drivers/usb/misc/legousbtower.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * LEGO USB Tower driver
   4  *
   5  * Copyright (C) 2003 David Glance <davidgsf@sourceforge.net>
   6  *               2001-2004 Juergen Stuber <starblue@users.sourceforge.net>
   7  *
   8  * derived from USB Skeleton driver - 0.5
   9  * Copyright (C) 2001 Greg Kroah-Hartman (greg@kroah.com)
  10  *
  11  * History:
  12  *
  13  * 2001-10-13 - 0.1 js
  14  *   - first version
  15  * 2001-11-03 - 0.2 js
  16  *   - simplified buffering, one-shot URBs for writing
  17  * 2001-11-10 - 0.3 js
  18  *   - removed IOCTL (setting power/mode is more complicated, postponed)
  19  * 2001-11-28 - 0.4 js
  20  *   - added vendor commands for mode of operation and power level in open
  21  * 2001-12-04 - 0.5 js
  22  *   - set IR mode by default (by oversight 0.4 set VLL mode)
  23  * 2002-01-11 - 0.5? pcchan
  24  *   - make read buffer reusable and work around bytes_to_write issue between
  25  *     uhci and legusbtower
  26  * 2002-09-23 - 0.52 david (david@csse.uwa.edu.au)
  27  *   - imported into lejos project
  28  *   - changed wake_up to wake_up_interruptible
  29  *   - changed to use lego0 rather than tower0
  30  *   - changed dbg() to use __func__ rather than deprecated __func__
  31  * 2003-01-12 - 0.53 david (david@csse.uwa.edu.au)
  32  *   - changed read and write to write everything or
  33  *     timeout (from a patch by Chris Riesen and Brett Thaeler driver)
  34  *   - added ioctl functionality to set timeouts
  35  * 2003-07-18 - 0.54 davidgsf (david@csse.uwa.edu.au)
  36  *   - initial import into LegoUSB project
  37  *   - merge of existing LegoUSB.c driver
  38  * 2003-07-18 - 0.56 davidgsf (david@csse.uwa.edu.au)
  39  *   - port to 2.6 style driver
  40  * 2004-02-29 - 0.6 Juergen Stuber <starblue@users.sourceforge.net>
  41  *   - fix locking
  42  *   - unlink read URBs which are no longer needed
  43  *   - allow increased buffer size, eliminates need for timeout on write
  44  *   - have read URB running continuously
  45  *   - added poll
  46  *   - forbid seeking
  47  *   - added nonblocking I/O
  48  *   - changed back __func__ to __func__
  49  *   - read and log tower firmware version
  50  *   - reset tower on probe, avoids failure of first write
  51  * 2004-03-09 - 0.7 Juergen Stuber <starblue@users.sourceforge.net>
  52  *   - timeout read now only after inactivity, shorten default accordingly
  53  * 2004-03-11 - 0.8 Juergen Stuber <starblue@users.sourceforge.net>
  54  *   - log major, minor instead of possibly confusing device filename
  55  *   - whitespace cleanup
  56  * 2004-03-12 - 0.9 Juergen Stuber <starblue@users.sourceforge.net>
  57  *   - normalize whitespace in debug messages
  58  *   - take care about endianness in control message responses
  59  * 2004-03-13 - 0.91 Juergen Stuber <starblue@users.sourceforge.net>
  60  *   - make default intervals longer to accommodate current EHCI driver
  61  * 2004-03-19 - 0.92 Juergen Stuber <starblue@users.sourceforge.net>
  62  *   - replaced atomic_t by memory barriers
  63  * 2004-04-21 - 0.93 Juergen Stuber <starblue@users.sourceforge.net>
  64  *   - wait for completion of write urb in release (needed for remotecontrol)
  65  *   - corrected poll for write direction (missing negation)
  66  * 2004-04-22 - 0.94 Juergen Stuber <starblue@users.sourceforge.net>
  67  *   - make device locking interruptible
  68  * 2004-04-30 - 0.95 Juergen Stuber <starblue@users.sourceforge.net>
  69  *   - check for valid udev on resubmitting and unlinking urbs
  70  * 2004-08-03 - 0.96 Juergen Stuber <starblue@users.sourceforge.net>
  71  *   - move reset into open to clean out spurious data
  72  */
  73
  74 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  75
  76 #include <linux/kernel.h>
  77 #include <linux/errno.h>
  78 #include <linux/slab.h>
  79 #include <linux/module.h>
  80 #include <linux/completion.h>
  81 #include <linux/mutex.h>
  82 #include <linux/uaccess.h>
  83 #include <linux/usb.h>
  84 #include <linux/poll.h>
  85
  86
  87 #define DRIVER_AUTHOR "Juergen Stuber <starblue@sourceforge.net>"
  88 #define DRIVER_DESC "LEGO USB Tower Driver"
  89
  90
  91 /* The defaults are chosen to work with the latest versions of leJOS and NQC.
