drivers/usb/usb-skeleton.c

   1 /*
   2  * USB Skeleton driver - 2.2
   3  *
   4  * Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com)
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License as
   8  *      published by the Free Software Foundation, version 2.
   9  *
  10  * This driver is based on the 2.6.3 version of drivers/usb/usb-skeleton.c
  11  * but has been rewritten to be easier to read and use.
  12  *
  13  */
  14
  15 #include <linux/kernel.h>
  16 #include <linux/errno.h>
  17 #include <linux/init.h>
  18 #include <linux/slab.h>
  19 #include <linux/module.h>
  20 #include <linux/kref.h>
  21 #include <asm/uaccess.h>
  22 #include <linux/usb.h>
  23 #include <linux/mutex.h>
  24
  25
  26 /* Define these values to match your devices */
  27 #define USB_SKEL_VENDOR_ID      0xfff0
  28 #define USB_SKEL_PRODUCT_ID     0xfff0
  29
  30 /* table of devices that work with this driver */
  31 static struct usb_device_id skel_table [] = {
  32         { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
  33         { }                                     /* Terminating entry */
  34 };
  35 MODULE_DEVICE_TABLE(usb, skel_table);
  36
  37
  38 /* Get a minor range for your devices from the usb maintainer */
  39 #define USB_SKEL_MINOR_BASE     192
  40
  41 /* our private defines. if this grows any larger, use your own .h file */
  42 #define MAX_TRANSFER            (PAGE_SIZE - 512)
  43 /* MAX_TRANSFER is chosen so that the VM is not stressed by
  44    allocations > PAGE_SIZE and the number of packets in a page
  45    is an integer 512 is the largest possible packet on EHCI */
  46 #define WRITES_IN_FLIGHT        8
  47 /* arbitrarily chosen */
  48
  49 /* Structure to hold all of our device specific stuff */
  50 struct usb_skel {
  51         struct usb_device       *udev;                  /* the usb device for this device */
  52         struct usb_interface    *interface;             /* the interface for this device */
  53         struct semaphore        limit_sem;              /* limiting the number of writes in progress */
  54         struct usb_anchor       submitted;              /* in case we need to retract our submissions */
  55         unsigned char           *bulk_in_buffer;        /* the buffer to receive data */
  56         size_t                  bulk_in_size;           /* the size of the receive buffer */
  57         __u8                    bulk_in_endpointAddr;   /* the address of the bulk in endpoint */
  58         __u8                    bulk_out_endpointAddr;  /* the address of the bulk out endpoint */
  59         int                     errors;                 /* the last request tanked */
  60         int                     open_count;             /* count the number of openers */
  61         spinlock_t              err_lock;               /* lock for errors */
  62         struct kref             kref;
  63         struct mutex            io_mutex;               /* synchronize I/O with disconnect */
  64 };
  65 #define to_skel_dev(d) container_of(d, struct usb_skel, kref)
  66
  67 static struct usb_driver skel_driver;
  68 static void skel_draw_down(struct usb_skel *dev);
  69
  70 static void skel_delete(struct kref *kref)
  71 {
  72         struct usb_skel *dev = to_skel_dev(kref);
  73
  74         usb_put_dev(dev->udev);
  75         kfree(dev->bulk_in_buffer);
  76         kfree(dev);
  77 }
  78
  79 static int skel_open(struct inode *inode, struct file *file)
  80 {
  81         struct usb_skel *dev;
  82         struct usb_interface *interface;
  83         int subminor;
  84         int retval = 0;
  85
  86         subminor = iminor(inode);
  87
  88         interface = usb_find_interface(&skel_driver, subminor);
  89         if (!interface) {
  90                 err ("%s - error, can't find device for minor %d",
  91                      __FUNCTION__, subminor);
  92                 retval = -ENODEV;
  93                 goto exit;
  94         }
  95
  96         dev = usb_get_intfdata(interface);
  97         if (!dev) {
  98                 retval = -ENODEV;
  99                 goto exit;
 100         }
 101
 102         /* increment our usage count for the device */
 103         kref_get(&dev->kref);
 104
 105         /* lock the device to allow correctly handling errors
 106          * in resumption */
 107         mutex_lock(&dev->io_mutex);
 108
 109         if (!dev->open_count++) {
 110                 retval = usb_autopm_get_interface(interface);
 111                         if (retval) {
 112                                 dev->open_count--;
 113                                 mutex_unlock(&dev->io_mutex);
 114                                 kref_put(&dev->kref, skel_delete);
 115                                 goto exit;
 116                         }
