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 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 */
68 struct mutex io_mutex; /* synchronize I/O with disconnect */
69 struct completion bulk_in_completion; /* to wait for an ongoing read */
71 #define to_skel_dev(d) container_of(d, struct usb_skel, kref)
73 static struct usb_driver skel_driver;
74 static void skel_draw_down(struct usb_skel *dev);
76 static void skel_delete(struct kref *kref)
78 struct usb_skel *dev = to_skel_dev(kref);
80 usb_free_urb(dev->bulk_in_urb);
81 usb_put_dev(dev->udev);
82 kfree(dev->bulk_in_buffer);
86 static int skel_open(struct inode *inode, struct file *file)
89 struct usb_interface *interface;
93 subminor = iminor(inode);
95 interface = usb_find_interface(&skel_driver, subminor);
97 err("%s - error, can't find device for minor %d",
103 dev = usb_get_intfdata(interface);
109 /* increment our usage count for the device */
110 kref_get(&dev->kref);
112 /* lock the device to allow correctly handling errors
114 mutex_lock(&dev->io_mutex);
116 if (!dev->open_count++) {
117 retval = usb_autopm_get_interface(interface);
120 mutex_unlock(&dev->io_mutex);
121 kref_put(&dev->kref, skel_delete);
124 } /* else { //uncomment this block if you want exclusive open
127 mutex_unlock(&dev->io_mutex);
128 kref_put(&dev->kref, skel_delete);
131 /* prevent the device from being autosuspended */
133 /* save our object in the file's private structure */
134 file->private_data = dev;
135 mutex_unlock(&dev->io_mutex);
141 static int skel_release(struct inode *inode, struct file *file)
143 struct usb_skel *dev;
145 dev = file->private_data;
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);
155 /* decrement the count on our device */
156 kref_put(&dev->kref, skel_delete);
160 static int skel_flush(struct file *file, fl_owner_t id)
162 struct usb_skel *dev;
165 dev = file->private_data;
169 /* wait for io to stop */
170 mutex_lock(&dev->io_mutex);
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;
177 spin_unlock_irq(&dev->err_lock);
179 mutex_unlock(&dev->io_mutex);
184 static void skel_read_bulk_callback(struct urb *urb)
186 struct usb_skel *dev;
190 spin_lock(&dev->err_lock);
191 /* sync/async unlink faults aren't errors */
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);
199 dev->errors = urb->status;
201 dev->bulk_in_filled = urb->actual_length;
203 dev->ongoing_read = 0;
204 spin_unlock(&dev->err_lock);
206 complete(&dev->bulk_in_completion);
209 static int skel_do_read_io(struct usb_skel *dev, size_t count)
214 usb_fill_bulk_urb(dev->bulk_in_urb,
216 usb_rcvbulkpipe(dev->udev,
217 dev->bulk_in_endpointAddr),
219 min(dev->bulk_in_size, count),
220 skel_read_bulk_callback,
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);
228 rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
230 err("%s - failed submitting read urb, error %d",
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);
242 static ssize_t skel_read(struct file *file, char *buffer, size_t count,
245 struct usb_skel *dev;
249 dev = file->private_data;
251 /* if we cannot read at all, return EOF */
252 if (!dev->bulk_in_urb || !count)
255 /* no concurrent readers */
256 rv = mutex_lock_interruptible(&dev->io_mutex);
260 if (!dev->interface) { /* disconnect() was called */
265 /* if IO is under way, we must not touch things */
267 spin_lock_irq(&dev->err_lock);
268 ongoing_io = dev->ongoing_read;
269 spin_unlock_irq(&dev->err_lock);
272 /* nonblocking IO shall not wait */
273 if (file->f_flags & O_NONBLOCK) {
278 * IO may take forever
279 * hence wait in an interruptible state
281 rv = wait_for_completion_interruptible(&dev->bulk_in_completion);
285 * by waiting we also semiprocessed the urb
288 dev->bulk_in_copied = 0;
289 dev->processed_urb = 1;
292 if (!dev->processed_urb) {
294 * the URB hasn't been processed
