From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 arch/arm/include/asm/mcs_spinlock.h | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)
 create mode 100644 arch/arm/include/asm/mcs_spinlock.h

(limited to 'arch/arm/include/asm/mcs_spinlock.h')

diff --git a/arch/arm/include/asm/mcs_spinlock.h b/arch/arm/include/asm/mcs_spinlock.h
new file mode 100644
index 000000000..f652ad658
--- /dev/null
+++ b/arch/arm/include/asm/mcs_spinlock.h
@@ -0,0 +1,23 @@
+#ifndef __ASM_MCS_LOCK_H
+#define __ASM_MCS_LOCK_H
+
+#ifdef CONFIG_SMP
+#include <asm/spinlock.h>
+
+/* MCS spin-locking. */
+#define arch_mcs_spin_lock_contended(lock)				\
+do {									\
+	/* Ensure prior stores are observed before we enter wfe. */	\
+	smp_mb();							\
+	while (!(smp_load_acquire(lock)))				\
+		wfe();							\
+} while (0)								\
+
+#define arch_mcs_spin_unlock_contended(lock)				\
+do {									\
+	smp_store_release(lock, 1);					\
+	dsb_sev();							\
+} while (0)
+
+#endif	/* CONFIG_SMP */
+#endif	/* __ASM_MCS_LOCK_H */
-- 
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