drivers/usb/host/ehci-timer.c - third_party/kernel - Git at Google

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Copyright (C) 2012 by Alan Stern
  */

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

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

 /* Set a bit in the USBCMD register */
 static void ehci_set_command_bit(struct ehci_hcd *ehci, u32 bit)
 {
 	ehci->command |= bit;
 	ehci_writel(ehci, ehci->command, &ehci->regs->command);

 	/* unblock posted write */
 	ehci_readl(ehci, &ehci->regs->command);
 }

 /* Clear a bit in the USBCMD register */
 static void ehci_clear_command_bit(struct ehci_hcd *ehci, u32 bit)
 {
 	ehci->command &= ~bit;
 	ehci_writel(ehci, ehci->command, &ehci->regs->command);

 	/* unblock posted write */
 	ehci_readl(ehci, &ehci->regs->command);
 }

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

 /*
  * EHCI timer support...  Now using hrtimers.
  *
  * Lots of different events are triggered from ehci->hrtimer.  Whenever
  * the timer routine runs, it checks each possible event; events that are
  * currently enabled and whose expiration time has passed get handled.
  * The set of enabled events is stored as a collection of bitflags in
  * ehci->enabled_hrtimer_events, and they are numbered in order of
  * increasing delay values (ranging between 1 ms and 100 ms).
  *
  * Rather than implementing a sorted list or tree of all pending events,
  * we keep track only of the lowest-numbered pending event, in
  * ehci->next_hrtimer_event.  Whenever ehci->hrtimer gets restarted, its
  * expiration time is set to the timeout value for this event.
  *
  * As a result, events might not get handled right away; the actual delay
  * could be anywhere up to twice the requested delay.  This doesn't
  * matter, because none of the events are especially time-critical.  The
  * ones that matter most all have a delay of 1 ms, so they will be
  * handled after 2 ms at most, which is okay.  In addition to this, we
  * allow for an expiration range of 1 ms.
  */

 /*
  * Delay lengths for the hrtimer event types.
  * Keep this list sorted by delay length, in the same order as
  * the event types indexed by enum ehci_hrtimer_event in ehci.h.
  */
 static unsigned event_delays_ns[] = {
 	1 * NSEC_PER_MSEC,	/* EHCI_HRTIMER_POLL_ASS */
 	1 * NSEC_PER_MSEC,	/* EHCI_HRTIMER_POLL_PSS */
 	1 * NSEC_PER_MSEC,	/* EHCI_HRTIMER_POLL_DEAD */
 	1125 * NSEC_PER_USEC,	/* EHCI_HRTIMER_UNLINK_INTR */
 	2 * NSEC_PER_MSEC,	/* EHCI_HRTIMER_FREE_ITDS */
 	2 * NSEC_PER_MSEC,	/* EHCI_HRTIMER_ACTIVE_UNLINK */
 	5 * NSEC_PER_MSEC,	/* EHCI_HRTIMER_START_UNLINK_INTR */
 	6 * NSEC_PER_MSEC,	/* EHCI_HRTIMER_ASYNC_UNLINKS */
 	10 * NSEC_PER_MSEC,	/* EHCI_HRTIMER_IAA_WATCHDOG */
 	10 * NSEC_PER_MSEC,	/* EHCI_HRTIMER_DISABLE_PERIODIC */
 	15 * NSEC_PER_MSEC,	/* EHCI_HRTIMER_DISABLE_ASYNC */
 	100 * NSEC_PER_MSEC,	/* EHCI_HRTIMER_IO_WATCHDOG */
 };

 /* Enable a pending hrtimer event */
 static void ehci_enable_event(struct ehci_hcd *ehci, unsigned event,
 		bool resched)
 {
 	ktime_t		*timeout = &ehci->hr_timeouts[event];

 	if (resched)
 		*timeout = ktime_add(ktime_get(), event_delays_ns[event]);
 	ehci->enabled_hrtimer_events |= (1 << event);

 	/* Track only the lowest-numbered pending event */
 	if (event < ehci->next_hrtimer_event) {
 		ehci->next_hrtimer_event = event;
 		hrtimer_start_range_ns(&ehci->hrtimer, *timeout,
 				NSEC_PER_MSEC, HRTIMER_MODE_ABS);
 	}
 }


