ehci-sched.c

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	//   qh->hw_info1 |= __constant_cpu_to_le32 (1 << 7 /* "ignore" */);

	/* high bandwidth, or otherwise part of every microframe */
	if ((period = qh->period) == 0)
		period = 1;

	for (i = qh->start; i < ehci->periodic_size; i += period)
		periodic_unlink (ehci, i, qh);

	/* update per-qh bandwidth for usbfs */
	ehci_to_hcd(ehci)->self.bandwidth_allocated -= qh->period
		? ((qh->usecs + qh->c_usecs) / qh->period)
		: (qh->usecs * 8);

	dev_dbg (&qh->dev->dev,
		"unlink qh%d-%04x/%p start %d [%d/%d us]\n",
		qh->period,
		le32_to_cpup (&qh->hw_info2) & (QH_CMASK | QH_SMASK),
		qh, qh->start, qh->usecs, qh->c_usecs);

	/* qh->qh_next still "live" to HC */
	qh->qh_state = QH_STATE_UNLINK;
	qh->qh_next.ptr = NULL;
	qh_put (qh);

	/* maybe turn off periodic schedule */
	ehci->periodic_sched--;
	if (!ehci->periodic_sched)
		(void) disable_periodic (ehci);
}

static void intr_deschedule (struct ehci_hcd *ehci, struct ehci_qh *qh)
{
	unsigned	wait;

	qh_unlink_periodic (ehci, qh);

	/* simple/paranoid:  always delay, expecting the HC needs to read
	 * qh->hw_next or finish a writeback after SPLIT/CSPLIT ... and
	 * expect khubd to clean up after any CSPLITs we won't issue.
	 * active high speed queues may need bigger delays...
	 */
	if (list_empty (&qh->qtd_list)
			|| (__constant_cpu_to_le32 (QH_CMASK)
					& qh->hw_info2) != 0)
		wait = 2;
	else
		wait = 55;	/* worst case: 3 * 1024 */

	udelay (wait);
	qh->qh_state = QH_STATE_IDLE;
	qh->hw_next = EHCI_LIST_END;
	wmb ();
}

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

static int check_period (
	struct ehci_hcd *ehci,
	unsigned	frame,
	unsigned	uframe,
	unsigned	period,
	unsigned	usecs
) {
	int		claimed;

	/* complete split running into next frame?
	 * given FSTN support, we could sometimes check...
	 */
	if (uframe >= 8)
		return 0;

	/*
	 * 80% periodic == 100 usec/uframe available
	 * convert "usecs we need" to "max already claimed"
	 */
	usecs = 100 - usecs;

	/* we "know" 2 and 4 uframe intervals were rejected; so
	 * for period 0, check _every_ microframe in the schedule.
	 */
	if (unlikely (period == 0)) {
		do {
			for (uframe = 0; uframe < 7; uframe++) {
				claimed = periodic_usecs (ehci, frame, uframe);
				if (claimed > usecs)
					return 0;
			}
		} while ((frame += 1) < ehci->periodic_size);

	/* just check the specified uframe, at that period */
	} else {
		do {
			claimed = periodic_usecs (ehci, frame, uframe);
			if (claimed > usecs)
				return 0;
		} while ((frame += period) < ehci->periodic_size);
	}

	// success!
	return 1;
}

static int check_intr_schedule (
	struct ehci_hcd		*ehci,
	unsigned		frame,
	unsigned		uframe,
	const struct ehci_qh	*qh,
	__le32			*c_maskp
)
{
	int		retval = -ENOSPC;
	u8		mask = 0;

	if (qh->c_usecs && uframe >= 6)		/* FSTN territory? */
		goto done;

	if (!check_period (ehci, frame, uframe, qh->period, qh->usecs))
		goto done;
	if (!qh->c_usecs) {
		retval = 0;
		*c_maskp = 0;
		goto done;
	}

#ifdef CONFIG_USB_EHCI_TT_NEWSCHED
	if (tt_available (ehci, qh->period, qh->dev, frame, uframe,
				qh->tt_usecs)) {
		unsigned i;

		/* TODO : this may need FSTN for SSPLIT in uframe 5. */
		for (i=uframe+1; i<8 && i<uframe+4; i++)
			if (!check_period (ehci, frame, i,
						qh->period, qh->c_usecs))
				goto done;
			else
				mask |= 1 << i;

		retval = 0;

