/*
 * printer.c  Version 0.13
 *
 * Copyright (c) 1999 Michael Gee       <michael@linuxspecific.com>
 * Copyright (c) 1999 Pavel Machek      <pavel@suse.cz>
 * Copyright (c) 2000 Randy Dunlap      <rddunlap@osdl.org>
 * Copyright (c) 2000 Vojtech Pavlik    <vojtech@suse.cz>
 # Copyright (c) 2001 Pete Zaitcev      <zaitcev@redhat.com>
 # Copyright (c) 2001 David Paschal     <paschal@rcsis.com>
 *
 * 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_buffer_alloc() for read buf & write buf;
 */

/*
 * 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/smp_lock.h>
#include <linux/signal.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/lp.h>
#include <linux/devfs_fs_kernel.h>
#undef DEBUG
#include <linux/usb.h>

/*
 * Version Information
 */
#define DRIVER_VERSION "v0.13"
#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_DEVICE_ID_SIZE    1024

/* ioctls: */
#define LPGETSTATUS             0x060b          /* same as in drivers/char/lp.c */
#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
/* 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=7/1/1, 2=7/1/2, 3=7/1/3),
 * [1]=supported protocol mask (mask&(1<<n)!=0 means 7/1/n supported): */
#define LPIOC_GET_PROTOCOLS(len) _IOC(_IOC_READ, 'P', IOCNR_GET_PROTOCOLS, len)
/* Set protocol (arg: 1=7/1/1, 2=7/1/2, 3=7/1/3): */
#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)

/*
 * 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_WRITE_TIMEOUT     (5*HZ)                  /* 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

struct usblp {
        struct usb_device       *dev;                   /* USB device */
        devfs_handle_t          devfs;                  /* devfs device */
        struct semaphore        sem;                    /* locks this struct, especially "dev" */
        char                    *writebuf;              /* write transfer_buffer */
        char                    *readbuf;               /* read transfer_buffer */
        char                    *statusbuf;             /* status transfer_buffer */
        struct urb              *readurb, *writeurb;    /* The urbs */
        wait_queue_head_t       wait;                   /* Zzzzz ... */
        int                     readcount;              /* Counter for reads */
        int                     ifnum;                  /* Interface number */
        /* Alternate-setting numbers and endpoints for each protocol
         * (7/1/{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;              /* writing is completed */
        int                     rcomplete;              /* reading is completed */
        unsigned int            quirks;                 /* quirks flags */
        unsigned char           used;                   /* True if open */
        unsigned char           present;                /* True if not disconnected */
        unsigned char           bidir;                  /* interface is bidirectional */
        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) {
        int p;

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

extern devfs_handle_t usb_devfs_handle;                 /* /dev/usb dir. */

static struct usblp *usblp_table[USBLP_MINORS];

/* 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 */

static 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) */
        { 0, 0 }
};

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);

static DECLARE_MUTEX(usblp_sem);        /* 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_WRITE_TIMEOUT);
        dbg("usblp_control_msg: rq: 0x%02x dir: %d recip: %d value: %d idx: %d len: %#x result: %d",
                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;

        if (!usblp || !usblp->dev || !usblp->used || !usblp->present)
                return;

        if (unlikely(urb->status))
                warn("usblp%d: nonzero read/write bulk status received: %d",
                        usblp->minor, urb->status);
        usblp->rcomplete = 1;
        wake_up_interruptible(&usblp->wait);
}

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

        if (!usblp || !usblp->dev || !usblp->used || !usblp->present)
                return;

        if (unlikely(urb->status))
                warn("usblp%d: nonzero read/write bulk status received: %d",
                        usblp->minor, urb->status);
        usblp->wcomplete = 1;
        wake_up_interruptible(&usblp->wait);
}

/*
 * Get and print printer errors.
 */

static 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;

        error = usblp_read_status (usblp, usblp->statusbuf);
        if (error < 0) {
                err("usblp%d: error %d reading printer status",
                        usblp->minor, error);
                return 0;
        }

        status = *usblp->statusbuf;

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

        if (newerr != err)
                info("usblp%d: %s", usblp->minor, usblp_messages[newerr]);

        return newerr;
}

/*
 * File op functions.
 */

static int usblp_open(struct inode *inode, struct file *file)
{
        int minor = MINOR(inode->i_rdev) - USBLP_MINOR_BASE;
        struct usblp *usblp;
        int retval;

        if (minor < 0 || minor >= USBLP_MINORS)
                return -ENODEV;

        down (&usblp_sem);
        usblp  = usblp_table[minor];

        retval = -ENODEV;
        if (!usblp || !usblp->dev || !usblp->present)
                goto out;

