ehci-q.c

usb host driver for linux

/*
 * Copyright (c) 2001-2002 by David Brownell
 * 
 * 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 hardware queue manipulation ... the core.  QH/QTD manipulation.
 *
 * Control, bulk, and interrupt traffic all use "qh" lists.  They list "qtd"
 * entries describing USB transactions, max 16-20kB/entry (with 4kB-aligned
 * buffers needed for the larger number).  We use one QH per endpoint, queue
 * multiple urbs (all three types) per endpoint.  URBs may need several qtds.
 *
 * ISO traffic uses "ISO TD" (itd, and sitd) records, and (along with
 * interrupts) needs careful scheduling.  Performance improvements can be
 * an ongoing challenge.  That's in "ehci-sched.c".
 * 
 * USB 1.1 devices are handled (a) by "companion" OHCI or UHCI root hubs,
 * or otherwise through transaction translators (TTs) in USB 2.0 hubs using
 * (b) special fields in qh entries or (c) split iso entries.  TTs will
 * buffer low/full speed data so the host collects it at high speed.
 */

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

/* fill a qtd, returning how much of the buffer we were able to queue up */

static int
qtd_fill (struct ehci_qtd *qtd, dma_addr_t buf, size_t len,
		int token, int maxpacket)
{
	int	i, count;
	u64	addr = buf;

	/* one buffer entry per 4K ... first might be short or unaligned */
	qtd->hw_buf [0] = cpu_to_le32 ((u32)addr);
	qtd->hw_buf_hi [0] = cpu_to_le32 ((u32)(addr >> 32));
	count = 0x1000 - (buf & 0x0fff);	/* rest of that page */
	if (likely (len < count))		/* ... iff needed */
		count = len;
	else {
		buf +=  0x1000;
		buf &= ~0x0fff;

		/* per-qtd limit: from 16K to 20K (best alignment) */
		for (i = 1; count < len && i < 5; i++) {
			addr = buf;
			qtd->hw_buf [i] = cpu_to_le32 ((u32)addr);
			qtd->hw_buf_hi [i] = cpu_to_le32 ((u32)(addr >> 32));
			buf += 0x1000;
			if ((count + 0x1000) < len)
				count += 0x1000;
			else
				count = len;
		}

		/* short packets may only terminate transfers */
		if (count != len)
			count -= (count % maxpacket);
	}
	qtd->hw_token = cpu_to_le32 ((count << 16) | token);
	qtd->length = count;

	return count;
}

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

static inline void
qh_update (struct ehci_hcd *ehci, struct ehci_qh *qh, struct ehci_qtd *qtd)
{
	/* writes to an active overlay are unsafe */
	BUG_ON(qh->qh_state != QH_STATE_IDLE);

	qh->hw_qtd_next = QTD_NEXT (qtd->qtd_dma);
	qh->hw_alt_next = EHCI_LIST_END;

	/* Except for control endpoints, we make hardware maintain data
	 * toggle (like OHCI) ... here (re)initialize the toggle in the QH,
	 * and set the pseudo-toggle in udev. Only usb_clear_halt() will
	 * ever clear it.
	 */
	if (!(qh->hw_info1 & cpu_to_le32(1 << 14))) {
		unsigned	is_out, epnum;

		is_out = !(qtd->hw_token & cpu_to_le32(1 << 8));
		epnum = (le32_to_cpup(&qh->hw_info1) >> 8) & 0x0f;
		if (unlikely (!usb_gettoggle (qh->dev, epnum, is_out))) {
			qh->hw_token &= ~__constant_cpu_to_le32 (QTD_TOGGLE);
			usb_settoggle (qh->dev, epnum, is_out, 1);
		}
	}

	/* HC must see latest qtd and qh data before we clear ACTIVE+HALT */
	wmb ();
	qh->hw_token &= __constant_cpu_to_le32 (QTD_TOGGLE | QTD_STS_PING);
}

/* if it weren't for a common silicon quirk (writing the dummy into the qh
 * overlay, so qh->hw_token wrongly becomes inactive/halted), only fault
 * recovery (including urb dequeue) would need software changes to a QH...
 */
static void
qh_refresh (struct ehci_hcd *ehci, struct ehci_qh *qh)
{
	struct ehci_qtd *qtd;

	if (list_empty (&qh->qtd_list))
		qtd = qh->dummy;
	else {
		qtd = list_entry (qh->qtd_list.next,
				struct ehci_qtd, qtd_list);
		/* first qtd may already be partially processed */
		if (cpu_to_le32 (qtd->qtd_dma) == qh->hw_current)
			qtd = NULL;
	}

	if (qtd)
		qh_update (ehci, qh, qtd);
}

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

static void qtd_copy_status (
	struct ehci_hcd *ehci,
	struct urb *urb,
	size_t length,
	u32 token
)
{
	/* count IN/OUT bytes, not SETUP (even short packets) */
	if (likely (QTD_PID (token) != 2))
		urb->actual_length += length - QTD_LENGTH (token);

