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         if (mutex_lock_interruptible(&dev->lock)) {
 423                 retval = -ERESTARTSYS;
 424                 goto exit;
 425         }
 426
 427         if (dev->open_count != 1) {
 428                 dev_dbg(&dev->udev->dev, "%s: device not opened exactly once\n",
 429                         __func__);
 430                 retval = -ENODEV;
 431                 goto unlock_exit;
 432         }
 433
 434         if (dev->disconnected) {
 435                 /* the device was unplugged before the file was released */
 436
 437                 /* unlock here as tower_delete frees dev */
 438                 mutex_unlock(&dev->lock);
 439                 tower_delete (dev);
 440                 goto exit;
 441         }
 442
 443         /* wait until write transfer is finished */
 444         if (dev->interrupt_out_busy) {
 445                 wait_event_interruptible_timeout (dev->write_wait, !dev->interrupt_out_busy, 2 * HZ);
 446         }
 447         tower_abort_transfers (dev);
 448         dev->open_count = 0;
 449
 450 unlock_exit:
 451         mutex_unlock(&dev->lock);
 452 exit:
 453         return retval;
 454 }
 455
 456
 457 /**
 458  *      tower_abort_transfers
 459  *      aborts transfers and frees associated data structures
 460  */
 461 static void tower_abort_transfers (struct lego_usb_tower *dev)
 462 {
 463         if (dev == NULL)
 464                 return;
 465
 466         /* shutdown transfer */
 467         if (dev->interrupt_in_running) {
 468                 dev->interrupt_in_running = 0;
 469                 mb();
 470                 usb_kill_urb(dev->interrupt_in_urb);
 471         }
 472         if (dev->interrupt_out_busy)
 473                 usb_kill_urb(dev->interrupt_out_urb);
 474 }
 475
 476
 477 /**
 478  *      tower_check_for_read_packet
 479  *
 480  *      To get correct semantics for signals and non-blocking I/O
 481  *      with packetizing we pretend not to see any data in the read buffer
 482  *      until it has been there unchanged for at least
 483  *      dev->packet_timeout_jiffies, or until the buffer is full.
 484  */
 485 static void tower_check_for_read_packet (struct lego_usb_tower *dev)
 486 {
 487         spin_lock_irq (&dev->read_buffer_lock);
 488         if (!packet_timeout
 489             || time_after(jiffies, dev->read_last_arrival + dev->packet_timeout_jiffies)
 490             || dev->read_buffer_length == read_buffer_size) {
 491                 dev->read_packet_length = dev->read_buffer_length;
 492         }
 493         dev->interrupt_in_done = 0;
 494         spin_unlock_irq (&dev->read_buffer_lock);
 495 }
 496
 497
 498 /**
 499  *      tower_poll
 500  */
 501 static __poll_t tower_poll (struct file *file, poll_table *wait)
 502 {
 503         struct lego_usb_tower *dev;
 504         __poll_t mask = 0;
 505
 506         dev = file->private_data;
 507
 508         if (dev->disconnected)
 509                 return EPOLLERR | EPOLLHUP;
 510
 511         poll_wait(file, &dev->read_wait, wait);
 512         poll_wait(file, &dev->write_wait, wait);
 513
 514         tower_check_for_read_packet(dev);
 515         if (dev->read_packet_length > 0) {
 516                 mask |= EPOLLIN | EPOLLRDNORM;
 517         }
 518         if (!dev->interrupt_out_busy) {
 519                 mask |= EPOLLOUT | EPOLLWRNORM;
 520         }
 521
 522         return mask;
 523 }
 524
 525
 526 /**
 527  *      tower_llseek
 528  */
 529 static loff_t tower_llseek (struct file *file, loff_t off, int whence)
 530 {
 531         return -ESPIPE;         /* unseekable */
 532 }
 533
 534
 535 /**
 536  *      tower_read
 537  */
 538 static ssize_t tower_read (struct file *file, char __user *buffer, size_t count, loff_t *ppos)
 539 {
 540         struct lego_usb_tower *dev;
 541         size_t bytes_to_read;
 542         int i;
 543         int retval = 0;
 544         unsigned long timeout = 0;
 545
 546         dev = file->private_data;
 547
 548         /* lock this object */
 549         if (mutex_lock_interruptible(&dev->lock)) {
 550                 retval = -ERESTARTSYS;
 551                 goto exit;
 552         }
 553
 554         /* verify that the device wasn't unplugged */
 555         if (dev->disconnected) {
 556                 retval = -ENODEV;
 557                 pr_err("No device or device unplugged %d\n", retval);
 558                 goto unlock_exit;
 559         }
 560
