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         /* increment our usage count for the device */
  94         kref_get(&dev->kref);
  95
  96         /* prevent the device from being autosuspended */
  97         retval = usb_autopm_get_interface(interface);
  98         if (retval) {
  99                 kref_put(&dev->kref, skel_delete);
 100                 goto exit;
 101         }
 102
 103         /* save our object in the file's private structure */
 104         file->private_data = dev;
 105
 106 exit:
 107         return retval;
 108 }
 109
 110 static int skel_release(struct inode *inode, struct file *file)
 111 {
 112         struct usb_skel *dev;
 113
 114         dev = (struct usb_skel *)file->private_data;
 115         if (dev == NULL)
 116                 return -ENODEV;
 117
 118         /* allow the device to be autosuspended */
 119         mutex_lock(&dev->io_mutex);
 120         if (dev->interface)
 121                 usb_autopm_put_interface(dev->interface);
 122         mutex_unlock(&dev->io_mutex);
 123
 124         /* decrement the count on our device */
 125         kref_put(&dev->kref, skel_delete);
 126         return 0;
 127 }
 128
 129 static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos)
 130 {
 131         struct usb_skel *dev;
 132         int retval;
 133         int bytes_read;
 134
 135         dev = (struct usb_skel *)file->private_data;
 136
 137         mutex_lock(&dev->io_mutex);
 138         if (!dev->interface) {          /* disconnect() was called */
 139                 retval = -ENODEV;
 140                 goto exit;
 141         }
 142
 143         /* do a blocking bulk read to get data from the device */
 144         retval = usb_bulk_msg(dev->udev,
 145                               usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
 146                               dev->bulk_in_buffer,
 147                               min(dev->bulk_in_size, count),
 148                               &bytes_read, 10000);
 149
 150         /* if the read was successful, copy the data to userspace */
 151         if (!retval) {
 152                 if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
 153                         retval = -EFAULT;
 154                 else
 155                         retval = bytes_read;
 156         }
 157
 158 exit:
 159         mutex_unlock(&dev->io_mutex);
 160         return retval;
 161 }
 162
 163 static void skel_write_bulk_callback(struct urb *urb)
 164 {
 165         struct usb_skel *dev;
 166
 167         dev = (struct usb_skel *)urb->context;
 168
 169         /* sync/async unlink faults aren't errors */
 170         if (urb->status &&
 171             !(urb->status == -ENOENT ||
 172               urb->status == -ECONNRESET ||
 173               urb->status == -ESHUTDOWN)) {
 174                 err("%s - nonzero write bulk status received: %d",
 175                     __FUNCTION__, urb->status);
 176         }
 177
 178         /* free up our allocated buffer */
 179         usb_buffer_free(urb->dev, urb->transfer_buffer_length,
 180                         urb->transfer_buffer, urb->transfer_dma);
 181         up(&dev->limit_sem);
 182 }
 183
 184 static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos)
 185 {
 186         struct usb_skel *dev;
 187         int retval = 0;
 188         struct urb *urb = NULL;
 189         char *buf = NULL;
 190         size_t writesize = min(count, (size_t)MAX_TRANSFER);
 191
 192         dev = (struct usb_skel *)file->private_data;
 193
 194         /* verify that we actually have some data to write */
 195         if (count == 0)
 196                 goto exit;
 197
 198         /* limit the number of URBs in flight to stop a user from using up all RAM */
 199         if (down_interruptible(&dev->limit_sem)) {
 200                 retval = -ERESTARTSYS;
 201                 goto exit;
 202         }
 203
 204         mutex_lock(&dev->io_mutex);
 205         if (!dev->interface) {          /* disconnect() was called */
 206                 retval = -ENODEV;
 207                 goto error;
 208         }
 209
 210         /* create a urb, and a buffer for it, and copy the data to the urb */
 211         urb = usb_alloc_urb(0, GFP_KERNEL);
 212         if (!urb) {
 213                 retval = -ENOMEM;
 214                 goto error;
 215         }
 216
 217         buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma);
 218         if (!buf) {
 219                 retval = -ENOMEM;
 220                 goto error;
 221         }
 222
 223         if (copy_from_user(buf, user_buffer, writesize)) {
 224                 retval = -EFAULT;
 225                 goto error;
 226         }
 227
 228         /* initialize the urb properly */
 229         usb_fill_bulk_urb(urb, dev->udev,
 230                           usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
 231                           buf, writesize, skel_write_bulk_callback, dev);
 232         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 233
 234         /* send the data out the bulk port */
 235         retval = usb_submit_urb(urb, GFP_KERNEL);
 236         if (retval) {
 237                 err("%s - failed submitting write urb, error %d", __FUNCTION__, retval);
 238                 goto error;
 239         }
 240
 241         /* release our reference to this urb, the USB core will eventually free it entirely */
 242         usb_free_urb(urb);
 243
 244         mutex_unlock(&dev->io_mutex);
 245         return writesize;
 246
 247 error:
 248         if (urb) {
 249                 usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
 250                 usb_free_urb(urb);
