drivers/usb/usb-skeleton.c

   1 /*
   2  * USB Skeleton driver - 2.1
   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 *     udev;                   /* 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         /* save our object in the file's private structure */
  97         file->private_data = dev;
  98
  99 exit:
 100         return retval;
 101 }
 102
 103 static int skel_release(struct inode *inode, struct file *file)
 104 {
 105         struct usb_skel *dev;
 106
 107         dev = (struct usb_skel *)file->private_data;
 108         if (dev == NULL)
 109                 return -ENODEV;
 110
 111         /* decrement the count on our device */
 112         kref_put(&dev->kref, skel_delete);
 113         return 0;
 114 }
 115
 116 static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos)
 117 {
 118         struct usb_skel *dev;
 119         int retval = 0;
 120         int bytes_read;
 121
 122         dev = (struct usb_skel *)file->private_data;
 123
 124         mutex_lock(&dev->io_mutex);
 125         if (!dev->interface) {          /* disconnect() was called */
 126                 retval = -ENODEV;
 127                 goto exit;
 128         }
 129
 130         /* do a blocking bulk read to get data from the device */
 131         retval = usb_bulk_msg(dev->udev,
 132                               usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
 133                               dev->bulk_in_buffer,
 134                               min(dev->bulk_in_size, count),
 135                               &bytes_read, 10000);
 136
 137         /* if the read was successful, copy the data to userspace */
 138         if (!retval) {
 139                 if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
 140                         retval = -EFAULT;
 141                 else
 142                         retval = bytes_read;
 143         }
 144
 145 exit:
 146         mutex_unlock(&dev->io_mutex);
 147         return retval;
 148 }
 149
 150 static void skel_write_bulk_callback(struct urb *urb, struct pt_regs *regs)
 151 {
 152         struct usb_skel *dev;
 153
 154         dev = (struct usb_skel *)urb->context;
 155
 156         /* sync/async unlink faults aren't errors */
 157         if (urb->status &&
 158             !(urb->status == -ENOENT ||
 159               urb->status == -ECONNRESET ||
 160               urb->status == -ESHUTDOWN)) {
 161                 dbg("%s - nonzero write bulk status received: %d",
 162                     __FUNCTION__, urb->status);
 163         }
 164
 165         /* free up our allocated buffer */
 166         usb_buffer_free(urb->dev, urb->transfer_buffer_length,
 167                         urb->transfer_buffer, urb->transfer_dma);
 168         up(&dev->limit_sem);
 169 }
 170
 171 static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos)
 172 {
 173         struct usb_skel *dev;
 174         int retval = 0;
 175         struct urb *urb = NULL;
 176         char *buf = NULL;
 177         size_t writesize = min(count, (size_t)MAX_TRANSFER);
 178
 179         dev = (struct usb_skel *)file->private_data;
 180
 181         /* verify that we actually have some data to write */
 182         if (count == 0)
 183                 goto exit;
 184
 185         /* limit the number of URBs in flight to stop a user from using up all RAM */
 186         if (down_interruptible(&dev->limit_sem)) {
 187                 retval = -ERESTARTSYS;
 188                 goto exit;
 189         }
 190
 191         mutex_lock(&dev->io_mutex);
 192         if (!dev->interface) {          /* disconnect() was called */
 193                 retval = -ENODEV;
 194                 goto error;
 195         }
 196
 197         /* create a urb, and a buffer for it, and copy the data to the urb */
 198         urb = usb_alloc_urb(0, GFP_KERNEL);
 199         if (!urb) {
 200                 retval = -ENOMEM;
 201                 goto error;
 202         }
 203
 204         buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma);
 205         if (!buf) {
 206                 retval = -ENOMEM;
 207                 goto error;
 208         }
 209
 210         if (copy_from_user(buf, user_buffer, writesize)) {
 211                 retval = -EFAULT;
 212                 goto error;
 213         }
 214
 215         /* initialize the urb properly */
 216         usb_fill_bulk_urb(urb, dev->udev,
 217                           usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
 218                           buf, writesize, skel_write_bulk_callback, dev);
 219         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 220
 221         /* send the data out the bulk port */
 222         retval = usb_submit_urb(urb, GFP_KERNEL);
 223         if (retval) {
 224                 err("%s - failed submitting write urb, error %d", __FUNCTION__, retval);
 225                 goto error;
 226         }
 227
 228         /* release our reference to this urb, the USB core will eventually free it entirely */
 229         usb_free_urb(urb);
 230
 231         mutex_unlock(&dev->io_mutex);
 232         return writesize;
 233
 234 error:
 235         if (urb) {
 236                 usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
 237                 usb_free_urb(urb);
 238         }
 239         mutex_unlock(&dev->io_mutex);
 240         up(&dev->limit_sem);
 241
 242 exit:
 243         return retval;
 244 }
 245
 246 static const struct file_operations skel_fops = {
 247         .owner =        THIS_MODULE,
 248         .read =         skel_read,
 249         .write =        skel_write,
 250         .open =         skel_open,
 251         .release =      skel_release,
 252 };
 253
 254 /*
