Android PM driver. It is utilize linux wakeup_source and also provide early suspend like implementation.

android-pm.patch

diff --git a/drivers/staging/android/Kconfig b/drivers/staging/android/Kconfig
index 05f1105..b18990a 100644
--- a/drivers/staging/android/Kconfig
+++ b/drivers/staging/android/Kconfig
@@ -81,6 +81,13 @@ config ANDROID_INTF_ALARM_DEV
 	  elapsed realtime, and a non-wakeup alarm on the monotonic clock.
 	  Also exports the alarm interface to user-space.
 
+config ANDROID_PM
+	bool "Android PM support"
+	depends on PM && PM_SLEEP
+	default n
+	help
+	  Enable the Android PM support.
+
 endif # if ANDROID
 
 endmenu
diff --git a/drivers/staging/android/Makefile b/drivers/staging/android/Makefile
index 848164a..377a0f6 100644
--- a/drivers/staging/android/Makefile
+++ b/drivers/staging/android/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_ANDROID_TIMED_GPIO)	+= timed_gpio.o
 obj-$(CONFIG_ANDROID_LOW_MEMORY_KILLER)	+= lowmemorykiller.o
 obj-$(CONFIG_ANDROID_SWITCH)		+= switch/
 obj-$(CONFIG_ANDROID_INTF_ALARM_DEV)	+= alarm-dev.o
+obj-$(CONFIG_ANDROID_PM)		+= android_pm.o
 obj-$(CONFIG_PERSISTENT_TRACER)		+= trace_persistent.o
 
 CFLAGS_REMOVE_trace_persistent.o = -pg
diff --git a/drivers/staging/android/android_pm.c b/drivers/staging/android/android_pm.c
new file mode 100644
index 0000000..bd23383
--- /dev/null
+++ b/drivers/staging/android/android_pm.c
@@ -0,0 +1,536 @@
+/*
+ * Android PM driver
+ * 
+ * Copyright (c) 2012 Suryandaru Triandana <syndtr@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/fs.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+#include <linux/atomic.h>
+#include <linux/list.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/workqueue.h>
+#include <linux/kobject.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+#include <linux/suspend.h>
+#include <linux/platform_device.h>
+#include <linux/jiffies.h>
+
+#include "android_pm.h"
+
+enum {
+	STATE_RESUMED	= 1,
+	STATE_RESUMING,
+	STATE_SUSPENDING,
+	STATE_SUSPENDED
+};
+
+static struct android_pm {
+	struct device *dev;
+	struct kobject *kobj;
+	struct wakeup_source *ws;
+	struct mutex mutex_pm;
+	struct mutex mutex_ws;
+	atomic_t state;
+	struct workqueue_struct *wq;
+	struct work_struct work;
+	struct workqueue_struct *suspend_wq;
+	struct work_struct suspend_work;
+	wait_queue_head_t wait;
+	wait_queue_head_t wait_event;
+	atomic_t wait_event_pending;
+	struct list_head devices;
+	struct list_head suspend_head;
+	struct list_head resume_head;
+	struct rb_root user_ws;
+} android_pm_state;
+
+struct android_pm_dev {
+	struct device *dev;
+	const struct android_pm_ops *ops;
+	struct list_head list;
+	struct list_head work_list;
+};
+
+struct android_pm_user_ws {
+	char *name;
+	struct rb_node node;
+	struct wakeup_source *ws;
+};
+
+static struct android_pm_user_ws *user_ws_lookup(struct android_pm *pm,
+						 const char *name)
+{
+	struct rb_root *root = &(pm->user_ws);
+	struct rb_node **new = &(root->rb_node), *parent = NULL;
+	struct android_pm_user_ws *ws;
