ehci-sched.c

底层驱动开发

			trans |= SITD_IOC;
		trans |= length << 16;
		packet->transaction = cpu_to_le32 (trans);

		/* might need to cross a buffer page within a td */
		packet->bufp = buf;
		packet->buf1 = (buf + length) & ~0x0fff;
		if (packet->buf1 != (buf & ~(u64)0x0fff))
			packet->cross = 1;

		/* OUT uses multiple start-splits */ 
		if (stream->bEndpointAddress & USB_DIR_IN)
			continue;
		length = (length + 187) / 188;
		if (length > 1) /* BEGIN vs ALL */
			length |= 1 << 3;
		packet->buf1 |= length;
	}
}

static int
sitd_urb_transaction (
	struct ehci_iso_stream	*stream,
	struct ehci_hcd		*ehci,
	struct urb		*urb,
	unsigned		mem_flags
)
{
	struct ehci_sitd	*sitd;
	dma_addr_t		sitd_dma;
	int			i;
	struct ehci_iso_sched	*iso_sched;
	unsigned long		flags;

	iso_sched = iso_sched_alloc (urb->number_of_packets, mem_flags);
	if (iso_sched == NULL)
		return -ENOMEM;

	sitd_sched_init (iso_sched, stream, urb);

	/* allocate/init sITDs */
	spin_lock_irqsave (&ehci->lock, flags);
	for (i = 0; i < urb->number_of_packets; i++) {

		/* NOTE:  for now, we don't try to handle wraparound cases
		 * for IN (using sitd->hw_backpointer, like a FSTN), which
		 * means we never need two sitds for full speed packets.
		 */

		/* free_list.next might be cache-hot ... but maybe
		 * the HC caches it too. avoid that issue for now.
		 */

		/* prefer previously-allocated sitds */
		if (!list_empty(&stream->free_list)) {
			sitd = list_entry (stream->free_list.prev,
					 struct ehci_sitd, sitd_list);
			list_del (&sitd->sitd_list);
			sitd_dma = sitd->sitd_dma;
		} else
			sitd = NULL;

		if (!sitd) {
			spin_unlock_irqrestore (&ehci->lock, flags);
			sitd = dma_pool_alloc (ehci->sitd_pool, mem_flags,
					&sitd_dma);
			spin_lock_irqsave (&ehci->lock, flags);
		}

		if (!sitd) {
			iso_sched_free (stream, iso_sched);
			spin_unlock_irqrestore (&ehci->lock, flags);
			return -ENOMEM;
		}
		memset (sitd, 0, sizeof *sitd);
		sitd->sitd_dma = sitd_dma;
		list_add (&sitd->sitd_list, &iso_sched->td_list);
	}

	/* temporarily store schedule info in hcpriv */
	urb->hcpriv = iso_sched;
	urb->error_count = 0;

	spin_unlock_irqrestore (&ehci->lock, flags);
	return 0;
}

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

static inline void
sitd_patch (
	struct ehci_iso_stream	*stream,
	struct ehci_sitd	*sitd,
	struct ehci_iso_sched	*iso_sched,
	unsigned		index
)
{
	struct ehci_iso_packet	*uf = &iso_sched->packet [index];
	u64			bufp = uf->bufp;

	sitd->hw_next = EHCI_LIST_END;
	sitd->hw_fullspeed_ep = stream->address;
	sitd->hw_uframe = stream->splits;
	sitd->hw_results = uf->transaction;
	sitd->hw_backpointer = EHCI_LIST_END;

	bufp = uf->bufp;
	sitd->hw_buf [0] = cpu_to_le32 (bufp);
	sitd->hw_buf_hi [0] = cpu_to_le32 (bufp >> 32);

	sitd->hw_buf [1] = cpu_to_le32 (uf->buf1);
	if (uf->cross)
		bufp += 4096;
	sitd->hw_buf_hi [1] = cpu_to_le32 (bufp >> 32);
	sitd->index = index;
}

static inline void
sitd_link (struct ehci_hcd *ehci, unsigned frame, struct ehci_sitd *sitd)
{
	/* note: sitd ordering could matter (CSPLIT then SSPLIT) */
	sitd->sitd_next = ehci->pshadow [frame];
	sitd->hw_next = ehci->periodic [frame];
	ehci->pshadow [frame].sitd = sitd;
	sitd->frame = frame;
	wmb ();
	ehci->periodic [frame] = cpu_to_le32 (sitd->sitd_dma) | Q_TYPE_SITD;
}

