61522787f39cdd4f2fbfd99d7467be4c62757031
[linux-2.6.git] / drivers / usb / usb-skeleton.c
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 <linux/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 const 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         struct urb              *bulk_in_urb;           /* the urb to read data with */
56         unsigned char           *bulk_in_buffer;        /* the buffer to receive data */
57         size_t                  bulk_in_size;           /* the size of the receive buffer */
58         size_t                  bulk_in_filled;         /* number of bytes in the buffer */
59         size_t                  bulk_in_copied;         /* already copied to user space */
60         __u8                    bulk_in_endpointAddr;   /* the address of the bulk in endpoint */
61         __u8                    bulk_out_endpointAddr;  /* the address of the bulk out endpoint */
62         int                     errors;                 /* the last request tanked */
63         int                     open_count;             /* count the number of openers */
64         bool                    ongoing_read;           /* a read is going on */
65         bool                    processed_urb;          /* indicates we haven't processed the urb */
66         spinlock_t              err_lock;               /* lock for errors */
67         struct kref             kref;
68         struct mutex            io_mutex;               /* synchronize I/O with disconnect */
69         struct completion       bulk_in_completion;     /* to wait for an ongoing read */
70 };
71 #define to_skel_dev(d) container_of(d, struct usb_skel, kref)
72
73 static struct usb_driver skel_driver;
74 static void skel_draw_down(struct usb_skel *dev);
75
76 static void skel_delete(struct kref *kref)
77 {
78         struct usb_skel *dev = to_skel_dev(kref);
79
80         usb_free_urb(dev->bulk_in_urb);
81         usb_put_dev(dev->udev);
82         kfree(dev->bulk_in_buffer);
83         kfree(dev);
84 }
85
86 static int skel_open(struct inode *inode, struct file *file)
87 {
88         struct usb_skel *dev;
89         struct usb_interface *interface;
90         int subminor;
91         int retval = 0;
92
93         subminor = iminor(inode);
94
95         interface = usb_find_interface(&skel_driver, subminor);
96         if (!interface) {
97                 err("%s - error, can't find device for minor %d",
98                      __func__, subminor);
99                 retval = -ENODEV;
100                 goto exit;
101         }
102
103         dev = usb_get_intfdata(interface);
104         if (!dev) {
105                 retval = -ENODEV;
106                 goto exit;
107         }
108
109         /* increment our usage count for the device */
110         kref_get(&dev->kref);
111
112         /* lock the device to allow correctly handling errors
113          * in resumption */
114         mutex_lock(&dev->io_mutex);
115
116         if (!dev->open_count++) {
117                 retval = usb_autopm_get_interface(interface);
118                         if (retval) {
119                                 dev->open_count--;
120                                 mutex_unlock(&dev->io_mutex);
121                                 kref_put(&dev->kref, skel_delete);
122                                 goto exit;
123                         }
124         } /* else { //uncomment this block if you want exclusive open
125                 retval = -EBUSY;
126                 dev->open_count--;
127                 mutex_unlock(&dev->io_mutex);
128                 kref_put(&dev->kref, skel_delete);
129                 goto exit;
130         } */
131         /* prevent the device from being autosuspended */
132
133         /* save our object in the file's private structure */
134         file->private_data = dev;
135         mutex_unlock(&dev->io_mutex);
136
137 exit:
138         return retval;
139 }
140
141 static int skel_release(struct inode *inode, struct file *file)
142 {
143         struct usb_skel *dev;
144
145         dev = (struct usb_skel *)file->private_data;
146         if (dev == NULL)
147                 return -ENODEV;
148
149         /* allow the device to be autosuspended */
150         mutex_lock(&dev->io_mutex);
151         if (!--dev->open_count && dev->interface)
152                 usb_autopm_put_interface(dev->interface);
153         mutex_unlock(&dev->io_mutex);
154
155         /* decrement the count on our device */
156         kref_put(&dev->kref, skel_delete);
157         return 0;
158 }
159
160 static int skel_flush(struct file *file, fl_owner_t id)
161 {
162         struct usb_skel *dev;
163         int res;
164
165         dev = (struct usb_skel *)file->private_data;
166         if (dev == NULL)
