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 #define WRITES_IN_FLIGHT        8
  44
  45 /* Structure to hold all of our device specific stuff */
  46 struct usb_skel {
  47         struct usb_device       *dev;                   /* the usb device for this device */
  48         struct usb_interface    *interface;             /* the interface for this device */
  49         struct semaphore        limit_sem;              /* limiting the number of writes in progress */
  50         unsigned char           *bulk_in_buffer;        /* the buffer to receive data */
  51         size_t                  bulk_in_size;           /* the size of the receive buffer */
  52         __u8                    bulk_in_endpointAddr;   /* the address of the bulk in endpoint */
  53         __u8                    bulk_out_endpointAddr;  /* the address of the bulk out endpoint */
  54         struct kref             kref;
  55         struct mutex            io_mutex;               /* synchronize I/O with disconnect */
  56 };
  57 #define to_skel_dev(d) container_of(d, struct usb_skel, kref)
  58
  59 static struct usb_driver skel_driver;
  60
  61 static void skel_delete(struct kref *kref)
  62 {
  63         struct usb_skel *dev = to_skel_dev(kref);
  64
  65         usb_put_dev(dev->udev);
  66         kfree(dev->bulk_in_buffer);
  67         kfree(dev);
  68 }
  69
  70 static int skel_open(struct inode *inode, struct file *file)
  71 {
  72         struct usb_skel *dev;
  73         struct usb_interface *interface;
  74         int subminor;
  75         int retval = 0;
  76
  77         subminor = iminor(inode);
  78
  79         interface = usb_find_interface(&skel_driver, subminor);
  80         if (!interface) {
  81                 err ("%s - error, can't find device for minor %d",
  82                      __FUNCTION__, subminor);
  83                 retval = -ENODEV;
  84                 goto exit;
  85         }
  86
  87         dev = usb_get_intfdata(interface);
  88         if (!dev) {
  89                 retval = -ENODEV;
  90                 goto exit;
  91         }
  92
  93         /* prevent the device from being autosuspended */
  94         retval = usb_autopm_get_interface(interface);
  95         if (retval)
  96                 goto exit;
  97
  98         /* increment our usage count for the device */
  99         kref_get(&dev->kref);
 100
 101         /* save our object in the file's private structure */
 102         file->private_data = dev;
 103
 104 exit:
 105         return retval;
 106 }
 107
 108 static int skel_release(struct inode *inode, struct file *file)
 109 {
 110         struct usb_skel *dev;
 111
 112         dev = (struct usb_skel *)file->private_data;
 113         if (dev == NULL)
 114                 return -ENODEV;
 115
 116         /* allow the device to be autosuspended */
 117         mutex_lock(&dev->io_mutex);
 118         if (dev->interface)
 119                 usb_autopm_put_interface(dev->interface);
 120         mutex_unlock(&dev->io_mutex);
 121
 122         /* decrement the count on our device */
 123         kref_put(&dev->kref, skel_delete);
 124         return 0;
 125 }
 126
 127 static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos)
 128 {
 129         struct usb_skel *dev;
 130         int retval;
 131         int bytes_read;
 132
 133         dev = (struct usb_skel *)file->private_data;
 134
 135         mutex_lock(&dev->io_mutex);
 136         if (!dev->interface) {          /* disconnect() was called */
 137                 retval = -ENODEV;
 138                 goto exit;
 139         }
 140
 141         /* do a blocking bulk read to get data from the device */
 142         retval = usb_bulk_msg(dev->udev,
 143                               usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
 144                               dev->bulk_in_buffer,
 145                               min(dev->bulk_in_size, count),
 146                               &bytes_read, 10000);
 147
 148         /* if the read was successful, copy the data to userspace */
 149         if (!retval) {
 150                 if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
 151                         retval = -EFAULT;
 152                 else
 153                         retval = bytes_read;
 154         }
 155
 156 exit:
 157         mutex_unlock(&dev->io_mutex);
 158         return retval;
 159 }
 160
 161 static void skel_write_bulk_callback(struct urb *urb, struct pt_regs *regs)
