urb.c

linux-2.6.15.6

	temp = usb_pipetype (pipe);
	is_out = usb_pipeout (pipe);

	if (!usb_pipecontrol (pipe) && dev->state < USB_STATE_CONFIGURED)
		return -ENODEV;

	/* FIXME there should be a sharable lock protecting us against
	 * config/altsetting changes and disconnects, kicking in here.
	 * (here == before maxpacket, and eventually endpoint type,
	 * checks get made.)
	 */

	max = usb_maxpacket (dev, pipe, is_out);
	if (max <= 0) {
		dev_dbg(&dev->dev,
			"bogus endpoint ep%d%s in %s (bad maxpacket %d)\n",
			usb_pipeendpoint (pipe), is_out ? "out" : "in",
			__FUNCTION__, max);
		return -EMSGSIZE;
	}

	/* periodic transfers limit size per frame/uframe,
	 * but drivers only control those sizes for ISO.
	 * while we're checking, initialize return status.
	 */
	if (temp == PIPE_ISOCHRONOUS) {
		int	n, len;

		/* "high bandwidth" mode, 1-3 packets/uframe? */
		if (dev->speed == USB_SPEED_HIGH) {
			int	mult = 1 + ((max >> 11) & 0x03);
			max &= 0x07ff;
			max *= mult;
		}

		if (urb->number_of_packets <= 0)		    
			return -EINVAL;
		for (n = 0; n < urb->number_of_packets; n++) {
			len = urb->iso_frame_desc [n].length;
			if (len < 0 || len > max) 
				return -EMSGSIZE;
			urb->iso_frame_desc [n].status = -EXDEV;
			urb->iso_frame_desc [n].actual_length = 0;
		}
	}

	/* the I/O buffer must be mapped/unmapped, except when length=0 */
	if (urb->transfer_buffer_length < 0)
		return -EMSGSIZE;

#ifdef DEBUG
	/* stuff that drivers shouldn't do, but which shouldn't
	 * cause problems in HCDs if they get it wrong.
	 */
	{
	unsigned int	orig_flags = urb->transfer_flags;
	unsigned int	allowed;

	/* enforce simple/standard policy */
	allowed = (URB_NO_TRANSFER_DMA_MAP | URB_NO_SETUP_DMA_MAP |
			URB_NO_INTERRUPT);
	switch (temp) {
	case PIPE_BULK:
		if (is_out)
			allowed |= URB_ZERO_PACKET;
		/* FALLTHROUGH */
	case PIPE_CONTROL:
		allowed |= URB_NO_FSBR;	/* only affects UHCI */
		/* FALLTHROUGH */
	default:			/* all non-iso endpoints */
		if (!is_out)
			allowed |= URB_SHORT_NOT_OK;
		break;
	case PIPE_ISOCHRONOUS:
		allowed |= URB_ISO_ASAP;
		break;
	}
	urb->transfer_flags &= allowed;

	/* fail if submitter gave bogus flags */
	if (urb->transfer_flags != orig_flags) {
		err ("BOGUS urb flags, %x --> %x",
			orig_flags, urb->transfer_flags);
		return -EINVAL;
	}
	}
#endif
	/*
	 * Force periodic transfer intervals to be legal values that are
	 * a power of two (so HCDs don't need to).
	 *
	 * FIXME want bus->{intr,iso}_sched_horizon values here.  Each HC
	 * supports different values... this uses EHCI/UHCI defaults (and
	 * EHCI can use smaller non-default values).
	 */
	switch (temp) {
	case PIPE_ISOCHRONOUS:
	case PIPE_INTERRUPT:
		/* too small? */
		if (urb->interval <= 0)
			return -EINVAL;
		/* too big? */
		switch (dev->speed) {
		case USB_SPEED_HIGH:	/* units are microframes */
			// NOTE usb handles 2^15
			if (urb->interval > (1024 * 8))
				urb->interval = 1024 * 8;
			temp = 1024 * 8;
			break;
		case USB_SPEED_FULL:	/* units are frames/msec */
		case USB_SPEED_LOW:
			if (temp == PIPE_INTERRUPT) {
				if (urb->interval > 255)
					return -EINVAL;
				// NOTE ohci only handles up to 32
				temp = 128;
			} else {
				if (urb->interval > 1024)
					urb->interval = 1024;
				// NOTE usb and ohci handle up to 2^15
				temp = 1024;
			}
			break;
		default:
			return -EINVAL;
		}
		/* power of two? */
		while (temp > urb->interval)
			temp >>= 1;
		urb->interval = temp;
	}

