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seq_midi.c

/*
 *   Generic MIDI synth driver for ALSA sequencer
 *   Copyright (c) 1998 by Frank van de Pol <fvdpol@coil.demon.nl>
 *                         Jaroslav Kysela <perex@suse.cz>
 *
 *   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
 *
 */
 
/* 
Possible options for midisynth module:
      - automatic opening of midi ports on first received event or subscription
        (close will be performed when client leaves)
*/


#include <sound/driver.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/moduleparam.h>
#include <asm/semaphore.h>
#include <sound/core.h>
#include <sound/rawmidi.h>
#include <sound/seq_kernel.h>
#include <sound/seq_device.h>
#include <sound/seq_midi_event.h>
#include <sound/initval.h>

MODULE_AUTHOR("Frank van de Pol <fvdpol@coil.demon.nl>, Jaroslav Kysela <perex@suse.cz>");
MODULE_DESCRIPTION("Advanced Linux Sound Architecture sequencer MIDI synth.");
MODULE_LICENSE("GPL");
static int output_buffer_size = PAGE_SIZE;
module_param(output_buffer_size, int, 0644);
MODULE_PARM_DESC(output_buffer_size, "Output buffer size in bytes.");
static int input_buffer_size = PAGE_SIZE;
module_param(input_buffer_size, int, 0644);
MODULE_PARM_DESC(input_buffer_size, "Input buffer size in bytes.");

/* data for this midi synth driver */
typedef struct {
      snd_card_t *card;
      int device;
      int subdevice;
      snd_rawmidi_file_t input_rfile;
      snd_rawmidi_file_t output_rfile;
      int seq_client;
      int seq_port;
      snd_midi_event_t *parser;
} seq_midisynth_t;

typedef struct {
      int seq_client;
      int num_ports;
      int ports_per_device[SNDRV_RAWMIDI_DEVICES];
      seq_midisynth_t *ports[SNDRV_RAWMIDI_DEVICES];
} seq_midisynth_client_t;

static seq_midisynth_client_t *synths[SNDRV_CARDS];
static DECLARE_MUTEX(register_mutex);

/* handle rawmidi input event (MIDI v1.0 stream) */
static void snd_midi_input_event(snd_rawmidi_substream_t * substream)
{
      snd_rawmidi_runtime_t *runtime;
      seq_midisynth_t *msynth;
      snd_seq_event_t ev;
      char buf[16], *pbuf;
      long res, count;

      if (substream == NULL)
            return;
      runtime = substream->runtime;
      msynth = (seq_midisynth_t *) runtime->private_data;
      if (msynth == NULL)
            return;
      memset(&ev, 0, sizeof(ev));
      while (runtime->avail > 0) {
            res = snd_rawmidi_kernel_read(substream, buf, sizeof(buf));
            if (res <= 0)
                  continue;
            if (msynth->parser == NULL)
                  continue;
            pbuf = buf;
            while (res > 0) {
                  count = snd_midi_event_encode(msynth->parser, pbuf, res, &ev);
                  if (count < 0)
                        break;
                  pbuf += count;
                  res -= count;
                  if (ev.type != SNDRV_SEQ_EVENT_NONE) {
                        ev.source.port = msynth->seq_port;
                        ev.dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS;
                        snd_seq_kernel_client_dispatch(msynth->seq_client, &ev, 1, 0);
                        /* clear event and reset header */
                        memset(&ev, 0, sizeof(ev));
                  }
            }
      }
}

static int dump_midi(snd_rawmidi_substream_t *substream, const char *buf, int count)
{
      snd_rawmidi_runtime_t *runtime;
      int tmp;

      snd_assert(substream != NULL || buf != NULL, return -EINVAL);
      runtime = substream->runtime;
      if ((tmp = runtime->avail) < count) {
            snd_printd("warning, output event was lost (count = %i, available = %i)\n", count, tmp);
            return -ENOMEM;
      }
      if (snd_rawmidi_kernel_write(substream, buf, count) < count)
            return -EINVAL;
      return 0;
}

static int event_process_midi(snd_seq_event_t * ev, int direct,
                        void *private_data, int atomic, int hop)
{
      seq_midisynth_t *msynth = (seq_midisynth_t *) private_data;
      unsigned char msg[10];  /* buffer for constructing midi messages */
      snd_rawmidi_substream_t *substream;
      int res;

