1 files changed, 53 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/atomic.h b/arch/riscv/include/asm/atomic.h
new file mode 100644
index 00000000..b79e1f89
--- /dev/null
+++ b/arch/riscv/include/asm/atomic.h
@@ -0,0 +1,53 @@
+#ifndef _ASM_RISCV_ATOMIC_H
+#define _ASM_RISCV_ATOMIC_H
+
+#include <linux/types.h>
+#include <asm/barrier.h>
+
+typedef struct {
+	volatile long counter;
+} atomic_t;
+
+#define ATOMIC_INIT(_lptr, val) (_lptr)->counter = (val)
+
+#define ATOMIC_INITIALIZER(val)   \
+	{                         \
+		.counter = (val), \
+	}
+
+long atomic_read(atomic_t *atom)
+{
+	long ret = atom->counter;
+	rmb();
+	return ret;
+}
+
+void atomic_write(atomic_t *atom, long value)
+{
+	atom->counter = value;
+	wmb();
+}
+
+long atomic_add_return(atomic_t *atom, long value)
+{
+	long ret;
+#if __SIZEOF_LONG__ == 4
+	__asm__ __volatile__("	amoadd.w.aqrl  %1, %2, %0"
+			     : "+A"(atom->counter), "=r"(ret)
+			     : "r"(value)
+			     : "memory");
+#elif __SIZEOF_LONG__ == 8
+	__asm__ __volatile__("	amoadd.d.aqrl  %1, %2, %0"
+			     : "+A"(atom->counter), "=r"(ret)
+			     : "r"(value)
+			     : "memory");
+#endif
+	return ret + value;
+}
+
+long atomic_sub_return(atomic_t *atom, long value)
+{
+	return atomic_add_return(atom, -value);
+}
+
+#endif /* _ASM_RISCV_ATOMIC_H */