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

        /*
         * TODO: need to implement LP_ABORTOPEN + O_NONBLOCK as in drivers/char/lp.c ???
         * This is #if 0-ed because we *don't* want to fail an open
         * just because the printer is off-line.
         */
#if 0
        if ((retval = usblp_check_status(usblp, 0))) {
                retval = retval > 1 ? -EIO : -ENOSPC;
                goto out;
        }
#else
        retval = 0;
#endif

        usblp->used = 1;
        file->private_data = usblp;

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

        if (usblp->bidir) {
                usblp->readcount = 0;
                usblp->readurb->dev = usblp->dev;
                if (usb_submit_urb(usblp->readurb) < 0) {
                        retval = -EIO;
                        usblp->used = 0;
                        file->private_data = NULL;
                }
        }
out:
        up (&usblp_sem);
        return retval;
}

static void usblp_cleanup (struct usblp *usblp)
{
        devfs_unregister (usblp->devfs);
        usblp_table [usblp->minor] = NULL;
        info("usblp%d: removed", usblp->minor);

        kfree (usblp->writebuf);
        kfree (usblp->readbuf);
        kfree (usblp->device_id_string);
        kfree (usblp->statusbuf);
        usb_free_urb(usblp->writeurb);
        usb_free_urb(usblp->readurb);
        kfree (usblp);
}

static void usblp_unlink_urbs(struct usblp *usblp)
{
        usb_unlink_urb(usblp->writeurb);
        if (usblp->bidir)
                usb_unlink_urb(usblp->readurb);
}

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

        down (&usblp_sem);
        usblp->used = 0;
        if (usblp->present) {
                usblp_unlink_urbs(usblp);
        } else          /* finish cleanup from disconnect */
                usblp_cleanup (usblp);
        up (&usblp_sem);
        return 0;
}

/* No kernel lock - fine */
static unsigned int usblp_poll(struct file *file, struct poll_table_struct *wait)
{
        struct usblp *usblp = file->private_data;
        poll_wait(file, &usblp->wait, wait);
        return ((!usblp->bidir || !usblp->rcomplete) ? 0 : POLLIN  | POLLRDNORM)
                               | (!usblp->wcomplete ? 0 : POLLOUT | POLLWRNORM);
}

static int usblp_ioctl(struct inode *inode, 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;

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

        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((unsigned char *) 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((unsigned char *)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 ||
                                    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) {
                                        err("usblp%d: error = %d setting "
                                                "HP channel",
                                                usblp->minor, err);
                                        retval = -EIO;
                                        goto done;
                                }

                                dbg("usblp%d requested/got HP channel %ld/%d",
                                        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((unsigned char *)arg,
                                                (unsigned char *)twoints,
                                                sizeof(twoints))) {
                                        retval = -EFAULT;
                                        goto done;
                                }

                                dbg("usblp%d is bus=%d, device=%d",
                                        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] = usblp->dev->descriptor.idVendor;
                                twoints[1] = usblp->dev->descriptor.idProduct;
                                if (copy_to_user((unsigned char *)arg,
                                                (unsigned char *)twoints,
                                                sizeof(twoints))) {
                                        retval = -EFAULT;
                                        goto done;
                                }

                                dbg("usblp%d is VID=0x%4.4X, PID=0x%4.4X",
                                        usblp->minor, twoints[0], twoints[1]);
                                break;

                        default:
                                retval = -ENOTTY;
                }
        else    /* old-style ioctl value */
                switch (cmd) {

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

                        default:
                                retval = -ENOTTY;
                }

done:
        up (&usblp->sem);
        return retval;
}

static ssize_t usblp_write(struct file *file, const char *buffer, size_t count, loff_t *ppos)
{
        DECLARE_WAITQUEUE(wait, current);
        struct usblp *usblp = file->private_data;
        int timeout, err = 0, transfer_length = 0;
        size_t writecount = 0;

        while (writecount < count) {
                if (!usblp->wcomplete) {
                        barrier();
                        if (file->f_flags & O_NONBLOCK) {
                                writecount += transfer_length;
                                return writecount ? writecount : -EAGAIN;
                        }

                        timeout = USBLP_WRITE_TIMEOUT;
                        add_wait_queue(&usblp->wait, &wait);
                        while ( 1==1 ) {

