usb-skeleton.c 10 KB

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  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. #include <linux/kernel.h>
  15. #include <linux/errno.h>
  16. #include <linux/init.h>
  17. #include <linux/slab.h>
  18. #include <linux/module.h>
  19. #include <linux/kref.h>
  20. #include <asm/uaccess.h>
  21. #include <linux/usb.h>
  22. #include <linux/mutex.h>
  23. /* Define these values to match your devices */
  24. #define USB_SKEL_VENDOR_ID 0xfff0
  25. #define USB_SKEL_PRODUCT_ID 0xfff0
  26. /* table of devices that work with this driver */
  27. static struct usb_device_id skel_table [] = {
  28. { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
  29. { } /* Terminating entry */
  30. };
  31. MODULE_DEVICE_TABLE(usb, skel_table);
  32. /* Get a minor range for your devices from the usb maintainer */
  33. #define USB_SKEL_MINOR_BASE 192
  34. /* our private defines. if this grows any larger, use your own .h file */
  35. #define MAX_TRANSFER (PAGE_SIZE - 512)
  36. #define WRITES_IN_FLIGHT 8
  37. /* Structure to hold all of our device specific stuff */
  38. struct usb_skel {
  39. struct usb_device *dev; /* the usb device for this device */
  40. struct usb_interface *interface; /* the interface for this device */
  41. struct semaphore limit_sem; /* limiting the number of writes in progress */
  42. unsigned char *bulk_in_buffer; /* the buffer to receive data */
  43. size_t bulk_in_size; /* the size of the receive buffer */
  44. __u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */
  45. __u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */
  46. struct kref kref;
  47. struct mutex io_mutex; /* synchronize I/O with disconnect */
  48. };
  49. #define to_skel_dev(d) container_of(d, struct usb_skel, kref)
  50. static struct usb_driver skel_driver;
  51. static void skel_delete(struct kref *kref)
  52. {
  53. struct usb_skel *dev = to_skel_dev(kref);
  54. usb_put_dev(dev->udev);
  55. kfree(dev->bulk_in_buffer);
  56. kfree(dev);
  57. }
  58. static int skel_open(struct inode *inode, struct file *file)
  59. {
  60. struct usb_skel *dev;
  61. struct usb_interface *interface;
  62. int subminor;
  63. int retval = 0;
  64. subminor = iminor(inode);
  65. interface = usb_find_interface(&skel_driver, subminor);
  66. if (!interface) {
  67. err ("%s - error, can't find device for minor %d",
  68. __FUNCTION__, subminor);
  69. retval = -ENODEV;
  70. goto exit;
  71. }
  72. dev = usb_get_intfdata(interface);
  73. if (!dev) {
  74. retval = -ENODEV;
  75. goto exit;
  76. }
  77. /* increment our usage count for the device */
  78. kref_get(&dev->kref);
  79. /* prevent the device from being autosuspended */
  80. retval = usb_autopm_get_interface(interface);
  81. if (retval) {
  82. kref_put(&dev->kref, skel_delete);
  83. goto exit;
  84. }
  85. /* save our object in the file's private structure */
  86. file->private_data = dev;
  87. exit:
  88. return retval;
  89. }
  90. static int skel_release(struct inode *inode, struct file *file)
  91. {
  92. struct usb_skel *dev;
  93. dev = (struct usb_skel *)file->private_data;
  94. if (dev == NULL)
  95. return -ENODEV;
  96. /* allow the device to be autosuspended */
  97. mutex_lock(&dev->io_mutex);
  98. if (dev->interface)
  99. usb_autopm_put_interface(dev->interface);
  100. mutex_unlock(&dev->io_mutex);
  101. /* decrement the count on our device */
  102. kref_put(&dev->kref, skel_delete);
  103. return 0;
  104. }
  105. static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos)
  106. {
  107. struct usb_skel *dev;
  108. int retval;
  109. int bytes_read;
  110. dev = (struct usb_skel *)file->private_data;
  111. mutex_lock(&dev->io_mutex);
  112. if (!dev->interface) { /* disconnect() was called */
  113. retval = -ENODEV;
  114. goto exit;
  115. }
