ClabureDB: Classified Bug-Reports Database

   /*
    * usblp.c
    *
    * Copyright (c) 1999 Michael Gee        <michael@linuxspecific.com>
    * Copyright (c) 1999 Pavel Machek        <pavel@suse.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_buffer_alloc() 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/init.h>
  #include <linux/slab.h>
  #include <linux/lp.h>
  #include <linux/mutex.h>
  #undef DEBUG
  #include <linux/usb.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=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)
  /* 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
          * (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, 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                sleeping;                /* interface is suspended */
         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) {
         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("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("wstatus=%d", usblp->wstatus);
         dbg("rstatus=%d", usblp->rstatus);
         dbg("quirks=%d", usblp->quirks);
         dbg("used=%d", usblp->used);
         dbg("bidir=%d", usblp->bidir);
         dbg("sleeping=%d", usblp->sleeping);
         dbg("device_id_string=\"%s\"",
                 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> */
         { 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);
         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;
         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);
                 if (printk_ratelimit())
                         printk(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 && !usblp->sleeping) {
                 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;
         }
 
         if (usblp->sleeping) {
                 retval = -ENODEV;
                 goto done;
         }
 
         dbg("usblp_ioctl: cmd=0x%x (%c nr=%d len=%d dir=%d)", 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;
                                 }
 
                                 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((void __user *)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] = 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;
                                 }
 
                                 dbg("usblp%d is VID=0x%4.4X, PID=0x%4.4X",
                                         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:
                                 if ((retval = usblp_read_status(usblp, usblp->statusbuf))) {
                                         if (printk_ratelimit())
                                                 printk(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;
 
         if ((writebuf = kmalloc(transfer_length, GFP_KERNEL)) == NULL)
                 return NULL;
         if ((urb = usb_alloc_urb(0, GFP_KERNEL)) == 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;
                 if ((writeurb = usblp_new_writeurb(usblp, transfer_length)) == 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 (;;) {
                 set_current_state(TASK_INTERRUPTIBLE);
                 if (mutex_lock_interruptible(&usblp->mut)) {
                         rc = -EINTR;
                         break;
                 }
                 rc = usblp_wtest(usblp, nonblock);
                 mutex_unlock(&usblp->mut);
                 if (rc <= 0)
                         break;
 
                 if (usblp->flags & LP_ABORT) {
                         if (schedule_timeout(msecs_to_jiffies(5000)) == 0) {
                                 err = usblp_check_status(usblp, err);
                                 if (err == 1) {        /* Paper out */
                                         rc = -ENOSPC;
                                         break;
                                 }
                         }
                 } else {
                         schedule();
                 }
         }
         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 (usblp->sleeping)
                 return -ENODEV;
         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 (usblp->sleeping)
                 return -ENODEV;
         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;
         if ((urb = usb_alloc_urb(0, GFP_KERNEL)) == 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) {
                 dbg("error submitting urb (%d)", 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,
};

static struct usb_class_driver usblp_class = {
        .name =                "lp%d",
        .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) {
                dbg("incompatible printer-class device 0x%4.4X/0x%4.4X",
                        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) {
                printk(KERN_ERR "usblp: Not able to get a minor"
                    " (base %u, slice default): %d\n",
                    USBLP_MINOR_BASE, retval);
                goto abort_intfdata;
        }
        usblp->minor = intf->minor;
        printk(KERN_INFO "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=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_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 != 7 || 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 7/1/1 (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;
        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 = 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';

        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_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);

        /* we take no more IO */
        usblp->sleeping = 1;
        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;

        usblp->sleeping = 0;
        r = handle_bidir (usblp);

        return r;
}

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) },
        { 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,
};

static int __init usblp_init(void)
{
        return usb_register(&usblp_driver);
}

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_param(proto_bias, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(proto_bias, "Favourite protocol number");
MODULE_LICENSE("GPL");