167                 return -ENODEV;
168
169         /* wait for io to stop */
170         mutex_lock(&dev->io_mutex);
171         skel_draw_down(dev);
172
173         /* read out errors, leave subsequent opens a clean slate */
174         spin_lock_irq(&dev->err_lock);
175         res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
176         dev->errors = 0;
177         spin_unlock_irq(&dev->err_lock);
178
179         mutex_unlock(&dev->io_mutex);
180
181         return res;
182 }
183
184 static void skel_read_bulk_callback(struct urb *urb)
185 {
186         struct usb_skel *dev;
187
188         dev = urb->context;
189
190         spin_lock(&dev->err_lock);
191         /* sync/async unlink faults aren't errors */
192         if (urb->status) {
193                 if (!(urb->status == -ENOENT ||
194                     urb->status == -ECONNRESET ||
195                     urb->status == -ESHUTDOWN))
196                         err("%s - nonzero write bulk status received: %d",
197                             __func__, urb->status);
198
199                 dev->errors = urb->status;
200         } else {
201                 dev->bulk_in_filled = urb->actual_length;
202         }
203         dev->ongoing_read = 0;
204         spin_unlock(&dev->err_lock);
205
206         complete(&dev->bulk_in_completion);
207 }
208
209 static int skel_do_read_io(struct usb_skel *dev, size_t count)
210 {
211         int rv;
212
213         /* prepare a read */
214         usb_fill_bulk_urb(dev->bulk_in_urb,
215                         dev->udev,
216                         usb_rcvbulkpipe(dev->udev,
217                                 dev->bulk_in_endpointAddr),
218                         dev->bulk_in_buffer,
219                         min(dev->bulk_in_size, count),
220                         skel_read_bulk_callback,
221                         dev);
222         /* tell everybody to leave the URB alone */
223         spin_lock_irq(&dev->err_lock);
224         dev->ongoing_read = 1;
225         spin_unlock_irq(&dev->err_lock);
226
227         /* do it */
228         rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
229         if (rv < 0) {
230                 err("%s - failed submitting read urb, error %d",
231                         __func__, rv);
232                 dev->bulk_in_filled = 0;
233                 rv = (rv == -ENOMEM) ? rv : -EIO;
234                 spin_lock_irq(&dev->err_lock);
235                 dev->ongoing_read = 0;
236                 spin_unlock_irq(&dev->err_lock);
237         }
238
239         return rv;
240 }
241
242 static ssize_t skel_read(struct file *file, char *buffer, size_t count,
243                          loff_t *ppos)
244 {
245         struct usb_skel *dev;
246         int rv;
247         bool ongoing_io;
248
249         dev = (struct usb_skel *)file->private_data;
250
251         /* if we cannot read at all, return EOF */
252         if (!dev->bulk_in_urb || !count)
253                 return 0;
254
255         /* no concurrent readers */
256         rv = mutex_lock_interruptible(&dev->io_mutex);
257         if (rv < 0)
258                 return rv;
259
260         if (!dev->interface) {          /* disconnect() was called */
261                 rv = -ENODEV;
262                 goto exit;
263         }
264
265         /* if IO is under way, we must not touch things */
266 retry:
267         spin_lock_irq(&dev->err_lock);
268         ongoing_io = dev->ongoing_read;
269         spin_unlock_irq(&dev->err_lock);
270
271         if (ongoing_io) {
272                 /* nonblocking IO shall not wait */
273                 if (file->f_flags & O_NONBLOCK) {
274                         rv = -EAGAIN;
275                         goto exit;
276                 }
277                 /*
278                  * IO may take forever
279                  * hence wait in an interruptible state
280                  */
281                 rv = wait_for_completion_interruptible(&dev->bulk_in_completion);
282                 if (rv < 0)
283                         goto exit;
284                 /*
285                  * by waiting we also semiprocessed the urb
286                  * we must finish now
287                  */
288                 dev->bulk_in_copied = 0;
289                 dev->processed_urb = 1;
290         }
291
292         if (!dev->processed_urb) {
293                 /*
294                  * the URB hasn't been processed
295                  * do it now
296                  */
297                 wait_for_completion(&dev->bulk_in_completion);
298                 dev->bulk_in_copied = 0;
299                 dev->processed_urb = 1;
300         }
301
302         /* errors must be reported */
303         rv = dev->errors;
304         if (rv < 0) {
305                 /* any error is reported once */