+	int result;
+
+	mutex_lock(&pm->mutex_ws);
+	
+	/* Figure out where to put new node */
+	while (*new) {
+		ws = container_of(*new, struct android_pm_user_ws, node);
+		result = strcmp(name, ws->name + 2);
+
+		parent = *new;
+		if (result < 0)
+			new = &((*new)->rb_left);
+		else if (result > 0)
+			new = &((*new)->rb_right);
+		else
+			goto end;
+	}
+
+	ws = kmalloc(sizeof(struct android_pm_user_ws) + strlen(name) + 3,
+		     GFP_KERNEL);
+	if (!ws)
+		goto end;
+
+	ws->name = ((char *)ws + sizeof(struct android_pm_user_ws));
+	sprintf(ws->name, "u/%s", name);
+	ws->ws = wakeup_source_register(ws->name);
+	if (!ws->ws) {
+		kfree(ws);
+		ws = NULL;
+		goto end;
+	}
+
+	/* Add new node and rebalance tree. */
+	rb_init_node(&ws->node);
+	rb_link_node(&ws->node, parent, new);
+	rb_insert_color(&ws->node, root);
+
+end:
+	mutex_unlock(&pm->mutex_ws);
+	return ws;
+}
+
+static void user_ws_free(struct android_pm *pm, struct android_pm_user_ws *ws)
+{
+	mutex_lock(&pm->mutex_ws);
+	wakeup_source_unregister(ws->ws);
+	rb_erase(&ws->node, &pm->user_ws);
+	kfree(ws);
+	mutex_unlock(&pm->mutex_ws);
+}
+
+static void android_pm_schedule(struct android_pm *pm)
+{
+	__pm_stay_awake(pm->ws);
+	queue_work(pm->wq, &pm->work);
+}
+
+int android_pm_enable(struct device *dev, const struct android_pm_ops *ops)
+{
+	struct android_pm *pm = &android_pm_state;
+	struct android_pm_dev *d;
+	int ret = 0;
+	
+	if (!dev)
+		return -EINVAL;
+
+	mutex_lock(&pm->mutex_pm);
+
+	list_for_each_entry(d, &pm->devices, list) {
+		if (d->dev == dev)
+			goto done;
+	}
+
+	d = kmalloc(sizeof(struct android_pm_dev), GFP_KERNEL);
+	if (d == NULL) {
+		ret = -ENOMEM;
+		goto done;
+	}
+
+	d->dev = dev;
+	d->ops = ops;
+
+	list_add(&d->list, &pm->devices);
+	list_add(&d->work_list, &pm->suspend_head);
+	if (atomic_cmpxchg(&pm->state, STATE_SUSPENDED, STATE_SUSPENDING) == STATE_SUSPENDED)
+		android_pm_schedule(pm);
+
+done:
+	mutex_unlock(&pm->mutex_pm);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(android_pm_enable);
+
+int android_pm_disable(struct device *dev)
+{
+	struct android_pm *pm = &android_pm_state;
+	struct android_pm_dev *d;
+	int ret = -ENODEV;
+
+	mutex_lock(&pm->mutex_pm);
+
+	list_for_each_entry(d, &pm->devices, list) {
+		if (d->dev == dev) {
+			list_del(&d->list);
+			list_del(&d->work_list);
+			kfree(d);
+			ret = 0;
+			goto done;
+		}
+	}
+
+done:
+	mutex_unlock(&pm->mutex_pm);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(android_pm_disable);
+
+static void do_one_suspend(struct android_pm *pm,
+			   struct android_pm_dev *d)
+{
+	int ret;
+	if (d->ops && d->ops->suspend) {
+		ret = d->ops->suspend(d->dev);
+		if (ret < 0)
+			pr_warn("android_pm: failed to suspend '%s' ret=%d\n",
+			       dev_name(d->dev), ret);
+	}
+	list_move(&d->work_list, &pm->resume_head);
+}
+
+static void do_one_resume(struct android_pm *pm,
+			   struct android_pm_dev *d)
+{
+	int ret;
+	if (d->ops && d->ops->resume) {
+		ret = d->ops->resume(d->dev);
+		if (ret < 0)
