Commit 8318f7c2 authored by Guo Ren's avatar Guo Ren
Browse files

csky: optimize memcpy_{from,to}io() and memset_io() 



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 & arm64.

Signed-off-by: default avatarGuo Ren <guoren@linux.alibaba.com>
Signed-off-by: default avatarGuo Ren <guoren@kernel.org>
parent e4df2d5e

arch/csky/include/asm/io.h

+11 −0
Original line number Diff line number Diff line
@@ -31,6 +31,17 @@ 
#define writel(v,c)		({ wmb(); writel_relaxed((v),(c)); mb(); })

#endif



/*

 * String version of I/O memory access operations.

 */

extern void __memcpy_fromio(void *, const volatile void __iomem *, size_t);

extern void __memcpy_toio(volatile void __iomem *, const void *, size_t);

extern void __memset_io(volatile void __iomem *, int, size_t);



#define memset_io(c,v,l)        __memset_io((c),(v),(l))

#define memcpy_fromio(a,c,l)    __memcpy_fromio((a),(c),(l))

#define memcpy_toio(c,a,l)      __memcpy_toio((c),(a),(l))



/*

 * I/O memory mapping functions.

 */

arch/csky/kernel/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -2,7 +2,7 @@ 
extra-y := head.o vmlinux.lds



obj-y += entry.o atomic.o signal.o traps.o irq.o time.o vdso.o vdso/

obj-y += power.o syscall.o syscall_table.o setup.o

obj-y += power.o syscall.o syscall_table.o setup.o io.o

obj-y += process.o cpu-probe.o ptrace.o stacktrace.o

obj-y += probes/

arch/csky/kernel/io.c

0 → 100644
+91 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0



#include <linux/export.h>

#include <linux/types.h>

#include <linux/io.h>



/*

 * Copy data from IO memory space to "real" memory space.

 */

void __memcpy_fromio(void *to, const volatile void __iomem *from, size_t count)

{

	while (count && !IS_ALIGNED((unsigned long)from, 4)) {

		*(u8 *)to = __raw_readb(from);

		from++;

		to++;

		count--;

	}



	while (count >= 4) {

		*(u32 *)to = __raw_readl(from);

		from += 4;

		to += 4;

		count -= 4;

	}



	while (count) {

		*(u8 *)to = __raw_readb(from);

		from++;

		to++;

		count--;

	}

}

EXPORT_SYMBOL(__memcpy_fromio);



/*

 * Copy data from "real" memory space to IO memory space.

 */

void __memcpy_toio(volatile void __iomem *to, const void *from, size_t count)

{

	while (count && !IS_ALIGNED((unsigned long)to, 4)) {

		__raw_writeb(*(u8 *)from, to);

		from++;

		to++;

		count--;

	}



	while (count >= 4) {

		__raw_writel(*(u32 *)from, to);

		from += 4;

		to += 4;

		count -= 4;

	}



	while (count) {

		__raw_writeb(*(u8 *)from, to);

		from++;

		to++;

		count--;

	}

}

EXPORT_SYMBOL(__memcpy_toio);



/*

 * "memset" on IO memory space.

 */

void __memset_io(volatile void __iomem *dst, int c, size_t count)

{

	u32 qc = (u8)c;



	qc |= qc << 8;

	qc |= qc << 16;



	while (count && !IS_ALIGNED((unsigned long)dst, 4)) {

		__raw_writeb(c, dst);

		dst++;

		count--;

	}



	while (count >= 4) {

		__raw_writel(qc, dst);

		dst += 4;

		count -= 4;

	}



	while (count) {

		__raw_writeb(c, dst);

		dst++;

		count--;

	}

}

EXPORT_SYMBOL(__memset_io);