MIPS: TXx9: Microoptimize interrupt handlers

The IOC interrupt status register on RBTX49XX only have 8 bits.  Use
8-bit version of __fls() to optimize interrupt handlers.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 18 insertions, 0 deletions

diff --git a/include/asm-mips/txx9/generic.h b/include/asm-mips/txx9/generic.h
index 1e1a9f2d2379..dc85515eac13 100644
--- a/include/asm-mips/txx9/generic.h
+++ b/include/asm-mips/txx9/generic.h
@@ -64,4 +64,22 @@ struct physmap_flash_data;
 void txx9_physmap_flash_init(int no, unsigned long addr, unsigned long size,
                              const struct physmap_flash_data *pdata);
 
+/* 8 bit version of __fls(): find first bit set (returns 0..7) */
+static inline unsigned int __fls8(unsigned char x)
+{
+        int r = 7;
+
+        if (!(x & 0xf0)) {
+                r -= 4;
+                x <<= 4;
+        }
+        if (!(x & 0xc0)) {
+                r -= 2;
+                x <<= 2;
+        }
+        if (!(x & 0x80))
+                r -= 1;
+        return r;
+}
+
 #endif /* __ASM_TXX9_GENERIC_H */