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 /* to prevent a race between open and disconnect */ 38 static DEFINE_MUTEX(skel_open_lock); 39 40 41 /* Get a minor range for your devices from the usb maintainer */ 42 #define USB_SKEL_MINOR_BASE 192 43 44 /* our private defines. if this grows any larger, use your own .h file */ 45 #define MAX_TRANSFER (PAGE_SIZE - 512) 46 /* MAX_TRANSFER is chosen so that the VM is not stressed by 47 allocations > PAGE_SIZE and the number of packets in a page 48 is an integer 512 is the largest possible packet on EHCI */ 49 #define WRITES_IN_FLIGHT 8 50 /* arbitrarily chosen */ 51 52 /* Structure to hold all of our device specific stuff */ 53 struct usb_skel { 54 struct usb_device *udev; /* the usb device for this device */ 55 struct usb_interface *interface; /* the interface for this device */ 56 struct semaphore limit_sem; /* limiting the number of writes in progress */ 57 unsigned char *bulk_in_buffer; /* the buffer to receive data */ 58 size_t bulk_in_size; /* the size of the receive buffer */ 59 __u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */ 60 __u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */ 61 struct kref kref; 62 struct mutex io_mutex; /* synchronize I/O with disconnect */ 63 }; 64 #define to_skel_dev(d) container_of(d, struct usb_skel, kref) 65 66 static struct usb_driver skel_driver; 67 68 static void skel_delete(struct kref *kref) 69 { 70 struct usb_skel *dev = to_skel_dev(kref); 71 72 usb_put_dev(dev->udev); 73 kfree(dev->bulk_in_buffer); 74 kfree(dev); 75 } 76 77 static int skel_open(struct inode *inode, struct file *file) 78 { 79 struct usb_skel *dev; 80 struct usb_interface *interface; 81 int subminor; 82 int retval = 0; 83 84 subminor = iminor(inode); 85 86 mutex_lock(&skel_open_lock); 87 interface = usb_find_interface(&skel_driver, subminor); 88 if (!interface) { 89 mutex_unlock(&skel_open_lock); 90 err ("%s - error, can't find device for minor %d", 91 __FUNCTION__, subminor); 92 retval = -ENODEV; 93 goto exit; 94 } 95 96 dev = usb_get_intfdata(interface); 97 if (!dev) { 98 mutex_unlock(&skel_open_lock); 99 retval = -ENODEV; 100 goto exit; 101 } 102 103 /* increment our usage count for the device */ 104 kref_get(&dev->kref); 105 /* now we can drop the lock */ 106 mutex_unlock(&skel_open_lock); 107 108 /* prevent the device from being autosuspended */ 109 retval = usb_autopm_get_interface(interface); 110 if (retval) { 111 kref_put(&dev->kref, skel_delete); 112 goto exit; 113 } 114 115 /* save our object in the file's private structure */ 116 file->private_data = dev; 117 118 exit: 119 return retval; 120 } 121 122 static int skel_release(struct inode *inode, struct file *file) 123 { 124 struct usb_skel *dev; 125 126 dev = (struct usb_skel *)file->private_data; 127 if (dev == NULL) 128 return -ENODEV; 129 130 /* allow the device to be autosuspended */ 131 mutex_lock(&dev->io_mutex); 132 if (dev->interface) 133 usb_autopm_put_interface(dev->interface); 134 mutex_unlock(&dev->io_mutex); 135 136 /* decrement the count on our device */ 137 kref_put(&dev->kref, skel_delete); 138 return 0; 139 } 140 141 static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos) 142 { 143 struct usb_skel *dev; 144 int retval; 145 int bytes_read; 146 147 dev = (struct usb_skel *)file->private_data; 148 149 mutex_lock(&dev->io_mutex); 150 if (!dev->interface) { /* disconnect() was called */ 151 retval = -ENODEV; 152 goto exit; 153 } 154 155 /* do a blocking bulk read to get data from the device */ 156 retval = usb_bulk_msg(dev->udev, 157 usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr), 158 dev->bulk_in_buffer, 159 