Version:  2.0.40 2.2.26 2.4.37 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9

Linux/drivers/usb/class/cdc-wdm.c

  1 /*
  2  * cdc-wdm.c
  3  *
  4  * This driver supports USB CDC WCM Device Management.
  5  *
  6  * Copyright (c) 2007-2009 Oliver Neukum
  7  *
  8  * Some code taken from cdc-acm.c
  9  *
 10  * Released under the GPLv2.
 11  *
 12  * Many thanks to Carl Nordbeck
 13  */
 14 #include <linux/kernel.h>
 15 #include <linux/errno.h>
 16 #include <linux/ioctl.h>
 17 #include <linux/slab.h>
 18 #include <linux/module.h>
 19 #include <linux/mutex.h>
 20 #include <linux/uaccess.h>
 21 #include <linux/bitops.h>
 22 #include <linux/poll.h>
 23 #include <linux/usb.h>
 24 #include <linux/usb/cdc.h>
 25 #include <asm/byteorder.h>
 26 #include <asm/unaligned.h>
 27 #include <linux/usb/cdc-wdm.h>
 28 
 29 /*
 30  * Version Information
 31  */
 32 #define DRIVER_VERSION "v0.03"
 33 #define DRIVER_AUTHOR "Oliver Neukum"
 34 #define DRIVER_DESC "USB Abstract Control Model driver for USB WCM Device Management"
 35 
 36 static const struct usb_device_id wdm_ids[] = {
 37         {
 38                 .match_flags = USB_DEVICE_ID_MATCH_INT_CLASS |
 39                                  USB_DEVICE_ID_MATCH_INT_SUBCLASS,
 40                 .bInterfaceClass = USB_CLASS_COMM,
 41                 .bInterfaceSubClass = USB_CDC_SUBCLASS_DMM
 42         },
 43         { }
 44 };
 45 
 46 MODULE_DEVICE_TABLE (usb, wdm_ids);
 47 
 48 #define WDM_MINOR_BASE  176
 49 
 50 
 51 #define WDM_IN_USE              1
 52 #define WDM_DISCONNECTING       2
 53 #define WDM_RESULT              3
 54 #define WDM_READ                4
 55 #define WDM_INT_STALL           5
 56 #define WDM_POLL_RUNNING        6
 57 #define WDM_RESPONDING          7
 58 #define WDM_SUSPENDING          8
 59 #define WDM_RESETTING           9
 60 #define WDM_OVERFLOW            10
 61 #define WDM_DRAIN_ON_OPEN       11
 62 
 63 #define WDM_MAX                 16
 64 
 65 /* CDC-WMC r1.1 requires wMaxCommand to be "at least 256 decimal (0x100)" */
 66 #define WDM_DEFAULT_BUFSIZE     256
 67 
 68 static DEFINE_MUTEX(wdm_mutex);
 69 static DEFINE_SPINLOCK(wdm_device_list_lock);
 70 static LIST_HEAD(wdm_device_list);
 71 
 72 /* --- method tables --- */
 73 
 74 struct wdm_device {
 75         u8                      *inbuf; /* buffer for response */
 76         u8                      *outbuf; /* buffer for command */
 77         u8                      *sbuf; /* buffer for status */
 78         u8                      *ubuf; /* buffer for copy to user space */
 79 
 80         struct urb              *command;
 81         struct urb              *response;
 82         struct urb              *validity;
 83         struct usb_interface    *intf;
 84         struct usb_ctrlrequest  *orq;
 85         struct usb_ctrlrequest  *irq;
 86         spinlock_t              iuspin;
 87 
 88         unsigned long           flags;
 89         u16                     bufsize;
 90         u16                     wMaxCommand;
 91         u16                     wMaxPacketSize;
 92         __le16                  inum;
 93         int                     reslength;
 94         int                     length;
 95         int                     read;
 96         int                     count;
 97         dma_addr_t              shandle;
 98         dma_addr_t              ihandle;
 99         struct mutex            wlock;
100         struct mutex            rlock;
101         wait_queue_head_t       wait;
102         struct work_struct      rxwork;
103         int                     werr;
104         int                     rerr;
105         int                     resp_count;
106 
107         struct list_head        device_list;
108         int                     (*manage_power)(struct usb_interface *, int);
109 };
110 
111 static struct usb_driver wdm_driver;
112 
113 /* return intfdata if we own the interface, else look up intf in the list */
114 static struct wdm_device *wdm_find_device(struct usb_interface *intf)
115 {
116         struct wdm_device *desc;
117 
118         spin_lock(&wdm_device_list_lock);
119         list_for_each_entry(desc, &wdm_device_list, device_list)
120                 if (desc->intf == intf)
121                         goto found;
122         desc = NULL;
123 found:
124         spin_unlock(&wdm_device_list_lock);
125 
126         return desc;
127 }
128 
129 static struct wdm_device *wdm_find_device_by_minor(int minor)
130 {
131         struct wdm_device *desc;
132 
133         spin_lock(&wdm_device_list_lock);
134         list_for_each_entry(desc, &wdm_device_list, device_list)
135                 if (desc->intf->minor == minor)
136                         goto found;
137         desc = NULL;
138 found:
139         spin_unlock(&wdm_device_list_lock);
140 
141         return desc;
142 }
143 
144 /* --- callbacks --- */
145 static void wdm_out_callback(struct urb *urb)
146 {
147         struct wdm_device *desc;
148         desc = urb->context;
149         spin_lock(&desc->iuspin);
150         desc->werr = urb->status;
151         spin_unlock(&desc->iuspin);
152         kfree(desc->outbuf);
153         desc->outbuf = NULL;
154         clear_bit(WDM_IN_USE, &desc->flags);
155         wake_up(&desc->wait);
156 }
157 
158 /* forward declaration */
159 static int service_outstanding_interrupt(struct wdm_device *desc);
160 
161 static void wdm_in_callback(struct urb *urb)
162 {
163         struct wdm_device *desc = urb->context;
164         int status = urb->status;
165         int length = urb->actual_length;
166 
167         spin_lock(&desc->iuspin);
168         clear_bit(WDM_RESPONDING, &desc->flags);
169 
170         if (status) {
171                 switch (status) {
172                 case -ENOENT:
173                         dev_dbg(&desc->intf->dev,
174                                 "nonzero urb status received: -ENOENT\n");
175                         goto skip_error;
176                 case -ECONNRESET:
177                         dev_dbg(&desc->intf->dev,
178                                 "nonzero urb status received: -ECONNRESET\n");
179                         goto skip_error;
180                 case -ESHUTDOWN:
181                         dev_dbg(&desc->intf->dev,
182                                 "nonzero urb status received: -ESHUTDOWN\n");
183                         goto skip_error;
184                 case -EPIPE:
185                         dev_dbg(&desc->intf->dev,
186                                 "nonzero urb status received: -EPIPE\n");
187                         break;
188                 default:
189                         dev_err(&desc->intf->dev,
190                                 "Unexpected error %d\n", status);
191                         break;
192                 }
193         }
194 
195         /*
196          * only set a new error if there is no previous error.
