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 /* MAX_TRANSFER is chosen so that the VM is not stressed by
44 allocations > PAGE_SIZE and the number of packets in a page
45 is an integer 512 is the largest possible packet on EHCI */
46 #define WRITES_IN_FLIGHT 8
47 /* arbitrarily chosen */
48
49 /* Structure to hold all of our device specific stuff */
50 struct usb_skel {
51 struct usb_device *udev; /* the usb device for this device */
52 struct usb_interface *interface; /* the interface for this device */
53 struct semaphore limit_sem; /* limiting the number of writes in progress */
54 struct usb_anchor submitted; /* in case we need to retract our submissions */
55 unsigned char *bulk_in_buffer; /* the buffer to receive data */
56 size_t bulk_in_size; /* the size of the receive buffer */
57 __u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */
58 __u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */
59 int errors; /* the last request tanked */
60 int open_count; /* count the number of openers */
61 spinlock_t err_lock; /* lock for errors */
62 struct kref kref;
63 struct mutex io_mutex; /* synchronize I/O with disconnect */
64 };
65 #define to_skel_dev(d) container_of(d, struct usb_skel, kref)
66
67 static struct usb_driver skel_driver;
68 static void skel_draw_down(struct usb_skel *dev);
69
70 static void skel_delete(struct kref *kref)
71 {
72 struct usb_skel *dev = to_skel_dev(kref);
73
74 usb_put_dev(dev->udev);
75 kfree(dev->bulk_in_buffer);
76 kfree(dev);
77 }
78
79 static int skel_open(struct inode *inode, struct file *file)
80 {
81 struct usb_skel *dev;
82 struct usb_interface *interface;
83 int subminor;
84 int retval = 0;
85
86 subminor = iminor(inode);
87
88 interface = usb_find_interface(&skel_driver, subminor);
89 if (!interface) {
90 err ("%s - error, can't find device for minor %d",
91 __func__, subminor);
92 retval = -ENODEV;
93 goto exit;
94 }
95
96 dev = usb_get_intfdata(interface);
97 if (!dev) {
98 retval = -ENODEV;
99 goto exit;
100 }
101
102 /* increment our usage count for the device */
103 kref_get(&dev->kref);
104
105 /* lock the device to allow correctly handling errors
106 * in resumption */
107 mutex_lock(&dev->io_mutex);
108
109 if (!dev->open_count++) {
110 retval = usb_autopm_get_interface(interface);
111 if (retval) {
112 dev->open_count--;
113 mutex_unlock(&dev->io_mutex);
114 kref_put(&dev->kref, skel_delete);
115 goto exit;
116 }
117 } /* else { //uncomment this block if you want exclusive open
118 retval = -EBUSY;
119 dev->open_count--;
120 mutex_unlock(&dev->io_mutex);
121 kref_put(&dev->kref, skel_delete);
122 goto exit;
123 } */
124 /* prevent the device from being autosuspended */
125
126 /* save our object in the file's private structure */
127 file->private_data = dev;
128 mutex_unlock(&dev->io_mutex);
129
130 exit:
131 return retval;
132 }
133
134 static int skel_release(struct inode *inode, struct file *file)
135 {
136 struct usb_skel *dev;
137
138 dev = (struct usb_skel *)file->private_data;
139 if (dev == NULL)
140 return -ENODEV;
141
142 /* allow the device to be autosuspended */
143 mutex_lock(&dev->io_mutex);
144 if (!--dev->open_count && dev->interface)
145 usb_autopm_put_interface(dev->interface);
146 mutex_unlock(&dev->io_mutex);
147
148 /* decrement the count on our device */
149 kref_put(&dev->kref, skel_delete);
150 return 0;
151 }
152
153 static int skel_flush(struct file *file, fl_owner_t id)
154 {
155 struct usb_skel *dev;
156 int res;
157
158 dev = (struct usb_skel *)file->private_data;
159 if (dev == NULL)
160 return -ENODEV;
161
162 /* wait for io to stop */
163 mutex_lock(&dev->io_mutex);
164 skel_draw_down(dev);
165
166 /* read out errors, leave subsequent opens a clean slate */
167 spin_lock_irq(&dev->err_lock);
168 res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
169 dev->errors = 0;
170 spin_unlock_irq(&dev->err_lock);
171
172 mutex_unlock(&dev->io_mutex);
173
174 return res;
175 }
176
177 static ssize_t skel_read(struct file *file, char *buffer, size_t count, loff_t *ppos)
178 {
179 struct usb_skel *dev;
180 int retval;
181 int bytes_read;
182
183 dev = (struct usb_skel *)file->private_data;
184
185 mutex_lock(&dev->io_mutex);
186 if (!dev->interface) { /* disconnect() was called */
187 retval = -ENODEV;
188 goto exit;
189 }
190
191 /* do a blocking bulk read to get data from the device */
192 retval = usb_bulk_msg(dev->udev,
193 usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
194 dev->bulk_in_buffer,
195 min(dev->bulk_in_size, count),