 /* Poll the STS_ASS status bit; see when it agrees with CMD_ASE */
 static void ehci_poll_ASS(struct ehci_hcd *ehci)
 {
 	unsigned	actual, want;

 	/* Don't enable anything if the controller isn't running (e.g., died) */
 	if (ehci->rh_state != EHCI_RH_RUNNING)
 		return;

 	want = (ehci->command & CMD_ASE) ? STS_ASS : 0;
 	actual = ehci_readl(ehci, &ehci->regs->status) & STS_ASS;

 	if (want != actual) {

 		/* Poll again later, but give up after about 2-4 ms */
 		if (ehci->ASS_poll_count++ < 2) {
 			ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true);
 			return;
 		}
 		ehci_dbg(ehci, "Waited too long for the async schedule status (%x/%x), giving up\n",
 				want, actual);
 	}
 	ehci->ASS_poll_count = 0;

 	/* The status is up-to-date; restart or stop the schedule as needed */
 	if (want == 0) {	/* Stopped */
 		if (ehci->async_count > 0)
 			ehci_set_command_bit(ehci, CMD_ASE);

 	} else {		/* Running */
 		if (ehci->async_count == 0) {

 			/* Turn off the schedule after a while */
 			ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_ASYNC,
 					true);
 		}
 	}
 }

 /* Turn off the async schedule after a brief delay */
 static void ehci_disable_ASE(struct ehci_hcd *ehci)
 {
 	ehci_clear_command_bit(ehci, CMD_ASE);
 }


 /* Poll the STS_PSS status bit; see when it agrees with CMD_PSE */
 static void ehci_poll_PSS(struct ehci_hcd *ehci)
 {
 	unsigned	actual, want;

 	/* Don't do anything if the controller isn't running (e.g., died) */
 	if (ehci->rh_state != EHCI_RH_RUNNING)
 		return;

 	want = (ehci->command & CMD_PSE) ? STS_PSS : 0;
 	actual = ehci_readl(ehci, &ehci->regs->status) & STS_PSS;

 	if (want != actual) {

 		/* Poll again later, but give up after about 2-4 ms */
 		if (ehci->PSS_poll_count++ < 2) {
 			ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true);
 			return;
 		}
 		ehci_dbg(ehci, "Waited too long for the periodic schedule status (%x/%x), giving up\n",
 				want, actual);
 	}
 	ehci->PSS_poll_count = 0;

 	/* The status is up-to-date; restart or stop the schedule as needed */
 	if (want == 0) {	/* Stopped */
 		if (ehci->periodic_count > 0)
 			ehci_set_command_bit(ehci, CMD_PSE);

 	} else {		/* Running */
 		if (ehci->periodic_count == 0) {

 			/* Turn off the schedule after a while */
 			ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_PERIODIC,
 					true);
 		}
 	}
 }

 /* Turn off the periodic schedule after a brief delay */
 static void ehci_disable_PSE(struct ehci_hcd *ehci)
 {
 	ehci_clear_command_bit(ehci, CMD_PSE);
 }


 /* Poll the STS_HALT status bit; see when a dead controller stops */
 static void ehci_handle_controller_death(struct ehci_hcd *ehci)
 {
 	if (!(ehci_readl(ehci, &ehci->regs->status) & STS_HALT)) {

 		/* Give up after a few milliseconds */
 		if (ehci->died_poll_count++ < 5) {
 			/* Try again later */
 			ehci_enable_event(ehci, EHCI_HRTIMER_POLL_DEAD, true);
 			return;
 		}
 		ehci_warn(ehci, "Waited too long for the controller to stop, giving up\n");
 	}

 	/* Clean up the mess */
 	ehci->rh_state = EHCI_RH_HALTED;
 	ehci_writel(ehci, 0, &ehci->regs->configured_flag);
 	ehci_writel(ehci, 0, &ehci->regs->intr_enable);
 	ehci_work(ehci);
 	end_unlink_async(ehci);

 	/* Not in process context, so don't try to reset the controller */
 }

 /* start to unlink interrupt QHs  */
 static void ehci_handle_start_intr_unlinks(struct ehci_hcd *ehci)
 {
 	bool		stopped = (ehci->rh_state < EHCI_RH_RUNNING);