 561         /* verify that we actually have some data to read */
 562         if (count == 0) {
 563                 dev_dbg(&dev->udev->dev, "read request of 0 bytes\n");
 564                 goto unlock_exit;
 565         }
 566
 567         if (read_timeout) {
 568                 timeout = jiffies + msecs_to_jiffies(read_timeout);
 569         }
 570
 571         /* wait for data */
 572         tower_check_for_read_packet (dev);
 573         while (dev->read_packet_length == 0) {
 574                 if (file->f_flags & O_NONBLOCK) {
 575                         retval = -EAGAIN;
 576                         goto unlock_exit;
 577                 }
 578                 retval = wait_event_interruptible_timeout(dev->read_wait, dev->interrupt_in_done, dev->packet_timeout_jiffies);
 579                 if (retval < 0) {
 580                         goto unlock_exit;
 581                 }
 582
 583                 /* reset read timeout during read or write activity */
 584                 if (read_timeout
 585                     && (dev->read_buffer_length || dev->interrupt_out_busy)) {
 586                         timeout = jiffies + msecs_to_jiffies(read_timeout);
 587                 }
 588                 /* check for read timeout */
 589                 if (read_timeout && time_after (jiffies, timeout)) {
 590                         retval = -ETIMEDOUT;
 591                         goto unlock_exit;
 592                 }
 593                 tower_check_for_read_packet (dev);
 594         }
 595
 596         /* copy the data from read_buffer into userspace */
 597         bytes_to_read = min(count, dev->read_packet_length);
 598
 599         if (copy_to_user (buffer, dev->read_buffer, bytes_to_read)) {
 600                 retval = -EFAULT;
 601                 goto unlock_exit;
 602         }
 603
 604         spin_lock_irq (&dev->read_buffer_lock);
 605         dev->read_buffer_length -= bytes_to_read;
 606         dev->read_packet_length -= bytes_to_read;
 607         for (i=0; i<dev->read_buffer_length; i++) {
 608                 dev->read_buffer[i] = dev->read_buffer[i+bytes_to_read];
 609         }
 610         spin_unlock_irq (&dev->read_buffer_lock);
 611
 612         retval = bytes_to_read;
 613
 614 unlock_exit:
 615         /* unlock the device */
 616         mutex_unlock(&dev->lock);
 617
 618 exit:
 619         return retval;
 620 }
 621
 622
 623 /**
 624  *      tower_write
 625  */
 626 static ssize_t tower_write (struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
 627 {
 628         struct lego_usb_tower *dev;
 629         size_t bytes_to_write;
 630         int retval = 0;
 631
 632         dev = file->private_data;
 633
 634         /* lock this object */
 635         if (mutex_lock_interruptible(&dev->lock)) {
 636                 retval = -ERESTARTSYS;
 637                 goto exit;
 638         }
 639
 640         /* verify that the device wasn't unplugged */
 641         if (dev->disconnected) {
 642                 retval = -ENODEV;
 643                 pr_err("No device or device unplugged %d\n", retval);
 644                 goto unlock_exit;
 645         }
 646
 647         /* verify that we actually have some data to write */
 648         if (count == 0) {
 649                 dev_dbg(&dev->udev->dev, "write request of 0 bytes\n");
 650                 goto unlock_exit;
 651         }
 652
 653         /* wait until previous transfer is finished */
 654         while (dev->interrupt_out_busy) {
 655                 if (file->f_flags & O_NONBLOCK) {
 656                         retval = -EAGAIN;
 657                         goto unlock_exit;
 658                 }
 659                 retval = wait_event_interruptible (dev->write_wait, !dev->interrupt_out_busy);
 660                 if (retval) {
 661                         goto unlock_exit;
 662                 }
 663         }
 664
 665         /* write the data into interrupt_out_buffer from userspace */
 666         bytes_to_write = min_t(int, count, write_buffer_size);
 667         dev_dbg(&dev->udev->dev, "%s: count = %zd, bytes_to_write = %zd\n",
 668                 __func__, count, bytes_to_write);
 669
 670         if (copy_from_user (dev->interrupt_out_buffer, buffer, bytes_to_write)) {
 671                 retval = -EFAULT;
 672                 goto unlock_exit;
 673         }
 674
 675         /* send off the urb */
 676         usb_fill_int_urb(dev->interrupt_out_urb,
 677                          dev->udev,
