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 <linux/slab.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"


/*
 * read three pending pcm bytes via inb()
 */
static void vx_pcm_read_per_bytes(struct vx_core *chip, struct snd_pcm_runtime *runtime,
				  struct vx_pipe *pipe)
{
	int offset = pipe->hw_ptr;
	unsigned char *buf = (unsigned char *)(runtime->dma_area + offset);
	*buf++ = vx_inb(chip, RXH);
	if (++offset >= pipe->buffer_bytes) {
		offset = 0;
		buf = (unsigned char *)runtime->dma_area;
	}
	*buf++ = vx_inb(chip, RXM);
	if (++offset >= pipe->buffer_bytes) {
		offset = 0;
		buf = (unsigned char *)runtime->dma_area;
	}
	*buf++ = vx_inb(chip, RXL);
	if (++offset >= pipe->buffer_bytes) {
		offset = 0;
		buf = (unsigned char *)runtime->dma_area;
	}
	pipe->hw_ptr = offset;
}

/*
 * vx_set_pcx_time - convert from the PC time to the RMH status time.
 * @pc_time: the pointer for the PC-time to set
 * @dsp_time: the pointer for RMH status time array
 */
static void vx_set_pcx_time(struct vx_core *chip, pcx_time_t *pc_time,
			    unsigned int *dsp_time)
{
	dsp_time[0] = (unsigned int)((*pc_time) >> 24) & PCX_TIME_HI_MASK;
	dsp_time[1] = (unsigned int)(*pc_time) &  MASK_DSP_WORD;
}

/*
 * vx_set_differed_time - set the differed time if specified
 * @rmh: the rmh record to modify
 * @pipe: the pipe to be checked
 *
 * if the pipe is programmed with the differed time, set the DSP time
 * o