staging: android-alarm: Add android alarm driver & in-kernel alarm interface

Drivers can now create alarms that will use an hrtimer while the
system is running and the rtc to wake up from suspend.

CC: Arve Hjønnevåg <arve@android.com>
CC: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Arve Hjønnevåg <arve@android.com>
[Fold and move alarm driver and interface to staging,
 fix whitespace issue, drop kconfig & make file changes
 as it currently doesn't build  -jstultz]
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 978 insertions, 0 deletions

diff --git a/drivers/staging/android/alarm-dev.c b/drivers/staging/android/alarm-dev.c
new file mode 100644
index 000000000000..ae56961f9c85
--- /dev/null
+++ b/drivers/staging/android/alarm-dev.c
@@ -0,0 +1,286 @@
+/* drivers/rtc/alarm-dev.c
+ *
+ * Copyright (C) 2007-2009 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#include <asm/mach/time.h>
+#include <linux/device.h>
+#include <linux/miscdevice.h>
+#include <linux/fs.h>
+#include <linux/platform_device.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/sysdev.h>
+#include <linux/uaccess.h>
+#include <linux/wakelock.h>
+#include "android_alarm.h"
+
+#define ANDROID_ALARM_PRINT_INFO (1U << 0)
+#define ANDROID_ALARM_PRINT_IO (1U << 1)
+#define ANDROID_ALARM_PRINT_INT (1U << 2)
+
+static int debug_mask = ANDROID_ALARM_PRINT_INFO;
+module_param_named(debug_mask, debug_mask, int, S_IRUGO | S_IWUSR | S_IWGRP);
+
+#define pr_alarm(debug_level_mask, args...) \
+	do { \
+		if (debug_mask & ANDROID_ALARM_PRINT_##debug_level_mask) { \
+			pr_info(args); \
+		} \
+	} while (0)
+
+#define ANDROID_ALARM_WAKEUP_MASK ( \
+	ANDROID_ALARM_RTC_WAKEUP_MASK | \
+	ANDROID_ALARM_ELAPSED_REALTIME_WAKEUP_MASK)
+
+/* support old usespace code */
+#define ANDROID_ALARM_SET_OLD               _IOW('a', 2, time_t) /* set alarm */
+#define ANDROID_ALARM_SET_AND_WAIT_OLD      _IOW('a', 3, time_t)
+
+static int alarm_opened;
+static DEFINE_SPINLOCK(alarm_slock);
+static struct wake_lock alarm_wake_lock;
+static DECLARE_WAIT_QUEUE_HEAD(alarm_wait_queue);
+static uint32_t alarm_pending;
+static uint32_t alarm_enabled;
+static uint32_t wait_pending;
+
+static struct alarm alarms[ANDROID_ALARM_TYPE_COUNT];
+
+static long alarm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	int rv = 0;
+	unsigned long flags;
+	struct timespec new_alarm_time;
+	struct timespec new_rtc_time;
+	struct timespec tmp_time;
+	enum android_alarm_type alarm_type = ANDROID_ALARM_IOCTL_TO_TYPE(cmd);
+	uint32_t alarm_type_mask = 1U << alarm_type;
+
+	if (alarm_type >= ANDROID_ALARM_TYPE_COUNT)
+		return -EINVAL;
+
+	if (ANDROID_ALARM_BASE_CMD(cmd) != ANDROID_ALARM_GET_TIME(0)) {
+		if ((file->f_flags & O_ACCMODE) == O_RDONLY)
+			return -EPERM;
+		if (file->private_data == NULL &&
+		    cmd != ANDROID_ALARM_SET_RTC) {
+			spin_lock_irqsave(&alarm_slock, flags);
+			if (alarm_opened) {
+				spin_unlock_irqrestore(&alarm_slock, flags);
+				return -EBUSY;
+			}
+			alarm_opened = 1;
+			file->private_data = (void *)1;
+			spin_unlock_irqrestore(&alarm_slock, flags);
+		}
+	}
+
+	switch (ANDROID_ALARM_BASE_CMD(cmd)) {
+	case ANDROID_ALARM_CLEAR(0):
+		spin_lock_irqsave(&alarm_slock, flags);
+		pr_alarm(IO, "alarm %d clear\n", alarm_type);
+		alarm_try_to_cancel(&alarms[alarm_type]);
+		if (alarm_pending) {
+			alarm_pending &= ~alarm_type_mask;
+			if (!alarm_pending && !wait_pending)
+				wake_unlock(&alarm_wake_lock);
+		}
+		alarm_enabled &= ~alarm_type_mask;
+		spin_unlock_irqrestore(&alarm_slock, flags);
+		break;
+
+	case ANDROID_ALARM_SET_OLD:
+	case ANDROID_ALARM_SET_AND_WAIT_OLD:
