2 * USB Skeleton driver - 2.2
4 * Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com)
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.
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.
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>
26 /* Define these values to match your devices */
27 #define USB_SKEL_VENDOR_ID 0xfff0
28 #define USB_SKEL_PRODUCT_ID 0xfff0
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 */
35 MODULE_DEVICE_TABLE(usb
, skel_table
);
38 /* Get a minor range for your devices from the usb maintainer */
39 #define USB_SKEL_MINOR_BASE 192
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 */
49 /* Structure to hold all of our device specific stuff */
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 */
67 struct mutex io_mutex
; /* synchronize I/O with disconnect */
68 struct completion bulk_in_completion
; /* to wait for an ongoing read */
70 #define to_skel_dev(d) container_of(d, struct usb_skel, kref)
72 static struct usb_driver skel_driver
;
73 static void skel_draw_down(struct usb_skel
*dev
);
75 static void skel_delete(struct kref
*kref
)
77 struct usb_skel
*dev
= to_skel_dev(kref
);
79 usb_free_urb(dev
->bulk_in_urb
);
80 usb_put_dev(dev
->udev
);
81 kfree(dev
->bulk_in_buffer
);
85 static int skel_open(struct inode
*inode
, struct file
*file
)
88 struct usb_interface
*interface
;
92 subminor
= iminor(inode
);
94 interface
= usb_find_interface(&skel_driver
, subminor
);
96 pr_err("%s - error, can't find device for minor %d\n",
102 dev
= usb_get_intfdata(interface
);
108 retval
= usb_autopm_get_interface(interface
);
112 /* increment our usage count for the device */
113 kref_get(&dev
->kref
);
115 /* save our object in the file's private structure */
116 file
->private_data
= dev
;
122 static int skel_release(struct inode
*inode
, struct file
*file
)
124 struct usb_skel
*dev
;
126 dev
= file
->private_data
;
130 /* allow the device to be autosuspended */
131 mutex_lock(&dev
->io_mutex
);
133 usb_autopm_put_interface(dev
->interface
);
134 mutex_unlock(&dev
->io_mutex
);
136 /* decrement the count on our device */
137 kref_put(&dev
->kref
, skel_delete
);
141 static int skel_flush(struct file
*file
, fl_owner_t id
)
143 struct usb_skel
*dev
;
146 dev
= file
->private_data
;
150 /* wait for io to stop */
151 mutex_lock(&dev
->io_mutex
);
154 /* read out errors, leave subsequent opens a clean slate */
155 spin_lock_irq(&dev
->err_lock
);
156 res
= dev
->errors
? (dev
->errors
== -EPIPE
? -EPIPE
: -EIO
) : 0;
158 spin_unlock_irq(&dev
->err_lock
);
160 mutex_unlock(&dev
->io_mutex
);
165 static void skel_read_bulk_callback(struct urb
*urb
)
167 struct usb_skel
*dev
;
171 spin_lock(&dev
->err_lock
);
172 /* sync/async unlink faults aren't errors */
174 if (!(urb
->status
== -ENOENT
||
175 urb
->status
== -ECONNRESET
||
176 urb
->status
== -ESHUTDOWN
))
177 dev_err(&dev
->interface
->dev
,
178 "%s - nonzero write bulk status received: %d\n",
179 __func__
, urb
->status
);
181 dev
->errors
= urb
->status
;
183 dev
->bulk_in_filled
= urb
->actual_length
;
185 dev
->ongoing_read
= 0;
186 spin_unlock(&dev
->err_lock
);
188 complete(&dev
->bulk_in_completion
);
191 static int skel_do_read_io(struct usb_skel
*dev
, size_t count
)
196 usb_fill_bulk_urb(dev
->bulk_in_urb
,
198 usb_rcvbulkpipe(dev
->udev
