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/slab.h>
18 #include <linux/module.h>
19 #include <linux/kref.h>
20 #include <linux/uaccess.h>
21 #include <linux/usb.h>
22 #include <linux/mutex.h>
25 /* Define these values to match your devices */
26 #define USB_SKEL_VENDOR_ID 0xfff0
27 #define USB_SKEL_PRODUCT_ID 0xfff0
29 /* table of devices that work with this driver */
30 static const struct usb_device_id skel_table[] = {
31 { USB_DEVICE(USB_SKEL_VENDOR_ID, USB_SKEL_PRODUCT_ID) },
32 { } /* Terminating entry */
34 MODULE_DEVICE_TABLE(usb, skel_table);
37 /* Get a minor range for your devices from the usb maintainer */
38 #define USB_SKEL_MINOR_BASE 192
40 /* our private defines. if this grows any larger, use your own .h file */
41 #define MAX_TRANSFER (PAGE_SIZE - 512)
42 /* MAX_TRANSFER is chosen so that the VM is not stressed by
43 allocations > PAGE_SIZE and the number of packets in a page
44 is an integer 512 is the largest possible packet on EHCI */
45 #define WRITES_IN_FLIGHT 8
46 /* arbitrarily chosen */
48 /* Structure to hold all of our device specific stuff */
50 struct usb_device *udev; /* the usb device for this device */
51 struct usb_interface *interface; /* the interface for this device */
52 struct semaphore limit_sem; /* limiting the number of writes in progress */
53 struct usb_anchor submitted; /* in case we need to retract our submissions */
54 struct urb *bulk_in_urb; /* the urb to read data with */
55 unsigned char *bulk_in_buffer; /* the buffer to receive data */
56 size_t bulk_in_size; /* the size of the receive buffer */
57 size_t bulk_in_filled; /* number of bytes in the buffer */
58 size_t bulk_in_copied; /* already copied to user space */
59 __u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */
60 __u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */
61 int errors; /* the last request tanked */
62 bool ongoing_read; /* a read is going on */
63 spinlock_t err_lock; /* lock for errors */
65 struct mutex io_mutex; /* synchronize I/O with disconnect */
66 unsigned long disconnected:1;
67 wait_queue_head_t bulk_in_wait; /* to wait for an ongoing read */
69 #define to_skel_dev(d) container_of(d, struct usb_skel, kref)
71 static struct usb_driver skel_driver;
72 static void skel_draw_down(struct usb_skel *dev);
74 static void skel_delete(struct kref *kref)
76 struct usb_skel *dev = to_skel_dev(kref);
78 usb_free_urb(dev->bulk_in_urb);
79 usb_put_intf(dev->interface);
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 usb_autopm_put_interface(dev->interface);
133 /* decrement the count on our device */
134 kref_put(&dev->kref, skel_delete);
138 static int skel_flush(struct file *file, fl_owner_t id)
140 struct usb_skel *dev;
143 dev = file->private_data;
147 /* wait for io to stop */
148 mutex_lock(&dev->io_mutex);
151 /* read out errors, leave subsequent opens a clean slate */
152 spin_lock_irq(&dev->err_lock);
153 res = dev->errors ? (dev->errors == -EPIPE ? -EPIPE : -EIO) : 0;
155 spin_unlock_irq(&dev->err_lock);
157 mutex_unlock(&dev->io_mutex);
162 static void skel_read_bulk_callback(struct urb *urb)
164 struct usb_skel *dev;
168 spin_lock(&dev->err_lock);
169 /* sync/async unlink faults aren't errors */
171 if (!(urb->status == -ENOENT ||
172 urb->status == -ECONNRESET ||
173 urb->status == -ESHUTDOWN))
174 dev_err(&dev->interface->dev,
175 "%s - nonzero write bulk status received: %d\n",
176 __func__, urb->status);
178 dev->errors = urb->status;
180 dev->bulk_in_filled = urb->actual_length;
182 dev->ongoing_read = 0;
183 spin_unlock(&dev->err_lock);
185 wake_up_interruptible(&dev->bulk_in_wait);
188 static int skel_do_read_io(struct usb_skel *dev, size_t count)
193 usb_fill_bulk_urb(dev->bulk_in_urb,
195 usb_rcvbulkpipe(dev->udev,
196 dev->bulk_in_endpointAddr),
198 min(dev->bulk_in_size, count),
199 skel_read_bulk_callback,
201 /* tell everybody to leave the URB alone */
202 spin_lock_irq(&dev->err_lock);
203 dev->ongoing_read = 1;
204 spin_unlock_irq(&dev->err_lock);
206 /* submit bulk in urb, which means no data to deliver */