 	/*
 	 * Process all the QHs on the intr_unlink list that were added
 	 * before the current unlink cycle began.  The list is in
 	 * temporal order, so stop when we reach the first entry in the
 	 * current cycle.  But if the root hub isn't running then
 	 * process all the QHs on the list.
 	 */
 	while (!list_empty(&ehci->intr_unlink_wait)) {
 		struct ehci_qh	*qh;

 		qh = list_first_entry(&ehci->intr_unlink_wait,
 				struct ehci_qh, unlink_node);
 		if (!stopped && (qh->unlink_cycle ==
 				ehci->intr_unlink_wait_cycle))
 			break;
 		list_del_init(&qh->unlink_node);
 		qh->unlink_reason |= QH_UNLINK_QUEUE_EMPTY;
 		start_unlink_intr(ehci, qh);
 	}

 	/* Handle remaining entries later */
 	if (!list_empty(&ehci->intr_unlink_wait)) {
 		ehci_enable_event(ehci, EHCI_HRTIMER_START_UNLINK_INTR, true);
 		++ehci->intr_unlink_wait_cycle;
 	}
 }

 /* Handle unlinked interrupt QHs once they are gone from the hardware */
 static void ehci_handle_intr_unlinks(struct ehci_hcd *ehci)
 {
 	bool		stopped = (ehci->rh_state < EHCI_RH_RUNNING);

 	/*
 	 * Process all the QHs on the intr_unlink list that were added
 	 * before the current unlink cycle began.  The list is in
 	 * temporal order, so stop when we reach the first entry in the
 	 * current cycle.  But if the root hub isn't running then
 	 * process all the QHs on the list.
 	 */
 	ehci->intr_unlinking = true;
 	while (!list_empty(&ehci->intr_unlink)) {
 		struct ehci_qh	*qh;

 		qh = list_first_entry(&ehci->intr_unlink, struct ehci_qh,
 				unlink_node);
 		if (!stopped && qh->unlink_cycle == ehci->intr_unlink_cycle)
 			break;
 		list_del_init(&qh->unlink_node);
 		end_unlink_intr(ehci, qh);
 	}

 	/* Handle remaining entries later */
 	if (!list_empty(&ehci->intr_unlink)) {
 		ehci_enable_event(ehci, EHCI_HRTIMER_UNLINK_INTR, true);
 		++ehci->intr_unlink_cycle;
 	}
 	ehci->intr_unlinking = false;
 }


 /* Start another free-iTDs/siTDs cycle */
 static void start_free_itds(struct ehci_hcd *ehci)
 {
 	if (!(ehci->enabled_hrtimer_events & BIT(EHCI_HRTIMER_FREE_ITDS))) {
 		ehci->last_itd_to_free = list_entry(
 				ehci->cached_itd_list.prev,
 				struct ehci_itd, itd_list);
 		ehci->last_sitd_to_free = list_entry(
 				ehci->cached_sitd_list.prev,
 				struct ehci_sitd, sitd_list);
 		ehci_enable_event(ehci, EHCI_HRTIMER_FREE_ITDS, true);
 	}
 }

 /* Wait for controller to stop using old iTDs and siTDs */
 static void end_free_itds(struct ehci_hcd *ehci)
 {
 	struct ehci_itd		*itd, *n;
 	struct ehci_sitd	*sitd, *sn;

 	if (ehci->rh_state < EHCI_RH_RUNNING) {
 		ehci->last_itd_to_free = NULL;
 		ehci->last_sitd_to_free = NULL;
 	}

 	list_for_each_entry_safe(itd, n, &ehci->cached_itd_list, itd_list) {
 		list_del(&itd->itd_list);
 		dma_pool_free(ehci->itd_pool, itd, itd->itd_dma);
 		if (itd == ehci->last_itd_to_free)
 			break;
 	}
 	list_for_each_entry_safe(sitd, sn, &ehci->cached_sitd_list, sitd_list) {
 		list_del(&sitd->sitd_list);
 		dma_pool_free(ehci->sitd_pool, sitd, sitd->sitd_dma);
 		if (sitd == ehci->last_sitd_to_free)
 			break;
 	}

 	if (!list_empty(&ehci->cached_itd_list) ||
 			!list_empty(&ehci->cached_sitd_list))
 		start_free_itds(ehci);
 }


 /* Handle lost (or very late) IAA interrupts */
 static void ehci_iaa_watchdog(struct ehci_hcd *ehci)
 {
 	u32 cmd, status;