min(dev->bulk_in_size, count), 160 &bytes_read, 10000); 161 162 /* if the read was successful, copy the data to userspace */ 163 if (!retval) { 164 if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read)) 165 retval = -EFAULT; 166 else 167 retval = bytes_read; 168 } 169 170 exit: 171 mutex_unlock(&dev->io_mutex); 172 return retval; 173 } 174 175 static void skel_write_bulk_callback(struct urb *urb) 176 { 177 struct usb_skel *dev; 178 179 dev = (struct usb_skel *)urb->context; 180 181 /* sync/async unlink faults aren't errors */ 182 if (urb->status && 183 !(urb->status == -ENOENT || 184 urb->status == -ECONNRESET || 185 urb->status == -ESHUTDOWN)) { 186 err("%s - nonzero write bulk status received: %d", 187 __FUNCTION__, urb->status); 188 } 189 190 /* free up our allocated buffer */ 191 usb_buffer_free(urb->dev, urb->transfer_buffer_length, 192 urb->transfer_buffer, urb->transfer_dma); 193 up(&dev->limit_sem); 194 } 195 196 static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos) 197 { 198 struct usb_skel *dev; 199 int retval = 0; 200 struct urb *urb = NULL; 201 char *buf = NULL; 202 size_t writesize = min(count, (size_t)MAX_TRANSFER); 203 204 dev = (struct usb_skel *)file->private_data; 205 206 /* verify that we actually have some data to write */ 207 if (count == 0) 208 goto exit; 209 210 /* limit the number of URBs in flight to stop a user from using up all RAM */ 211 if (down_interruptible(&dev->limit_sem)) { 212 retval = -ERESTARTSYS; 213 goto exit; 214 } 215 216 /* create a urb, and a buffer for it, and copy the data to the urb */ 217 urb = usb_alloc_urb(0, GFP_KERNEL); 218 if (!urb) { 219 retval = -ENOMEM; 220 goto error; 221 } 222 223 buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma); 224 if (!buf) { 225 retval = -ENOMEM; 226 goto error; 227 } 228 229 if (copy_from_user(buf, user_buffer, writesize)) { 230 retval = -EFAULT; 231 goto error; 232 } 233 234 /* this lock makes sure we don't submit URBs to gone devices */ 235 mutex_lock(&dev->io_mutex); 236 if (!dev->interface) { /* disconnect() was called */ 237 mutex_unlock(&dev->io_mutex); 238 retval = -ENODEV; 239 goto error; 240 } 241 242 /* initialize the urb properly */ 243 usb_fill_bulk_urb(urb, dev->udev, 244 usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr), 245 buf, writesize, skel_write_bulk_callback, dev); 246 urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP; 247 248 /* send the data out the bulk port */ 249 retval = usb_submit_urb(urb, GFP_KERNEL); 250 mutex_unlock(&dev->io_mutex); 251 if (retval) { 252 err("%s - failed submitting write urb, error %d", __FUNCTION__, retval); 253 goto error; 254 } 255 256 /* release our reference to this urb, the USB core will eventually free it entirely */ 257 usb_free_urb(urb); 258 259 260 return writesize; 261 262 error: 263 if (urb) { 264 usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma); 265 usb_free_urb(urb); 266 } 267 up(&dev->limit_sem); 268 269 exit: 270 return retval; 271 } 272 273 static const struct file_operations skel_fops = { 274 .owner = THIS_MODULE, 275 .read = skel_read, 276 .write = skel_write, 277 .open = skel_open, 278 .release = skel_release, 279 }; 280 281 /* 282 * usb class driver info in order to get a minor number from the usb core, 283 * and to have the device registered with the driver core 284 */ 285 static struct usb_class_driver skel_class = { 286 .name = "skel%d", 287 .fops = &skel_fops, 288 .minor_base = USB_SKEL_MINOR_BASE, 289 }; 290 291 static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id) 292 { 293 struct usb_skel *dev; 294 struct usb_host_interface *iface_desc; 295 struct usb_endpoint_descriptor *endpoint; 