  116. /* do a blocking bulk read to get data from the device */
  117. retval = usb_bulk_msg(dev->udev,
  118. usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
  119. dev->bulk_in_buffer,
  120. min(dev->bulk_in_size, count),
  121. &bytes_read, 10000);
  122. /* if the read was successful, copy the data to userspace */
  123. if (!retval) {
  124. if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
  125. retval = -EFAULT;
  126. else
  127. retval = bytes_read;
  128. }
  129. exit:
  130. mutex_unlock(&dev->io_mutex);
  131. return retval;
  132. }
  133. static void skel_write_bulk_callback(struct urb *urb)
  134. {
  135. struct usb_skel *dev;
  136. dev = (struct usb_skel *)urb->context;
  137. /* sync/async unlink faults aren't errors */
  138. if (urb->status &&
  139. !(urb->status == -ENOENT ||
  140. urb->status == -ECONNRESET ||
  141. urb->status == -ESHUTDOWN)) {
  142. err("%s - nonzero write bulk status received: %d",
  143. __FUNCTION__, urb->status);
  144. }
  145. /* free up our allocated buffer */
  146. usb_buffer_free(urb->dev, urb->transfer_buffer_length,
  147. urb->transfer_buffer, urb->transfer_dma);
  148. up(&dev->limit_sem);
  149. }
  150. static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos)
  151. {
  152. struct usb_skel *dev;
  153. int retval = 0;
  154. struct urb *urb = NULL;
  155. char *buf = NULL;
  156. size_t writesize = min(count, (size_t)MAX_TRANSFER);
  157. dev = (struct usb_skel *)file->private_data;
  158. /* verify that we actually have some data to write */
  159. if (count == 0)
  160. goto exit;
  161. /* limit the number of URBs in flight to stop a user from using up all RAM */
  162. if (down_interruptible(&dev->limit_sem)) {
  163. retval = -ERESTARTSYS;
  164. goto exit;
  165. }
  166. mutex_lock(&dev->io_mutex);
  167. if (!dev->interface) { /* disconnect() was called */
  168. retval = -ENODEV;
  169. goto error;
  170. }
  171. /* create a urb, and a buffer for it, and copy the data to the urb */
  172. urb = usb_alloc_urb(0, GFP_KERNEL);
  173. if (!urb) {
  174. retval = -ENOMEM;
  175. goto error;
  176. }
  177. buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma);
  178. if (!buf) {
  179. retval = -ENOMEM;
  180. goto error;
  181. }
  182. if (copy_from_user(buf, user_buffer, writesize)) {
  183. retval = -EFAULT;
  184. goto error;
  185. }
  186. /* initialize the urb properly */
  187. usb_fill_bulk_urb(urb, dev->udev,
  188. usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
  189. buf, writesize, skel_write_bulk_callback, dev);
  190. urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
  191. /* send the data out the bulk port */
  192. retval = usb_submit_urb(urb, GFP_KERNEL);
  193. if (retval) {
  194. err("%s - failed submitting write urb, error %d", __FUNCTION__, retval);
  195. goto error;
  196. }
  197. /* release our reference to this urb, the USB core will eventually free it entirely */
  198. usb_free_urb(urb);
  199. mutex_unlock(&dev->io_mutex);
  200. return writesize;
  201. error:
  202. if (urb) {
  203. usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
  204. usb_free_urb(urb);
  205. }
  206. mutex_unlock(&dev->io_mutex);
  207. up(&dev->limit_sem);
  208. exit:
  209. return retval;
  210. }
  211. static const struct file_operations skel_fops = {
  212. .owner = THIS_MODULE,
  213. .read = skel_read,
  214. .write = skel_write,
  215. .open = skel_open,
  216. .release = skel_release,
  217. };
  218. /*
  219. * usb class driver info in order to get a minor number from the usb core,
  220. * and to have the device registered with the driver core
  221. */
  222. static struct usb_class_driver skel_class = {
  223. .name = "skel%d",
  224. .fops = &skel_fops,
  225. .minor_base = USB_SKEL_MINOR_BASE,
  226. };
  227. static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id)