  92  */
  93
  94 /* Some legacy software likes to receive packets in one piece.
  95  * In this case read_buffer_size should exceed the maximal packet length
  96  * (417 for datalog uploads), and packet_timeout should be set.
  97  */
  98 static int read_buffer_size = 480;
  99 module_param(read_buffer_size, int, 0);
 100 MODULE_PARM_DESC(read_buffer_size, "Read buffer size");
 101
 102 /* Some legacy software likes to send packets in one piece.
 103  * In this case write_buffer_size should exceed the maximal packet length
 104  * (417 for firmware and program downloads).
 105  * A problem with long writes is that the following read may time out
 106  * if the software is not prepared to wait long enough.
 107  */
 108 static int write_buffer_size = 480;
 109 module_param(write_buffer_size, int, 0);
 110 MODULE_PARM_DESC(write_buffer_size, "Write buffer size");
 111
 112 /* Some legacy software expects reads to contain whole LASM packets.
 113  * To achieve this, characters which arrive before a packet timeout
 114  * occurs will be returned in a single read operation.
 115  * A problem with long reads is that the software may time out
 116  * if it is not prepared to wait long enough.
 117  * The packet timeout should be greater than the time between the
 118  * reception of subsequent characters, which should arrive about
 119  * every 5ms for the standard 2400 baud.
 120  * Set it to 0 to disable.
 121  */
 122 static int packet_timeout = 50;
 123 module_param(packet_timeout, int, 0);
 124 MODULE_PARM_DESC(packet_timeout, "Packet timeout in ms");
 125
 126 /* Some legacy software expects blocking reads to time out.
 127  * Timeout occurs after the specified time of read and write inactivity.
 128  * Set it to 0 to disable.
 129  */
 130 static int read_timeout = 200;
 131 module_param(read_timeout, int, 0);
 132 MODULE_PARM_DESC(read_timeout, "Read timeout in ms");
 133
 134 /* As of kernel version 2.6.4 ehci-hcd uses an
 135  * "only one interrupt transfer per frame" shortcut
 136  * to simplify the scheduling of periodic transfers.
 137  * This conflicts with our standard 1ms intervals for in and out URBs.
 138  * We use default intervals of 2ms for in and 8ms for out transfers,
 139  * which is fast enough for 2400 baud and allows a small additional load.
 140  * Increase the interval to allow more devices that do interrupt transfers,
 141  * or set to 0 to use the standard interval from the endpoint descriptors.
 142  */
 143 static int interrupt_in_interval = 2;
 144 module_param(interrupt_in_interval, int, 0);
 145 MODULE_PARM_DESC(interrupt_in_interval, "Interrupt in interval in ms");
 146
 147 static int interrupt_out_interval = 8;
 148 module_param(interrupt_out_interval, int, 0);
 149 MODULE_PARM_DESC(interrupt_out_interval, "Interrupt out interval in ms");
 150
 151 /* Define these values to match your device */
 152 #define LEGO_USB_TOWER_VENDOR_ID        0x0694
 153 #define LEGO_USB_TOWER_PRODUCT_ID       0x0001
 154
 155 /* Vendor requests */
 156 #define LEGO_USB_TOWER_REQUEST_RESET            0x04
 157 #define LEGO_USB_TOWER_REQUEST_GET_VERSION      0xFD
 158
 159 struct tower_reset_reply {
 160         __le16 size;            /* little-endian */
 161         __u8 err_code;
 162         __u8 spare;
 163 } __attribute__ ((packed));
 164
 165 struct tower_get_version_reply {
 166         __le16 size;            /* little-endian */
 167         __u8 err_code;
 168         __u8 spare;
 169         __u8 major;
 170         __u8 minor;
 171         __le16 build_no;                /* little-endian */
 172 } __attribute__ ((packed));
 173
 174
 175 /* table of devices that work with this driver */
 176 static const struct usb_device_id tower_table[] = {
 177         { USB_DEVICE(LEGO_USB_TOWER_VENDOR_ID, LEGO_USB_TOWER_PRODUCT_ID) },
 178         { }                                     /* Terminating entry */
 179 };
 180
 181 MODULE_DEVICE_TABLE (usb, tower_table);
 182
 183 #define LEGO_USB_TOWER_MINOR_BASE       160
 184
 185
 186 /* Structure to hold all of our device specific stuff */
 187 struct lego_usb_tower {
 188         struct mutex            lock;           /* locks this structure */
 189         struct usb_device*      udev;           /* save off the usb device pointer */
 190         unsigned char           minor;          /* the starting minor number for this device */
 191
 192         int                     open_count;     /* number of times this port has been opened */
 193         unsigned long           disconnected:1;
 194
 195         char*                   read_buffer;
 196         size_t                  read_buffer_length; /* this much came in */
 197         size_t                  read_packet_length; /* this much will be returned on read */
 198         spinlock_t              read_buffer_lock;
 199         int                     packet_timeout_jiffies;
 200         unsigned long           read_last_arrival;
 201
 202         wait_queue_head_t       read_wait;
