ARM: 8189/1: arm64:add bitrev.h file to support rbit instruction

This patch add bitrev.h file to support rbit instruction,
so that we can do bitrev operation by hardware.

Signed-off-by: Yalin Wang <yalin.wang@sonymobile.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 20 insertions, 0 deletions

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index b1f9a20a3677..0ed36d1f536d 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -39,6 +39,7 @@ config ARM64
         select HARDIRQS_SW_RESEND
         select HAVE_ALIGNED_STRUCT_PAGE if SLUB
         select HAVE_ARCH_AUDITSYSCALL
+        select HAVE_ARCH_BITREVERSE
         select HAVE_ARCH_JUMP_LABEL
         select HAVE_ARCH_KGDB
         select HAVE_ARCH_SECCOMP_FILTER
diff --git a/arch/arm64/include/asm/bitrev.h b/arch/arm64/include/asm/bitrev.h
new file mode 100644
index 000000000000..a5a0c3660137
--- /dev/null
+++ b/arch/arm64/include/asm/bitrev.h
@@ -0,0 +1,19 @@
+#ifndef __ASM_BITREV_H
+#define __ASM_BITREV_H
+static __always_inline __attribute_const__ u32 __arch_bitrev32(u32 x)
+{
+        __asm__ ("rbit %w0, %w1" : "=r" (x) : "r" (x));
+        return x;
+}
+
+static __always_inline __attribute_const__ u16 __arch_bitrev16(u16 x)
+{
+        return __arch_bitrev32((u32)x) >> 16;
+}
+
+static __always_inline __attribute_const__ u8 __arch_bitrev8(u8 x)
+{
+        return __arch_bitrev32((u32)x) >> 24;
+}
+
+#endif