wavefront_midi.c

h内核

/*
 * Copyright (C) by Paul Barton-Davis 1998-1999
 *
 * This file is distributed under the GNU GENERAL PUBLIC LICENSE (GPL)
 * Version 2 (June 1991). See the "COPYING" file distributed with this
 * software for more info.  
 */

/* The low level driver for the WaveFront ICS2115 MIDI interface(s)
 *
 * Note that there is also an MPU-401 emulation (actually, a UART-401
 * emulation) on the CS4232 on the Tropez and Tropez Plus. This code
 * has nothing to do with that interface at all.
 *
 * The interface is essentially just a UART-401, but is has the
 * interesting property of supporting what Turtle Beach called
 * "Virtual MIDI" mode. In this mode, there are effectively *two*
 * MIDI buses accessible via the interface, one that is routed
 * solely to/from the external WaveFront synthesizer and the other
 * corresponding to the pin/socket connector used to link external
 * MIDI devices to the board.
 *
 * This driver fully supports this mode, allowing two distinct MIDI
 * busses to be used completely independently, giving 32 channels of
 * MIDI routing, 16 to the WaveFront synth and 16 to the external MIDI
 * bus. The devices are named /dev/snd/midiCnD0 and /dev/snd/midiCnD1,
 * where `n' is the card number. Note that the device numbers may be
 * something other than 0 and 1 if the CS4232 UART/MPU-401 interface
 * is enabled.
 *
 * Switching between the two is accomplished externally by the driver
 * using the two otherwise unused MIDI bytes. See the code for more details.
 *
 * NOTE: VIRTUAL MIDI MODE IS ON BY DEFAULT (see lowlevel/isa/wavefront.c)
 *
 * The main reason to turn off Virtual MIDI mode is when you want to
 * tightly couple the WaveFront synth with an external MIDI
 * device. You won't be able to distinguish the source of any MIDI
 * data except via SysEx ID, but thats probably OK, since for the most
 * part, the WaveFront won't be sending any MIDI data at all.
 *  
 * The main reason to turn on Virtual MIDI Mode is to provide two
 * completely independent 16-channel MIDI buses, one to the
 * WaveFront and one to any external MIDI devices. Given the 32
 * voice nature of the WaveFront, its pretty easy to find a use
 * for all 16 channels driving just that synth.
 *  
 */

#include <sound/driver.h>
#include <asm/io.h>
#include <linux/init.h>
#include <linux/time.h>
#include <linux/wait.h>
#include <sound/core.h>
#include <sound/snd_wavefront.h>

static inline int 
wf_mpu_status (snd_wavefront_midi_t *midi)

{
	return inb (midi->mpu_status_port);
}

static inline int 
input_avail (snd_wavefront_midi_t *midi)

{
	return !(wf_mpu_status(midi) & INPUT_AVAIL);
}

static inline int
output_ready (snd_wavefront_midi_t *midi)

{
	return !(wf_mpu_status(midi) & OUTPUT_READY);
}

static inline int 
read_data (snd_wavefront_midi_t *midi)

{
	return inb (midi->mpu_data_port);
}

static inline void 
write_data (snd_wavefront_midi_t *midi, unsigned char byte)

{
	outb (byte, midi->mpu_data_port);
}

static snd_wavefront_midi_t *
get_wavefront_midi (snd_rawmidi_substream_t *substream)

{
	snd_card_t *card;
	snd_wavefront_card_t *acard;

	if (substream == NULL || substream->rmidi == NULL) 
	        return NULL;

	card = substream->rmidi->card;

	if (card == NULL) 
	        return NULL;

	if (card->private_data == NULL) 
 	        return NULL;

	acard = card->private_data;

	return &acard->wavefront.midi;
}

static void snd_wavefront_midi_output_write(snd_wavefront_card_t *card)
{
	snd_wavefront_midi_t *midi = &card->wavefront.midi;
	snd_wavefront_mpu_id  mpu;
	unsigned long flags;
	unsigned char midi_byte;
	int max = 256, mask = 1;
	int timeout;

	/* Its not OK to try to change the status of "virtuality" of
	   the MIDI interface while we're outputting stuff.  See
	   snd_wavefront_midi_{enable,disable}_virtual () for the
	   other half of this.  