306                 dev->errors = 0;
307                 /* to preserve notifications about reset */
308                 rv = (rv == -EPIPE) ? rv : -EIO;
309                 /* no data to deliver */
310                 dev->bulk_in_filled = 0;
311                 /* report it */
312                 goto exit;
313         }
314
315         /*
316          * if the buffer is filled we may satisfy the read
317          * else we need to start IO
318          */
319
320         if (dev->bulk_in_filled) {
321                 /* we had read data */
322                 size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
323                 size_t chunk = min(available, count);
324
325                 if (!available) {
326                         /*
327                          * all data has been used
328                          * actual IO needs to be done
329                          */
330                         rv = skel_do_read_io(dev, count);
331                         if (rv < 0)
332                                 goto exit;
333                         else
334                                 goto retry;
335                 }
336                 /*
337                  * data is available
338                  * chunk tells us how much shall be copied
339                  */
340
341                 if (copy_to_user(buffer,
342                                  dev->bulk_in_buffer + dev->bulk_in_copied,
343                                  chunk))
344                         rv = -EFAULT;
345                 else
346                         rv = chunk;
347
348                 dev->bulk_in_copied += chunk;
349
350                 /*
351                  * if we are asked for more than we have,
352                  * we start IO but don't wait
353                  */
354                 if (available < count)
355                         skel_do_read_io(dev, count - chunk);
356         } else {
357                 /* no data in the buffer */
358                 rv = skel_do_read_io(dev, count);
359                 if (rv < 0)
360                         goto exit;
361                 else if (!(file->f_flags & O_NONBLOCK))
362                         goto retry;
363                 rv = -EAGAIN;
364         }
365 exit:
366         mutex_unlock(&dev->io_mutex);
367         return rv;
368 }
369
370 static void skel_write_bulk_callback(struct urb *urb)
371 {
372         struct usb_skel *dev;
373
374         dev = urb->context;
375
376         /* sync/async unlink faults aren't errors */
377         if (urb->status) {
378                 if (!(urb->status == -ENOENT ||
379                     urb->status == -ECONNRESET ||
380                     urb->status == -ESHUTDOWN))
381                         err("%s - nonzero write bulk status received: %d",
382                             __func__, urb->status);
383
384                 spin_lock(&dev->err_lock);
385                 dev->errors = urb->status;
386                 spin_unlock(&dev->err_lock);
387         }
388
389         /* free up our allocated buffer */
390         usb_buffer_free(urb->dev, urb->transfer_buffer_length,
391                         urb->transfer_buffer, urb->transfer_dma);
392         up(&dev->limit_sem);
393 }
394
395 static ssize_t skel_write(struct file *file, const char *user_buffer,
396                           size_t count, loff_t *ppos)
397 {
398         struct usb_skel *dev;
399         int retval = 0;
400         struct urb *urb = NULL;
401         char *buf = NULL;
402         size_t writesize = min(count, (size_t)MAX_TRANSFER);
403
404         dev = (struct usb_skel *)file->private_data;
405
406         /* verify that we actually have some data to write */
407         if (count == 0)
408                 goto exit;
409
410         /*
411          * limit the number of URBs in flight to stop a user from using up all
412          * RAM
413          */
414         if (!(file->f_flags & O_NONBLOCK)) {
415                 if (down_interruptible(&dev->limit_sem)) {
416                         retval = -ERESTARTSYS;
417                         goto exit;
418                 }
419         } else {
420                 if (down_trylock(&dev->limit_sem)) {
421                         retval = -EAGAIN;
422                         goto exit;
423                 }
424         }
425
426         spin_lock_irq(&dev->err_lock);
427         retval = dev->errors;
428         if (retval < 0) {
429                 /* any error is reported once */
430                 dev->errors = 0;
431                 /* to preserve notifications about reset */
432                 retval = (retval == -EPIPE) ? retval : -EIO;
433         }
434         spin_unlock_irq(&dev->err_lock);
435         if (retval < 0)
436                 goto error;
