96 строки
2.5 KiB
C
96 строки
2.5 KiB
C
|
/*
|
||
|
|
* arch/sh/mm/pg-dma.c
|
||
|
|
*
|
||
|
|
* Fast clear_page()/copy_page() implementation using the SH DMAC
|
||
|
|
*
|
||
|
|
* Copyright (C) 2003 Paul Mundt
|
||
|
|
*
|
||
|
|
* 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.
|
||
|
|
*/
|
||
|
|
#include <linux/init.h>
|
||
|
|
#include <linux/kernel.h>
|
||
|
|
#include <linux/module.h>
|
||
|
|
#include <asm/semaphore.h>
|
||
|
|
#include <asm/mmu_context.h>
|
||
|
|
#include <asm/addrspace.h>
|
||
|
|
#include <asm/atomic.h>
|
||
|
|
#include <asm/page.h>
|
||
|
|
#include <asm/dma.h>
|
||
|
|
#include <asm/io.h>
|
||
|
|
|
||
|
|
/* Channel to use for page ops, must be dual-address mode capable. */
|
||
|
|
static int dma_channel = CONFIG_DMA_PAGE_OPS_CHANNEL;
|
||
|
|
|
||
|
|
static void copy_page_dma(void *to, void *from)
|
||
|
|
{
|
||
|
|
/*
|
||
|
|
* This doesn't seem to get triggered until further along in the
|
||
|
|
* boot process, at which point the DMAC is already initialized.
|
||
|
|
* Fix this in the same fashion as clear_page_dma() in the event
|
||
|
|
* that this crashes due to the DMAC not being initialized.
|
||
|
|
*/
|
||
|
|
|
||
|
|
flush_icache_range((unsigned long)from, PAGE_SIZE);
|
||
|
|
dma_write_page(dma_channel, (unsigned long)from, (unsigned long)to);
|
||
|
|
dma_wait_for_completion(dma_channel);
|
||
|
|
}
|
||
|
|
|
||
|
|
static void clear_page_dma(void *to)
|
||
|
|
{
|
||
|
|
/*
|
||
|
|
* We get invoked quite early on, if the DMAC hasn't been initialized
|
||
|
|
* yet, fall back on the slow manual implementation.
|
||
|
|
*/
|
||
|
|
if (dma_info[dma_channel].chan != dma_channel) {
|
||
|
|
clear_page_slow(to);
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
|
||
|
|
dma_write_page(dma_channel, (unsigned long)empty_zero_page,
|
||
|
|
(unsigned long)to);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* FIXME: Something is a bit racy here, if we poll the counter right
|
||
|
|
* away, we seem to lock. flushing the page from the dcache doesn't
|
||
|
|
* seem to make a difference one way or the other, though either a full
|
||
|
|
* icache or dcache flush does.
|
||
|
|
*
|
||
|
|
* The location of this is important as well, and must happen prior to
|
||
|
|
* the completion loop but after the transfer was initiated.
|
||
|
|
*
|
||
|
|
* Oddly enough, this doesn't appear to be an issue for copy_page()..
|
||
|
|
*/
|
||
|
|
flush_icache_range((unsigned long)to, PAGE_SIZE);
|
||
|
|
|
||
|
|
dma_wait_for_completion(dma_channel);
|
||
|
|
}
|
||
|
|
|
||
|
|
static int __init pg_dma_init(void)
|
||
|
|
{
|
||
|
|
int ret;
|
||
|
|
|
||
|
|
ret = request_dma(dma_channel, "page ops");
|
||
|
|
if (ret != 0)
|
||
|
|
return ret;
|
||
|
|
|
||
|
|
copy_page = copy_page_dma;
|
||
|
|
clear_page = clear_page_dma;
|
||
|
|
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
static void __exit pg_dma_exit(void)
|
||
|
|
{
|
||
|
|
free_dma(dma_channel);
|
||
|
|
}
|
||
|
|
|
||
|
|
module_init(pg_dma_init);
|
||
|
|
module_exit(pg_dma_exit);
|
||
|
|
|
||
|
|
MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
|
||
|
|
MODULE_DESCRIPTION("Optimized page copy/clear routines using a dual-address mode capable DMAC channel");
|
||
|
|
MODULE_LICENSE("GPL");
|
||
|
|
|