 	/*
 	 * Lost IAA irqs wedge things badly; seen first with a vt8235.
 	 * So we need this watchdog, but must protect it against both
 	 * (a) SMP races against real IAA firing and retriggering, and
 	 * (b) clean HC shutdown, when IAA watchdog was pending.
 	 */
 	if (!ehci->iaa_in_progress || ehci->rh_state != EHCI_RH_RUNNING)
 		return;

 	/* If we get here, IAA is *REALLY* late.  It's barely
 	 * conceivable that the system is so busy that CMD_IAAD
 	 * is still legitimately set, so let's be sure it's
 	 * clear before we read STS_IAA.  (The HC should clear
 	 * CMD_IAAD when it sets STS_IAA.)
 	 */
 	cmd = ehci_readl(ehci, &ehci->regs->command);

 	/*
 	 * If IAA is set here it either legitimately triggered
 	 * after the watchdog timer expired (_way_ late, so we'll
 	 * still count it as lost) ... or a silicon erratum:
 	 * - VIA seems to set IAA without triggering the IRQ;
 	 * - IAAD potentially cleared without setting IAA.
 	 */
 	status = ehci_readl(ehci, &ehci->regs->status);
 	if ((status & STS_IAA) || !(cmd & CMD_IAAD)) {
 		INCR(ehci->stats.lost_iaa);
 		ehci_writel(ehci, STS_IAA, &ehci->regs->status);
 	}

 	ehci_dbg(ehci, "IAA watchdog: status %x cmd %x\n", status, cmd);
 	end_iaa_cycle(ehci);
 }


 /* Enable the I/O watchdog, if appropriate */
 static void turn_on_io_watchdog(struct ehci_hcd *ehci)
 {
 	/* Not needed if the controller isn't running or it's already enabled */
 	if (ehci->rh_state != EHCI_RH_RUNNING ||
 			(ehci->enabled_hrtimer_events &
 				BIT(EHCI_HRTIMER_IO_WATCHDOG)))
 		return;

 	/*
 	 * Isochronous transfers always need the watchdog.
 	 * For other sorts we use it only if the flag is set.
 	 */
 	if (ehci->isoc_count > 0 || (ehci->need_io_watchdog &&
 			ehci->async_count + ehci->intr_count > 0))
 		ehci_enable_event(ehci, EHCI_HRTIMER_IO_WATCHDOG, true);
 }


 /*
  * Handler functions for the hrtimer event types.
  * Keep this array in the same order as the event types indexed by
  * enum ehci_hrtimer_event in ehci.h.
  */
 static void (*event_handlers[])(struct ehci_hcd *) = {
 	ehci_poll_ASS,			/* EHCI_HRTIMER_POLL_ASS */
 	ehci_poll_PSS,			/* EHCI_HRTIMER_POLL_PSS */
 	ehci_handle_controller_death,	/* EHCI_HRTIMER_POLL_DEAD */
 	ehci_handle_intr_unlinks,	/* EHCI_HRTIMER_UNLINK_INTR */
 	end_free_itds,			/* EHCI_HRTIMER_FREE_ITDS */
 	end_unlink_async,		/* EHCI_HRTIMER_ACTIVE_UNLINK */
 	ehci_handle_start_intr_unlinks,	/* EHCI_HRTIMER_START_UNLINK_INTR */
 	unlink_empty_async,		/* EHCI_HRTIMER_ASYNC_UNLINKS */
 	ehci_iaa_watchdog,		/* EHCI_HRTIMER_IAA_WATCHDOG */
 	ehci_disable_PSE,		/* EHCI_HRTIMER_DISABLE_PERIODIC */
 	ehci_disable_ASE,		/* EHCI_HRTIMER_DISABLE_ASYNC */
 	ehci_work,			/* EHCI_HRTIMER_IO_WATCHDOG */
 };

 static enum hrtimer_restart ehci_hrtimer_func(struct hrtimer *t)
 {
 	struct ehci_hcd	*ehci = container_of(t, struct ehci_hcd, hrtimer);
 	ktime_t		now;
 	unsigned long	events;
 	unsigned long	flags;
 	unsigned	e;

 	spin_lock_irqsave(&ehci->lock, flags);

 	events = ehci->enabled_hrtimer_events;
 	ehci->enabled_hrtimer_events = 0;
 	ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT;

