hcd.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 1,625 行 · 第 1/4 页

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

/**
 * usb_calc_bus_time - approximate periodic transaction time in nanoseconds
 * @speed: from dev->speed; USB_SPEED_{LOW,FULL,HIGH}
 * @is_input: true iff the transaction sends data to the host
 * @isoc: true for isochronous transactions, false for interrupt ones
 * @bytecount: how many bytes in the transaction.
 *
 * Returns approximate bus time in nanoseconds for a periodic transaction.
 * See USB 2.0 spec section 5.11.3; only periodic transfers need to be
 * scheduled in software, this function is only used for such scheduling.
 */
long usb_calc_bus_time (int speed, int is_input, int isoc, int bytecount)
{
	unsigned long	tmp;

	switch (speed) {
	case USB_SPEED_LOW: 	/* INTR only */
		if (is_input) {
			tmp = (67667L * (31L + 10L * BitTime (bytecount))) / 1000L;
			return (64060L + (2 * BW_HUB_LS_SETUP) + BW_HOST_DELAY + tmp);
		} else {
			tmp = (66700L * (31L + 10L * BitTime (bytecount))) / 1000L;
			return (64107L + (2 * BW_HUB_LS_SETUP) + BW_HOST_DELAY + tmp);
		}
	case USB_SPEED_FULL:	/* ISOC or INTR */
		if (isoc) {
			tmp = (8354L * (31L + 10L * BitTime (bytecount))) / 1000L;
			return (((is_input) ? 7268L : 6265L) + BW_HOST_DELAY + tmp);
		} else {
			tmp = (8354L * (31L + 10L * BitTime (bytecount))) / 1000L;
			return (9107L + BW_HOST_DELAY + tmp);
		}
	case USB_SPEED_HIGH:	/* ISOC or INTR */
		// FIXME adjust for input vs output
		if (isoc)
			tmp = HS_USECS (bytecount);
		else
			tmp = HS_USECS_ISO (bytecount);
		return tmp;
	default:
		pr_debug ("%s: bogus device speed!\n", usbcore_name);
		return -1;
	}
}
EXPORT_SYMBOL (usb_calc_bus_time);

/*
 * usb_check_bandwidth():
 *
 * old_alloc is from host_controller->bandwidth_allocated in microseconds;
 * bustime is from calc_bus_time(), but converted to microseconds.
 *
 * returns <bustime in us> if successful,
 * or -ENOSPC if bandwidth request fails.
 *
 * FIXME:
 * This initial implementation does not use Endpoint.bInterval
 * in managing bandwidth allocation.
 * It probably needs to be expanded to use Endpoint.bInterval.
 * This can be done as a later enhancement (correction).
 *
 * This will also probably require some kind of
 * frame allocation tracking...meaning, for example,
 * that if multiple drivers request interrupts every 10 USB frames,
 * they don't all have to be allocated at
 * frame numbers N, N+10, N+20, etc.  Some of them could be at
 * N+11, N+21, N+31, etc., and others at
 * N+12, N+22, N+32, etc.
 *
 * Similarly for isochronous transfers...
 *
 * Individual HCDs can schedule more directly ... this logic
 * is not correct for high speed transfers.
 */
int usb_check_bandwidth (struct usb_device *dev, struct urb *urb)
{
	unsigned int	pipe = urb->pipe;
	long		bustime;
	int		is_in = usb_pipein (pipe);
	int		is_iso = usb_pipeisoc (pipe);
	int		old_alloc = dev->bus->bandwidth_allocated;
	int		new_alloc;


	bustime = NS_TO_US (usb_calc_bus_time (dev->speed, is_in, is_iso,
			usb_maxpacket (dev, pipe, !is_in)));
	if (is_iso)
		bustime /= urb->number_of_packets;

	new_alloc = old_alloc + (int) bustime;
	if (new_alloc > FRAME_TIME_MAX_USECS_ALLOC) {
#ifdef	DEBUG
		char	*mode = 
#ifdef CONFIG_USB_BANDWIDTH
			"";
#else
			"would have ";
#endif
		dev_dbg (&dev->dev, "usb_check_bandwidth %sFAILED: %d + %ld = %d usec\n",
			mode, old_alloc, bustime, new_alloc);
#endif
#ifdef CONFIG_USB_BANDWIDTH
		bustime = -ENOSPC;	/* report error */
#endif
	}

	return bustime;
}
EXPORT_SYMBOL (usb_check_bandwidth);


