlink_urbs(struct usblp *usblp)
{
        usb_kill_anchored_urbs(&usblp->urbs);
}

static int usblp_release(struct inode *inode, struct file *file)
{
        struct usblp *usblp = file->private_data;

        usblp->flags &= ~LP_ABORT;

        mutex_lock(&usblp_mutex);
        usblp->used = 0;
        if (usblp->present) {
                usblp_unlink_urbs(usblp);
                usb_autopm_put_interface(usblp->intf);
        } else          /* finish cleanup from disconnect */
                usblp_cleanup(usblp);
        mutex_unlock(&usblp_mutex);
        return 0;
}

/* No kernel lock - fine */
static unsigned int usblp_poll(struct file *file, struct poll_table_struct *wait)
{
        int ret;
        unsigned long flags;

        struct usblp *usblp = file->private_data;
        /* Should we check file->f_mode & FMODE_WRITE before poll_wait()? */
        poll_wait(file, &usblp->rwait, wait);
        poll_wait(file, &usblp->wwait, wait);
        spin_lock_irqsave(&usblp->lock, flags);
        ret = ((usblp->bidir && usblp->rcomplete) ? POLLIN  | POLLRDNORM : 0) |
           ((usblp->no_paper || usblp->wcomplete) ? POLLOUT | POLLWRNORM : 0);
        spin_unlock_irqrestore(&usblp->lock, flags);
        return ret;
}

static long usblp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        struct usblp *usblp = file->private_data;
        int length, err, i;
        unsigned char newChannel;
        int status;
        int twoints[2];
        int retval = 0;

        mutex_lock(&usblp->mut);
        if (!usblp->present) {
                retval = -ENODEV;
                goto done;
        }

        dev_dbg(&usblp->intf->dev,
                "usblp_ioctl: cmd=0x%x (%c nr=%d len=%d dir=%d)\n", cmd,
                _IOC_TYPE(cmd), _IOC_NR(cmd), _IOC_SIZE(cmd), _IOC_DIR(cmd));

        if (_IOC_TYPE(cmd) == 'P')      /* new-style ioctl number */

                switch (_IOC_NR(cmd)) {

                case IOCNR_GET_DEVICE_ID: /* get the DEVICE_ID string */
                        if (_IOC_DIR(cmd) != _IOC_READ) {
                                retval = -EINVAL;
                                goto done;
                        }

                        length = usblp_cache_device_id_string(usblp);
                        if (length < 0) {
                                retval = length;
                                goto done;
                        }
                        if (length > _IOC_SIZE(cmd))
                                length = _IOC_SIZE(cmd); /* truncate */

                        if (copy_to_user((void __user *) arg,
                                        usblp->device_id_string,
                                        (unsigned long) length)) {
                                retval = -EFAULT;
                                goto done;
                        }

                        break;

                case IOCNR_GET_PROTOCOLS:
                        if (_IOC_DIR(cmd) != _IOC_READ ||
                            _IOC_SIZE(cmd) < sizeof(twoints)) {
                                retval = -EINVAL;
                                goto done;
                        }

                        twoints[0] = usblp->current_protocol;
                        twoints[1] = 0;
                        for (i = USBLP_FIRST_PROTOCOL;
                             i <= USBLP_LAST_PROTOCOL; i++) {
                                if (usblp->protocol[i].alt_setting >= 0)
                                        twoints[1] |= (1<<i);
                        }

                        if (copy_to_user((void __user *)arg,
                                        (unsigned char *)twoints,
                                        sizeof(twoints))) {
                                retval = -EFAULT;
                                goto done;
                        }

                        break;

                case IOCNR_SET_PROTOCOL:
                        if (_IOC_DIR(cmd) != _IOC_WRITE) {
                                retval = -EINVAL;
                                goto done;
                        }

#ifdef DEBUG
                        if (arg == -10) {
                                usblp_dump(usblp);
                                break;
                        }
#endif

                        usblp_unlink_urbs(usblp);
                        retval = usblp_set_protocol(usblp, arg);
                        if (retval < 0) {
                                usblp_set_protocol(usblp,
                                        usblp->current_protocol);
                        }
                        break;

                case IOCNR_HP_SET_CHANNEL:
                        if (_IOC_DIR(cmd) != _IOC_WRITE ||
                            le16_to_cpu(usblp->dev->descriptor.idVendor) != 0x03F0 ||
                            usblp->quirks & USBLP_QUIRK_BIDIR) {
                                retval = -EINVAL;
                                goto done;
                        }