 	/*
 	 * Check each pending event.  If its time has expired, handle
 	 * the event; otherwise re-enable it.
 	 */
 	now = ktime_get();
 	for_each_set_bit(e, &events, EHCI_HRTIMER_NUM_EVENTS) {
 		if (ktime_compare(now, ehci->hr_timeouts[e]) >= 0)
 			event_handlers[e](ehci);
 		else
 			ehci_enable_event(ehci, e, false);
 	}

 	spin_unlock_irqrestore(&ehci->lock, flags);
 	return HRTIMER_NORESTART;
 }
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* Copyright (C) 2012 by Alan Stern
	*/

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

	/-------------------------------------------------------------------------/

	/* Set a bit in the USBCMD register */
	static void ehci_set_command_bit(struct ehci_hcd *ehci, u32 bit)
	{
	ehci->command \|= bit;
	ehci_writel(ehci, ehci->command, &ehci->regs->command);

	/* unblock posted write */
	ehci_readl(ehci, &ehci->regs->command);
	}

	/* Clear a bit in the USBCMD register */
	static void ehci_clear_command_bit(struct ehci_hcd *ehci, u32 bit)
	{
	ehci->command &= ~bit;
	ehci_writel(ehci, ehci->command, &ehci->regs->command);

	/* unblock posted write */
	ehci_readl(ehci, &ehci->regs->command);
	}

	/-------------------------------------------------------------------------/

	/*
	* EHCI timer support... Now using hrtimers.
	*
	* Lots of different events are triggered from ehci->hrtimer. Whenever
	* the timer routine runs, it checks each possible event; events that are
	* currently enabled and whose expiration time has passed get handled.
	* The set of enabled events is stored as a collection of bitflags in
	* ehci->enabled_hrtimer_events, and they are numbered in order of
	* increasing delay values (ranging between 1 ms and 100 ms).
	*
	* Rather than implementing a sorted list or tree of all pending events,
	* we keep track only of the lowest-numbered pending event, in
	* ehci->next_hrtimer_event. Whenever ehci->hrtimer gets restarted, its
	* expiration time is set to the timeout value for this event.
	*
	* As a result, events might not get handled right away; the actual delay
	* could be anywhere up to twice the requested delay. This doesn't
	* matter, because none of the events are especially time-critical. The
	* ones that matter most all have a delay of 1 ms, so they will be
	* handled after 2 ms at most, which is okay. In addition to this, we
	* allow for an expiration range of 1 ms.
	*/

	/*
	* Delay lengths for the hrtimer event types.
	* Keep this list sorted by delay length, in the same order as
	* the event types indexed by enum ehci_hrtimer_event in ehci.h.
	*/
	static unsigned event_delays_ns[] = {
	1 * NSEC_PER_MSEC, /* EHCI_HRTIMER_POLL_ASS */
	1 * NSEC_PER_MSEC, /* EHCI_HRTIMER_POLL_PSS */
	1 * NSEC_PER_MSEC, /* EHCI_HRTIMER_POLL_DEAD */
	1125 * NSEC_PER_USEC, /* EHCI_HRTIMER_UNLINK_INTR */
	2 * NSEC_PER_MSEC, /* EHCI_HRTIMER_FREE_ITDS */
	2 * NSEC_PER_MSEC, /* EHCI_HRTIMER_ACTIVE_UNLINK */
	5 * NSEC_PER_MSEC, /* EHCI_HRTIMER_START_UNLINK_INTR */
	6 * NSEC_PER_MSEC, /* EHCI_HRTIMER_ASYNC_UNLINKS */
	10 * NSEC_PER_MSEC, /* EHCI_HRTIMER_IAA_WATCHDOG */
	10 * NSEC_PER_MSEC, /* EHCI_HRTIMER_DISABLE_PERIODIC */
	15 * NSEC_PER_MSEC, /* EHCI_HRTIMER_DISABLE_ASYNC */
	100 * NSEC_PER_MSEC, /* EHCI_HRTIMER_IO_WATCHDOG */
	};

	/* Enable a pending hrtimer event */
	static void ehci_enable_event(struct ehci_hcd *ehci, unsigned event,
	bool resched)
	{
	ktime_t *timeout = &ehci->hr_timeouts[event];

	if (resched)
	*timeout = ktime_add(ktime_get(), event_delays_ns[event]);
	ehci->enabled_hrtimer_events \|= (1 << event);