,
199 dev
->bulk_in_endpointAddr
),
201 min(dev
->bulk_in_size
, count
),
202 skel_read_bulk_callback
,
204 /* tell everybody to leave the URB alone */
205 spin_lock_irq(&dev
->err_lock
);
206 dev
->ongoing_read
= 1;
207 spin_unlock_irq(&dev
->err_lock
);
210 rv
= usb_submit_urb(dev
->bulk_in_urb
, GFP_KERNEL
);
212 dev_err(&dev
->interface
->dev
,
213 "%s - failed submitting read urb, error %d\n",
215 dev
->bulk_in_filled
= 0;
216 rv
= (rv
== -ENOMEM
) ? rv
: -EIO
;
217 spin_lock_irq(&dev
->err_lock
);
218 dev
->ongoing_read
= 0;
219 spin_unlock_irq(&dev
->err_lock
);
225 static ssize_t
skel_read(struct file
*file
, char *buffer
, size_t count
,
228 struct usb_skel
*dev
;
232 dev
= file
->private_data
;
234 /* if we cannot read at all, return EOF */
235 if (!dev
->bulk_in_urb
|| !count
)
238 /* no concurrent readers */
239 rv
= mutex_lock_interruptible(&dev
->io_mutex
);
243 if (!dev
->interface
) { /* disconnect() was called */
248 /* if IO is under way, we must not touch things */
250 spin_lock_irq(&dev
->err_lock
);
251 ongoing_io
= dev
->ongoing_read
;
252 spin_unlock_irq(&dev
->err_lock
);
255 /* nonblocking IO shall not wait */
256 if (file
->f_flags
& O_NONBLOCK
) {
261 * IO may take forever
262 * hence wait in an interruptible state
264 rv
= wait_for_completion_interruptible(&dev
->bulk_in_completion
);
268 * by waiting we also semiprocessed the urb
271 dev
->bulk_in_copied
= 0;
272 dev
->processed_urb
= 1;
275 if (!dev
->processed_urb
) {
277 * the URB hasn't been processed
280 wait_for_completion(&dev
->bulk_in_completion
);
281 dev
->bulk_in_copied
= 0;
282 dev
->processed_urb
= 1;
285 /* errors must be reported */
288 /* any error is reported once */
290 /* to preserve notifications about reset */
291 rv
= (rv
== -EPIPE
) ? rv
: -EIO
;
292 /* no data to deliver */
293 dev
->bulk_in_filled
= 0;
299 * if the buffer is filled we may satisfy the read
300 * else we need to start IO
303 if (dev
->bulk_in_filled
) {
304 /* we had read data */
305 size_t available
= dev
->bulk_in_filled
- dev
->bulk_in_copied
;
306 size_t chunk
= min(available
, count
);
310 * all data has been used
311 * actual IO needs to be done
313 rv
= skel_do_read_io(dev
, count
);
321 * chunk tells us how much shall be copied
324 if (copy_to_user(buffer
,
325 dev
->bulk_in_buffer
+ dev
->bulk_in_copied
,
331 dev
->bulk_in_copied
+= chunk
;
334 * if we are asked for more than we have,
335 * we start IO but don't wait
337 if (available
< count
)
338 skel_do_read_io(dev
, count
- chunk
);
340 /* no data in the buffer */
341 rv
= skel_do_read_io(dev
, count
);
344 else if (!(file
->f_flags
& O_NONBLOCK
))
349 mutex_unlock(&dev
->io_mutex
);
353 static void skel_write_bulk_callback(struct urb
*urb
)
355 struct usb_skel
*dev
;
359 /* sync/async unlink faults aren't errors */
361 if (!(urb
->status
== -ENOENT
||
362 urb
->status
== -ECONNRESET
||
363 urb
->status
== -ESHUTDOWN
))
364 dev_err(&dev
->interface
->dev
,
365 "%s - nonzero write bulk status received: %d\n",
366 __func__
, urb
->status
);
368 spin_lock(&dev
->err_lock
);
369 dev
->errors
= urb
->status
;
370 spin_unlock(&dev
->err_lock
);
373 /* free up our allocated buffer */
374 usb_free_coherent(urb
->dev
, urb
->transfer_buffer_length
,
375 urb
->transfer_buffer
, urb
->transfer_dma
);
379 static ssize_t
