1 files changed, 106 insertions, 0 deletions

diff --git a/drivers/usb/host/ehci-timer.c b/drivers/usb/host/ehci-timer.c
new file mode 100644
index 000000000000..f6279e2883a8
--- /dev/null
+++ b/drivers/usb/host/ehci-timer.c
@@ -0,0 +1,106 @@
+/*
+ * 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 */
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * 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[] = {
+};
+
+/* 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);
+        }
+}
+
+
+/*
+ * 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 *) = {
+};
+
+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;
+}