 117         } /* else { //uncomment this block if you want exclusive open
 118                 retval = -EBUSY;
 119                 dev->open_count--;
 120                 mutex_unlock(&dev->io_mutex);
 121                 kref_put(&dev->kref, skel_delete);
 122                 goto exit;
 123         } */
 124         /* prevent the device from being autosuspended */
 125
 126         /* save our object in the file's private structure */
 127         file->private_data = dev;
 128
 129 exit:
 130         return retval;
 131 }
 132
 133 static int skel_release(struct inode *inode, struct file *file)
 134 {
 135         struct usb_skel *dev;
 136
 137         dev = (struct usb_skel *)file->private_data;
 138         if (dev == NULL)
 139                 return -ENODEV;
 140
 141         /* allow the device to be autosuspended */
 142         mutex_lock(&dev->io_mutex);
 143         if (!--dev->open_count && dev->interface)
 144                 usb_autopm_put_interface(dev->interface);
 145         mutex_unlock(&dev->io_mutex);
 146
 147         /* decrement the count on our device */
 148         kref_put(&dev->kref, skel_delete);
 149         return 0;
 150 }
 151
 152 static int skel_flush(struct file *file, fl_owner_t id)
 153 {
 154         struct usb_skel *dev;
 155         int res;
 156
 157         dev = (struct usb_skel *)file->private_data;
 158         if (dev == NULL)
 159                 return -ENODEV;
 160
 161         /* wait for io to stop */
 162         mutex_lock(&dev->io_mutex);
 163         skel_draw_down(dev);
 164
 165         /* read out errors, leave subsequent opens a clean slate */
 166         spin_lock_irq(&dev->err_lock);
 167         res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
 168         dev->errors = 0;
 169         spin_unlock_irq(&dev->err_lock);
 170
 171         mutex_unlock(&dev->io_mutex);
 172
 173         return res;
 174 }
 175
 176 static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos)
 177 {
 178         struct usb_skel *dev;
 179         int retval;
 180         int bytes_read;
 181
 182         dev = (struct usb_skel *)file->private_data;
 183
 184         mutex_lock(&dev->io_mutex);
 185         if (!dev->interface) {          /* disconnect() was called */
 186                 retval = -ENODEV;
 187                 goto exit;
 188         }
 189
 190         /* do a blocking bulk read to get data from the device */
 191         retval = usb_bulk_msg(dev->udev,
 192                               usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
 193                               dev->bulk_in_buffer,
 194                               min(dev->bulk_in_size, count),
 195                               &bytes_read, 10000);
 196
 197         /* if the read was successful, copy the data to userspace */
 198         if (!retval) {
 199                 if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
 200                         retval = -EFAULT;
 201                 else
 202                         retval = bytes_read;
 203         }
 204
 205 exit:
 206         mutex_unlock(&dev->io_mutex);
 207         return retval;
 208 }
 209
 210 static void skel_write_bulk_callback(struct urb *urb)
 211 {
 212         struct usb_skel *dev;
 213
 214         dev = (struct usb_skel *)urb->context;
 215
 216         /* sync/async unlink faults aren't errors */
 217         if (urb->status) {
 218                 if(!(urb->status == -ENOENT ||
 219                     urb->status == -ECONNRESET ||
 220                     urb->status == -ESHUTDOWN))
 221                         err("%s - nonzero write bulk status received: %d",
 222                             __FUNCTION__, urb->status);
 223
 224                 spin_lock(&dev->err_lock);
 225                 dev->errors = urb->status;
 226                 spin_unlock(&dev->err_lock);
 227         }
 228
 229         /* free up our allocated buffer */
 230         usb_buffer_free(urb->dev, urb->transfer_buffer_length,
 231                         urb->transfer_buffer, urb->transfer_dma);
 232         up(&dev->limit_sem);
 233 }
 234
 235 static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos)
 236 {
 237         struct usb_skel *dev;
 238         int retval = 0;
 239         struct urb *urb = NULL;
 240         char *buf = NULL;
 241         size_t writesize = min(count, (size_t)MAX_TRANSFER);
 242
 243         dev = (struct usb_skel *)file->private_data;
 244
 245         /* verify that we actually have some data to write */
 246         if (count == 0)
 247                 goto exit;
 248
 249         /* limit the number of URBs in flight to stop a user from using up all RAM */
 250         if (down_interruptible(&dev->limit_sem)) {
 251                 retval = -ERESTARTSYS;
 252                 goto exit;
 253         }