 203         wait_queue_head_t       write_wait;
 204
 205         char*                   interrupt_in_buffer;
 206         struct usb_endpoint_descriptor* interrupt_in_endpoint;
 207         struct urb*             interrupt_in_urb;
 208         int                     interrupt_in_interval;
 209         int                     interrupt_in_running;
 210         int                     interrupt_in_done;
 211
 212         char*                   interrupt_out_buffer;
 213         struct usb_endpoint_descriptor* interrupt_out_endpoint;
 214         struct urb*             interrupt_out_urb;
 215         int                     interrupt_out_interval;
 216         int                     interrupt_out_busy;
 217
 218 };
 219
 220
 221 /* local function prototypes */
 222 static ssize_t tower_read       (struct file *file, char __user *buffer, size_t count, loff_t *ppos);
 223 static ssize_t tower_write      (struct file *file, const char __user *buffer, size_t count, loff_t *ppos);
 224 static inline void tower_delete (struct lego_usb_tower *dev);
 225 static int tower_open           (struct inode *inode, struct file *file);
 226 static int tower_release        (struct inode *inode, struct file *file);
 227 static __poll_t tower_poll      (struct file *file, poll_table *wait);
 228 static loff_t tower_llseek      (struct file *file, loff_t off, int whence);
 229
 230 static void tower_abort_transfers (struct lego_usb_tower *dev);
 231 static void tower_check_for_read_packet (struct lego_usb_tower *dev);
 232 static void tower_interrupt_in_callback (struct urb *urb);
 233 static void tower_interrupt_out_callback (struct urb *urb);
 234
 235 static int  tower_probe (struct usb_interface *interface, const struct usb_device_id *id);
 236 static void tower_disconnect    (struct usb_interface *interface);
 237
 238
 239 /* file operations needed when we register this driver */
 240 static const struct file_operations tower_fops = {
 241         .owner =        THIS_MODULE,
 242         .read  =        tower_read,
 243         .write =        tower_write,
 244         .open =         tower_open,
 245         .release =      tower_release,
 246         .poll =         tower_poll,
 247         .llseek =       tower_llseek,
 248 };
 249
 250 static char *legousbtower_devnode(struct device *dev, umode_t *mode)
 251 {
 252         return kasprintf(GFP_KERNEL, "usb/%s", dev_name(dev));
 253 }
 254
 255 /*
 256  * usb class driver info in order to get a minor number from the usb core,
 257  * and to have the device registered with the driver core
 258  */
 259 static struct usb_class_driver tower_class = {
 260         .name =         "legousbtower%d",
 261         .devnode =      legousbtower_devnode,
 262         .fops =         &tower_fops,
 263         .minor_base =   LEGO_USB_TOWER_MINOR_BASE,
 264 };
 265
 266
 267 /* usb specific object needed to register this driver with the usb subsystem */
 268 static struct usb_driver tower_driver = {
 269         .name =         "legousbtower",
 270         .probe =        tower_probe,
 271         .disconnect =   tower_disconnect,
 272         .id_table =     tower_table,
 273 };
 274
 275
 276 /**
 277  *      lego_usb_tower_debug_data
 278  */
 279 static inline void lego_usb_tower_debug_data(struct device *dev,
 280                                              const char *function, int size,
 281                                              const unsigned char *data)
 282 {
 283         dev_dbg(dev, "%s - length = %d, data = %*ph\n",
 284                 function, size, size, data);
 285 }
 286
 287
 288 /**
 289  *      tower_delete
 290  */
 291 static inline void tower_delete (struct lego_usb_tower *dev)
 292 {
 293         /* free data structures */
 294         usb_free_urb(dev->interrupt_in_urb);
 295         usb_free_urb(dev->interrupt_out_urb);
 296         kfree (dev->read_buffer);
 297         kfree (dev->interrupt_in_buffer);
 298         kfree (dev->interrupt_out_buffer);
 299         usb_put_dev(dev->udev);
 300         kfree (dev);
 301 }
 302
 303
 304 /**
 305  *      tower_open
 306  */
 307 static int tower_open (struct inode *inode, struct file *file)
 308 {
 309         struct lego_usb_tower *dev = NULL;
 310         int subminor;
 311         int retval = 0;
 312         struct usb_interface *interface;
 313         struct tower_reset_reply *reset_reply;
 314         int result;
 315
 316         reset_reply = kmalloc(sizeof(*reset_reply), GFP_KERNEL);
 317
 318         if (!reset_reply) {
 319                 retval = -ENOMEM;
 320                 goto exit;
 321         }
 322
 323         nonseekable_open(inode, file);
 324         subminor = iminor(inode);
 325
 326         interface = usb_find_interface (&tower_driver, subminor);
 327
 328         if (!interface) {
 329                 pr_err("error, can't find device for minor %d\n", subminor);
 330                 retval = -ENODEV;
 331                 goto exit;
 332         }
 333
 334         dev = usb_get_intfdata(interface);
