ehci-sched.c

ep9315平台下USB驱动的源码

	for (i = 0; i < 2; i++) {
		itd->hw_bufp [i] = cpu_to_le32 ((u32) temp);
		itd->hw_bufp_hi [i] = cpu_to_le32 ((u32)(temp >> 32));
		temp += 0x1000;
	}
	itd->buf_dma = dma;

	/*
	 * this might be a "high bandwidth" highspeed endpoint,
	 * as encoded in the ep descriptor's maxpacket field
	 */
	epnum = usb_pipeendpoint (urb->pipe);
	is_input = usb_pipein (urb->pipe);
	if (is_input) {
		maxp = urb->dev->epmaxpacketin [epnum];
		buf1 = (1 << 11);
	} else {
		maxp = urb->dev->epmaxpacketout [epnum];
		buf1 = 0;
	}
	buf1 |= (maxp & 0x03ff);
	multi = 1;
	multi += (maxp >> 11) & 0x03;
	maxp &= 0x03ff;
	maxp *= multi;

	/* transfer can't fit in any uframe? */ 
	if (length < 0 || maxp < length) {
		dbg ("BAD iso packet: %d bytes, max %d, urb %p [%d] (of %d)",
			length, maxp, urb, index,
			urb->iso_frame_desc [index].length);
		return -ENOSPC;
	}
	itd->usecs = usb_calc_bus_time (USB_SPEED_HIGH, is_input, 1, length);

	/* "plus" info in low order bits of buffer pointers */
	itd->hw_bufp [0] |= cpu_to_le32 ((epnum << 8) | urb->dev->devnum);
	itd->hw_bufp [1] |= cpu_to_le32 (buf1);
	itd->hw_bufp [2] |= cpu_to_le32 (multi);

	/* figure hw_transaction[] value (it's scheduled later) */
	itd->transaction = EHCI_ISOC_ACTIVE;
	itd->transaction |= dma & 0x0fff;		/* offset; buffer=0 */
	if ((index + 1) == urb->number_of_packets)
		itd->transaction |= EHCI_ITD_IOC; 	/* end-of-urb irq */
	itd->transaction |= length << 16;
	cpu_to_le32s (&itd->transaction);

	return 0;
}

static int
itd_urb_transaction (
	struct ehci_hcd		*ehci,
	struct urb		*urb,
	int			mem_flags
) {
	int			frame_index;
	struct ehci_itd		*first_itd, *itd;
	int			status;
	dma_addr_t		itd_dma;

	/* allocate/init ITDs */
	for (frame_index = 0, first_itd = 0;
			frame_index < urb->number_of_packets;
			frame_index++) {
		itd = pci_pool_alloc (ehci->itd_pool, mem_flags, &itd_dma);
		if (!itd) {
			status = -ENOMEM;
			goto fail;
		}
		memset (itd, 0, sizeof *itd);
		itd->itd_dma = itd_dma;

		status = itd_fill (ehci, itd, urb, frame_index,
				urb->transfer_dma);
		if (status != 0)
			goto fail;

		if (first_itd)
			list_add_tail (&itd->itd_list,
					&first_itd->itd_list);
		else {
			INIT_LIST_HEAD (&itd->itd_list);
			urb->hcpriv = first_itd = itd;
		}
	}
	urb->error_count = 0;
	return 0;

fail:
	if (urb->hcpriv)
		itd_free_list (ehci, urb);
	return status;
}

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

static inline void
itd_link (struct ehci_hcd *ehci, unsigned frame, struct ehci_itd *itd)
{
	/* always prepend ITD/SITD ... only QH tree is order-sensitive */
	itd->itd_next = ehci->pshadow [frame];
	itd->hw_next = ehci->periodic [frame];
	ehci->pshadow [frame].itd = itd;
	ehci->periodic [frame] = cpu_to_le32 (itd->itd_dma) | Q_TYPE_ITD;
}