196 &bytes_read, 10000);
197
198 /* if the read was successful, copy the data to userspace */
199 if (!retval) {
200 if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
201 retval = -EFAULT;
202 else
203 retval = bytes_read;
204 }
205
206 exit:
207 mutex_unlock(&dev->io_mutex);
208 return retval;
209 }
210
211 static void skel_write_bulk_callback(struct urb *urb)
212 {
213 struct usb_skel *dev;
214
215 dev = urb->context;
216
217 /* sync/async unlink faults aren't errors */
218 if (urb->status) {
219 if(!(urb->status == -ENOENT ||
220 urb->status == -ECONNRESET ||
221 urb->status == -ESHUTDOWN))
222 err("%s - nonzero write bulk status received: %d",
223 __func__, urb->status);
224
225 spin_lock(&dev->err_lock);
226 dev->errors = urb->status;
227 spin_unlock(&dev->err_lock);
228 }
229
230 /* free up our allocated buffer */
231 usb_buffer_free(urb->dev, urb->transfer_buffer_length,
232 urb->transfer_buffer, urb->transfer_dma);
233 up(&dev->limit_sem);
234 }
235
236 static ssize_t skel_write(struct file *file, const char *user_buffer, size_t count, loff_t *ppos)
237 {
238 struct usb_skel *dev;
239 int retval = 0;
240 struct urb *urb = NULL;
241 char *buf = NULL;
242 size_t writesize = min(count, (size_t)MAX_TRANSFER);
243
244 dev = (struct usb_skel *)file->private_data;
245
246 /* verify that we actually have some data to write */
247 if (count == 0)
248 goto exit;
249
250 /* limit the number of URBs in flight to stop a user from using up all RAM */
251 if (down_interruptible(&dev->limit_sem)) {
252 retval = -ERESTARTSYS;
253 goto exit;
254 }
255
256 spin_lock_irq(&dev->err_lock);
257 if ((retval = dev->errors) < 0) {
258 /* any error is reported once */
259 dev->errors = 0;
260 /* to preserve notifications about reset */
261 retval = (retval == -EPIPE) ? retval : -EIO;
262 }
263 spin_unlock_irq(&dev->err_lock);
264 if (retval < 0)
265 goto error;
266
267 /* create a urb, and a buffer for it, and copy the data to the urb */
268 urb = usb_alloc_urb(0, GFP_KERNEL);
269 if (!urb) {
270 retval = -ENOMEM;
271 goto error;
272 }
273
274 buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL, &urb->transfer_dma);
275 if (!buf) {
276 retval = -ENOMEM;
277 goto error;
278 }
279
280 if (copy_from_user(buf, user_buffer, writesize)) {
281 retval = -EFAULT;
282 goto error;
283 }
284
285 /* this lock makes sure we don't submit URBs to gone devices */
286 mutex_lock(&dev->io_mutex);
287 if (!dev->interface) { /* disconnect() was called */
288 mutex_unlock(&dev->io_mutex);
289 retval = -ENODEV;
290 goto error;
291 }
292
293 /* initialize the urb properly */
294 usb_fill_bulk_urb(urb, dev->udev,
295 usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
296 buf, writesize, skel_write_bulk_callback, dev);
297 urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
298 usb_anchor_urb(urb, &dev->submitted);
299
300 /* send the data out the bulk port */
301 retval = usb_submit_urb(urb, GFP_KERNEL);
302 mutex_unlock(&dev->io_mutex);
303 if (retval) {
304 err("%s - failed submitting write urb, error %d", __func__, retval);
305 goto error_unanchor;
306 }
307
308 /* release our reference to this urb, the USB core will eventually free it entirely */
309 usb_free_urb(urb);
310
311
312 return writesize;
313
314 error_unanchor:
315 usb_unanchor_urb(urb);
316 error:
317 if (urb) {
318 usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
319 usb_free_urb(urb);
320 }
321 up(&dev->limit_sem);
322
323 exit:
324 return retval;
325 }
326
327 static const struct file_operations skel_fops = {
328 .owner = THIS_MODULE,
329 .read = skel_read,
330 .write = skel_write,
331 .open = skel_open,
332 .release = skel_release,
333 .flush = skel_flush,
334 };
335
336 /*
337 * usb class driver info in order to get a minor number from the usb core,
338 * and to have the device registered with the driver core
339 */
340 static struct usb_class_driver skel_class = {
341 .name = "skel%d",
342 .fops = &skel_fops,
343 .minor_base = USB_SKEL_MINOR_BASE,
344 };
345
346 static int skel_probe(struct usb_interface *interface, const struct usb_device_id *id)
347 {
348 struct usb_skel *dev;
349 struct usb_host_interface *iface_desc;
350 struct usb_endpoint_descriptor *endpoint;
351 size_t buffer_size;
352 int i;
353 int retval = -ENOMEM;
354
355 /* allocate memory for our device state and initialize it */
356 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
357 if (!dev) {
358 err("Out of memory");
359 goto error;
360 }
361 kref_init(&dev->kref);
362 sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
