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 /* our private defines. if this grows any larger, use your own .h file */
  43 #define MAX_TRANSFER            ( PAGE_SIZE - 512 )
  44 #define WRITES_IN_FLIGHT        8
  45
  46 /* Structure to hold all of our device specific stuff */
  47 struct usb_skel {
  48         struct usb_device *     udev;                   /* the usb device for this device */
  49         struct usb_interface *  interface;              /* the interface for this device */
  50         struct semaphore        limit_sem;              /* limiting the number of writes in progress */
  51         unsigned char *         bulk_in_buffer;         /* the buffer to receive data */
  52         size_t                  bulk_in_size;           /* the size of the receive buffer */
  53         __u8                    bulk_in_endpointAddr;   /* the address of the bulk in endpoint */
  54         __u8                    bulk_out_endpointAddr;  /* the address of the bulk out endpoint */
  55         struct kref             kref;
  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         /* do a blocking bulk read to get data from the device */
 125         retval = usb_bulk_msg(dev->udev,
 126                               usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
 127                               dev->bulk_in_buffer,
 128                               min(dev->bulk_in_size, count),
 129                               &bytes_read, 10000);
 130
 131         /* if the read was successful, copy the data to userspace */
 132         if (!retval) {
 133                 if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
 134                         retval = -EFAULT;
 135                 else
 136                         retval = bytes_read;
 137         }
 138
 139         return retval;
 140 }
 141
 142 static void skel_write_bulk_callback(struct urb *urb, struct pt_regs *regs)
 143 {
 144         struct usb_skel *dev;
 145
 146         dev = (struct usb_skel *)urb->context;
 147
 148         /* sync/async unlink faults aren't errors */
 149         if (urb->status &&
 150             !(urb->status == -ENOENT ||
 151               urb->status == -ECONNRESET ||
 152               urb->status == -ESHUTDOWN)) {
 153                 dbg("%s - nonzero write bulk status received: %d",
 154                     __FUNCTION__, urb->status);
 155         }
 156
 157         /* free up our allocated buffer */
 158         usb_buffer_free(urb->dev, urb->transfer_buffer_length,
 159                         urb->transfer_buffer, urb->transfer_dma);
 160         up(&dev->limit_sem);
 161 }
 162
 163 static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos)
 164 {
 165         struct usb_skel *dev;
 166         int retval = 0;
 167         struct urb *urb = NULL;
 168         char *buf = NULL;
 169         size_t writesize = min(count, (size_t)MAX_TRANSFER);
 170
 171         dev = (struct usb_skel *)file->private_data;
 172
 173         /* verify that we actually have some data to write */
 174         if (count == 0)
 175                 goto exit;
 176
 177         /* limit the number of URBs in flight to stop a user from using up all RAM */
 178         if (down_interruptible(&dev->limit_sem)) {
 179                 retval = -ERESTARTSYS;
 180                 goto exit;
 181         }
 182
 183         /* create a urb, and a buffer for it, and copy the data to the urb */
 184         urb = usb_alloc_urb(0, GFP_KERNEL);
 185         if (!urb) {
 186                 retval = -ENOMEM;
 187                 goto error;
 188         }
 189
 190         buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma);
 191         if (!buf) {
 192                 retval = -ENOMEM;
 193                 goto error;
 194         }
 195
 196         if (copy_from_user(buf, user_buffer, writesize)) {
 197                 retval = -EFAULT;
 198                 goto error;
 199         }
 200
 201         /* initialize the urb properly */
 202         usb_fill_bulk_urb(urb, dev->udev,
 203                           usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
 204                           buf, writesize, skel_write_bulk_callback, dev);
 205         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 206
 207         /* send the data out the bulk port */
 208         retval = usb_submit_urb(urb, GFP_KERNEL);
 209         if (retval) {
 210                 err("%s - failed submitting write urb, error %d", __FUNCTION__, retval);
 211                 goto error;
 212         }
 213
 214         /* release our reference to this urb, the USB core will eventually free it entirely */
 215         usb_free_urb(urb);
 216
 217 exit:
 218         return writesize;
 219
 220 error:
 221         usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
 222         usb_free_urb(urb);
 223         up(&dev->limit_sem);
 224         return retval;
 225 }
 226
 227 static struct file_operations skel_fops = {
 228         .owner =        THIS_MODULE,
 229         .read =         skel_read,
 230         .write =        skel_write,
 231         .open =         skel_open,
 232         .release =      skel_release,
 233 };
 234
 235 /*
 236  * usb class driver info in order to get a minor number from the usb core,
 237  * and to have the device registered with devfs and the driver core
 238  */