 162 {
 163         struct usb_skel *dev;
 164
 165         dev = (struct usb_skel *)urb->context;
 166
 167         /* sync/async unlink faults aren't errors */
 168         if (urb->status &&
 169             !(urb->status == -ENOENT ||
 170               urb->status == -ECONNRESET ||
 171               urb->status == -ESHUTDOWN)) {
 172                 err("%s - nonzero write bulk status received: %d",
 173                     __FUNCTION__, urb->status);
 174         }
 175
 176         /* free up our allocated buffer */
 177         usb_buffer_free(urb->dev, urb->transfer_buffer_length,
 178                         urb->transfer_buffer, urb->transfer_dma);
 179         up(&dev->limit_sem);
 180 }
 181
 182 static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos)
 183 {
 184         struct usb_skel *dev;
 185         int retval = 0;
 186         struct urb *urb = NULL;
 187         char *buf = NULL;
 188         size_t writesize = min(count, (size_t)MAX_TRANSFER);
 189
 190         dev = (struct usb_skel *)file->private_data;
 191
 192         /* verify that we actually have some data to write */
 193         if (count == 0)
 194                 goto exit;
 195
 196         /* limit the number of URBs in flight to stop a user from using up all RAM */
 197         if (down_interruptible(&dev->limit_sem)) {
 198                 retval = -ERESTARTSYS;
 199                 goto exit;
 200         }
 201
 202         mutex_lock(&dev->io_mutex);
 203         if (!dev->interface) {          /* disconnect() was called */
 204                 retval = -ENODEV;
 205                 goto error;
 206         }
 207
 208         /* create a urb, and a buffer for it, and copy the data to the urb */
 209         urb = usb_alloc_urb(0, GFP_KERNEL);
 210         if (!urb) {
 211                 retval = -ENOMEM;
 212                 goto error;
 213         }
 214
 215         buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma);
 216         if (!buf) {
 217                 retval = -ENOMEM;
 218                 goto error;
 219         }
 220
 221         if (copy_from_user(buf, user_buffer, writesize)) {
 222                 retval = -EFAULT;
 223                 goto error;
 224         }
 225
 226         /* initialize the urb properly */
 227         usb_fill_bulk_urb(urb, dev->udev,
 228                           usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
 229                           buf, writesize, skel_write_bulk_callback, dev);
 230         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 231
 232         /* send the data out the bulk port */
 233         retval = usb_submit_urb(urb, GFP_KERNEL);
 234         if (retval) {
 235                 err("%s - failed submitting write urb, error %d", __FUNCTION__, retval);
 236                 goto error;
 237         }
 238
 239         /* release our reference to this urb, the USB core will eventually free it entirely */
 240         usb_free_urb(urb);
 241
 242         mutex_unlock(&dev->io_mutex);
 243         return writesize;
 244
 245 error:
 246         if (urb) {
 247                 usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
 248                 usb_free_urb(urb);
 249         }
 250         mutex_unlock(&dev->io_mutex);
 251         up(&dev->limit_sem);
 252
 253 exit:
 254         return retval;
 255 }
 256
 257 static const struct file_operations skel_fops = {
 258         .owner =        THIS_MODULE,
 259         .read =         skel_read,
 260         .write =        skel_write,
 261         .open =         skel_open,
 262         .release =      skel_release,
 263 };
 264
 265 /*
 266  * usb class driver info in order to get a minor number from the usb core,
 267  * and to have the device registered with the driver core
 268  */
 269 static struct usb_class_driver skel_class = {
 270         .name =         "skel%d",
 271         .fops =         &skel_fops,
 272         .minor_base =   USB_SKEL_MINOR_BASE,
 273 };
 274
 275 static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id)
 276 {
 277         struct usb_skel *dev;
 278         struct usb_host_interface *iface_desc;
 279         struct usb_endpoint_descriptor *endpoint;
 280         size_t buffer_size;
 281         int i;
 282         int retval = -ENOMEM;
 283
 284         /* allocate memory for our device state and initialize it */
 285         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 286         if (!dev) {