437
438         /* create a urb, and a buffer for it, and copy the data to the urb */
439         urb = usb_alloc_urb(0, GFP_KERNEL);
440         if (!urb) {
441                 retval = -ENOMEM;
442                 goto error;
443         }
444
445         buf = usb_buffer_alloc(dev->udev, writesize, GFP_KERNEL,
446                                &urb->transfer_dma);
447         if (!buf) {
448                 retval = -ENOMEM;
449                 goto error;
450         }
451
452         if (copy_from_user(buf, user_buffer, writesize)) {
453                 retval = -EFAULT;
454                 goto error;
455         }
456
457         /* this lock makes sure we don't submit URBs to gone devices */
458         mutex_lock(&dev->io_mutex);
459         if (!dev->interface) {          /* disconnect() was called */
460                 mutex_unlock(&dev->io_mutex);
461                 retval = -ENODEV;
462                 goto error;
463         }
464
465         /* initialize the urb properly */
466         usb_fill_bulk_urb(urb, dev->udev,
467                           usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
468                           buf, writesize, skel_write_bulk_callback, dev);
469         urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
470         usb_anchor_urb(urb, &dev->submitted);
471
472         /* send the data out the bulk port */
473         retval = usb_submit_urb(urb, GFP_KERNEL);
474         mutex_unlock(&dev->io_mutex);
475         if (retval) {
476                 err("%s - failed submitting write urb, error %d", __func__,
477                     retval);
478                 goto error_unanchor;
479         }
480
481         /*
482          * release our reference to this urb, the USB core will eventually free
483          * it entirely
484          */
485         usb_free_urb(urb);
486
487
488         return writesize;
489
490 error_unanchor:
491         usb_unanchor_urb(urb);
492 error:
493         if (urb) {
494                 usb_buffer_free(dev->udev, writesize, buf, urb->transfer_dma);
495                 usb_free_urb(urb);
496         }
497         up(&dev->limit_sem);
498
499 exit:
500         return retval;
501 }
502
503 static const struct file_operations skel_fops = {
504         .owner =        THIS_MODULE,
505         .read =         skel_read,
506         .write =        skel_write,
507         .open =         skel_open,
508         .release =      skel_release,
509         .flush =        skel_flush,
510 };
511
512 /*
513  * usb class driver info in order to get a minor number from the usb core,
514  * and to have the device registered with the driver core
515  */
516 static struct usb_class_driver skel_class = {
517         .name =         "skel%d",
518         .fops =         &skel_fops,
519         .minor_base =   USB_SKEL_MINOR_BASE,
520 };
521
522 static int skel_probe(struct usb_interface *interface,
523                       const struct usb_device_id *id)
524 {
525         struct usb_skel *dev;
526         struct usb_host_interface *iface_desc;
527         struct usb_endpoint_descriptor *endpoint;
528         size_t buffer_size;
529         int i;
530         int retval = -ENOMEM;
531
532         /* allocate memory for our device state and initialize it */
533         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
534         if (!dev) {
535                 err("Out of memory");
536                 goto error;
537         }
538         kref_init(&dev->kref);
539         sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
540         mutex_init(&dev->io_mutex);
541         spin_lock_init(&dev->err_lock);
542         init_usb_anchor(&dev->submitted);
543         init_completion(&dev->bulk_in_completion);
544
545         dev->udev = usb_get_dev(interface_to_usbdev(interface));
546         dev->interface = interface;
547
548         /* set up the endpoint information */
549         /* use only the first bulk-in and bulk-out endpoints */
550         iface_desc = interface->cur_altsetting;
551         for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
552                 endpoint = &iface_desc->endpoint[i].desc;
553
554                 if (!dev->bulk_in_endpointAddr &&
555                     usb_endpoint_is_bulk_in(endpoint)) {
556                         /* we found a bulk in endpoint */
557                         buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
558                         dev->bulk_in_size = buffer_size;
559                         dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
560                         dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
561                         if (!dev->bulk_in_buffer) {
562                                 err("Could not allocate bulk_in_buffer");
