[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>

1 files changed, 4 insertions, 1 deletions

diff --git a/kernel/power/main.c b/kernel/power/main.c
index 22bdc93cc038..18d7d693fbba 100644
--- a/kernel/power/main.c
+++ b/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");