/* fit urb's sitds into the selected schedule slot; activate as needed */
static int
sitd_link_urb (
	struct ehci_hcd		*ehci,
	struct urb		*urb,
	unsigned		mod,
	struct ehci_iso_stream	*stream
)
{
	int			packet;
	unsigned		next_uframe;
	struct ehci_iso_sched	*sched = urb->hcpriv;
	struct ehci_sitd	*sitd;

	next_uframe = stream->next_uframe;

	if (list_empty(&stream->td_list)) {
		/* usbfs ignores TT bandwidth */
		ehci_to_hcd(ehci)->self.bandwidth_allocated
				+= stream->bandwidth;
		ehci_vdbg (ehci,
			"sched devp %s ep%d%s-iso [%d] %dms/%04x\n",
			urb->dev->devpath, stream->bEndpointAddress & 0x0f,
			(stream->bEndpointAddress & USB_DIR_IN) ? "in" : "out",
			(next_uframe >> 3) % ehci->periodic_size,
			stream->interval, le32_to_cpu (stream->splits));
		stream->start = jiffies;
	}
	ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs++;

	/* fill sITDs frame by frame */
	for (packet = 0, sitd = NULL;
			packet < urb->number_of_packets;
			packet++) {

		/* ASSERT:  we have all necessary sitds */
		BUG_ON (list_empty (&sched->td_list));

		/* ASSERT:  no itds for this endpoint in this frame */

		sitd = list_entry (sched->td_list.next,
				struct ehci_sitd, sitd_list);
		list_move_tail (&sitd->sitd_list, &stream->td_list);
		sitd->stream = iso_stream_get (stream);
		sitd->urb = usb_get_urb (urb);

		sitd_patch (stream, sitd, sched, packet);
		sitd_link (ehci, (next_uframe >> 3) % ehci->periodic_size,
				sitd);

		next_uframe += stream->interval << 3;
		stream->depth += stream->interval << 3;
	}
	stream->next_uframe = next_uframe % mod;

	/* don't need that schedule data any more */
	iso_sched_free (stream, sched);
	urb->hcpriv = NULL;

	timer_action (ehci, TIMER_IO_WATCHDOG);
	if (!ehci->periodic_sched++)
		return enable_periodic (ehci);
	return 0;
}

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

#define	SITD_ERRS (SITD_STS_ERR | SITD_STS_DBE | SITD_STS_BABBLE \
	       			| SITD_STS_XACT | SITD_STS_MMF)

static unsigned
sitd_complete (
	struct ehci_hcd		*ehci,
	struct ehci_sitd	*sitd,
	struct pt_regs		*regs
) {
	struct urb				*urb = sitd->urb;
	struct usb_iso_packet_descriptor	*desc;
	u32					t;
	int					urb_index = -1;
	struct ehci_iso_stream			*stream = sitd->stream;
	struct usb_device			*dev;

	urb_index = sitd->index;
	desc = &urb->iso_frame_desc [urb_index];
	t = le32_to_cpup (&sitd->hw_results);

	/* report transfer status */
	if (t & SITD_ERRS) {
		urb->error_count++;
		if (t & SITD_STS_DBE)
			desc->status = usb_pipein (urb->pipe)
				? -ENOSR  /* hc couldn't read */
				: -ECOMM; /* hc couldn't write */
		else if (t & SITD_STS_BABBLE)
			desc->status = -EOVERFLOW;
		else /* XACT, MMF, etc */
			desc->status = -EPROTO;
	} else {
		desc->status = 0;
		desc->actual_length = desc->length - SITD_LENGTH (t);
	}

	usb_put_urb (urb);
	sitd->urb = NULL;
	sitd->stream = NULL;
	list_move (&sitd->sitd_list, &stream->free_list);
	stream->depth -= stream->interval << 3;
	iso_stream_put (ehci, stream);