                        err = usblp_hp_channel_change_request(usblp,
                                arg, &newChannel);
                        if (err < 0) {
                                dev_err(&usblp->dev->dev,
                                        "usblp%d: error = %d setting "
                                        "HP channel\n",
                                        usblp->minor, err);
                                retval = -EIO;
                                goto done;
                        }

                        dev_dbg(&usblp->intf->dev,
                                "usblp%d requested/got HP channel %ld/%d\n",
                                usblp->minor, arg, newChannel);
                        break;

                case IOCNR_GET_BUS_ADDRESS:
                        if (_IOC_DIR(cmd) != _IOC_READ ||
                            _IOC_SIZE(cmd) < sizeof(twoints)) {
                                retval = -EINVAL;
                                goto done;
                        }

                        twoints[0] = usblp->dev->bus->busnum;
                        twoints[1] = usblp->dev->devnum;
                        if (copy_to_user((void __user *)arg,
                                        (unsigned char *)twoints,
                                        sizeof(twoints))) {
                                retval = -EFAULT;
                                goto done;
                        }

                        dev_dbg(&usblp->intf->dev,
                                "usblp%d is bus=%d, device=%d\n",
                                usblp->minor, twoints[0], twoints[1]);
                        break;

                case IOCNR_GET_VID_PID:
                        if (_IOC_DIR(cmd) != _IOC_READ ||
                            _IOC_SIZE(cmd) < sizeof(twoints)) {
                                retval = -EINVAL;
                                goto done;
                        }

                        twoints[0] = le16_to_cpu(usblp->dev->descriptor.idVendor);
                        twoints[1] = le16_to_cpu(usblp->dev->descriptor.idProduct);
                        if (copy_to_user((void __user *)arg,
                                        (unsigned char *)twoints,
                                        sizeof(twoints))) {
                                retval = -EFAULT;
                                goto done;
                        }

                        dev_dbg(&usblp->intf->dev,
                                "usblp%d is VID=0x%4.4X, PID=0x%4.4X\n",
                                usblp->minor, twoints[0], twoints[1]);
                        break;

                case IOCNR_SOFT_RESET:
                        if (_IOC_DIR(cmd) != _IOC_NONE) {
                                retval = -EINVAL;
                                goto done;
                        }
                        retval = usblp_reset(usblp);
                        break;
                default:
                        retval = -ENOTTY;
                }
        else    /* old-style ioctl value */
                switch (cmd) {

                case LPGETSTATUS:
                        retval = usblp_read_status(usblp, usblp->statusbuf);
                        if (retval) {
                                printk_ratelimited(KERN_ERR "usblp%d:"
                                            "failed reading printer status (%d)\n",
                                            usblp->minor, retval);
                                retval = -EIO;
                                goto done;
                        }
                        status = *usblp->statusbuf;
                        if (copy_to_user((void __user *)arg, &status, sizeof(int)))
                                retval = -EFAULT;
                        break;

                case LPABORT:
                        if (arg)
                                usblp->flags |= LP_ABORT;
                        else
                                usblp->flags &= ~LP_ABORT;
                        break;

                default:
                        retval = -ENOTTY;
                }

done:
        mutex_unlock(&usblp->mut);
        return retval;
}

static struct urb *usblp_new_writeurb(struct usblp *usblp, int transfer_length)
{
        struct urb *urb;
        char *writebuf;

        writebuf = kmalloc(transfer_length, GFP_KERNEL);
        if (writebuf == NULL)
                return NULL;
        urb = usb_alloc_urb(0, GFP_KERNEL);
        if (urb == NULL) {
                kfree(writebuf);
                return NULL;
        }

        usb_fill_bulk_urb(urb, usblp->dev,
                usb_sndbulkpipe(usblp->dev,
                 usblp->protocol[usblp->current_protocol].epwrite->bEndpointAddress),
                writebuf, transfer_length, usblp_bulk_write, usblp);
        urb->transfer_flags |= URB_FREE_BUFFER;

