1 /* 2 * USB Skeleton driver - 2.1 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 * 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 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 /* 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 mutex_lock(&dev->io_mutex); 125 if (!dev->interface) { /* disconnect() was called */ 126 retval = -ENODEV; 127 goto exit; 128 } 129 130 /* do a blocking bulk read to get data from the device */ 131 retval = usb_bulk_msg(dev->udev, 132 usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr), 133 dev->bulk_in_buffer, 134 min(dev->bulk_in_size, count), 135 &bytes_read, 10000); 136 137 /* if the read was successful, copy the data to userspace */ 138 if (!retval) { 139 if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read)) 140 retval = -EFAULT; 141 else 142 retval = bytes_read; 143 } 144 145 exit: 146 mutex_unlock(&dev->io_mutex); 147 return retval; 148 } 149 150 static void skel_write_bulk_callback(struct urb *urb, struct pt_regs *regs) 151 { 152 struct usb_skel *dev; 153 154 dev = (struct usb_skel *)urb->context; 155 156 /* sync/async unlink faults aren't errors */ 157 if (urb->status && 158 !(urb->status == -ENOENT || 159 urb->status == -ECONNRESET || 160 urb->status == -ESHUTDOWN)) { 161 dbg("%s - nonzero write bulk status received: %d", 162 __FUNCTION__, urb->status); 163 } 164 165 /* free up our allocated buffer */ 166 usb_buffer_free(urb->dev, urb->transfer_buffer_length, 167 urb->transfer_buffer, urb->transfer_dma); 168 up(&dev->limit_sem); 169 } 170 171 static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos) 172 { 173 struct usb_skel *dev; 174 int retval = 0; 175 struct urb *urb = NULL; 176 char *buf = NULL; 177 size_t writesize = min(count, (size_t)MAX_TRANSFER); 178 179 dev = (struct usb_skel *)file->private_data; 180 181 /* verify that we actually have some data to write */ 182 if (count == 0) 183 goto exit; 184 185 /* limit the number of URBs in flight to stop a user from using up all RAM */ 186 if (down_interruptible(&dev->limit_sem)) { 187 retval = -ERESTARTSYS; 188 goto exit; 189 } 190 191 mutex_lock(&dev->io_mutex); 192 if (!dev->interface) { /* disconnect() was called */ 193 retval = -ENODEV; 194 goto error; 195 } 196 197 /* create a urb, and a buffer for it, and copy the data to the urb */ 198 urb = usb_alloc_urb(0, GFP_KERNEL); 199 if (!urb) { 200 retval = -ENOMEM; 201 goto error; 202 } 203 204 buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma); 205 if (!buf) { 206 retval = -ENOMEM; 207 goto error; 208 } 209 210 if (copy_from_user(buf, user_buffer, writesize)) { 211 retval = -EFAULT; 212 goto error; 213 } 214 215 /* initialize the urb properly */ 216 usb_fill_bulk_urb(urb, dev->udev, 217 usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr), 218 buf, writesize, skel_write_bulk_callback, dev); 219 urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP; 220 221 /* send the data out the bulk port */ 222 retval = usb_submit_urb(urb, GFP_KERNEL); 223 if (retval) { 224 err("%s - failed submitting write urb, error %d", __FUNCTION__, retval); 225 goto error; 226 } 227 228 /* release our reference to this urb, the USB core will eventually free it entirely */ 229 usb_free_urb(urb); 230 231 mutex_unlock(&dev->io_mutex); 232 return writesize; 233 234 error: 235 if (urb) { 236 usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma); 237 usb_free_urb(urb); 238 } 239 mutex_unlock(&dev->io_mutex); 240 up(&dev->limit_sem); 241 242 exit: 243 return retval; 244 } 245 246 static const struct file_operations skel_fops = { 247 .owner = THIS_MODULE, 248 .read = skel_read, 249 .write = skel_write, 250 .open = skel_open, 251 .release = skel_release, 252 }; 253 254 /* 255 * usb class driver info in order to get a minor number from the usb core, 256 * and to have the device registered with the driver core 257 */ 258 static struct usb_class_driver skel_class = { 259 .name = "skel%d", 260 .fops = &skel_fops, 261 .minor_base = USB_SKEL_MINOR_BASE, 262 }; 263 264 