+		if (get_user(new_alarm_time.tv_sec, (int __user *)arg)) {
+			rv = -EFAULT;
+			goto err1;
+		}
+		new_alarm_time.tv_nsec = 0;
+		goto from_old_alarm_set;
+
+	case ANDROID_ALARM_SET_AND_WAIT(0):
+	case ANDROID_ALARM_SET(0):
+		if (copy_from_user(&new_alarm_time, (void __user *)arg,
+		    sizeof(new_alarm_time))) {
+			rv = -EFAULT;
+			goto err1;
+		}
+from_old_alarm_set:
+		spin_lock_irqsave(&alarm_slock, flags);
+		pr_alarm(IO, "alarm %d set %ld.%09ld\n", alarm_type,
+			new_alarm_time.tv_sec, new_alarm_time.tv_nsec);
+		alarm_enabled |= alarm_type_mask;
+		alarm_start_range(&alarms[alarm_type],
+			timespec_to_ktime(new_alarm_time),
+			timespec_to_ktime(new_alarm_time));
+		spin_unlock_irqrestore(&alarm_slock, flags);
+		if (ANDROID_ALARM_BASE_CMD(cmd) != ANDROID_ALARM_SET_AND_WAIT(0)
+		    && cmd != ANDROID_ALARM_SET_AND_WAIT_OLD)
+			break;
+		/* fall though */
+	case ANDROID_ALARM_WAIT:
+		spin_lock_irqsave(&alarm_slock, flags);
+		pr_alarm(IO, "alarm wait\n");
+		if (!alarm_pending && wait_pending) {
+			wake_unlock(&alarm_wake_lock);
+			wait_pending = 0;
+		}
+		spin_unlock_irqrestore(&alarm_slock, flags);
+		rv = wait_event_interruptible(alarm_wait_queue, alarm_pending);
+		if (rv)
+			goto err1;
+		spin_lock_irqsave(&alarm_slock, flags);
+		rv = alarm_pending;
+		wait_pending = 1;
+		alarm_pending = 0;
+		spin_unlock_irqrestore(&alarm_slock, flags);
+		break;
+	case ANDROID_ALARM_SET_RTC:
+		if (copy_from_user(&new_rtc_time, (void __user *)arg,
+		    sizeof(new_rtc_time))) {
+			rv = -EFAULT;
+			goto err1;
+		}
+		rv = alarm_set_rtc(new_rtc_time);
+		spin_lock_irqsave(&alarm_slock, flags);
+		alarm_pending |= ANDROID_ALARM_TIME_CHANGE_MASK;
+		wake_up(&alarm_wait_queue);
+		spin_unlock_irqrestore(&alarm_slock, flags);
+		if (rv < 0)
+			goto err1;
+		break;
+	case ANDROID_ALARM_GET_TIME(0):
+		switch (alarm_type) {
+		case ANDROID_ALARM_RTC_WAKEUP:
+		case ANDROID_ALARM_RTC:
+			getnstimeofday(&tmp_time);
+			break;
+		case ANDROID_ALARM_ELAPSED_REALTIME_WAKEUP:
+		case ANDROID_ALARM_ELAPSED_REALTIME:
+			tmp_time =
+				ktime_to_timespec(alarm_get_elapsed_realtime());
+			break;
+		case ANDROID_ALARM_TYPE_COUNT:
+		case ANDROID_ALARM_SYSTEMTIME:
+			ktime_get_ts(&tmp_time);
+			break;
+		}
+		if (copy_to_user((void __user *)arg, &tmp_time,
+		    sizeof(tmp_time))) {
+			rv = -EFAULT;
+			goto err1;
+		}
+		break;
+
+	default:
+		rv = -EINVAL;
+		goto err1;
+	}
+err1:
+	return rv;
+}
+
+static int alarm_open(struct inode *inode, struct file *file)
+{
+	file->private_data = NULL;
+	return 0;
+}
+
+static int alarm_release(struct inode *inode, struct file *file)
+{
+	int i;
+	unsigned long flags;
+
+	spin_lock_irqsave(&alarm_slock, flags);
+	if (file->private_data != 0) {
+		for (i = 0; i < ANDROID_ALARM_TYPE_COUNT; i++) {
+			uint32_t alarm_type_mask = 1U << i;
+			if (alarm_enabled & alarm_type_mask) {
+				pr_alarm(INFO, "alarm_release: clear alarm, "
+					"pending %d\n",
+					!!(alarm_pending & alarm_type_mask));
+				alarm_enabled &= ~alarm_type_mask;
+			}
+			spin_unlock_irqrestore(&alarm_slock, flags);
+			alarm_cancel(&alarms[i]);
+			spin_lock_irqsave(&alarm_slock, flags);
+		}
+		if (alarm_pending | wait_pending) {
+			if (alarm_pending)
+				pr_alarm(INFO, "alarm_release: clear "
+					"pending alarms %x\n", alarm_pending);
+			wake_unlock(&alarm_wake_lock);
+			wait_pending = 0;
+			alarm_pending = 0;
+		}
+		alarm_opened = 0;
+	}
+	spin_unlock_irqrestore(&alarm_slock, flags);
+	return 0;
+}
+
+static void alarm_triggered(struct alarm *alarm)
+{
+	unsigned long flags;
+	uint32_t alarm_type_mask = 1U << alarm->type;
+
+	pr_alarm(INT, "alarm_triggered type %d\n", alarm->type);
