ehci-sched.c

优龙2410linux2.6.8内核源代码

/*
 * Copyright (c) 2001-2003 by David Brownell
 * Copyright (c) 2003 Michal Sojka, for high-speed iso transfers
 * 
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/* this file is part of ehci-hcd.c */

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

/*
 * EHCI scheduled transaction support:  interrupt, iso, split iso
 * These are called "periodic" transactions in the EHCI spec.
 *
 * Note that for interrupt transfers, the QH/QTD manipulation is shared
 * with the "asynchronous" transaction support (control/bulk transfers).
 * The only real difference is in how interrupt transfers are scheduled.
 *
 * For ISO, we make an "iso_stream" head to serve the same role as a QH.
 * It keeps track of every ITD (or SITD) that's linked, and holds enough
 * pre-calculated schedule data to make appending to the queue be quick.
 */

static int ehci_get_frame (struct usb_hcd *hcd);

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

/*
 * periodic_next_shadow - return "next" pointer on shadow list
 * @periodic: host pointer to qh/itd/sitd
 * @tag: hardware tag for type of this record
 */
static union ehci_shadow *
periodic_next_shadow (union ehci_shadow *periodic, int tag)
{
	switch (tag) {
	case Q_TYPE_QH:
		return &periodic->qh->qh_next;
	case Q_TYPE_FSTN:
		return &periodic->fstn->fstn_next;
	case Q_TYPE_ITD:
		return &periodic->itd->itd_next;
	// case Q_TYPE_SITD:
	default:
		return &periodic->sitd->sitd_next;
	}
}

/* returns true after successful unlink */
/* caller must hold ehci->lock */
static int periodic_unlink (struct ehci_hcd *ehci, unsigned frame, void *ptr)
{
	union ehci_shadow	*prev_p = &ehci->pshadow [frame];
	u32			*hw_p = &ehci->periodic [frame];
	union ehci_shadow	here = *prev_p;
	union ehci_shadow	*next_p;

	/* find predecessor of "ptr"; hw and shadow lists are in sync */
	while (here.ptr && here.ptr != ptr) {
		prev_p = periodic_next_shadow (prev_p, Q_NEXT_TYPE (*hw_p));
		hw_p = &here.qh->hw_next;
		here = *prev_p;
	}
	/* an interrupt entry (at list end) could have been shared */
	if (!here.ptr) {
		dbg ("entry %p no longer on frame [%d]", ptr, frame);
		return 0;
	}
	// vdbg ("periodic unlink %p from frame %d", ptr, frame);

	/* update hardware list ... HC may still know the old structure, so
	 * don't change hw_next until it'll have purged its cache
	 */
	next_p = periodic_next_shadow (&here, Q_NEXT_TYPE (*hw_p));
	*hw_p = here.qh->hw_next;

	/* unlink from shadow list; HCD won't see old structure again */
	*prev_p = *next_p;
	next_p->ptr = NULL;

	return 1;
}

/* how many of the uframe's 125 usecs are allocated? */
static unsigned short
periodic_usecs (struct ehci_hcd *ehci, unsigned frame, unsigned uframe)
{
	u32			*hw_p = &ehci->periodic [frame];
	union ehci_shadow	*q = &ehci->pshadow [frame];
	unsigned		usecs = 0;

	while (q->ptr) {
		switch (Q_NEXT_TYPE (*hw_p)) {
		case Q_TYPE_QH:
			/* is it in the S-mask? */
			if (q->qh->hw_info2 & cpu_to_le32 (1 << uframe))
				usecs += q->qh->usecs;
			/* ... or C-mask? */
			if (q->qh->hw_info2 & cpu_to_le32 (1 << (8 + uframe)))
				usecs += q->qh->c_usecs;
			hw_p = &q->qh->hw_next;
			q = &q->qh->qh_next;
			break;
		case Q_TYPE_FSTN:
			/* for "save place" FSTNs, count the relevant INTR
			 * bandwidth from the previous frame
			 */
			if (q->fstn->hw_prev != EHCI_LIST_END) {
				ehci_dbg (ehci, "ignoring FSTN cost ...\n");
			}
			hw_p = &q->fstn->hw_next;
			q = &q->fstn->fstn_next;
			break;
		case Q_TYPE_ITD:
			usecs += q->itd->usecs [uframe];
			hw_p = &q->itd->hw_next;
			q = &q->itd->itd_next;
			break;
		case Q_TYPE_SITD:
			/* is it in the S-mask?  (count SPLIT, DATA) */
			if (q->sitd->hw_uframe & cpu_to_le32 (1 << uframe)) {
				if (q->sitd->hw_fullspeed_ep &
						__constant_cpu_to_le32 (1<<31))
					usecs += q->sitd->stream->usecs;
				else	/* worst case for OUT start-split */
					usecs += HS_USECS_ISO (188);
			}