+			pr_warn("android_pm: failed to resume '%s' ret=%d\n",
+			       dev_name(d->dev), ret);
+	}
+	list_move(&d->work_list, &pm->suspend_head);
+}
+
+static void android_pm_work(struct work_struct *work)
+{
+	struct android_pm *pm = &android_pm_state;
+	struct android_pm_dev *d;
+	int state;
+	
+	wait_event(pm->wait_event, !atomic_read(&pm->wait_event_pending));
+
+	mutex_lock(&pm->mutex_pm);
+	while (1) {
+		if ((state = atomic_read(&pm->state)) == STATE_SUSPENDING) {
+			if (list_empty(&pm->suspend_head)) {
+				if (atomic_cmpxchg(&pm->state, STATE_SUSPENDING, STATE_SUSPENDED) == STATE_SUSPENDING)
+					break;
+				else
+					continue;
+			}
+
+			d = list_first_entry(&pm->suspend_head, struct android_pm_dev, work_list);
+			do_one_suspend(pm, d);
+		} else if (state == STATE_RESUMING) {
+			if (list_empty(&pm->resume_head)) {
+				if (atomic_cmpxchg(&pm->state, STATE_RESUMING, STATE_RESUMED) == STATE_RESUMING) {
+					wake_up(&pm->wait);
+					break;
+				} else
+					continue;
+			}
+
+			d = list_first_entry(&pm->resume_head, struct android_pm_dev, work_list);
+			do_one_resume(pm, d);
+		} else
+			break;
+	}
+	mutex_unlock(&pm->mutex_pm);
+
+	__pm_relax(pm->ws);
+	queue_work(pm->suspend_wq, &pm->suspend_work);
+}
+
+static void pm_suspend_work(struct work_struct *work)
+{
+	struct android_pm *pm = &android_pm_state;
+	unsigned int count;
+	int ret;
+
+	if (atomic_read(&pm->state) != STATE_SUSPENDED)
+		return;
+
+	ret = pm_get_wakeup_count(&count);
+	if (atomic_read(&pm->state) == STATE_SUSPENDED) {
+		if (ret) {
+			pm_save_wakeup_count(count);
+			pm_suspend(PM_SUSPEND_MEM);
+		} else
+			queue_work(pm->suspend_wq, &pm->suspend_work);
+	}
+}
+
+static ssize_t android_pm_state_show(struct kobject *kobj,
+				     struct kobj_attribute *attr,
+				     char *buf)
+{
+	struct android_pm *pm = &android_pm_state;
+	const char *state_str = "unknown";
+
+	switch (atomic_read(&pm->state)) {
+	case STATE_RESUMED:
+		state_str = "resumed";
+		break;
+	case STATE_RESUMING:
+		state_str = "resuming";
+		break;
+	case STATE_SUSPENDED:
+		state_str = "suspended";
+		break;
+	case STATE_SUSPENDING:
+		state_str = "suspending";
+		break;
+	default:
+		break;
+	}
+
+	return sprintf(buf, "%s\n", state_str);
+}
+
+static ssize_t android_pm_state_store(struct kobject *kobj,
+				      struct kobj_attribute *attr,
+				      const char *buf, size_t count)
+{
+	struct android_pm *pm = &android_pm_state;
+
+	if (count < 1)
+		return -EINVAL;
+
+	switch (*buf) {
+	case 'r':
+		if (atomic_cmpxchg(&pm->state, STATE_SUSPENDED, STATE_RESUMING) == STATE_SUSPENDED)
+			android_pm_schedule(pm);
+		else
+			atomic_cmpxchg(&pm->state, STATE_SUSPENDING, STATE_RESUMING);
+		break;
+	case 's':
+		if (atomic_cmpxchg(&pm->state, STATE_RESUMED, STATE_SUSPENDING) == STATE_RESUMED) {
+			wake_up(&pm->wait);
+			android_pm_schedule(pm);
+		} else
+			atomic_cmpxchg(&pm->state, STATE_RESUMING, STATE_SUSPENDING);
+		break;
+	default:
+		pr_err("android_pm: unknown state '%c'\n", *buf);
+		return -EINVAL;