	/* Track only the lowest-numbered pending event */
	if (event < ehci->next_hrtimer_event) {
	ehci->next_hrtimer_event = event;
	hrtimer_start_range_ns(&ehci->hrtimer, *timeout,
	NSEC_PER_MSEC, HRTIMER_MODE_ABS);
	}
	}


	/* Poll the STS_ASS status bit; see when it agrees with CMD_ASE */
	static void ehci_poll_ASS(struct ehci_hcd *ehci)
	{
	unsigned actual, want;

	/* Don't enable anything if the controller isn't running (e.g., died) */
	if (ehci->rh_state != EHCI_RH_RUNNING)
	return;

	want = (ehci->command & CMD_ASE) ? STS_ASS : 0;
	actual = ehci_readl(ehci, &ehci->regs->status) & STS_ASS;

	if (want != actual) {

	/* Poll again later, but give up after about 2-4 ms */
	if (ehci->ASS_poll_count++ < 2) {
	ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true);
	return;
	}
	ehci_dbg(ehci, "Waited too long for the async schedule status (%x/%x), giving up\n",
	want, actual);
	}
	ehci->ASS_poll_count = 0;

	/* The status is up-to-date; restart or stop the schedule as needed */
	if (want == 0) { /* Stopped */
	if (ehci->async_count > 0)
	ehci_set_command_bit(ehci, CMD_ASE);

	} else { /* Running */
	if (ehci->async_count == 0) {

	/* Turn off the schedule after a while */
	ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_ASYNC,
	true);
	}
	}
	}

	/* Turn off the async schedule after a brief delay */
	static void ehci_disable_ASE(struct ehci_hcd *ehci)
	{
	ehci_clear_command_bit(ehci, CMD_ASE);
	}


	/* Poll the STS_PSS status bit; see when it agrees with CMD_PSE */
	static void ehci_poll_PSS(struct ehci_hcd *ehci)
	{
	unsigned actual, want;

	/* Don't do anything if the controller isn't running (e.g., died) */
	if (ehci->rh_state != EHCI_RH_RUNNING)
	return;

	want = (ehci->command & CMD_PSE) ? STS_PSS : 0;
	actual = ehci_readl(ehci, &ehci->regs->status) & STS_PSS;

	if (want != actual) {

	/* Poll again later, but give up after about 2-4 ms */
	if (ehci->PSS_poll_count++ < 2) {
	ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true);
	return;
	}
	ehci_dbg(ehci, "Waited too long for the periodic schedule status (%x/%x), giving up\n",
	want, actual);
	}
	ehci->PSS_poll_count = 0;

	/* The status is up-to-date; restart or stop the schedule as needed */
	if (want == 0) { /* Stopped */
	if (ehci->periodic_count > 0)
	ehci_set_command_bit(ehci, CMD_PSE);

	} else { /* Running */
	if (ehci->periodic_count == 0) {

	/* Turn off the schedule after a while */
	ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_PERIODIC,
	true);
	}
	}
	}

	/* Turn off the periodic schedule after a brief delay */
	static void ehci_disable_PSE(struct ehci_hcd *ehci)
	{
	ehci_clear_command_bit(ehci, CMD_PSE);
	}


	/* Poll the STS_HALT status bit; see when a dead controller stops */
	static void ehci_handle_controller_death(struct ehci_hcd *ehci)
	{
	if (!(ehci_readl(ehci, &ehci->regs->status) & STS_HALT)) {

	/* Give up after a few milliseconds */
	if (ehci->died_poll_count++ < 5) {
	/* Try again later */
	ehci_enable_event(ehci, EHCI_HRTIMER_POLL_DEAD, true);
	return;
	}
	ehci_warn(ehci, "Waited too long for the controller to stop, giving up\n");
	}

	/* Clean up the mess */
	ehci->rh_state = EHCI_RH_HALTED;
	ehci_writel(ehci, 0, &ehci->regs->configured_flag);
	ehci_writel(ehci, 0, &ehci->regs->intr_enable);
	ehci_work(ehci);
	end_unlink_async(ehci);

	/* Not in process context, so don't try to reset the controller */
	}

	/* start to unlink interrupt QHs */
	static void ehci_handle_start_intr_unlinks(struct ehci_hcd *ehci)
	{
	bool stopped = (ehci->rh_state < EHCI_RH_RUNNING);