	/* don't modify error codes */
	if (unlikely (urb->status != -EINPROGRESS))
		return;

	/* force cleanup after short read; not always an error */
	if (unlikely (IS_SHORT_READ (token)))
		urb->status = -EREMOTEIO;

	/* serious "can't proceed" faults reported by the hardware */
	if (token & QTD_STS_HALT) {
		if (token & QTD_STS_BABBLE) {
			/* FIXME "must" disable babbling device's port too */
			urb->status = -EOVERFLOW;
		} else if (token & QTD_STS_MMF) {
			/* fs/ls interrupt xfer missed the complete-split */
			urb->status = -EPROTO;
		} else if (token & QTD_STS_DBE) {
			urb->status = (QTD_PID (token) == 1) /* IN ? */
				? -ENOSR  /* hc couldn't read data */
				: -ECOMM; /* hc couldn't write data */
		} else if (token & QTD_STS_XACT) {
			/* timeout, bad crc, wrong PID, etc; retried */
			if (QTD_CERR (token))
				urb->status = -EPIPE;
			else {
				ehci_dbg (ehci, "devpath %s ep%d%s 3strikes\n",
					urb->dev->devpath,
					usb_pipeendpoint (urb->pipe),
					usb_pipein (urb->pipe) ? "in" : "out");
				urb->status = -EPROTO;
			}
		/* CERR nonzero + no errors + halt --> stall */
		} else if (QTD_CERR (token))
			urb->status = -EPIPE;
		else	/* unknown */
			urb->status = -EPROTO;

		ehci_vdbg (ehci,
			"dev%d ep%d%s qtd token %08x --> status %d\n",
			usb_pipedevice (urb->pipe),
			usb_pipeendpoint (urb->pipe),
			usb_pipein (urb->pipe) ? "in" : "out",
			token, urb->status);

		/* if async CSPLIT failed, try cleaning out the TT buffer */
		if (urb->status != -EPIPE
				&& urb->dev->tt && !usb_pipeint (urb->pipe)
				&& ((token & QTD_STS_MMF) != 0
					|| QTD_CERR(token) == 0)
				&& (!ehci_is_TDI(ehci)
                	                || urb->dev->tt->hub !=
					   ehci_to_hcd(ehci)->self.root_hub)) {
#ifdef DEBUG
			struct usb_device *tt = urb->dev->tt->hub;
			dev_dbg (&tt->dev,
				"clear tt buffer port %d, a%d ep%d t%08x\n",
				urb->dev->ttport, urb->dev->devnum,
				usb_pipeendpoint (urb->pipe), token);
#endif /* DEBUG */
			usb_hub_tt_clear_buffer (urb->dev, urb->pipe);
		}
	}
}

static void
ehci_urb_done (struct ehci_hcd *ehci, struct urb *urb, struct pt_regs *regs)
__releases(ehci->lock)
__acquires(ehci->lock)
{
	if (likely (urb->hcpriv != NULL)) {
		struct ehci_qh	*qh = (struct ehci_qh *) urb->hcpriv;

		/* S-mask in a QH means it's an interrupt urb */
		if ((qh->hw_info2 & __constant_cpu_to_le32 (0x00ff)) != 0) {

			/* ... update hc-wide periodic stats (for usbfs) */
			ehci_to_hcd(ehci)->self.bandwidth_int_reqs--;
		}
		qh_put (qh);
	}

	spin_lock (&urb->lock);
	urb->hcpriv = NULL;
	switch (urb->status) {
	case -EINPROGRESS:		/* success */
		urb->status = 0;
	default:			/* fault */
		COUNT (ehci->stats.complete);
		break;
	case -EREMOTEIO:		/* fault or normal */
		if (!(urb->transfer_flags & URB_SHORT_NOT_OK))
			urb->status = 0;
		COUNT (ehci->stats.complete);
		break;
	case -ECONNRESET:		/* canceled */
	case -ENOENT:
		COUNT (ehci->stats.unlink);
		break;
	}
	spin_unlock (&urb->lock);