                                if (signal_pending(current)) {
                                        remove_wait_queue(&usblp->wait, &wait);
                                        return writecount ? writecount : -EINTR;
                                }
                                set_current_state(TASK_INTERRUPTIBLE);
                                if (timeout && !usblp->wcomplete) {
                                        timeout = schedule_timeout(timeout);
                                } else {
                                        set_current_state(TASK_RUNNING);
                                        break;
                                }
                        }
                        remove_wait_queue(&usblp->wait, &wait);
                }

                down (&usblp->sem);
                if (!usblp->present) {
                        up (&usblp->sem);
                        return -ENODEV;
                }

                if (usblp->writeurb->status != 0) {
                        if (usblp->quirks & USBLP_QUIRK_BIDIR) {
                                if (!usblp->wcomplete)
                                        err("usblp%d: error %d writing to printer",
                                                usblp->minor, usblp->writeurb->status);
                                err = usblp->writeurb->status;
                        } else
                                err = usblp_check_status(usblp, err);
                        up (&usblp->sem);

                        /* if the fault was due to disconnect, let khubd's
                         * call to usblp_disconnect() grab usblp->sem ...
                         */
                        schedule ();
                        continue;
                }

                /* We must increment writecount here, and not at the
                 * end of the loop. Otherwise, the final loop iteration may
                 * be skipped, leading to incomplete printer output.
                 */
                writecount += transfer_length;
                if (writecount == count) {
                        up (&usblp->sem);
                        break;
                }

                transfer_length = count - writecount;
                if(transfer_length > USBLP_BUF_SIZE) 
                        transfer_length = USBLP_BUF_SIZE;
                
                usblp->writeurb->transfer_buffer_length = transfer_length;

                if (copy_from_user(usblp->writeurb->transfer_buffer, 
                                   buffer + writecount, transfer_length)) {
                        up(&usblp->sem);
                        return writecount ? writecount : -EFAULT;
                }

                usblp->writeurb->dev = usblp->dev;
                usblp->wcomplete = 0;
                err = usb_submit_urb(usblp->writeurb);
                if (err) {
                        if (err != -ENOMEM)
                                count = -EIO;
                        else
                                count = writecount ? writecount : -ENOMEM;
                        up (&usblp->sem);
                        break;
                }
                up (&usblp->sem);
        }

        return count;
}

static ssize_t usblp_read(struct file *file, char *buffer, size_t count, loff_t *ppos)
{
        struct usblp *usblp = file->private_data;
        DECLARE_WAITQUEUE(wait, current);

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

        down (&usblp->sem);
        if (!usblp->present) {
                count = -ENODEV;
                goto done;
        }

        if (!usblp->rcomplete) {
                barrier();

                if (file->f_flags & O_NONBLOCK) {
                        count = -EAGAIN;
                        goto done;
                }

                add_wait_queue(&usblp->wait, &wait);
                while (1==1) {
                        if (signal_pending(current)) {
                                count = -EINTR;
                                remove_wait_queue(&usblp->wait, &wait);
                                goto done;
                        }
                        up (&usblp->sem);
                        set_current_state(TASK_INTERRUPTIBLE);
                        if (!usblp->rcomplete) {
                                schedule();
                        } else {
                                set_current_state(TASK_RUNNING);
                                break;
                        }
                        down (&usblp->sem);
                }
                remove_wait_queue(&usblp->wait, &wait);
        }

        if (!usblp->present) {
                count = -ENODEV;
                goto done;
        }

        if (usblp->readurb->status) {
                err("usblp%d: error %d reading from printer",
                        usblp->minor, usblp->readurb->status);
                usblp->readurb->dev = usblp->dev;
                usblp->readcount = 0;
                usblp->rcomplete = 0;
                if (usb_submit_urb(usblp->readurb) < 0)
                        dbg("error submitting urb");
                count = -EIO;
                goto done;
        }

        count = count < usblp->readurb->actual_length - usblp->readcount ?
                count : usblp->readurb->actual_length - usblp->readcount;

        if (copy_to_user(buffer, usblp->readurb->transfer_buffer + usblp->readcount, count)) {
                count = -EFAULT;
                goto done;
        }

        if ((usblp->readcount += count) == usblp->readurb->actual_length) {
                usblp->readcount = 0;
                usblp->readurb->dev = usblp->dev;
                usblp->rcomplete = 0;
                if (usb_submit_urb(usblp->readurb)) {
                        count = -EIO;
                        goto done;
                }
        }

done:
        up (&usblp->sem);
        return count;
}

/*
 * 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 struct file_operations usblp_fops = {
        owner:          THIS_MODULE,
        read:           usblp_read,
        write:          usblp_write,
        poll:           usblp_poll,
        ioctl:          usblp_ioctl,
        open:           usblp_open,
        release:        usblp_release,
};

static void *usblp_probe(struct usb_device *dev, unsigned int ifnum,
                         const struct usb_device_id *id)
{
        struct usblp *usblp = 0;
        int protocol;
        char name[6];

