sb_dsp.c

LINUX1.0内核源代码,学习LINUX编程的一定要看。

/*
 * sound/sb_dsp.c
 * 
 * The low level driver for the SoundBlaster DSP chip.
 * 
 * Copyright by Hannu Savolainen 1993
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer. 2.
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * 
 */

#include "sound_config.h"

#if defined(CONFIGURE_SOUNDCARD) && !defined(EXCLUDE_SB)

#include "sb.h"
#include "sb_mixer.h"
#undef SB_TEST_IRQ

int      sbc_base = 0;
static int      sbc_irq = 0;

/*
 * The DSP channel can be used either for input or output. Variable
 * 'sb_irq_mode' will be set when the program calls read or write first time
 * after open. Current version doesn't support mode changes without closing
 * and reopening the device. Support for this feature may be implemented in a
 * future version of this driver.
 */

int      sb_dsp_ok = 0;	/* Set to 1 after successful initialization */
static int      midi_disabled = 0;
int      sb_dsp_highspeed = 0;
static int	major=1, minor=0;	/* DSP version */
static int	dsp_stereo = 0;
static int      dsp_current_speed = DSP_DEFAULT_SPEED;
static int      sb16 = 0;
static int	irq_verified = 0;

int      sb_midi_mode = NORMAL_MIDI;
int      sb_midi_busy = 0;	/* 1 if the process has output to MIDI */
int      sb_dsp_busy = 0;

volatile int sb_irq_mode = IMODE_NONE;	/* IMODE_INPUT, IMODE_OUTPUT
						 * or IMODE_NONE */
static volatile int irq_ok = 0;

int      sb_dsp_model = 1;	/* 1=SB, 2=SB Pro */
int      sb_duplex_midi = 0;
static int      my_dev = 0;

volatile int sb_intr_active = 0;

static int      dsp_speed (int);
static int      dsp_set_stereo (int mode);
int      sb_dsp_command (unsigned char val);

#if !defined(EXCLUDE_MIDI) || !defined(EXCLUDE_AUDIO)

/* Common code for the midi and pcm functions */

int
sb_dsp_command (unsigned char val)
{
  int             i, limit;

  limit = GET_TIME () + 10;	/* The timeout is 0.1 secods */

  /*
   * Note! the i<500000 is an emergency exit. The sb_dsp_command() is sometimes
   * called while interrupts are disabled. This means that the timer is
   * disabled also. However the timeout situation is a abnormal condition.
   * Normally the DSP should be ready to accept commands after just couple of
   * loops.
   */

  for (i = 0; i < 500000 && GET_TIME () < limit; i++)
    {
      if ((INB (DSP_STATUS) & 0x80) == 0)
	{
	  OUTB (val, DSP_COMMAND);
	  return 1;
	}
    }

  printk ("SoundBlaster: DSP Command(%x) Timeout.\n", val);
  printk ("IRQ conflict???\n");
  return 0;
}

void
sbintr (int unit)
{
  int             status, data;

#ifndef EXCLUDE_SBPRO
  if (sb16)
    {
      unsigned char   src = sb_getmixer (IRQ_STAT);	/* Interrupt source register */

#ifndef EXCLUDE_SB16
      if (src & 3) sb16_dsp_interrupt(unit);

#ifndef EXCLUDE_MIDI
      if (src & 4) sb16midiintr (unit);			/* MPU401 interrupt */
#endif

#endif

      if (!(src & 1))
	return;			/* Not a DSP interupt */
    }
#endif

  status = INB (DSP_DATA_AVAIL);/* Clear interrupt */

  if (sb_intr_active)
    switch (sb_irq_mode)
      {
      case IMODE_OUTPUT:
	sb_intr_active = 0;
	DMAbuf_outputintr (my_dev, 1);
	break;

      case IMODE_INPUT:
	sb_intr_active = 0;
	DMAbuf_inputintr (my_dev);
	/* A complete buffer has been input. Let's start new one */
	break;

      case IMODE_INIT:
	sb_intr_active = 0;
	irq_ok = 1;
	break;

      case IMODE_MIDI:
	printk ("+");
	data = INB (DSP_READ);
	printk ("%x", data);

	break;

      default:
	printk ("SoundBlaster: Unexpected interrupt\n");
      }
}

static int sb_irq_usecount = 0;

int
sb_get_irq(void)
{
	int ok;

	if (!sb_irq_usecount)
	  if ((ok=snd_set_irq_handler(sbc_irq, sbintr))<0) return ok;

	sb_irq_usecount++;

	return 0; 
}

void 
sb_free_irq(void)
{
	if (!sb_irq_usecount) return;

	sb_irq_usecount--;

	if (!sb_irq_usecount) snd_release_irq(sbc_irq);
}

int
sb_reset_dsp (void)
{
  int             loopc;