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

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

static void start_unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh);
static void unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh);

static void intr_deschedule (struct ehci_hcd *ehci, struct ehci_qh *qh);
static int qh_schedule (struct ehci_hcd *ehci, struct ehci_qh *qh);

/*
 * Process and free completed qtds for a qh, returning URBs to drivers.
 * Chases up to qh->hw_current.  Returns number of completions called,
 * indicating how much "real" work we did.
 */
#define HALT_BIT __constant_cpu_to_le32(QTD_STS_HALT)
static unsigned
qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh, struct pt_regs *regs)
{
	struct ehci_qtd		*last = NULL, *end = qh->dummy;
	struct list_head	*entry, *tmp;
	int			stopped;
	unsigned		count = 0;
	int			do_status = 0;
	u8			state;

	if (unlikely (list_empty (&qh->qtd_list)))
		return count;

	/* completions (or tasks on other cpus) must never clobber HALT
	 * till we've gone through and cleaned everything up, even when
	 * they add urbs to this qh's queue or mark them for unlinking.
	 *
	 * NOTE:  unlinking expects to be done in queue order.
	 */
	state = qh->qh_state;
	qh->qh_state = QH_STATE_COMPLETING;
	stopped = (state == QH_STATE_IDLE);

	/* remove de-activated QTDs from front of queue.
	 * after faults (including short reads), cleanup this urb
	 * then let the queue advance.
	 * if queue is stopped, handles unlinks.
	 */
	list_for_each_safe (entry, tmp, &qh->qtd_list) {
		struct ehci_qtd	*qtd;
		struct urb	*urb;
		u32		token = 0;

		qtd = list_entry (entry, struct ehci_qtd, qtd_list);
		urb = qtd->urb;

		/* clean up any state from previous QTD ...*/
		if (last) {
			if (likely (last->urb != urb)) {
				ehci_urb_done (ehci, last->urb, regs);
				count++;
			}
			ehci_qtd_free (ehci, last);
			last = NULL;
		}

		/* ignore urbs submitted during completions we reported */
		if (qtd == end)
			break;

		/* hardware copies qtd out of qh overlay */
		rmb ();
		token = le32_to_cpu (qtd->hw_token);

		/* always clean up qtds the hc de-activated */
		if ((token & QTD_STS_ACTIVE) == 0) {

			if ((token & QTD_STS_HALT) != 0) {
				stopped = 1;

			/* magic dummy for some short reads; qh won't advance.
			 * that silicon quirk can kick in with this dummy too.
			 */
			} else if (IS_SHORT_READ (token)
					&& !(qtd->hw_alt_next & EHCI_LIST_END)) {
				stopped = 1;
				goto halt;
			}

		/* stop scanning when we reach qtds the hc is using */
		} else if (likely (!stopped
				&& HC_IS_RUNNING (ehci_to_hcd(ehci)->state))) {
			break;

		} else {
			stopped = 1;

			if (unlikely (!HC_IS_RUNNING (ehci_to_hcd(ehci)->state)))
				urb->status = -ESHUTDOWN;

			/* ignore active urbs unless some previous qtd
			 * for the urb faulted (including short read) or
			 * its urb was canceled.  we may patch qh or qtds.
			 */
			if (likely (urb->status == -EINPROGRESS))
				continue;
			
			/* issue status after short control reads */
			if (unlikely (do_status != 0)
					&& QTD_PID (token) == 0 /* OUT */) {
				do_status = 0;
				continue;
			}

			/* token in overlay may be most current */
			if (state == QH_STATE_IDLE
					&& cpu_to_le32 (qtd->qtd_dma)
						== qh->hw_current)
				token = le32_to_cpu (qh->hw_token);

			/* force halt for unlinked or blocked qh, so we'll
			 * patch the qh later and so that completions can't
			 * activate it while we "know" it's stopped.
			 */
			if ((HALT_BIT & qh->hw_token) == 0) {
halt:
				qh->hw_token |= HALT_BIT;
				wmb ();
			}
		}
 
		/* remove it from the queue */
		spin_lock (&urb->lock);
		qtd_copy_status (ehci, urb, qtd->length, token);
		do_status = (urb->status == -EREMOTEIO)
				&& usb_pipecontrol (urb->pipe);
		spin_unlock (&urb->lock);

		if (stopped && qtd->qtd_list.prev != &qh->qtd_list) {
			last = list_entry (qtd->qtd_list.prev,
					struct ehci_qtd, qtd_list);
			last->hw_next = qtd->hw_next;
		}
		list_del (&qtd->qtd_list);
		last = qtd;
	}