	return op->submit_urb (urb, mem_flags);
}

/*-------------------------------------------------------------------*/

/**
 * usb_unlink_urb - abort/cancel a transfer request for an endpoint
 * @urb: pointer to urb describing a previously submitted request,
 *	may be NULL
 *
 * This routine cancels an in-progress request.  URBs complete only
 * once per submission, and may be canceled only once per submission.
 * Successful cancellation means the requests's completion handler will
 * be called with a status code indicating that the request has been
 * canceled (rather than any other code) and will quickly be removed
 * from host controller data structures.
 *
 * This request is always asynchronous.
 * Success is indicated by returning -EINPROGRESS,
 * at which time the URB will normally have been unlinked but not yet
 * given back to the device driver.  When it is called, the completion
 * function will see urb->status == -ECONNRESET.  Failure is indicated
 * by any other return value.  Unlinking will fail when the URB is not
 * currently "linked" (i.e., it was never submitted, or it was unlinked
 * before, or the hardware is already finished with it), even if the
 * completion handler has not yet run.
 *
 * Unlinking and Endpoint Queues:
 *
 * Host Controller Drivers (HCDs) place all the URBs for a particular
 * endpoint in a queue.  Normally the queue advances as the controller
 * hardware processes each request.  But when an URB terminates with an
 * error its queue stops, at least until that URB's completion routine
 * returns.  It is guaranteed that the queue will not restart until all
 * its unlinked URBs have been fully retired, with their completion
 * routines run, even if that's not until some time after the original
 * completion handler returns.  Normally the same behavior and guarantees
 * apply when an URB terminates because it was unlinked; however if an
 * URB is unlinked before the hardware has started to execute it, then
 * its queue is not guaranteed to stop until all the preceding URBs have
 * completed.
 *
 * This means that USB device drivers can safely build deep queues for
 * large or complex transfers, and clean them up reliably after any sort
 * of aborted transfer by unlinking all pending URBs at the first fault.
 *
 * Note that an URB terminating early because a short packet was received
 * will count as an error if and only if the URB_SHORT_NOT_OK flag is set.
 * Also, that all unlinks performed in any URB completion handler must
 * be asynchronous.
 *
 * Queues for isochronous endpoints are treated differently, because they
 * advance at fixed rates.  Such queues do not stop when an URB is unlinked.
 * An unlinked URB may leave a gap in the stream of packets.  It is undefined
 * whether such gaps can be filled in.
 *
 * When a control URB terminates with an error, it is likely that the
 * status stage of the transfer will not take place, even if it is merely
 * a soft error resulting from a short-packet with URB_SHORT_NOT_OK set.
 */
int usb_unlink_urb(struct urb *urb)
{
	if (!urb)
		return -EINVAL;
	if (!(urb->dev && urb->dev->bus && urb->dev->bus->op))
		return -ENODEV;
	return urb->dev->bus->op->unlink_urb(urb, -ECONNRESET);
}

/**
 * usb_kill_urb - cancel a transfer request and wait for it to finish
 * @urb: pointer to URB describing a previously submitted request,
 *	may be NULL
 *
 * This routine cancels an in-progress request.  It is guaranteed that
 * upon return all completion handlers will have finished and the URB
 * will be totally idle and available for reuse.  These features make
 * this an ideal way to stop I/O in a disconnect() callback or close()
 * function.  If the request has not already finished or been unlinked
 * the completion handler will see urb->status == -ENOENT.
 *
 * While the routine is running, attempts to resubmit the URB will fail
 * with error -EPERM.  Thus even if the URB's completion handler always
 * tries to resubmit, it will not succeed and the URB will become idle.
 *
 * This routine may not be used in an interrupt context (such as a bottom
 * half or a completion handler), or when holding a spinlock, or in other
 * situations where the caller can't schedule().
 */
void usb_kill_urb(struct urb *urb)
{
	if (!(urb && urb->dev && urb->dev->bus && urb->dev->bus->op))
		return;
	spin_lock_irq(&urb->lock);
	++urb->reject;
	spin_unlock_irq(&urb->lock);

	urb->dev->bus->op->unlink_urb(urb, -ENOENT);
	wait_event(usb_kill_urb_queue, atomic_read(&urb->use_count) == 0);

	spin_lock_irq(&urb->lock);
	--urb->reject;
	spin_unlock_irq(&urb->lock);
}

EXPORT_SYMBOL(usb_init_urb);
EXPORT_SYMBOL(usb_alloc_urb);
EXPORT_SYMBOL(usb_free_urb);
EXPORT_SYMBOL(usb_get_urb);
EXPORT_SYMBOL(usb_submit_urb);
EXPORT_SYMBOL(usb_unlink_urb);
EXPORT_SYMBOL(usb_kill_urb);