+	spin_lock_irqsave(&alarm_slock, flags);
+	if (alarm_enabled & alarm_type_mask) {
+		wake_lock_timeout(&alarm_wake_lock, 5 * HZ);
+		alarm_enabled &= ~alarm_type_mask;
+		alarm_pending |= alarm_type_mask;
+		wake_up(&alarm_wait_queue);
+	}
+	spin_unlock_irqrestore(&alarm_slock, flags);
+}
+
+static const struct file_operations alarm_fops = {
+	.owner = THIS_MODULE,
+	.unlocked_ioctl = alarm_ioctl,
+	.open = alarm_open,
+	.release = alarm_release,
+};
+
+static struct miscdevice alarm_device = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "alarm",
+	.fops = &alarm_fops,
+};
+
+static int __init alarm_dev_init(void)
+{
+	int err;
+	int i;
+
+	err = misc_register(&alarm_device);
+	if (err)
+		return err;
+
+	for (i = 0; i < ANDROID_ALARM_TYPE_COUNT; i++)
+		alarm_init(&alarms[i], i, alarm_triggered);
+	wake_lock_init(&alarm_wake_lock, WAKE_LOCK_SUSPEND, "alarm");
+
+	return 0;
+}
+
+static void  __exit alarm_dev_exit(void)
+{
+	misc_deregister(&alarm_device);
+	wake_lock_destroy(&alarm_wake_lock);
+}
+
+module_init(alarm_dev_init);
+module_exit(alarm_dev_exit);
+
diff --git a/drivers/staging/android/alarm.c b/drivers/staging/android/alarm.c
new file mode 100644
index 000000000000..c5bd51fd839f
--- /dev/null
+++ b/drivers/staging/android/alarm.c
@@ -0,0 +1,586 @@
+/* drivers/rtc/alarm.c
+ *
+ * Copyright (C) 2007-2009 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#include <asm/mach/time.h>
+#include <linux/device.h>
+#include <linux/miscdevice.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/sysdev.h>
+#include <linux/wakelock.h>
+#include "android_alarm.h"
+
+#define ANDROID_ALARM_PRINT_ERROR (1U << 0)
+#define ANDROID_ALARM_PRINT_INIT_STATUS (1U << 1)
+#define ANDROID_ALARM_PRINT_TSET (1U << 2)
+#define ANDROID_ALARM_PRINT_CALL (1U << 3)
+#define ANDROID_ALARM_PRINT_SUSPEND (1U << 4)
+#define ANDROID_ALARM_PRINT_INT (1U << 5)
+#define ANDROID_ALARM_PRINT_FLOW (1U << 6)
+
+static int debug_mask = ANDROID_ALARM_PRINT_ERROR | \
+			ANDROID_ALARM_PRINT_INIT_STATUS;
+module_param_named(debug_mask, debug_mask, int, S_IRUGO | S_IWUSR | S_IWGRP);
+
+#define pr_alarm(debug_level_mask, args...) \
+	do { \
+		if (debug_mask & ANDROID_ALARM_PRINT_##debug_level_mask) { \
+			pr_info(args); \
+		} \
+	} while (0)
+
+#define ANDROID_ALARM_WAKEUP_MASK ( \
+	ANDROID_ALARM_RTC_WAKEUP_MASK | \
+	ANDROID_ALARM_ELAPSED_REALTIME_WAKEUP_MASK)
+
+/* support old usespace code */
+#define ANDROID_ALARM_SET_OLD               _IOW('a', 2, time_t) /* set alarm */
+#define ANDROID_ALARM_SET_AND_WAIT_OLD      _IOW('a', 3, time_t)
+
+struct alarm_queue {
+	struct rb_root alarms;
+	struct rb_node *first;
+	struct hrtimer timer;
+	ktime_t delta;
+	bool stopped;
+	ktime_t stopped_time;
+};
+
+static struct rtc_device *alarm_rtc_dev;
+static DEFINE_SPINLOCK(alarm_slock);
+static DEFINE_MUTEX(alarm_setrtc_mutex);
+static struct wake_lock alarm_rtc_wake_lock;
+static struct platform_device *alarm_platform_dev;
+struct alarm_queue alarms[ANDROID_ALARM_TYPE_COUNT];
+static bool suspended;
+
+static void update_timer_locked(struct alarm_queue *base, bool head_removed)
+{
+	struct alarm *alarm;
+	bool is_wakeup = base == &alarms[ANDROID_ALARM_RTC_WAKEUP] ||
+			base == &alarms[ANDROID_ALARM_ELAPSED_REALTIME_WAKEUP];
+
+	if (base->stopped) {
+		pr_alarm(FLOW, "changed alarm while setting the wall time\n");
+		return;
+	}
+
+	if (is_wakeup && !suspended && head_removed)
+		wake_unlock(&alarm_rtc_wake_lock);
+
+	if (!base->first)
+		return;
+
+	alarm = container_of(base->first, struct alarm, node);
+
+	pr_alarm(FLOW, "selected alarm, type %d, func %pF at %lld\n",