	/*
	* Process all the QHs on the intr_unlink list that were added
	* before the current unlink cycle began. The list is in
	* temporal order, so stop when we reach the first entry in the
	* current cycle. But if the root hub isn't running then
	* process all the QHs on the list.
	*/
	while (!list_empty(&ehci->intr_unlink_wait)) {
	struct ehci_qh *qh;

	qh = list_first_entry(&ehci->intr_unlink_wait,
	struct ehci_qh, unlink_node);
	if (!stopped && (qh->unlink_cycle ==
	ehci->intr_unlink_wait_cycle))
	break;
	list_del_init(&qh->unlink_node);
	qh->unlink_reason \|= QH_UNLINK_QUEUE_EMPTY;
	start_unlink_intr(ehci, qh);
	}

	/* Handle remaining entries later */
	if (!list_empty(&ehci->intr_unlink_wait)) {
	ehci_enable_event(ehci, EHCI_HRTIMER_START_UNLINK_INTR, true);
	++ehci->intr_unlink_wait_cycle;
	}
	}

	/* Handle unlinked interrupt QHs once they are gone from the hardware */
	static void ehci_handle_intr_unlinks(struct ehci_hcd *ehci)
	{
	bool stopped = (ehci->rh_state < EHCI_RH_RUNNING);

	/*
	* Process all the QHs on the intr_unlink list that were added
	* before the current unlink cycle began. The list is in
	* temporal order, so stop when we reach the first entry in the
	* current cycle. But if the root hub isn't running then
	* process all the QHs on the list.
	*/
	ehci->intr_unlinking = true;
	while (!list_empty(&ehci->intr_unlink)) {
	struct ehci_qh *qh;

	qh = list_first_entry(&ehci->intr_unlink, struct ehci_qh,
	unlink_node);
	if (!stopped && qh->unlink_cycle == ehci->intr_unlink_cycle)
	break;
	list_del_init(&qh->unlink_node);
	end_unlink_intr(ehci, qh);
	}

	/* Handle remaining entries later */
	if (!list_empty(&ehci->intr_unlink)) {
	ehci_enable_event(ehci, EHCI_HRTIMER_UNLINK_INTR, true);
	++ehci->intr_unlink_cycle;
	}
	ehci->intr_unlinking = false;
	}


	/* Start another free-iTDs/siTDs cycle */
	static void start_free_itds(struct ehci_hcd *ehci)
	{
	if (!(ehci->enabled_hrtimer_events & BIT(EHCI_HRTIMER_FREE_ITDS))) {
	ehci->last_itd_to_free = list_entry(
	ehci->cached_itd_list.prev,
	struct ehci_itd, itd_list);
	ehci->last_sitd_to_free = list_entry(
	ehci->cached_sitd_list.prev,
	struct ehci_sitd, sitd_list);
	ehci_enable_event(ehci, EHCI_HRTIMER_FREE_ITDS, true);
	}
	}

	/* Wait for controller to stop using old iTDs and siTDs */
	static void end_free_itds(struct ehci_hcd *ehci)
	{
	struct ehci_itd itd, n;
	struct ehci_sitd sitd, sn;

	if (ehci->rh_state < EHCI_RH_RUNNING) {
	ehci->last_itd_to_free = NULL;
	ehci->last_sitd_to_free = NULL;
	}

	list_for_each_entry_safe(itd, n, &ehci->cached_itd_list, itd_list) {
	list_del(&itd->itd_list);
	dma_pool_free(ehci->itd_pool, itd, itd->itd_dma);
	if (itd == ehci->last_itd_to_free)
	break;
	}
	list_for_each_entry_safe(sitd, sn, &ehci->cached_sitd_list, sitd_list) {
	list_del(&sitd->sitd_list);
	dma_pool_free(ehci->sitd_pool, sitd, sitd->sitd_dma);
	if (sitd == ehci->last_sitd_to_free)
	break;
	}

	if (!list_empty(&ehci->cached_itd_list) \|\|
	!list_empty(&ehci->cached_sitd_list))
	start_free_itds(ehci);
	}


	/* Handle lost (or very late) IAA interrupts */
	static void ehci_iaa_watchdog(struct ehci_hcd *ehci)
	{
	u32 cmd, status;