197          * Errors are only cleared during read/open
198          */
199         if (desc->rerr  == 0)
200                 desc->rerr = status;
201 
202         if (length + desc->length > desc->wMaxCommand) {
203                 /* The buffer would overflow */
204                 set_bit(WDM_OVERFLOW, &desc->flags);
205         } else {
206                 /* we may already be in overflow */
207                 if (!test_bit(WDM_OVERFLOW, &desc->flags)) {
208                         memmove(desc->ubuf + desc->length, desc->inbuf, length);
209                         desc->length += length;
210                         desc->reslength = length;
211                 }
212         }
213 
214         /*
215          * Handling devices with the WDM_DRAIN_ON_OPEN flag set:
216          * If desc->resp_count is unset, then the urb was submitted
217          * without a prior notification.  If the device returned any
218          * data, then this implies that it had messages queued without
219          * notifying us.  Continue reading until that queue is flushed.
220          */
221         if (!desc->resp_count) {
222                 if (!length) {
223                         /* do not propagate the expected -EPIPE */
224                         desc->rerr = 0;
225                         goto unlock;
226                 }
227                 dev_dbg(&desc->intf->dev, "got %d bytes without notification\n", length);
228                 set_bit(WDM_RESPONDING, &desc->flags);
229                 usb_submit_urb(desc->response, GFP_ATOMIC);
230         }
231 
232 skip_error:
233         set_bit(WDM_READ, &desc->flags);
234         wake_up(&desc->wait);
235 
236         if (desc->rerr) {
237                 /*
238                  * Since there was an error, userspace may decide to not read
239                  * any data after poll'ing.
240                  * We should respond to further attempts from the device to send
241                  * data, so that we can get unstuck.
242                  */
243                 service_outstanding_interrupt(desc);
244         }
245 
246 unlock:
247         spin_unlock(&desc->iuspin);
248 }
249 
250 static void wdm_int_callback(struct urb *urb)
251 {
252         int rv = 0;
253         int responding;
254         int status = urb->status;
255         struct wdm_device *desc;
256         struct usb_cdc_notification *dr;
257 
258         desc = urb->context;
259         dr = (struct usb_cdc_notification *)desc->sbuf;
260 
261         if (status) {
262                 switch (status) {
263                 case -ESHUTDOWN:
264                 case -ENOENT:
265                 case -ECONNRESET:
266                         return; /* unplug */
267                 case -EPIPE:
268                         set_bit(WDM_INT_STALL, &desc->flags);
269                         dev_err(&desc->intf->dev, "Stall on int endpoint\n");
270                         goto sw; /* halt is cleared in work */
271                 default:
272                         dev_err(&desc->intf->dev,
273                                 "nonzero urb status received: %d\n", status);
274                         break;
275                 }
276         }
277 
278         if (urb->actual_length < sizeof(struct usb_cdc_notification)) {
279                 dev_err(&desc->intf->dev, "wdm_int_callback - %d bytes\n",
280                         urb->actual_length);
281                 goto exit;
282         }
283 
284         switch (dr->bNotificationType) {
285         case USB_CDC_NOTIFY_RESPONSE_AVAILABLE:
286                 dev_dbg(&desc->intf->dev,
287                         "NOTIFY_RESPONSE_AVAILABLE received: index %d len %d\n",
288                         le16_to_cpu(dr->wIndex), le16_to_cpu(dr->wLength));
289                 break;
290 
291         case USB_CDC_NOTIFY_NETWORK_CONNECTION:
292 
293                 dev_dbg(&desc->intf->dev,
294                         "NOTIFY_NETWORK_CONNECTION %s network\n",
295                         dr->wValue ? "connected to" : "disconnected from");
296                 goto exit;
297         case USB_CDC_NOTIFY_SPEED_CHANGE:
298                 dev_dbg(&desc->intf->dev, "SPEED_CHANGE received (len %u)\n",
299                         urb->actual_length);
300                 goto exit;
301         default:
302                 clear_bit(WDM_POLL_RUNNING, &desc->flags);
303                 dev_err(&desc->intf->dev,
304                         "unknown notification %d received: index %d len %d\n",
305                         dr->bNotificationType,
306                         le16_to_cpu(dr->wIndex),
307                         le16_to_cpu(dr->wLength));
308                 goto exit;
309         }
310 
311         spin_lock(&desc->iuspin);
312         responding = test_and_set_bit(WDM_RESPONDING, &desc->flags);
313         if (!desc->resp_count++ && !responding
314                 && !test_bit(WDM_DISCONNECTING, &desc->flags)
315                 && !test_bit(WDM_SUSPENDING, &desc->flags)) {
316                 rv = usb_submit_urb(desc->response, GFP_ATOMIC);
317                 dev_dbg(&desc->intf->dev, "submit response URB %d\n", rv);
318         }
319         spin_unlock(&desc->iuspin);
320         if (rv < 0) {