 287                 err("Out of memory");
 288                 goto error;
 289         }
 290         kref_init(&dev->kref);
 291         sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
 292         mutex_init(&dev->io_mutex);
 293
 294         dev->udev = usb_get_dev(interface_to_usbdev(interface));
 295         dev->interface = interface;
 296
 297         /* set up the endpoint information */
 298         /* use only the first bulk-in and bulk-out endpoints */
 299         iface_desc = interface->cur_altsetting;
 300         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 301                 endpoint = &iface_desc->endpoint[i].desc;
 302
 303                 if (!dev->bulk_in_endpointAddr &&
 304                     usb_endpoint_is_bulk_in(endpoint)) {
 305                         /* we found a bulk in endpoint */
 306                         buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
 307                         dev->bulk_in_size = buffer_size;
 308                         dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
 309                         dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
 310                         if (!dev->bulk_in_buffer) {
 311                                 err("Could not allocate bulk_in_buffer");
 312                                 goto error;
 313                         }
 314                 }
 315
 316                 if (!dev->bulk_out_endpointAddr &&
 317                     usb_endpoint_is_bulk_out(endpoint)) {
 318                         /* we found a bulk out endpoint */
 319                         dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
 320                 }
 321         }
 322         if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
 323                 err("Could not find both bulk-in and bulk-out endpoints");
 324                 goto error;
 325         }
 326
 327         /* save our data pointer in this interface device */
 328         usb_set_intfdata(interface, dev);
 329
 330         /* we can register the device now, as it is ready */
 331         retval = usb_register_dev(interface, &skel_class);
 332         if (retval) {
 333                 /* something prevented us from registering this driver */
 334                 err("Not able to get a minor for this device.");
 335                 usb_set_intfdata(interface, NULL);
 336                 goto error;
 337         }
 338
 339         /* let the user know what node this device is now attached to */
 340         info("USB Skeleton device now attached to USBSkel-%d", interface->minor);
 341         return 0;
 342
 343 error:
 344         if (dev)
 345                 kref_put(&dev->kref, skel_delete);
 346         return retval;
 347 }
 348
 349 static void skel_disconnect(struct usb_interface *interface)
 350 {
 351         struct usb_skel *dev;
 352         int minor = interface->minor;
 353
 354         /* prevent skel_open() from racing skel_disconnect() */
 355         lock_kernel();
 356
 357         dev = usb_get_intfdata(interface);
 358         usb_set_intfdata(interface, NULL);
 359
 360         /* give back our minor */
 361         usb_deregister_dev(interface, &skel_class);
 362
 363         /* prevent more I/O from starting */
 364         mutex_lock(&dev->io_mutex);
 365         dev->interface = NULL;
 366         mutex_unlock(&dev->io_mutex);
 367
 368         unlock_kernel();
 369
 370         /* decrement our usage count */
 371         kref_put(&dev->kref, skel_delete);
 372
 373         info("USB Skeleton #%d now disconnected", minor);
 374 }
 375
 376 static struct usb_driver skel_driver = {
 377         .name =         "skeleton",
 378         .probe =        skel_probe,
 379         .disconnect =   skel_disconnect,
 380         .id_table =     skel_table,
 381 };
 382
 383 static int __init usb_skel_init(void)
 384 {
 385         int result;
 386
 387         /* register this driver with the USB subsystem */
 388         result = usb_register(&skel_driver);
 389         if (result)
 390                 err("usb_register failed. Error number %d", result);
 391
 392         return result;
 393 }
 394
 395 static void __exit usb_skel_exit(void)
 396 {
 397         /* deregister this driver with the USB subsystem */
 398         usb_deregister(&skel_driver);
 399 }
 400
 401 module_init(usb_skel_init);
 402 module_exit(usb_skel_exit);
 403
 404 MODULE_LICENSE("GPL");