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 /* to prevent a race between open and disconnect */
  38 static DEFINE_MUTEX(skel_open_lock);
  39
  40
  41 /* Get a minor range for your devices from the usb maintainer */
  42 #define USB_SKEL_MINOR_BASE     192
  43
  44 /* our private defines. if this grows any larger, use your own .h file */
  45 #define MAX_TRANSFER            (PAGE_SIZE - 512)
  46 /* MAX_TRANSFER is chosen so that the VM is not stressed by
  47    allocations > PAGE_SIZE and the number of packets in a page
  48    is an integer 512 is the largest possible packet on EHCI */
  49 #define WRITES_IN_FLIGHT        8
  50 /* arbitrarily chosen */
  51
  52 /* Structure to hold all of our device specific stuff */
  53 struct usb_skel {
  54         struct usb_device       *udev;                  /* the usb device for this device */
  55         struct usb_interface    *interface;             /* the interface for this device */
  56         struct semaphore        limit_sem;              /* limiting the number of writes in progress */
  57         unsigned char           *bulk_in_buffer;        /* the buffer to receive data */
  58         size_t                  bulk_in_size;           /* the size of the receive buffer */
  59         __u8                    bulk_in_endpointAddr;   /* the address of the bulk in endpoint */
  60         __u8                    bulk_out_endpointAddr;  /* the address of the bulk out endpoint */
  61         struct kref             kref;
  62         struct mutex            io_mutex;               /* synchronize I/O with disconnect */
  63 };
  64 #define to_skel_dev(d) container_of(d, struct usb_skel, kref)
  65
  66 static struct usb_driver skel_driver;
  67
  68 static void skel_delete(struct kref *kref)
  69 {
  70         struct usb_skel *dev = to_skel_dev(kref);
  71
  72         usb_put_dev(dev->udev);
  73         kfree(dev->bulk_in_buffer);
  74         kfree(dev);
  75 }
  76
  77 static int skel_open(struct inode *inode, struct file *file)
  78 {
  79         struct usb_skel *dev;
  80         struct usb_interface *interface;
  81         int subminor;
  82         int retval = 0;
  83
  84         subminor = iminor(inode);
  85
  86         mutex_lock(&skel_open_lock);
  87         interface = usb_find_interface(&skel_driver, subminor);
  88         if (!interface) {
  89                 mutex_unlock(&skel_open_lock);
  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                 mutex_unlock(&skel_open_lock);
  99                 retval = -ENODEV;
 100                 goto exit;
 101         }
 102
 103         /* increment our usage count for the device */
 104         kref_get(&dev->kref);
 105         /* now we can drop the lock */
 106         mutex_unlock(&skel_open_lock);
 107
 108         /* prevent the device from being autosuspended */
 109         retval = usb_autopm_get_interface(interface);
 110         if (retval) {
 111                 kref_put(&dev->kref, skel_delete);
 112                 goto exit;
 113         }
 114
 115         /* save our object in the file's private structure */
 116         file->private_data = dev;
 117
 118 exit:
 119         return retval;
 120 }
 121
 122 static int skel_release(struct inode *inode, struct file *file)
 123 {
 124         struct usb_skel *dev;
 125
 126         dev = (struct usb_skel *)file->private_data;
 127         if (dev == NULL)
 128                 return -ENODEV;
 129
 130         /* allow the device to be autosuspended */
 131         mutex_lock(&dev->io_mutex);
 132         if (dev->interface)
 133                 usb_autopm_put_interface(dev->interface);
 134         mutex_unlock(&dev->io_mutex);
 135
 136         /* decrement the count on our device */
 137         kref_put(&dev->kref, skel_delete);
 138         return 0;
 139 }
 140
 141 static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos)
 142 {
 143         struct usb_skel *dev;
 144         int retval;
 145         int bytes_read;
 146
 147         dev = (struct usb_skel *)file->private_data;
 148
 149         mutex_lock(&dev->io_mutex);
 150         if (!dev->interface) {          /* disconnect() was called */
 151                 retval = -ENODEV;
 152                 goto exit;
 153         }
 154
 155         /* do a blocking bulk read to get data from the device */
 156         retval = usb_bulk_msg(dev->udev,
 157                               usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
 158                               dev->bulk_in_buffer,
 159                               min(dev->bulk_in_size, count),
 160                               &bytes_read, 10000);
 161
 162         /* if the read was successful, copy the data to userspace */