321                 clear_bit(WDM_RESPONDING, &desc->flags);
322                 if (rv == -EPERM)
323                         return;
324                 if (rv == -ENOMEM) {
325 sw:
326                         rv = schedule_work(&desc->rxwork);
327                         if (rv)
328                                 dev_err(&desc->intf->dev,
329                                         "Cannot schedule work\n");
330                 }
331         }
332 exit:
333         rv = usb_submit_urb(urb, GFP_ATOMIC);
334         if (rv)
335                 dev_err(&desc->intf->dev,
336                         "%s - usb_submit_urb failed with result %d\n",
337                         __func__, rv);
338 
339 }
340 
341 static void kill_urbs(struct wdm_device *desc)
342 {
343         /* the order here is essential */
344         usb_kill_urb(desc->command);
345         usb_kill_urb(desc->validity);
346         usb_kill_urb(desc->response);
347 }
348 
349 static void free_urbs(struct wdm_device *desc)
350 {
351         usb_free_urb(desc->validity);
352         usb_free_urb(desc->response);
353         usb_free_urb(desc->command);
354 }
355 
356 static void cleanup(struct wdm_device *desc)
357 {
358         kfree(desc->sbuf);
359         kfree(desc->inbuf);
360         kfree(desc->orq);
361         kfree(desc->irq);
362         kfree(desc->ubuf);
363         free_urbs(desc);
364         kfree(desc);
365 }
366 
367 static ssize_t wdm_write
368 (struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
369 {
370         u8 *buf;
371         int rv = -EMSGSIZE, r, we;
372         struct wdm_device *desc = file->private_data;
373         struct usb_ctrlrequest *req;
374 
375         if (count > desc->wMaxCommand)
376                 count = desc->wMaxCommand;
377 
378         spin_lock_irq(&desc->iuspin);
379         we = desc->werr;
380         desc->werr = 0;
381         spin_unlock_irq(&desc->iuspin);
382         if (we < 0)
383                 return usb_translate_errors(we);
384 
385         buf = kmalloc(count, GFP_KERNEL);
386         if (!buf) {
387                 rv = -ENOMEM;
388                 goto outnl;
389         }
390 
391         r = copy_from_user(buf, buffer, count);
392         if (r > 0) {
393                 rv = -EFAULT;
394                 goto out_free_mem;
395         }
396 
397         /* concurrent writes and disconnect */
398         r = mutex_lock_interruptible(&desc->wlock);
399         rv = -ERESTARTSYS;
400         if (r)
401                 goto out_free_mem;
402 
403         if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
404                 rv = -ENODEV;
405                 goto out_free_mem_lock;
406         }
407 
408         r = usb_autopm_get_interface(desc->intf);
409         if (r < 0) {
410                 rv = usb_translate_errors(r);
411                 goto out_free_mem_lock;
412         }
413 
414         if (!(file->f_flags & O_NONBLOCK))
415                 r = wait_event_interruptible(desc->wait, !test_bit(WDM_IN_USE,
416                                                                 &desc->flags));
417         else
418                 if (test_bit(WDM_IN_USE, &desc->flags))
419                         r = -EAGAIN;
420 
421         if (test_bit(WDM_RESETTING, &desc->flags))
422                 r = -EIO;
423 
424         if (r < 0) {
425                 rv = r;
426                 goto out_free_mem_pm;
427         }
428 
429         req = desc->orq;
430         usb_fill_control_urb(
431                 desc->command,
432                 interface_to_usbdev(desc->intf),
433                 /* using common endpoint 0 */
434                 usb_sndctrlpipe(interface_to_usbdev(desc->intf), 0),
435                 (unsigned char *)req,
436                 buf,
437                 count,
438                 wdm_out_callback,
439                 desc
440         );
441 
442         req->bRequestType = (USB_DIR_OUT | USB_TYPE_CLASS |
443                              USB_RECIP_INTERFACE);
444         req->bRequest = USB_CDC_SEND_ENCAPSULATED_COMMAND;
445         req->wValue = 0;
446         req->wIndex = desc->inum; /* already converted */
447         req->wLength = cpu_to_le16(count);
448         set_bit(WDM_IN_USE, &desc->flags);
449         desc->outbuf = buf;
450 
451         rv = usb_submit_urb(desc->command, GFP_KERNEL);
452         if (rv < 0) {
453                 desc->outbuf = NULL;
454                 clear_bit(WDM_IN_USE, &desc->flags);
455                 dev_err(&desc->intf->dev, "Tx URB error: %d\n", rv);
456                 rv = usb_translate_errors(rv);
457                 goto out_free_mem_pm;
458         } else {
459                 dev_dbg(&desc->intf->dev, "Tx URB has been submitted index=%d\n",
460                         le16_to_cpu(req->wIndex));
461         }
462 
463         usb_autopm_put_interface(desc->intf);
464         mutex_unlock(&desc->wlock);
465 outnl:
466         return rv < 0 ? rv : count;
467 
468 out_free_mem_pm:
469         usb_autopm_put_interface(desc->intf);
470 out_free_mem_lock:
471         mutex_unlock(&desc->wlock);
472 out_free_mem:
473         kfree(buf);
474         return rv;
475 }
476 
477 /*
478  * Submit the read urb if resp_count is non-zero.
