PM: Add user-space wake lock api.

This adds /sys/power/wake_lock and /sys/power/wake_unlock.
Writing a string to wake_lock creates a wake lock the
first time is sees a string and locks it. Optionally, the
string can be followed by a timeout.
To unlock the wake lock, write the same string to wake_unlock.

Change-Id: I66c6e3fe6487d17f9c2fafde1174042e57d15cd7

5 files changed, 250 insertions, 0 deletions

diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
index 4916349285b..aa728bc65ae 100644
--- a/kernel/power/Kconfig
+++ b/kernel/power/Kconfig
@@ -37,6 +37,16 @@ config WAKELOCK_STAT
 	---help---
 	  Report wake lock stats in /proc/wakelocks
 
+config USER_WAKELOCK
+	bool "Userspace wake locks"
+	depends on WAKELOCK
+	default y
+	---help---
+	  User-space wake lock api. Write "lockname" or "lockname timeout"
+	  to /sys/power/wake_lock lock and if needed create a wake lock.
+	  Write "lockname" to /sys/power/wake_unlock to unlock a user wake
+	  lock.
+
 config HIBERNATE_CALLBACKS
 	bool
 
diff --git a/kernel/power/Makefile b/kernel/power/Makefile
index 0f41f20311c..58eb0aac0b3 100644
--- a/kernel/power/Makefile
+++ b/kernel/power/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_PM_TEST_SUSPEND)	+= suspend_test.o
 obj-$(CONFIG_HIBERNATION)	+= hibernate.o snapshot.o swap.o user.o \
 				   block_io.o
 obj-$(CONFIG_WAKELOCK)		+= wakelock.o
+obj-$(CONFIG_USER_WAKELOCK)	+= userwakelock.o
 obj-$(CONFIG_SUSPEND_TIME)	+= suspend_time.o
 
 obj-$(CONFIG_MAGIC_SYSRQ)	+= poweroff.o
diff --git a/kernel/power/main.c b/kernel/power/main.c
index 9824b41e5a1..1edafb23ee9 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -402,6 +402,11 @@ power_attr(pm_trace_dev_match);
 