 163         if (!retval) {
 164                 if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
 165                         retval = -EFAULT;
 166                 else
 167                         retval = bytes_read;
 168         }
 169
 170 exit:
 171         mutex_unlock(&dev->io_mutex);
 172         return retval;
 173 }
 174
 175 static void skel_write_bulk_callback(struct urb *urb)
 176 {
 177         struct usb_skel *dev;
 178
 179         dev = (struct usb_skel *)urb->context;
 180
 181         /* sync/async unlink faults aren't errors */
 182         if (urb->status &&
 183             !(urb->status == -ENOENT ||
 184               urb->status == -ECONNRESET ||
 185               urb->status == -ESHUTDOWN)) {
 186                 err("%s - nonzero write bulk status received: %d",
 187                     __FUNCTION__, urb->status);
 188         }
 189
 190         /* free up our allocated buffer */
 191         usb_buffer_free(urb->dev, urb->transfer_buffer_length,
 192                         urb->transfer_buffer, urb->transfer_dma);
 193         up(&dev->limit_sem);
 194 }
 195
 196 static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos)
 197 {
 198         struct usb_skel *dev;
 199         int retval = 0;
 200         struct urb *urb = NULL;
 201         char *buf = NULL;
 202         size_t writesize = min(count, (size_t)MAX_TRANSFER);
 203
 204         dev = (struct usb_skel *)file->private_data;
 205
 206         /* verify that we actually have some data to write */
 207         if (count == 0)
 208                 goto exit;
 209
 210         /* limit the number of URBs in flight to stop a user from using up all RAM */
 211         if (down_interruptible(&dev->limit_sem)) {
 212                 retval = -ERESTARTSYS;
 213                 goto exit;
 214         }
 215
 216         /* create a urb, and a buffer for it, and copy the data to the urb */
 217         urb = usb_alloc_urb(0, GFP_KERNEL);
 218         if (!urb) {
 219                 retval = -ENOMEM;
 220                 goto error;
 221         }
 222
 223         buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma);
 224         if (!buf) {
 225                 retval = -ENOMEM;
 226                 goto error;
 227         }
 228
 229         if (copy_from_user(buf, user_buffer, writesize)) {
 230                 retval = -EFAULT;
 231                 goto error;
 232         }
 233
 234         /* this lock makes sure we don't submit URBs to gone devices */
 235         mutex_lock(&dev->io_mutex);
 236         if (!dev->interface) {          /* disconnect() was called */
 237                 mutex_unlock(&dev->io_mutex);
 238                 retval = -ENODEV;
 239                 goto error;
 240         }
 241
 242         /* initialize the urb properly */
 243         usb_fill_bulk_urb(urb, dev->udev,
 244                           usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
 245                           buf, writesize, skel_write_bulk_callback, dev);
 246         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 247
 248         /* send the data out the bulk port */
 249         retval = usb_submit_urb(urb, GFP_KERNEL);
 250         mutex_unlock(&dev->io_mutex);
 251         if (retval) {
 252                 err("%s - failed submitting write urb, error %d", __FUNCTION__, retval);
 253                 goto error;
 254         }
 255
 256         /* release our reference to this urb, the USB core will eventually free it entirely */
 257         usb_free_urb(urb);
 258
 259
 260         return writesize;
 261
 262 error:
 263         if (urb) {
 264                 usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
 265                 usb_free_urb(urb);
 266         }
 267         up(&dev->limit_sem);
 268
 269 exit:
 270         return retval;
 271 }
 272
 273 static const struct file_operations skel_fops = {
 274         .owner =        THIS_MODULE,
 275         .read =         skel_read,
 276         .write =        skel_write,
 277         .open =         skel_open,
 278         .release =      skel_release,
 279 };
 280
 281 /*
 282  * usb class driver info in order to get a minor number from the usb core,
 283  * and to have the device registered with the driver core
 284  */
 285 static struct usb_class_driver skel_class = {
 286         .name =         "skel%d",
 287         .fops =         &skel_fops,
 288         .minor_base =   USB_SKEL_MINOR_BASE,
 289 };
 290
 291 static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id)
 292 {
 293         struct usb_skel *dev;
 294         struct usb_host_interface *iface_desc;
 295         struct usb_endpoint_descriptor *endpoint;
 296         size_t buffer_size;
 297         int i;
