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[PATCH] Introduce __iowrite32_copy

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This arch-independent routine copies data to a memory-mapped I/O region,
using 32-bit accesses.  The naming is double-underscored to make it clear
that it does not guarantee write ordering, nor does it perform a memory
barrier afterwards; the kernel doc also explicitly states this.  This style
of access is required by some devices.

This change also introduces include/linux/io.h, at Andrew's suggestion.  It
only has one occupant at the moment, but is a logical destination for
oft-replicated contents of include/asm-*/{io,iomap}.h to migrate to.

Signed-off-by: Bryan O'Sullivan <bos@pathscale.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Bryan O'Sullivan 2006-02-01 03:05:16 -08:00 committed by Linus Torvalds
parent f7589f28d7
commit c27a0d75b3
3 changed files with 68 additions and 1 deletions
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25
include/linux/io.h Normal file
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@ -0,0 +1,25 @@
/*
* Copyright 2006 PathScale, Inc. All Rights Reserved.
*
* This file is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#ifndef _LINUX_IO_H
#define _LINUX_IO_H
#include <asm/io.h>
void __iowrite32_copy(void __iomem *to, const void *from, size_t count);
#endif /* _LINUX_IO_H */

2
lib/Makefile
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@ -9,7 +9,7 @@ lib-y := errno.o ctype.o string.o vsprintf.o cmdline.o \
lib-y += kobject.o kref.o kobject_uevent.o klist.o
obj-y += sort.o parser.o halfmd4.o
obj-y += sort.o parser.o halfmd4.o iomap_copy.o
ifeq ($(CONFIG_DEBUG_KOBJECT),y)
CFLAGS_kobject.o += -DDEBUG

42
lib/iomap_copy.c Normal file
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@ -0,0 +1,42 @@
/*
* Copyright 2006 PathScale, Inc. All Rights Reserved.
*
* This file is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <linux/io.h>
#include <linux/module.h>
/**
* __iowrite32_copy - copy data to MMIO space, in 32-bit units
* @to: destination, in MMIO space (must be 32-bit aligned)
* @from: source (must be 32-bit aligned)
* @count: number of 32-bit quantities to copy
*
* Copy data from kernel space to MMIO space, in units of 32 bits at a
* time. Order of access is not guaranteed, nor is a memory barrier
* performed afterwards.
*/
void __attribute__((weak)) __iowrite32_copy(void __iomem *to,
const void *from,
size_t count)
{
u32 __iomem *dst = to;
const u32 *src = from;
const u32 *end = src + count;
while (src < end)
__raw_writel(*src++, dst++);
}
EXPORT_SYMBOL_GPL(__iowrite32_copy);