        /* Malloc and start initializing usblp structure so we can use it
         * directly. */
        if (!(usblp = kmalloc(sizeof(struct usblp), GFP_KERNEL))) {
                err("out of memory for usblp");
                goto abort;
        }
        memset(usblp, 0, sizeof(struct usblp));
        usblp->dev = dev;
        init_MUTEX (&usblp->sem);
        init_waitqueue_head(&usblp->wait);
        usblp->ifnum = ifnum;

        /* Look for a free usblp_table entry. */
        while (usblp_table[usblp->minor]) {
                usblp->minor++;
                if (usblp->minor >= USBLP_MINORS) {
                        err("no more free usblp devices");
                        goto abort;
                }
        }

        usblp->writeurb = usb_alloc_urb(0);
        if (!usblp->writeurb) {
                err("out of memory");
                goto abort;
        }
        usblp->readurb = usb_alloc_urb(0);
        if (!usblp->readurb) {
                err("out of memory");
                goto abort;
        }

        /* 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))) {
                err("out of memory for device_id_string");
                goto abort;
        }

        usblp->writebuf = usblp->readbuf = NULL;
        /* Malloc write & read buffers.  We somewhat wastefully
         * malloc both regardless of bidirectionality, because the
         * alternate setting can be changed later via an ioctl. */
        if (!(usblp->writebuf = kmalloc(USBLP_BUF_SIZE, GFP_KERNEL))) {
                err("out of memory for write buf");
                goto abort;
        }
        if (!(usblp->readbuf = kmalloc(USBLP_BUF_SIZE, GFP_KERNEL))) {
                err("out of memory for read buf");
                goto abort;
        }

        /* Allocate buffer for printer status */
        usblp->statusbuf = kmalloc(STATUS_BUF_SIZE, GFP_KERNEL);
        if (!usblp->statusbuf) {
                err("out of memory for statusbuf");
                goto abort;
        }

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

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

        /* Setup the selected alternate setting and endpoints. */
        if (usblp_set_protocol(usblp, protocol) < 0)
                goto abort;

        /* Retrieve and store the device ID string. */
        usblp_cache_device_id_string(usblp);

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

        usblp_table[usblp->minor] = usblp;
        /* If we have devfs, create with perms=660. */
        sprintf(name, "lp%d", usblp->minor);
        usblp->devfs = devfs_register(usb_devfs_handle, name,
                                      DEVFS_FL_DEFAULT, USB_MAJOR,
                                      USBLP_MINOR_BASE + usblp->minor,
                                      S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP |
                                      S_IWGRP, &usblp_fops, NULL);

        info("usblp%d: USB %sdirectional printer dev %d "
                "if %d alt %d proto %d vid 0x%4.4X pid 0x%4.4X",
                usblp->minor, usblp->bidir ? "Bi" : "Uni", dev->devnum,
                usblp->ifnum,
                usblp->protocol[usblp->current_protocol].alt_setting,
                usblp->current_protocol, usblp->dev->descriptor.idVendor,
                usblp->dev->descriptor.idProduct);

        usblp->present = 1;

        return usblp;

abort:
        if (usblp) {
                if (usblp->writebuf)
                        kfree (usblp->writebuf);
                if (usblp->readbuf)
                        kfree (usblp->readbuf);
                kfree(usblp->statusbuf);
                kfree(usblp->device_id_string);
                usb_free_urb(usblp->writeurb);
                usb_free_urb(usblp->readurb);
                kfree(usblp);
        }
        return NULL;
}

/*
 * 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=7/1/1, 2=7/1/2, 3=7/1/3).  If the device
 * supports the preferred protocol, then we bind to it.
 *
 * The best interface for us is 7/1/2, 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 7/1/3 (MLC/1284.4), so we provide them ioctls for this purpose.
 *
 * Failing 7/1/2, we look for 7/1/3, even though it's probably not
 * stream-compatible, because this matches the behaviour of the old code.
 *
 * If nothing else, we bind to 7/1/1 - the unidirectional interface.
 */
static int usblp_select_alts(struct usblp *usblp)
{
        struct usb_interface *if_alt;
        struct usb_interface_descriptor *ifd;
        struct usb_endpoint_descriptor *epd, *epwrite, *epread;
        int p, i, e;

        if_alt = &usblp->dev->actconfig->interface[usblp->ifnum];