207 dev->bulk_in_filled = 0;
208 dev->bulk_in_copied = 0;
211 rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
213 dev_err(&dev->interface->dev,
214 "%s - failed submitting read urb, error %d\n",
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->disconnected) { /* 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_event_interruptible(dev->bulk_in_wait, (!dev->ongoing_read));
269 /* errors must be reported */
272 /* any error is reported once */
274 /* to preserve notifications about reset */
275 rv = (rv == -EPIPE) ? rv : -EIO;
281 * if the buffer is filled we may satisfy the read
282 * else we need to start IO
285 if (dev->bulk_in_filled) {
286 /* we had read data */
287 size_t available = dev->bulk_in_filled - dev->bulk_in_copied;
288 size_t chunk = min(available, count);
292 * all data has been used
293 * actual IO needs to be done
295 rv = skel_do_read_io(dev, count);
303 * chunk tells us how much shall be copied
306 if (copy_to_user(buffer,
307 dev->bulk_in_buffer + dev->bulk_in_copied,
313 dev->bulk_in_copied += chunk;
316 * if we are asked for more than we have,
317 * we start IO but don't wait
319 if (available < count)
320 skel_do_read_io(dev, count - chunk);
322 /* no data in the buffer */
323 rv = skel_do_read_io(dev, count);
330 mutex_unlock(&dev->io_mutex);
334 static void skel_write_bulk_callback(struct urb *urb)
336 struct usb_skel *dev;
340 /* sync/async unlink faults aren't errors */
342 if (!(urb->status == -ENOENT ||
343 urb->status == -ECONNRESET ||
344 urb->status == -ESHUTDOWN))
345 dev_err(&dev->interface->dev,
346 "%s - nonzero write bulk status received: %d\n",
347 __func__, urb->status);
349 spin_lock(&dev->err_lock);
350 dev->errors = urb->status;
351 spin_unlock(&dev->err_lock);
354 /* free up our allocated buffer */
355 usb_free_coherent(urb->dev, urb->transfer_buffer_length,
356 urb->transfer_buffer, urb->transfer_dma);
360 static ssize_t skel_write(struct file *file, const char *user_buffer,
361 size_t count, loff_t *ppos)
363 struct usb_skel *dev;
365 struct urb *urb = NULL;
367 size_t writesize = min(count, (size_t)MAX_TRANSFER);
369 dev = file->private_data;
371 /* verify that we actually have some data to write */
376 * limit the number of URBs in flight to stop a user from using up all
379 if (!(file->f_flags & O_NONBLOCK)) {
380 if (down_interruptible(&dev->limit_sem)) {
381 retval = -ERESTARTSYS;
385 if (down_trylock(&dev->limit_sem)) {
391 spin_lock_irq(&dev->err_lock);
392 retval = dev->errors;
394 /* any error is reported once */
396 /* to preserve notifications about reset */
397 retval = (retval == -EPIPE) ? retval : -EIO;
399 spin_unlock_irq(&dev->err_lock);
403 /* create a urb, and a buffer for it, and copy the data to the urb */
404 urb = usb_alloc_urb(0, GFP_KERNEL);
410 buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
417 if (copy_from_user(buf, user_buffer, writesize)) {
422 /* this lock makes sure we don't submit URBs to gone devices */
423 mutex_lock(&dev->io_mutex);
424 if (dev->disconnected) { /* disconnect() was called */
425 mutex_unlock(&dev->io_mutex);
430 /* initialize the urb properly */
431 usb_fill_bulk_urb(urb, dev->udev,
432 usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
433 buf, writesize, skel_write_bulk_callback, dev);
434 urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
435 usb_anchor_urb(urb, &dev->submitted);
437 /* send the data out the bulk port */
438 retval = usb_submit_urb(urb, GFP_KERNEL);
439 mutex_unlock(&dev->io_mutex);
441 dev_err(&dev->interface->dev,
442 "%s - failed submitting write urb, error %d\n",
448 * release our reference to this urb, the USB core will eventually free
457 usb_unanchor_urb(urb);
460 usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
469 static const struct file_operations skel_fops = {
470 .owner = THIS_MODULE,
474 .release = skel_release,
476 .llseek = noop_llseek,
480 * usb class driver info in order to get a minor number from the usb core,
481 * and to have the device registered with the driver core
483 static struct usb_class_driver skel_class = {
