m68k: Unroll raw_outsb() loop

Unroll the raw_outsb() loop using the optimized assembler code from
raw_outsw(). That code is copied and pasted, with movew changed to moveb.

This improves the performance of sequential write transfers using mac_esp
in PIO mode by 5% or 10%. (The DMA controller on the 840av/660av models is
still unsupported so PIO transfers are used.)

Tested-by: Stan Johnson <userm57@yahoo.com>
Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

diff --git a/arch/m68k/include/asm/raw_io.h b/arch/m68k/include/asm/raw_io.h
index 85761255dde5afaaf10bb29c1a54fa0f2435af90..8a6dc6e5a279cec9bbf8820f8a3c5153c38106f6 100644 (file)
--- a/arch/m68k/include/asm/raw_io.h
+++ b/arch/m68k/include/asm/raw_io.h
@@ -107,12 +107,43 @@ static inline void raw_insb(volatile u8 __iomem *port, u8 *buf, unsigned int len
 }
 
 static inline void raw_outsb(volatile u8 __iomem *port, const u8 *buf,
-                            unsigned int len)
+                            unsigned int nr)
 {
-       unsigned int i;
+       unsigned int tmp;
 
-        for (i = 0; i < len; i++)
-               out_8(port, *buf++);
+       if (nr & 15) {
+               tmp = (nr & 15) - 1;
+               asm volatile (
+                       "1: moveb %0@+,%2@; dbra %1,1b"
+                       : "=a" (buf), "=d" (tmp)
+                       : "a" (port), "0" (buf),
+                         "1" (tmp));
+       }
+       if (nr >> 4) {
+               tmp = (nr >> 4) - 1;
+               asm volatile (
+                       "1: "
+                       "moveb %0@+,%2@; "
+                       "moveb %0@+,%2@; "
+                       "moveb %0@+,%2@; "
+                       "moveb %0@+,%2@; "
+                       "moveb %0@+,%2@; "
+                       "moveb %0@+,%2@; "
+                       "moveb %0@+,%2@; "
+                       "moveb %0@+,%2@; "
+                       "moveb %0@+,%2@; "
+                       "moveb %0@+,%2@; "
+                       "moveb %0@+,%2@; "
+                       "moveb %0@+,%2@; "
+                       "moveb %0@+,%2@; "
+                       "moveb %0@+,%2@; "
+                       "moveb %0@+,%2@; "
+                       "moveb %0@+,%2@; "
+                       "dbra %1,1b"
+                       : "=a" (buf), "=d" (tmp)
+                       : "a" (port), "0" (buf),
+                         "1" (tmp));
+       }
 }
 
 static inline void raw_insw(volatile u16 __iomem *port, u16 *buf, unsigned int nr)