 298         int retval = -ENOMEM;
 299
 300         /* allocate memory for our device state and initialize it */
 301         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 302         if (!dev) {
 303                 err("Out of memory");
 304                 goto error;
 305         }
 306         kref_init(&dev->kref);
 307         sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
 308         mutex_init(&dev->io_mutex);
 309
 310         dev->udev = usb_get_dev(interface_to_usbdev(interface));
 311         dev->interface = interface;
 312
 313         /* set up the endpoint information */
 314         /* use only the first bulk-in and bulk-out endpoints */
 315         iface_desc = interface->cur_altsetting;
 316         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 317                 endpoint = &iface_desc->endpoint[i].desc;
 318
 319                 if (!dev->bulk_in_endpointAddr &&
 320                     usb_endpoint_is_bulk_in(endpoint)) {
 321                         /* we found a bulk in endpoint */
 322                         buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
 323                         dev->bulk_in_size = buffer_size;
 324                         dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
 325                         dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
 326                         if (!dev->bulk_in_buffer) {
 327                                 err("Could not allocate bulk_in_buffer");
 328                                 goto error;
 329                         }
 330                 }
 331
 332                 if (!dev->bulk_out_endpointAddr &&
 333                     usb_endpoint_is_bulk_out(endpoint)) {
 334                         /* we found a bulk out endpoint */
 335                         dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
 336                 }
 337         }
 338         if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
 339                 err("Could not find both bulk-in and bulk-out endpoints");
 340                 goto error;
 341         }
 342
 343         /* save our data pointer in this interface device */
 344         usb_set_intfdata(interface, dev);
 345
 346         /* we can register the device now, as it is ready */
 347         retval = usb_register_dev(interface, &skel_class);
 348         if (retval) {
 349                 /* something prevented us from registering this driver */
 350                 err("Not able to get a minor for this device.");
 351                 usb_set_intfdata(interface, NULL);
 352                 goto error;
 353         }
 354
 355         /* let the user know what node this device is now attached to */
 356         info("USB Skeleton device now attached to USBSkel-%d", interface->minor);
 357         return 0;
 358
 359 error:
 360         if (dev)
 361                 /* this frees allocated memory */
 362                 kref_put(&dev->kref, skel_delete);
 363         return retval;
 364 }
 365
 366 static void skel_disconnect(struct usb_interface *interface)
 367 {
 368         struct usb_skel *dev;
 369         int minor = interface->minor;
 370
 371         /* prevent skel_open() from racing skel_disconnect() */
 372         mutex_lock(&skel_open_lock);
 373
 374         dev = usb_get_intfdata(interface);
 375         usb_set_intfdata(interface, NULL);
 376
 377         /* give back our minor */
 378         usb_deregister_dev(interface, &skel_class);
 379         mutex_unlock(&skel_open_lock);
 380
 381         /* prevent more I/O from starting */
 382         mutex_lock(&dev->io_mutex);
 383         dev->interface = NULL;
 384         mutex_unlock(&dev->io_mutex);
 385
 386
 387
 388         /* decrement our usage count */
 389         kref_put(&dev->kref, skel_delete);
 390
 391         info("USB Skeleton #%d now disconnected", minor);
 392 }
 393
 394 static struct usb_driver skel_driver = {
 395         .name =         "skeleton",
 396         .probe =        skel_probe,
 397         .disconnect =   skel_disconnect,
 398         .id_table =     skel_table,
 399         .supports_autosuspend = 1,
 400 };
 401
 402 static int __init usb_skel_init(void)
 403 {
 404         int result;
 405
 406         /* register this driver with the USB subsystem */
 407         result = usb_register(&skel_driver);
 408         if (result)
 409                 err("usb_register failed. Error number %d", result);
 410
 411         return result;
 412 }
 413
 414 static void __exit usb_skel_exit(void)
 415 {
 416         /* deregister this driver with the USB subsystem */
 417         usb_deregister(&skel_driver);
 418 }
 419
 420 module_init(usb_skel_init);
 421 module_exit(usb_skel_exit);
 422
 423 MODULE_LICENSE("GPL");