Merge branch 'remotes/lorenzo/pci/misc'
[linux-2.6-microblaze.git] / drivers / usb / usb-skeleton.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * USB Skeleton driver - 2.2
4  *
5  * Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com)
6  *
7  * This driver is based on the 2.6.3 version of drivers/usb/usb-skeleton.c
8  * but has been rewritten to be easier to read and use.
9  */
10
11 #include <linux/kernel.h>
12 #include <linux/errno.h>
13 #include <linux/slab.h>
14 #include <linux/module.h>
15 #include <linux/kref.h>
16 #include <linux/uaccess.h>
17 #include <linux/usb.h>
18 #include <linux/mutex.h>
19
20
21 /* Define these values to match your devices */
22 #define USB_SKEL_VENDOR_ID      0xfff0
23 #define USB_SKEL_PRODUCT_ID     0xfff0
24
25 /* table of devices that work with this driver */
26 static const struct usb_device_id skel_table[] = {
27         { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
28         { }                                     /* Terminating entry */
29 };
30 MODULE_DEVICE_TABLE(usb, skel_table);
31
32
33 /* Get a minor range for your devices from the usb maintainer */
34 #define USB_SKEL_MINOR_BASE     192
35
36 /* our private defines. if this grows any larger, use your own .h file */
37 #define MAX_TRANSFER            (PAGE_SIZE - 512)
38 /*
39  * MAX_TRANSFER is chosen so that the VM is not stressed by
40  * allocations > PAGE_SIZE and the number of packets in a page
41  * is an integer 512 is the largest possible packet on EHCI
42  */
43 #define WRITES_IN_FLIGHT        8
44 /* arbitrarily chosen */
45
46 /* Structure to hold all of our device specific stuff */
47 struct usb_skel {
48         struct usb_device       *udev;                  /* the usb device for this device */
49         struct usb_interface    *interface;             /* the interface for this device */
50         struct semaphore        limit_sem;              /* limiting the number of writes in progress */
51         struct usb_anchor       submitted;              /* in case we need to retract our submissions */
52         struct urb              *bulk_in_urb;           /* the urb to read data with */
53         unsigned char           *bulk_in_buffer;        /* the buffer to receive data */
54         size_t                  bulk_in_size;           /* the size of the receive buffer */
55         size_t                  bulk_in_filled;         /* number of bytes in the buffer */
56         size_t                  bulk_in_copied;         /* already copied to user space */
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         bool                    ongoing_read;           /* a read is going on */
61         spinlock_t              err_lock;               /* lock for errors */
62         struct kref             kref;
63         struct mutex            io_mutex;               /* synchronize I/O with disconnect */
64         unsigned long           disconnected:1;
65         wait_queue_head_t       bulk_in_wait;           /* to wait for an ongoing read */
66 };
67 #define to_skel_dev(d) container_of(d, struct usb_skel, kref)
68
69 static struct usb_driver skel_driver;
70 static void skel_draw_down(struct usb_skel *dev);
71
72 static void skel_delete(struct kref *kref)
73 {
74         struct usb_skel *dev = to_skel_dev(kref);
75
76         usb_free_urb(dev->bulk_in_urb);
77         usb_put_intf(dev->interface);
78         usb_put_dev(dev->udev);
79         kfree(dev->bulk_in_buffer);
80         kfree(dev);
81 }
82
83 static int skel_open(struct inode *inode, struct file *file)
84 {
85         struct usb_skel *dev;
86         struct usb_interface *interface;
87         int subminor;
88         int retval = 0;
89
90         subminor = iminor(inode);
91
92         interface = usb_find_interface(&skel_driver, subminor);
93         if (!interface) {
94                 pr_err("%s - error, can't find device for minor %d\n",
95                         __func__, subminor);
96                 retval = -ENODEV;
97                 goto exit;
98         }
99
100         dev = usb_get_intfdata(interface);
101         if (!dev) {
102                 retval = -ENODEV;
103                 goto exit;
104         }
105
106         retval = usb_autopm_get_interface(interface);
107         if (retval)
108                 goto exit;
109
110         /* increment our usage count for the device */
111         kref_get(&dev->kref);
112
113         /* save our object in the file's private structure */
114         file->private_data = dev;
115
116 exit:
117         return retval;