		*c_maskp = cpu_to_le32 (mask << 8);
	}
#else
	/* Make sure this tt's buffer is also available for CSPLITs.
	 * We pessimize a bit; probably the typical full speed case
	 * doesn't need the second CSPLIT.
	 *
	 * NOTE:  both SPLIT and CSPLIT could be checked in just
	 * one smart pass...
	 */
	mask = 0x03 << (uframe + qh->gap_uf);
	*c_maskp = cpu_to_le32 (mask << 8);

	mask |= 1 << uframe;
	if (tt_no_collision (ehci, qh->period, qh->dev, frame, mask)) {
		if (!check_period (ehci, frame, uframe + qh->gap_uf + 1,
					qh->period, qh->c_usecs))
			goto done;
		if (!check_period (ehci, frame, uframe + qh->gap_uf,
					qh->period, qh->c_usecs))
			goto done;
		retval = 0;
	}
#endif
done:
	return retval;
}

/* "first fit" scheduling policy used the first time through,
 * or when the previous schedule slot can't be re-used.
 */
static int qh_schedule (struct ehci_hcd *ehci, struct ehci_qh *qh)
{
	int		status;
	unsigned	uframe;
	__le32		c_mask;
	unsigned	frame;		/* 0..(qh->period - 1), or NO_FRAME */

	qh_refresh(ehci, qh);
	qh->hw_next = EHCI_LIST_END;
	frame = qh->start;

	/* reuse the previous schedule slots, if we can */
	if (frame < qh->period) {
		uframe = ffs (le32_to_cpup (&qh->hw_info2) & QH_SMASK);
		status = check_intr_schedule (ehci, frame, --uframe,
				qh, &c_mask);
	} else {
		uframe = 0;
		c_mask = 0;
		status = -ENOSPC;
	}

	/* else scan the schedule to find a group of slots such that all
	 * uframes have enough periodic bandwidth available.
	 */
	if (status) {
		/* "normal" case, uframing flexible except with splits */
		if (qh->period) {
			frame = qh->period - 1;
			do {
				for (uframe = 0; uframe < 8; uframe++) {
					status = check_intr_schedule (ehci,
							frame, uframe, qh,
							&c_mask);
					if (status == 0)
						break;
				}
			} while (status && frame--);

		/* qh->period == 0 means every uframe */
		} else {
			frame = 0;
			status = check_intr_schedule (ehci, 0, 0, qh, &c_mask);
		}
		if (status)
			goto done;
		qh->start = frame;

		/* reset S-frame and (maybe) C-frame masks */
		qh->hw_info2 &= __constant_cpu_to_le32(~(QH_CMASK | QH_SMASK));
		qh->hw_info2 |= qh->period
			? cpu_to_le32 (1 << uframe)
			: __constant_cpu_to_le32 (QH_SMASK);
		qh->hw_info2 |= c_mask;
	} else
		ehci_dbg (ehci, "reused qh %p schedule\n", qh);

	/* stuff into the periodic schedule */
	status = qh_link_periodic (ehci, qh);
done:
	return status;
}

static int intr_submit (
	struct ehci_hcd		*ehci,
	struct usb_host_endpoint *ep,
	struct urb		*urb,
	struct list_head	*qtd_list,
	gfp_t			mem_flags
) {
	unsigned		epnum;
	unsigned long		flags;
	struct ehci_qh		*qh;
	int			status = 0;
	struct list_head	empty;

	/* get endpoint and transfer/schedule data */
	epnum = ep->desc.bEndpointAddress;

	spin_lock_irqsave (&ehci->lock, flags);

	if (unlikely(!test_bit(HCD_FLAG_HW_ACCESSIBLE,
			       &ehci_to_hcd(ehci)->flags))) {
		status = -ESHUTDOWN;
		goto done;
	}

	/* get qh and force any scheduling errors */
	INIT_LIST_HEAD (&empty);
	qh = qh_append_tds (ehci, urb, &empty, epnum, &ep->hcpriv);
	if (qh == NULL) {
		status = -ENOMEM;
		goto done;
	}
	if (qh->qh_state == QH_STATE_IDLE) {
		if ((status = qh_schedule (ehci, qh)) != 0)
			goto done;
	}

	/* then queue the urb's tds to the qh */
	qh = qh_append_tds (ehci, urb, qtd_list, epnum, &ep->hcpriv);
	BUG_ON (qh == NULL);