 #endif /* CONFIG_PM_TRACE */
 
+#ifdef CONFIG_USER_WAKELOCK
+power_attr(wake_lock);
+power_attr(wake_unlock);
+#endif
+
 static struct attribute * g[] = {
 	&state_attr.attr,
 #ifdef CONFIG_PM_TRACE
@@ -414,6 +419,10 @@ static struct attribute * g[] = {
 #ifdef CONFIG_PM_DEBUG
 	&pm_test_attr.attr,
 #endif
+#ifdef CONFIG_USER_WAKELOCK
+	&wake_lock_attr.attr,
+	&wake_unlock_attr.attr,
+#endif
 #endif
 	NULL,
 };
diff --git a/kernel/power/power.h b/kernel/power/power.h
index fcf91e3d181..a16bcef540a 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -276,3 +276,14 @@ extern struct workqueue_struct *suspend_work_queue;
 extern struct wake_lock main_wake_lock;
 extern suspend_state_t requested_suspend_state;
 #endif
+
+#ifdef CONFIG_USER_WAKELOCK
+ssize_t wake_lock_show(struct kobject *kobj, struct kobj_attribute *attr,
+			char *buf);
+ssize_t wake_lock_store(struct kobject *kobj, struct kobj_attribute *attr,
+			const char *buf, size_t n);
+ssize_t wake_unlock_show(struct kobject *kobj, struct kobj_attribute *attr,
+			char *buf);
+ssize_t  wake_unlock_store(struct kobject *kobj, struct kobj_attribute *attr,
+			const char *buf, size_t n);
+#endif
diff --git a/kernel/power/userwakelock.c b/kernel/power/userwakelock.c
new file mode 100644
index 00000000000..a28a8db4146
--- /dev/null
+++ b/kernel/power/userwakelock.c
@@ -0,0 +1,219 @@
+/* kernel/power/userwakelock.c
+ *
+ * Copyright (C) 2005-2008 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 <linux/ctype.h>
+#include <linux/module.h>
+#include <linux/wakelock.h>
+#include <linux/slab.h>
+
+#include "power.h"
+
+enum {
+	DEBUG_FAILURE	= BIT(0),
+	DEBUG_ERROR	= BIT(1),
+	DEBUG_NEW	= BIT(2),
+	DEBUG_ACCESS	= BIT(3),
+	DEBUG_LOOKUP	= BIT(4),
+};
+static int debug_mask = DEBUG_FAILURE;
+module_param_named(debug_mask, debug_mask, int, S_IRUGO | S_IWUSR | S_IWGRP);
+
+static DEFINE_MUTEX(tree_lock);
+
+struct user_wake_lock {
+	struct rb_node		node;
+	struct wake_lock	wake_lock;
+	char			name[0];
+};
+struct rb_root user_wake_locks;
+
+static struct user_wake_lock *lookup_wake_lock_name(
+	const char *buf, int allocate, long *timeoutptr)
+{
+	struct rb_node **p = &user_wake_locks.rb_node;
+	struct rb_node *parent = NULL;
+	struct user_wake_lock *l;
+	int diff;
+	u64 timeout;
+	int name_len;
+	const char *arg;
+
+	/* Find length of lock name and start of optional timeout string */
+	arg = buf;
+	while (*arg && !isspace(*arg))
+		arg++;
+	name_len = arg - buf;
+	if (!name_len)
+		goto bad_arg;
+	while (isspace(*arg))
+		arg++;
+
+	/* Process timeout string */
+	if (timeoutptr && *arg) {
+		timeout = simple_strtoull(arg, (char **)&arg, 0);
+		while (isspace(*arg))
+			arg++;
+		if (*arg)
+			goto bad_arg;
+		/* convert timeout from nanoseconds to jiffies > 0 */
+		timeout += (NSEC_PER_SEC / HZ) - 1;
+		do_div(timeout, (NSEC_PER_SEC / HZ));
+		if (timeout <= 0)
+			timeout = 1;
+		*timeoutptr = timeout;
+	} else if (*arg)
+		goto bad_arg;
+	else if (timeoutptr)
+		*timeoutptr = 0;
+
+	/* Lookup wake lock in rbtree */
+	while (*p) {
+		parent = *p;
+		l = rb_entry(parent, struct user_wake_lock, node);
+		diff = strncmp(buf, l->name, name_len);
+		if (!diff && l->name[name_len])
+			diff = -1;
+		if (debug_mask & DEBUG_ERROR)
+			pr_info("lookup_wake_lock_name: compare %.*s %s %d\n",
+				name_len, buf, l->name, diff);
+
+		if (diff < 0)
+			p = &(*p)->rb_left;
+		else if (diff > 0)
+			p = &(*p)->rb_right;
+		else
+			return l;
+	}
+
+	/* Allocate and add new wakelock to rbtree */
+	if (!allocate) {
+		if (debug_mask & DEBUG_ERROR)
+			pr_info("lookup_wake_lock_name: %.*s not found\n",
+				name_len, buf);
+		return ERR_PTR(-EINVAL);
+	}
+	l = kzalloc(sizeof(*l) + name_len + 1, GFP_KERNEL);
+	if (l == NULL) {
+		if (debug_mask & DEBUG_FAILURE)
+			pr_err("lookup_wake_lock_name: failed to allocate "
+				"memory for %.*s\n", name_len, buf);
+		return ERR_PTR(-ENOMEM);
+	}
+	memcpy(l->name, buf, name_len);
+	if (debug_mask & DEBUG_NEW)
+		pr_info("lookup_wake_lock_name: new wake lock %s\n", l->name);
+	wake_lock_init(&l->wake_lock, WAKE_LOCK_SUSPEND, l->name);
+	rb_link_node(&l->node, parent, p);
+	rb_insert_color(&l->node, &user_wake_locks);
+	return l;
+
+bad_arg:
+	if (debug_mask & DEBUG_ERROR)
+		pr_info("lookup_wake_lock_name: wake lock, %.*s, bad arg, %s\n",
+			name_len, buf, arg);
+	return ERR_PTR(-EINVAL);
+}
+
+ssize_t wake_lock_show(
+	struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+	char *s = buf;
+	char *end = buf + PAGE_SIZE;
+	struct rb_node *n;
+	struct user_wake_lock *l;
+
+	mutex_lock(&tree_lock);
+
+	for (n = rb_first(&user_wake_locks); n != NULL; n = rb_next(n)) {
+		l = rb_entry(n, struct user_wake_lock, node);
+		if (wake_lock_active(&l->wake_lock))
+			s += scnprintf(s, end - s, "%s ", l->name);
+	}
+	s += scnprintf(s, end - s, "\n");
+
+	mutex_unlock(&tree_lock);
+	return (s - buf);
+}
+
+ssize_t wake_lock_store(
+	struct kobject *kobj, struct kobj_attribute *attr,
+	const char *buf, size_t n)
+{
+	long timeout;
+	struct user_wake_lock *l;
+
+	mutex_lock(&tree_lock);
+	l = lookup_wake_lock_name(buf, 1, &timeout);
+	if (IS_ERR(l)) {
+		n = PTR_ERR(l);
+		goto bad_name;
+	}
+
+	if (debug_mask & DEBUG_ACCESS)
+		pr_info("wake_lock_store: %s, timeout %ld\n", l->name, timeout);
+
+	if (timeout)
+		wake_lock_timeout(&l->wake_lock, timeout);
+	else
+		wake_lock(&l->wake_lock);
+bad_name:
+	mutex_unlock(&tree_lock);
+	return n;
+}
+
+
+ssize_t wake_unlock_show(
+	struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+{
+	char *s = buf;
+	char *end = buf + PAGE_SIZE;
+	struct rb_node *n;
+	struct user_wake_lock *l;
+
+	mutex_lock(&tree_lock);
+
+	for (n = rb_first(&user_wake_locks); n != NULL; n = rb_next(n)) {
+		l = rb_entry(n, struct user_wake_lock, node);
+		if (!wake_lock_active(&l->wake_lock))
+			s += scnprintf(s, end - s, "%s ", l->name);
+	}
+	s += scnprintf(s, end - s, "\n");
+
+	mutex_unlock(&tree_lock);
+	return (s - buf);
+}
+
+ssize_t wake_unlock_store(
+	struct kobject *kobj, struct kobj_attribute *attr,
+	const char *buf, size_t n)
+{
+	struct user_wake_lock *l;
+
+	mutex_lock(&tree_lock);
+	l = lookup_wake_lock_name(buf, 0, NULL);
+	if (IS_ERR(l)) {
+		n = PTR_ERR(l);
+		goto not_found;
+	}
+
+	if (debug_mask & DEBUG_ACCESS)
+		pr_info("wake_unlock_store: %s\n", l->name);
+
+	wake_unlock(&l->wake_lock);
+not_found:
+	mutex_unlock(&tree_lock);
+	return n;
+}
+