  OUTB (1, DSP_RESET);
  tenmicrosec ();
  OUTB (0, DSP_RESET);
  tenmicrosec ();
  tenmicrosec ();
  tenmicrosec ();

  for (loopc = 0; loopc < 1000 && !(INB (DSP_DATA_AVAIL) & 0x80); loopc++);	/* Wait for data
										 * available status */

  if (INB (DSP_READ) != 0xAA)
    return 0;			/* Sorry */

  return 1;
}

#endif

#ifndef EXCLUDE_AUDIO

static void
dsp_speaker (char state)
{
  if (state)
    sb_dsp_command (DSP_CMD_SPKON);
  else
    sb_dsp_command (DSP_CMD_SPKOFF);
}

static int
dsp_speed (int speed)
{
  unsigned char   tconst;
  unsigned long   flags;

  if (speed < 4000)
    speed = 4000;

  if (speed > 44100)
    speed = 44100;		/* Invalid speed */

  if (sb_dsp_model == 1 && speed > 22050)
    speed = 22050;
  /* SB Classic doesn't support higher speed */


  if (dsp_stereo && speed > 22050)
    speed = 22050;
  /* Max. stereo speed is 22050 */

  if ((speed > 22050) && sb_midi_busy)
    {
      printk ("SB Warning: High speed DSP not possible simultaneously with MIDI output\n");
      speed = 22050;
    }

  if (dsp_stereo)
    speed *= 2;

  /* Now the speed should be valid */

  if (speed > 22050)
    {				/* High speed mode */
      int tmp;

      tconst = (unsigned char) ((65536 - 
      				((256000000+speed/2) / speed)) >> 8);
      sb_dsp_highspeed = 1;

      DISABLE_INTR (flags);
      if (sb_dsp_command (0x40))
	sb_dsp_command (tconst);
      RESTORE_INTR (flags);

      tmp = 65536 - (tconst << 8);
      speed = (256000000+tmp/2) / tmp;
    }
  else
    {
      int tmp;

      sb_dsp_highspeed = 0;
      tconst = (256 - ((1000000+speed/2) / speed)) & 0xff;

      DISABLE_INTR (flags);
      if (sb_dsp_command (0x40))	/* Set time constant */
	sb_dsp_command (tconst);
      RESTORE_INTR (flags);

      tmp = 256 - tconst;
      speed = (1000000+tmp/2) / tmp;
    }

  if (dsp_stereo)
    speed /= 2;

  dsp_current_speed = speed;
  return speed;
}

static int
dsp_set_stereo (int mode)
{
  dsp_stereo = 0;

#ifdef EXCLUDE_SBPRO
  return 0;
#else
  if (sb_dsp_model == 1 || sb16)
    return 0;			/* Sorry no stereo */

  if (mode && sb_midi_busy)
    {
      printk ("SB Warning: Stereo DSP not possible simultaneously with MIDI output\n");
      return 0;
    }

  dsp_stereo = !!mode;
  return dsp_stereo;
#endif
}

static void
sb_dsp_output_block (int dev, unsigned long buf, int count, 
		     int intrflag, int restart_dma)
{
  unsigned long   flags;

  if (!sb_irq_mode)
    dsp_speaker (ON);

  sb_irq_mode = IMODE_OUTPUT;
  DMAbuf_start_dma (dev, buf, count, DMA_MODE_WRITE);

  if (sound_dsp_dmachan[dev] > 3)
    count >>= 1;
  count--;

  if (sb_dsp_highspeed)
    {
      DISABLE_INTR (flags);
      if (sb_dsp_command (0x48))	/* High speed size */
	{
	  sb_dsp_command ((unsigned char)(count & 0xff));
	  sb_dsp_command ((unsigned char)((count >> 8) & 0xff));
	  sb_dsp_command (0x91);	/* High speed 8 bit DAC */
	}
      else
	printk ("SB Error: Unable to start (high speed) DAC\n");
      RESTORE_INTR (flags);
    }
  else
    {
      DISABLE_INTR (flags);
      if (sb_dsp_command (0x14))	/* 8-bit DAC (DMA) */
	{
	  sb_dsp_command ((unsigned char)(count & 0xff));
	  sb_dsp_command ((unsigned char)((count >> 8) & 0xff));
	}
      else
	printk ("SB Error: Unable to start DAC\n");
      RESTORE_INTR (flags);
    }
  sb_intr_active = 1;
}

static void
sb_dsp_start_input (int dev, unsigned long buf, int count, int intrflag,
		    int restart_dma)
{
  /* Start a DMA input to the buffer pointed by dmaqtail */

  unsigned long   flags;

  if (!sb_irq_mode)