[PATCH 07/13] PM: wakelock: Add /sys/power/request_state

["Arve Hjønnevåg" <arve@android.com>]

This is a non-blocking interface that specifies which suspend state to
enter when no wakelocks are locked. A special state, "on", stops the
process by locking the "main" wakelock.

If early-suspend support is enabled, early suspend handlers will be called
when a state other than "on" is written. When writing "on", the corresonding
resume handlers are called.

Signed-off-by: Arve Hjønnevåg <arve@android.com>
---
 kernel/power/main.c |   74 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 74 insertions(+), 0 deletions(-)

diff --git a/kernel/power/main.c b/kernel/power/main.c
index e2aae3e..676a8b0 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -22,6 +22,7 @@
 #include <linux/freezer.h>
 #include <linux/vmstat.h>
 #include <linux/syscalls.h>
+#include <linux/wakelock.h>
 
 #include "power.h"
 
@@ -388,6 +389,9 @@ static void suspend_finish(void)
 
 
 static const char * const pm_states[PM_SUSPEND_MAX] = {
+#ifdef CONFIG_WAKELOCK
+	[PM_SUSPEND_ON]		= "on",
+#endif
 	[PM_SUSPEND_STANDBY]	= "standby",
 	[PM_SUSPEND_MEM]	= "mem",
 };
@@ -545,6 +549,73 @@ static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr,
 power_attr(state);
 #endif
 
+/**
+ *	request_state - control system power state.
+ *
+ *	This is similar to state, but it does not block until the system
+ *	resumes, and it will try to re-enter the state until another state is
+ *	requsted. Wakelocks are respected and the requested state will only
+ *	be entered when no wakelocks are held. Write "on" to cancel.
+ *
+ *	If CONFIG_EARLYSUSPEND is set, early_suspend hooks are called when
+ *	the requested state changes to or from "on"
+ */
+
+#ifdef CONFIG_WAKELOCK
+static ssize_t request_state_show(struct kobject *kobj, struct kobj_attribute *attr,
+			  char *buf)
+{
+	char *s = buf;
+	int i;
+
+	for (i = 0; i < PM_SUSPEND_MAX; i++) {
+		if (pm_states[i] && valid_state(i))
+			s += sprintf(s,"%s ", pm_states[i]);
+	}
+	if (s != buf)
+		/* convert the last space to a newline */
+		*(s-1) = '\n';
+	return (s - buf);
+}
+
+static ssize_t request_state_store(struct kobject *kobj, struct kobj_attribute *attr,
+			   const char *buf, size_t n)
+{
+	suspend_state_t state = PM_SUSPEND_ON;
+	const char * const *s;
+	char *p;
+	int len;
+	int error = -EINVAL;
+
+	p = memchr(buf, '\n', n);
+	len = p ? p - buf : n;
+
+	for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
+		if (*s && len == strlen(*s) && !strncmp(buf, *s, len))
+			break;
+	}
+	if (state < PM_SUSPEND_MAX && *s)
+		if (state == PM_SUSPEND_ON || valid_state(state)) {
+			error = 0;
+#ifdef CONFIG_EARLYSUSPEND
+			request_suspend_state(state);
+#else
+			if (!mutex_trylock(&pm_mutex))
+				return -EBUSY;
+			requested_suspend_state = state;
+			if (state == PM_SUSPEND_ON)
+				wake_lock(&main_wake_lock);
+			else
+				wake_unlock(&main_wake_lock);
+			mutex_unlock(&pm_mutex);
+#endif
+		}
+	return error ? error : n;
+}
+
+power_attr(request_state);
+#endif
+
 #ifdef CONFIG_PM_TRACE
 int pm_trace_enabled;
 
@@ -574,6 +645,9 @@ static struct attribute * g[] = {
 #ifndef CONFIG_DISABLE_SYS_POWER_STATE
 	&state_attr.attr,
 #endif
+#ifdef CONFIG_WAKELOCK
+	&request_state_attr.attr,
+#endif
 #ifdef CONFIG_PM_TRACE
 	&pm_trace_attr.attr,
 #endif
-- 
1.6.1

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