118 }
119
120 static int skel_release(struct inode *inode, struct file *file)
121 {
122         struct usb_skel *dev;
123
124         dev = file->private_data;
125         if (dev == NULL)
126                 return -ENODEV;
127
128         /* allow the device to be autosuspended */
129         usb_autopm_put_interface(dev->interface);
130
131         /* decrement the count on our device */
132         kref_put(&dev->kref, skel_delete);
133         return 0;
134 }
135
136 static int skel_flush(struct file *file, fl_owner_t id)
137 {
138         struct usb_skel *dev;
139         int res;
140
141         dev = file->private_data;
142         if (dev == NULL)
143                 return -ENODEV;
144
145         /* wait for io to stop */
146         mutex_lock(&dev->io_mutex);
147         skel_draw_down(dev);
148
149         /* read out errors, leave subsequent opens a clean slate */
150         spin_lock_irq(&dev->err_lock);
151         res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
152         dev->errors = 0;
153         spin_unlock_irq(&dev->err_lock);
154
155         mutex_unlock(&dev->io_mutex);
156
157         return res;
158 }
159
160 static void skel_read_bulk_callback(struct urb *urb)
161 {
162         struct usb_skel *dev;
163         unsigned long flags;
164
165         dev = urb->context;
166
167         spin_lock_irqsave(&dev->err_lock, flags);
168         /* sync/async unlink faults aren't errors */
169         if (urb->status) {
170                 if (!(urb->status == -ENOENT ||
171                     urb->status == -ECONNRESET ||
172                     urb->status == -ESHUTDOWN))
173                         dev_err(&dev->interface->dev,
174                                 "%s - nonzero write bulk status received: %d\n",
175                                 __func__, urb->status);
176
177                 dev->errors = urb->status;
178         } else {
179                 dev->bulk_in_filled = urb->actual_length;
180         }
181         dev->ongoing_read = 0;
182         spin_unlock_irqrestore(&dev->err_lock, flags);
183
184         wake_up_interruptible(&dev->bulk_in_wait);
185 }
186
187 static int skel_do_read_io(struct usb_skel *dev, size_t count)
188 {
189         int rv;
190
191         /* prepare a read */
192         usb_fill_bulk_urb(dev->bulk_in_urb,
193                         dev->udev,
194                         usb_rcvbulkpipe(dev->udev,
195                                 dev->bulk_in_endpointAddr),
196                         dev->bulk_in_buffer,
197                         min(dev->bulk_in_size, count),
198                         skel_read_bulk_callback,
199                         dev);
200         /* tell everybody to leave the URB alone */
201         spin_lock_irq(&dev->err_lock);
202         dev->ongoing_read = 1;
203         spin_unlock_irq(&dev->err_lock);
204
205         /* submit bulk in urb, which means no data to deliver */
206         dev->bulk_in_filled = 0;
207         dev->bulk_in_copied = 0;
208
209         /* do it */
210         rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
211         if (rv < 0) {
212                 dev_err(&dev->interface->dev,
213                         "%s - failed submitting read urb, error %d\n",
214                         __func__, rv);
215                 rv = (rv == -ENOMEM) ? rv : -EIO;
216                 spin_lock_irq(&dev->err_lock);
217                 dev->ongoing_read = 0;
218                 spin_unlock_irq(&dev->err_lock);
219         }
220
221         return rv;
222 }
223
224 static ssize_t skel_read(struct file *file, char *buffer, size_t count,
225                          loff_t *ppos)
226 {
227         struct usb_skel *dev;
228         int rv;
229         bool ongoing_io;
230
231         dev = file->private_data;
232
233         if (!count)
234                 return 0;
235
236         /* no concurrent readers */
237         rv = mutex_lock_interruptible(&dev->io_mutex);
238         if (rv < 0)
239                 return rv;
240
241         if (dev->disconnected) {                /* disconnect() was called */
242                 rv = -ENODEV;
243                 goto exit;
244         }
245
246         /* if IO is under way, we must not touch things */
247 retry:
248         spin_lock_irq(&dev->err_lock);
249         ongoing_io = dev->ongoing_read;
250         spin_unlock_irq(&dev->err_lock);
251
252         if (ongoing_io) {
253                 /* nonblocking IO shall not wait */
254                 if (file->f_flags & O_NONBLOCK) {
