ARM: Implement atomic_swap_int(9). It's used in DRM2 code.

Approved by:	kib (mentor)

3 files changed, 27 insertions, 0 deletions

diff --git a/sys/arm/include/atomic-v4.h b/sys/arm/include/atomic-v4.h
index e8f6fb2..0c0b377 100644
--- a/sys/arm/include/atomic-v4.h
+++ b/sys/arm/include/atomic-v4.h
@@ -363,6 +363,13 @@ atomic_readandclear_32(volatile u_int32_t *p)
 	return (__swp(0, p));
 }
 
+static __inline uint32_t
+atomic_swap_32(volatile u_int32_t *p, u_int32_t v)
+{
+
+	return (__swp(v, p));
+}
+
 #define atomic_cmpset_rel_32	atomic_cmpset_32
 #define atomic_cmpset_acq_32	atomic_cmpset_32
 #define atomic_set_rel_32	atomic_set_32
diff --git a/sys/arm/include/atomic-v6.h b/sys/arm/include/atomic-v6.h
index aa1780f..06cb507 100644
--- a/sys/arm/include/atomic-v6.h
+++ b/sys/arm/include/atomic-v6.h
@@ -641,6 +641,25 @@ atomic_testandset_64(volatile uint64_t *p, u_int v)
 	return (atomic_testandset_32(p32, v));
 }
 
+static __inline uint32_t
+atomic_swap_32(volatile uint32_t *p, uint32_t v)
+{
+	uint32_t ret, exflag;
+
+	__asm __volatile(
+	    "1: ldrex	%[ret], [%[ptr]]		\n"
+	    "   strex	%[exf], %[val], [%[ptr]]	\n"
+	    "   teq	%[exf], #0			\n"
+	    "   it	ne				\n"
+	    "   bne	1b				\n"
+	    : [ret] "=r"  (ret),
+	      [exf] "=&r" (exflag)
+	    : [val] "r"  (v),
+	      [ptr] "r"  (p)
+	    : "cc", "memory");
+	return (ret);
+}
+
 #undef ATOMIC_ACQ_REL
 #undef ATOMIC_ACQ_REL_LONG
 
diff --git a/sys/arm/include/atomic.h b/sys/arm/include/atomic.h
index 039af34..ee89f06 100644
--- a/sys/arm/include/atomic.h
+++ b/sys/arm/include/atomic.h
@@ -109,5 +109,6 @@ atomic_store_long(volatile u_long *dst, u_long src)
 #define atomic_readandclear_int		atomic_readandclear_32
 #define atomic_load_acq_int		atomic_load_acq_32
 #define atomic_store_rel_int		atomic_store_rel_32
+#define atomic_swap_int			atomic_swap_32
 
 #endif /* _MACHINE_ATOMIC_H_ */