/**
 * usb_claim_bandwidth - records bandwidth for a periodic transfer
 * @dev: source/target of request
 * @urb: request (urb->dev == dev)
 * @bustime: bandwidth consumed, in (average) microseconds per frame
 * @isoc: true iff the request is isochronous
 *
 * Bus bandwidth reservations are recorded purely for diagnostic purposes.
 * HCDs are expected not to overcommit periodic bandwidth, and to record such
 * reservations whenever endpoints are added to the periodic schedule.
 *
 * FIXME averaging per-frame is suboptimal.  Better to sum over the HCD's
 * entire periodic schedule ... 32 frames for OHCI, 1024 for UHCI, settable
 * for EHCI (256/512/1024 frames, default 1024) and have the bus expose how
 * large its periodic schedule is.
 */
void usb_claim_bandwidth (struct usb_device *dev, struct urb *urb, int bustime, int isoc)
{
	dev->bus->bandwidth_allocated += bustime;
	if (isoc)
		dev->bus->bandwidth_isoc_reqs++;
	else
		dev->bus->bandwidth_int_reqs++;
	urb->bandwidth = bustime;

#ifdef USB_BANDWIDTH_MESSAGES
	dev_dbg (&dev->dev, "bandwidth alloc increased by %d (%s) to %d for %d requesters\n",
		bustime,
		isoc ? "ISOC" : "INTR",
		dev->bus->bandwidth_allocated,
		dev->bus->bandwidth_int_reqs + dev->bus->bandwidth_isoc_reqs);
#endif
}
EXPORT_SYMBOL (usb_claim_bandwidth);


/**
 * usb_release_bandwidth - reverses effect of usb_claim_bandwidth()
 * @dev: source/target of request
 * @urb: request (urb->dev == dev)
 * @isoc: true iff the request is isochronous
 *
 * This records that previously allocated bandwidth has been released.
 * Bandwidth is released when endpoints are removed from the host controller's
 * periodic schedule.
 */
void usb_release_bandwidth (struct usb_device *dev, struct urb *urb, int isoc)
{
	dev->bus->bandwidth_allocated -= urb->bandwidth;
	if (isoc)
		dev->bus->bandwidth_isoc_reqs--;
	else
		dev->bus->bandwidth_int_reqs--;

#ifdef USB_BANDWIDTH_MESSAGES
	dev_dbg (&dev->dev, "bandwidth alloc reduced by %d (%s) to %d for %d requesters\n",
		urb->bandwidth,
		isoc ? "ISOC" : "INTR",
		dev->bus->bandwidth_allocated,
		dev->bus->bandwidth_int_reqs + dev->bus->bandwidth_isoc_reqs);
#endif
	urb->bandwidth = 0;
}
EXPORT_SYMBOL (usb_release_bandwidth);


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

/*
 * Generic HC operations.
 */

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

/* called from khubd, or root hub init threads for hcd-private init */
static int hcd_alloc_dev (struct usb_device *udev)
{
	struct hcd_dev		*dev;
	struct usb_hcd		*hcd;
	unsigned long		flags;

	if (!udev || udev->hcpriv)
		return -EINVAL;
	if (!udev->bus || !udev->bus->hcpriv)
		return -ENODEV;
	hcd = udev->bus->hcpriv;
	if (hcd->state == USB_STATE_QUIESCING)
		return -ENOLINK;

	dev = (struct hcd_dev *) kmalloc (sizeof *dev, GFP_KERNEL);
	if (dev == NULL)
		return -ENOMEM;
	memset (dev, 0, sizeof *dev);

	INIT_LIST_HEAD (&dev->dev_list);
	INIT_LIST_HEAD (&dev->urb_list);

	spin_lock_irqsave (&hcd_data_lock, flags);
	list_add (&dev->dev_list, &hcd->dev_list);
	// refcount is implicit
	udev->hcpriv = dev;
	spin_unlock_irqrestore (&hcd_data_lock, flags);

	return 0;
}

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

static void urb_unlink (struct urb *urb)
{
	unsigned long		flags;

	/* Release any periodic transfer bandwidth */
	if (urb->bandwidth)
		usb_release_bandwidth (urb->dev, urb,
			usb_pipeisoc (urb->pipe));

	/* clear all state linking urb to this dev (and hcd) */

	spin_lock_irqsave (&hcd_data_lock, flags);
	list_del_init (&urb->urb_list);
	spin_unlock_irqrestore (&hcd_data_lock, flags);
	usb_put_dev (urb->dev);
}


/* may be called in any context with a valid urb->dev usecount
 * caller surrenders "ownership" of urb
 * expects usb_submit_urb() to have sanity checked and conditioned all
 * inputs in the urb
 */
static int hcd_submit_urb (struct urb *urb, int mem_flags)
{
	int			status;
	struct usb_hcd		*hcd = urb->dev->bus->hcpriv;
	struct hcd_dev		*dev = urb->dev->hcpriv;
	unsigned long		flags;

	if (!hcd || !dev)
		return -ENODEV;

	/*
	 * FIXME:  make urb timeouts be generic, keeping the HCD cores
	 * as simple as possible.
	 */

	// NOTE:  a generic device/urb monitoring hook would go here.
	// hcd_monitor_hook(MONITOR_URB_SUBMIT, urb)
	// It would catch submission paths for all urbs.