 678                          usb_sndintpipe(dev->udev, dev->interrupt_out_endpoint->bEndpointAddress),
 679                          dev->interrupt_out_buffer,
 680                          bytes_to_write,
 681                          tower_interrupt_out_callback,
 682                          dev,
 683                          dev->interrupt_out_interval);
 684
 685         dev->interrupt_out_busy = 1;
 686         wmb();
 687
 688         retval = usb_submit_urb (dev->interrupt_out_urb, GFP_KERNEL);
 689         if (retval) {
 690                 dev->interrupt_out_busy = 0;
 691                 dev_err(&dev->udev->dev,
 692                         "Couldn't submit interrupt_out_urb %d\n", retval);
 693                 goto unlock_exit;
 694         }
 695         retval = bytes_to_write;
 696
 697 unlock_exit:
 698         /* unlock the device */
 699         mutex_unlock(&dev->lock);
 700
 701 exit:
 702         return retval;
 703 }
 704
 705
 706 /**
 707  *      tower_interrupt_in_callback
 708  */
 709 static void tower_interrupt_in_callback (struct urb *urb)
 710 {
 711         struct lego_usb_tower *dev = urb->context;
 712         int status = urb->status;
 713         int retval;
 714         unsigned long flags;
 715
 716         lego_usb_tower_debug_data(&dev->udev->dev, __func__,
 717                                   urb->actual_length, urb->transfer_buffer);
 718
 719         if (status) {
 720                 if (status == -ENOENT ||
 721                     status == -ECONNRESET ||
 722                     status == -ESHUTDOWN) {
 723                         goto exit;
 724                 } else {
 725                         dev_dbg(&dev->udev->dev,
 726                                 "%s: nonzero status received: %d\n", __func__,
 727                                 status);
 728                         goto resubmit; /* maybe we can recover */
 729                 }
 730         }
 731
 732         if (urb->actual_length > 0) {
 733                 spin_lock_irqsave(&dev->read_buffer_lock, flags);
 734                 if (dev->read_buffer_length + urb->actual_length < read_buffer_size) {
 735                         memcpy (dev->read_buffer + dev->read_buffer_length,
 736                                 dev->interrupt_in_buffer,
 737                                 urb->actual_length);
 738                         dev->read_buffer_length += urb->actual_length;
 739                         dev->read_last_arrival = jiffies;
 740                         dev_dbg(&dev->udev->dev, "%s: received %d bytes\n",
 741                                 __func__, urb->actual_length);
 742                 } else {
 743                         pr_warn("read_buffer overflow, %d bytes dropped\n",
 744                                 urb->actual_length);
 745                 }
 746                 spin_unlock_irqrestore(&dev->read_buffer_lock, flags);
 747         }
 748
 749 resubmit:
 750         /* resubmit if we're still running */
 751         if (dev->interrupt_in_running) {
 752                 retval = usb_submit_urb (dev->interrupt_in_urb, GFP_ATOMIC);
 753                 if (retval)
 754                         dev_err(&dev->udev->dev,
 755                                 "%s: usb_submit_urb failed (%d)\n",
 756                                 __func__, retval);
 757         }
 758
 759 exit:
 760         dev->interrupt_in_done = 1;
 761         wake_up_interruptible (&dev->read_wait);
 762 }
 763
 764
 765 /**
 766  *      tower_interrupt_out_callback
 767  */
 768 static void tower_interrupt_out_callback (struct urb *urb)
 769 {
 770         struct lego_usb_tower *dev = urb->context;
 771         int status = urb->status;
 772
 773         lego_usb_tower_debug_data(&dev->udev->dev, __func__,
 774                                   urb->actual_length, urb->transfer_buffer);
 775
 776         /* sync/async unlink faults aren't errors */
 777         if (status && !(status == -ENOENT ||
 778                         status == -ECONNRESET ||
 779                         status == -ESHUTDOWN)) {
 780                 dev_dbg(&dev->udev->dev,
 781                         "%s: nonzero write bulk status received: %d\n", __func__,
 782                         status);
 783         }
 784
 785         dev->interrupt_out_busy = 0;
 786         wake_up_interruptible(&dev->write_wait);
 787 }
 788
 789
 790 /**
 791  *      tower_probe
 792  *
 793  *      Called by the usb core when a new device is connected that it thinks
 794  *      this driver might be interested in.