 239 static struct usb_class_driver skel_class = {
 240         .name =         "skel%d",
 241         .fops =         &skel_fops,
 242         .minor_base =   USB_SKEL_MINOR_BASE,
 243 };
 244
 245 static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id)
 246 {
 247         struct usb_skel *dev = NULL;
 248         struct usb_host_interface *iface_desc;
 249         struct usb_endpoint_descriptor *endpoint;
 250         size_t buffer_size;
 251         int i;
 252         int retval = -ENOMEM;
 253
 254         /* allocate memory for our device state and initialize it */
 255         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 256         if (dev == NULL) {
 257                 err("Out of memory");
 258                 goto error;
 259         }
 260         kref_init(&dev->kref);
 261         sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
 262
 263         dev->udev = usb_get_dev(interface_to_usbdev(interface));
 264         dev->interface = interface;
 265
 266         /* set up the endpoint information */
 267         /* use only the first bulk-in and bulk-out endpoints */
 268         iface_desc = interface->cur_altsetting;
 269         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 270                 endpoint = &iface_desc->endpoint[i].desc;
 271
 272                 if (!dev->bulk_in_endpointAddr &&
 273                     ((endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK)
 274                                         == USB_DIR_IN) &&
 275                     ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
 276                                         == USB_ENDPOINT_XFER_BULK)) {
 277                         /* we found a bulk in endpoint */
 278                         buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
 279                         dev->bulk_in_size = buffer_size;
 280                         dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
 281                         dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
 282                         if (!dev->bulk_in_buffer) {
 283                                 err("Could not allocate bulk_in_buffer");
 284                                 goto error;
 285                         }
 286                 }
 287
 288                 if (!dev->bulk_out_endpointAddr &&
 289                     ((endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK)
 290                                         == USB_DIR_OUT) &&
 291                     ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK)
 292                                         == USB_ENDPOINT_XFER_BULK)) {
 293                         /* we found a bulk out endpoint */
 294                         dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
 295                 }
 296         }
 297         if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
 298                 err("Could not find both bulk-in and bulk-out endpoints");
 299                 goto error;
 300         }
 301
 302         /* save our data pointer in this interface device */
 303         usb_set_intfdata(interface, dev);
 304
 305         /* we can register the device now, as it is ready */
 306         retval = usb_register_dev(interface, &skel_class);
 307         if (retval) {
 308                 /* something prevented us from registering this driver */
 309                 err("Not able to get a minor for this device.");
 310                 usb_set_intfdata(interface, NULL);
 311                 goto error;
 312         }
 313
 314         /* let the user know what node this device is now attached to */
 315         info("USB Skeleton device now attached to USBSkel-%d", interface->minor);
 316         return 0;
 317
 318 error:
 319         if (dev)
 320                 kref_put(&dev->kref, skel_delete);
 321         return retval;
 322 }
 323
 324 static void skel_disconnect(struct usb_interface *interface)
 325 {
 326         struct usb_skel *dev;
 327         int minor = interface->minor;
 328
 329         /* prevent skel_open() from racing skel_disconnect() */
 330         lock_kernel();
 331
 332         dev = usb_get_intfdata(interface);
 333         usb_set_intfdata(interface, NULL);
 334
 335         /* give back our minor */
 336         usb_deregister_dev(interface, &skel_class);
 337
 338         unlock_kernel();
 339
 340         /* decrement our usage count */
 341         kref_put(&dev->kref, skel_delete);
 342
 343         info("USB Skeleton #%d now disconnected", minor);
 344 }
 345
 346 static struct usb_driver skel_driver = {
 347         .name =         "skeleton",
 348         .probe =        skel_probe,
 349         .disconnect =   skel_disconnect,
 350         .id_table =     skel_table,
 351 };
 352
 353 static int __init usb_skel_init(void)
 354 {
 355         int result;
 356
 357         /* register this driver with the USB subsystem */
 358         result = usb_register(&skel_driver);
 359         if (result)
 360                 err("usb_register failed. Error number %d", result);
 361
 362         return result;
 363 }
 364
 365 static void __exit usb_skel_exit(void)
 366 {
 367         /* deregister this driver with the USB subsystem */
 368         usb_deregister(&skel_driver);
 369 }
 370
 371 module_init (usb_skel_init);
 372 module_exit (usb_skel_exit);
 373
 374 MODULE_LICENSE("GPL");