255                         rv = -EAGAIN;
256                         goto exit;
257                 }
258                 /*
259                  * IO may take forever
260                  * hence wait in an interruptible state
261                  */
262                 rv = wait_event_interruptible(dev->bulk_in_wait, (!dev->ongoing_read));
263                 if (rv < 0)
264                         goto exit;
265         }
266
267         /* errors must be reported */
268         rv = dev->errors;
269         if (rv < 0) {
270                 /* any error is reported once */
271                 dev->errors = 0;
272                 /* to preserve notifications about reset */
273                 rv = (rv == -EPIPE) ? rv : -EIO;
274                 /* report it */
275                 goto exit;
276         }
277
278         /*
279          * if the buffer is filled we may satisfy the read
280          * else we need to start IO
281          */
282
283         if (dev->bulk_in_filled) {
284                 /* we had read data */
285                 size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
286                 size_t chunk = min(available, count);
287
288                 if (!available) {
289                         /*
290                          * all data has been used
291                          * actual IO needs to be done
292                          */
293                         rv = skel_do_read_io(dev, count);
294                         if (rv < 0)
295                                 goto exit;
296                         else
297                                 goto retry;
298                 }
299                 /*
300                  * data is available
301                  * chunk tells us how much shall be copied
302                  */
303
304                 if (copy_to_user(buffer,
305                                  dev->bulk_in_buffer + dev->bulk_in_copied,
306                                  chunk))
307                         rv = -EFAULT;
308                 else
309                         rv = chunk;
310
311                 dev->bulk_in_copied += chunk;
312
313                 /*
314                  * if we are asked for more than we have,
315                  * we start IO but don't wait
316                  */
317                 if (available < count)
318                         skel_do_read_io(dev, count - chunk);
319         } else {
320                 /* no data in the buffer */
321                 rv = skel_do_read_io(dev, count);
322                 if (rv < 0)
323                         goto exit;
324                 else
325                         goto retry;
326         }
327 exit:
328         mutex_unlock(&dev->io_mutex);
329         return rv;
330 }
331
332 static void skel_write_bulk_callback(struct urb *urb)
333 {
334         struct usb_skel *dev;
335         unsigned long flags;
336
337         dev = urb->context;
338
339         /* sync/async unlink faults aren't errors */
340         if (urb->status) {
341                 if (!(urb->status == -ENOENT ||
342                     urb->status == -ECONNRESET ||
343                     urb->status == -ESHUTDOWN))
344                         dev_err(&dev->interface->dev,
345                                 "%s - nonzero write bulk status received: %d\n",
346                                 __func__, urb->status);
347
348                 spin_lock_irqsave(&dev->err_lock, flags);
349                 dev->errors = urb->status;
350                 spin_unlock_irqrestore(&dev->err_lock, flags);
351         }
352
353         /* free up our allocated buffer */
354         usb_free_coherent(urb->dev, urb->transfer_buffer_length,
355                           urb->transfer_buffer, urb->transfer_dma);
356         up(&dev->limit_sem);
357 }
358
359 static ssize_t skel_write(struct file *file, const char *user_buffer,
360                           size_t count, loff_t *ppos)
361 {
362         struct usb_skel *dev;
363         int retval = 0;
364         struct urb *urb = NULL;
365         char *buf = NULL;
366         size_t writesize = min(count, (size_t)MAX_TRANSFER);
367
368         dev = file->private_data;
369
370         /* verify that we actually have some data to write */
371         if (count == 0)
372                 goto exit;
373
374         /*
375          * limit the number of URBs in flight to stop a user from using up all
376          * RAM
377          */
378         if (!(file->f_flags & O_NONBLOCK)) {
379                 if (down_interruptible(&dev->limit_sem)) {
