/*
* Copyright (C) 2012 by Alan Stern
*
* 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.
*/
/* 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 */
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(),
ktime_set(0, 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 20 ms */
if (ehci->ASS_poll_count++ < 20) {
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 20 ms */
if (ehci->PSS_poll_count++ < 20) {
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 */
}
/* 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 (ehci->intr_unlink) {
struct ehci_qh *qh = ehci->intr_unlink;
if (!stopped && qh->unlink_cycle == ehci->intr_unlink_cycle)
break;
ehci->intr_unlink = qh->unlink_next;
qh->unlink_next = NULL;
end_unlink_intr(ehci, qh);
}
/* Handle remaining entries later */
if (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)
{
if (ehci->rh_state != EHCI_RH_RUNNING)
return;
/*
* 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->async_iaa) {
u32 cmd, status;
/* 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)) {
COUNT(ehci->stats.lost_iaa);
ehci_writel(ehci, STS_IAA, &ehci->regs->status);
}
ehci_vdbg(ehci, "IAA watchdog: status %x cmd %x\n",
status, cmd);
end_unlink_async(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 */
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 (now.tv64 >= ehci->hr_timeouts[e].tv64)
event_handlers[e](ehci);
else
ehci_enable_event(ehci, e, false);
}
spin_unlock_irqrestore(&ehci->lock, flags);
return HRTIMER_NORESTART;
}