  228. {
  229. struct usb_skel *dev;
  230. struct usb_host_interface *iface_desc;
  231. struct usb_endpoint_descriptor *endpoint;
  232. size_t buffer_size;
  233. int i;
  234. int retval = -ENOMEM;
  235. /* allocate memory for our device state and initialize it */
  236. dev = kzalloc(sizeof(*dev), GFP_KERNEL);
  237. if (!dev) {
  238. err("Out of memory");
  239. goto error;
  240. }
  241. kref_init(&dev->kref);
  242. sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
  243. mutex_init(&dev->io_mutex);
  244. dev->udev = usb_get_dev(interface_to_usbdev(interface));
  245. dev->interface = interface;
  246. /* set up the endpoint information */
  247. /* use only the first bulk-in and bulk-out endpoints */
  248. iface_desc = interface->cur_altsetting;
  249. for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
  250. endpoint = &iface_desc->endpoint[i].desc;
  251. if (!dev->bulk_in_endpointAddr &&
  252. usb_endpoint_is_bulk_in(endpoint)) {
  253. /* we found a bulk in endpoint */
  254. buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
  255. dev->bulk_in_size = buffer_size;
  256. dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
  257. dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
  258. if (!dev->bulk_in_buffer) {
  259. err("Could not allocate bulk_in_buffer");
  260. goto error;
  261. }
  262. }
  263. if (!dev->bulk_out_endpointAddr &&
  264. usb_endpoint_is_bulk_out(endpoint)) {
  265. /* we found a bulk out endpoint */
  266. dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
  267. }
  268. }
  269. if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
  270. err("Could not find both bulk-in and bulk-out endpoints");
  271. goto error;
  272. }
  273. /* save our data pointer in this interface device */
  274. usb_set_intfdata(interface, dev);
  275. /* we can register the device now, as it is ready */
  276. retval = usb_register_dev(interface, &skel_class);
  277. if (retval) {
  278. /* something prevented us from registering this driver */
  279. err("Not able to get a minor for this device.");
  280. usb_set_intfdata(interface, NULL);
  281. goto error;
  282. }
  283. /* let the user know what node this device is now attached to */
  284. info("USB Skeleton device now attached to USBSkel-%d", interface->minor);
  285. return 0;
  286. error:
  287. if (dev)
  288. kref_put(&dev->kref, skel_delete);
  289. return retval;
  290. }
  291. static void skel_disconnect(struct usb_interface *interface)
  292. {
  293. struct usb_skel *dev;
  294. int minor = interface->minor;
  295. /* prevent skel_open() from racing skel_disconnect() */
  296. lock_kernel();
  297. dev = usb_get_intfdata(interface);
  298. usb_set_intfdata(interface, NULL);
  299. /* give back our minor */
  300. usb_deregister_dev(interface, &skel_class);
  301. /* prevent more I/O from starting */
  302. mutex_lock(&dev->io_mutex);
  303. dev->interface = NULL;
  304. mutex_unlock(&dev->io_mutex);
  305. unlock_kernel();
  306. /* decrement our usage count */
  307. kref_put(&dev->kref, skel_delete);
  308. info("USB Skeleton #%d now disconnected", minor);
  309. }
  310. static struct usb_driver skel_driver = {
  311. .name = "skeleton",
  312. .probe = skel_probe,
  313. .disconnect = skel_disconnect,
  314. .id_table = skel_table,
  315. };
  316. static int __init usb_skel_init(void)
  317. {
  318. int result;
  319. /* register this driver with the USB subsystem */
  320. result = usb_register(&skel_driver);
  321. if (result)
  322. err("usb_register failed. Error number %d", result);
  323. return result;
  324. }
  325. static void __exit usb_skel_exit(void)
  326. {
  327. /* deregister this driver with the USB subsystem */
  328. usb_deregister(&skel_driver);
  329. }
  330. module_init(usb_skel_init);
  331. module_exit(usb_skel_exit);
  332. MODULE_LICENSE("GPL");