1 files changed, 85 insertions, 0 deletions
diff --git a/arch/metag/include/asm/barrier.h b/arch/metag/include/asm/barrier.h
new file mode 100644
index 00000000000..c90bfc6bf64
--- /dev/null
+++ b/arch/metag/include/asm/barrier.h
@@ -0,0 +1,85 @@
+#ifndef _ASM_METAG_BARRIER_H
+#define _ASM_METAG_BARRIER_H
+
+#include <asm/metag_mem.h>
+
+#define nop()		asm volatile ("NOP")
+#define mb()		wmb()
+#define rmb()		barrier()
+
+#ifdef CONFIG_METAG_META21
+
+/* HTP and above have a system event to fence writes */
+static inline void wr_fence(void)
+{
+	volatile int *flushptr = (volatile int *) LINSYSEVENT_WR_FENCE;
+	barrier();
+	*flushptr = 0;
+}
+
+#else /* CONFIG_METAG_META21 */
+
+/*
+ * ATP doesn't have system event to fence writes, so it is necessary to flush
+ * the processor write queues as well as possibly the write combiner (depending
+ * on the page being written).
+ * To ensure the write queues are flushed we do 4 writes to a system event
+ * register (in this case write combiner flush) which will also flush the write
+ * combiner.
+ */
+static inline void wr_fence(void)
+{
+	volatile int *flushptr = (volatile int *) LINSYSEVENT_WR_COMBINE_FLUSH;
+	barrier();
+	*flushptr = 0;
+	*flushptr = 0;
+	*flushptr = 0;
+	*flushptr = 0;
+}
+
+#endif /* !CONFIG_METAG_META21 */
+
+static inline void wmb(void)
+{
+	/* flush writes through the write combiner */
+	wr_fence();
+}
+
+#define read_barrier_depends()  do { } while (0)
+
+#ifndef CONFIG_SMP
+#define fence()		do { } while (0)
+#define smp_mb()        barrier()
+#define smp_rmb()       barrier()
+#define smp_wmb()       barrier()
+#else
+
+#ifdef CONFIG_METAG_SMP_WRITE_REORDERING
+/*
+ * Write to the atomic memory unlock system event register (command 0). This is
+ * needed before a write to shared memory in a critical section, to prevent
+ * external reordering of writes before the fence on other threads with writes
+ * after the fence on this thread (and to prevent the ensuing cache-memory
+ * incoherence). It is therefore ineffective if used after and on the same
+ * thread as a write.
+ */
+static inline void fence(void)
+{
+	volatile int *flushptr = (volatile int *) LINSYSEVENT_WR_ATOMIC_UNLOCK;
+	barrier();
+	*flushptr = 0;
+}
+#define smp_mb()        fence()
+#define smp_rmb()       fence()
+#define smp_wmb()       barrier()
+#else
+#define fence()		do { } while (0)
+#define smp_mb()        barrier()
+#define smp_rmb()       barrier()
+#define smp_wmb()       barrier()
+#endif
+#endif
+#define smp_read_barrier_depends()     do { } while (0)
+#define set_mb(var, value) do { var = value; smp_mb(); } while (0)
+
+#endif /* _ASM_METAG_BARRIER_H */