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