1 files changed, 247 insertions, 0 deletions
diff --git a/drivers/base/power/wakeup.c b/drivers/base/power/wakeup.c
new file mode 100644
index 000000000000..eb594facfc3f
--- /dev/null
+++ b/drivers/base/power/wakeup.c
@@ -0,0 +1,247 @@
+/*
+ * drivers/base/power/wakeup.c - System wakeup events framework
+ *
+ * Copyright (c) 2010 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
+ *
+ * This file is released under the GPLv2.
+ */
+
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/capability.h>
+#include <linux/suspend.h>
+#include <linux/pm.h>
+
+/*
+ * If set, the suspend/hibernate code will abort transitions to a sleep state
+ * if wakeup events are registered during or immediately before the transition.
+ */
+bool events_check_enabled;
+
+/* The counter of registered wakeup events. */
+static unsigned long event_count;
+/* A preserved old value of event_count. */
+static unsigned long saved_event_count;
+/* The counter of wakeup events being processed. */
+static unsigned long events_in_progress;
+
+static DEFINE_SPINLOCK(events_lock);
+
+static void pm_wakeup_timer_fn(unsigned long data);
+
+static DEFINE_TIMER(events_timer, pm_wakeup_timer_fn, 0, 0);
+static unsigned long events_timer_expires;
+
+/*
+ * The functions below use the observation that each wakeup event starts a
+ * period in which the system should not be suspended.  The moment this period
+ * will end depends on how the wakeup event is going to be processed after being
+ * detected and all of the possible cases can be divided into two distinct
+ * groups.
+ *
+ * First, a wakeup event may be detected by the same functional unit that will
+ * carry out the entire processing of it and possibly will pass it to user space
+ * for further processing.  In that case the functional unit that has detected
+ * the event may later "close" the "no suspend" period associated with it
+ * directly as soon as it has been dealt with.  The pair of pm_stay_awake() and
+ * pm_relax(), balanced with each other, is supposed to be used in such
+ * situations.
+ *
+ * Second, a wakeup event may be detected by one functional unit and processed
+ * by another one.  In that case the unit that has detected it cannot really
+ * "close" the "no suspend" period associated with it, unless it knows in
+ * advance what's going to happen to the event during processing.  This
+ * knowledge, however, may not be available to it, so it can simply specify time
+ * to wait before the system can be suspended and pass it as the second
+ * argument of pm_wakeup_event().
+ */
+
+/**
+ * pm_stay_awake - Notify the PM core that a wakeup event is being processed.
+ * @dev: Device the wakeup event is related to.
+ *
+ * Notify the PM core of a wakeup event (signaled by @dev) by incrementing the
+ * counter of wakeup events being processed.  If @dev is not NULL, the counter
+ * of wakeup events related to @dev is incremented too.
+ *
+ * Call this function after detecting of a wakeup event if pm_relax() is going
+ * to be called directly after processing the event (and possibly passing it to
+ * user space for further processing).
+ *
+ * It is safe to call this function from interrupt context.
+ */
+void pm_stay_awake(struct device *dev)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&events_lock, flags);
+	if (dev)
+		dev->power.wakeup_count++;
+
+	events_in_progress++;
+	spin_unlock_irqrestore(&events_lock, flags);
+}
+
+/**
+ * pm_relax - Notify the PM core that processing of a wakeup event has ended.
+ *
+ * Notify the PM core that a wakeup event has been processed by decrementing
+ * the counter of wakeup events being processed and incrementing the counter
+ * of registered wakeup events.
+ *
+ * Call this function for wakeup events whose processing started with calling
+ * pm_stay_awake().
+ *
+ * It is safe to call it from interrupt context.
+ */
+void pm_relax(void)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&events_lock, flags);
+	if (events_in_progress) {
+		events_in_progress--;
+		event_count++;
+	}
+	spin_unlock_irqrestore(&events_lock, flags);
+}
+
+/**
+ * pm_wakeup_timer_fn - Delayed finalization of a wakeup event.
+ *
+ * Decrease the counter of wakeup events being processed after it was increased
+ * by pm_wakeup_event().