 795  */
 796 static int tower_probe (struct usb_interface *interface, const struct usb_device_id *id)
 797 {
 798         struct device *idev = &interface->dev;
 799         struct usb_device *udev = interface_to_usbdev(interface);
 800         struct lego_usb_tower *dev = NULL;
 801         struct tower_get_version_reply *get_version_reply = NULL;
 802         int retval = -ENOMEM;
 803         int result;
 804
 805         /* allocate memory for our device state and initialize it */
 806
 807         dev = kmalloc (sizeof(struct lego_usb_tower), GFP_KERNEL);
 808
 809         if (!dev)
 810                 goto exit;
 811
 812         mutex_init(&dev->lock);
 813
 814         dev->udev = usb_get_dev(udev);
 815         dev->open_count = 0;
 816         dev->disconnected = 0;
 817
 818         dev->read_buffer = NULL;
 819         dev->read_buffer_length = 0;
 820         dev->read_packet_length = 0;
 821         spin_lock_init (&dev->read_buffer_lock);
 822         dev->packet_timeout_jiffies = msecs_to_jiffies(packet_timeout);
 823         dev->read_last_arrival = jiffies;
 824
 825         init_waitqueue_head (&dev->read_wait);
 826         init_waitqueue_head (&dev->write_wait);
 827
 828         dev->interrupt_in_buffer = NULL;
 829         dev->interrupt_in_endpoint = NULL;
 830         dev->interrupt_in_urb = NULL;
 831         dev->interrupt_in_running = 0;
 832         dev->interrupt_in_done = 0;
 833
 834         dev->interrupt_out_buffer = NULL;
 835         dev->interrupt_out_endpoint = NULL;
 836         dev->interrupt_out_urb = NULL;
 837         dev->interrupt_out_busy = 0;
 838
 839         result = usb_find_common_endpoints_reverse(interface->cur_altsetting,
 840                         NULL, NULL,
 841                         &dev->interrupt_in_endpoint,
 842                         &dev->interrupt_out_endpoint);
 843         if (result) {
 844                 dev_err(idev, "interrupt endpoints not found\n");
 845                 retval = result;
 846                 goto error;
 847         }
 848
 849         dev->read_buffer = kmalloc (read_buffer_size, GFP_KERNEL);
 850         if (!dev->read_buffer)
 851                 goto error;
 852         dev->interrupt_in_buffer = kmalloc (usb_endpoint_maxp(dev->interrupt_in_endpoint), GFP_KERNEL);
 853         if (!dev->interrupt_in_buffer)
 854                 goto error;
 855         dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
 856         if (!dev->interrupt_in_urb)
 857                 goto error;
 858         dev->interrupt_out_buffer = kmalloc (write_buffer_size, GFP_KERNEL);
 859         if (!dev->interrupt_out_buffer)
 860                 goto error;
 861         dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
 862         if (!dev->interrupt_out_urb)
 863                 goto error;
 864         dev->interrupt_in_interval = interrupt_in_interval ? interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
 865         dev->interrupt_out_interval = interrupt_out_interval ? interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;
 866
 867         get_version_reply = kmalloc(sizeof(*get_version_reply), GFP_KERNEL);
 868
 869         if (!get_version_reply) {
 870                 retval = -ENOMEM;
 871                 goto error;
 872         }
 873
 874         /* get the firmware version and log it */
 875         result = usb_control_msg (udev,
 876                                   usb_rcvctrlpipe(udev, 0),