 255  * usb class driver info in order to get a minor number from the usb core,
 256  * and to have the device registered with the driver core
 257  */
 258 static struct usb_class_driver skel_class = {
 259         .name =         "skel%d",
 260         .fops =         &skel_fops,
 261         .minor_base =   USB_SKEL_MINOR_BASE,
 262 };
 263
 264 static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id)
 265 {
 266         struct usb_skel *dev = NULL;
 267         struct usb_host_interface *iface_desc;
 268         struct usb_endpoint_descriptor *endpoint;
 269         size_t buffer_size;
 270         int i;
 271         int retval = -ENOMEM;
 272
 273         /* allocate memory for our device state and initialize it */
 274         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 275         if (dev == NULL) {
 276                 err("Out of memory");
 277                 goto error;
 278         }
 279         kref_init(&dev->kref);
 280         sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
 281         mutex_init(&dev->io_mutex);
 282
 283         dev->udev = usb_get_dev(interface_to_usbdev(interface));
 284         dev->interface = interface;
 285
 286         /* set up the endpoint information */
 287         /* use only the first bulk-in and bulk-out endpoints */
 288         iface_desc = interface->cur_altsetting;
 289         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 290                 endpoint = &iface_desc->endpoint[i].desc;
 291
 292                 if (!dev->bulk_in_endpointAddr &&
 293                     ((endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK)
 294                                         == USB_DIR_IN) &&
 295                     ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
 296                                         == USB_ENDPOINT_XFER_BULK)) {
 297                         /* we found a bulk in endpoint */
 298                         buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
 299                         dev->bulk_in_size = buffer_size;
 300                         dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
 301                         dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
 302                         if (!dev->bulk_in_buffer) {
 303                                 err("Could not allocate bulk_in_buffer");
 304                                 goto error;
 305                         }
 306                 }
 307
 308                 if (!dev->bulk_out_endpointAddr &&
 309                     ((endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK)
 310                                         == USB_DIR_OUT) &&
 311                     ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
 312                                         == USB_ENDPOINT_XFER_BULK)) {
 313                         /* we found a bulk out endpoint */
 314                         dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
 315                 }
 316         }
 317         if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
 318                 err("Could not find both bulk-in and bulk-out endpoints");
 319                 goto error;
 320         }
 321
 322         /* save our data pointer in this interface device */
 323         usb_set_intfdata(interface, dev);
 324
 325         /* we can register the device now, as it is ready */
 326         retval = usb_register_dev(interface, &skel_class);
 327         if (retval) {
 328                 /* something prevented us from registering this driver */
 329                 err("Not able to get a minor for this device.");
 330                 usb_set_intfdata(interface, NULL);
 331                 goto error;
 332         }
 333
 334         /* let the user know what node this device is now attached to */
 335         info("USB Skeleton device now attached to USBSkel-%d", interface->minor);
 336         return 0;
 337
 338 error:
 339         if (dev)
 340                 kref_put(&dev->kref, skel_delete);
 341         return retval;
 342 }
 343
 344 static void skel_disconnect(struct usb_interface *interface)
 345 {
 346         struct usb_skel *dev;
 347         int minor = interface->minor;
 348
 349         /* prevent skel_open() from racing skel_disconnect() */
 350         lock_kernel();
 351
 352         dev = usb_get_intfdata(interface);
 353         usb_set_intfdata(interface, NULL);
 354
 355         /* give back our minor */
 356         usb_deregister_dev(interface, &skel_class);
 357
 358         /* prevent more I/O from starting */
 359         mutex_lock(&dev->io_mutex);
 360         dev->interface = NULL;
 361         mutex_unlock(&dev->io_mutex);
 362
 363         unlock_kernel();
 364
 365         /* decrement our usage count */
 366         kref_put(&dev->kref, skel_delete);
 367
 368         info("USB Skeleton #%d now disconnected", minor);
 369 }
 370
 371 static struct usb_driver skel_driver = {
 372         .name =         "skeleton",
 373         .probe =        skel_probe,
 374         .disconnect =   skel_disconnect,
 375         .id_table =     skel_table,
 376 };
 377
 378 static int __init usb_skel_init(void)
 379 {
 380         int result;
 381
 382         /* register this driver with the USB subsystem */
 383         result = usb_register(&skel_driver);
 384         if (result)
 385                 err("usb_register failed. Error number %d", result);
 386
 387         return result;
 388 }
 389
 390 static void __exit usb_skel_exit(void)
 391 {
 392         /* deregister this driver with the USB subsystem */
 393         usb_deregister(&skel_driver);
 394 }
 395
 396 module_init (usb_skel_init);
 397 module_exit (usb_skel_exit);
 398
 399 MODULE_LICENSE("GPL");