380                         retval = -ERESTARTSYS;
381                         goto exit;
382                 }
383         } else {
384                 if (down_trylock(&dev->limit_sem)) {
385                         retval = -EAGAIN;
386                         goto exit;
387                 }
388         }
389
390         spin_lock_irq(&dev->err_lock);
391         retval = dev->errors;
392         if (retval < 0) {
393                 /* any error is reported once */
394                 dev->errors = 0;
395                 /* to preserve notifications about reset */
396                 retval = (retval == -EPIPE) ? retval : -EIO;
397         }
398         spin_unlock_irq(&dev->err_lock);
399         if (retval < 0)
400                 goto error;
401
402         /* create a urb, and a buffer for it, and copy the data to the urb */
403         urb = usb_alloc_urb(0, GFP_KERNEL);
404         if (!urb) {
405                 retval = -ENOMEM;
406                 goto error;
407         }
408
409         buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
410                                  &urb->transfer_dma);
411         if (!buf) {
412                 retval = -ENOMEM;
413                 goto error;
414         }
415
416         if (copy_from_user(buf, user_buffer, writesize)) {
417                 retval = -EFAULT;
418                 goto error;
419         }
420
421         /* this lock makes sure we don't submit URBs to gone devices */
422         mutex_lock(&dev->io_mutex);
423         if (dev->disconnected) {                /* disconnect() was called */
424                 mutex_unlock(&dev->io_mutex);
425                 retval = -ENODEV;
426                 goto error;
427         }
428
429         /* initialize the urb properly */
430         usb_fill_bulk_urb(urb, dev->udev,
431                           usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
432                           buf, writesize, skel_write_bulk_callback, dev);
433         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
434         usb_anchor_urb(urb, &dev->submitted);
435
436         /* send the data out the bulk port */
437         retval = usb_submit_urb(urb, GFP_KERNEL);
438         mutex_unlock(&dev->io_mutex);
439         if (retval) {
440                 dev_err(&dev->interface->dev,
441                         "%s - failed submitting write urb, error %d\n",
442                         __func__, retval);
443                 goto error_unanchor;
444         }
445
446         /*
447          * release our reference to this urb, the USB core will eventually free
448          * it entirely
449          */
450         usb_free_urb(urb);
451
452
453         return writesize;
454
455 error_unanchor:
456         usb_unanchor_urb(urb);
457 error:
458         if (urb) {
459                 usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
460                 usb_free_urb(urb);
461         }
462         up(&dev->limit_sem);
463
464 exit:
465         return retval;
466 }
467
468 static const struct file_operations skel_fops = {
469         .owner =        THIS_MODULE,
470         .read =         skel_read,
471         .write =        skel_write,
472         .open =         skel_open,
473         .release =      skel_release,
474         .flush =        skel_flush,
475         .llseek =       noop_llseek,
476 };
477
478 /*
479  * usb class driver info in order to get a minor number from the usb core,
480  * and to have the device registered with the driver core
481  */
482 static struct usb_class_driver skel_class = {
483         .name =         "skel%d",
484         .fops =         &skel_fops,
485         .minor_base =   USB_SKEL_MINOR_BASE,
486 };
487
488 static int skel_probe(struct usb_interface *interface,
489                       const struct usb_device_id *id)
490 {
491         struct usb_skel *dev;
492         struct usb_endpoint_descriptor *bulk_in, *bulk_out;
493         int retval;
494
495         /* allocate memory for our device state and initialize it */
496         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
497         if (!dev)
498                 return -ENOMEM;
499
500         kref_init(&dev->kref);
501         sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
502         mutex_init(&dev->io_mutex);
503         spin_lock_init(&dev->err_lock);
504         init_usb_anchor(&dev->submitted);
505         init_waitqueue_head(&dev->bulk_in_wait);
506
507         dev->udev = usb_get_dev(interface_to_usbdev(interface));