	/*
	* Lost IAA irqs wedge things badly; seen first with a vt8235.
	* So we need this watchdog, but must protect it against both
	* (a) SMP races against real IAA firing and retriggering, and
	* (b) clean HC shutdown, when IAA watchdog was pending.
	*/
	if (!ehci->iaa_in_progress \|\| ehci->rh_state != EHCI_RH_RUNNING)
	return;

	/* If we get here, IAA is REALLY late. It's barely
	* conceivable that the system is so busy that CMD_IAAD
	* is still legitimately set, so let's be sure it's
	* clear before we read STS_IAA. (The HC should clear
	* CMD_IAAD when it sets STS_IAA.)
	*/
	cmd = ehci_readl(ehci, &ehci->regs->command);

	/*
	* If IAA is set here it either legitimately triggered
	* after the watchdog timer expired (_way_ late, so we'll
	* still count it as lost) ... or a silicon erratum:
	* - VIA seems to set IAA without triggering the IRQ;
	* - IAAD potentially cleared without setting IAA.
	*/
	status = ehci_readl(ehci, &ehci->regs->status);
	if ((status & STS_IAA) \|\| !(cmd & CMD_IAAD)) {
	INCR(ehci->stats.lost_iaa);
	ehci_writel(ehci, STS_IAA, &ehci->regs->status);
	}

	ehci_dbg(ehci, "IAA watchdog: status %x cmd %x\n", status, cmd);
	end_iaa_cycle(ehci);
	}


	/* Enable the I/O watchdog, if appropriate */
	static void turn_on_io_watchdog(struct ehci_hcd *ehci)
	{
	/* Not needed if the controller isn't running or it's already enabled */
	if (ehci->rh_state != EHCI_RH_RUNNING \|\|
	(ehci->enabled_hrtimer_events &
	BIT(EHCI_HRTIMER_IO_WATCHDOG)))
	return;

	/*
	* Isochronous transfers always need the watchdog.
	* For other sorts we use it only if the flag is set.
	*/
	if (ehci->isoc_count > 0 \|\| (ehci->need_io_watchdog &&
	ehci->async_count + ehci->intr_count > 0))
	ehci_enable_event(ehci, EHCI_HRTIMER_IO_WATCHDOG, true);
	}


	/*
	* Handler functions for the hrtimer event types.
	* Keep this array in the same order as the event types indexed by
	* enum ehci_hrtimer_event in ehci.h.
	*/
	static void (event_handlers[])(struct ehci_hcd ) = {
	ehci_poll_ASS, /* EHCI_HRTIMER_POLL_ASS */
	ehci_poll_PSS, /* EHCI_HRTIMER_POLL_PSS */
	ehci_handle_controller_death, /* EHCI_HRTIMER_POLL_DEAD */
	ehci_handle_intr_unlinks, /* EHCI_HRTIMER_UNLINK_INTR */
	end_free_itds, /* EHCI_HRTIMER_FREE_ITDS */
	end_unlink_async, /* EHCI_HRTIMER_ACTIVE_UNLINK */
	ehci_handle_start_intr_unlinks, /* EHCI_HRTIMER_START_UNLINK_INTR */
	unlink_empty_async, /* EHCI_HRTIMER_ASYNC_UNLINKS */
	ehci_iaa_watchdog, /* EHCI_HRTIMER_IAA_WATCHDOG */
	ehci_disable_PSE, /* EHCI_HRTIMER_DISABLE_PERIODIC */
	ehci_disable_ASE, /* EHCI_HRTIMER_DISABLE_ASYNC */
	ehci_work, /* EHCI_HRTIMER_IO_WATCHDOG */
	};

	static enum hrtimer_restart ehci_hrtimer_func(struct hrtimer *t)
	{
	struct ehci_hcd *ehci = container_of(t, struct ehci_hcd, hrtimer);
	ktime_t now;
	unsigned long events;
	unsigned long flags;
	unsigned e;

	spin_lock_irqsave(&ehci->lock, flags);

	events = ehci->enabled_hrtimer_events;
	ehci->enabled_hrtimer_events = 0;
	ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT;

	/*
	* Check each pending event. If its time has expired, handle
	* the event; otherwise re-enable it.
	*/
	now = ktime_get();
	for_each_set_bit(e, &events, EHCI_HRTIMER_NUM_EVENTS) {
	if (ktime_compare(now, ehci->hr_timeouts[e]) >= 0)
	event_handlers[e](ehci);
	else
	ehci_enable_event(ehci, e, false);
	}

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