	/* last urb's completion might still need calling */
	if (likely (last != NULL)) {
		ehci_urb_done (ehci, last->urb, regs);
		count++;
		ehci_qtd_free (ehci, last);
	}

	/* restore original state; caller must unlink or relink */
	qh->qh_state = state;

	/* be sure the hardware's done with the qh before refreshing
	 * it after fault cleanup, or recovering from silicon wrongly
	 * overlaying the dummy qtd (which reduces DMA chatter).
	 */
	if (stopped != 0 || qh->hw_qtd_next == EHCI_LIST_END) {
		switch (state) {
		case QH_STATE_IDLE:
			qh_refresh(ehci, qh);
			break;
		case QH_STATE_LINKED:
			/* should be rare for periodic transfers,
			 * except maybe high bandwidth ...
			 */
			if (qh->period) {
				intr_deschedule (ehci, qh);
				(void) qh_schedule (ehci, qh);
			} else
				unlink_async (ehci, qh);
			break;
		/* otherwise, unlink already started */
		}
	}

	return count;
}

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

// high bandwidth multiplier, as encoded in highspeed endpoint descriptors
#define hb_mult(wMaxPacketSize) (1 + (((wMaxPacketSize) >> 11) & 0x03))
// ... and packet size, for any kind of endpoint descriptor
#define max_packet(wMaxPacketSize) ((wMaxPacketSize) & 0x07ff)

/*
 * reverse of qh_urb_transaction:  free a list of TDs.
 * used for cleanup after errors, before HC sees an URB's TDs.
 */
static void qtd_list_free (
	struct ehci_hcd		*ehci,
	struct urb		*urb,
	struct list_head	*qtd_list
) {
	struct list_head	*entry, *temp;

	list_for_each_safe (entry, temp, qtd_list) {
		struct ehci_qtd	*qtd;

		qtd = list_entry (entry, struct ehci_qtd, qtd_list);
		list_del (&qtd->qtd_list);
		ehci_qtd_free (ehci, qtd);
	}
}

/*
 * create a list of filled qtds for this URB; won't link into qh.
 */
static struct list_head *
qh_urb_transaction (
	struct ehci_hcd		*ehci,
	struct urb		*urb,
	struct list_head	*head,
	int			flags
) {
	struct ehci_qtd		*qtd, *qtd_prev;
	dma_addr_t		buf;
	int			len, maxpacket;
	int			is_input;
	u32			token;

	/*
	 * URBs map to sequences of QTDs:  one logical transaction
	 */
	qtd = ehci_qtd_alloc (ehci, flags);
	if (unlikely (!qtd))
		return NULL;
	list_add_tail (&qtd->qtd_list, head);
	qtd->urb = urb;

	token = QTD_STS_ACTIVE;
	token |= (EHCI_TUNE_CERR << 10);
	/* for split transactions, SplitXState initialized to zero */

	len = urb->transfer_buffer_length;
	is_input = usb_pipein (urb->pipe);
	if (usb_pipecontrol (urb->pipe)) {
		/* SETUP pid */
		qtd_fill (qtd, urb->setup_dma, sizeof (struct usb_ctrlrequest),
			token | (2 /* "setup" */ << 8), 8);

		/* ... and always at least one more pid */
		token ^= QTD_TOGGLE;
		qtd_prev = qtd;
		qtd = ehci_qtd_alloc (ehci, flags);
		if (unlikely (!qtd))
			goto cleanup;
		qtd->urb = urb;
		qtd_prev->hw_next = QTD_NEXT (qtd->qtd_dma);
		list_add_tail (&qtd->qtd_list, head);
	} 

	/*
	 * data transfer stage:  buffer setup
	 */
	if (likely (len > 0))
		buf = urb->transfer_dma;
	else
		buf = 0;

	/* for zero length DATA stages, STATUS is always IN */
	if (!buf || is_input)
		token |= (1 /* "in" */ << 8);
	/* else it's already initted to "out" pid (0 << 8) */

	maxpacket = max_packet(usb_maxpacket(urb->dev, urb->pipe, !is_input));

	/*
	 * buffer gets wrapped in one or more qtds;
	 * last one may be "short" (including zero len)
	 * and may serve as a control status ack
	 */
	for (;;) {
		int this_qtd_len;

		this_qtd_len = qtd_fill (qtd, buf, len, token, maxpacket);
		len -= this_qtd_len;
		buf += this_qtd_len;
		if (is_input)
			qtd->hw_alt_next = ehci->async->hw_alt_next;