        return urb;
}

static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
{
        struct usblp *usblp = file->private_data;
        struct urb *writeurb;
        int rv;
        int transfer_length;
        ssize_t writecount = 0;

        if (mutex_lock_interruptible(&usblp->wmut)) {
                rv = -EINTR;
                goto raise_biglock;
        }
        if ((rv = usblp_wwait(usblp, !!(file->f_flags & O_NONBLOCK))) < 0)
                goto raise_wait;

        while (writecount < count) {
                /*
                 * Step 1: Submit next block.
                 */
                if ((transfer_length = count - writecount) > USBLP_BUF_SIZE)
                        transfer_length = USBLP_BUF_SIZE;

                rv = -ENOMEM;
                writeurb = usblp_new_writeurb(usblp, transfer_length);
                if (writeurb == NULL)
                        goto raise_urb;
                usb_anchor_urb(writeurb, &usblp->urbs);

                if (copy_from_user(writeurb->transfer_buffer,
                                   buffer + writecount, transfer_length)) {
                        rv = -EFAULT;
                        goto raise_badaddr;
                }

                spin_lock_irq(&usblp->lock);
                usblp->wcomplete = 0;
                spin_unlock_irq(&usblp->lock);
                if ((rv = usb_submit_urb(writeurb, GFP_KERNEL)) < 0) {
                        usblp->wstatus = 0;
                        spin_lock_irq(&usblp->lock);
                        usblp->no_paper = 0;
                        usblp->wcomplete = 1;
                        wake_up(&usblp->wwait);
                        spin_unlock_irq(&usblp->lock);
                        if (rv != -ENOMEM)
                                rv = -EIO;
                        goto raise_submit;
                }

                /*
                 * Step 2: Wait for transfer to end, collect results.
                 */
                rv = usblp_wwait(usblp, !!(file->f_flags&O_NONBLOCK));
                if (rv < 0) {
                        if (rv == -EAGAIN) {
                                /* Presume that it's going to complete well. */
                                writecount += transfer_length;
                        }
                        if (rv == -ENOSPC) {
                                spin_lock_irq(&usblp->lock);
                                usblp->no_paper = 1;    /* Mark for poll(2) */
                                spin_unlock_irq(&usblp->lock);
                                writecount += transfer_length;
                        }
                        /* Leave URB dangling, to be cleaned on close. */
                        goto collect_error;
                }

                if (usblp->wstatus < 0) {
                        rv = -EIO;
                        goto collect_error;
                }
                /*
                 * This is critical: it must be our URB, not other writer's.
                 * The wmut exists mainly to cover us here.
                 */
                writecount += usblp->wstatus;
        }

        mutex_unlock(&usblp->wmut);
        return writecount;

raise_submit:
raise_badaddr:
        usb_unanchor_urb(writeurb);
        usb_free_urb(writeurb);
raise_urb:
raise_wait:
collect_error:          /* Out of raise sequence */
        mutex_unlock(&usblp->wmut);
raise_biglock:
        return writecount ? writecount : rv;
}

/*
 * Notice that we fail to restart in a few cases: on EFAULT, on restart
 * error, etc. This is the historical behaviour. In all such cases we return
 * EIO, and applications loop in order to get the new read going.
 */
static ssize_t usblp_read(struct file *file, char __user *buffer, size_t len, loff_t *ppos)
{
        struct usblp *usblp = file->private_data;
        ssize_t count;
        ssize_t avail;
        int rv;

        if (!usblp->bidir)
                return -EINVAL;

        rv = usblp_rwait_and_lock(usblp, !!(file->f_flags & O_NONBLOCK));
        if (rv < 0)
                return rv;

        if ((avail = usblp->rstatus) < 0) {
                printk(KERN_ERR "usblp%d: error %d reading from printer\n",
                    usblp->minor, (int)avail);
                usblp_submit_read(usblp);
                count = -EIO;
                goto done;
        }

        count = len < avail - usblp->readcount ? len : avail - usblp->readcount;
        if (count != 0 &&
            copy_to_user(buffer, usblp->readbuf + usblp->readcount, count)) {
                count = -EFAULT;
                goto done;
        }