486 .minor_base = USB_SKEL_MINOR_BASE,
489 static int skel_probe(struct usb_interface *interface,
490 const struct usb_device_id *id)
492 struct usb_skel *dev;
493 struct usb_host_interface *iface_desc;
494 struct usb_endpoint_descriptor *endpoint;
497 int retval = -ENOMEM;
499 /* allocate memory for our device state and initialize it */
500 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
503 kref_init(&dev->kref);
504 sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
505 mutex_init(&dev->io_mutex);
506 spin_lock_init(&dev->err_lock);
507 init_usb_anchor(&dev->submitted);
508 init_waitqueue_head(&dev->bulk_in_wait);
510 dev->udev = usb_get_dev(interface_to_usbdev(interface));
511 dev->interface = usb_get_intf(interface);
513 /* set up the endpoint information */
514 /* use only the first bulk-in and bulk-out endpoints */
515 iface_desc = interface->cur_altsetting;
516 for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
517 endpoint = &iface_desc->endpoint[i].desc;
519 if (!dev->bulk_in_endpointAddr &&
520 usb_endpoint_is_bulk_in(endpoint)) {
521 /* we found a bulk in endpoint */
522 buffer_size = usb_endpoint_maxp(endpoint);
523 dev->bulk_in_size = buffer_size;
524 dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
525 dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
526 if (!dev->bulk_in_buffer)
528 dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
529 if (!dev->bulk_in_urb)
533 if (!dev->bulk_out_endpointAddr &&
534 usb_endpoint_is_bulk_out(endpoint)) {
535 /* we found a bulk out endpoint */
536 dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
539 if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
540 dev_err(&interface->dev,
541 "Could not find both bulk-in and bulk-out endpoints\n");
545 /* save our data pointer in this interface device */
546 usb_set_intfdata(interface, dev);
548 /* we can register the device now, as it is ready */
549 retval = usb_register_dev(interface, &skel_class);
551 /* something prevented us from registering this driver */
552 dev_err(&interface->dev,
553 "Not able to get a minor for this device.\n");
554 usb_set_intfdata(interface, NULL);
558 /* let the user know what node this device is now attached to */
559 dev_info(&interface->dev,
560 "USB Skeleton device now attached to USBSkel-%d",
566 /* this frees allocated memory */
567 kref_put(&dev->kref, skel_delete);
571 static void skel_disconnect(struct usb_interface *interface)
573 struct usb_skel *dev;
574 int minor = interface->minor;
576 dev = usb_get_intfdata(interface);
577 usb_set_intfdata(interface, NULL);
579 /* give back our minor */
580 usb_deregister_dev(interface, &skel_class);
582 /* prevent more I/O from starting */
583 mutex_lock(&dev->io_mutex);
584 dev->disconnected = 1;
585 mutex_unlock(&dev->io_mutex);
587 usb_kill_anchored_urbs(&dev->submitted);
589 /* decrement our usage count */
590 kref_put(&dev->kref, skel_delete);
592 dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
595 static void skel_draw_down(struct usb_skel *dev)
599 time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
601 usb_kill_anchored_urbs(&dev->submitted);
602 usb_kill_urb(dev->bulk_in_urb);
605 static int skel_suspend(struct usb_interface *intf, pm_message_t message)
607 struct usb_skel *dev = usb_get_intfdata(intf);
615 static int skel_resume(struct usb_interface *intf)
620 static int skel_pre_reset(struct usb_interface *intf)
622 struct usb_skel *dev = usb_get_intfdata(intf);
624 mutex_lock(&dev->io_mutex);
630 static int skel_post_reset(struct usb_interface *intf)
632 struct usb_skel *dev = usb_get_intfdata(intf);
634 /* we are sure no URBs are active - no locking needed */
635 dev->errors = -EPIPE;
636 mutex_unlock(&dev->io_mutex);
641 static struct usb_driver skel_driver = {
644 .disconnect = skel_disconnect,
645 .suspend = skel_suspend,
646 .resume = skel_resume,
647 .pre_reset = skel_pre_reset,
648 .post_reset = skel_post_reset,
649 .id_table = skel_table,
650 .supports_autosuspend = 1,
653 module_usb_driver(skel_driver);
655 MODULE_LICENSE("GPL");