+	}
+
+	return count;
+}
+
+static ssize_t android_pm_wait(struct kobject *kobj,
+			       struct kobj_attribute *attr,
+			       const char *buf, size_t count)
+{
+	struct android_pm *pm = &android_pm_state;
+	int state, ret = 0;
+
+	if (count < 1)
+		return -EINVAL;
+
+	switch (*buf) {
+	case 'r':
+		if (atomic_cmpxchg(&pm->wait_event_pending, 1, 0))
+			wake_up(&pm->wait_event);
+		ret = wait_event_interruptible(pm->wait,
+			(atomic_read(&pm->state) == STATE_RESUMED));
+		break;
+	case 's':
+		atomic_set(&pm->wait_event_pending, 1);
+		ret = wait_event_interruptible(pm->wait,
+			((state = atomic_read(&pm->state)) == STATE_SUSPENDING ||
+			 state == STATE_SUSPENDED));
+		break;
+	default:
+		pr_err("android_pm: unknown wait type '%c'\n", *buf);
+		return -EINVAL;
+	}
+
+	return ((ret < 0) ? ret : count);
+}
+
+static ssize_t android_pm_wakeup_ref(struct kobject *kobj,
+				     struct kobj_attribute *attr,
+				     const char *buf, size_t count)
+{
+	struct android_pm *pm = &android_pm_state;
+	struct android_pm_user_ws *ws;
+
+	if (count == 0 || !buf)
+		return -EINVAL;
+
+	ws = user_ws_lookup(pm, buf);
+	if (!ws)
+		return -ENOMEM;
+
+	__pm_stay_awake(ws->ws);
+
+	return count;
+}
+
+static ssize_t android_pm_wakeup_unref(struct kobject *kobj,
+				       struct kobj_attribute *attr,
+				       const char *buf, size_t count)
+{
+	struct android_pm *pm = &android_pm_state;
+	struct android_pm_user_ws *ws;
+	
+	if (count == 0 || !buf)
+		return -EINVAL;
+
+	ws = user_ws_lookup(pm, buf);
+	if (!ws)
+		return -ENOMEM;
+
+	__pm_relax(ws->ws);
+
+	return count;
+}
+
+static struct kobj_attribute state_attribute =
+	__ATTR(state, 0666, android_pm_state_show, android_pm_state_store);
+static struct kobj_attribute wait_attribute =
+	__ATTR(wait, 0666, NULL, android_pm_wait);
+static struct kobj_attribute wakeup_ref_attribute =
+	__ATTR(wakeup_ref, 0666, NULL, android_pm_wakeup_ref);
+static struct kobj_attribute wakeup_unref_attribute =
+	__ATTR(wakeup_unref, 0666, NULL, android_pm_wakeup_unref);
+
+static struct attribute *attrs[] = {
+	&state_attribute.attr,
+	&wait_attribute.attr,
+	&wakeup_ref_attribute.attr,
+	&wakeup_unref_attribute.attr,
+	NULL,
+};
+
+static struct attribute_group attr_group = {
+	.attrs = attrs,
+};
+
+static int __devinit android_pm_probe(struct platform_device *pdev)
+{
+	struct android_pm *pm = &android_pm_state;
+	int ret;
+
+	pm->kobj = kobject_create_and_add("android_pm", power_kobj);
+	if (!pm->kobj)
+		return -ENOMEM;
+
+	ret = sysfs_create_group(pm->kobj, &attr_group);
+	if (ret)
+		goto err;
+	
+	pm->ws = wakeup_source_register("android_pm");
+	if (!pm->ws) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	pm->wq = create_singlethread_workqueue("android_pm");
+	if (!pm->wq) {
+		ret = -ENOMEM;
+		goto err_ws;
+	}
+
+	pm->suspend_wq = create_singlethread_workqueue("android_pm_suspend");
+	if (!pm->suspend_wq) {
+		ret = -ENOMEM;
+		goto err_wq;
+	}
+
+	mutex_init(&pm->mutex_pm);
+	mutex_init(&pm->mutex_ws);