      snd_assert(msynth != NULL, return -EINVAL);
      substream = msynth->output_rfile.output;
      if (substream == NULL)
            return -ENODEV;
      if (ev->type == SNDRV_SEQ_EVENT_SYSEX) {  /* special case, to save space */
            if ((ev->flags & SNDRV_SEQ_EVENT_LENGTH_MASK) != SNDRV_SEQ_EVENT_LENGTH_VARIABLE) {
                  /* invalid event */
                  snd_printd("seq_midi: invalid sysex event flags = 0x%x\n", ev->flags);
                  return 0;
            }
            res = snd_seq_dump_var_event(ev, (snd_seq_dump_func_t)dump_midi, substream);
            snd_midi_event_reset_decode(msynth->parser);
            if (res < 0)
                  return res;
      } else {
            if (msynth->parser == NULL)
                  return -EIO;
            res = snd_midi_event_decode(msynth->parser, msg, sizeof(msg), ev);
            if (res < 0)
                  return res;
            if ((res = dump_midi(substream, msg, res)) < 0) {
                  snd_midi_event_reset_decode(msynth->parser);
                  return res;
            }
      }
      return 0;
}


static int snd_seq_midisynth_new(seq_midisynth_t *msynth,
                         snd_card_t *card,
                         int device,
                         int subdevice)
{
      if (snd_midi_event_new(MAX_MIDI_EVENT_BUF, &msynth->parser) < 0)
            return -ENOMEM;
      msynth->card = card;
      msynth->device = device;
      msynth->subdevice = subdevice;
      return 0;
}

/* open associated midi device for input */
static int midisynth_subscribe(void *private_data, snd_seq_port_subscribe_t *info)
{
      int err;
      seq_midisynth_t *msynth = (seq_midisynth_t *)private_data;
      snd_rawmidi_runtime_t *runtime;
      snd_rawmidi_params_t params;

      /* open midi port */
      if ((err = snd_rawmidi_kernel_open(msynth->card->number, msynth->device, msynth->subdevice, SNDRV_RAWMIDI_LFLG_INPUT, &msynth->input_rfile)) < 0) {
            snd_printd("midi input open failed!!!\n");
            return err;
      }
      runtime = msynth->input_rfile.input->runtime;
      memset(&params, 0, sizeof(params));
      params.avail_min = 1;
      params.buffer_size = input_buffer_size;
      if ((err = snd_rawmidi_input_params(msynth->input_rfile.input, &params)) < 0) {
            snd_rawmidi_kernel_release(&msynth->input_rfile);
            return err;
      }
      snd_midi_event_reset_encode(msynth->parser);
      runtime->event = snd_midi_input_event;
      runtime->private_data = msynth;
      snd_rawmidi_kernel_read(msynth->input_rfile.input, NULL, 0);
      return 0;
}

/* close associated midi device for input */
static int midisynth_unsubscribe(void *private_data, snd_seq_port_subscribe_t *info)
{
      int err;
      seq_midisynth_t *msynth = (seq_midisynth_t *)private_data;

      snd_assert(msynth->input_rfile.input != NULL, return -EINVAL);
      err = snd_rawmidi_kernel_release(&msynth->input_rfile);
      return err;
}

/* open associated midi device for output */
static int midisynth_use(void *private_data, snd_seq_port_subscribe_t *info)
{
      int err;
      seq_midisynth_t *msynth = (seq_midisynth_t *)private_data;
      snd_rawmidi_params_t params;

      /* open midi port */
      if ((err = snd_rawmidi_kernel_open(msynth->card->number, msynth->device, msynth->subdevice, SNDRV_RAWMIDI_LFLG_OUTPUT, &msynth->output_rfile)) < 0) {
            snd_printd("midi output open failed!!!\n");
            return err;
      }
      memset(&params, 0, sizeof(params));
      params.avail_min = 1;
      params.buffer_size = output_buffer_size;
      if ((err = snd_rawmidi_output_params(msynth->output_rfile.output, &params)) < 0) {
            snd_rawmidi_kernel_release(&msynth->output_rfile);
            return err;
      }
      snd_midi_event_reset_decode(msynth->parser);
      return 0;
}

/* close associated midi device for output */
static int midisynth_unuse(void *private_data, snd_seq_port_subscribe_t *info)
{
      seq_midisynth_t *msynth = (seq_midisynth_t *)private_data;
      unsigned char buf = 0xff; /* MIDI reset */

      snd_assert(msynth->output_rfile.output != NULL, return -EINVAL);
      /* sending single MIDI reset message to shut the device up */
      snd_rawmidi_kernel_write(msynth->output_rfile.output, &buf, 1);
      snd_rawmidi_drain_output(msynth->output_rfile.output);
      return snd_rawmidi_kernel_release(&msynth->output_rfile);
}

