ARM: tegra: cpuidle: Make abort_flag atomic

Replace memory accessors with atomic API just to make code consistent
with the abort_barrier. The new variant may be even more correct now
since atomic_read() will prevent compiler from generating wrong things
like carrying abort_flag value in a register instead of re-fetching it
from memory.
Acked-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Tested-by: Peter Geis <pgwipeout@gmail.com>
Tested-by: Jasper Korten <jja2000@gmail.com>
Tested-by: David Heidelberg <david@ixit.cz>
Tested-by: Nicolas Chauvet <kwizart@gmail.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

arch/arm/mach-tegra/cpuidle-tegra20.c

@@ -32,7 +32,7 @@
 #include "sleep.h"
 
 #ifdef CONFIG_PM_SLEEP
-static bool abort_flag;
+static atomic_t abort_flag;
 static atomic_t abort_barrier;
 static int tegra20_idle_lp2_coupled(struct cpuidle_device *dev,
 				    struct cpuidle_driver *drv,
@@ -171,13 +171,14 @@ static int tegra20_idle_lp2_coupled(struct cpuidle_device *dev,
 	bool entered_lp2 = false;
 
 	if (tegra_pending_sgi())
-		WRITE_ONCE(abort_flag, true);
+		atomic_set(&abort_flag, 1);
 
 	cpuidle_coupled_parallel_barrier(dev, &abort_barrier);
 
-	if (abort_flag) {
+	if (atomic_read(&abort_flag)) {
 		cpuidle_coupled_parallel_barrier(dev, &abort_barrier);
-		abort_flag = false;	/* clean flag for next coming */
+		/* clean flag for next coming */
+		atomic_set(&abort_flag, 0);
 		return -EINTR;
 	}