508         dev->interface = usb_get_intf(interface);
509
510         /* set up the endpoint information */
511         /* use only the first bulk-in and bulk-out endpoints */
512         retval = usb_find_common_endpoints(interface->cur_altsetting,
513                         &bulk_in, &bulk_out, NULL, NULL);
514         if (retval) {
515                 dev_err(&interface->dev,
516                         "Could not find both bulk-in and bulk-out endpoints\n");
517                 goto error;
518         }
519
520         dev->bulk_in_size = usb_endpoint_maxp(bulk_in);
521         dev->bulk_in_endpointAddr = bulk_in->bEndpointAddress;
522         dev->bulk_in_buffer = kmalloc(dev->bulk_in_size, GFP_KERNEL);
523         if (!dev->bulk_in_buffer) {
524                 retval = -ENOMEM;
525                 goto error;
526         }
527         dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
528         if (!dev->bulk_in_urb) {
529                 retval = -ENOMEM;
530                 goto error;
531         }
532
533         dev->bulk_out_endpointAddr = bulk_out->bEndpointAddress;
534
535         /* save our data pointer in this interface device */
536         usb_set_intfdata(interface, dev);
537
538         /* we can register the device now, as it is ready */
539         retval = usb_register_dev(interface, &skel_class);
540         if (retval) {
541                 /* something prevented us from registering this driver */
542                 dev_err(&interface->dev,
543                         "Not able to get a minor for this device.\n");
544                 usb_set_intfdata(interface, NULL);
545                 goto error;
546         }
547
548         /* let the user know what node this device is now attached to */
549         dev_info(&interface->dev,
550                  "USB Skeleton device now attached to USBSkel-%d",
551                  interface->minor);
552         return 0;
553
554 error:
555         /* this frees allocated memory */
556         kref_put(&dev->kref, skel_delete);
557
558         return retval;
559 }
560
561 static void skel_disconnect(struct usb_interface *interface)
562 {
563         struct usb_skel *dev;
564         int minor = interface->minor;
565
566         dev = usb_get_intfdata(interface);
567         usb_set_intfdata(interface, NULL);
568
569         /* give back our minor */
570         usb_deregister_dev(interface, &skel_class);
571
572         /* prevent more I/O from starting */
573         mutex_lock(&dev->io_mutex);
574         dev->disconnected = 1;
575         mutex_unlock(&dev->io_mutex);
576
577         usb_kill_urb(dev->bulk_in_urb);
578         usb_kill_anchored_urbs(&dev->submitted);
579
580         /* decrement our usage count */
581         kref_put(&dev->kref, skel_delete);
582
583         dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
584 }
585
586 static void skel_draw_down(struct usb_skel *dev)
587 {
588         int time;
589
590         time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
591         if (!time)
592                 usb_kill_anchored_urbs(&dev->submitted);
593         usb_kill_urb(dev->bulk_in_urb);
594 }
595
596 static int skel_suspend(struct usb_interface *intf, pm_message_t message)
597 {
598         struct usb_skel *dev = usb_get_intfdata(intf);
599
600         if (!dev)
601                 return 0;
602         skel_draw_down(dev);
603         return 0;
604 }
605
606 static int skel_resume(struct usb_interface *intf)
607 {
608         return 0;
609 }
610
611 static int skel_pre_reset(struct usb_interface *intf)
612 {
613         struct usb_skel *dev = usb_get_intfdata(intf);
614
615         mutex_lock(&dev->io_mutex);
616         skel_draw_down(dev);
617
618         return 0;
619 }
620
621 static int skel_post_reset(struct usb_interface *intf)
622 {
623         struct usb_skel *dev = usb_get_intfdata(intf);
624
625         /* we are sure no URBs are active - no locking needed */
626         dev->errors = -EPIPE;
627         mutex_unlock(&dev->io_mutex);
628
629         return 0;
630 }
631
632 static struct usb_driver skel_driver = {
633         .name =         "skeleton",
634         .probe =        skel_probe,
635         .disconnect =   skel_disconnect,
636         .suspend =      skel_suspend,
637         .resume =       skel_resume,
638         .pre_reset =    skel_pre_reset,
639         .post_reset =   skel_post_reset,
640         .id_table =     skel_table,
641         .supports_autosuspend = 1,
642 };
643
644 module_usb_driver(skel_driver);
645
646 MODULE_LICENSE("GPL v2");