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