        if ((usblp->readcount += count) == avail) {
                if (usblp_submit_read(usblp) < 0) {
                        /* We don't want to leak USB return codes into errno. */
                        if (count == 0)
                                count = -EIO;
                        goto done;
                }
        }

done:
        mutex_unlock(&usblp->mut);
        return count;
}

/*
 * Wait for the write path to come idle.
 * This is called under the ->wmut, so the idle path stays idle.
 *
 * Our write path has a peculiar property: it does not buffer like a tty,
 * but waits for the write to succeed. This allows our ->release to bug out
 * without waiting for writes to drain. But it obviously does not work
 * when O_NONBLOCK is set. So, applications setting O_NONBLOCK must use
 * select(2) or poll(2) to wait for the buffer to drain before closing.
 * Alternatively, set blocking mode with fcntl and issue a zero-size write.
 */
static int usblp_wwait(struct usblp *usblp, int nonblock)
{
        DECLARE_WAITQUEUE(waita, current);
        int rc;
        int err = 0;

        add_wait_queue(&usblp->wwait, &waita);
        for (;;) {
                if (mutex_lock_interruptible(&usblp->mut)) {
                        rc = -EINTR;
                        break;
                }
                set_current_state(TASK_INTERRUPTIBLE);
                rc = usblp_wtest(usblp, nonblock);
                mutex_unlock(&usblp->mut);
                if (rc <= 0)
                        break;

                if (schedule_timeout(msecs_to_jiffies(1500)) == 0) {
                        if (usblp->flags & LP_ABORT) {
                                err = usblp_check_status(usblp, err);
                                if (err == 1) { /* Paper out */
                                        rc = -ENOSPC;
                                        break;
                                }
                        } else {
                                /* Prod the printer, Gentoo#251237. */
                                mutex_lock(&usblp->mut);
                                usblp_read_status(usblp, usblp->statusbuf);
                                mutex_unlock(&usblp->mut);
                        }
                }
        }
        set_current_state(TASK_RUNNING);
        remove_wait_queue(&usblp->wwait, &waita);
        return rc;
}

static int usblp_wtest(struct usblp *usblp, int nonblock)
{
        unsigned long flags;

        if (!usblp->present)
                return -ENODEV;
        if (signal_pending(current))
                return -EINTR;
        spin_lock_irqsave(&usblp->lock, flags);
        if (usblp->wcomplete) {
                spin_unlock_irqrestore(&usblp->lock, flags);
                return 0;
        }
        spin_unlock_irqrestore(&usblp->lock, flags);
        if (nonblock)
                return -EAGAIN;
        return 1;
}

/*
 * Wait for read bytes to become available. This probably should have been
 * called usblp_r_lock_and_wait(), because we lock first. But it's a traditional
 * name for functions which lock and return.
 *
 * We do not use wait_event_interruptible because it makes locking iffy.
 */
static int usblp_rwait_and_lock(struct usblp *usblp, int nonblock)
{
        DECLARE_WAITQUEUE(waita, current);
        int rc;

        add_wait_queue(&usblp->rwait, &waita);
        for (;;) {
                if (mutex_lock_interruptible(&usblp->mut)) {
                        rc = -EINTR;
                        break;
                }
                set_current_state(TASK_INTERRUPTIBLE);
                if ((rc = usblp_rtest(usblp, nonblock)) < 0) {
                        mutex_unlock(&usblp->mut);
                        break;
                }
                if (rc == 0)    /* Keep it locked */
                        break;
                mutex_unlock(&usblp->mut);
                schedule();
        }
        set_current_state(TASK_RUNNING);
        remove_wait_queue(&usblp->rwait, &waita);
        return rc;
}

static int usblp_rtest(struct usblp *usblp, int nonblock)
{
        unsigned long flags;

        if (!usblp->present)
                return -ENODEV;
        if (signal_pending(current))
                return -EINTR;
        spin_lock_irqsave(&usblp->lock, flags);
        if (usblp->rcomplete) {
                spin_unlock_irqrestore(&usblp->lock, flags);
                return 0;
        }
        spin_unlock_irqrestore(&usblp->lock, flags);
        if (nonblock)
                return -EAGAIN;
        return 1;
}