 335         if (!dev) {
 336                 retval = -ENODEV;
 337                 goto exit;
 338         }
 339
 340         /* lock this device */
 341         if (mutex_lock_interruptible(&dev->lock)) {
 342                 retval = -ERESTARTSYS;
 343                 goto exit;
 344         }
 345
 346
 347         /* allow opening only once */
 348         if (dev->open_count) {
 349                 retval = -EBUSY;
 350                 goto unlock_exit;
 351         }
 352
 353         /* reset the tower */
 354         result = usb_control_msg (dev->udev,
 355                                   usb_rcvctrlpipe(dev->udev, 0),
 356                                   LEGO_USB_TOWER_REQUEST_RESET,
 357                                   USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
 358                                   0,
 359                                   0,
 360                                   reset_reply,
 361                                   sizeof(*reset_reply),
 362                                   1000);
 363         if (result < 0) {
 364                 dev_err(&dev->udev->dev,
 365                         "LEGO USB Tower reset control request failed\n");
 366                 retval = result;
 367                 goto unlock_exit;
 368         }
 369
 370         /* initialize in direction */
 371         dev->read_buffer_length = 0;
 372         dev->read_packet_length = 0;
 373         usb_fill_int_urb (dev->interrupt_in_urb,
 374                           dev->udev,
 375                           usb_rcvintpipe(dev->udev, dev->interrupt_in_endpoint->bEndpointAddress),
 376                           dev->interrupt_in_buffer,
 377                           usb_endpoint_maxp(dev->interrupt_in_endpoint),
 378                           tower_interrupt_in_callback,
 379                           dev,
 380                           dev->interrupt_in_interval);
 381
 382         dev->interrupt_in_running = 1;
 383         dev->interrupt_in_done = 0;
 384         mb();
 385
 386         retval = usb_submit_urb (dev->interrupt_in_urb, GFP_KERNEL);
 387         if (retval) {
 388                 dev_err(&dev->udev->dev,
 389                         "Couldn't submit interrupt_in_urb %d\n", retval);
 390                 dev->interrupt_in_running = 0;
 391                 goto unlock_exit;
 392         }
 393
 394         /* save device in the file's private structure */
 395         file->private_data = dev;
 396
 397         dev->open_count = 1;
 398
 399 unlock_exit:
 400         mutex_unlock(&dev->lock);
 401
 402 exit:
 403         kfree(reset_reply);
 404         return retval;
 405 }
 406
 407 /**
 408  *      tower_release
 409  */
 410 static int tower_release (struct inode *inode, struct file *file)
 411 {
 412         struct lego_usb_tower *dev;
 413         int retval = 0;
 414
 415         dev = file->private_data;
 416
 417         if (dev == NULL) {
 418                 retval = -ENODEV;
 419                 goto exit;
 420         }
 421
 422         mutex_lock(&dev->lock);
 423
 424         if (dev->open_count != 1) {
 425                 dev_dbg(&dev->udev->dev, "%s: device not opened exactly once\n",
 426                         __func__);
 427                 retval = -ENODEV;
 428                 goto unlock_exit;
 429         }
 430
 431         if (dev->disconnected) {
 432                 /* the device was unplugged before the file was released */
 433
 434                 /* unlock here as tower_delete frees dev */
 435                 mutex_unlock(&dev->lock);
 436                 tower_delete (dev);
 437                 goto exit;
 438         }
 439
 440         /* wait until write transfer is finished */
 441         if (dev->interrupt_out_busy) {
 442                 wait_event_interruptible_timeout (dev->write_wait, !dev->interrupt_out_busy, 2 * HZ);
 443         }
 444         tower_abort_transfers (dev);
 445         dev->open_count = 0;
 446
 447 unlock_exit:
 448         mutex_unlock(&dev->lock);
 449 exit:
 450         return retval;
 451 }
 452
 453
 454 /**
 455  *      tower_abort_transfers
 456  *      aborts transfers and frees associated data structures
 457  */
 458 static void tower_abort_transfers (struct lego_usb_tower *dev)
 459 {
 460         if (dev == NULL)
 461                 return;
 462
 463         /* shutdown transfer */
 464         if (dev->interrupt_in_running) {
 465                 dev->interrupt_in_running = 0;
 466                 mb();
 467                 usb_kill_urb(dev->interrupt_in_urb);
 468         }
 469         if (dev->interrupt_out_busy)
 470                 usb_kill_urb(dev->interrupt_out_urb);
 471 }
 472
 473
 474 /**
 475  *      tower_check_for_read_packet
 476  *
 477  *      To get correct semantics for signals and non-blocking I/O
 478  *      with packetizing we pretend not to see any data in the read buffer
 479  *      until it has been there unchanged for at least
 480  *      dev->packet_timeout_jiffies, or until the buffer is full.
