[PATCH] introduce .valid callback for pm_ops

Add pm_ops.valid callback, so only the available pm states show in
/sys/power/state.  And this also makes an earlier states error report at
enter_state before we do actual suspend/resume.

Signed-off-by: Shaohua Li<shaohua.li@intel.com>
Acked-by: Pavel Machek<pavel@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

drivers/acpi/sleep/main.c

@@ -158,7 +158,15 @@ int acpi_suspend(u32 acpi_state)
 	return -EINVAL;
 }
 
+static int acpi_pm_state_valid(suspend_state_t pm_state)
+{
+	u32 acpi_state = acpi_suspend_states[pm_state];
+
+	return sleep_states[acpi_state];
+}
+
 static struct pm_ops acpi_pm_ops = {
+	.valid = acpi_pm_state_valid,
 	.prepare = acpi_pm_prepare,
 	.enter = acpi_pm_enter,
 	.finish = acpi_pm_finish,

include/linux/pm.h

@@ -170,6 +170,7 @@ typedef int __bitwise suspend_disk_method_t;
 
 struct pm_ops {
 	suspend_disk_method_t pm_disk_mode;
+	int (*valid)(suspend_state_t state);
 	int (*prepare)(suspend_state_t state);
 	int (*enter)(suspend_state_t state);
 	int (*finish)(suspend_state_t state);

kernel/power/main.c

@@ -167,6 +167,8 @@ static int enter_state(suspend_state_t state)
 {
 	int error;
 
+	if (pm_ops->valid && !pm_ops->valid(state))
+		return -ENODEV;
 	if (down_trylock(&pm_sem))
 		return -EBUSY;
 
@@ -236,7 +238,8 @@ static ssize_t state_show(struct subsystem * subsys, char * buf)
 	char * s = buf;
 
 	for (i = 0; i < PM_SUSPEND_MAX; i++) {
-		if (pm_states[i])
+		if (pm_states[i] && pm_ops && (!pm_ops->valid
+			||(pm_ops->valid && pm_ops->valid(i))))
 			s += sprintf(s,"%s ",pm_states[i]);
 	}
 	s += sprintf(s,"\n");