ARM: 8287/1: 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>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 21 insertions, 0 deletions

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 97d07ed60a0b..c3a986d45125 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -29,6 +29,7 @@ config ARM
         select HANDLE_DOMAIN_IRQ
         select HARDIRQS_SW_RESEND
         select HAVE_ARCH_AUDITSYSCALL if (AEABI && !OABI_COMPAT)
+        select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
         select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL
         select HAVE_ARCH_KGDB
         select HAVE_ARCH_SECCOMP_FILTER if (AEABI && !OABI_COMPAT)
diff --git a/arch/arm/include/asm/bitrev.h b/arch/arm/include/asm/bitrev.h
new file mode 100644
index 000000000000..ec291c350ea3
--- /dev/null
+++ b/arch/arm/include/asm/bitrev.h
@@ -0,0 +1,20 @@
+#ifndef __ASM_BITREV_H
+#define __ASM_BITREV_H
+
+static __always_inline __attribute_const__ u32 __arch_bitrev32(u32 x)
+{
+        __asm__ ("rbit %0, %1" : "=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