 481  */
 482 static void tower_check_for_read_packet (struct lego_usb_tower *dev)
 483 {
 484         spin_lock_irq (&dev->read_buffer_lock);
 485         if (!packet_timeout
 486             || time_after(jiffies, dev->read_last_arrival + dev->packet_timeout_jiffies)
 487             || dev->read_buffer_length == read_buffer_size) {
 488                 dev->read_packet_length = dev->read_buffer_length;
 489         }
 490         dev->interrupt_in_done = 0;
 491         spin_unlock_irq (&dev->read_buffer_lock);
 492 }
 493
 494
 495 /**
 496  *      tower_poll
 497  */
 498 static __poll_t tower_poll (struct file *file, poll_table *wait)
 499 {
 500         struct lego_usb_tower *dev;
 501         __poll_t mask = 0;
 502
 503         dev = file->private_data;
 504
 505         if (dev->disconnected)
 506                 return EPOLLERR | EPOLLHUP;
 507
 508         poll_wait(file, &dev->read_wait, wait);
 509         poll_wait(file, &dev->write_wait, wait);
 510
 511         tower_check_for_read_packet(dev);
 512         if (dev->read_packet_length > 0) {
 513                 mask |= EPOLLIN | EPOLLRDNORM;
 514         }
 515         if (!dev->interrupt_out_busy) {
 516                 mask |= EPOLLOUT | EPOLLWRNORM;
 517         }
 518
 519         return mask;
 520 }
 521
 522
 523 /**
 524  *      tower_llseek
 525  */
 526 static loff_t tower_llseek (struct file *file, loff_t off, int whence)
 527 {
 528         return -ESPIPE;         /* unseekable */
 529 }
 530
 531
 532 /**
 533  *      tower_read
 534  */
 535 static ssize_t tower_read (struct file *file, char __user *buffer, size_t count, loff_t *ppos)
 536 {
 537         struct lego_usb_tower *dev;
 538         size_t bytes_to_read;
 539         int i;
 540         int retval = 0;
 541         unsigned long timeout = 0;
 542
 543         dev = file->private_data;
 544
 545         /* lock this object */
 546         if (mutex_lock_interruptible(&dev->lock)) {
 547                 retval = -ERESTARTSYS;
 548                 goto exit;
 549         }
 550
 551         /* verify that the device wasn't unplugged */
 552         if (dev->disconnected) {
 553                 retval = -ENODEV;
 554                 pr_err("No device or device unplugged %d\n", retval);
 555                 goto unlock_exit;
 556         }
 557
 558         /* verify that we actually have some data to read */
 559         if (count == 0) {
 560                 dev_dbg(&dev->udev->dev, "read request of 0 bytes\n");
 561                 goto unlock_exit;
 562         }
 563
 564         if (read_timeout) {
 565                 timeout = jiffies + msecs_to_jiffies(read_timeout);
 566         }
 567
 568         /* wait for data */
 569         tower_check_for_read_packet (dev);
 570         while (dev->read_packet_length == 0) {
 571                 if (file->f_flags & O_NONBLOCK) {
 572                         retval = -EAGAIN;
 573                         goto unlock_exit;
 574                 }
 575                 retval = wait_event_interruptible_timeout(dev->read_wait, dev->interrupt_in_done, dev->packet_timeout_jiffies);
 576                 if (retval < 0) {
 577                         goto unlock_exit;
 578                 }
 579
 580                 /* reset read timeout during read or write activity */
 581                 if (read_timeout
 582                     && (dev->read_buffer_length || dev->interrupt_out_busy)) {
 583                         timeout = jiffies + msecs_to_jiffies(read_timeout);
 584                 }
 585                 /* check for read timeout */
 586                 if (read_timeout && time_after (jiffies, timeout)) {
 587                         retval = -ETIMEDOUT;
 588                         goto unlock_exit;
 589                 }
 590                 tower_check_for_read_packet (dev);
 591         }
 592
 593         /* copy the data from read_buffer into userspace */
 594         bytes_to_read = min(count, dev->read_packet_length);
 595
 596         if (copy_to_user (buffer, dev->read_buffer, bytes_to_read)) {
 597                 retval = -EFAULT;
 598                 goto unlock_exit;
 599         }
 600
 601         spin_lock_irq (&dev->read_buffer_lock);
 602         dev->read_buffer_length -= bytes_to_read;
 603         dev->read_packet_length -= bytes_to_read;
 604         for (i=0; i<dev->read_buffer_length; i++) {
 605                 dev->read_buffer[i] = dev->read_buffer[i+bytes_to_read];
 606         }
 607         spin_unlock_irq (&dev->read_buffer_lock);
 608
 609         retval = bytes_to_read;
 610
 611 unlock_exit:
