drivers/usb/usb-skeleton.c

   1 /*
   2  * USB Skeleton driver - 2.0
   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 easy to read and use, as no locks are now
  12  * needed anymore.
  13  *
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/errno.h>
  18 #include <linux/init.h>
  19 #include <linux/slab.h>
  20 #include <linux/module.h>
  21 #include <linux/kref.h>
  22 #include <asm/uaccess.h>
  23 #include <linux/usb.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 };
  56 #define to_skel_dev(d) container_of(d, struct usb_skel, kref)
  57
  58 static struct usb_driver skel_driver;
  59
  60 static void skel_delete(struct kref *kref)
  61 {
  62         struct usb_skel *dev = to_skel_dev(kref);
  63
  64         usb_put_dev(dev->udev);
  65         kfree (dev->bulk_in_buffer);
  66         kfree (dev);
  67 }
  68
  69 static int skel_open(struct inode *inode, struct file *file)
  70 {
  71         struct usb_skel *dev;
  72         struct usb_interface *interface;
  73         int subminor;
  74         int retval = 0;
  75
  76         subminor = iminor(inode);
  77
  78         interface = usb_find_interface(&skel_driver, subminor);
  79         if (!interface) {
  80                 err ("%s - error, can't find device for minor %d",
  81                      __FUNCTION__, subminor);
  82                 retval = -ENODEV;
  83                 goto exit;
  84         }
  85
  86         dev = usb_get_intfdata(interface);
  87         if (!dev) {
  88                 retval = -ENODEV;
  89                 goto exit;
  90         }
  91
  92         /* increment our usage count for the device */
  93         kref_get(&dev->kref);
  94
  95         /* save our object in the file's private structure */
  96         file->private_data = dev;
  97
  98 exit:
  99         return retval;
 100 }
 101
 102 static int skel_release(struct inode *inode, struct file *file)
 103 {
 104         struct usb_skel *dev;
 105
 106         dev = (struct usb_skel *)file->private_data;
 107         if (dev == NULL)
 108                 return -ENODEV;
 109
 110         /* decrement the count on our device */
 111         kref_put(&dev->kref, skel_delete);
 112         return 0;
 113 }
 114
 115 static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos)
 116 {
 117         struct usb_skel *dev;
 118         int retval = 0;
 119         int bytes_read;
 120
 121         dev = (struct usb_skel *)file->private_data;
 122
 123         /* do a blocking bulk read to get data from the device */
 124         retval = usb_bulk_msg(dev->udev,
 125                               usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
 126                               dev->bulk_in_buffer,
 127                               min(dev->bulk_in_size, count),
 128                               &bytes_read, 10000);
 129
 130         /* if the read was successful, copy the data to userspace */
 131         if (!retval) {
 132                 if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
 133                         retval = -EFAULT;
 134                 else
 135                         retval = bytes_read;
 136         }
 137
 138         return retval;
 139 }
 140
 141 static void skel_write_bulk_callback(struct urb *urb, struct pt_regs *regs)
 142 {
 143         struct usb_skel *dev;
 144
 145         dev = (struct usb_skel *)urb->context;
 146
 147         /* sync/async unlink faults aren't errors */
 148         if (urb->status &&
 149             !(urb->status == -ENOENT ||
 150               urb->status == -ECONNRESET ||
 151               urb->status == -ESHUTDOWN)) {
 152                 dbg("%s - nonzero write bulk status received: %d",
 153                     __FUNCTION__, urb->status);
 154         }
 155
 156         /* free up our allocated buffer */
 157         usb_buffer_free(urb->dev, urb->transfer_buffer_length,
 158                         urb->transfer_buffer, urb->transfer_dma);
 159         up(&dev->limit_sem);
 160 }
 161
 162 static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos)
 163 {
 164         struct usb_skel *dev;
 165         int retval = 0;
 166         struct urb *urb = NULL;
 167         char *buf = NULL;
 168         size_t writesize = min(count, (size_t)MAX_TRANSFER);
 169
 170         dev = (struct usb_skel *)file->private_data;
 171
 172         /* verify that we actually have some data to write */
 173         if (count == 0)
 174                 goto exit;
 175
 176         /* limit the number of URBs in flight to stop a user from using up all RAM */
 177         if (down_interruptible(&dev->limit_sem)) {
 178                 retval = -ERESTARTSYS;
 179                 goto exit;
 180         }
 181
 182         /* create a urb, and a buffer for it, and copy the data to the urb */
 183         urb = usb_alloc_urb(0, GFP_KERNEL);
 184         if (!urb) {
 185                 retval = -ENOMEM;
 186                 goto error;
 187         }
 188
 189         buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma);
 190         if (!buf) {
 191                 retval = -ENOMEM;
 192                 goto error;
 193         }
 194
 195         if (copy_from_user(buf, user_buffer, writesize)) {
 196                 retval = -EFAULT;
 197                 goto error;
 198         }
 199
 200         /* initialize the urb properly */
 201         usb_fill_bulk_urb(urb, dev->udev,
 202                           usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
 203                           buf, writesize, skel_write_bulk_callback, dev);
 204         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 205
 206         /* send the data out the bulk port */
 207         retval = usb_submit_urb(urb, GFP_KERNEL);
 208         if (retval) {
 209                 err("%s - failed submitting write urb, error %d", __FUNCTION__, retval);
 210                 goto error;
 211         }
 212
 213         /* release our reference to this urb, the USB core will eventually free it entirely */
 214         usb_free_urb(urb);
