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/config.h>
  17 #include <linux/kernel.h>
  18 #include <linux/errno.h>
  19 #include <linux/init.h>
  20 #include <linux/slab.h>
  21 #include <linux/module.h>
  22 #include <linux/kref.h>
  23 #include <asm/uaccess.h>
  24 #include <linux/usb.h>
  25
  26
  27 /* Define these values to match your devices */
  28 #define USB_SKEL_VENDOR_ID      0xfff0
  29 #define USB_SKEL_PRODUCT_ID     0xfff0
  30
  31 /* table of devices that work with this driver */
  32 static struct usb_device_id skel_table [] = {
  33         { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
  34         { }                                     /* Terminating entry */
  35 };
  36 MODULE_DEVICE_TABLE (usb, skel_table);
  37
  38
  39 /* Get a minor range for your devices from the usb maintainer */
  40 #define USB_SKEL_MINOR_BASE     192
  41
  42 /* Structure to hold all of our device specific stuff */
  43 struct usb_skel {
  44         struct usb_device *     udev;                   /* the usb device for this device */
  45         struct usb_interface *  interface;              /* the interface for this device */
  46         unsigned char *         bulk_in_buffer;         /* the buffer to receive data */
  47         size_t                  bulk_in_size;           /* the size of the receive buffer */
  48         __u8                    bulk_in_endpointAddr;   /* the address of the bulk in endpoint */
  49         __u8                    bulk_out_endpointAddr;  /* the address of the bulk out endpoint */
  50         struct kref             kref;
  51 };
  52 #define to_skel_dev(d) container_of(d, struct usb_skel, kref)
  53
  54 static struct usb_driver skel_driver;
  55
  56 static void skel_delete(struct kref *kref)
  57 {
  58         struct usb_skel *dev = to_skel_dev(kref);
  59
  60         usb_put_dev(dev->udev);
  61         kfree (dev->bulk_in_buffer);
  62         kfree (dev);
  63 }
  64
  65 static int skel_open(struct inode *inode, struct file *file)
  66 {
  67         struct usb_skel *dev;
  68         struct usb_interface *interface;
  69         int subminor;
  70         int retval = 0;
  71
  72         subminor = iminor(inode);
  73
  74         interface = usb_find_interface(&skel_driver, subminor);
  75         if (!interface) {
  76                 err ("%s - error, can't find device for minor %d",
  77                      __FUNCTION__, subminor);
  78                 retval = -ENODEV;
  79                 goto exit;
  80         }
  81
  82         dev = usb_get_intfdata(interface);
  83         if (!dev) {
  84                 retval = -ENODEV;
  85                 goto exit;
  86         }
  87
  88         /* increment our usage count for the device */
  89         kref_get(&dev->kref);
  90
  91         /* save our object in the file's private structure */
  92         file->private_data = dev;
  93
  94 exit:
  95         return retval;
  96 }
  97
  98 static int skel_release(struct inode *inode, struct file *file)
  99 {
 100         struct usb_skel *dev;
 101
 102         dev = (struct usb_skel *)file->private_data;
 103         if (dev == NULL)
 104                 return -ENODEV;
 105
 106         /* decrement the count on our device */
 107         kref_put(&dev->kref, skel_delete);
 108         return 0;
 109 }
 110
 111 static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos)
 112 {
 113         struct usb_skel *dev;
 114         int retval = 0;
 115         int bytes_read;
 116
 117         dev = (struct usb_skel *)file->private_data;
 118
 119         /* do a blocking bulk read to get data from the device */
 120         retval = usb_bulk_msg(dev->udev,
 121                               usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
 122                               dev->bulk_in_buffer,
 123                               min(dev->bulk_in_size, count),
 124                               &bytes_read, 10000);
 125
 126         /* if the read was successful, copy the data to userspace */
 127         if (!retval) {
 128                 if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
 129                         retval = -EFAULT;
 130                 else
 131                         retval = bytes_read;
 132         }
 133
 134         return retval;
 135 }
 136
 137 static void skel_write_bulk_callback(struct urb *urb, struct pt_regs *regs)
 138 {
 139         struct usb_skel *dev;
 140
 141         dev = (struct usb_skel *)urb->context;
 142
 143         /* sync/async unlink faults aren't errors */
 144         if (urb->status &&
 145             !(urb->status == -ENOENT ||
 146               urb->status == -ECONNRESET ||
 147               urb->status == -ESHUTDOWN)) {
 148                 dbg("%s - nonzero write bulk status received: %d",
 149                     __FUNCTION__, urb->status);
 150         }
 151
 152         /* free up our allocated buffer */
 153         usb_buffer_free(urb->dev, urb->transfer_buffer_length,
 154                         urb->transfer_buffer, urb->transfer_dma);
 155 }
 156
 157 static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos)
 158 {
 159         struct usb_skel *dev;
 160         int retval = 0;
 161         struct urb *urb = NULL;
 162         char *buf = NULL;
 163
 164         dev = (struct usb_skel *)file->private_data;
 165
 166         /* verify that we actually have some data to write */
 167         if (count == 0)
 168                 goto exit;
 169
 170         /* create a urb, and a buffer for it, and copy the data to the urb */
 171         urb = usb_alloc_urb(0, GFP_KERNEL);
 172         if (!urb) {
 173                 retval = -ENOMEM;
 174                 goto error;
 175         }
 176
 177         buf = usb_buffer_alloc(dev->udev, count, GFP_KERNEL, &urb->transfer_dma);
 178         if (!buf) {
 179                 retval = -ENOMEM;
 180                 goto error;
 181         }
 182
 183         if (copy_from_user(buf, user_buffer, count)) {
 184                 retval = -EFAULT;
 185                 goto error;
 186         }
 187
 188         /* initialize the urb properly */
 189         usb_fill_bulk_urb(urb, dev->udev,
 190                           usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
 191                           buf, count, skel_write_bulk_callback, dev);
 192         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 193