	/* handle completion now? */
	if ((urb_index + 1) != urb->number_of_packets)
		return 0;

	/* ASSERT: it's really the last sitd for this urb
	list_for_each_entry (sitd, &stream->td_list, sitd_list)
		BUG_ON (sitd->urb == urb);
	 */

	/* give urb back to the driver */
	dev = usb_get_dev (urb->dev);
	ehci_urb_done (ehci, urb, regs);
	urb = NULL;

	/* defer stopping schedule; completion can submit */
	ehci->periodic_sched--;
	if (!ehci->periodic_sched)
		(void) disable_periodic (ehci);
	ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs--;

	if (list_empty (&stream->td_list)) {
		ehci_to_hcd(ehci)->self.bandwidth_allocated
				-= stream->bandwidth;
		ehci_vdbg (ehci,
			"deschedule devp %s ep%d%s-iso\n",
			dev->devpath, stream->bEndpointAddress & 0x0f,
			(stream->bEndpointAddress & USB_DIR_IN) ? "in" : "out");
	}
	iso_stream_put (ehci, stream);
	usb_put_dev (dev);

	return 1;
}


static int sitd_submit (struct ehci_hcd *ehci, struct urb *urb,
	unsigned mem_flags)
{
	int			status = -EINVAL;
	unsigned long		flags;
	struct ehci_iso_stream	*stream;

	/* Get iso_stream head */
	stream = iso_stream_find (ehci, urb);
	if (stream == NULL) {
		ehci_dbg (ehci, "can't get iso stream\n");
		return -ENOMEM;
	}
	if (urb->interval != stream->interval) {
		ehci_dbg (ehci, "can't change iso interval %d --> %d\n",
			stream->interval, urb->interval);
		goto done;
	}

#ifdef EHCI_URB_TRACE
	ehci_dbg (ehci,
		"submit %p dev%s ep%d%s-iso len %d\n",
		urb, urb->dev->devpath,
		usb_pipeendpoint (urb->pipe),
		usb_pipein (urb->pipe) ? "in" : "out",
		urb->transfer_buffer_length);
#endif

	/* allocate SITDs */
	status = sitd_urb_transaction (stream, ehci, urb, mem_flags);
	if (status < 0) {
		ehci_dbg (ehci, "can't init sitds\n");
		goto done;
	}

	/* schedule ... need to lock */
	spin_lock_irqsave (&ehci->lock, flags);
	status = iso_stream_schedule (ehci, urb, stream);
 	if (status == 0)
		sitd_link_urb (ehci, urb, ehci->periodic_size << 3, stream);
	spin_unlock_irqrestore (&ehci->lock, flags);

done:
	if (status < 0)
		iso_stream_put (ehci, stream);
	return status;
}

#else

static inline int
sitd_submit (struct ehci_hcd *ehci, struct urb *urb,
	unsigned mem_flags)
{
	ehci_dbg (ehci, "split iso support is disabled\n");
	return -ENOSYS;
}

static inline unsigned
sitd_complete (
	struct ehci_hcd		*ehci,
	struct ehci_sitd	*sitd,
	struct pt_regs		*regs
) {
	ehci_err (ehci, "sitd_complete %p?\n", sitd);
	return 0;
}

#endif /* USB_EHCI_SPLIT_ISO */

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

static void
scan_periodic (struct ehci_hcd *ehci, struct pt_regs *regs)
{
	unsigned	frame, clock, now_uframe, mod;
	unsigned	modified;

	mod = ehci->periodic_size << 3;

	/*
	 * When running, scan from last scan point up to "now"
	 * else clean up by scanning everything that's left.
	 * Touches as few pages as possible:  cache-friendly.
	 */
	now_uframe = ehci->next_uframe;
	if (HC_IS_RUNNING (ehci_to_hcd(ehci)->state))
		clock = readl (&ehci->regs->frame_index);
	else
		clock = now_uframe + mod - 1;
	clock %= mod;

	for (;;) {
		union ehci_shadow	q, *q_p;
		__le32			type, *hw_p;
		unsigned		uframes;

