path: root/sound/drivers/vx/vx_pcm.c

/*
 * Driver for Digigram VX soundcards
 *
 * PCM part
 *
 * Copyright (c) 2002,2003 by Takashi Iwai <tiwai@suse.de>
 *
 *   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
 *
 *
 * STRATEGY
 *  for playback, we send series of "chunks", which size is equal with the
 *  IBL size, typically 126 samples.  at each end of chunk, the end-of-buffer
 *  interrupt is notified, and the interrupt handler will feed the next chunk.
 *
 *  the current position is calculated from the sample count RMH.
 *  pipe->transferred is the counter of data which has been already transferred.
 *  if this counter reaches to the period size, snd_pcm_period_elapsed() will
 *  be issued.
 *
 *  for capture, the situation is much easier.
 *  to get a low latency response, we'll check the capture streams at each
 *  interrupt (capture stream has no EOB notification).  if the pending
 *  data is accumulated to the period size, snd_pcm_period_elapsed() is
 *  called and the pointer is updated.
 *
 *  the current point of read buffer is kept in pipe->hw_ptr.  note that
 *  this is in bytes.
 *
 *
 * TODO
 *  - linked trigger for full-duplex mode.
 *  - scheduled action on the stream.
 */

#include <sound/driver.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/delay.h>
#include <sound/core.h>
#include <sound/asoundef.h>
#include <sound/pcm.h>
#include <sound/vx_core.h>
#include "vx_cmd.h"


/*
 * we use a vmalloc'ed (sg-)buffer
 */

/* get the physical page pointer on the given offset */
static struct page *snd_pcm_get_vmalloc_page(snd_pcm_substream_t *subs, unsigned long offset)
{
	void *pageptr = subs->runtime->dma_area + offset;
	return vmalloc_to_page(pageptr);
}

/*
 * allocate a buffer via vmalloc_32().
 * called from hw_params
 * NOTE: this may be called not only once per pcm open!
 */
static int snd_pcm_alloc_vmalloc_buffer(snd_pcm_substream_t *subs, size_t size)
{
	snd_pcm_runtime_t *runtime = subs->runtime;
	if (runtime->dma_area) {
		/* already allocated */
		if (runtime->dma_bytes >= size)
			return 0; /* already enough large */
		vfree(runtime->dma_area);
	}
	runtime->dma_area = vmalloc_32(size);
	if (! runtime->dma_area)
		return -ENOMEM;
	memset(runtime->dma_area, 0, size);
	runtime->dma_bytes = size;
	return 1; /* changed */
}

/*
 * free the buffer.
 * called from hw_free callback
 * NOTE: this may be called not only once per pcm open!
 */
static int snd_pcm_free_vmalloc_buffer(snd_pcm_substream_t *subs)
{
	snd_pcm_runtime_t *runtime = subs->runtime;
	if (runtime->dma_area) {
		vfree(runtime->dma_area);
		runtime->dma_area = NULL;
	}
	return 0;
}


/*
 * read three pending pcm bytes via inb()
 */
static void vx_pcm_read_per_bytes(vx_core_t *chip, snd_pcm_runtime_t *runtime, vx_pipe_t *pipe)
{
	int