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                      __func__, 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         mutex_unlock(&dev->io_mutex);
 129
 130 exit:
 131         return retval;
 132 }
 133
 134 static int skel_release(struct inode *inode, struct file *file)
 135 {
 136         struct usb_skel *dev;
 137
 138         dev = (struct usb_skel *)file->private_data;
 139         if (dev == NULL)
 140                 return -ENODEV;
 141
 142         /* allow the device to be autosuspended */
 143         mutex_lock(&dev->io_mutex);
 144         if (!--dev->open_count && dev->interface)
 145                 usb_autopm_put_interface(dev->interface);
 146         mutex_unlock(&dev->io_mutex);
 147
 148         /* decrement the count on our device */
 149         kref_put(&dev->kref, skel_delete);
 150         return 0;
 151 }
 152
 153 static int skel_flush(struct file *file, fl_owner_t id)
 154 {
 155         struct usb_skel *dev;
 156         int res;
 157
 158         dev = (struct usb_skel *)file->private_data;
 159         if (dev == NULL)
 160                 return -ENODEV;
 161
 162         /* wait for io to stop */
 163         mutex_lock(&dev->io_mutex);
 164         skel_draw_down(dev);
 165
 166         /* read out errors, leave subsequent opens a clean slate */
 167         spin_lock_irq(&dev->err_lock);
 168         res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
 169         dev->errors = 0;
 170         spin_unlock_irq(&dev->err_lock);
 171
 172         mutex_unlock(&dev->io_mutex);
 173
 174         return res;
 175 }
 176
 177 static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos)
 178 {
 179         struct usb_skel *dev;
 180         int retval;
 181         int bytes_read;
 182
 183         dev = (struct usb_skel *)file->private_data;
 184
 185         mutex_lock(&dev->io_mutex);
 186         if (!dev->interface) {          /* disconnect() was called */
 187                 retval = -ENODEV;
 188                 goto exit;
 189         }
 190
 191         /* do a blocking bulk read to get data from the device */
 192         retval = usb_bulk_msg(dev->udev,
 193                               usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
 194                               dev->bulk_in_buffer,
 195                               min(dev->bulk_in_size, count),
 196                               &bytes_read, 10000);
 197
 198         /* if the read was successful, copy the data to userspace */
 199         if (!retval) {
 200                 if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
 201                         retval = -EFAULT;
 202                 else
 203                         retval = bytes_read;
 204         }
 205
 206 exit:
 207         mutex_unlock(&dev->io_mutex);
 208         return retval;
 209 }
 210
 211 static void skel_write_bulk_callback(struct urb *urb)
 212 {
 213         struct usb_skel *dev;
 214
 215         dev = urb->context;
 216
 217         /* sync/async unlink faults aren't errors */
 218         if (urb->status) {
 219                 if(!(urb->status == -ENOENT ||
 220                     urb->status == -ECONNRESET ||
 221                     urb->status == -ESHUTDOWN))
 222                         err("%s - nonzero write bulk status received: %d",
 223                             __func__, urb->status);
 224
 225                 spin_lock(&dev->err_lock);
 226                 dev->errors = urb->status;
 227                 spin_unlock(&dev->err_lock);
 228         }
 229
 230         /* free up our allocated buffer */
 231         usb_buffer_free(urb->dev, urb->transfer_buffer_length,
 232                         urb->transfer_buffer, urb->transfer_dma);
 233         up(&dev->limit_sem);
 234 }
 235
 236 static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos)
 237 {
 238         struct usb_skel *dev;
 239         int retval = 0;
 240         struct urb *urb = NULL;
 241         char *buf = NULL;
 242         size_t writesize = min(count, (size_t)MAX_TRANSFER);
 243
 244         dev = (struct usb_skel *)file->private_data;
 245
 246         /* verify that we actually have some data to write */
 247         if (count == 0)
 248                 goto exit;
 249
 250         /* limit the number of URBs in flight to stop a user from using up all RAM */
 251         if (down_interruptible(&dev->limit_sem)) {
 252                 retval = -ERESTARTSYS;
 253                 goto exit;
 254         }
 255
 256         spin_lock_irq(&dev->err_lock);
 257         if ((retval = dev->errors) < 0) {
 258                 /* any error is reported once */
 259                 dev->errors = 0;