			/* ... C-mask?  (count CSPLIT, DATA) */
			if (q->sitd->hw_uframe &
					cpu_to_le32 (1 << (8 + uframe))) {
				/* worst case for IN complete-split */
				usecs += q->sitd->stream->c_usecs;
			}

			hw_p = &q->sitd->hw_next;
			q = &q->sitd->sitd_next;
			break;
		default:
			BUG ();
		}
	}
#ifdef	DEBUG
	if (usecs > 100)
		err ("overallocated uframe %d, periodic is %d usecs",
			frame * 8 + uframe, usecs);
#endif
	return usecs;
}

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

static int same_tt (struct usb_device *dev1, struct usb_device *dev2)
{
	if (!dev1->tt || !dev2->tt)
		return 0;
	if (dev1->tt != dev2->tt)
		return 0;
	if (dev1->tt->multi)
		return dev1->ttport == dev2->ttport;
	else
		return 1;
}

/* return true iff the device's transaction translator is available
 * for a periodic transfer starting at the specified frame, using
 * all the uframes in the mask.
 */
static int tt_no_collision (
	struct ehci_hcd		*ehci,
	unsigned		period,
	struct usb_device	*dev,
	unsigned		frame,
	u32			uf_mask
)
{
	if (period == 0)	/* error */
		return 0;

	/* note bandwidth wastage:  split never follows csplit
	 * (different dev or endpoint) until the next uframe.
	 * calling convention doesn't make that distinction.
	 */
	for (; frame < ehci->periodic_size; frame += period) {
		union ehci_shadow	here;
		u32			type;

		here = ehci->pshadow [frame];
		type = Q_NEXT_TYPE (ehci->periodic [frame]);
		while (here.ptr) {
			switch (type) {
			case Q_TYPE_ITD:
				type = Q_NEXT_TYPE (here.itd->hw_next);
				here = here.itd->itd_next;
				continue;
			case Q_TYPE_QH:
				if (same_tt (dev, here.qh->dev)) {
					u32		mask;

					mask = le32_to_cpu (here.qh->hw_info2);
					/* "knows" no gap is needed */
					mask |= mask >> 8;
					if (mask & uf_mask)
						break;
				}
				type = Q_NEXT_TYPE (here.qh->hw_next);
				here = here.qh->qh_next;
				continue;
			case Q_TYPE_SITD:
				if (same_tt (dev, here.itd->urb->dev)) {
					u16		mask;

					mask = le32_to_cpu (here.sitd
								->hw_uframe);
					/* FIXME assumes no gap for IN! */
					mask |= mask >> 8;
					if (mask & uf_mask)
						break;
				}
				type = Q_NEXT_TYPE (here.qh->hw_next);
				here = here.sitd->sitd_next;
				continue;
			// case Q_TYPE_FSTN:
			default:
				ehci_dbg (ehci,
					"periodic frame %d bogus type %d\n",
					frame, type);
			}

			/* collision or error */
			return 0;
		}
	}

	/* no collision */
	return 1;
}

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

static int enable_periodic (struct ehci_hcd *ehci)
{
	u32	cmd;
	int	status;

	/* did clearing PSE did take effect yet?
	 * takes effect only at frame boundaries...
	 */
	status = handshake (&ehci->regs->status, STS_PSS, 0, 9 * 125);
	if (status != 0) {
		ehci->hcd.state = USB_STATE_HALT;
		return status;
	}

	cmd = readl (&ehci->regs->command) | CMD_PSE;
	writel (cmd, &ehci->regs->command);
	/* posted write ... PSS happens later */
	ehci->hcd.state = USB_STATE_RUNNING;

	/* make sure ehci_work scans these */
	ehci->next_uframe = readl (&ehci->regs->frame_index)
				% (ehci->periodic_size << 3);
	return 0;
}

static int disable_periodic (struct ehci_hcd *ehci)
{
	u32	cmd;
	int	status;