        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->bInterfaceClass != 7 || ifd->bInterfaceSubClass != 1)
                        continue;

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

                /* Look for bulk OUT and IN endpoints. */
                epwrite = epread = 0;

                for (e = 0; e < ifd->bNumEndpoints; e++) {
                        epd = &ifd->endpoint[e];

                        if ((epd->bmAttributes&USB_ENDPOINT_XFERTYPE_MASK)!=
                            USB_ENDPOINT_XFER_BULK)
                                continue;

                        if (!(epd->bEndpointAddress & USB_ENDPOINT_DIR_MASK)) {
                                if (!epwrite) epwrite=epd;

                        } else {
                                if (!epread) epread=epd;
                        }
                }

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

                /* Turn off reads for 7/1/1 (unidirectional) interfaces
                 * and buggy bidirectional printers. */
                if (ifd->bInterfaceProtocol == 1) {
                        epread = NULL;
                } else if (usblp->quirks & USBLP_QUIRK_BIDIR) {
                        info("Disabling reads from problem bidirectional "
                                "printer on usblp%d", usblp->minor);
                        epread = NULL;
                }

                usblp->protocol[ifd->bInterfaceProtocol].alt_setting = i;
                usblp->protocol[ifd->bInterfaceProtocol].epwrite = epwrite;
                usblp->protocol[ifd->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) {
                err("can't set desired altsetting %d on interface %d",
                        alts, usblp->ifnum);
                return r;
        }

        usb_fill_bulk_urb(usblp->writeurb, usblp->dev,
                usb_sndbulkpipe(usblp->dev,
                  usblp->protocol[protocol].epwrite->bEndpointAddress),
                usblp->writebuf, 0,
                usblp_bulk_write, usblp);

        usblp->bidir = (usblp->protocol[protocol].epread != 0);
        if (usblp->bidir)
                usb_fill_bulk_urb(usblp->readurb, usblp->dev,
                        usb_rcvbulkpipe(usblp->dev,
                          usblp->protocol[protocol].epread->bEndpointAddress),
                        usblp->readbuf, USBLP_BUF_SIZE,
                        usblp_bulk_read, usblp);

        usblp->current_protocol = protocol;
        dbg("usblp%d set protocol %d", 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) {
                dbg("usblp%d: error = %d reading IEEE-1284 Device ID string",
                        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 = (usblp->device_id_string[0] << 8) + usblp->device_id_string[1];
        if (length < 2)
                length = 2;
        else if (length >= USBLP_DEVICE_ID_SIZE)
                length = USBLP_DEVICE_ID_SIZE - 1;
        usblp->device_id_string[length] = '\0';

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

        return length;
}

static void usblp_disconnect(struct usb_device *dev, void *ptr)
{
        struct usblp *usblp = ptr;

        if (!usblp || !usblp->dev) {
                err("bogus disconnect");
                BUG ();
        }

        down (&usblp_sem);
        down (&usblp->sem);
        usblp->present = 0;

        usblp_unlink_urbs(usblp);
        up (&usblp->sem);

        if (!usblp->used)
                usblp_cleanup (usblp);
        up (&usblp_sem);
}

static struct usb_device_id usblp_ids [] = {
        { USB_DEVICE_INFO(7, 1, 1) },
        { USB_DEVICE_INFO(7, 1, 2) },
        { USB_DEVICE_INFO(7, 1, 3) },
        { USB_INTERFACE_INFO(7, 1, 1) },
        { USB_INTERFACE_INFO(7, 1, 2) },
        { USB_INTERFACE_INFO(7, 1, 3) },
        { }                                             /* Terminating entry */
};

MODULE_DEVICE_TABLE (usb, usblp_ids);

static struct usb_driver usblp_driver = {
        name:           "usblp",
        probe:          usblp_probe,
        disconnect:     usblp_disconnect,
        fops:           &usblp_fops,
        minor:          USBLP_MINOR_BASE,
        id_table:       usblp_ids,
};

static int __init usblp_init(void)
{
        if (usb_register(&usblp_driver))
                return -1;
        info(DRIVER_VERSION ": " DRIVER_DESC);
        return 0;
}

static void __exit usblp_exit(void)
{
        usb_deregister(&usblp_driver);
}

module_init(usblp_init);
module_exit(usblp_exit);

MODULE_AUTHOR( DRIVER_AUTHOR );
MODULE_DESCRIPTION( DRIVER_DESC );
MODULE_PARM(proto_bias, "i");
MODULE_PARM_DESC(proto_bias, "Favourite protocol number");
MODULE_LICENSE("GPL");