	/*
	 * Atomically queue the urb,  first to our records, then to the HCD.
	 * Access to urb->status is controlled by urb->lock ... changes on
	 * i/o completion (normal or fault) or unlinking.
	 */

	// FIXME:  verify that quiescing hc works right (RH cleans up)

	spin_lock_irqsave (&hcd_data_lock, flags);
	if (unlikely (urb->reject))
		status = -EPERM;
	else if (HCD_IS_RUNNING (hcd->state) &&
			hcd->state != USB_STATE_QUIESCING) {
		usb_get_dev (urb->dev);
		list_add_tail (&urb->urb_list, &dev->urb_list);
		status = 0;
	} else
		status = -ESHUTDOWN;
	spin_unlock_irqrestore (&hcd_data_lock, flags);
	if (status) {
		INIT_LIST_HEAD (&urb->urb_list);
		return status;
	}

	/* increment urb's reference count as part of giving it to the HCD
	 * (which now controls it).  HCD guarantees that it either returns
	 * an error or calls giveback(), but not both.
	 */
	urb = usb_get_urb (urb);
	atomic_inc (&urb->use_count);

	if (urb->dev == hcd->self.root_hub) {
		/* NOTE:  requirement on hub callers (usbfs and the hub
		 * driver, for now) that URBs' urb->transfer_buffer be
		 * valid and usb_buffer_{sync,unmap}() not be needed, since
		 * they could clobber root hub response data.
		 */
		urb->transfer_flags |= (URB_NO_TRANSFER_DMA_MAP
					| URB_NO_SETUP_DMA_MAP);
		status = rh_urb_enqueue (hcd, urb);
		goto done;
	}

	/* lower level hcd code should use *_dma exclusively,
	 * unless it uses pio or talks to another transport.
	 */
	if (hcd->self.controller->dma_mask) {
		if (usb_pipecontrol (urb->pipe)
			&& !(urb->transfer_flags & URB_NO_SETUP_DMA_MAP))
			urb->setup_dma = dma_map_single (
					hcd->self.controller,
					urb->setup_packet,
					sizeof (struct usb_ctrlrequest),
					DMA_TO_DEVICE);
		if (urb->transfer_buffer_length != 0
			&& !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP))
			urb->transfer_dma = dma_map_single (
					hcd->self.controller,
					urb->transfer_buffer,
					urb->transfer_buffer_length,
					usb_pipein (urb->pipe)
					    ? DMA_FROM_DEVICE
					    : DMA_TO_DEVICE);
	}

	status = hcd->driver->urb_enqueue (hcd, urb, mem_flags);
done:
	if (unlikely (status)) {
		urb_unlink (urb);
		atomic_dec (&urb->use_count);
		if (urb->reject)
			wake_up (&usb_kill_urb_queue);
		usb_put_urb (urb);
	}
	return status;
}

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

/* called in any context */
static int hcd_get_frame_number (struct usb_device *udev)
{
	struct usb_hcd	*hcd = (struct usb_hcd *)udev->bus->hcpriv;
	if (!HCD_IS_RUNNING (hcd->state))
		return -ESHUTDOWN;
	return hcd->driver->get_frame_number (hcd);
}

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

/* this makes the hcd giveback() the urb more quickly, by kicking it
 * off hardware queues (which may take a while) and returning it as
 * soon as practical.  we've already set up the urb's return status,
 * but we can't know if the callback completed already.
 */
static int
unlink1 (struct usb_hcd *hcd, struct urb *urb)
{
	int		value;

	if (urb == (struct urb *) hcd->rh_timer.data)
		value = usb_rh_status_dequeue (hcd, urb);
	else {

		/* The only reason an HCD might fail this call is if
		 * it has not yet fully queued the urb to begin with.
		 * Such failures should be harmless. */
		value = hcd->driver->urb_dequeue (hcd, urb);
	}

	if (value != 0)
		dev_dbg (hcd->self.controller, "dequeue %p --> %d\n",
				urb, value);
	return value;
}

/*
 * called in any context
 *
 * caller guarantees urb won't be recycled till both unlink()
 * and the urb's completion function return
 */
static int hcd_unlink_urb (struct urb *urb, int status)
{
	struct hcd_dev			*dev;
	struct usb_hcd			*hcd = NULL;
	struct device			*sys = NULL;
	unsigned long			flags;
	struct list_head		*tmp;
	int				retval;

	if (!urb)
		return -EINVAL;

	/*
	 * we contend for urb->status with the hcd core,
	 * which changes it while returning the urb.
	 *
	 * Caller guaranteed that the urb pointer hasn't been freed, and
	 * that it was submitted.  But as a rule it can't know whether or
	 * not it's already been unlinked ... so we respect the reversed
	 * lock sequence needed for the usb_hcd_giveback_urb() code paths
	 * (urb lock, then hcd_data_lock) in case some other CPU is now
	 * unlinking it.