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sh: Optimise memcpy_to/fromio for SH4

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Optimise memcpy_to/fromio. This is used extensivly by MTD, so is a
worthwhile performance gain. The main savings come from not repeatedly
calling readl/writel, and doing word instead of byte at a time
transfers. Also using "movca.l" on SH4 gives a small performance win.

Signed-off-by: Stuart Menefy <stuart.menefy@st.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Stuart Menefy 2009-08-24 17:35:07 +09:00 committed by Paul Mundt
parent 8af57f8b4c
commit 5e9377ec6f
1 changed files with 72 additions and 21 deletions
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93
arch/sh/kernel/io.c
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@ -1,12 +1,9 @@
/*
* linux/arch/sh/kernel/io.c
* arch/sh/kernel/io.c - Machine independent I/O functions.
*
* Copyright (C) 2000 Stuart Menefy
* Copyright (C) 2000 - 2009 Stuart Menefy
* Copyright (C) 2005 Paul Mundt
*
* Provide real functions which expand to whatever the header file defined.
* Also definitions of machine independent IO functions.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
@ -18,33 +15,87 @@
/*
* Copy data from IO memory space to "real" memory space.
* This needs to be optimized.
*/
void memcpy_fromio(void *to, const volatile void __iomem *from, unsigned long count)
{
unsigned char *p = to;
while (count) {
count--;
*p = readb(from);
p++;
from++;
}
/*
* Would it be worthwhile doing byte and long transfers first
* to try and get aligned?
*/
#ifdef CONFIG_CPU_SH4
if ((count >= 0x20) &&
(((u32)to & 0x1f) == 0) && (((u32)from & 0x3) == 0)) {
int tmp2, tmp3, tmp4, tmp5, tmp6;
__asm__ __volatile__(
"1: \n\t"
"mov.l @%7+, r0 \n\t"
"mov.l @%7+, %2 \n\t"
"movca.l r0, @%0 \n\t"
"mov.l @%7+, %3 \n\t"
"mov.l @%7+, %4 \n\t"
"mov.l @%7+, %5 \n\t"
"mov.l @%7+, %6 \n\t"
"mov.l @%7+, r7 \n\t"
"mov.l @%7+, r0 \n\t"
"mov.l %2, @(0x04,%0) \n\t"
"mov #0x20, %2 \n\t"
"mov.l %3, @(0x08,%0) \n\t"
"sub %2, %1 \n\t"
"mov.l %4, @(0x0c,%0) \n\t"
"cmp/hi %1, %2 ! T if 32 > count \n\t"
"mov.l %5, @(0x10,%0) \n\t"
"mov.l %6, @(0x14,%0) \n\t"
"mov.l r7, @(0x18,%0) \n\t"
"mov.l r0, @(0x1c,%0) \n\t"
"bf.s 1b \n\t"
" add #0x20, %0 \n\t"
: "=&r" (to), "=&r" (count),
"=&r" (tmp2), "=&r" (tmp3), "=&r" (tmp4),
"=&r" (tmp5), "=&r" (tmp6), "=&r" (from)
: "7"(from), "0" (to), "1" (count)
: "r0", "r7", "t", "memory");
}
#endif
if ((((u32)to | (u32)from) & 0x3) == 0) {
for (; count > 3; count -= 4) {
*(u32 *)to = *(volatile u32 *)from;
to += 4;
from += 4;
}
}
for (; count > 0; count--) {
*(u8 *)to = *(volatile u8 *)from;
to++;
from++;
}
mb();
}
EXPORT_SYMBOL(memcpy_fromio);
/*
* Copy data from "real" memory space to IO memory space.
* This needs to be optimized.
*/
void memcpy_toio(volatile void __iomem *to, const void *from, unsigned long count)
{
const unsigned char *p = from;
while (count) {
count--;
writeb(*p, to);
p++;
to++;
}
if ((((u32)to | (u32)from) & 0x3) == 0) {
for ( ; count > 3; count -= 4) {
*(volatile u32 *)to = *(u32 *)from;
to += 4;
from += 4;
}
}
for (; count > 0; count--) {
*(volatile u8 *)to = *(u8 *)from;
to++;
from++;
}
mb();
}
EXPORT_SYMBOL(memcpy_toio);