+		alarm->type, alarm->function, ktime_to_ns(alarm->expires));
+
+	if (is_wakeup && suspended) {
+		pr_alarm(FLOW, "changed alarm while suspened\n");
+		wake_lock_timeout(&alarm_rtc_wake_lock, 1 * HZ);
+		return;
+	}
+
+	hrtimer_try_to_cancel(&base->timer);
+	base->timer.node.expires = ktime_add(base->delta, alarm->expires);
+	base->timer._softexpires = ktime_add(base->delta, alarm->softexpires);
+	hrtimer_start_expires(&base->timer, HRTIMER_MODE_ABS);
+}
+
+static void alarm_enqueue_locked(struct alarm *alarm)
+{
+	struct alarm_queue *base = &alarms[alarm->type];
+	struct rb_node **link = &base->alarms.rb_node;
+	struct rb_node *parent = NULL;
+	struct alarm *entry;
+	int leftmost = 1;
+
+	pr_alarm(FLOW, "added alarm, type %d, func %pF at %lld\n",
+		alarm->type, alarm->function, ktime_to_ns(alarm->expires));
+
+	if (base->first == &alarm->node)
+		base->first = rb_next(&alarm->node);
+	if (!RB_EMPTY_NODE(&alarm->node)) {
+		rb_erase(&alarm->node, &base->alarms);
+		RB_CLEAR_NODE(&alarm->node);
+	}
+
+	while (*link) {
+		parent = *link;
+		entry = rb_entry(parent, struct alarm, node);
+		/*
+		* We dont care about collisions. Nodes with
+		* the same expiry time stay together.
+		*/
+		if (alarm->expires.tv64 < entry->expires.tv64) {
+			link = &(*link)->rb_left;
+		} else {
+			link = &(*link)->rb_right;
+			leftmost = 0;
+		}
+	}
+	if (leftmost) {
+		base->first = &alarm->node;
+		update_timer_locked(base, false);
+	}
+
+	rb_link_node(&alarm->node, parent, link);
+	rb_insert_color(&alarm->node, &base->alarms);
+}
+
+/**
+ * alarm_init - initialize an alarm
+ * @alarm:	the alarm to be initialized
+ * @type:	the alarm type to be used
+ * @function:	alarm callback function
+ */
+void alarm_init(struct alarm *alarm,
+	enum android_alarm_type type, void (*function)(struct alarm *))
+{
+	RB_CLEAR_NODE(&alarm->node);
+	alarm->type = type;
+	alarm->function = function;
+
+	pr_alarm(FLOW, "created alarm, type %d, func %pF\n", type, function);
+}
+
+
+/**
+ * alarm_start_range - (re)start an alarm
+ * @alarm:	the alarm to be added
+ * @start:	earliest expiry time
+ * @end:	expiry time
+ */
+void alarm_start_range(struct alarm *alarm, ktime_t start, ktime_t end)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&alarm_slock, flags);
+	alarm->softexpires = start;
+	alarm->expires = end;
+	alarm_enqueue_locked(alarm);
+	spin_unlock_irqrestore(&alarm_slock, flags);
+}
+
+/**
+ * alarm_try_to_cancel - try to deactivate an alarm
+ * @alarm:	alarm to stop
+ *
+ * Returns:
+ *  0 when the alarm was not active
+ *  1 when the alarm was active
+ * -1 when the alarm may currently be excuting the callback function and
+ *    cannot be stopped (it may also be inactive)
+ */
+int alarm_try_to_cancel(struct alarm *alarm)
+{
+	struct alarm_queue *base = &alarms[alarm->type];
+	unsigned long flags;
+	bool first = false;
+	int ret = 0;
+
+	spin_lock_irqsave(&alarm_slock, flags);
+	if (!RB_EMPTY_NODE(&alarm->node)) {
+		pr_alarm(FLOW, "canceled alarm, type %d, func %pF at %lld\n",
+			alarm->type, alarm->function,
+			ktime_to_ns(alarm->expires));
+		ret = 1;
+		if (base->first == &alarm->node) {
+			base->first = rb_next(&alarm->node);
+			first = true;
+		}
+		rb_erase(&alarm->node, &base->alarms);
+		RB_CLEAR_NODE(&alarm->node);
+		if (first)
+			update_timer_locked(base, true);
+	} else
+		pr_alarm(FLOW, "tried to cancel alarm, type %d, func %pF\n",
+			alarm->type, alarm->function);
+	spin_unlock_irqrestore(&alarm_slock, flags);
+	if (!ret && hrtimer_callback_running(&base->timer))
+		ret = -1;
+	return ret;
+}
+
+/**
+ * alarm_cancel - cancel an alarm and wait for the handler to finish.