479  *
480  * Called with desc->iuspin locked
481  */
482 static int service_outstanding_interrupt(struct wdm_device *desc)
483 {
484         int rv = 0;
485 
486         /* submit read urb only if the device is waiting for it */
487         if (!desc->resp_count || !--desc->resp_count)
488                 goto out;
489 
490         set_bit(WDM_RESPONDING, &desc->flags);
491         spin_unlock_irq(&desc->iuspin);
492         rv = usb_submit_urb(desc->response, GFP_KERNEL);
493         spin_lock_irq(&desc->iuspin);
494         if (rv) {
495                 dev_err(&desc->intf->dev,
496                         "usb_submit_urb failed with result %d\n", rv);
497 
498                 /* make sure the next notification trigger a submit */
499                 clear_bit(WDM_RESPONDING, &desc->flags);
500                 desc->resp_count = 0;
501         }
502 out:
503         return rv;
504 }
505 
506 static ssize_t wdm_read
507 (struct file *file, char __user *buffer, size_t count, loff_t *ppos)
508 {
509         int rv, cntr;
510         int i = 0;
511         struct wdm_device *desc = file->private_data;
512 
513 
514         rv = mutex_lock_interruptible(&desc->rlock); /*concurrent reads */
515         if (rv < 0)
516                 return -ERESTARTSYS;
517 
518         cntr = ACCESS_ONCE(desc->length);
519         if (cntr == 0) {
520                 desc->read = 0;
521 retry:
522                 if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
523                         rv = -ENODEV;
524                         goto err;
525                 }
526                 if (test_bit(WDM_OVERFLOW, &desc->flags)) {
527                         clear_bit(WDM_OVERFLOW, &desc->flags);
528                         rv = -ENOBUFS;
529                         goto err;
530                 }
531                 i++;
532                 if (file->f_flags & O_NONBLOCK) {
533                         if (!test_bit(WDM_READ, &desc->flags)) {
534                                 rv = cntr ? cntr : -EAGAIN;
535                                 goto err;
536                         }
537                         rv = 0;
538                 } else {
539                         rv = wait_event_interruptible(desc->wait,
540                                 test_bit(WDM_READ, &desc->flags));
541                 }
542 
543                 /* may have happened while we slept */
544                 if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
545                         rv = -ENODEV;
546                         goto err;
547                 }
548                 if (test_bit(WDM_RESETTING, &desc->flags)) {
549                         rv = -EIO;
550                         goto err;
551                 }
552                 usb_mark_last_busy(interface_to_usbdev(desc->intf));
553                 if (rv < 0) {
554                         rv = -ERESTARTSYS;
555                         goto err;
556                 }
557 
558                 spin_lock_irq(&desc->iuspin);
559 
560                 if (desc->rerr) { /* read completed, error happened */
561                         rv = usb_translate_errors(desc->rerr);
562                         desc->rerr = 0;
563                         spin_unlock_irq(&desc->iuspin);
564                         goto err;
565                 }
566                 /*
567                  * recheck whether we've lost the race
568                  * against the completion handler
569                  */
570                 if (!test_bit(WDM_READ, &desc->flags)) { /* lost race */
571                         spin_unlock_irq(&desc->iuspin);
572                         goto retry;
573                 }
574 
575                 if (!desc->reslength) { /* zero length read */
576                         dev_dbg(&desc->intf->dev, "zero length - clearing WDM_READ\n");
577                         clear_bit(WDM_READ, &desc->flags);
578                         rv = service_outstanding_interrupt(desc);
579                         spin_unlock_irq(&desc->iuspin);
580                         if (rv < 0)
581                                 goto err;
582                         goto retry;
583                 }
584                 cntr = desc->length;
585                 spin_unlock_irq(&desc->iuspin);
586         }
587 
588         if (cntr > count)
589                 cntr = count;
590         rv = copy_to_user(buffer, desc->ubuf, cntr);
591         if (rv > 0) {
592                 rv = -EFAULT;
593                 goto err;
594         }
595 
596         spin_lock_irq(&desc->iuspin);
597 
598         for (i = 0; i < desc->length - cntr; i++)
599                 desc->ubuf[i] = desc->ubuf[i + cntr];
600 
601         desc->length -= cntr;
602         /* in case we had outstanding data */
603         if (!desc->length) {
604                 clear_bit(WDM_READ, &desc->flags);
605                 service_outstanding_interrupt(desc);
606         }
607         spin_unlock_irq(&desc->iuspin);
608         rv = cntr;
609 
610 err:
611         mutex_unlock(&desc->rlock);
612         return rv;
613 }
614 
615 static int wdm_flush(struct file *file, fl_owner_t id)
616 {
617         struct wdm_device *desc = file->private_data;
618 
619         wait_event(desc->wait, !test_bit(WDM_IN_USE, &desc->flags));
620 
621         /* cannot dereference desc->intf if WDM_DISCONNECTING */
622         if (desc->werr < 0 && !test_bit(WDM_DISCONNECTING, &desc->flags))
623                 dev_err(&desc->intf->dev, "Error in flush path: %d\n",
624                         desc->werr);
625 
626         return usb_translate_errors(desc->werr);
627 }
628 
629 static unsigned int wdm_poll(struct file *file, struct poll_table_struct *wait)
630 {
631         struct wdm_device *desc = file->private_data;
632         unsigned long flags;
633         unsigned int mask = 0;
634 
635         spin_lock_irqsave(&desc->iuspin, flags);