/*
 * Please check ->bidir and other such things outside for now.
 */
static int usblp_submit_read(struct usblp *usblp)
{
        struct urb *urb;
        unsigned long flags;
        int rc;

        rc = -ENOMEM;
        urb = usb_alloc_urb(0, GFP_KERNEL);
        if (urb == NULL)
                goto raise_urb;

        usb_fill_bulk_urb(urb, usblp->dev,
                usb_rcvbulkpipe(usblp->dev,
                  usblp->protocol[usblp->current_protocol].epread->bEndpointAddress),
                usblp->readbuf, USBLP_BUF_SIZE_IN,
                usblp_bulk_read, usblp);
        usb_anchor_urb(urb, &usblp->urbs);

        spin_lock_irqsave(&usblp->lock, flags);
        usblp->readcount = 0; /* XXX Why here? */
        usblp->rcomplete = 0;
        spin_unlock_irqrestore(&usblp->lock, flags);
        if ((rc = usb_submit_urb(urb, GFP_KERNEL)) < 0) {
                dev_dbg(&usblp->intf->dev, "error submitting urb (%d)\n", rc);
                spin_lock_irqsave(&usblp->lock, flags);
                usblp->rstatus = rc;
                usblp->rcomplete = 1;
                spin_unlock_irqrestore(&usblp->lock, flags);
                goto raise_submit;
        }

        return 0;

raise_submit:
        usb_unanchor_urb(urb);
        usb_free_urb(urb);
raise_urb:
        return rc;
}

/*
 * Checks for printers that have quirks, such as requiring unidirectional
 * communication but reporting bidirectional; currently some HP printers
 * have this flaw (HP 810, 880, 895, etc.), or needing an init string
 * sent at each open (like some Epsons).
 * Returns 1 if found, 0 if not found.
 *
 * HP recommended that we use the bidirectional interface but
 * don't attempt any bulk IN transfers from the IN endpoint.
 * Here's some more detail on the problem:
 * The problem is not that it isn't bidirectional though. The problem
 * is that if you request a device ID, or status information, while
 * the buffers are full, the return data will end up in the print data
 * buffer. For example if you make sure you never request the device ID
 * while you are sending print data, and you don't try to query the
 * printer status every couple of milliseconds, you will probably be OK.
 */
static unsigned int usblp_quirks(__u16 vendor, __u16 product)
{
        int i;

        for (i = 0; quirk_printers[i].vendorId; i++) {
                if (vendor == quirk_printers[i].vendorId &&
                    product == quirk_printers[i].productId)
                        return quirk_printers[i].quirks;
        }
        return 0;
}

static const struct file_operations usblp_fops = {
        .owner =        THIS_MODULE,
        .read =         usblp_read,
        .write =        usblp_write,
        .poll =         usblp_poll,
        .unlocked_ioctl =       usblp_ioctl,
        .compat_ioctl =         usblp_ioctl,
        .open =         usblp_open,
        .release =      usblp_release,
        .llseek =       noop_llseek,
};

static char *usblp_devnode(struct device *dev, umode_t *mode)
{
        return kasprintf(GFP_KERNEL, "usb/%s", dev_name(dev));
}

static struct usb_class_driver usblp_class = {
        .name =         "lp%d",
        .devnode =      usblp_devnode,
        .fops =         &usblp_fops,
        .minor_base =   USBLP_MINOR_BASE,
};

static ssize_t usblp_show_ieee1284_id(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct usb_interface *intf = to_usb_interface(dev);
        struct usblp *usblp = usb_get_intfdata(intf);

        if (usblp->device_id_string[0] == 0 &&
            usblp->device_id_string[1] == 0)
                return 0;

        return sprintf(buf, "%s", usblp->device_id_string+2);
}

static DEVICE_ATTR(ieee1284_id, S_IRUGO, usblp_show_ieee1284_id, NULL);

static int usblp_probe(struct usb_interface *intf,
                       const struct usb_device_id *id)
{
        struct usb_device *dev = interface_to_usbdev(intf);
        struct usblp *usblp;
        int protocol;
        int retval;