skel_write(struct file
*file
, const char *user_buffer
,
380 size_t count
, loff_t
*ppos
)
382 struct usb_skel
*dev
;
384 struct urb
*urb
= NULL
;
386 size_t writesize
= min(count
, (size_t)MAX_TRANSFER
);
388 dev
= file
->private_data
;
390 /* verify that we actually have some data to write */
395 * limit the number of URBs in flight to stop a user from using up all
398 if (!(file
->f_flags
& O_NONBLOCK
)) {
399 if (down_interruptible(&dev
->limit_sem
)) {
400 retval
= -ERESTARTSYS
;
404 if (down_trylock(&dev
->limit_sem
)) {
410 spin_lock_irq(&dev
->err_lock
);
411 retval
= dev
->errors
;
413 /* any error is reported once */
415 /* to preserve notifications about reset */
416 retval
= (retval
== -EPIPE
) ? retval
: -EIO
;
418 spin_unlock_irq(&dev
->err_lock
);
422 /* create a urb, and a buffer for it, and copy the data to the urb */
423 urb
= usb_alloc_urb(0, GFP_KERNEL
);
429 buf
= usb_alloc_coherent(dev
->udev
, writesize
, GFP_KERNEL
,
436 if (copy_from_user(buf
, user_buffer
, writesize
)) {
441 /* this lock makes sure we don't submit URBs to gone devices */
442 mutex_lock(&dev
->io_mutex
);
443 if (!dev
->interface
) { /* disconnect() was called */
444 mutex_unlock(&dev
->io_mutex
);
449 /* initialize the urb properly */
450 usb_fill_bulk_urb(urb
, dev
->udev
,
451 usb_sndbulkpipe(dev
->udev
, dev
->bulk_out_endpointAddr
),
452 buf
, writesize
, skel_write_bulk_callback
, dev
);
453 urb
->transfer_flags
|= URB_NO_TRANSFER_DMA_MAP
;
454 usb_anchor_urb(urb
, &dev
->submitted
);
456 /* send the data out the bulk port */
457 retval
= usb_submit_urb(urb
, GFP_KERNEL
);
458 mutex_unlock(&dev
->io_mutex
);
460 dev_err(&dev
->interface
->dev
,
461 "%s - failed submitting write urb, error %d\n",
467 * release our reference to this urb, the USB core will eventually free
476 usb_unanchor_urb(urb
);
479 usb_free_coherent(dev
->udev
, writesize
, buf
, urb
->transfer_dma
);
488 static const struct file_operations skel_fops
= {
489 .owner
= THIS_MODULE
,
493 .release
= skel_release
,
495 .llseek
= noop_llseek
,
499 * usb class driver info in order to get a minor number from the usb core,
500 * and to have the device registered with the driver core
502 static struct usb_class_driver skel_class
= {
505 .minor_base
= USB_SKEL_MINOR_BASE
,
508 static int skel_probe(struct usb_interface
*interface
,
509 const struct usb_device_id
*id
)
511 struct usb_skel
*dev
;
512 struct usb_host_interface
*iface_desc
;
513 struct usb_endpoint_descriptor
*endpoint
;
516 int retval
= -ENOMEM
;
518 /* allocate memory for our device state and initialize it */
519 dev
= kzalloc(sizeof(*dev
), GFP_KERNEL
);
521 dev_err(&interface
->dev
, "Out of memory\n");
524 kref_init(&dev
->kref
);
525 sema_init(&dev
->limit_sem
, WRITES_IN_FLIGHT
);
526 mutex_init(&dev
->io_mutex
);
527 spin_lock_init(&dev
->err_lock
);
528 init_usb_anchor(&dev
->submitted
);
529 init_completion(&dev
->bulk_in_completion
);
531 dev
->udev
= usb_get_dev(interface_to_usbdev(interface
));
532 dev
->interface
= interface
;
534 /* set up the endpoint information */
535 /* use only the first bulk-in and bulk-out endpoints */
536 iface_desc
= interface
->cur_altsetting
;
537 for (i
= 0; i
< iface_desc
->desc
.bNumEndpoints
; ++i
) {
538 endpoint
= &iface_desc
->endpoint
[i
].desc
;
540 if (!dev