 612         /* unlock the device */
 613         mutex_unlock(&dev->lock);
 614
 615 exit:
 616         return retval;
 617 }
 618
 619
 620 /**
 621  *      tower_write
 622  */
 623 static ssize_t tower_write (struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
 624 {
 625         struct lego_usb_tower *dev;
 626         size_t bytes_to_write;
 627         int retval = 0;
 628
 629         dev = file->private_data;
 630
 631         /* lock this object */
 632         if (mutex_lock_interruptible(&dev->lock)) {
 633                 retval = -ERESTARTSYS;
 634                 goto exit;
 635         }
 636
 637         /* verify that the device wasn't unplugged */
 638         if (dev->disconnected) {
 639                 retval = -ENODEV;
 640                 pr_err("No device or device unplugged %d\n", retval);
 641                 goto unlock_exit;
 642         }
 643
 644         /* verify that we actually have some data to write */
 645         if (count == 0) {
 646                 dev_dbg(&dev->udev->dev, "write request of 0 bytes\n");
 647                 goto unlock_exit;
 648         }
 649
 650         /* wait until previous transfer is finished */
 651         while (dev->interrupt_out_busy) {
 652                 if (file->f_flags & O_NONBLOCK) {
 653                         retval = -EAGAIN;
 654                         goto unlock_exit;
 655                 }
 656                 retval = wait_event_interruptible (dev->write_wait, !dev->interrupt_out_busy);
 657                 if (retval) {
 658                         goto unlock_exit;
 659                 }
 660         }
 661
 662         /* write the data into interrupt_out_buffer from userspace */
 663         bytes_to_write = min_t(int, count, write_buffer_size);
 664         dev_dbg(&dev->udev->dev, "%s: count = %zd, bytes_to_write = %zd\n",
 665                 __func__, count, bytes_to_write);
 666
 667         if (copy_from_user (dev->interrupt_out_buffer, buffer, bytes_to_write)) {
 668                 retval = -EFAULT;
 669                 goto unlock_exit;
 670         }
 671
 672         /* send off the urb */
 673         usb_fill_int_urb(dev->interrupt_out_urb,
 674                          dev->udev,
 675                          usb_sndintpipe(dev->udev, dev->interrupt_out_endpoint->bEndpointAddress),
 676                          dev->interrupt_out_buffer,
 677                          bytes_to_write,
 678                          tower_interrupt_out_callback,
 679                          dev,
 680                          dev->interrupt_out_interval);
 681
 682         dev->interrupt_out_busy = 1;
 683         wmb();
 684
 685         retval = usb_submit_urb (dev->interrupt_out_urb, GFP_KERNEL);
 686         if (retval) {
 687                 dev->interrupt_out_busy = 0;
 688                 dev_err(&dev->udev->dev,
 689                         "Couldn't submit interrupt_out_urb %d\n", retval);
 690                 goto unlock_exit;
 691         }
 692         retval = bytes_to_write;
 693
 694 unlock_exit:
 695         /* unlock the device */
 696         mutex_unlock(&dev->lock);
 697
 698 exit:
 699         return retval;
 700 }
 701
 702
 703 /**
 704  *      tower_interrupt_in_callback
 705  */
 706 static void tower_interrupt_in_callback (struct urb *urb)
 707 {
 708         struct lego_usb_tower *dev = urb->context;
 709         int status = urb->status;
 710         int retval;
 711         unsigned long flags;
 712
 713         lego_usb_tower_debug_data(&dev->udev->dev, __func__,
 714                                   urb->actual_length, urb->transfer_buffer);
 715
 716         if (status) {
 717                 if (status == -ENOENT ||
 718                     status == -ECONNRESET ||
 719                     status == -ESHUTDOWN) {
 720                         goto exit;
 721                 } else {
 722                         dev_dbg(&dev->udev->dev,
 723                                 "%s: nonzero status received: %d\n", __func__,
 724                                 status);
 725                         goto resubmit; /* maybe we can recover */
 726                 }
 727         }
 728
 729         if (urb->actual_length > 0) {
 730                 spin_lock_irqsave(&dev->read_buffer_lock, flags);
 731                 if (dev->read_buffer_length + urb->actual_length < read_buffer_size) {
 732                         memcpy (dev->read_buffer + dev->read_buffer_length,
 733                                 dev->interrupt_in_buffer,
 734                                 urb->actual_length);
