LoongArch: Add atomic/locking headers

Add common headers (atomic, bitops, barrier and locking) for basic
LoongArch support.

Reviewed-by: WANG Xuerui <git@xen0n.name>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

1 files changed, 51 insertions, 0 deletions

diff --git a/arch/loongarch/include/asm/barrier.h b/arch/loongarch/include/asm/barrier.h
new file mode 100644
index 000000000000..e57571bcaf4f
--- /dev/null
+++ b/arch/loongarch/include/asm/barrier.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+#ifndef __ASM_BARRIER_H
+#define __ASM_BARRIER_H
+
+#define __sync()	__asm__ __volatile__("dbar 0" : : : "memory")
+
+#define fast_wmb()	__sync()
+#define fast_rmb()	__sync()
+#define fast_mb()	__sync()
+#define fast_iob()	__sync()
+#define wbflush()	__sync()
+
+#define wmb()		fast_wmb()
+#define rmb()		fast_rmb()
+#define mb()		fast_mb()
+#define iob()		fast_iob()
+
+/**
+ * array_index_mask_nospec() - generate a ~0 mask when index < size, 0 otherwise
+ * @index: array element index
+ * @size: number of elements in array
+ *
+ * Returns:
+ *     0 - (@index < @size)
+ */
+#define array_index_mask_nospec array_index_mask_nospec
+static inline unsigned long array_index_mask_nospec(unsigned long index,
+						    unsigned long size)
+{
+	unsigned long mask;
+
+	__asm__ __volatile__(
+		"sltu	%0, %1, %2\n\t"
+#if (__SIZEOF_LONG__ == 4)
+		"sub.w	%0, $r0, %0\n\t"
+#elif (__SIZEOF_LONG__ == 8)
+		"sub.d	%0, $r0, %0\n\t"
+#endif
+		: "=r" (mask)
+		: "r" (index), "r" (size)
+		:);
+
+	return mask;
+}
+
+#include <asm-generic/barrier.h>
+
+#endif /* __ASM_BARRIER_H */