/*
   * sound/oss/pas2_midi.c
   *
   * The low level driver for the PAS Midi Interface.
   */
  /*
   * Copyright (C) by Hannu Savolainen 1993-1997
   *
   * OSS/Free for Linux is distributed under the GNU GENERAL PUBLIC LICENSE (GPL)
   * Version 2 (June 1991). See the "COPYING" file distributed with this software
   * for more info.
   *
   * Bartlomiej Zolnierkiewicz	: Added __init to pas_init_mixer()
   */
  
  #include <linux/init.h>
  #include <linux/spinlock.h>
  #include "sound_config.h"
  
  #include "pas2.h"
  
  extern spinlock_t pas_lock;
  
  static int      midi_busy, input_opened;
  static int      my_dev;
  
  int pas2_mididev=-1;
  
  static unsigned char tmp_queue[256];
  static volatile int qlen;
  static volatile unsigned char qhead, qtail;
  
  static void     (*midi_input_intr) (int dev, unsigned char data);
  
  static int pas_midi_open(int dev, int mode,
  	      void            (*input) (int dev, unsigned char data),
  	      void            (*output) (int dev)
  )
  {
  	int             err;
  	unsigned long   flags;
  	unsigned char   ctrl;
  
  
  	if (midi_busy)
  		return -EBUSY;
  
  	/*
  	 * Reset input and output FIFO pointers
  	 */
  	pas_write(0x20 | 0x40,
  		  0x178b);
  
  	spin_lock_irqsave(&pas_lock, flags);
  
  	if ((err = pas_set_intr(0x10)) < 0)
  	{
  		spin_unlock_irqrestore(&pas_lock, flags);
  		return err;
  	}
  	/*
  	 * Enable input available and output FIFO empty interrupts
  	 */
  
  	ctrl = 0;
  	input_opened = 0;
  	midi_input_intr = input;
  
  	if (mode == OPEN_READ || mode == OPEN_READWRITE)
  	{
  		ctrl |= 0x04;	/* Enable input */
  		input_opened = 1;
  	}
  	if (mode == OPEN_WRITE || mode == OPEN_READWRITE)
  	{
  		ctrl |= 0x08 | 0x10;	/* Enable output */
  	}
  	pas_write(ctrl, 0x178b);
  
  	/*
  	 * Acknowledge any pending interrupts
  	 */
  
  	pas_write(0xff, 0x1B88);
  
  	spin_unlock_irqrestore(&pas_lock, flags);
  
  	midi_busy = 1;
  	qlen = qhead = qtail = 0;
  	return 0;
  }
  
  static void pas_midi_close(int dev)
  {
  
  	/*
  	 * Reset FIFO pointers, disable intrs
  	 */
  	pas_write(0x20 | 0x40, 0x178b);
  
  	pas_remove_intr(0x10);
  	midi_busy = 0;
  }
  
  static int dump_to_midi(unsigned char midi_byte)
  {
  	int fifo_space, x;
  
  	fifo_space = ((x = pas_read(0x1B89)) >> 4) & 0x0f;
  
  	/*
  	 * The MIDI FIFO space register and it's documentation is nonunderstandable.
  	 * There seem to be no way to differentiate between buffer full and buffer
  	 * empty situations. For this reason we don't never write the buffer
  	 * completely full. In this way we can assume that 0 (or is it 15)
  	 * means that the buffer is empty.
  	 */
  
  	if (fifo_space < 2 && fifo_space != 0)	/* Full (almost) */
  		return 0;	/* Ask upper layers to retry after some time */
  
  	pas_write(midi_byte, 0x178A);
  
  	return 1;
  }
  
  static int pas_midi_out(int dev, unsigned char midi_byte)
  {
  
  	unsigned long flags;
  
  	/*
  	 * Drain the local queue first
  	 */
  
  	spin_lock_irqsave(&pas_lock, flags);
  
  	while (qlen && dump_to_midi(tmp_queue[qhead]))
  	{
  		qlen--;
  		qhead++;
  	}
  
  	spin_unlock_irqrestore(&pas_lock, flags);
  
  	/*
  	 *	Output the byte if the local queue is empty.
  	 */
  
  	if (!qlen)
  		if (dump_to_midi(midi_byte))
  			return 1;
  
  	/*
  	 *	Put to the local queue
  	 */
  
  	if (qlen >= 256)
  		return 0;	/* Local queue full */
  
  	spin_lock_irqsave(&pas_lock, flags);
  
  	tmp_queue[qtail] = midi_byte;
  	qlen++;
  	qtail++;
  
  	spin_unlock_irqrestore(&pas_lock, flags);
  
  	return 1;
  }
  
  static int pas_midi_start_read(int dev)
  {
  	return 0;
  }
  
  static int pas_midi_end_read(int dev)
  {
  	return 0;
  }
  
  static void pas_midi_kick(int dev)
  {
  }
  
  static int pas_buffer_status(int dev)
  {
  	return qlen;
  }
  
  #define MIDI_SYNTH_NAME	"Pro Audio Spectrum Midi"
  #define MIDI_SYNTH_CAPS	SYNTH_CAP_INPUT
  #include "midi_synth.h"
  
  static struct midi_operations pas_midi_operations =
  {
  	.owner		= THIS_MODULE,
  	.info		= {"Pro Audio Spectrum", 0, 0, SNDCARD_PAS},
  	.converter	= &std_midi_synth,
  	.in_info	= {0},
  	.open		= pas_midi_open,
  	.close		= pas_midi_close,
  	.outputc	= pas_midi_out,
  	.start_read	= pas_midi_start_read,
  	.end_read	= pas_midi_end_read,
  	.kick		= pas_midi_kick,
  	.buffer_status	= pas_buffer_status,
  };
  
  void __init pas_midi_init(void)
  {
  	int dev = sound_alloc_mididev();
  
  	if (dev == -1)
  	{
  		printk(KERN_WARNING "pas_midi_init: Too many midi devices detected
  ");
  		return;
  	}
  	std_midi_synth.midi_dev = my_dev = dev;
  	midi_devs[dev] = &pas_midi_operations;
  	pas2_mididev = dev;
  	sequencer_init();
  }
  
  void pas_midi_interrupt(void)
  {
  	unsigned char   stat;
  	int             i, incount;
  
  	stat = pas_read(0x1B88);
  
  	if (stat & 0x04)	/* Input data available */
  	{
  		incount = pas_read(0x1B89) & 0x0f;	/* Input FIFO size */
  		if (!incount)
  			incount = 16;
  
  		for (i = 0; i < incount; i++)
  			if (input_opened)
  			{
  				midi_input_intr(my_dev, pas_read(0x178A));
  			} else
  				pas_read(0x178A);	/* Flush */
  	}
  	if (stat & (0x08 | 0x10))
  	{
  		spin_lock(&pas_lock);/* called in irq context */
  
  		while (qlen && dump_to_midi(tmp_queue[qhead]))
  		{
  			qlen--;
  			qhead++;
  		}
  
  		spin_unlock(&pas_lock);
  	}
  	if (stat & 0x40)
  	{
  		printk(KERN_WARNING "MIDI output overrun %x,%x
  ", pas_read(0x1B89), stat);
  	}
  	pas_write(stat, 0x1B88);	/* Acknowledge interrupts */
  }