 260                 /* to preserve notifications about reset */
 261                 retval = (retval == -EPIPE) ? retval : -EIO;
 262         }
 263         spin_unlock_irq(&dev->err_lock);
 264         if (retval < 0)
 265                 goto error;
 266
 267         /* create a urb, and a buffer for it, and copy the data to the urb */
 268         urb = usb_alloc_urb(0, GFP_KERNEL);
 269         if (!urb) {
 270                 retval = -ENOMEM;
 271                 goto error;
 272         }
 273
 274         buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma);
 275         if (!buf) {
 276                 retval = -ENOMEM;
 277                 goto error;
 278         }
 279
 280         if (copy_from_user(buf, user_buffer, writesize)) {
 281                 retval = -EFAULT;
 282                 goto error;
 283         }
 284
 285         /* this lock makes sure we don't submit URBs to gone devices */
 286         mutex_lock(&dev->io_mutex);
 287         if (!dev->interface) {          /* disconnect() was called */
 288                 mutex_unlock(&dev->io_mutex);
 289                 retval = -ENODEV;
 290                 goto error;
 291         }
 292
 293         /* initialize the urb properly */
 294         usb_fill_bulk_urb(urb, dev->udev,
 295                           usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
 296                           buf, writesize, skel_write_bulk_callback, dev);
 297         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 298         usb_anchor_urb(urb, &dev->submitted);
 299
 300         /* send the data out the bulk port */
 301         retval = usb_submit_urb(urb, GFP_KERNEL);
 302         mutex_unlock(&dev->io_mutex);
 303         if (retval) {
 304                 err("%s - failed submitting write urb, error %d", __func__, retval);
 305                 goto error_unanchor;
 306         }
 307
 308         /* release our reference to this urb, the USB core will eventually free it entirely */
 309         usb_free_urb(urb);
 310
 311
 312         return writesize;
 313
 314 error_unanchor:
 315         usb_unanchor_urb(urb);
 316 error:
 317         if (urb) {
 318                 usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
 319                 usb_free_urb(urb);
 320         }
 321         up(&dev->limit_sem);
 322
 323 exit:
 324         return retval;
 325 }
 326
 327 static const struct file_operations skel_fops = {
 328         .owner =        THIS_MODULE,
 329         .read =         skel_read,
 330         .write =        skel_write,
 331         .open =         skel_open,
 332         .release =      skel_release,
 333         .flush =        skel_flush,
 334 };
 335
 336 /*
 337  * usb class driver info in order to get a minor number from the usb core,
 338  * and to have the device registered with the driver core
 339  */
 340 static struct usb_class_driver skel_class = {
 341         .name =         "skel%d",
 342         .fops =         &skel_fops,
 343         .minor_base =   USB_SKEL_MINOR_BASE,
 344 };
 345
 346 static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id)
 347 {
 348         struct usb_skel *dev;
 349         struct usb_host_interface *iface_desc;
 350         struct usb_endpoint_descriptor *endpoint;
 351         size_t buffer_size;
 352         int i;
 353         int retval = -ENOMEM;
 354
 355         /* allocate memory for our device state and initialize it */
 356         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 357         if (!dev) {
 358                 err("Out of memory");
 359                 goto error;
 360         }
 361         kref_init(&dev->kref);
 362         sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
 363         mutex_init(&dev->io_mutex);
 364         spin_lock_init(&dev->err_lock);
 365         init_usb_anchor(&dev->submitted);
 366
 367         dev->udev = usb_get_dev(interface_to_usbdev(interface));
 368         dev->interface = interface;
 369
 370         /* set up the endpoint information */
 371         /* use only the first bulk-in and bulk-out endpoints */
 372         iface_desc = interface->cur_altsetting;
 373         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 374                 endpoint = &iface_desc->endpoint[i].desc;
 375
 376                 if (!dev->bulk_in_endpointAddr &&
 377                     usb_endpoint_is_bulk_in(endpoint)) {
 378                         /* we found a bulk in endpoint */
 379                         buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
 380                         dev->bulk_in_size = buffer_size;
 381                         dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
