Logo Search packages:      
Sourcecode: alsa-driver version File versions

isadma.c

/*
 *  ISA DMA support functions
 *  Copyright (c) by Jaroslav Kysela <perex@suse.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 <sound/driver.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);
}

/**
 * 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);
}

/**
 * snd_dma_pointer - return the current pointer to DMA transfer buffer in bytes
 * @dma: the dma number
 * @size: the dma transfer size
 *
 * Returns the current pointer in DMA tranfer buffer in bytes
 */
unsigned int snd_dma_pointer(unsigned long dma, unsigned int size)
{
      unsigned long flags;
      unsigned int result;

      flags = claim_dma_lock();
      clear_dma_ff(dma);
      if (!isa_dma_bridge_buggy)
            disable_dma(dma);
      result = get_dma_residue(dma);
      if (!isa_dma_bridge_buggy)
            enable_dma(dma);
      release_dma_lock(flags);
#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;
}

Generated by  Doxygen 1.6.0   Back to index