 251         }
 252         mutex_unlock(&dev->io_mutex);
 253         up(&dev->limit_sem);
 254
 255 exit:
 256         return retval;
 257 }
 258
 259 static const struct file_operations skel_fops = {
 260         .owner =        THIS_MODULE,
 261         .read =         skel_read,
 262         .write =        skel_write,
 263         .open =         skel_open,
 264         .release =      skel_release,
 265 };
 266
 267 /*
 268  * usb class driver info in order to get a minor number from the usb core,
 269  * and to have the device registered with the driver core
 270  */
 271 static struct usb_class_driver skel_class = {
 272         .name =         "skel%d",
 273         .fops =         &skel_fops,
 274         .minor_base =   USB_SKEL_MINOR_BASE,
 275 };
 276
 277 static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id)
 278 {
 279         struct usb_skel *dev;
 280         struct usb_host_interface *iface_desc;
 281         struct usb_endpoint_descriptor *endpoint;
 282         size_t buffer_size;
 283         int i;
 284         int retval = -ENOMEM;
 285
 286         /* allocate memory for our device state and initialize it */
 287         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 288         if (!dev) {
 289                 err("Out of memory");
 290                 goto error;
 291         }
 292         kref_init(&dev->kref);
 293         sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
 294         mutex_init(&dev->io_mutex);
 295
 296         dev->udev = usb_get_dev(interface_to_usbdev(interface));
 297         dev->interface = interface;
 298
 299         /* set up the endpoint information */
 300         /* use only the first bulk-in and bulk-out endpoints */
 301         iface_desc = interface->cur_altsetting;
 302         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 303                 endpoint = &iface_desc->endpoint[i].desc;
 304
 305                 if (!dev->bulk_in_endpointAddr &&
 306                     usb_endpoint_is_bulk_in(endpoint)) {
 307                         /* we found a bulk in endpoint */
 308                         buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
 309                         dev->bulk_in_size = buffer_size;
 310                         dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
 311                         dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
 312                         if (!dev->bulk_in_buffer) {
 313                                 err("Could not allocate bulk_in_buffer");
 314                                 goto error;
 315                         }
 316                 }
 317
 318                 if (!dev->bulk_out_endpointAddr &&
 319                     usb_endpoint_is_bulk_out(endpoint)) {
 320                         /* we found a bulk out endpoint */
 321                         dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
 322                 }
 323         }
 324         if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
 325                 err("Could not find both bulk-in and bulk-out endpoints");
 326                 goto error;
 327         }
 328
 329         /* save our data pointer in this interface device */
 330         usb_set_intfdata(interface, dev);
 331
 332         /* we can register the device now, as it is ready */
 333         retval = usb_register_dev(interface, &skel_class);
 334         if (retval) {
 335                 /* something prevented us from registering this driver */
 336                 err("Not able to get a minor for this device.");
 337                 usb_set_intfdata(interface, NULL);
 338                 goto error;
 339         }
 340
 341         /* let the user know what node this device is now attached to */
 342         info("USB Skeleton device now attached to USBSkel-%d", interface->minor);
 343         return 0;
 344
 345 error:
 346         if (dev)
 347                 kref_put(&dev->kref, skel_delete);
 348         return retval;
 349 }
 350
 351 static void skel_disconnect(struct usb_interface *interface)
 352 {
 353         struct usb_skel *dev;
 354         int minor = interface->minor;
 355
 356         /* prevent skel_open() from racing skel_disconnect() */
 357         lock_kernel();
 358
 359         dev = usb_get_intfdata(interface);
 360         usb_set_intfdata(interface, NULL);
 361
 362         /* give back our minor */
 363         usb_deregister_dev(interface, &skel_class);
 364
 365         /* prevent more I/O from starting */
 366         mutex_lock(&dev->io_mutex);
 367         dev->interface = NULL;
 368         mutex_unlock(&dev->io_mutex);
 369
 370         unlock_kernel();
 371
 372         /* decrement our usage count */
 373         kref_put(&dev->kref, skel_delete);
 374
 375         info("USB Skeleton #%d now disconnected", minor);
 376 }
 377
 378 static struct usb_driver skel_driver = {
 379         .name =         "skeleton",
 380         .probe =        skel_probe,
 381         .disconnect =   skel_disconnect,
 382         .id_table =     skel_table,
 383 };
 384
 385 static int __init usb_skel_init(void)
 386 {
 387         int result;
 388
 389         /* register this driver with the USB subsystem */
 390         result = usb_register(&skel_driver);
 391         if (result)
 392                 err("usb_register failed. Error number %d", result);
 393
 394         return result;
 395 }
 396
 397 static void __exit usb_skel_exit(void)
 398 {
 399         /* deregister this driver with the USB subsystem */
 400         usb_deregister(&skel_driver);
 401 }
 402
 403 module_init(usb_skel_init);
 404 module_exit(usb_skel_exit);
 405
 406 MODULE_LICENSE("GPL");