363 mutex_init(&dev->io_mutex);
364 spin_lock_init(&dev->err_lock);
365 init_usb_anchor(&dev->submitted);
366
367 dev->udev = usb_get_dev(interface_to_usbdev(interface));
368 dev->interface = interface;
369
370 /* set up the endpoint information */
371 /* use only the first bulk-in and bulk-out endpoints */
372 iface_desc = interface->cur_altsetting;
373 for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
374 endpoint = &iface_desc->endpoint[i].desc;
375
376 if (!dev->bulk_in_endpointAddr &&
377 usb_endpoint_is_bulk_in(endpoint)) {
378 /* we found a bulk in endpoint */
379 buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
380 dev->bulk_in_size = buffer_size;
381 dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
382 dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
383 if (!dev->bulk_in_buffer) {
384 err("Could not allocate bulk_in_buffer");
385 goto error;
386 }
387 }
388
389 if (!dev->bulk_out_endpointAddr &&
390 usb_endpoint_is_bulk_out(endpoint)) {
391 /* we found a bulk out endpoint */
392 dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
393 }
394 }
395 if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
396 err("Could not find both bulk-in and bulk-out endpoints");
397 goto error;
398 }
399
400 /* save our data pointer in this interface device */
401 usb_set_intfdata(interface, dev);
402
403 /* we can register the device now, as it is ready */
404 retval = usb_register_dev(interface, &skel_class);
405 if (retval) {
406 /* something prevented us from registering this driver */
407 err("Not able to get a minor for this device.");
408 usb_set_intfdata(interface, NULL);
409 goto error;
410 }
411
412 /* let the user know what node this device is now attached to */
413 dev_info(&interface->dev,
414 "USB Skeleton device now attached to USBSkel-%d",
415 interface->minor);
416 return 0;
417
418 error:
419 if (dev)
420 /* this frees allocated memory */
421 kref_put(&dev->kref, skel_delete);
422 return retval;
423 }
424
425 static void skel_disconnect(struct usb_interface *interface)
426 {
427 struct usb_skel *dev;
428 int minor = interface->minor;
429
430 dev = usb_get_intfdata(interface);
431 usb_set_intfdata(interface, NULL);
432
433 /* give back our minor */
434 usb_deregister_dev(interface, &skel_class);
435
436 /* prevent more I/O from starting */
437 mutex_lock(&dev->io_mutex);
438 dev->interface = NULL;
439 mutex_unlock(&dev->io_mutex);
440
441 usb_kill_anchored_urbs(&dev->submitted);
442
443 /* decrement our usage count */
444 kref_put(&dev->kref, skel_delete);
445
446 dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
447 }
448
449 static void skel_draw_down(struct usb_skel *dev)
450 {
451 int time;
452
453 time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
454 if (!time)
455 usb_kill_anchored_urbs(&dev->submitted);
456 }
457
458 static int skel_suspend(struct usb_interface *intf, pm_message_t message)
459 {
460 struct usb_skel *dev = usb_get_intfdata(intf);
461
462 if (!dev)
463 return 0;
464 skel_draw_down(dev);
465 return 0;
466 }
467
468 static int skel_resume (struct usb_interface *intf)
469 {
470 return 0;
471 }
472
473 static int skel_pre_reset(struct usb_interface *intf)
474 {
475 struct usb_skel *dev = usb_get_intfdata(intf);
476
477 mutex_lock(&dev->io_mutex);
478 skel_draw_down(dev);
479
480 return 0;
481 }
482
483 static int skel_post_reset(struct usb_interface *intf)
484 {
485 struct usb_skel *dev = usb_get_intfdata(intf);
486
487 /* we are sure no URBs are active - no locking needed */
488 dev->errors = -EPIPE;
489 mutex_unlock(&dev->io_mutex);
490
491 return 0;
492 }
493
494 static struct usb_driver skel_driver = {
495 .name = "skeleton",
496 .probe = skel_probe,
497 .disconnect = skel_disconnect,
498 .suspend = skel_suspend,
499 .resume = skel_resume,
500 .pre_reset = skel_pre_reset,
501 .post_reset = skel_post_reset,
502 .id_table = skel_table,
503 .supports_autosuspend = 1,
504 };
505
506 static int __init usb_skel_init(void)
507 {
508 int result;
509
510 /* register this driver with the USB subsystem */
511 result = usb_register(&skel_driver);
512 if (result)
513 err("usb_register failed. Error number %d", result);
514
515 return result;
516 }
517
518 static void __exit usb_skel_exit(void)
519 {
520 /* deregister this driver with the USB subsystem */
521 usb_deregister(&skel_driver);
522 }
523
524 module_init(usb_skel_init);
525 module_exit(usb_skel_exit);
526
527 MODULE_LICENSE("GPL");
528
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