+	atomic_set(&pm->state, STATE_RESUMED);
+	INIT_LIST_HEAD(&pm->devices);
+	INIT_LIST_HEAD(&pm->suspend_head);
+	INIT_LIST_HEAD(&pm->resume_head);
+	INIT_WORK(&pm->work, android_pm_work);
+	INIT_WORK(&pm->suspend_work, pm_suspend_work);
+	init_waitqueue_head(&pm->wait);
+	init_waitqueue_head(&pm->wait_event);
+	atomic_set(&pm->wait_event_pending, 0);
+
+	dev_set_drvdata(&pdev->dev, pm);
+
+	return 0;
+
+err_wq:
+	destroy_workqueue(pm->wq);
+err_ws:
+	wakeup_source_unregister(pm->ws);
+err:
+	kobject_put(pm->kobj);
+	return ret;
+}
+
+static void android_pm_complete(struct device *dev)
+{
+	struct android_pm *pm = &android_pm_state;
+
+	__pm_wakeup_event(pm->ws, 200);
+	queue_work(pm->suspend_wq, &pm->suspend_work);
+}
+
+static const struct dev_pm_ops android_pm_ops = {
+	.complete	= android_pm_complete,
+};
+
+struct platform_driver android_pm_driver = {
+	.probe	= android_pm_probe,
+	.driver = {
+		.name	= "android_pm",
+		.pm	= &android_pm_ops,
+		.suppress_bind_attrs	= true,
+	},
+};
+
+struct platform_device android_pm_pdev = {
+	.name	= "android_pm",
+};
+
+static int __init android_pm_init(void)
+{
+	int ret;
+
+	ret = platform_device_register(&android_pm_pdev);
+	if (ret)
+		return ret;
+
+	ret = platform_driver_register(&android_pm_driver);
+	if (ret) {
+		platform_device_unregister(&android_pm_pdev);
+		return ret;
+	}
+
+	return 0;
+}
+postcore_initcall(android_pm_init);
diff --git a/drivers/staging/android/android_pm.h b/drivers/staging/android/android_pm.h
new file mode 100644
index 0000000..a7d4163
--- /dev/null
+++ b/drivers/staging/android/android_pm.h
@@ -0,0 +1,46 @@
+
+#ifndef _ANDROID_PM_H
+#define _ANDROID_PM_H
+
+#ifdef CONFIG_ANDROID_PM
+
+struct android_pm_ops {
+	int (*suspend)(struct device *dev);
+	int (*resume)(struct device *dev);
+};
+
+#define SET_ANDROID_PM_SLEEP_OPS(suspend_fn, resume_fn) \
+	.suspend = suspend_fn, \
+	.resume = resume_fn,
+
+#define ANDROID_PM_OPS(name, suspend_fn, resume_fn) \
+const struct android_pm_ops name = { \
+	SET_ANDROID_PM_SLEEP_OPS(suspend_fn, resume_fn) \
+}
+#define STATIC_ANDROID_PM_OPS(name, suspend_fn, resume_fn) \
+	static ANDROID_PM_OPS(name, suspend_fn, resume_fn)
+
+#define ANDROID_PM_OPS_PROTO(name) \
+	const struct android_pm_ops name
+#define STATIC_ANDROID_PM_OPS_PROTO(name) \
+	static ANDROID_PM_OPS_PROTO(name)
+
+extern int android_pm_enable(struct device *dev, const struct android_pm_ops *ops);
+extern int android_pm_disable(struct device *dev);
+
+#else
+
+#define SET_ANDROID_PM_SLEEP_OPS(suspend_fn, resume_fn)
+
+#define ANDROID_PM_OPS(name, suspend_fn, resume_fn)
+#define STATIC_ANDROID_PM_OPS(name, suspend_fn, resume_fn)
+
+#define ANDROID_PM_OPS_PROTO(name)
+#define STATIC_ANDROID_PM_OPS_PROTO(name)
+
+static inline int android_pm_enable(struct device *dev, const struct android_pm_ops *ops) { return 0; }
+static inline int android_pm_disable(struct device *dev) { return 0; }
+
+#endif
+
+#endif // _ANDROID_PM_H
\ No newline at end of file

Have you made updates to this? How has it worked out for you?