 382                         dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
 383                         if (!dev->bulk_in_buffer) {
 384                                 err("Could not allocate bulk_in_buffer");
 385                                 goto error;
 386                         }
 387                 }
 388
 389                 if (!dev->bulk_out_endpointAddr &&
 390                     usb_endpoint_is_bulk_out(endpoint)) {
 391                         /* we found a bulk out endpoint */
 392                         dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
 393                 }
 394         }
 395         if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
 396                 err("Could not find both bulk-in and bulk-out endpoints");
 397                 goto error;
 398         }
 399
 400         /* save our data pointer in this interface device */
 401         usb_set_intfdata(interface, dev);
 402
 403         /* we can register the device now, as it is ready */
 404         retval = usb_register_dev(interface, &skel_class);
 405         if (retval) {
 406                 /* something prevented us from registering this driver */
 407                 err("Not able to get a minor for this device.");
 408                 usb_set_intfdata(interface, NULL);
 409                 goto error;
 410         }
 411
 412         /* let the user know what node this device is now attached to */
 413         info("USB Skeleton device now attached to USBSkel-%d", interface->minor);
 414         return 0;
 415
 416 error:
 417         if (dev)
 418                 /* this frees allocated memory */
 419                 kref_put(&dev->kref, skel_delete);
 420         return retval;
 421 }
 422
 423 static void skel_disconnect(struct usb_interface *interface)
 424 {
 425         struct usb_skel *dev;
 426         int minor = interface->minor;
 427
 428         dev = usb_get_intfdata(interface);
 429         usb_set_intfdata(interface, NULL);
 430
 431         /* give back our minor */
 432         usb_deregister_dev(interface, &skel_class);
 433
 434         /* prevent more I/O from starting */
 435         mutex_lock(&dev->io_mutex);
 436         dev->interface = NULL;
 437         mutex_unlock(&dev->io_mutex);
 438
 439         usb_kill_anchored_urbs(&dev->submitted);
 440
 441         /* decrement our usage count */
 442         kref_put(&dev->kref, skel_delete);
 443
 444         info("USB Skeleton #%d now disconnected", minor);
 445 }
 446
 447 static void skel_draw_down(struct usb_skel *dev)
 448 {
 449         int time;
 450
 451         time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
 452         if (!time)
 453                 usb_kill_anchored_urbs(&dev->submitted);
 454 }
 455
 456 static int skel_suspend(struct usb_interface *intf, pm_message_t message)
 457 {
 458         struct usb_skel *dev = usb_get_intfdata(intf);
 459
 460         if (!dev)
 461                 return 0;
 462         skel_draw_down(dev);
 463         return 0;
 464 }
 465
 466 static int skel_resume (struct usb_interface *intf)
 467 {
 468         return 0;
 469 }
 470
 471 static int skel_pre_reset(struct usb_interface *intf)
 472 {
 473         struct usb_skel *dev = usb_get_intfdata(intf);
 474
 475         mutex_lock(&dev->io_mutex);
 476         skel_draw_down(dev);
 477
 478         return 0;
 479 }
 480
 481 static int skel_post_reset(struct usb_interface *intf)
 482 {
 483         struct usb_skel *dev = usb_get_intfdata(intf);
 484
 485         /* we are sure no URBs are active - no locking needed */
 486         dev->errors = -EPIPE;
 487         mutex_unlock(&dev->io_mutex);
 488
 489         return 0;
 490 }
 491
 492 static struct usb_driver skel_driver = {
 493         .name =         "skeleton",
 494         .probe =        skel_probe,
 495         .disconnect =   skel_disconnect,
 496         .suspend =      skel_suspend,
 497         .resume =       skel_resume,
 498         .pre_reset =    skel_pre_reset,
 499         .post_reset =   skel_post_reset,
 500         .id_table =     skel_table,
 501         .supports_autosuspend = 1,
 502 };
 503
 504 static int __init usb_skel_init(void)
 505 {
 506         int result;
 507
 508         /* register this driver with the USB subsystem */
 509         result = usb_register(&skel_driver);
 510         if (result)
 511                 err("usb_register failed. Error number %d", result);
 512
 513         return result;
 514 }
 515
 516 static void __exit usb_skel_exit(void)
 517 {
 518         /* deregister this driver with the USB subsystem */
 519         usb_deregister(&skel_driver);
 520 }
 521
 522 module_init(usb_skel_init);
 523 module_exit(usb_skel_exit);
 524
 525 MODULE_LICENSE("GPL");