+ * @alarm:	the alarm to be cancelled
+ *
+ * Returns:
+ *  0 when the alarm was not active
+ *  1 when the alarm was active
+ */
+int alarm_cancel(struct alarm *alarm)
+{
+	for (;;) {
+		int ret = alarm_try_to_cancel(alarm);
+		if (ret >= 0)
+			return ret;
+		cpu_relax();
+	}
+}
+
+/**
+ * alarm_set_rtc - set the kernel and rtc walltime
+ * @new_time:	timespec value containing the new time
+ */
+int alarm_set_rtc(struct timespec new_time)
+{
+	int i;
+	int ret;
+	unsigned long flags;
+	struct rtc_time rtc_new_rtc_time;
+	struct timespec tmp_time;
+
+	rtc_time_to_tm(new_time.tv_sec, &rtc_new_rtc_time);
+
+	pr_alarm(TSET, "set rtc %ld %ld - rtc %02d:%02d:%02d %02d/%02d/%04d\n",
+		new_time.tv_sec, new_time.tv_nsec,
+		rtc_new_rtc_time.tm_hour, rtc_new_rtc_time.tm_min,
+		rtc_new_rtc_time.tm_sec, rtc_new_rtc_time.tm_mon + 1,
+		rtc_new_rtc_time.tm_mday,
+		rtc_new_rtc_time.tm_year + 1900);
+
+	mutex_lock(&alarm_setrtc_mutex);
+	spin_lock_irqsave(&alarm_slock, flags);
+	wake_lock(&alarm_rtc_wake_lock);
+	getnstimeofday(&tmp_time);
+	for (i = 0; i < ANDROID_ALARM_SYSTEMTIME; i++) {
+		hrtimer_try_to_cancel(&alarms[i].timer);
+		alarms[i].stopped = true;
+		alarms[i].stopped_time = timespec_to_ktime(tmp_time);
+	}
+	alarms[ANDROID_ALARM_ELAPSED_REALTIME_WAKEUP].delta =
+		alarms[ANDROID_ALARM_ELAPSED_REALTIME].delta =
+		ktime_sub(alarms[ANDROID_ALARM_ELAPSED_REALTIME].delta,
+			timespec_to_ktime(timespec_sub(tmp_time, new_time)));
+	spin_unlock_irqrestore(&alarm_slock, flags);
+	ret = do_settimeofday(&new_time);
+	spin_lock_irqsave(&alarm_slock, flags);
+	for (i = 0; i < ANDROID_ALARM_SYSTEMTIME; i++) {
+		alarms[i].stopped = false;
+		update_timer_locked(&alarms[i], false);
+	}
+	spin_unlock_irqrestore(&alarm_slock, flags);
+	if (ret < 0) {
+		pr_alarm(ERROR, "alarm_set_rtc: Failed to set time\n");
+		goto err;
+	}
+	if (!alarm_rtc_dev) {
+		pr_alarm(ERROR,
+			"alarm_set_rtc: no RTC, time will be lost on reboot\n");
+		goto err;
+	}
+	ret = rtc_set_time(alarm_rtc_dev, &rtc_new_rtc_time);
+	if (ret < 0)
+		pr_alarm(ERROR, "alarm_set_rtc: "
+			"Failed to set RTC, time will be lost on reboot\n");
+err:
+	wake_unlock(&alarm_rtc_wake_lock);
+	mutex_unlock(&alarm_setrtc_mutex);
+	return ret;
+}
+
+/**
+ * alarm_get_elapsed_realtime - get the elapsed real time in ktime_t format
+ *
+ * returns the time in ktime_t format
+ */
+ktime_t alarm_get_elapsed_realtime(void)
+{
+	ktime_t now;
+	unsigned long flags;
+	struct alarm_queue *base = &alarms[ANDROID_ALARM_ELAPSED_REALTIME];
+
+	spin_lock_irqsave(&alarm_slock, flags);
+	now = base->stopped ? base->stopped_time : ktime_get_real();
+	now = ktime_sub(now, base->delta);
+	spin_unlock_irqrestore(&alarm_slock, flags);
+	return now;
+}
+
+static enum hrtimer_restart alarm_timer_triggered(struct hrtimer *timer)
+{
+	struct alarm_queue *base;
+	struct alarm *alarm;
+	unsigned long flags;
+	ktime_t now;
+
+	spin_lock_irqsave(&alarm_slock, flags);
+
+	base = container_of(timer, struct alarm_queue, timer);
+	now = base->stopped ? base->stopped_time : hrtimer_cb_get_time(timer);
+	now = ktime_sub(now, base->delta);
+
+	pr_alarm(INT, "alarm_timer_triggered type %d at %lld\n",
+		base - alarms, ktime_to_ns(now));
+
+	while (base->first) {
+		alarm = container_of(base->first, struct alarm, node);
+		if (alarm->softexpires.tv64 > now.tv64) {
+			pr_alarm(FLOW, "don't call alarm, %pF, %lld (s %lld)\n",
+				alarm->function, ktime_to_ns(alarm->expires),
+				ktime_to_ns(alarm->softexpires));
+			break;
+		}