296 size_t buffer_size; 297 int i; 298 int retval = -ENOMEM; 299 300 /* allocate memory for our device state and initialize it */ 301 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 302 if (!dev) { 303 err("Out of memory"); 304 goto error; 305 } 306 kref_init(&dev->kref); 307 sema_init(&dev->limit_sem, WRITES_IN_FLIGHT); 308 mutex_init(&dev->io_mutex); 309 310 dev->udev = usb_get_dev(interface_to_usbdev(interface)); 311 dev->interface = interface; 312 313 /* set up the endpoint information */ 314 /* use only the first bulk-in and bulk-out endpoints */ 315 iface_desc = interface->cur_altsetting; 316 for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) { 317 endpoint = &iface_desc->endpoint[i].desc; 318 319 if (!dev->bulk_in_endpointAddr && 320 usb_endpoint_is_bulk_in(endpoint)) { 321 /* we found a bulk in endpoint */ 322 buffer_size = le16_to_cpu(endpoint->wMaxPacketSize); 323 dev->bulk_in_size = buffer_size; 324 dev->bulk_in_endpointAddr = endpoint->bEndpointAddress; 325 dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL); 326 if (!dev->bulk_in_buffer) { 327 err("Could not allocate bulk_in_buffer"); 328 goto error; 329 } 330 } 331 332 if (!dev->bulk_out_endpointAddr && 333 usb_endpoint_is_bulk_out(endpoint)) { 334 /* we found a bulk out endpoint */ 335 dev->bulk_out_endpointAddr = endpoint->bEndpointAddress; 336 } 337 } 338 if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) { 339 err("Could not find both bulk-in and bulk-out endpoints"); 340 goto error; 341 } 342 343 /* save our data pointer in this interface device */ 344 usb_set_intfdata(interface, dev); 345 346 /* we can register the device now, as it is ready */ 347 retval = usb_register_dev(interface, &skel_class); 348 if (retval) { 349 /* something prevented us from registering this driver */ 350 err("Not able to get a minor for this device."); 351 usb_set_intfdata(interface, NULL); 352 goto error; 353 } 354 355 /* let the user know what node this device is now attached to */ 356 info("USB Skeleton device now attached to USBSkel-%d", interface->minor); 357 return 0; 358 359 error: 360 if (dev) 361 /* this frees allocated memory */ 362 kref_put(&dev->kref, skel_delete); 363 return retval; 364 } 365 366 static void skel_disconnect(struct usb_interface *interface) 367 { 368 struct usb_skel *dev; 369 int minor = interface->minor; 370 371 /* prevent skel_open() from racing skel_disconnect() */ 372 mutex_lock(&skel_open_lock); 373 374 dev = usb_get_intfdata(interface); 375 usb_set_intfdata(interface, NULL); 376 377 /* give back our minor */ 378 usb_deregister_dev(interface, &skel_class); 379 mutex_unlock(&skel_open_lock); 380 381 /* prevent more I/O from starting */ 382 mutex_lock(&dev->io_mutex); 383 dev->interface = NULL; 384 mutex_unlock(&dev->io_mutex); 385 386 387 388 /* decrement our usage count */ 389 kref_put(&dev->kref, skel_delete); 390 391 info("USB Skeleton #%d now disconnected", minor); 392 } 393 394 static struct usb_driver skel_driver = { 395 .name = "skeleton", 396 .probe = skel_probe, 397 .disconnect = skel_disconnect, 398 .id_table = skel_table, 399 .supports_autosuspend = 1, 400 }; 401 402 static int __init usb_skel_init(void) 403 { 404 int result; 405 406 /* register this driver with the USB subsystem */ 407 result = usb_register(&skel_driver); 408 if (result) 409 err("usb_register failed. Error number %d", result); 410 411 return result; 412 } 413 414 static void __exit usb_skel_exit(void) 415 { 416 /* deregister this driver with the USB subsystem */ 417 usb_deregister(&skel_driver); 418 } 419 420 module_init(usb_skel_init); 421 module_exit(usb_skel_exit); 422 423 MODULE_LICENSE("GPL"); 424