 735                         dev->read_buffer_length += urb->actual_length;
 736                         dev->read_last_arrival = jiffies;
 737                         dev_dbg(&dev->udev->dev, "%s: received %d bytes\n",
 738                                 __func__, urb->actual_length);
 739                 } else {
 740                         pr_warn("read_buffer overflow, %d bytes dropped\n",
 741                                 urb->actual_length);
 742                 }
 743                 spin_unlock_irqrestore(&dev->read_buffer_lock, flags);
 744         }
 745
 746 resubmit:
 747         /* resubmit if we're still running */
 748         if (dev->interrupt_in_running) {
 749                 retval = usb_submit_urb (dev->interrupt_in_urb, GFP_ATOMIC);
 750                 if (retval)
 751                         dev_err(&dev->udev->dev,
 752                                 "%s: usb_submit_urb failed (%d)\n",
 753                                 __func__, retval);
 754         }
 755
 756 exit:
 757         dev->interrupt_in_done = 1;
 758         wake_up_interruptible (&dev->read_wait);
 759 }
 760
 761
 762 /**
 763  *      tower_interrupt_out_callback
 764  */
 765 static void tower_interrupt_out_callback (struct urb *urb)
 766 {
 767         struct lego_usb_tower *dev = urb->context;
 768         int status = urb->status;
 769
 770         lego_usb_tower_debug_data(&dev->udev->dev, __func__,
 771                                   urb->actual_length, urb->transfer_buffer);
 772
 773         /* sync/async unlink faults aren't errors */
 774         if (status && !(status == -ENOENT ||
 775                         status == -ECONNRESET ||
 776                         status == -ESHUTDOWN)) {
 777                 dev_dbg(&dev->udev->dev,
 778                         "%s: nonzero write bulk status received: %d\n", __func__,
 779                         status);
 780         }
 781
 782         dev->interrupt_out_busy = 0;
 783         wake_up_interruptible(&dev->write_wait);
 784 }
 785
 786
 787 /**
 788  *      tower_probe
 789  *
 790  *      Called by the usb core when a new device is connected that it thinks
 791  *      this driver might be interested in.
 792  */
 793 static int tower_probe (struct usb_interface *interface, const struct usb_device_id *id)
 794 {
 795         struct device *idev = &interface->dev;
 796         struct usb_device *udev = interface_to_usbdev(interface);
 797         struct lego_usb_tower *dev = NULL;
 798         struct tower_get_version_reply *get_version_reply = NULL;
 799         int retval = -ENOMEM;
 800         int result;
 801
 802         /* allocate memory for our device state and initialize it */
 803
 804         dev = kmalloc (sizeof(struct lego_usb_tower), GFP_KERNEL);
 805
 806         if (!dev)
 807                 goto exit;
 808
 809         mutex_init(&dev->lock);
 810
 811         dev->udev = usb_get_dev(udev);
 812         dev->open_count = 0;
 813         dev->disconnected = 0;
 814
 815         dev->read_buffer = NULL;
 816         dev->read_buffer_length = 0;
 817         dev->read_packet_length = 0;
 818         spin_lock_init (&dev->read_buffer_lock);
 819         dev->packet_timeout_jiffies = msecs_to_jiffies(packet_timeout);
 820         dev->read_last_arrival = jiffies;
 821
 822         init_waitqueue_head (&dev->read_wait);
 823         init_waitqueue_head (&dev->write_wait);
 824
 825         dev->interrupt_in_buffer = NULL;
 826         dev->interrupt_in_endpoint = NULL;
 827         dev->interrupt_in_urb = NULL;
 828         dev->interrupt_in_running = 0;
 829         dev->interrupt_in_done = 0;
 830
 831         dev->interrupt_out_buffer = NULL;
 832         dev->interrupt_out_endpoint = NULL;
 833         dev->interrupt_out_urb = NULL;
 834         dev->interrupt_out_busy = 0;
 835
 836         result = usb_find_common_endpoints_reverse(interface->cur_altsetting,
 837                         NULL, NULL,
 838                         &dev->interrupt_in_endpoint,
 839                         &dev->interrupt_out_endpoint);
 840         if (result) {
 841                 dev_err(idev, "interrupt endpoints not found\n");
 842                 retval = result;
 843                 goto error;
 844         }
 845
 846         dev->read_buffer = kmalloc (read_buffer_size, GFP_KERNEL);
 847         if (!dev->read_buffer)
 848                 goto error;
 849         dev->interrupt_in_buffer = kmalloc (usb_endpoint_maxp(dev->interrupt_in_endpoint), GFP_KERNEL);
 850         if (!dev->interrupt_in_buffer)
 851                 goto error;