/* delete given midi synth port */
static void snd_seq_midisynth_delete(seq_midisynth_t *msynth)
{
      if (msynth == NULL)
            return;

      if (msynth->seq_client > 0) {
            /* delete port */
            snd_seq_event_port_detach(msynth->seq_client, msynth->seq_port);
      }

      if (msynth->parser)
            snd_midi_event_free(msynth->parser);
}

/* set our client name */
static int set_client_name(seq_midisynth_client_t *client, snd_card_t *card,
                     snd_rawmidi_info_t *rmidi)
{
      snd_seq_client_info_t cinfo;
      const char *name;

      memset(&cinfo, 0, sizeof(cinfo));
      cinfo.client = client->seq_client;
      cinfo.type = KERNEL_CLIENT;
      name = rmidi->name[0] ? (const char *)rmidi->name : "External MIDI";
      strlcpy(cinfo.name, name, sizeof(cinfo.name));
      return snd_seq_kernel_client_ctl(client->seq_client, SNDRV_SEQ_IOCTL_SET_CLIENT_INFO, &cinfo);
}

/* register new midi synth port */
static int
snd_seq_midisynth_register_port(snd_seq_device_t *dev)
{
      seq_midisynth_client_t *client;
      seq_midisynth_t *msynth, *ms;
      snd_seq_port_info_t port;
      snd_rawmidi_info_t info;
      int newclient = 0;
      unsigned int p, ports;
      snd_seq_client_callback_t callbacks;
      snd_seq_port_callback_t pcallbacks;
      snd_card_t *card = dev->card;
      int device = dev->device;
      unsigned int input_count = 0, output_count = 0;

      snd_assert(card != NULL && device >= 0 && device < SNDRV_RAWMIDI_DEVICES, return -EINVAL);
      info.device = device;
      info.stream = SNDRV_RAWMIDI_STREAM_OUTPUT;
      info.subdevice = 0;
      if (snd_rawmidi_info_select(card, &info) >= 0)
            output_count = info.subdevices_count;
      info.stream = SNDRV_RAWMIDI_STREAM_INPUT;
      if (snd_rawmidi_info_select(card, &info) >= 0) {
            input_count = info.subdevices_count;
      }
      ports = output_count;
      if (ports < input_count)
            ports = input_count;
      if (ports == 0)
            return -ENODEV;
      if (ports > (256 / SNDRV_RAWMIDI_DEVICES))
            ports = 256 / SNDRV_RAWMIDI_DEVICES;

      down(&register_mutex);
      client = synths[card->number];
      if (client == NULL) {
            newclient = 1;
            client = kcalloc(1, sizeof(*client), GFP_KERNEL);
            if (client == NULL) {
                  up(&register_mutex);
                  return -ENOMEM;
            }
            memset(&callbacks, 0, sizeof(callbacks));
            callbacks.private_data = client;
            callbacks.allow_input = callbacks.allow_output = 1;
            client->seq_client = snd_seq_create_kernel_client(card, 0, &callbacks);
            if (client->seq_client < 0) {
                  kfree(client);
                  up(&register_mutex);
                  return -ENOMEM;
            }
            set_client_name(client, card, &info);
      } else if (device == 0)
            set_client_name(client, card, &info); /* use the first device's name */

      msynth = kcalloc(ports, sizeof(seq_midisynth_t), GFP_KERNEL);
      if (msynth == NULL)
            goto __nomem;

      for (p = 0; p < ports; p++) {
            ms = &msynth[p];

            if (snd_seq_midisynth_new(ms, card, device, p) < 0)
                  goto __nomem;