297 wait_for_completion(&dev->bulk_in_completion);
298 dev->bulk_in_copied = 0;
299 dev->processed_urb = 1;
302 /* errors must be reported */
305 /* any error is reported once */
307 /* to preserve notifications about reset */
308 rv = (rv == -EPIPE) ? rv : -EIO;
309 /* no data to deliver */
310 dev->bulk_in_filled = 0;
316 * if the buffer is filled we may satisfy the read
317 * else we need to start IO
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);
327 * all data has been used
328 * actual IO needs to be done
330 rv = skel_do_read_io(dev, count);
338 * chunk tells us how much shall be copied
341 if (copy_to_user(buffer,
342 dev->bulk_in_buffer + dev->bulk_in_copied,
348 dev->bulk_in_copied += chunk;
351 * if we are asked for more than we have,
352 * we start IO but don't wait
354 if (available < count)
355 skel_do_read_io(dev, count - chunk);
357 /* no data in the buffer */
358 rv = skel_do_read_io(dev, count);
361 else if (!(file->f_flags & O_NONBLOCK))
366 mutex_unlock(&dev->io_mutex);
370 static void skel_write_bulk_callback(struct urb *urb)
372 struct usb_skel *dev;
376 /* sync/async unlink faults aren't errors */
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);
384 spin_lock(&dev->err_lock);
385 dev->errors = urb->status;
386 spin_unlock(&dev->err_lock);
389 /* free up our allocated buffer */
390 usb_free_coherent(urb->dev, urb->transfer_buffer_length,
391 urb->transfer_buffer, urb->transfer_dma);
395 static ssize_t skel_write(struct file *file, const char *user_buffer,
396 size_t count, loff_t *ppos)
398 struct usb_skel *dev;
400 struct urb *urb = NULL;
402 size_t writesize = min(count, (size_t)MAX_TRANSFER);
404 dev = file->private_data;
406 /* verify that we actually have some data to write */
411 * limit the number of URBs in flight to stop a user from using up all
414 if (!(file->f_flags & O_NONBLOCK)) {
415 if (down_interruptible(&dev->limit_sem)) {
416 retval = -ERESTARTSYS;
420 if (down_trylock(&dev->limit_sem)) {
426 spin_lock_irq(&dev->err_lock);
427 retval = dev->errors;
429 /* any error is reported once */
431 /* to preserve notifications about reset */
432 retval = (retval == -EPIPE) ? retval : -EIO;
434 spin_unlock_irq(&dev->err_lock);
438 /* create a urb, and a buffer for it, and copy the data to the urb */
439 urb = usb_alloc_urb(0, GFP_KERNEL);
445 buf = usb_alloc_coherent(dev->udev, writesize, GFP_KERNEL,
452 if (copy_from_user(buf, user_buffer, writesize)) {
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);
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);
472 /* send the data out the bulk port */
473 retval = usb_submit_urb(urb, GFP_KERNEL);
474 mutex_unlock(&dev->io_mutex);
476 err("%s - failed submitting write urb, error %d", __func__,
482 * release our reference to this urb, the USB core will eventually free
491 usb_unanchor_urb(urb);
494 usb_free_coherent(dev->udev, writesize, buf, urb->transfer_dma);
503 static const struct file_operations skel_fops = {
504 .owner = THIS_MODULE,
508 .release = skel_release,
510 .llseek = noop_llseek,
514 * usb class driver info in order to get a minor number from the usb core,
515 * and to have the device registered with the driver core
517 static struct usb_class_driver skel_class = {
520 .minor_base = USB_SKEL_MINOR_BASE,
523 static int skel_probe(struct usb_interface *interface,
524 const struct usb_device_id *id)
526 struct usb_skel *dev;
527 struct usb_host_interface *iface_desc;
528 struct usb_endpoint_descriptor *endpoint;
531 int retval = -ENOMEM;
533 /* allocate memory for our device state and initialize it */
534 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
536 err("Out of memory");
539 kref_init(&dev->kref);
540 sema_init(&dev->limit_sem, WRITES_IN_FLIGHT);
541 mutex_init(&dev->io_mutex);
542 spin_lock_init(&dev->err_lock);
543 init_usb_anchor(&dev->submitted);