 254
 255         spin_lock_irq(&dev->err_lock);
 256         if ((retval = dev->errors) < 0) {
 257                 /* any error is reported once */
 258                 dev->errors = 0;
 259                 /* to preserve notifications about reset */
 260                 retval = (retval == -EPIPE) ? retval : -EIO;
 261         }
 262         spin_unlock_irq(&dev->err_lock);
 263         if (retval < 0)
 264                 goto error;
 265
 266         /* create a urb, and a buffer for it, and copy the data to the urb */
 267         urb = usb_alloc_urb(0, GFP_KERNEL);
 268         if (!urb) {
 269                 retval = -ENOMEM;
 270                 goto error;
 271         }
 272
 273         buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma);
 274         if (!buf) {
 275                 retval = -ENOMEM;
 276                 goto error;
 277         }
 278
 279         if (copy_from_user(buf, user_buffer, writesize)) {
 280                 retval = -EFAULT;
 281                 goto error;
 282         }
 283
 284         /* this lock makes sure we don't submit URBs to gone devices */
 285         mutex_lock(&dev->io_mutex);
 286         if (!dev->interface) {          /* disconnect() was called */
 287                 mutex_unlock(&dev->io_mutex);
 288                 retval = -ENODEV;
 289                 goto error;
 290         }
 291
 292         /* initialize the urb properly */
 293         usb_fill_bulk_urb(urb, dev->udev,
 294                           usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
 295                           buf, writesize, skel_write_bulk_callback, dev);
 296         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 297         usb_anchor_urb(urb, &dev->submitted);
 298
 299         /* send the data out the bulk port */
 300         retval = usb_submit_urb(urb, GFP_KERNEL);
 301         mutex_unlock(&dev->io_mutex);
 302         if (retval) {
 303                 err("%s - failed submitting write urb, error %d", __FUNCTION__, retval);
 304                 goto error_unanchor;
 305         }
 306
 307         /* release our reference to this urb, the USB core will eventually free it entirely */
 308         usb_free_urb(urb);
 309
 310
 311         return writesize;
 312
 313 error_unanchor:
 314         usb_unanchor_urb(urb);
 315 error:
 316         if (urb) {
 317                 usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
 318                 usb_free_urb(urb);
 319         }
 320         up(&dev->limit_sem);
 321
 322 exit:
 323         return retval;
 324 }
 325
 326 static const struct file_operations skel_fops = {
 327         .owner =        THIS_MODULE,
 328         .read =         skel_read,
 329         .write =        skel_write,
 330         .open =         skel_open,
 331         .release =      skel_release,
 332         .flush =        skel_flush,
 333 };
 334
 335 /*
 336  * usb class driver info in order to get a minor number from the usb core,
 337  * and to have the device registered with the driver core
 338  */
 339 static struct usb_class_driver skel_class = {
 340         .name =         "skel%d",
 341         .fops =         &skel_fops,
 342         .minor_base =   USB_SKEL_MINOR_BASE,
 343 };
 344
 345 static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id)
 346 {
 347         struct usb_skel *dev;
 348         struct usb_host_interface *iface_desc;
 349         struct usb_endpoint_descriptor *endpoint;
 350         size_t buffer_size;
 351         int i;
 352         int retval = -ENOMEM;
 353
 354         /* allocate memory for our device state and initialize it */
 355         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 356         if (!dev) {
 357                 err("Out of memory");
 358                 goto error;
 359         }
 360         kref_init(&dev->kref);
 361         sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
 362         mutex_init(&dev->io_mutex);
 363         spin_lock_init(&dev->err_lock);
 364         init_usb_anchor(&dev->submitted);
 365
 366         dev->udev = usb_get_dev(interface_to_usbdev(interface));
 367         dev->interface = interface;
 368
 369         /* set up the endpoint information */
 370         /* use only the first bulk-in and bulk-out endpoints */
 371         iface_desc = interface->cur_altsetting;
 372         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 373                 endpoint = &iface_desc->endpoint[i].desc;
 374
 375                 if (!dev->bulk_in_endpointAddr &&
 376                     usb_endpoint_is_bulk_in(endpoint)) {
 377                         /* we found a bulk in endpoint */
 378                         buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
 379                         dev->bulk_in_size = buffer_size;