	/* did setting PSE not take effect yet?
	 * takes effect only at frame boundaries...
	 */
	status = handshake (&ehci->regs->status, STS_PSS, STS_PSS, 9 * 125);
	if (status != 0) {
		ehci->hcd.state = USB_STATE_HALT;
		return status;
	}

	cmd = readl (&ehci->regs->command) & ~CMD_PSE;
	writel (cmd, &ehci->regs->command);
	/* posted write ... */

	ehci->next_uframe = -1;
	return 0;
}

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

// FIXME microframe periods not yet handled

static void intr_deschedule (
	struct ehci_hcd	*ehci,
	struct ehci_qh	*qh,
	int		wait
) {
	int		status;
	unsigned	frame = qh->start;

	do {
		periodic_unlink (ehci, frame, qh);
		qh_put (qh);
		frame += qh->period;
	} while (frame < ehci->periodic_size);

	qh->qh_state = QH_STATE_UNLINK;
	qh->qh_next.ptr = NULL;
	ehci->periodic_sched--;

	/* maybe turn off periodic schedule */
	if (!ehci->periodic_sched)
		status = disable_periodic (ehci);
	else {
		status = 0;
		vdbg ("periodic schedule still enabled");
	}

	/*
	 * If the hc may be looking at this qh, then delay a uframe
	 * (yeech!) to be sure it's done.
	 * No other threads may be mucking with this qh.
	 */
	if (((ehci_get_frame (&ehci->hcd) - frame) % qh->period) == 0) {
		if (wait) {
			udelay (125);
			qh->hw_next = EHCI_LIST_END;
		} else {
			/* we may not be IDLE yet, but if the qh is empty
			 * the race is very short.  then if qh also isn't
			 * rescheduled soon, it won't matter.  otherwise...
			 */
			vdbg ("intr_deschedule...");
		}
	} else
		qh->hw_next = EHCI_LIST_END;

	qh->qh_state = QH_STATE_IDLE;

	/* update per-qh bandwidth utilization (for usbfs) */
	hcd_to_bus (&ehci->hcd)->bandwidth_allocated -= 
		(qh->usecs + qh->c_usecs) / qh->period;

	dbg ("descheduled qh %p, period = %d frame = %d count = %d, urbs = %d",
		qh, qh->period, frame,
		atomic_read (&qh->kref.refcount), ehci->periodic_sched);
}

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

	do {
		int	claimed;

// FIXME delete when intr_submit handles non-empty queues
// this gives us a one intr/frame limit (vs N/uframe)
// ... and also lets us avoid tracking split transactions
// that might collide at a given TT/hub.
		if (ehci->pshadow [frame].ptr)
			return 0;

		claimed = periodic_usecs (ehci, frame, uframe);
		if (claimed > usecs)
			return 0;

// FIXME update to handle sub-frame periods
	} 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,
	u32			*c_maskp
)
{
    	int		retval = -ENOSPC;

	if (!check_period (ehci, frame, uframe, qh->period, qh->usecs))
		goto done;
	if (!qh->c_usecs) {
		retval = 0;
		*c_maskp = cpu_to_le32 (0);
		goto done;
	}

	/* This is a split transaction; check the bandwidth available for
	 * the completion too.  Check both worst and best case gaps: worst
	 * case is SPLIT near uframe end, and CSPLIT near start ... best is
	 * vice versa.  Difference can be almost two uframe times, but we
	 * reserve unnecessary bandwidth (waste it) this way.  (Actually
	 * even better cases exist, like immediate device NAK.)
	 *
	 * FIXME don't even bother unless we know this TT is idle in that
	 * range of uframes ... for now, check_period() allows only one
	 * interrupt transfer per frame, so needn't check "TT busy" status
	 * when scheduling a split (QH, SITD, or FSTN).
	 *
	 * FIXME ehci 0.96 and above can use FSTNs
	 */
	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;

	*c_maskp = cpu_to_le32 (0x03 << (8 + uframe + qh->gap_uf));
	retval = 0;
done:
	return retval;
}

static int qh_schedule (struct ehci_hcd *ehci, struct ehci_qh *qh)
{
	int 		status;
	unsigned	uframe;
	u32		c_mask;
	unsigned	frame;		/* 0..(qh->period - 1), or NO_FRAME */

	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) & 0x00ff);
		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) {
		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--);
		if (status)
			goto done;
		qh->start = frame;

		/* reset S-frame and (maybe) C-frame masks */
		qh->hw_info2 &= ~__constant_cpu_to_le32(0xffff);