+		base->first = rb_next(&alarm->node);
+		rb_erase(&alarm->node, &base->alarms);
+		RB_CLEAR_NODE(&alarm->node);
+		pr_alarm(CALL, "call alarm, type %d, func %pF, %lld (s %lld)\n",
+			alarm->type, alarm->function,
+			ktime_to_ns(alarm->expires),
+			ktime_to_ns(alarm->softexpires));
+		spin_unlock_irqrestore(&alarm_slock, flags);
+		alarm->function(alarm);
+		spin_lock_irqsave(&alarm_slock, flags);
+	}
+	if (!base->first)
+		pr_alarm(FLOW, "no more alarms of type %d\n", base - alarms);
+	update_timer_locked(base, true);
+	spin_unlock_irqrestore(&alarm_slock, flags);
+	return HRTIMER_NORESTART;
+}
+
+static void alarm_triggered_func(void *p)
+{
+	struct rtc_device *rtc = alarm_rtc_dev;
+	if (!(rtc->irq_data & RTC_AF))
+		return;
+	pr_alarm(INT, "rtc alarm triggered\n");
+	wake_lock_timeout(&alarm_rtc_wake_lock, 1 * HZ);
+}
+
+static int alarm_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	int                 err = 0;
+	unsigned long       flags;
+	struct rtc_wkalrm   rtc_alarm;
+	struct rtc_time     rtc_current_rtc_time;
+	unsigned long       rtc_current_time;
+	unsigned long       rtc_alarm_time;
+	struct timespec     rtc_current_timespec;
+	struct timespec     rtc_delta;
+	struct alarm_queue *wakeup_queue = NULL;
+	struct alarm_queue *tmp_queue = NULL;
+
+	pr_alarm(SUSPEND, "alarm_suspend(%p, %d)\n", pdev, state.event);
+
+	spin_lock_irqsave(&alarm_slock, flags);
+	suspended = true;
+	spin_unlock_irqrestore(&alarm_slock, flags);
+
+	hrtimer_cancel(&alarms[ANDROID_ALARM_RTC_WAKEUP].timer);
+	hrtimer_cancel(&alarms[
+			ANDROID_ALARM_ELAPSED_REALTIME_WAKEUP_MASK].timer);
+
+	tmp_queue = &alarms[ANDROID_ALARM_RTC_WAKEUP];
+	if (tmp_queue->first)
+		wakeup_queue = tmp_queue;
+	tmp_queue = &alarms[ANDROID_ALARM_ELAPSED_REALTIME_WAKEUP];
+	if (tmp_queue->first && (!wakeup_queue ||
+				hrtimer_get_expires(&tmp_queue->timer).tv64 <
+				hrtimer_get_expires(&wakeup_queue->timer).tv64))
+		wakeup_queue = tmp_queue;
+	if (wakeup_queue) {
+		rtc_read_time(alarm_rtc_dev, &rtc_current_rtc_time);
+		rtc_current_timespec.tv_nsec = 0;
+		rtc_tm_to_time(&rtc_current_rtc_time,
+			       &rtc_current_timespec.tv_sec);
+		save_time_delta(&rtc_delta, &rtc_current_timespec);
+
+		rtc_alarm_time = timespec_sub(ktime_to_timespec(
+			hrtimer_get_expires(&wakeup_queue->timer)),
+			rtc_delta).tv_sec;
+
+		rtc_time_to_tm(rtc_alarm_time, &rtc_alarm.time);
+		rtc_alarm.enabled = 1;
+		rtc_set_alarm(alarm_rtc_dev, &rtc_alarm);
+		rtc_read_time(alarm_rtc_dev, &rtc_current_rtc_time);
+		rtc_tm_to_time(&rtc_current_rtc_time, &rtc_current_time);
+		pr_alarm(SUSPEND,
+			"rtc alarm set at %ld, now %ld, rtc delta %ld.%09ld\n",
+			rtc_alarm_time, rtc_current_time,
+			rtc_delta.tv_sec, rtc_delta.tv_nsec);
+		if (rtc_current_time + 1 >= rtc_alarm_time) {
+			pr_alarm(SUSPEND, "alarm about to go off\n");
+			memset(&rtc_alarm, 0, sizeof(rtc_alarm));
+			rtc_alarm.enabled = 0;
+			rtc_set_alarm(alarm_rtc_dev, &rtc_alarm);
+
+			spin_lock_irqsave(&alarm_slock, flags);
+			suspended = false;
+			wake_lock_timeout(&alarm_rtc_wake_lock, 2 * HZ);
+			update_timer_locked(&alarms[ANDROID_ALARM_RTC_WAKEUP],
+									false);
+			update_timer_locked(&alarms[
+				ANDROID_ALARM_ELAPSED_REALTIME_WAKEUP], false);
+			err = -EBUSY;
+			spin_unlock_irqrestore(&alarm_slock, flags);
+		}
+	}
+	return err;
+}
+
+static int alarm_resume(struct platform_device *pdev)
+{
+	struct rtc_wkalrm alarm;
+	unsigned long       flags;
+
+	pr_alarm(SUSPEND, "alarm_resume(%p)\n", pdev);
+
+	memset(&alarm, 0, sizeof(alarm));