        /* Malloc and start initializing usblp structure so we can use it
         * directly. */
        usblp = kzalloc(sizeof(struct usblp), GFP_KERNEL);
        if (!usblp) {
                retval = -ENOMEM;
                goto abort_ret;
        }
        usblp->dev = dev;
        mutex_init(&usblp->wmut);
        mutex_init(&usblp->mut);
        spin_lock_init(&usblp->lock);
        init_waitqueue_head(&usblp->rwait);
        init_waitqueue_head(&usblp->wwait);
        init_usb_anchor(&usblp->urbs);
        usblp->ifnum = intf->cur_altsetting->desc.bInterfaceNumber;
        usblp->intf = intf;

        /* Malloc device ID string buffer to the largest expected length,
         * since we can re-query it on an ioctl and a dynamic string
         * could change in length. */
        if (!(usblp->device_id_string = kmalloc(USBLP_DEVICE_ID_SIZE, GFP_KERNEL))) {
                retval = -ENOMEM;
                goto abort;
        }

        /*
         * Allocate read buffer. We somewhat wastefully
         * malloc both regardless of bidirectionality, because the
         * alternate setting can be changed later via an ioctl.
         */
        if (!(usblp->readbuf = kmalloc(USBLP_BUF_SIZE_IN, GFP_KERNEL))) {
                retval = -ENOMEM;
                goto abort;
        }

        /* Allocate buffer for printer status */
        usblp->statusbuf = kmalloc(STATUS_BUF_SIZE, GFP_KERNEL);
        if (!usblp->statusbuf) {
                retval = -ENOMEM;
                goto abort;
        }

        /* Lookup quirks for this printer. */
        usblp->quirks = usblp_quirks(
                le16_to_cpu(dev->descriptor.idVendor),
                le16_to_cpu(dev->descriptor.idProduct));

        /* Analyze and pick initial alternate settings and endpoints. */
        protocol = usblp_select_alts(usblp);
        if (protocol < 0) {
                dev_dbg(&intf->dev,
                        "incompatible printer-class device 0x%4.4X/0x%4.4X\n",
                        le16_to_cpu(dev->descriptor.idVendor),
                        le16_to_cpu(dev->descriptor.idProduct));
                retval = -ENODEV;
                goto abort;
        }

        /* Setup the selected alternate setting and endpoints. */
        if (usblp_set_protocol(usblp, protocol) < 0) {
                retval = -ENODEV;       /* ->probe isn't ->ioctl */
                goto abort;
        }

        /* Retrieve and store the device ID string. */
        usblp_cache_device_id_string(usblp);
        retval = device_create_file(&intf->dev, &dev_attr_ieee1284_id);
        if (retval)
                goto abort_intfdata;

#ifdef DEBUG
        usblp_check_status(usblp, 0);
#endif

        usb_set_intfdata(intf, usblp);

        usblp->present = 1;

        retval = usb_register_dev(intf, &usblp_class);
        if (retval) {
                dev_err(&intf->dev,
                        "usblp: Not able to get a minor (base %u, slice default): %d\n",
                        USBLP_MINOR_BASE, retval);
                goto abort_intfdata;
        }
        usblp->minor = intf->minor;
        dev_info(&intf->dev,
                "usblp%d: USB %sdirectional printer dev %d if %d alt %d proto %d vid 0x%4.4X pid 0x%4.4X\n",
                usblp->minor, usblp->bidir ? "Bi" : "Uni", dev->devnum,
                usblp->ifnum,
                usblp->protocol[usblp->current_protocol].alt_setting,
                usblp->current_protocol,
                le16_to_cpu(usblp->dev->descriptor.idVendor),
                le16_to_cpu(usblp->dev->descriptor.idProduct));

        return 0;

abort_intfdata:
        usb_set_intfdata(intf, NULL);
        device_remove_file(&intf->dev, &dev_attr_ieee1284_id);
abort:
        kfree(usblp->readbuf);
        kfree(usblp->statusbuf);
        kfree(usblp->device_id_string);
        kfree(usblp);
abort_ret:
        return retval;
}

