openrisc: add optimized atomic operations

Using the l.lwa and l.swa atomic instruction pair.
Most openrisc processor cores provide these instructions now. If the
instructions are not available emulation is provided.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
[shorne@gmail.com: remove OPENRISC_HAVE_INST_LWA_SWA config suggesed by
Alan Cox https://lkml.org/lkml/2014/7/23/666]
[shorne@gmail.com: expand to implement all ops suggested by Peter
Zijlstra https://lkml.org/lkml/2017/2/20/317]
Signed-off-by: Stafford Horne <shorne@gmail.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h
index 9ed8b987185b..3f38eb03649c 100644
--- a/include/asm-generic/atomic.h
+++ b/include/asm-generic/atomic.h
@@ -223,6 +223,7 @@ static inline void atomic_dec(atomic_t *v)
 #define atomic_xchg(ptr, v)             (xchg(&(ptr)->counter, (v)))
 #define atomic_cmpxchg(v, old, new)     (cmpxchg(&((v)->counter), (old), (new)))
 
+#ifndef __atomic_add_unless
 static inline int __atomic_add_unless(atomic_t *v, int a, int u)
 {
         int c, old;
@@ -231,5 +232,6 @@ static inline int __atomic_add_unless(atomic_t *v, int a, int u)
                 c = old;
         return c;
 }
+#endif
 
 #endif /* __ASM_GENERIC_ATOMIC_H */