+	alarm.enabled = 0;
+	rtc_set_alarm(alarm_rtc_dev, &alarm);
+
+	spin_lock_irqsave(&alarm_slock, flags);
+	suspended = false;
+	update_timer_locked(&alarms[ANDROID_ALARM_RTC_WAKEUP], false);
+	update_timer_locked(&alarms[ANDROID_ALARM_ELAPSED_REALTIME_WAKEUP],
+									false);
+	spin_unlock_irqrestore(&alarm_slock, flags);
+
+	return 0;
+}
+
+static struct rtc_task alarm_rtc_task = {
+	.func = alarm_triggered_func
+};
+
+static int rtc_alarm_add_device(struct device *dev,
+				struct class_interface *class_intf)
+{
+	int err;
+	struct rtc_device *rtc = to_rtc_device(dev);
+
+	mutex_lock(&alarm_setrtc_mutex);
+
+	if (alarm_rtc_dev) {
+		err = -EBUSY;
+		goto err1;
+	}
+
+	alarm_platform_dev =
+		platform_device_register_simple("alarm", -1, NULL, 0);
+	if (IS_ERR(alarm_platform_dev)) {
+		err = PTR_ERR(alarm_platform_dev);
+		goto err2;
+	}
+	err = rtc_irq_register(rtc, &alarm_rtc_task);
+	if (err)
+		goto err3;
+	alarm_rtc_dev = rtc;
+	pr_alarm(INIT_STATUS, "using rtc device, %s, for alarms", rtc->name);
+	mutex_unlock(&alarm_setrtc_mutex);
+
+	return 0;
+
+err3:
+	platform_device_unregister(alarm_platform_dev);
+err2:
+err1:
+	mutex_unlock(&alarm_setrtc_mutex);
+	return err;
+}
+
+static void rtc_alarm_remove_device(struct device *dev,
+				    struct class_interface *class_intf)
+{
+	if (dev == &alarm_rtc_dev->dev) {
+		pr_alarm(INIT_STATUS, "lost rtc device for alarms");
+		rtc_irq_unregister(alarm_rtc_dev, &alarm_rtc_task);
+		platform_device_unregister(alarm_platform_dev);
+		alarm_rtc_dev = NULL;
+	}
+}
+
+static struct class_interface rtc_alarm_interface = {
+	.add_dev = &rtc_alarm_add_device,
+	.remove_dev = &rtc_alarm_remove_device,
+};
+
+static struct platform_driver alarm_driver = {
+	.suspend = alarm_suspend,
+	.resume = alarm_resume,
+	.driver = {
+		.name = "alarm"
+	}
+};
+
+static int __init alarm_late_init(void)
+{
+	unsigned long   flags;
+	struct timespec tmp_time, system_time;
+
+	/* this needs to run after the rtc is read at boot */
+	spin_lock_irqsave(&alarm_slock, flags);
+	/* We read the current rtc and system time so we can later calulate
+	 * elasped realtime to be (boot_systemtime + rtc - boot_rtc) ==
+	 * (rtc - (boot_rtc - boot_systemtime))
+	 */
+	getnstimeofday(&tmp_time);
+	ktime_get_ts(&system_time);
+	alarms[ANDROID_ALARM_ELAPSED_REALTIME_WAKEUP].delta =
+		alarms[ANDROID_ALARM_ELAPSED_REALTIME].delta =
+			timespec_to_ktime(timespec_sub(tmp_time, system_time));
+
+	spin_unlock_irqrestore(&alarm_slock, flags);
+	return 0;
+}
+
+static int __init alarm_driver_init(void)
+{
+	int err;
+	int i;
+
+	for (i = 0; i < ANDROID_ALARM_SYSTEMTIME; i++) {
+		hrtimer_init(&alarms[i].timer,
+				CLOCK_REALTIME, HRTIMER_MODE_ABS);
+		alarms[i].timer.function = alarm_timer_triggered;
+	}
+	hrtimer_init(&alarms[ANDROID_ALARM_SYSTEMTIME].timer,
+		     CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
+	alarms[ANDROID_ALARM_SYSTEMTIME].timer.function = alarm_timer_triggered;
+	err = platform_driver_register(&alarm_driver);
+	if (err < 0)
+		goto err1;
+	wake_lock_init(&alarm_rtc_wake_lock, WAKE_LOCK_SUSPEND, "alarm_rtc");
+	rtc_alarm_interface.class = rtc_class;
+	err = class_interface_register(&rtc_alarm_interface);
+	if (err < 0)
+		goto err2;
+
+	return 0;
+
+err2:
+	wake_lock_destroy(&alarm_rtc_wake_lock);
+	platform_driver_unregister(&alarm_driver);
+err1:
+	return err;
+}
+
+static void  __exit alarm_exit(void)
+{
+	class_interface_unregister(&rtc_alarm_interface);
+	wake_lock_destroy(&alarm_rtc_wake_lock);