/*
 * return zero on success, else -errno
 * - start holds first uframe to start scheduling into
 * - max is the first uframe it's NOT (!) OK to start scheduling into
 * math to be done modulo "mod" (ehci->periodic_size << 3)
 */
static int get_iso_range (
	struct ehci_hcd		*ehci,
	struct urb		*urb,
	unsigned		*start,
	unsigned		*max,
	unsigned		mod
) {
	struct list_head	*lh;
	struct hcd_dev		*dev = urb->dev->hcpriv;
	int			last = -1;
	unsigned		now, span, end;

	span = urb->interval * urb->number_of_packets;

	/* first see if we know when the next transfer SHOULD happen */
	list_for_each (lh, &dev->urb_list) {
		struct urb	*u;
		struct ehci_itd	*itd;
		unsigned	s;

		u = list_entry (lh, struct urb, urb_list);
		if (u == urb || u->pipe != urb->pipe)
			continue;
		if (u->interval != urb->interval) {	/* must not change! */ 
			dbg ("urb %p interval %d ... != %p interval %d",
				u, u->interval, urb, urb->interval);
			return -EINVAL;
		}
		
		/* URB for this endpoint... covers through when?  */
		itd = urb->hcpriv;
		s = itd->uframe + u->interval * u->number_of_packets;
		if (last < 0)
			last = s;
		else {
			/*
			 * So far we can only queue two ISO URBs...
			 *
			 * FIXME do interval math, figure out whether
			 * this URB is "before" or not ... also, handle
			 * the case where the URB might have completed,
			 * but hasn't yet been processed.
			 */
			dbg ("NYET: queue >2 URBs per ISO endpoint");
			return -EDOM;
		}
	}

	/* calculate the legal range [start,max) */
	now = readl (&ehci->regs->frame_index) + 1;	/* next uframe */
	if (!ehci->periodic_sched)
		now += 8;				/* startup delay */
	now %= mod;
	end = now + mod;
	if (last < 0) {
		*start = now + ehci->i_thresh + /* paranoia */ 1;
		*max = end - span;
		if (*max < *start + 1)
			*max = *start + 1;
	} else {
		*start = last % mod;
		*max = (last + 1) % mod;
	}

	/* explicit start frame? */
	if (!(urb->transfer_flags & URB_ISO_ASAP)) {
		unsigned	temp;

		/* sanity check: must be in range */
		urb->start_frame %= ehci->periodic_size;
		temp = urb->start_frame << 3;
		if (temp < *start)
			temp += mod;
		if (temp > *max)
			return -EDOM;

		/* use that explicit start frame */
		*start = urb->start_frame << 3;
		temp += 8;
		if (temp < *max)
			*max = temp;
	}

	// FIXME minimize wraparound to "now" ... insist max+span
	// (and start+span) remains a few frames short of "end"

	*max %= ehci->periodic_size;
	if ((*start + span) < end)
		return 0;
	return -EFBIG;
}

static int
itd_schedule (struct ehci_hcd *ehci, struct urb *urb)
{
	unsigned	start, max, i;
	int		status;
	unsigned	mod = ehci->periodic_size << 3;

	for (i = 0; i < urb->number_of_packets; i++) {
		urb->iso_frame_desc [i].status = -EINPROGRESS;
		urb->iso_frame_desc [i].actual_length = 0;
	}

	if ((status = get_iso_range (ehci, urb, &start, &max, mod)) != 0)
		return status;

	do {
		unsigned	uframe;
		unsigned	usecs;
		struct ehci_itd	*itd;

		/* check schedule: enough space? */
		itd = urb->hcpriv;
		uframe = start;
		for (i = 0, uframe = start;
				i < urb->number_of_packets;
				i++, uframe += urb->interval) {
			uframe %= mod;

			/* can't commit more than 80% periodic == 100 usec */
			if (periodic_usecs (ehci, uframe >> 3, uframe & 0x7)
					> (100 - itd->usecs)) {
				itd = 0;
				break;
			}
			itd = list_entry (itd->itd_list.next,
				struct ehci_itd, itd_list);
		}
		if (!itd)
			continue;
		