636         if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
637                 mask = POLLHUP | POLLERR;
638                 spin_unlock_irqrestore(&desc->iuspin, flags);
639                 goto desc_out;
640         }
641         if (test_bit(WDM_READ, &desc->flags))
642                 mask = POLLIN | POLLRDNORM;
643         if (desc->rerr || desc->werr)
644                 mask |= POLLERR;
645         if (!test_bit(WDM_IN_USE, &desc->flags))
646                 mask |= POLLOUT | POLLWRNORM;
647         spin_unlock_irqrestore(&desc->iuspin, flags);
648 
649         poll_wait(file, &desc->wait, wait);
650 
651 desc_out:
652         return mask;
653 }
654 
655 static int wdm_open(struct inode *inode, struct file *file)
656 {
657         int minor = iminor(inode);
658         int rv = -ENODEV;
659         struct usb_interface *intf;
660         struct wdm_device *desc;
661 
662         mutex_lock(&wdm_mutex);
663         desc = wdm_find_device_by_minor(minor);
664         if (!desc)
665                 goto out;
666 
667         intf = desc->intf;
668         if (test_bit(WDM_DISCONNECTING, &desc->flags))
669                 goto out;
670         file->private_data = desc;
671 
672         rv = usb_autopm_get_interface(desc->intf);
673         if (rv < 0) {
674                 dev_err(&desc->intf->dev, "Error autopm - %d\n", rv);
675                 goto out;
676         }
677 
678         /* using write lock to protect desc->count */
679         mutex_lock(&desc->wlock);
680         if (!desc->count++) {
681                 desc->werr = 0;
682                 desc->rerr = 0;
683                 rv = usb_submit_urb(desc->validity, GFP_KERNEL);
684                 if (rv < 0) {
685                         desc->count--;
686                         dev_err(&desc->intf->dev,
687                                 "Error submitting int urb - %d\n", rv);
688                         rv = usb_translate_errors(rv);
689                 } else if (test_bit(WDM_DRAIN_ON_OPEN, &desc->flags)) {
690                         /*
691                          * Some devices keep pending messages queued
692                          * without resending notifications.  We must
693                          * flush the message queue before we can
694                          * assume a one-to-one relationship between
695                          * notifications and messages in the queue
696                          */
697                         dev_dbg(&desc->intf->dev, "draining queued data\n");
698                         set_bit(WDM_RESPONDING, &desc->flags);
699                         rv = usb_submit_urb(desc->response, GFP_KERNEL);
700                 }
701         } else {
702                 rv = 0;
703         }
704         mutex_unlock(&desc->wlock);
705         if (desc->count == 1)
706                 desc->manage_power(intf, 1);
707         usb_autopm_put_interface(desc->intf);
708 out:
709         mutex_unlock(&wdm_mutex);
710         return rv;
711 }
712 
713 static int wdm_release(struct inode *inode, struct file *file)
714 {
715         struct wdm_device *desc = file->private_data;
716 
717         mutex_lock(&wdm_mutex);
718 
719         /* using write lock to protect desc->count */
720         mutex_lock(&desc->wlock);
721         desc->count--;
722         mutex_unlock(&desc->wlock);
723 
724         if (!desc->count) {
725                 if (!test_bit(WDM_DISCONNECTING, &desc->flags)) {
726                         dev_dbg(&desc->intf->dev, "wdm_release: cleanup\n");
727                         kill_urbs(desc);
728                         spin_lock_irq(&desc->iuspin);
729                         desc->resp_count = 0;
730                         spin_unlock_irq(&desc->iuspin);
731                         desc->manage_power(desc->intf, 0);
732                 } else {
733                         /* must avoid dev_printk here as desc->intf is invalid */
734                         pr_debug(KBUILD_MODNAME " %s: device gone - cleaning up\n", __func__);
735                         cleanup(desc);
736                 }
737         }
738         mutex_unlock(&wdm_mutex);
739         return 0;
740 }
741 
742 static long wdm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
743 {
744         struct wdm_device *desc = file->private_data;
745         int rv = 0;
746 
747         switch (cmd) {
748         case IOCTL_WDM_MAX_COMMAND:
749                 if (copy_to_user((void __user *)arg, &desc->wMaxCommand, sizeof(desc->wMaxCommand)))
750                         rv = -EFAULT;
751                 break;
752         default:
753                 rv = -ENOTTY;
754         }
755         return rv;
756 }
757 
758 static const struct file_operations wdm_fops = {
759         .owner =        THIS_MODULE,
760         .read =         wdm_read,
761         .write =        wdm_write,
762         .open =         wdm_open,
763         .flush =        wdm_flush,
764         .release =      wdm_release,
765         .poll =         wdm_poll,
766         .unlocked_ioctl = wdm_ioctl,
767         .compat_ioctl = wdm_ioctl,
768         .llseek =       noop_llseek,
769 };
770 
771 static struct usb_class_driver wdm_class = {
772         .name =         "cdc-wdm%d",
773         .fops =         &wdm_fops,
774         .minor_base =   WDM_MINOR_BASE,
775 };
776 
777 /* --- error handling --- */
778 static void wdm_rxwork(struct work_struct *work)
779 {
780         struct wdm_device *desc = container_of(work, struct wdm_device, rxwork);
781         unsigned long flags;
782         int rv = 0;
783         int responding;
784 
785         spin_lock_irqsave(&desc->iuspin, flags);
786         if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
787                 spin_unlock_irqrestore(&desc->iuspin, flags);
788         } else {
789                 responding = test_and_set_bit(WDM_RESPONDING, &desc->flags);