 852         dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
 853         if (!dev->interrupt_in_urb)
 854                 goto error;
 855         dev->interrupt_out_buffer = kmalloc (write_buffer_size, GFP_KERNEL);
 856         if (!dev->interrupt_out_buffer)
 857                 goto error;
 858         dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
 859         if (!dev->interrupt_out_urb)
 860                 goto error;
 861         dev->interrupt_in_interval = interrupt_in_interval ? interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
 862         dev->interrupt_out_interval = interrupt_out_interval ? interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
 863
 864         get_version_reply = kmalloc(sizeof(*get_version_reply), GFP_KERNEL);
 865
 866         if (!get_version_reply) {
 867                 retval = -ENOMEM;
 868                 goto error;
 869         }
 870
 871         /* get the firmware version and log it */
 872         result = usb_control_msg (udev,
 873                                   usb_rcvctrlpipe(udev, 0),
 874                                   LEGO_USB_TOWER_REQUEST_GET_VERSION,
 875                                   USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
 876                                   0,
 877                                   0,
 878                                   get_version_reply,
 879                                   sizeof(*get_version_reply),
 880                                   1000);
 881         if (result != sizeof(*get_version_reply)) {
 882                 if (result >= 0)
 883                         result = -EIO;
 884                 dev_err(idev, "get version request failed: %d\n", result);
 885                 retval = result;
 886                 goto error;
 887         }
 888         dev_info(&interface->dev,
 889                  "LEGO USB Tower firmware version is %d.%d build %d\n",
 890                  get_version_reply->major,
 891                  get_version_reply->minor,
 892                  le16_to_cpu(get_version_reply->build_no));
 893
 894         /* we can register the device now, as it is ready */
 895         usb_set_intfdata (interface, dev);
 896
 897         retval = usb_register_dev (interface, &tower_class);
 898
 899         if (retval) {
 900                 /* something prevented us from registering this driver */
 901                 dev_err(idev, "Not able to get a minor for this device.\n");
 902                 goto error;
 903         }
 904         dev->minor = interface->minor;
 905
 906         /* let the user know what node this device is now attached to */
 907         dev_info(&interface->dev, "LEGO USB Tower #%d now attached to major "
 908                  "%d minor %d\n", (dev->minor - LEGO_USB_TOWER_MINOR_BASE),
 909                  USB_MAJOR, dev->minor);
 910
 911 exit:
 912         kfree(get_version_reply);
 913         return retval;
 914
 915 error:
 916         kfree(get_version_reply);
 917         tower_delete(dev);
 918         return retval;
 919 }
 920
 921
 922 /**
 923  *      tower_disconnect
 924  *
 925  *      Called by the usb core when the device is removed from the system.
 926  */
 927 static void tower_disconnect (struct usb_interface *interface)
 928 {
 929         struct lego_usb_tower *dev;
 930         int minor;
 931
 932         dev = usb_get_intfdata (interface);
 933
 934         minor = dev->minor;
 935
 936         /* give back our minor and prevent further open() */
 937         usb_deregister_dev (interface, &tower_class);
 938
 939         /* stop I/O */
 940         usb_poison_urb(dev->interrupt_in_urb);
 941         usb_poison_urb(dev->interrupt_out_urb);
 942
 943         mutex_lock(&dev->lock);
 944
 945         /* if the device is not opened, then we clean up right now */
 946         if (!dev->open_count) {
 947                 mutex_unlock(&dev->lock);
 948                 tower_delete (dev);
 949         } else {
 950                 dev->disconnected = 1;
 951                 /* wake up pollers */
 952                 wake_up_interruptible_all(&dev->read_wait);
 953                 wake_up_interruptible_all(&dev->write_wait);
 954                 mutex_unlock(&dev->lock);
 955         }
 956
 957         dev_info(&interface->dev, "LEGO USB Tower #%d now disconnected\n",
 958                  (minor - LEGO_USB_TOWER_MINOR_BASE));
 959 }
 960
 961 module_usb_driver(tower_driver);
 962
 963 MODULE_AUTHOR(DRIVER_AUTHOR);
 964 MODULE_DESCRIPTION(DRIVER_DESC);
 965 #ifdef MODULE_LICENSE
 966 MODULE_LICENSE("GPL");
 967 #endif