 194         /* send the data out the bulk port */
 195         retval = usb_submit_urb(urb, GFP_KERNEL);
 196         if (retval) {
 197                 err("%s - failed submitting write urb, error %d", __FUNCTION__, retval);
 198                 goto error;
 199         }
 200
 201         /* release our reference to this urb, the USB core will eventually free it entirely */
 202         usb_free_urb(urb);
 203
 204 exit:
 205         return count;
 206
 207 error:
 208         usb_buffer_free(dev->udev, count, buf, urb->transfer_dma);
 209         usb_free_urb(urb);
 210         return retval;
 211 }
 212
 213 static struct file_operations skel_fops = {
 214         .owner =        THIS_MODULE,
 215         .read =         skel_read,
 216         .write =        skel_write,
 217         .open =         skel_open,
 218         .release =      skel_release,
 219 };
 220
 221 /*
 222  * usb class driver info in order to get a minor number from the usb core,
 223  * and to have the device registered with devfs and the driver core
 224  */
 225 static struct usb_class_driver skel_class = {
 226         .name =         "usb/skel%d",
 227         .fops =         &skel_fops,
 228         .mode =         S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH,
 229         .minor_base =   USB_SKEL_MINOR_BASE,
 230 };
 231
 232 static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id)
 233 {
 234         struct usb_skel *dev = NULL;
 235         struct usb_host_interface *iface_desc;
 236         struct usb_endpoint_descriptor *endpoint;
 237         size_t buffer_size;
 238         int i;
 239         int retval = -ENOMEM;
 240
 241         /* allocate memory for our device state and initialize it */
 242         dev = kmalloc(sizeof(*dev), GFP_KERNEL);
 243         if (dev == NULL) {
 244                 err("Out of memory");
 245                 goto error;
 246         }
 247         memset(dev, 0x00, sizeof(*dev));
 248         kref_init(&dev->kref);
 249
 250         dev->udev = usb_get_dev(interface_to_usbdev(interface));
 251         dev->interface = interface;
 252
 253         /* set up the endpoint information */
 254         /* use only the first bulk-in and bulk-out endpoints */
 255         iface_desc = interface->cur_altsetting;
 256         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 257                 endpoint = &iface_desc->endpoint[i].desc;
 258
 259                 if (!dev->bulk_in_endpointAddr &&
 260                     (endpoint->bEndpointAddress & USB_DIR_IN) &&
 261                     ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
 262                                         == USB_ENDPOINT_XFER_BULK)) {
 263                         /* we found a bulk in endpoint */
 264                         buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
 265                         dev->bulk_in_size = buffer_size;
 266                         dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
 267                         dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
 268                         if (!dev->bulk_in_buffer) {
 269                                 err("Could not allocate bulk_in_buffer");
 270                                 goto error;
 271                         }
 272                 }
 273
 274                 if (!dev->bulk_out_endpointAddr &&
 275                     !(endpoint->bEndpointAddress & USB_DIR_OUT) &&
 276                     ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
 277                                         == USB_ENDPOINT_XFER_BULK)) {
 278                         /* we found a bulk out endpoint */
 279                         dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
 280                 }
 281         }
 282         if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
 283                 err("Could not find both bulk-in and bulk-out endpoints");
 284                 goto error;
 285         }
 286
 287         /* save our data pointer in this interface device */
 288         usb_set_intfdata(interface, dev);
 289
 290         /* we can register the device now, as it is ready */
 291         retval = usb_register_dev(interface, &skel_class);
 292         if (retval) {
 293                 /* something prevented us from registering this driver */
 294                 err("Not able to get a minor for this device.");
 295                 usb_set_intfdata(interface, NULL);
 296                 goto error;
 297         }
 298
 299         /* let the user know what node this device is now attached to */
 300         info("USB Skeleton device now attached to USBSkel-%d", interface->minor);
 301         return 0;
 302
 303 error:
 304         if (dev)
 305                 kref_put(&dev->kref, skel_delete);
 306         return retval;
 307 }
 308
 309 static void skel_disconnect(struct usb_interface *interface)
 310 {
 311         struct usb_skel *dev;
 312         int minor = interface->minor;
 313
 314         /* prevent skel_open() from racing skel_disconnect() */
 315         lock_kernel();
 316
 317         dev = usb_get_intfdata(interface);
 318         usb_set_intfdata(interface, NULL);
 319
 320         /* give back our minor */
 321         usb_deregister_dev(interface, &skel_class);
 322
 323         unlock_kernel();
 324
 325         /* decrement our usage count */
 326         kref_put(&dev->kref, skel_delete);
 327
 328         info("USB Skeleton #%d now disconnected", minor);
 329 }
 330
 331 static struct usb_driver skel_driver = {
 332         .owner =        THIS_MODULE,
 333         .name =         "skeleton",
 334         .probe =        skel_probe,
 335         .disconnect =   skel_disconnect,
 336         .id_table =     skel_table,
 337 };
 338
 339 static int __init usb_skel_init(void)
 340 {
 341         int result;
 342
 343         /* register this driver with the USB subsystem */
 344         result = usb_register(&skel_driver);
 345         if (result)
 346                 err("usb_register failed. Error number %d", result);
 347
 348         return result;
 349 }
 350
 351 static void __exit usb_skel_exit(void)
 352 {
 353         /* deregister this driver with the USB subsystem */
 354         usb_deregister(&skel_driver);
 355 }
 356
 357 module_init (usb_skel_init);
 358 module_exit (usb_skel_exit);
 359
 360 MODULE_LICENSE("GPL");