790                 spin_unlock_irqrestore(&desc->iuspin, flags);
791                 if (!responding)
792                         rv = usb_submit_urb(desc->response, GFP_KERNEL);
793                 if (rv < 0 && rv != -EPERM) {
794                         spin_lock_irqsave(&desc->iuspin, flags);
795                         clear_bit(WDM_RESPONDING, &desc->flags);
796                         if (!test_bit(WDM_DISCONNECTING, &desc->flags))
797                                 schedule_work(&desc->rxwork);
798                         spin_unlock_irqrestore(&desc->iuspin, flags);
799                 }
800         }
801 }
802 
803 /* --- hotplug --- */
804 
805 static int wdm_create(struct usb_interface *intf, struct usb_endpoint_descriptor *ep,
806                 u16 bufsize, int (*manage_power)(struct usb_interface *, int),
807                 bool drain_on_open)
808 {
809         int rv = -ENOMEM;
810         struct wdm_device *desc;
811 
812         desc = kzalloc(sizeof(struct wdm_device), GFP_KERNEL);
813         if (!desc)
814                 goto out;
815         INIT_LIST_HEAD(&desc->device_list);
816         mutex_init(&desc->rlock);
817         mutex_init(&desc->wlock);
818         spin_lock_init(&desc->iuspin);
819         init_waitqueue_head(&desc->wait);
820         desc->wMaxCommand = bufsize;
821         /* this will be expanded and needed in hardware endianness */
822         desc->inum = cpu_to_le16((u16)intf->cur_altsetting->desc.bInterfaceNumber);
823         desc->intf = intf;
824         INIT_WORK(&desc->rxwork, wdm_rxwork);
825 
826         rv = -EINVAL;
827         if (!usb_endpoint_is_int_in(ep))
828                 goto err;
829 
830         desc->wMaxPacketSize = usb_endpoint_maxp(ep);
831 
832         desc->orq = kmalloc(sizeof(struct usb_ctrlrequest), GFP_KERNEL);
833         if (!desc->orq)
834                 goto err;
835         desc->irq = kmalloc(sizeof(struct usb_ctrlrequest), GFP_KERNEL);
836         if (!desc->irq)
837                 goto err;
838 
839         desc->validity = usb_alloc_urb(0, GFP_KERNEL);
840         if (!desc->validity)
841                 goto err;
842 
843         desc->response = usb_alloc_urb(0, GFP_KERNEL);
844         if (!desc->response)
845                 goto err;
846 
847         desc->command = usb_alloc_urb(0, GFP_KERNEL);
848         if (!desc->command)
849                 goto err;
850 
851         desc->ubuf = kmalloc(desc->wMaxCommand, GFP_KERNEL);
852         if (!desc->ubuf)
853                 goto err;
854 
855         desc->sbuf = kmalloc(desc->wMaxPacketSize, GFP_KERNEL);
856         if (!desc->sbuf)
857                 goto err;
858 
859         desc->inbuf = kmalloc(desc->wMaxCommand, GFP_KERNEL);
860         if (!desc->inbuf)
861                 goto err;
862 
863         usb_fill_int_urb(
864                 desc->validity,
865                 interface_to_usbdev(intf),
866                 usb_rcvintpipe(interface_to_usbdev(intf), ep->bEndpointAddress),
867                 desc->sbuf,
868                 desc->wMaxPacketSize,
869                 wdm_int_callback,
870                 desc,
871                 ep->bInterval
872         );
873 
874         desc->irq->bRequestType = (USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE);
875         desc->irq->bRequest = USB_CDC_GET_ENCAPSULATED_RESPONSE;
876         desc->irq->wValue = 0;
877         desc->irq->wIndex = desc->inum; /* already converted */
878         desc->irq->wLength = cpu_to_le16(desc->wMaxCommand);
879 
880         usb_fill_control_urb(
881                 desc->response,
882                 interface_to_usbdev(intf),
883                 /* using common endpoint 0 */
884                 usb_rcvctrlpipe(interface_to_usbdev(desc->intf), 0),
885                 (unsigned char *)desc->irq,
886                 desc->inbuf,
887                 desc->wMaxCommand,
888                 wdm_in_callback,
889                 desc
890         );
891 
892         desc->manage_power = manage_power;
893 
894         /*
895          * "drain_on_open" enables a hack to work around a firmware
896          * issue observed on network functions, in particular MBIM
897          * functions.
898          *
899          * Quoting section 7 of the CDC-WMC r1.1 specification:
900          *
901          *  "The firmware shall interpret GetEncapsulatedResponse as a
902          *   request to read response bytes. The firmware shall send
903          *   the next wLength bytes from the response. The firmware
904          *   shall allow the host to retrieve data using any number of
905          *   GetEncapsulatedResponse requests. The firmware shall
906          *   return a zero- length reply if there are no data bytes
907          *   available.
908          *
909          *   The firmware shall send ResponseAvailable notifications
910          *   periodically, using any appropriate algorithm, to inform
911          *   the host that there is data available in the reply
912          *   buffer. The firmware is allowed to send ResponseAvailable
913          *   notifications even if there is no data available, but
914          *   this will obviously reduce overall performance."
915          *
916          * These requirements, although they make equally sense, are
917          * often not implemented by network functions. Some firmwares
918          * will queue data indefinitely, without ever resending a
919          * notification. The result is that the driver and firmware
920          * loses "syncronization" if the driver ever fails to respond
921          * to a single notification, something which easily can happen
922          * on release(). When this happens, the driver will appear to
923          * never receive notifications for the most current data. Each
924          * notification will only cause a single read, which returns
925          * the oldest data in the firmware's queue.