            /* declare port */
            memset(&port, 0, sizeof(port));
            port.addr.client = client->seq_client;
            port.addr.port = device * (256 / SNDRV_RAWMIDI_DEVICES) + p;
            port.flags = SNDRV_SEQ_PORT_FLG_GIVEN_PORT;
            memset(&info, 0, sizeof(info));
            info.device = device;
            if (p < output_count)
                  info.stream = SNDRV_RAWMIDI_STREAM_OUTPUT;
            else
                  info.stream = SNDRV_RAWMIDI_STREAM_INPUT;
            info.subdevice = p;
            if (snd_rawmidi_info_select(card, &info) >= 0)
                  strcpy(port.name, info.subname);
            if (! port.name[0]) {
                  if (info.name[0]) {
                        if (ports > 1)
                              snprintf(port.name, sizeof(port.name), "%s-%d", info.name, p);
                        else
                              snprintf(port.name, sizeof(port.name), "%s", info.name);
                  } else {
                        /* last resort */
                        if (ports > 1)
                              sprintf(port.name, "MIDI %d-%d-%d", card->number, device, p);
                        else
                              sprintf(port.name, "MIDI %d-%d", card->number, device);
                  }
            }
            if ((info.flags & SNDRV_RAWMIDI_INFO_OUTPUT) && p < output_count)
                  port.capability |= SNDRV_SEQ_PORT_CAP_WRITE | SNDRV_SEQ_PORT_CAP_SYNC_WRITE | SNDRV_SEQ_PORT_CAP_SUBS_WRITE;
            if ((info.flags & SNDRV_RAWMIDI_INFO_INPUT) && p < input_count)
                  port.capability |= SNDRV_SEQ_PORT_CAP_READ | SNDRV_SEQ_PORT_CAP_SYNC_READ | SNDRV_SEQ_PORT_CAP_SUBS_READ;
            if ((port.capability & (SNDRV_SEQ_PORT_CAP_WRITE|SNDRV_SEQ_PORT_CAP_READ)) == (SNDRV_SEQ_PORT_CAP_WRITE|SNDRV_SEQ_PORT_CAP_READ) &&
                info.flags & SNDRV_RAWMIDI_INFO_DUPLEX)
                  port.capability |= SNDRV_SEQ_PORT_CAP_DUPLEX;
            port.type = SNDRV_SEQ_PORT_TYPE_MIDI_GENERIC;
            port.midi_channels = 16;
            memset(&pcallbacks, 0, sizeof(pcallbacks));
            pcallbacks.owner = THIS_MODULE;
            pcallbacks.private_data = ms;
            pcallbacks.subscribe = midisynth_subscribe;
            pcallbacks.unsubscribe = midisynth_unsubscribe;
            pcallbacks.use = midisynth_use;
            pcallbacks.unuse = midisynth_unuse;
            pcallbacks.event_input = event_process_midi;
            port.kernel = &pcallbacks;
            if (snd_seq_kernel_client_ctl(client->seq_client, SNDRV_SEQ_IOCTL_CREATE_PORT, &port)<0)
                  goto __nomem;
            ms->seq_client = client->seq_client;
            ms->seq_port = port.addr.port;
      }
      client->ports_per_device[device] = ports;
      client->ports[device] = msynth;
      client->num_ports++;
      if (newclient)
            synths[card->number] = client;
      up(&register_mutex);
      return 0;   /* success */

      __nomem:
      if (msynth != NULL) {
                  for (p = 0; p < ports; p++)
                        snd_seq_midisynth_delete(&msynth[p]);
            kfree(msynth);
      }
      if (newclient) {
            snd_seq_delete_kernel_client(client->seq_client);
            kfree(client);
      }
      up(&register_mutex);
      return -ENOMEM;
}

/* release midi synth port */
static int
snd_seq_midisynth_unregister_port(snd_seq_device_t *dev)
{
      seq_midisynth_client_t *client;
      seq_midisynth_t *msynth;
      snd_card_t *card = dev->card;
      int device = dev->device, p, ports;
      
      down(&register_mutex);
      client = synths[card->number];
      if (client == NULL || client->ports[device] == NULL) {
            up(&register_mutex);
            return -ENODEV;
      }
      ports = client->ports_per_device[device];
      client->ports_per_device[device] = 0;
      msynth = client->ports[device];
      client->ports[device] = NULL;
      snd_runtime_check(msynth != NULL || ports <= 0, goto __skip);
      for (p = 0; p < ports; p++)
            snd_seq_midisynth_delete(&msynth[p]);
      kfree(msynth);
      __skip:
      client->num_ports--;
      if (client->num_ports <= 0) {
            snd_seq_delete_kernel_client(client->seq_client);
            synths[card->number] = NULL;
            kfree(client);
      }
      up(&register_mutex);
      return 0;
}


static int __init alsa_seq_midi_init(void)
{
      static snd_seq_dev_ops_t ops = {
            snd_seq_midisynth_register_port,
            snd_seq_midisynth_unregister_port,
      };
      memset(&synths, 0, sizeof(synths));
      snd_seq_autoload_lock();
      snd_seq_device_register_driver(SNDRV_SEQ_DEV_ID_MIDISYNTH, &ops, 0);
      snd_seq_autoload_unlock();
      return 0;
}

static void __exit alsa_seq_midi_exit(void)
{
      snd_seq_device_unregister_driver(SNDRV_SEQ_DEV_ID_MIDISYNTH);
}

module_init(alsa_seq_midi_init)
module_exit(alsa_seq_midi_exit)

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