mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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70ddb63a88
Optimize memcpy_{from,to}io() and memset_io() by transferring in 64 bit
as much as possible with minimized barrier usage. This simplest
optimization brings faster throughput compare to current byte-by-byte read
and write with barrier in the loop. Code's skeleton is taken from the
powerpc.
Link: http://lkml.kernel.org/p/20141020133304.GH23751@e104818-lin.cambridge.arm.com
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Trilok Soni <tsoni@codeaurora.org>
Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
111 lines
2.2 KiB
C
111 lines
2.2 KiB
C
/*
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* Based on arch/arm/kernel/io.c
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*
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* Copyright (C) 2012 ARM Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/export.h>
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#include <linux/types.h>
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#include <linux/io.h>
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/*
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* Copy data from IO memory space to "real" memory space.
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*/
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void __memcpy_fromio(void *to, const volatile void __iomem *from, size_t count)
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{
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while (count && (!IS_ALIGNED((unsigned long)from, 8) ||
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!IS_ALIGNED((unsigned long)to, 8))) {
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*(u8 *)to = __raw_readb(from);
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from++;
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to++;
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count--;
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}
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while (count >= 8) {
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*(u64 *)to = __raw_readq(from);
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from += 8;
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to += 8;
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count -= 8;
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}
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while (count) {
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*(u8 *)to = __raw_readb(from);
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from++;
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to++;
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count--;
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}
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}
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EXPORT_SYMBOL(__memcpy_fromio);
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/*
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* Copy data from "real" memory space to IO memory space.
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*/
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void __memcpy_toio(volatile void __iomem *to, const void *from, size_t count)
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{
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while (count && (!IS_ALIGNED((unsigned long)to, 8) ||
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!IS_ALIGNED((unsigned long)from, 8))) {
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__raw_writeb(*(volatile u8 *)from, to);
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from++;
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to++;
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count--;
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}
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while (count >= 8) {
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__raw_writeq(*(volatile u64 *)from, to);
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from += 8;
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to += 8;
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count -= 8;
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}
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while (count) {
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__raw_writeb(*(volatile u8 *)from, to);
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from++;
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to++;
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count--;
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}
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}
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EXPORT_SYMBOL(__memcpy_toio);
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/*
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* "memset" on IO memory space.
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*/
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void __memset_io(volatile void __iomem *dst, int c, size_t count)
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{
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u64 qc = (u8)c;
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qc |= qc << 8;
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qc |= qc << 16;
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qc |= qc << 32;
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while (count && !IS_ALIGNED((unsigned long)dst, 8)) {
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__raw_writeb(c, dst);
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dst++;
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count--;
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}
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while (count >= 8) {
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__raw_writeq(qc, dst);
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dst += 8;
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count -= 8;
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}
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while (count) {
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__raw_writeb(c, dst);
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dst++;
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count--;
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}
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}
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EXPORT_SYMBOL(__memset_io);
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