926          *
927          * The "drain_on_open" hack resolves the situation by draining
928          * data from the firmware until none is returned, without a
929          * prior notification.
930          *
931          * This will inevitably race with the firmware, risking that
932          * we read data from the device before handling the associated
933          * notification. To make things worse, some of the devices
934          * needing the hack do not implement the "return zero if no
935          * data is available" requirement either. Instead they return
936          * an error on the subsequent read in this case.  This means
937          * that "winning" the race can cause an unexpected EIO to
938          * userspace.
939          *
940          * "winning" the race is more likely on resume() than on
941          * open(), and the unexpected error is more harmful in the
942          * middle of an open session. The hack is therefore only
943          * applied on open(), and not on resume() where it logically
944          * would be equally necessary. So we define open() as the only
945          * driver <-> device "syncronization point".  Should we happen
946          * to lose a notification after open(), then syncronization
947          * will be lost until release()
948          *
949          * The hack should not be enabled for CDC WDM devices
950          * conforming to the CDC-WMC r1.1 specification.  This is
951          * ensured by setting drain_on_open to false in wdm_probe().
952          */
953         if (drain_on_open)
954                 set_bit(WDM_DRAIN_ON_OPEN, &desc->flags);
955 
956         spin_lock(&wdm_device_list_lock);
957         list_add(&desc->device_list, &wdm_device_list);
958         spin_unlock(&wdm_device_list_lock);
959 
960         rv = usb_register_dev(intf, &wdm_class);
961         if (rv < 0)
962                 goto err;
963         else
964                 dev_info(&intf->dev, "%s: USB WDM device\n", dev_name(intf->usb_dev));
965 out:
966         return rv;
967 err:
968         spin_lock(&wdm_device_list_lock);
969         list_del(&desc->device_list);
970         spin_unlock(&wdm_device_list_lock);
971         cleanup(desc);
972         return rv;
973 }
974 
975 static int wdm_manage_power(struct usb_interface *intf, int on)
976 {
977         /* need autopm_get/put here to ensure the usbcore sees the new value */
978         int rv = usb_autopm_get_interface(intf);
979 
980         intf->needs_remote_wakeup = on;
981         if (!rv)
982                 usb_autopm_put_interface(intf);
983         return 0;
984 }
985 
986 static int wdm_probe(struct usb_interface *intf, const struct usb_device_id *id)
987 {
988         int rv = -EINVAL;
989         struct usb_host_interface *iface;
990         struct usb_endpoint_descriptor *ep;
991         struct usb_cdc_parsed_header hdr;
992         u8 *buffer = intf->altsetting->extra;
993         int buflen = intf->altsetting->extralen;
994         u16 maxcom = WDM_DEFAULT_BUFSIZE;
995 
996         if (!buffer)
997                 goto err;
998 
999         cdc_parse_cdc_header(&hdr, intf, buffer, buflen);
1000 
1001         if (hdr.usb_cdc_dmm_desc)
1002                 maxcom = le16_to_cpu(hdr.usb_cdc_dmm_desc->wMaxCommand);
1003 
1004         iface = intf->cur_altsetting;
1005         if (iface->desc.bNumEndpoints != 1)
1006                 goto err;
1007         ep = &iface->endpoint[0].desc;
1008 
1009         rv = wdm_create(intf, ep, maxcom, &wdm_manage_power, false);
1010 
1011 err:
1012         return rv;
1013 }
1014 
1015 /**
1016  * usb_cdc_wdm_register - register a WDM subdriver
1017  * @intf: usb interface the subdriver will associate with
1018  * @ep: interrupt endpoint to monitor for notifications
1019  * @bufsize: maximum message size to support for read/write
1020  *
1021  * Create WDM usb class character device and associate it with intf
1022  * without binding, allowing another driver to manage the interface.
1023  *
1024  * The subdriver will manage the given interrupt endpoint exclusively
1025  * and will issue control requests referring to the given intf. It
1026  * will otherwise avoid interferring, and in particular not do
1027  * usb_set_intfdata/usb_get_intfdata on intf.
1028  *
1029  * The return value is a pointer to the subdriver's struct usb_driver.
1030  * The registering driver is responsible for calling this subdriver's
1031  * disconnect, suspend, resume, pre_reset and post_reset methods from
1032  * its own.