544 init_completion(&dev->bulk_in_completion);
546 dev->udev = usb_get_dev(interface_to_usbdev(interface));
547 dev->interface = interface;
549 /* set up the endpoint information */
550 /* use only the first bulk-in and bulk-out endpoints */
551 iface_desc = interface->cur_altsetting;
552 for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
553 endpoint = &iface_desc->endpoint[i].desc;
555 if (!dev->bulk_in_endpointAddr &&
556 usb_endpoint_is_bulk_in(endpoint)) {
557 /* we found a bulk in endpoint */
558 buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
559 dev->bulk_in_size = buffer_size;
560 dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
561 dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
562 if (!dev->bulk_in_buffer) {
563 err("Could not allocate bulk_in_buffer");
566 dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
567 if (!dev->bulk_in_urb) {
568 err("Could not allocate bulk_in_urb");
573 if (!dev->bulk_out_endpointAddr &&
574 usb_endpoint_is_bulk_out(endpoint)) {
575 /* we found a bulk out endpoint */
576 dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
579 if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
580 err("Could not find both bulk-in and bulk-out endpoints");
584 /* save our data pointer in this interface device */
585 usb_set_intfdata(interface, dev);
587 /* we can register the device now, as it is ready */
588 retval = usb_register_dev(interface, &skel_class);
590 /* something prevented us from registering this driver */
591 err("Not able to get a minor for this device.");
592 usb_set_intfdata(interface, NULL);
596 /* let the user know what node this device is now attached to */
597 dev_info(&interface->dev,
598 "USB Skeleton device now attached to USBSkel-%d",
604 /* this frees allocated memory */
605 kref_put(&dev->kref, skel_delete);
609 static void skel_disconnect(struct usb_interface *interface)
611 struct usb_skel *dev;
612 int minor = interface->minor;
614 dev = usb_get_intfdata(interface);
615 usb_set_intfdata(interface, NULL);
617 /* give back our minor */
618 usb_deregister_dev(interface, &skel_class);
620 /* prevent more I/O from starting */
621 mutex_lock(&dev->io_mutex);
622 dev->interface = NULL;
623 mutex_unlock(&dev->io_mutex);
625 usb_kill_anchored_urbs(&dev->submitted);
627 /* decrement our usage count */
628 kref_put(&dev->kref, skel_delete);
630 dev_info(&interface->dev, "USB Skeleton #%d now disconnected", minor);
633 static void skel_draw_down(struct usb_skel *dev)
637 time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
639 usb_kill_anchored_urbs(&dev->submitted);
640 usb_kill_urb(dev->bulk_in_urb);
643 static int skel_suspend(struct usb_interface *intf, pm_message_t message)
645 struct usb_skel *dev = usb_get_intfdata(intf);
653 static int skel_resume(struct usb_interface *intf)
658 static int skel_pre_reset(struct usb_interface *intf)
660 struct usb_skel *dev = usb_get_intfdata(intf);
662 mutex_lock(&dev->io_mutex);
668 static int skel_post_reset(struct usb_interface *intf)
670 struct usb_skel *dev = usb_get_intfdata(intf);
672 /* we are sure no URBs are active - no locking needed */
673 dev->errors = -EPIPE;
674 mutex_unlock(&dev->io_mutex);
679 static struct usb_driver skel_driver = {
682 .disconnect = skel_disconnect,
683 .suspend = skel_suspend,
684 .resume = skel_resume,
685 .pre_reset = skel_pre_reset,
686 .post_reset = skel_post_reset,
687 .id_table = skel_table,
688 .supports_autosuspend = 1,
691 static int __init usb_skel_init(void)
695 /* register this driver with the USB subsystem */
696 result = usb_register(&skel_driver);
698 err("usb_register failed. Error number %d", result);
703 static void __exit usb_skel_exit(void)
705 /* deregister this driver with the USB subsystem */
706 usb_deregister(&skel_driver);
709 module_init(usb_skel_init);
710 module_exit(usb_skel_exit);
712 MODULE_LICENSE("GPL");