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m68k: Unroll raw_outsb() loop

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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>
This commit is contained in:
Finn Thain 2018-10-13 11:47:55 +11:00 committed by Geert Uytterhoeven
parent 651022382c
commit b6cf523c16
1 changed files with 35 additions and 4 deletions
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39
arch/m68k/include/asm/raw_io.h
View file

@ -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)