+	platform_driver_unregister(&alarm_driver);
+}
+
+late_initcall(alarm_late_init);
+module_init(alarm_driver_init);
+module_exit(alarm_exit);
+
diff --git a/drivers/staging/android/android_alarm.h b/drivers/staging/android/android_alarm.h
new file mode 100644
index 000000000000..753ed93bc4d3
--- /dev/null
+++ b/drivers/staging/android/android_alarm.h
@@ -0,0 +1,106 @@
+/* include/linux/android_alarm.h
+ *
+ * Copyright (C) 2006-2007 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */
+
+#ifndef _LINUX_ANDROID_ALARM_H
+#define _LINUX_ANDROID_ALARM_H
+
+#include <linux/ioctl.h>
+#include <linux/time.h>
+
+enum android_alarm_type {
+	/* return code bit numbers or set alarm arg */
+	ANDROID_ALARM_RTC_WAKEUP,
+	ANDROID_ALARM_RTC,
+	ANDROID_ALARM_ELAPSED_REALTIME_WAKEUP,
+	ANDROID_ALARM_ELAPSED_REALTIME,
+	ANDROID_ALARM_SYSTEMTIME,
+
+	ANDROID_ALARM_TYPE_COUNT,
+
+	/* return code bit numbers */
+	/* ANDROID_ALARM_TIME_CHANGE = 16 */
+};
+
+#ifdef __KERNEL__
+
+#include <linux/ktime.h>
+#include <linux/rbtree.h>
+
+/*
+ * The alarm interface is similar to the hrtimer interface but adds support
+ * for wakeup from suspend. It also adds an elapsed realtime clock that can
+ * be used for periodic timers that need to keep runing while the system is
+ * suspended and not be disrupted when the wall time is set.
+ */
+
+/**
+ * struct alarm - the basic alarm structure
+ * @node:	red black tree node for time ordered insertion
+ * @type:	alarm type. rtc/elapsed-realtime/systemtime, wakeup/non-wakeup.
+ * @softexpires: the absolute earliest expiry time of the alarm.
+ * @expires:	the absolute expiry time.
+ * @function:	alarm expiry callback function
+ *
+ * The alarm structure must be initialized by alarm_init()
+ *
+ */
+
+struct alarm {
+	struct rb_node		node;
+	enum android_alarm_type type;
+	ktime_t			softexpires;
+	ktime_t			expires;
+	void			(*function)(struct alarm *);
+};
+
+void alarm_init(struct alarm *alarm,
+	enum android_alarm_type type, void (*function)(struct alarm *));
+void alarm_start_range(struct alarm *alarm, ktime_t start, ktime_t end);
+int alarm_try_to_cancel(struct alarm *alarm);
+int alarm_cancel(struct alarm *alarm);
+ktime_t alarm_get_elapsed_realtime(void);
+
+/* set rtc while preserving elapsed realtime */
+int alarm_set_rtc(const struct timespec ts);
+
+#endif
+
+enum android_alarm_return_flags {
+	ANDROID_ALARM_RTC_WAKEUP_MASK = 1U << ANDROID_ALARM_RTC_WAKEUP,
+	ANDROID_ALARM_RTC_MASK = 1U << ANDROID_ALARM_RTC,
+	ANDROID_ALARM_ELAPSED_REALTIME_WAKEUP_MASK =
+				1U << ANDROID_ALARM_ELAPSED_REALTIME_WAKEUP,
+	ANDROID_ALARM_ELAPSED_REALTIME_MASK =
+				1U << ANDROID_ALARM_ELAPSED_REALTIME,
+	ANDROID_ALARM_SYSTEMTIME_MASK = 1U << ANDROID_ALARM_SYSTEMTIME,
+	ANDROID_ALARM_TIME_CHANGE_MASK = 1U << 16
+};
+
+/* Disable alarm */
+#define ANDROID_ALARM_CLEAR(type)           _IO('a', 0 | ((type) << 4))
+
+/* Ack last alarm and wait for next */
+#define ANDROID_ALARM_WAIT                  _IO('a', 1)
+
+#define ALARM_IOW(c, type, size)            _IOW('a', (c) | ((type) << 4), size)
+/* Set alarm */
+#define ANDROID_ALARM_SET(type)             ALARM_IOW(2, type, struct timespec)
+#define ANDROID_ALARM_SET_AND_WAIT(type)    ALARM_IOW(3, type, struct timespec)
+#define ANDROID_ALARM_GET_TIME(type)        ALARM_IOW(4, type, struct timespec)
+#define ANDROID_ALARM_SET_RTC               _IOW('a', 5, struct timespec)
+#define ANDROID_ALARM_BASE_CMD(cmd)         (cmd & ~(_IOC(0, 0, 0xf0, 0)))
+#define ANDROID_ALARM_IOCTL_TO_TYPE(cmd)    (_IOC_NR(cmd) >> 4)
+
+#endif