[Sound-open-firmware] [PATCH] locks: Add try_lock API to attempt lock access without spinning

[Liam Girdwood]

Add a try version to acquire a spin lock.

Signed-off-by: Liam Girdwood <liam.r.girdwood at linux.intel.com>
---
 src/arch/xtensa/include/arch/spinlock.h | 18 ++++++++++++++++++
 src/include/reef/lock.h                 |  4 ++++
 2 files changed, 22 insertions(+)

diff --git a/src/arch/xtensa/include/arch/spinlock.h b/src/arch/xtensa/include/arch/spinlock.h
index acb1b8e..13bf4c1 100644
--- a/src/arch/xtensa/include/arch/spinlock.h
+++ b/src/arch/xtensa/include/arch/spinlock.h
@@ -62,6 +62,24 @@ static inline void arch_spin_lock(spinlock_t *lock)
 		: "memory");
 }
 
+static inline int arch_try_lock(spinlock_t *lock)
+{
+	uint32_t result;
+
+	__asm__ __volatile__(
+		"       movi    %0, 0\n"
+		"       wsr     %0, scompare1\n"
+		"       movi    %0, 1\n"
+		"       s32c1i  %0, %1, 0\n"
+		: "=&a" (result)
+		: "a" (&lock->lock)
+		: "memory");
+
+	if (result)
+		return 0; /* lock failed */
+	return 1; /* lock acquired */
+}
+
 static inline void arch_spin_unlock(spinlock_t *lock)
 {
 	uint32_t result;
diff --git a/src/include/reef/lock.h b/src/include/reef/lock.h
index eef2a3a..deb0fb7 100644
--- a/src/include/reef/lock.h
+++ b/src/include/reef/lock.h
@@ -149,6 +149,10 @@ extern uint32_t lock_dbg_user[DBG_LOCK_USERS];
 	spin_lock_dbg(); \
 	arch_spin_lock(lock);
 
+#define spin_try_lock(lock) \
+	spin_lock_dbg(); \
+	arch_try_lock(lock);
+
 #define spin_unlock(lock) \
 	arch_spin_unlock(lock); \
 	spin_unlock_dbg();
-- 
2.14.1