 877                                   LEGO_USB_TOWER_REQUEST_GET_VERSION,
 878                                   USB_TYPE_VENDOR | USB_DIR_IN | USB_RECIP_DEVICE,
 879                                   0,
 880                                   0,
 881                                   get_version_reply,
 882                                   sizeof(*get_version_reply),
 883                                   1000);
 884         if (result < sizeof(*get_version_reply)) {
 885                 if (result >= 0)
 886                         result = -EIO;
 887                 dev_err(idev, "get version request failed: %d\n", result);
 888                 retval = result;
 889                 goto error;
 890         }
 891         dev_info(&interface->dev,
 892                  "LEGO USB Tower firmware version is %d.%d build %d\n",
 893                  get_version_reply->major,
 894                  get_version_reply->minor,
 895                  le16_to_cpu(get_version_reply->build_no));
 896
 897         /* we can register the device now, as it is ready */
 898         usb_set_intfdata (interface, dev);
 899
 900         retval = usb_register_dev (interface, &tower_class);
 901
 902         if (retval) {
 903                 /* something prevented us from registering this driver */
 904                 dev_err(idev, "Not able to get a minor for this device.\n");
 905                 goto error;
 906         }
 907         dev->minor = interface->minor;
 908
 909         /* let the user know what node this device is now attached to */
 910         dev_info(&interface->dev, "LEGO USB Tower #%d now attached to major "
 911                  "%d minor %d\n", (dev->minor - LEGO_USB_TOWER_MINOR_BASE),
 912                  USB_MAJOR, dev->minor);
 913
 914 exit:
 915         kfree(get_version_reply);
 916         return retval;
 917
 918 error:
 919         kfree(get_version_reply);
 920         tower_delete(dev);
 921         return retval;
 922 }
 923
 924
 925 /**
 926  *      tower_disconnect
 927  *
 928  *      Called by the usb core when the device is removed from the system.
 929  */
 930 static void tower_disconnect (struct usb_interface *interface)
 931 {
 932         struct lego_usb_tower *dev;
 933         int minor;
 934
 935         dev = usb_get_intfdata (interface);
 936
 937         minor = dev->minor;
 938
 939         /* give back our minor and prevent further open() */
 940         usb_deregister_dev (interface, &tower_class);
 941
 942         /* stop I/O */
 943         usb_poison_urb(dev->interrupt_in_urb);
 944         usb_poison_urb(dev->interrupt_out_urb);
 945
 946         mutex_lock(&dev->lock);
 947
 948         /* if the device is not opened, then we clean up right now */
 949         if (!dev->open_count) {
 950                 mutex_unlock(&dev->lock);
 951                 tower_delete (dev);
 952         } else {
 953                 dev->disconnected = 1;
 954                 /* wake up pollers */
 955                 wake_up_interruptible_all(&dev->read_wait);
 956                 wake_up_interruptible_all(&dev->write_wait);
 957                 mutex_unlock(&dev->lock);
 958         }
 959
 960         dev_info(&interface->dev, "LEGO USB Tower #%d now disconnected\n",
 961                  (minor - LEGO_USB_TOWER_MINOR_BASE));
 962 }
 963
 964 module_usb_driver(tower_driver);
 965
 966 MODULE_AUTHOR(DRIVER_AUTHOR);
 967 MODULE_DESCRIPTION(DRIVER_DESC);
 968 #ifdef MODULE_LICENSE
 969 MODULE_LICENSE("GPL");
 970 #endif