		/* that's where we'll schedule this! */
		itd = urb->hcpriv;
		urb->start_frame = start >> 3;
		vdbg ("ISO urb %p (%d packets period %d) starting %d.%d",
			urb, urb->number_of_packets, urb->interval,
			urb->start_frame, start & 0x7);
		for (i = 0, uframe = start, usecs = 0;
				i < urb->number_of_packets;
				i++, uframe += urb->interval) {
			uframe %= mod;

			itd->uframe = uframe;
			itd->hw_transaction [uframe & 0x07] = itd->transaction;
			itd_link (ehci, (uframe >> 3) % ehci->periodic_size,
				itd);
			wmb ();
			usecs += itd->usecs;

			itd = list_entry (itd->itd_list.next,
				struct ehci_itd, itd_list);
		}

		/* update bandwidth utilization records (for usbfs)
		 *
		 * FIXME This claims each URB queued to an endpoint, as if
		 * transfers were concurrent, not sequential.  So bandwidth
		 * typically gets double-billed ... comes from tying it to
		 * URBs rather than endpoints in the schedule.  Luckily we
		 * don't use this usbfs data for serious decision making.
		 */
		usecs /= urb->number_of_packets;
		usecs /= urb->interval;
		usecs >>= 3;
		if (usecs < 1)
			usecs = 1;
		usb_claim_bandwidth (urb->dev, urb, usecs, 1);

		/* maybe enable periodic schedule processing */
		if (!ehci->periodic_sched++) {
			if ((status =  enable_periodic (ehci)) != 0) {
				// FIXME deschedule right away
				err ("itd_schedule, enable = %d", status);
			}
		}

		return 0;

	} while ((start = ++start % mod) != max);

	/* no room in the schedule */
	dbg ("urb %p, CAN'T SCHEDULE", urb);
	return -ENOSPC;
}

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

#define	ISO_ERRS (EHCI_ISOC_BUF_ERR | EHCI_ISOC_BABBLE | EHCI_ISOC_XACTERR)

static unsigned
itd_complete (
	struct ehci_hcd	*ehci,
	struct ehci_itd	*itd,
	unsigned	uframe,
	struct pt_regs	*regs
) {
	struct urb				*urb = itd->urb;
	struct usb_iso_packet_descriptor	*desc;
	u32					t;

	/* update status for this uframe's transfers */
	desc = &urb->iso_frame_desc [itd->index];

	t = itd->hw_transaction [uframe];
	itd->hw_transaction [uframe] = 0;
	if (t & EHCI_ISOC_ACTIVE)
		desc->status = -EXDEV;
	else if (t & ISO_ERRS) {
		urb->error_count++;
		if (t & EHCI_ISOC_BUF_ERR)
			desc->status = usb_pipein (urb->pipe)
				? -ENOSR  /* couldn't read */
				: -ECOMM; /* couldn't write */
		else if (t & EHCI_ISOC_BABBLE)
			desc->status = -EOVERFLOW;
		else /* (t & EHCI_ISOC_XACTERR) */
			desc->status = -EPROTO;

		/* HC need not update length with this error */
		if (!(t & EHCI_ISOC_BABBLE))
			desc->actual_length += EHCI_ITD_LENGTH (t);
	} else {
		desc->status = 0;
		desc->actual_length += EHCI_ITD_LENGTH (t);
	}

	vdbg ("itd %p urb %p packet %d/%d trans %x status %d len %d",
		itd, urb, itd->index + 1, urb->number_of_packets,
		t, desc->status, desc->actual_length);

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

	/*
	 * Always give the urb back to the driver ... expect it to submit
	 * a new urb (or resubmit this), and to have another already queued
	 * when un-interrupted transfers are needed.
	 *
	 * NOTE that for now we don't accelerate ISO unlinks; they just
	 * happen according to the current schedule.  Means a delay of
	 * up to about a second (max).
	 */
	itd_free_list (ehci, urb);
	if (urb->status == -EINPROGRESS)
		urb->status = 0;

	/* complete() can reenter this HCD */
	spin_unlock (&ehci->lock);
	usb_hcd_giveback_urb (&ehci->hcd, urb, regs);
	spin_lock (&ehci->lock);

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

	return 1;
}

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

static int itd_submit (struct ehci_hcd *ehci, struct urb *urb, int mem_flags)
{
	int		status;
	unsigned long	flags;

	dbg ("itd_submit urb %p", urb);

	/* allocate ITDs w/o locking anything */
	status = itd_urb_transaction (ehci, urb, mem_flags);
	if (status < 0)
		return status;