+ */
+static void pm_wakeup_timer_fn(unsigned long data)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&events_lock, flags);
+	if (events_timer_expires
+	    && time_before_eq(events_timer_expires, jiffies)) {
+		events_in_progress--;
+		events_timer_expires = 0;
+	}
+	spin_unlock_irqrestore(&events_lock, flags);
+}
+
+/**
+ * pm_wakeup_event - Notify the PM core of a wakeup event.
+ * @dev: Device the wakeup event is related to.
+ * @msec: Anticipated event processing time (in milliseconds).
+ *
+ * Notify the PM core of a wakeup event (signaled by @dev) that will take
+ * approximately @msec milliseconds to be processed by the kernel.  Increment
+ * the counter of registered wakeup events and (if @msec is nonzero) set up
+ * the wakeup events timer to execute pm_wakeup_timer_fn() in future (if the
+ * timer has not been set up already, increment the counter of wakeup events
+ * being processed).  If @dev is not NULL, the counter of wakeup events related
+ * to @dev is incremented too.
+ *
+ * It is safe to call this function from interrupt context.
+ */
+void pm_wakeup_event(struct device *dev, unsigned int msec)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&events_lock, flags);
+	event_count++;
+	if (dev)
+		dev->power.wakeup_count++;
+
+	if (msec) {
+		unsigned long expires;
+
+		expires = jiffies + msecs_to_jiffies(msec);
+		if (!expires)
+			expires = 1;
+
+		if (!events_timer_expires
+		    || time_after(expires, events_timer_expires)) {
+			if (!events_timer_expires)
+				events_in_progress++;
+
+			mod_timer(&events_timer, expires);
+			events_timer_expires = expires;
+		}
+	}
+	spin_unlock_irqrestore(&events_lock, flags);
+}
+
+/**
+ * pm_check_wakeup_events - Check for new wakeup events.
+ *
+ * Compare the current number of registered wakeup events with its preserved
+ * value from the past to check if new wakeup events have been registered since
+ * the old value was stored.  Check if the current number of wakeup events being
+ * processed is zero.
+ */
+bool pm_check_wakeup_events(void)
+{
+	unsigned long flags;
+	bool ret = true;
+
+	spin_lock_irqsave(&events_lock, flags);
+	if (events_check_enabled) {
+		ret = (event_count == saved_event_count) && !events_in_progress;
+		events_check_enabled = ret;
+	}
+	spin_unlock_irqrestore(&events_lock, flags);
+	return ret;
+}
+
+/**
+ * pm_get_wakeup_count - Read the number of registered wakeup events.
+ * @count: Address to store the value at.
+ *
+ * Store the number of registered wakeup events at the address in @count.  Block
+ * if the current number of wakeup events being processed is nonzero.
+ *
+ * Return false if the wait for the number of wakeup events being processed to
+ * drop down to zero has been interrupted by a signal (and the current number
+ * of wakeup events being processed is still nonzero).  Otherwise return true.
+ */
+bool pm_get_wakeup_count(unsigned long *count)
+{
+	bool ret;
+
+	spin_lock_irq(&events_lock);
+	if (capable(CAP_SYS_ADMIN))
+		events_check_enabled = false;
+
+	while (events_in_progress && !signal_pending(current)) {
+		spin_unlock_irq(&events_lock);
+
+		schedule_timeout_interruptible(msecs_to_jiffies(100));
+
+		spin_lock_irq(&events_lock);
+	}
+	*count = event_count;
+	ret = !events_in_progress;
+	spin_unlock_irq(&events_lock);
+	return ret;
+}
+
+/**
+ * pm_save_wakeup_count - Save the current number of registered wakeup events.
+ * @count: Value to compare with the current number of registered wakeup events.
+ *
+ * If @count is equal to the current number of registered wakeup events and the
+ * current number of wakeup events being processed is zero, store @count as the
+ * old number of registered wakeup events to be used by pm_check_wakeup_events()
+ * and return true.  Otherwise return false.
+ */
+bool pm_save_wakeup_count(unsigned long count)
+{
+	bool ret = false;
+
+	spin_lock_irq(&events_lock);
+	if (count == event_count && !events_in_progress) {
+		saved_event_count = count;
+		events_check_enabled = true;
+		ret = true;
+	}
+	spin_unlock_irq(&events_lock);
+	return ret;
+}