static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id) 265 { 266 struct usb_skel *dev = NULL; 267 struct usb_host_interface *iface_desc; 268 struct usb_endpoint_descriptor *endpoint; 269 size_t buffer_size; 270 int i; 271 int retval = -ENOMEM; 272 273 /* allocate memory for our device state and initialize it */ 274 dev = kzalloc(sizeof(*dev), GFP_KERNEL); 275 if (dev == NULL) { 276 err("Out of memory"); 277 goto error; 278 } 279 kref_init(&dev->kref); 280 sema_init(&dev->limit_sem, WRITES_IN_FLIGHT); 281 mutex_init(&dev->io_mutex); 282 283 dev->udev = usb_get_dev(interface_to_usbdev(interface)); 284 dev->interface = interface; 285 286 /* set up the endpoint information */ 287 /* use only the first bulk-in and bulk-out endpoints */ 288 iface_desc = interface->cur_altsetting; 289 for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) { 290 endpoint = &iface_desc->endpoint[i].desc; 291 292 if (!dev->bulk_in_endpointAddr && 293 ((endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK) 294 == USB_DIR_IN) && 295 ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) 296 == USB_ENDPOINT_XFER_BULK)) { 297 /* we found a bulk in endpoint */ 298 buffer_size = le16_to_cpu(endpoint->wMaxPacketSize); 299 dev->bulk_in_size = buffer_size; 300 dev->bulk_in_endpointAddr = endpoint->bEndpointAddress; 301 dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL); 302 if (!dev->bulk_in_buffer) { 303 err("Could not allocate bulk_in_buffer"); 304 goto error; 305 } 306 } 307 308 if (!dev->bulk_out_endpointAddr && 309 ((endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK) 310 == USB_DIR_OUT) && 311 ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) 312 == USB_ENDPOINT_XFER_BULK)) { 313 /* we found a bulk out endpoint */ 314 dev->bulk_out_endpointAddr = endpoint->bEndpointAddress; 315 } 316 } 317 if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) { 318 err("Could not find both bulk-in and bulk-out endpoints"); 319 goto error; 320 } 321 322 /* save our data pointer in this interface device */ 323 usb_set_intfdata(interface, dev); 324 325 /* we can register the device now, as it is ready */ 326 retval = usb_register_dev(interface, &skel_class); 327 if (retval) { 328 /* something prevented us from registering this driver */ 329 err("Not able to get a minor for this device."); 330 usb_set_intfdata(interface, NULL); 331 goto error; 332 } 333 334 /* let the user know what node this device is now attached to */ 335 info("USB Skeleton device now attached to USBSkel-%d", interface->minor); 336 return 0; 337 338 error: 339 if (dev) 340 kref_put(&dev->kref, skel_delete); 341 return retval; 342 } 343 344 static void skel_disconnect(struct usb_interface *interface) 345 { 346 struct usb_skel *dev; 347 int minor = interface->minor; 348 349 /* prevent skel_open() from racing skel_disconnect() */ 350 lock_kernel(); 351 352 dev = usb_get_intfdata(interface); 353 usb_set_intfdata(interface, NULL); 354 355 /* give back our minor */ 356 usb_deregister_dev(interface, &skel_class); 357 358 /* prevent more I/O from starting */ 359 mutex_lock(&dev->io_mutex); 360 dev->interface = NULL; 361 mutex_unlock(&dev->io_mutex); 362 363 unlock_kernel(); 364 365 /* decrement our usage count */ 366 kref_put(&dev->kref, skel_delete); 367 368 info("USB Skeleton #%d now disconnected", minor); 369 } 370 371 static struct usb_driver skel_driver = { 372 .name = "skeleton", 373 .probe = skel_probe, 374 .disconnect = skel_disconnect, 375 .id_table = skel_table, 376 }; 377 378 static int __init usb_skel_init(void) 379 { 380 int result; 381 382 /* register this driver with the USB subsystem */ 383 result = usb_register(&skel_driver); 384 if (result) 385 err("usb_register failed. Error number %d", result); 386 387 return result; 388 } 389 390 static void __exit usb_skel_exit(void) 391 { 392 /* deregister this driver with the USB subsystem */ 393 usb_deregister(&skel_driver); 394 } 395 396 module_init (usb_skel_init); 397 module_exit (usb_skel_exit); 398 399 MODULE_LICENSE("GPL"); 400