->bulk_in_endpointAddr
&&
541 usb_endpoint_is_bulk_in(endpoint
)) {
542 /* we found a bulk in endpoint */
543 buffer_size
= usb_endpoint_maxp(endpoint
);
544 dev
->bulk_in_size
= buffer_size
;
545 dev
->bulk_in_endpointAddr
= endpoint
->bEndpointAddress
;
546 dev
->bulk_in_buffer
= kmalloc(buffer_size
, GFP_KERNEL
);
547 if (!dev
->bulk_in_buffer
) {
548 dev_err(&interface
->dev
,
549 "Could not allocate bulk_in_buffer\n");
552 dev
->bulk_in_urb
= usb_alloc_urb(0, GFP_KERNEL
);
553 if (!dev
->bulk_in_urb
) {
554 dev_err(&interface
->dev
,
555 "Could not allocate bulk_in_urb\n");
560 if (!dev
->bulk_out_endpointAddr
&&
561 usb_endpoint_is_bulk_out(endpoint
)) {
562 /* we found a bulk out endpoint */
563 dev
->bulk_out_endpointAddr
= endpoint
->bEndpointAddress
;
566 if (!(dev
->bulk_in_endpointAddr
&& dev
->bulk_out_endpointAddr
)) {
567 dev_err(&interface
->dev
,
568 "Could not find both bulk-in and bulk-out endpoints\n");
572 /* save our data pointer in this interface device */
573 usb_set_intfdata(interface
, dev
);
575 /* we can register the device now, as it is ready */
576 retval
= usb_register_dev(interface
, &skel_class
);
578 /* something prevented us from registering this driver */
579 dev_err(&interface
->dev
,
580 "Not able to get a minor for this device.\n");
581 usb_set_intfdata(interface
, NULL
);
585 /* let the user know what node this device is now attached to */
586 dev_info(&interface
->dev
,
587 "USB Skeleton device now attached to USBSkel-%d",
593 /* this frees allocated memory */
594 kref_put(&dev
->kref
, skel_delete
);
598 static void skel_disconnect(struct usb_interface
*interface
)
600 struct usb_skel
*dev
;
601 int minor
= interface
->minor
;
603 dev
= usb_get_intfdata(interface
);
604 usb_set_intfdata(interface
, NULL
);
606 /* give back our minor */
607 usb_deregister_dev(interface
, &skel_class
);
609 /* prevent more I/O from starting */
610 mutex_lock(&dev
->io_mutex
);
611 dev
->interface
= NULL
;
612 mutex_unlock(&dev
->io_mutex
);
614 usb_kill_anchored_urbs(&dev
->submitted
);
616 /* decrement our usage count */
617 kref_put(&dev
->kref
, skel_delete
);
619 dev_info(&interface
->dev
, "USB Skeleton #%d now disconnected", minor
);
622 static void skel_draw_down(struct usb_skel
*dev
)
626 time
= usb_wait_anchor_empty_timeout(&dev
->submitted
, 1000);
628 usb_kill_anchored_urbs(&dev
->submitted
);
629 usb_kill_urb(dev
->bulk_in_urb
);
632 static int skel_suspend(struct usb_interface
*intf
, pm_message_t message
)
634 struct usb_skel
*dev
= usb_get_intfdata(intf
);
642 static int skel_resume(struct usb_interface
*intf
)
647 static int skel_pre_reset(struct usb_interface
*intf
)
649 struct usb_skel
*dev
= usb_get_intfdata(intf
);
651 mutex_lock(&dev
->io_mutex
);
657 static int skel_post_reset(struct usb_interface
*intf
)
659 struct usb_skel
*dev
= usb_get_intfdata(intf
);
661 /* we are sure no URBs are active - no locking needed */
662 dev
->errors
= -EPIPE
;
663 mutex_unlock(&dev
->io_mutex
);
668 static struct usb_driver skel_driver
= {
671 .disconnect
= skel_disconnect
,
672 .suspend
= skel_suspend
,
673 .resume
= skel_resume
,
674 .pre_reset
= skel_pre_reset
,
675 .post_reset
= skel_post_reset
,
676 .id_table
= skel_table
,
677 .supports_autosuspend
= 1,
680 module_usb_driver(skel_driver
);
682 MODULE_LICENSE("GPL");