 215
 216 exit:
 217         return writesize;
 218
 219 error:
 220         usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
 221         usb_free_urb(urb);
 222         up(&dev->limit_sem);
 223         return retval;
 224 }
 225
 226 static struct file_operations skel_fops = {
 227         .owner =        THIS_MODULE,
 228         .read =         skel_read,
 229         .write =        skel_write,
 230         .open =         skel_open,
 231         .release =      skel_release,
 232 };
 233
 234 /*
 235  * usb class driver info in order to get a minor number from the usb core,
 236  * and to have the device registered with the driver core
 237  */
 238 static struct usb_class_driver skel_class = {
 239         .name =         "skel%d",
 240         .fops =         &skel_fops,
 241         .minor_base =   USB_SKEL_MINOR_BASE,
 242 };
 243
 244 static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id)
 245 {
 246         struct usb_skel *dev = NULL;
 247         struct usb_host_interface *iface_desc;
 248         struct usb_endpoint_descriptor *endpoint;
 249         size_t buffer_size;
 250         int i;
 251         int retval = -ENOMEM;
 252
 253         /* allocate memory for our device state and initialize it */
 254         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 255         if (dev == NULL) {
 256                 err("Out of memory");
 257                 goto error;
 258         }
 259         kref_init(&dev->kref);
 260         sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
 261
 262         dev->udev = usb_get_dev(interface_to_usbdev(interface));
 263         dev->interface = interface;
 264
 265         /* set up the endpoint information */
 266         /* use only the first bulk-in and bulk-out endpoints */
 267         iface_desc = interface->cur_altsetting;
 268         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 269                 endpoint = &iface_desc->endpoint[i].desc;
 270
 271                 if (!dev->bulk_in_endpointAddr &&
 272                     ((endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK)
 273                                         == USB_DIR_IN) &&
 274                     ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
 275                                         == USB_ENDPOINT_XFER_BULK)) {
 276                         /* we found a bulk in endpoint */
 277                         buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
 278                         dev->bulk_in_size = buffer_size;
 279                         dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
 280                         dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
 281                         if (!dev->bulk_in_buffer) {
 282                                 err("Could not allocate bulk_in_buffer");
 283                                 goto error;
 284                         }
 285                 }
 286
 287                 if (!dev->bulk_out_endpointAddr &&
 288                     ((endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK)
 289                                         == USB_DIR_OUT) &&
 290                     ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
 291                                         == USB_ENDPOINT_XFER_BULK)) {
 292                         /* we found a bulk out endpoint */
 293                         dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
 294                 }
 295         }
 296         if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
 297                 err("Could not find both bulk-in and bulk-out endpoints");
 298                 goto error;
 299         }
 300
 301         /* save our data pointer in this interface device */
 302         usb_set_intfdata(interface, dev);
 303
 304         /* we can register the device now, as it is ready */
 305         retval = usb_register_dev(interface, &skel_class);
 306         if (retval) {
 307                 /* something prevented us from registering this driver */
 308                 err("Not able to get a minor for this device.");
 309                 usb_set_intfdata(interface, NULL);
 310                 goto error;
 311         }
 312
 313         /* let the user know what node this device is now attached to */
 314         info("USB Skeleton device now attached to USBSkel-%d", interface->minor);
 315         return 0;
 316
 317 error:
 318         if (dev)
 319                 kref_put(&dev->kref, skel_delete);
 320         return retval;
 321 }
 322
 323 static void skel_disconnect(struct usb_interface *interface)
 324 {
 325         struct usb_skel *dev;
 326         int minor = interface->minor;
 327
 328         /* prevent skel_open() from racing skel_disconnect() */
 329         lock_kernel();
 330
 331         dev = usb_get_intfdata(interface);
 332         usb_set_intfdata(interface, NULL);
 333
 334         /* give back our minor */
 335         usb_deregister_dev(interface, &skel_class);
 336
 337         unlock_kernel();
 338
 339         /* decrement our usage count */
 340         kref_put(&dev->kref, skel_delete);
 341
 342         info("USB Skeleton #%d now disconnected", minor);
 343 }
 344
 345 static struct usb_driver skel_driver = {
 346         .name =         "skeleton",
 347         .probe =        skel_probe,
 348         .disconnect =   skel_disconnect,
 349         .id_table =     skel_table,
 350 };
 351
 352 static int __init usb_skel_init(void)
 353 {
 354         int result;
 355
 356         /* register this driver with the USB subsystem */
 357         result = usb_register(&skel_driver);
 358         if (result)
 359                 err("usb_register failed. Error number %d", result);
 360
 361         return result;
 362 }
 363
 364 static void __exit usb_skel_exit(void)
 365 {
 366         /* deregister this driver with the USB subsystem */
 367         usb_deregister(&skel_driver);
 368 }
 369
 370 module_init (usb_skel_init);
 371 module_exit (usb_skel_exit);
 372
 373 MODULE_LICENSE("GPL");