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[v6,13/17] arm: Add spinlock implementation

Message ID 1405066787-5793-14-git-send-email-drjones@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Andrew Jones July 11, 2014, 8:19 a.m. UTC 
From: Christoffer Dall <christoffer.dall@linaro.org>

Add simple busy-wait spinlock implementation for ARM.

Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Andrew Jones <drjones@redhat.com>
---
 config/config-arm.mak  |  3 ++-
 lib/arm/asm/spinlock.h |  9 ++-------
 lib/arm/spinlock.c     | 28 ++++++++++++++++++++++++++++
 3 files changed, 32 insertions(+), 8 deletions(-)
 create mode 100644 lib/arm/spinlock.c
diff mbox

Patch

diff --git a/config/config-arm.mak b/config/config-arm.mak
index 3225018faf933..fb160b6c65e2a 100644
--- a/config/config-arm.mak
+++ b/config/config-arm.mak
@@ -36,7 +36,8 @@  cflatobjs += \
 	lib/virtio.o \
 	lib/chr-testdev.o \
 	lib/arm/io.o \
-	lib/arm/setup.o
+	lib/arm/setup.o \
+	lib/arm/spinlock.o
 
 libeabi = lib/arm/libeabi.a
 eabiobjs = lib/arm/eabi_compat.o
diff --git a/lib/arm/asm/spinlock.h b/lib/arm/asm/spinlock.h
index 04f5a1a5538e2..2118a4b3751e0 100644
--- a/lib/arm/asm/spinlock.h
+++ b/lib/arm/asm/spinlock.h
@@ -5,12 +5,7 @@  struct spinlock {
 	int v;
 };
 
-//TODO
-static inline void spin_lock(struct spinlock *lock __unused)
-{
-}
-static inline void spin_unlock(struct spinlock *lock __unused)
-{
-}
+extern void spin_lock(struct spinlock *lock);
+extern void spin_unlock(struct spinlock *lock);
 
 #endif /* _ASMARM_SPINLOCK_H_ */
diff --git a/lib/arm/spinlock.c b/lib/arm/spinlock.c
new file mode 100644
index 0000000000000..d8a6d4c3383d6
--- /dev/null
+++ b/lib/arm/spinlock.c
@@ -0,0 +1,28 @@ 
+#include "libcflat.h"
+#include "asm/spinlock.h"
+#include "asm/barrier.h"
+
+void spin_lock(struct spinlock *lock)
+{
+	u32 val, fail;
+
+	dmb();
+	do {
+		asm volatile(
+		"1:	ldrex	%0, [%2]\n"
+		"	teq	%0, #0\n"
+		"	bne	1b\n"
+		"	mov	%0, #1\n"
+		"	strex	%1, %0, [%2]\n"
+		: "=&r" (val), "=&r" (fail)
+		: "r" (&lock->v)
+		: "cc" );
+	} while (fail);
+	dmb();
+}
+
+void spin_unlock(struct spinlock *lock)
+{
+	lock->v = 0;
+	dmb();
+}