isadma.c

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/*
 *  ISA DMA support functions
 *  Copyright (c) by Jaroslav Kysela <[email protected]>
 *
 *
 *   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>

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);

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);

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)
        snd_printk(KERN_ERR "pointer (0x%x) for DMA #%ld is greater than transfer size (0x%x)\n", result, dma, size);
#endif
    if (result >= size || result == 0)
        return 0;
    else
        return size - result;
}

EXPORT_SYMBOL(snd_dma_pointer);