 380                         dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
 381                         dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
 382                         if (!dev->bulk_in_buffer) {
 383                                 err("Could not allocate bulk_in_buffer");
 384                                 goto error;
 385                         }
 386                 }
 387
 388                 if (!dev->bulk_out_endpointAddr &&
 389                     usb_endpoint_is_bulk_out(endpoint)) {
 390                         /* we found a bulk out endpoint */
 391                         dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
 392                 }
 393         }
 394         if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
 395                 err("Could not find both bulk-in and bulk-out endpoints");
 396                 goto error;
 397         }
 398
 399         /* save our data pointer in this interface device */
 400         usb_set_intfdata(interface, dev);
 401
 402         /* we can register the device now, as it is ready */
 403         retval = usb_register_dev(interface, &skel_class);
 404         if (retval) {
 405                 /* something prevented us from registering this driver */
 406                 err("Not able to get a minor for this device.");
 407                 usb_set_intfdata(interface, NULL);
 408                 goto error;
 409         }
 410
 411         /* let the user know what node this device is now attached to */
 412         info("USB Skeleton device now attached to USBSkel-%d", interface->minor);
 413         return 0;
 414
 415 error:
 416         if (dev)
 417                 /* this frees allocated memory */
 418                 kref_put(&dev->kref, skel_delete);
 419         return retval;
 420 }
 421
 422 static void skel_disconnect(struct usb_interface *interface)
 423 {
 424         struct usb_skel *dev;
 425         int minor = interface->minor;
 426
 427         dev = usb_get_intfdata(interface);
 428         usb_set_intfdata(interface, NULL);
 429
 430         /* give back our minor */
 431         usb_deregister_dev(interface, &skel_class);
 432
 433         /* prevent more I/O from starting */
 434         mutex_lock(&dev->io_mutex);
 435         dev->interface = NULL;
 436         mutex_unlock(&dev->io_mutex);
 437
 438         usb_kill_anchored_urbs(&dev->submitted);
 439
 440         /* decrement our usage count */
 441         kref_put(&dev->kref, skel_delete);
 442
 443         info("USB Skeleton #%d now disconnected", minor);
 444 }
 445
 446 static void skel_draw_down(struct usb_skel *dev)
 447 {
 448         int time;
 449
 450         time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
 451         if (!time)
 452                 usb_kill_anchored_urbs(&dev->submitted);
 453 }
 454
 455 static int skel_suspend(struct usb_interface *intf, pm_message_t message)
 456 {
 457         struct usb_skel *dev = usb_get_intfdata(intf);
 458
 459         if (!dev)
 460                 return 0;
 461         skel_draw_down(dev);
 462         return 0;
 463 }
 464
 465 static int skel_resume (struct usb_interface *intf)
 466 {
 467         return 0;
 468 }
 469
 470 static int skel_pre_reset(struct usb_interface *intf)
 471 {
 472         struct usb_skel *dev = usb_get_intfdata(intf);
 473
 474         mutex_lock(&dev->io_mutex);
 475         skel_draw_down(dev);
 476
 477         return 0;
 478 }
 479
 480 static int skel_post_reset(struct usb_interface *intf)
 481 {
 482         struct usb_skel *dev = usb_get_intfdata(intf);
 483
 484         /* we are sure no URBs are active - no locking needed */
 485         dev->errors = -EPIPE;
 486         mutex_unlock(&dev->io_mutex);
 487
 488         return 0;
 489 }
 490
 491 static struct usb_driver skel_driver = {
 492         .name =         "skeleton",
 493         .probe =        skel_probe,
 494         .disconnect =   skel_disconnect,
 495         .suspend =      skel_suspend,
 496         .resume =       skel_resume,
 497         .pre_reset =    skel_pre_reset,
 498         .post_reset =   skel_post_reset,
 499         .id_table =     skel_table,
 500         .supports_autosuspend = 1,
 501 };
 502
 503 static int __init usb_skel_init(void)
 504 {
 505         int result;
 506
 507         /* register this driver with the USB subsystem */
 508         result = usb_register(&skel_driver);
 509         if (result)
 510                 err("usb_register failed. Error number %d", result);
 511
 512         return result;
 513 }
 514
 515 static void __exit usb_skel_exit(void)
 516 {
 517         /* deregister this driver with the USB subsystem */
 518         usb_deregister(&skel_driver);
 519 }
 520
 521 module_init(usb_skel_init);
 522 module_exit(usb_skel_exit);
 523
 524 MODULE_LICENSE("GPL");