	/* ... update usbfs periodic stats */
	ehci_to_hcd(ehci)->self.bandwidth_int_reqs++;

done:
	spin_unlock_irqrestore (&ehci->lock, flags);
	if (status)
		qtd_list_free (ehci, urb, qtd_list);

	return status;
}

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

/* ehci_iso_stream ops work with both ITD and SITD */

static struct ehci_iso_stream *
iso_stream_alloc (gfp_t mem_flags)
{
	struct ehci_iso_stream *stream;

	stream = kzalloc(sizeof *stream, mem_flags);
	if (likely (stream != NULL)) {
		INIT_LIST_HEAD(&stream->td_list);
		INIT_LIST_HEAD(&stream->free_list);
		stream->next_uframe = -1;
		stream->refcount = 1;
	}
	return stream;
}

static void
iso_stream_init (
	struct ehci_hcd		*ehci,
	struct ehci_iso_stream	*stream,
	struct usb_device	*dev,
	int			pipe,
	unsigned		interval
)
{
	static const u8 smask_out [] = { 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f };

	u32			buf1;
	unsigned		epnum, maxp;
	int			is_input;
	long			bandwidth;

	/*
	 * this might be a "high bandwidth" highspeed endpoint,
	 * as encoded in the ep descriptor's wMaxPacket field
	 */
	epnum = usb_pipeendpoint (pipe);
	is_input = usb_pipein (pipe) ? USB_DIR_IN : 0;
	maxp = usb_maxpacket(dev, pipe, !is_input);
	if (is_input) {
		buf1 = (1 << 11);
	} else {
		buf1 = 0;
	}

	/* knows about ITD vs SITD */
	if (dev->speed == USB_SPEED_HIGH) {
		unsigned multi = hb_mult(maxp);

		stream->highspeed = 1;

		maxp = max_packet(maxp);
		buf1 |= maxp;
		maxp *= multi;

		stream->buf0 = cpu_to_le32 ((epnum << 8) | dev->devnum);
		stream->buf1 = cpu_to_le32 (buf1);
		stream->buf2 = cpu_to_le32 (multi);

		/* usbfs wants to report the average usecs per frame tied up
		 * when transfers on this endpoint are scheduled ...
		 */
		stream->usecs = HS_USECS_ISO (maxp);
		bandwidth = stream->usecs * 8;
		bandwidth /= 1 << (interval - 1);

	} else {
		u32		addr;
		int		think_time;
		int		hs_transfers;

		addr = dev->ttport << 24;
		if (!ehci_is_TDI(ehci)
				|| (dev->tt->hub !=
					ehci_to_hcd(ehci)->self.root_hub))
			addr |= dev->tt->hub->devnum << 16;
		addr |= epnum << 8;
		addr |= dev->devnum;
		stream->usecs = HS_USECS_ISO (maxp);
		think_time = dev->tt ? dev->tt->think_time : 0;
		stream->tt_usecs = NS_TO_US (think_time + usb_calc_bus_time (
				dev->speed, is_input, 1, maxp));
		hs_transfers = max (1u, (maxp + 187) / 188);
		if (is_input) {
			u32	tmp;

			addr |= 1 << 31;
			stream->c_usecs = stream->usecs;
			stream->usecs = HS_USECS_ISO (1);
			stream->raw_mask = 1;

			/* c-mask as specified in USB 2.0 11.18.4 3.c */
			tmp = (1 << (hs_transfers + 2)) - 1;
			stream->raw_mask |= tmp << (8 + 2);
		} else
			stream->raw_mask = smask_out [hs_transfers - 1];
		bandwidth = stream->usecs + stream->c_usecs;
		bandwidth /= 1 << (interval + 2);

		/* stream->splits gets created from raw_mask later */
		stream->address = cpu_to_le32 (addr);
	}
	stream->bandwidth = bandwidth;

	stream->udev = dev;

	stream->bEndpointAddress = is_input | epnum;
	stream->interval = interval;
	stream->maxp = maxp;
}

static void
iso_stream_put(struct ehci_hcd *ehci, struct ehci_iso_stream *stream)
{
	stream->refcount--;

	/* free whenever just a dev->ep reference remains.
	 * not like a QH -- no persistent state (toggle, halt)
	 */
	if (stream->refcount == 1) {
		int		is_in;

		// BUG_ON (!list_empty(&stream->td_list));

		while (!list_empty (&stream->free_list)) {
			struct list_head	*entry;

			entry = stream->free_list.next;
			list_del (entry);