563                                 goto error;
564                         }
565                         dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
566                         if (!dev->bulk_in_urb) {
567                                 err("Could not allocate bulk_in_urb");
568                                 goto error;
569                         }
570                 }
571
572                 if (!dev->bulk_out_endpointAddr &&
573                     usb_endpoint_is_bulk_out(endpoint)) {
574                         /* we found a bulk out endpoint */
575                         dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
576                 }
577         }
578         if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
579                 err("Could not find both bulk-in and bulk-out endpoints");
580                 goto error;
581         }
582
583         /* save our data pointer in this interface device */
584         usb_set_intfdata(interface, dev);
585
586         /* we can register the device now, as it is ready */
587         retval = usb_register_dev(interface, &skel_class);
588         if (retval) {
589                 /* something prevented us from registering this driver */
590                 err("Not able to get a minor for this device.");
591                 usb_set_intfdata(interface, NULL);
592                 goto error;
593         }
594
595         /* let the user know what node this device is now attached to */
596         dev_info(&interface->dev,
597                  "USB Skeleton device now attached to USBSkel-%d",
598                  interface->minor);
599         return 0;
600
601 error:
602         if (dev)
603                 /* this frees allocated memory */
604                 kref_put(&dev->kref, skel_delete);
605         return retval;
606 }
607
608 static void skel_disconnect(struct usb_interface *interface)
609 {
610         struct usb_skel *dev;
611         int minor = interface->minor;
612
613         dev = usb_get_intfdata(interface);
614         usb_set_intfdata(interface, NULL);
615
616         /* give back our minor */
617         usb_deregister_dev(interface, &skel_class);
618
619         /* prevent more I/O from starting */
620         mutex_lock(&dev->io_mutex);
621         dev->interface = NULL;
622         mutex_unlock(&dev->io_mutex);
623
624         usb_kill_anchored_urbs(&dev->submitted);
625
626         /* decrement our usage count */
627         kref_put(&dev->kref, skel_delete);
628
629         dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
630 }
631
632 static void skel_draw_down(struct usb_skel *dev)
633 {
634         int time;
635
636         time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
637         if (!time)
638                 usb_kill_anchored_urbs(&dev->submitted);
639         usb_kill_urb(dev->bulk_in_urb);
640 }
641
642 static int skel_suspend(struct usb_interface *intf, pm_message_t message)
643 {
644         struct usb_skel *dev = usb_get_intfdata(intf);
645
646         if (!dev)
647                 return 0;
648         skel_draw_down(dev);
649         return 0;
650 }
651
652 static int skel_resume(struct usb_interface *intf)
653 {
654         return 0;
655 }
656
657 static int skel_pre_reset(struct usb_interface *intf)
658 {
659         struct usb_skel *dev = usb_get_intfdata(intf);
660
661         mutex_lock(&dev->io_mutex);
662         skel_draw_down(dev);
663
664         return 0;
665 }
666
667 static int skel_post_reset(struct usb_interface *intf)
668 {
669         struct usb_skel *dev = usb_get_intfdata(intf);
670
671         /* we are sure no URBs are active - no locking needed */
672         dev->errors = -EPIPE;
673         mutex_unlock(&dev->io_mutex);
674
675         return 0;
676 }
677
678 static struct usb_driver skel_driver = {
679         .name =         "skeleton",
680         .probe =        skel_probe,
681         .disconnect =   skel_disconnect,
682         .suspend =      skel_suspend,
683         .resume =       skel_resume,
684         .pre_reset =    skel_pre_reset,
685         .post_reset =   skel_post_reset,
686         .id_table =     skel_table,
687         .supports_autosuspend = 1,
688 };
689
690 static int __init usb_skel_init(void)
691 {
692         int result;
693
694         /* register this driver with the USB subsystem */
695         result = usb_register(&skel_driver);
696         if (result)
697                 err("usb_register failed. Error number %d", result);
698
699         return result;
700 }
701
702 static void __exit usb_skel_exit(void)
703 {
704         /* deregister this driver with the USB subsystem */
705         usb_deregister(&skel_driver);
706 }
707
708 module_init(usb_skel_init);
709 module_exit(usb_skel_exit);
710
711 MODULE_LICENSE("GPL");