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sound/core/isadma.c
3.02 KB
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/*
* ISA DMA support functions
* Copyright (c) by Jaroslav Kysela <perex@perex.cz>
*
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
/*
* Defining following add some delay. Maybe this helps for some broken
* ISA DMA controllers.
*/
#undef HAVE_REALLY_SLOW_DMA_CONTROLLER
#include <linux/export.h>
#include <sound/core.h>
#include <asm/dma.h>
/**
* snd_dma_program - program an ISA DMA transfer
* @dma: the dma number
* @addr: the physical address of the buffer
* @size: the DMA transfer size
* @mode: the DMA transfer mode, DMA_MODE_XXX
*
* Programs an ISA DMA transfer for the given buffer.
*/
void snd_dma_program(unsigned long dma,
unsigned long addr, unsigned int size,
unsigned short mode)
{
unsigned long flags;
flags = claim_dma_lock();
disable_dma(dma);
clear_dma_ff(dma);
set_dma_mode(dma, mode);
set_dma_addr(dma, addr);
set_dma_count(dma, size);
if (!(mode & DMA_MODE_NO_ENABLE))
enable_dma(dma);
release_dma_lock(flags);
}
EXPORT_SYMBOL(snd_dma_program);
/**
* snd_dma_disable - stop the ISA DMA transfer
* @dma: the dma number
*
* Stops the ISA DMA transfer.
*/
void snd_dma_disable(unsigned long dma)
{
unsigned long flags;
flags = claim_dma_lock();
clear_dma_ff(dma);
disable_dma(dma);
release_dma_lock(flags);
}
EXPORT_SYMBOL(snd_dma_disable);
/**
* snd_dma_pointer - return the current pointer to DMA transfer buffer in bytes
* @dma: the dma number
* @size: the dma transfer size
*
* Return: The current pointer in DMA transfer buffer in bytes.
*/
unsigned int snd_dma_pointer(unsigned long dma, unsigned int size)
{
unsigned long flags;
unsigned int result, result1;
flags = claim_dma_lock();
clear_dma_ff(dma);
if (!isa_dma_bridge_buggy)
disable_dma(dma);
result = get_dma_residue(dma);
/*
* HACK - read the counter again and choose higher value in order to
* avoid reading during counter lower byte roll over if the
* isa_dma_bridge_buggy is set.
*/
result1 = get_dma_residue(dma);
if (!isa_dma_bridge_buggy)
enable_dma(dma);
release_dma_lock(flags);
if (unlikely(result < result1))
result = result1;
#ifdef CONFIG_SND_DEBUG
if (result > size)
pr_err("ALSA: pointer (0x%x) for DMA #%ld is greater than transfer size (0x%x)
", result, dma, size);
#endif
if (result >= size || result == 0)
return 0;
else
return size - result;
}
EXPORT_SYMBOL(snd_dma_pointer);
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