		/* don't scan past the live uframe */
		frame = now_uframe >> 3;
		if (frame == (clock >> 3))
			uframes = now_uframe & 0x07;
		else {
			/* safe to scan the whole frame at once */
			now_uframe |= 0x07;
			uframes = 8;
		}

restart:
		/* scan each element in frame's queue for completions */
		q_p = &ehci->pshadow [frame];
		hw_p = &ehci->periodic [frame];
		q.ptr = q_p->ptr;
		type = Q_NEXT_TYPE (*hw_p);
		modified = 0;

		while (q.ptr != NULL) {
			unsigned		uf;
			union ehci_shadow	temp;
			int			live;

			live = HC_IS_RUNNING (ehci_to_hcd(ehci)->state);
			switch (type) {
			case Q_TYPE_QH:
				/* handle any completions */
				temp.qh = qh_get (q.qh);
				type = Q_NEXT_TYPE (q.qh->hw_next);
				q = q.qh->qh_next;
				modified = qh_completions (ehci, temp.qh, regs);
				if (unlikely (list_empty (&temp.qh->qtd_list)))
					intr_deschedule (ehci, temp.qh);
				qh_put (temp.qh);
				break;
			case Q_TYPE_FSTN:
				/* for "save place" FSTNs, look at QH entries
				 * in the previous frame for completions.
				 */
				if (q.fstn->hw_prev != EHCI_LIST_END) {
					dbg ("ignoring completions from FSTNs");
				}
				type = Q_NEXT_TYPE (q.fstn->hw_next);
				q = q.fstn->fstn_next;
				break;
			case Q_TYPE_ITD:
				/* skip itds for later in the frame */
				rmb ();
				for (uf = live ? uframes : 8; uf < 8; uf++) {
					if (0 == (q.itd->hw_transaction [uf]
							& ITD_ACTIVE))
						continue;
					q_p = &q.itd->itd_next;
					hw_p = &q.itd->hw_next;
					type = Q_NEXT_TYPE (q.itd->hw_next);
					q = *q_p;
					break;
				}
				if (uf != 8)
					break;

				/* this one's ready ... HC won't cache the
				 * pointer for much longer, if at all.
				 */
				*q_p = q.itd->itd_next;
				*hw_p = q.itd->hw_next;
				type = Q_NEXT_TYPE (q.itd->hw_next);
				wmb();
				modified = itd_complete (ehci, q.itd, regs);
				q = *q_p;
				break;
			case Q_TYPE_SITD:
				if ((q.sitd->hw_results & SITD_ACTIVE)
						&& live) {
					q_p = &q.sitd->sitd_next;
					hw_p = &q.sitd->hw_next;
					type = Q_NEXT_TYPE (q.sitd->hw_next);
					q = *q_p;
					break;
				}
				*q_p = q.sitd->sitd_next;
				*hw_p = q.sitd->hw_next;
				type = Q_NEXT_TYPE (q.sitd->hw_next);
				wmb();
				modified = sitd_complete (ehci, q.sitd, regs);
				q = *q_p;
				break;
			default:
				dbg ("corrupt type %d frame %d shadow %p",
					type, frame, q.ptr);
				// BUG ();
				q.ptr = NULL;
			}

			/* assume completion callbacks modify the queue */
			if (unlikely (modified))
				goto restart;
		}

		/* stop when we catch up to the HC */

		// FIXME:  this assumes we won't get lapped when
		// latencies climb; that should be rare, but...
		// detect it, and just go all the way around.
		// FLR might help detect this case, so long as latencies
		// don't exceed periodic_size msec (default 1.024 sec).

		// FIXME:  likewise assumes HC doesn't halt mid-scan

		if (now_uframe == clock) {
			unsigned	now;

			if (!HC_IS_RUNNING (ehci_to_hcd(ehci)->state))
				break;
			ehci->next_uframe = now_uframe;
			now = readl (&ehci->regs->frame_index) % mod;
			if (now_uframe == now)
				break;

			/* rescan the rest of this frame, then ... */
			clock = now;
		} else {
			now_uframe++;
			now_uframe %= mod;
		}
	} 
}