/*
 * We are a "new" style driver with usb_device_id table,
 * but our requirements are too intricate for simple match to handle.
 *
 * The "proto_bias" option may be used to specify the preferred protocol
 * for all USB printers (1=USB_CLASS_PRINTER/1/1, 2=USB_CLASS_PRINTER/1/2,
 * 3=USB_CLASS_PRINTER/1/3).  If the device supports the preferred protocol,
 * then we bind to it.
 *
 * The best interface for us is USB_CLASS_PRINTER/1/2, because it
 * is compatible with a stream of characters. If we find it, we bind to it.
 *
 * Note that the people from hpoj.sourceforge.net need to be able to
 * bind to USB_CLASS_PRINTER/1/3 (MLC/1284.4), so we provide them ioctls
 * for this purpose.
 *
 * Failing USB_CLASS_PRINTER/1/2, we look for USB_CLASS_PRINTER/1/3,
 * even though it's probably not stream-compatible, because this matches
 * the behaviour of the old code.
 *
 * If nothing else, we bind to USB_CLASS_PRINTER/1/1
 * - the unidirectional interface.
 */
static int usblp_select_alts(struct usblp *usblp)
{
        struct usb_interface *if_alt;
        struct usb_host_interface *ifd;
        struct usb_endpoint_descriptor *epd, *epwrite, *epread;
        int p, i, e;

        if_alt = usblp->intf;

        for (p = 0; p < USBLP_MAX_PROTOCOLS; p++)
                usblp->protocol[p].alt_setting = -1;

        /* Find out what we have. */
        for (i = 0; i < if_alt->num_altsetting; i++) {
                ifd = &if_alt->altsetting[i];

                if (ifd->desc.bInterfaceClass != USB_CLASS_PRINTER ||
                    ifd->desc.bInterfaceSubClass != 1)
                        if (!(usblp->quirks & USBLP_QUIRK_BAD_CLASS))
                                continue;

                if (ifd->desc.bInterfaceProtocol < USBLP_FIRST_PROTOCOL ||
                    ifd->desc.bInterfaceProtocol > USBLP_LAST_PROTOCOL)
                        continue;

                /* Look for bulk OUT and IN endpoints. */
                epwrite = epread = NULL;
                for (e = 0; e < ifd->desc.bNumEndpoints; e++) {
                        epd = &ifd->endpoint[e].desc;

                        if (usb_endpoint_is_bulk_out(epd))
                                if (!epwrite)
                                        epwrite = epd;

                        if (usb_endpoint_is_bulk_in(epd))
                                if (!epread)
                                        epread = epd;
                }

                /* Ignore buggy hardware without the right endpoints. */
                if (!epwrite || (ifd->desc.bInterfaceProtocol > 1 && !epread))
                        continue;

                /*
                 * Turn off reads for USB_CLASS_PRINTER/1/1 (unidirectional)
                 * interfaces and buggy bidirectional printers.
                 */
                if (ifd->desc.bInterfaceProtocol == 1) {
                        epread = NULL;
                } else if (usblp->quirks & USBLP_QUIRK_BIDIR) {
                        printk(KERN_INFO "usblp%d: Disabling reads from "
                            "problematic bidirectional printer\n",
                            usblp->minor);
                        epread = NULL;
                }

                usblp->protocol[ifd->desc.bInterfaceProtocol].alt_setting =
                                ifd->desc.bAlternateSetting;
                usblp->protocol[ifd->desc.bInterfaceProtocol].epwrite = epwrite;
                usblp->protocol[ifd->desc.bInterfaceProtocol].epread = epread;
        }

        /* If our requested protocol is supported, then use it. */
        if (proto_bias >= USBLP_FIRST_PROTOCOL &&
            proto_bias <= USBLP_LAST_PROTOCOL &&
            usblp->protocol[proto_bias].alt_setting != -1)
                return proto_bias;

        /* Ordering is important here. */
        if (usblp->protocol[2].alt_setting != -1)
                return 2;
        if (usblp->protocol[1].alt_setting != -1)
                return 1;
        if (usblp->protocol[3].alt_setting != -1)
                return 3;

        /* If nothing is available, then don't bind to this device. */
        return -1;
}

static int usblp_set_protocol(struct usblp *usblp, int protocol)
{
        int r, alts;

        if (protocol < USBLP_FIRST_PROTOCOL || protocol > USBLP_LAST_PROTOCOL)
                return -EINVAL;

        alts = usblp->protocol[protocol].alt_setting;
        if (alts < 0)
                return -EINVAL;
        r = usb_set_interface(usblp->dev, usblp->ifnum, alts);
        if (r < 0) {
                printk(KERN_ERR "usblp: can't set desired altsetting %d on interface %d\n",
                        alts, usblp->ifnum);
                return r;
        }

        usblp->bidir = (usblp->protocol[protocol].epread != NULL);
        usblp->current_protocol = protocol;
        dev_dbg(&usblp->intf->dev, "usblp%d set protocol %d\n",
                usblp->minor, protocol);
        return 0;
}