1033  */
1034 struct usb_driver *usb_cdc_wdm_register(struct usb_interface *intf,
1035                                         struct usb_endpoint_descriptor *ep,
1036                                         int bufsize,
1037                                         int (*manage_power)(struct usb_interface *, int))
1038 {
1039         int rv = -EINVAL;
1040 
1041         rv = wdm_create(intf, ep, bufsize, manage_power, true);
1042         if (rv < 0)
1043                 goto err;
1044 
1045         return &wdm_driver;
1046 err:
1047         return ERR_PTR(rv);
1048 }
1049 EXPORT_SYMBOL(usb_cdc_wdm_register);
1050 
1051 static void wdm_disconnect(struct usb_interface *intf)
1052 {
1053         struct wdm_device *desc;
1054         unsigned long flags;
1055 
1056         usb_deregister_dev(intf, &wdm_class);
1057         desc = wdm_find_device(intf);
1058         mutex_lock(&wdm_mutex);
1059 
1060         /* the spinlock makes sure no new urbs are generated in the callbacks */
1061         spin_lock_irqsave(&desc->iuspin, flags);
1062         set_bit(WDM_DISCONNECTING, &desc->flags);
1063         set_bit(WDM_READ, &desc->flags);
1064         /* to terminate pending flushes */
1065         clear_bit(WDM_IN_USE, &desc->flags);
1066         spin_unlock_irqrestore(&desc->iuspin, flags);
1067         wake_up_all(&desc->wait);
1068         mutex_lock(&desc->rlock);
1069         mutex_lock(&desc->wlock);
1070         kill_urbs(desc);
1071         cancel_work_sync(&desc->rxwork);
1072         mutex_unlock(&desc->wlock);
1073         mutex_unlock(&desc->rlock);
1074 
1075         /* the desc->intf pointer used as list key is now invalid */
1076         spin_lock(&wdm_device_list_lock);
1077         list_del(&desc->device_list);
1078         spin_unlock(&wdm_device_list_lock);
1079 
1080         if (!desc->count)
1081                 cleanup(desc);
1082         else
1083                 dev_dbg(&intf->dev, "%d open files - postponing cleanup\n", desc->count);
1084         mutex_unlock(&wdm_mutex);
1085 }
1086 
1087 #ifdef CONFIG_PM
1088 static int wdm_suspend(struct usb_interface *intf, pm_message_t message)
1089 {
1090         struct wdm_device *desc = wdm_find_device(intf);
1091         int rv = 0;
1092 
1093         dev_dbg(&desc->intf->dev, "wdm%d_suspend\n", intf->minor);
1094 
1095         /* if this is an autosuspend the caller does the locking */
1096         if (!PMSG_IS_AUTO(message)) {
1097                 mutex_lock(&desc->rlock);
1098                 mutex_lock(&desc->wlock);
1099         }
1100         spin_lock_irq(&desc->iuspin);
1101 
1102         if (PMSG_IS_AUTO(message) &&
1103                         (test_bit(WDM_IN_USE, &desc->flags)
1104                         || test_bit(WDM_RESPONDING, &desc->flags))) {
1105                 spin_unlock_irq(&desc->iuspin);
1106                 rv = -EBUSY;
1107         } else {
1108 
1109                 set_bit(WDM_SUSPENDING, &desc->flags);
1110                 spin_unlock_irq(&desc->iuspin);
1111                 /* callback submits work - order is essential */
1112                 kill_urbs(desc);
1113                 cancel_work_sync(&desc->rxwork);
1114         }
1115         if (!PMSG_IS_AUTO(message)) {
1116                 mutex_unlock(&desc->wlock);
1117                 mutex_unlock(&desc->rlock);
1118         }
1119 
1120         return rv;
1121 }
1122 #endif
1123 
1124 static int recover_from_urb_loss(struct wdm_device *desc)
1125 {
1126         int rv = 0;
1127 
1128         if (desc->count) {
1129                 rv = usb_submit_urb(desc->validity, GFP_NOIO);
1130                 if (rv < 0)
1131                         dev_err(&desc->intf->dev,
1132                                 "Error resume submitting int urb - %d\n", rv);
1133         }
1134         return rv;
1135 }
1136 
1137 #ifdef CONFIG_PM
1138 static int wdm_resume(struct usb_interface *intf)
1139 {
1140         struct wdm_device *desc = wdm_find_device(intf);
1141         int rv;
1142 
1143         dev_dbg(&desc->intf->dev, "wdm%d_resume\n", intf->minor);
1144 
1145         clear_bit(WDM_SUSPENDING, &desc->flags);
1146         rv = recover_from_urb_loss(desc);
1147 
1148         return rv;
1149 }
1150 #endif
1151 
1152 static int wdm_pre_reset(struct usb_interface *intf)
1153 {
1154         struct wdm_device *desc = wdm_find_device(intf);
1155 
1156         /*
1157          * we notify everybody using poll of
1158          * an exceptional situation
1159          * must be done before recovery lest a spontaneous
1160          * message from the device is lost
1161          */
1162         spin_lock_irq(&desc->iuspin);
1163         set_bit(WDM_RESETTING, &desc->flags);   /* inform read/write */
1164         set_bit(WDM_READ, &desc->flags);        /* unblock read */
1165         clear_bit(WDM_IN_USE, &desc->flags);    /* unblock write */
1166         desc->rerr = -EINTR;
1167         spin_unlock_irq(&desc->iuspin);
1168         wake_up_all(&desc->wait);
1169         mutex_lock(&desc->rlock);
1170         mutex_lock(&desc->wlock);
1171         kill_urbs(desc);
1172         cancel_work_sync(&desc->rxwork);
1173         return 0;
1174 }
1175 
1176 static int wdm_post_reset(struct usb_interface *intf)
1177 {
1178         struct wdm_device *desc = wdm_find_device(intf);
1179         int rv;
1180 
1181         clear_bit(WDM_OVERFLOW, &desc->flags);
1182         clear_bit(WDM_RESETTING, &desc->flags);
1183         rv = recover_from_urb_loss(desc);
1184         mutex_unlock(&desc->wlock);
1185         mutex_unlock(&desc->rlock);
1186         return 0;
1187 }
1188 
1189 static struct usb_driver wdm_driver = {
1190         .name =         "cdc_wdm",
1191         .probe =        wdm_probe,
1192         .disconnect =   wdm_disconnect,
1193 #ifdef CONFIG_PM
1194         .suspend =      wdm_suspend,
1195         .resume =       wdm_resume,
1196         .reset_resume = wdm_resume,
1197 #endif
1198         .pre_reset =    wdm_pre_reset,
1199         .post_reset =   wdm_post_reset,
1200         .id_table =     wdm_ids,
1201         .supports_autosuspend = 1,
1202         .disable_hub_initiated_lpm = 1,
1203 };
1204 
1205 module_usb_driver(wdm_driver);
1206 
1207 MODULE_AUTHOR(DRIVER_AUTHOR);
1208 MODULE_DESCRIPTION(DRIVER_DESC);
1209 MODULE_LICENSE("GPL");
1210 

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