			/* knows about ITD vs SITD */
			if (stream->highspeed) {
				struct ehci_itd		*itd;

				itd = list_entry (entry, struct ehci_itd,
						itd_list);
				dma_pool_free (ehci->itd_pool, itd,
						itd->itd_dma);
			} else {
				struct ehci_sitd	*sitd;

				sitd = list_entry (entry, struct ehci_sitd,
						sitd_list);
				dma_pool_free (ehci->sitd_pool, sitd,
						sitd->sitd_dma);
			}
		}

		is_in = (stream->bEndpointAddress & USB_DIR_IN) ? 0x10 : 0;
		stream->bEndpointAddress &= 0x0f;
		stream->ep->hcpriv = NULL;

		if (stream->rescheduled) {
			ehci_info (ehci, "ep%d%s-iso rescheduled "
				"%lu times in %lu seconds\n",
				stream->bEndpointAddress, is_in ? "in" : "out",
				stream->rescheduled,
				((jiffies - stream->start)/HZ)
				);
		}

		kfree(stream);
	}
}

static inline struct ehci_iso_stream *
iso_stream_get (struct ehci_iso_stream *stream)
{
	if (likely (stream != NULL))
		stream->refcount++;
	return stream;
}

static struct ehci_iso_stream *
iso_stream_find (struct ehci_hcd *ehci, struct urb *urb)
{
	unsigned		epnum;
	struct ehci_iso_stream	*stream;
	struct usb_host_endpoint *ep;
	unsigned long		flags;

	epnum = usb_pipeendpoint (urb->pipe);
	if (usb_pipein(urb->pipe))
		ep = urb->dev->ep_in[epnum];
	else
		ep = urb->dev->ep_out[epnum];

	spin_lock_irqsave (&ehci->lock, flags);
	stream = ep->hcpriv;

	if (unlikely (stream == NULL)) {
		stream = iso_stream_alloc(GFP_ATOMIC);
		if (likely (stream != NULL)) {
			/* dev->ep owns the initial refcount */
			ep->hcpriv = stream;
			stream->ep = ep;
			iso_stream_init(ehci, stream, urb->dev, urb->pipe,
					urb->interval);
		}

	/* if dev->ep [epnum] is a QH, info1.maxpacket is nonzero */
	} else if (unlikely (stream->hw_info1 != 0)) {
		ehci_dbg (ehci, "dev %s ep%d%s, not iso??\n",
			urb->dev->devpath, epnum,
			usb_pipein(urb->pipe) ? "in" : "out");
		stream = NULL;
	}

	/* caller guarantees an eventual matching iso_stream_put */
	stream = iso_stream_get (stream);

	spin_unlock_irqrestore (&ehci->lock, flags);
	return stream;
}

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

/* ehci_iso_sched ops can be ITD-only or SITD-only */

static struct ehci_iso_sched *
iso_sched_alloc (unsigned packets, gfp_t mem_flags)
{
	struct ehci_iso_sched	*iso_sched;
	int			size = sizeof *iso_sched;

	size += packets * sizeof (struct ehci_iso_packet);
	iso_sched = kzalloc(size, mem_flags);
	if (likely (iso_sched != NULL)) {
		INIT_LIST_HEAD (&iso_sched->td_list);
	}
	return iso_sched;
}

static inline void
itd_sched_init (
	struct ehci_iso_sched	*iso_sched,
	struct ehci_iso_stream	*stream,
	struct urb		*urb
)
{
	unsigned	i;
	dma_addr_t	dma = urb->transfer_dma;

	/* how many uframes are needed for these transfers */
	iso_sched->span = urb->number_of_packets * stream->interval;

	/* figure out per-uframe itd fields that we'll need later
	 * when we fit new itds into the schedule.
	 */
	for (i = 0; i < urb->number_of_packets; i++) {
		struct ehci_iso_packet	*uframe = &iso_sched->packet [i];
		unsigned		length;
		dma_addr_t		buf;
		u32			trans;

		length = urb->iso_frame_desc [i].length;
		buf = dma + urb->iso_frame_desc [i].offset;

		trans = EHCI_ISOC_ACTIVE;
		trans |= buf & 0x0fff;
		if (unlikely (((i + 1) == urb->number_of_packets))
				&& !(urb->transfer_flags & URB_NO_INTERRUPT))
			trans |= EHCI_ITD_IOC;
		trans |= length << 16;
		uframe->transaction = cpu_to_le32 (trans);

		/* might need to cross a buffer page within a uframe */
		uframe->bufp = (buf & ~(u64)0x0fff);
		buf += length;