/* Retrieves and caches device ID string.
 * Returns length, including length bytes but not null terminator.
 * On error, returns a negative errno value. */
static int usblp_cache_device_id_string(struct usblp *usblp)
{
        int err, length;

        err = usblp_get_id(usblp, 0, usblp->device_id_string, USBLP_DEVICE_ID_SIZE - 1);
        if (err < 0) {
                dev_dbg(&usblp->intf->dev,
                        "usblp%d: error = %d reading IEEE-1284 Device ID string\n",
                        usblp->minor, err);
                usblp->device_id_string[0] = usblp->device_id_string[1] = '\0';
                return -EIO;
        }

        /* First two bytes are length in big-endian.
         * They count themselves, and we copy them into
         * the user's buffer. */
        length = be16_to_cpu(*((__be16 *)usblp->device_id_string));
        if (length < 2)
                length = 2;
        else if (length >= USBLP_DEVICE_ID_SIZE)
                length = USBLP_DEVICE_ID_SIZE - 1;
        usblp->device_id_string[length] = '\0';

        dev_dbg(&usblp->intf->dev, "usblp%d Device ID string [len=%d]=\"%s\"\n",
                usblp->minor, length, &usblp->device_id_string[2]);

        return length;
}

static void usblp_disconnect(struct usb_interface *intf)
{
        struct usblp *usblp = usb_get_intfdata(intf);

        usb_deregister_dev(intf, &usblp_class);

        if (!usblp || !usblp->dev) {
                dev_err(&intf->dev, "bogus disconnect\n");
                BUG();
        }

        device_remove_file(&intf->dev, &dev_attr_ieee1284_id);

        mutex_lock(&usblp_mutex);
        mutex_lock(&usblp->mut);
        usblp->present = 0;
        wake_up(&usblp->wwait);
        wake_up(&usblp->rwait);
        usb_set_intfdata(intf, NULL);

        usblp_unlink_urbs(usblp);
        mutex_unlock(&usblp->mut);

        if (!usblp->used)
                usblp_cleanup(usblp);
        mutex_unlock(&usblp_mutex);
}

static int usblp_suspend(struct usb_interface *intf, pm_message_t message)
{
        struct usblp *usblp = usb_get_intfdata(intf);

        usblp_unlink_urbs(usblp);
#if 0 /* XXX Do we want this? What if someone is reading, should we fail? */
        /* not strictly necessary, but just in case */
        wake_up(&usblp->wwait);
        wake_up(&usblp->rwait);
#endif

        return 0;
}

static int usblp_resume(struct usb_interface *intf)
{
        struct usblp *usblp = usb_get_intfdata(intf);
        int r;

        r = handle_bidir(usblp);

        return r;
}

static const struct usb_device_id usblp_ids[] = {
        { USB_DEVICE_INFO(USB_CLASS_PRINTER, 1, 1) },
        { USB_DEVICE_INFO(USB_CLASS_PRINTER, 1, 2) },
        { USB_DEVICE_INFO(USB_CLASS_PRINTER, 1, 3) },
        { USB_INTERFACE_INFO(USB_CLASS_PRINTER, 1, 1) },
        { USB_INTERFACE_INFO(USB_CLASS_PRINTER, 1, 2) },
        { USB_INTERFACE_INFO(USB_CLASS_PRINTER, 1, 3) },
        { USB_DEVICE(0x04b8, 0x0202) }, /* Seiko Epson Receipt Printer M129C */
        { }                                             /* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, usblp_ids);

static struct usb_driver usblp_driver = {
        .name =         "usblp",
        .probe =        usblp_probe,
        .disconnect =   usblp_disconnect,
        .suspend =      usblp_suspend,
        .resume =       usblp_resume,
        .id_table =     usblp_ids,
        .supports_autosuspend = 1,
};

module_usb_driver(usblp_driver);

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
module_param(proto_bias, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(proto_bias, "Favourite protocol number");
MODULE_LICENSE("GPL");