	/* schedule ... need to lock */
	spin_lock_irqsave (&ehci->lock, flags);
	status = itd_schedule (ehci, urb);
	spin_unlock_irqrestore (&ehci->lock, flags);
	if (status < 0)
		itd_free_list (ehci, urb);

	return status;
}

#ifdef have_split_iso

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

/*
 * "Split ISO TDs" ... used for USB 1.1 devices going through
 * the TTs in USB 2.0 hubs.
 *
 * FIXME not yet implemented
 */

#endif /* have_split_iso */

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

static void
scan_periodic (struct ehci_hcd *ehci, struct pt_regs *regs)
{
	unsigned	frame, clock, now_uframe, mod;
	unsigned	count = 0;

	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.
	 * Don't scan ISO entries more than once, though.
	 */
	frame = ehci->next_uframe >> 3;
	if (HCD_IS_RUNNING (ehci->hcd.state))
		now_uframe = readl (&ehci->regs->frame_index);
	else
		now_uframe = (frame << 3) - 1;
	now_uframe %= mod;
	clock = now_uframe >> 3;

	for (;;) {
		union ehci_shadow	q, *q_p;
		u32			type, *hw_p;
		unsigned		uframes;

restart:
		/* scan schedule to _before_ current frame index */
		if (frame == clock)
			uframes = now_uframe & 0x07;
		else
			uframes = 8;

		q_p = &ehci->pshadow [frame];
		hw_p = &ehci->periodic [frame];
		q.ptr = q_p->ptr;
		type = Q_NEXT_TYPE (*hw_p);

		/* scan each element in frame's queue for completions */
		while (q.ptr != 0) {
			int			last;
			unsigned		uf;
			union ehci_shadow	temp;

			switch (type) {
			case Q_TYPE_QH:
				last = (q.qh->hw_next == EHCI_LIST_END);
				temp = q.qh->qh_next;
				type = Q_NEXT_TYPE (q.qh->hw_next);
				count += intr_complete (ehci, frame,
						qh_get (q.qh), regs);
				qh_put (ehci, q.qh);
				q = temp;
				break;
			case Q_TYPE_FSTN:
				last = (q.fstn->hw_next == EHCI_LIST_END);
				/* 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:
				last = (q.itd->hw_next == EHCI_LIST_END);

				/* Unlink each (S)ITD we see, since the ISO
				 * URB model forces constant rescheduling.
				 * That complicates sharing uframes in ITDs,
				 * and means we need to skip uframes the HC
				 * hasn't yet processed.
				 */
				for (uf = 0; uf < uframes; uf++) {
					if (q.itd->hw_transaction [uf] != 0) {
						temp = q;
						*q_p = q.itd->itd_next;
						*hw_p = q.itd->hw_next;
						type = Q_NEXT_TYPE (*hw_p);

						/* might free q.itd ... */
						count += itd_complete (ehci,
							temp.itd, uf, regs);
						break;
					}
				}
				/* we might skip this ITD's uframe ... */
				if (uf == uframes) {
					q_p = &q.itd->itd_next;
					hw_p = &q.itd->hw_next;
					type = Q_NEXT_TYPE (q.itd->hw_next);
				}

				q = *q_p;
				break;
#ifdef have_split_iso
			case Q_TYPE_SITD:
				last = (q.sitd->hw_next == EHCI_LIST_END);
				sitd_complete (ehci, q.sitd);
				type = Q_NEXT_TYPE (q.sitd->hw_next);

				// FIXME unlink SITD after split completes
				q = q.sitd->sitd_next;
				break;
#endif /* have_split_iso */
			default:
				dbg ("corrupt type %d frame %d shadow %p",
					type, frame, q.ptr);
				// BUG ();
				last = 1;
				q.ptr = 0;
			}

			/* did completion remove an interior q entry? */
			if (unlikely (q.ptr == 0 && !last))
				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 (frame == clock) {
			unsigned	now;

			if (!HCD_IS_RUNNING (ehci->hcd.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 ... */
			now_uframe = now;
			clock = now_uframe >> 3;
		} else
			frame = (frame + 1) % ehci->periodic_size;
	} 
}