	   The first loop attempts to flush any data from the
	   current output device, and then the second 
	   emits the switch byte (if necessary), and starts
	   outputting data for the output device currently in use.
	*/

	if (midi->substream_output[midi->output_mpu] == NULL) {
		goto __second;
	}

	while (max > 0) {

		/* XXX fix me - no hard timing loops allowed! */

		for (timeout = 30000; timeout > 0; timeout--) {
			if (output_ready (midi))
				break;
		}
	
		spin_lock_irqsave (&midi->virtual, flags);
		if ((midi->mode[midi->output_mpu] & MPU401_MODE_OUTPUT) == 0) {
			spin_unlock_irqrestore (&midi->virtual, flags);
			goto __second;
		}
		if (output_ready (midi)) {
			if (snd_rawmidi_transmit(midi->substream_output[midi->output_mpu], &midi_byte, 1) == 1) {
				if (!midi->isvirtual ||
					(midi_byte != WF_INTERNAL_SWITCH &&
					 midi_byte != WF_EXTERNAL_SWITCH))
					write_data(midi, midi_byte);
				max--;
			} else {
				if (midi->istimer) {
					if (--midi->istimer <= 0)
						del_timer(&midi->timer);
				}
				midi->mode[midi->output_mpu] &= ~MPU401_MODE_OUTPUT_TRIGGER;
				spin_unlock_irqrestore (&midi->virtual, flags);
				goto __second;
			}
		} else {
			spin_unlock_irqrestore (&midi->virtual, flags);
			return;
		}
		spin_unlock_irqrestore (&midi->virtual, flags);
	}

      __second:

	if (midi->substream_output[!midi->output_mpu] == NULL) {
		return;
	}

	while (max > 0) {

		/* XXX fix me - no hard timing loops allowed! */

		for (timeout = 30000; timeout > 0; timeout--) {
			if (output_ready (midi))
				break;
		}
	
		spin_lock_irqsave (&midi->virtual, flags);
		if (!midi->isvirtual)
			mask = 0;
		mpu = midi->output_mpu ^ mask;
		mask = 0;	/* don't invert the value from now */
		if ((midi->mode[mpu] & MPU401_MODE_OUTPUT) == 0) {
			spin_unlock_irqrestore (&midi->virtual, flags);
			return;
		}
		if (snd_rawmidi_transmit_empty(midi->substream_output[mpu]))
			goto __timer;
		if (output_ready (midi)) {
			if (mpu != midi->output_mpu) {
				write_data(midi, mpu == internal_mpu ?
							WF_INTERNAL_SWITCH :
							WF_EXTERNAL_SWITCH);
				midi->output_mpu = mpu;
			} else if (snd_rawmidi_transmit(midi->substream_output[mpu], &midi_byte, 1) == 1) {
				if (!midi->isvirtual ||
					(midi_byte != WF_INTERNAL_SWITCH &&
					 midi_byte != WF_EXTERNAL_SWITCH))
					write_data(midi, midi_byte);
				max--;
			} else {
			      __timer:
				if (midi->istimer) {
					if (--midi->istimer <= 0)
						del_timer(&midi->timer);
				}
				midi->mode[mpu] &= ~MPU401_MODE_OUTPUT_TRIGGER;
				spin_unlock_irqrestore (&midi->virtual, flags);
				return;
			}
		} else {
			spin_unlock_irqrestore (&midi->virtual, flags);
			return;
		}
		spin_unlock_irqrestore (&midi->virtual, flags);
	}
}

static int snd_wavefront_midi_input_open(snd_rawmidi_substream_t * substream)
{
	unsigned long flags;
	snd_wavefront_midi_t *midi;
	snd_wavefront_mpu_id mpu;

	snd_assert(substream != NULL && substream->rmidi != NULL, return -EIO);
	snd_assert(substream->rmidi->private_data != NULL, return -EIO);

	mpu = *((snd_wavefront_mpu_id *) substream->rmidi->private_data);

	if ((midi = get_wavefront_midi (substream)) == NULL)
	        return -EIO;

	spin_lock_irqsave (&midi->open, flags);
	midi->mode[mpu] |= MPU401_MODE_INPUT;
	midi->substream_input[mpu] = substream;
	spin_unlock_irqrestore (&midi->open, flags);

	return 0;
}

static int snd_wavefront_midi_output_open(snd_rawmidi_substream_t * substream)
{
	unsigned long flags;
	snd_wavefront_midi_t *midi;
	snd_wavefront_mpu_id mpu;

	snd_assert(substream != NULL && substream->rmidi != NULL, return -EIO);
	snd_assert(substream->rmidi->private_data != NULL, return -EIO);

	mpu = *((snd_wavefront_mpu_id *) substream->rmidi->private_data);

	if ((midi = get_wavefront_midi (substream)) == NULL)
	        return -EIO;

	spin_lock_irqsave (&midi->open, flags);
	midi->mode[mpu] |= MPU401_MODE_OUTPUT;
	midi->substream_output[mpu] = substream;
	spin_unlock_irqrestore (&midi->open, flags);

	return 0;
}

static int snd_wavefront_midi_input_close(snd_rawmidi_substream_t * substream)
{
	unsigned long flags;
	snd_wavefront_midi_t *midi;
	snd_wavefront_mpu_id mpu;

	snd_assert(substream != NULL && substream->rmidi != NULL, return -EIO);
	snd_assert(substream->rmidi->private_data != NULL, return -EIO);

	mpu = *((snd_wavefront_mpu_id *) substream->rmidi->private_data);

	if ((midi = get_wavefront_midi (substream)) == NULL)