seq_ports.c

linux-2.6.15.6

	/* set port name */
	if (info->name[0])
		strlcpy(port->name, info->name, sizeof(port->name));
	
	/* set capabilities */
	port->capability = info->capability;
	
	/* get port type */
	port->type = info->type;

	/* information about supported channels/voices */
	port->midi_channels = info->midi_channels;
	port->midi_voices = info->midi_voices;
	port->synth_voices = info->synth_voices;

	/* timestamping */
	port->timestamping = (info->flags & SNDRV_SEQ_PORT_FLG_TIMESTAMP) ? 1 : 0;
	port->time_real = (info->flags & SNDRV_SEQ_PORT_FLG_TIME_REAL) ? 1 : 0;
	port->time_queue = info->time_queue;

	return 0;
}

/* get port info fields */
int snd_seq_get_port_info(client_port_t * port, snd_seq_port_info_t * info)
{
	snd_assert(port && info, return -EINVAL);

	/* get port name */
	strlcpy(info->name, port->name, sizeof(info->name));
	
	/* get capabilities */
	info->capability = port->capability;

	/* get port type */
	info->type = port->type;

	/* information about supported channels/voices */
	info->midi_channels = port->midi_channels;
	info->midi_voices = port->midi_voices;
	info->synth_voices = port->synth_voices;

	/* get subscriber counts */
	info->read_use = port->c_src.count;
	info->write_use = port->c_dest.count;
	
	/* timestamping */
	info->flags = 0;
	if (port->timestamping) {
		info->flags |= SNDRV_SEQ_PORT_FLG_TIMESTAMP;
		if (port->time_real)
			info->flags |= SNDRV_SEQ_PORT_FLG_TIME_REAL;
		info->time_queue = port->time_queue;
	}

	return 0;
}



/*
 * call callback functions (if any):
 * the callbacks are invoked only when the first (for connection) or
 * the last subscription (for disconnection) is done.  Second or later
 * subscription results in increment of counter, but no callback is
 * invoked.
 * This feature is useful if these callbacks are associated with
 * initialization or termination of devices (see seq_midi.c).
 *
 * If callback_all option is set, the callback function is invoked
 * at each connnection/disconnection. 
 */

static int subscribe_port(client_t *client, client_port_t *port, port_subs_info_t *grp,
			  snd_seq_port_subscribe_t *info, int send_ack)
{
	int err = 0;

	if (!try_module_get(port->owner))
		return -EFAULT;
	grp->count++;
	if (grp->open && (port->callback_all || grp->count == 1)) {
		err = grp->open(port->private_data, info);
		if (err < 0) {
			module_put(port->owner);
			grp->count--;
		}
	}
	if (err >= 0 && send_ack && client->type == USER_CLIENT)
		snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
						   info, SNDRV_SEQ_EVENT_PORT_SUBSCRIBED);

	return err;
}

static int unsubscribe_port(client_t *client, client_port_t *port,
			    port_subs_info_t *grp,
			    snd_seq_port_subscribe_t *info, int send_ack)
{
	int err = 0;

	if (! grp->count)
		return -EINVAL;
	grp->count--;
	if (grp->close && (port->callback_all || grp->count == 0))
		err = grp->close(port->private_data, info);
	if (send_ack && client->type == USER_CLIENT)
		snd_seq_client_notify_subscription(port->addr.client, port->addr.port,
						   info, SNDRV_SEQ_EVENT_PORT_UNSUBSCRIBED);
	module_put(port->owner);
	return err;
}



/* check if both addresses are identical */
static inline int addr_match(snd_seq_addr_t *r, snd_seq_addr_t *s)
{
	return (r->client == s->client) && (r->port == s->port);
}

/* check the two subscribe info match */
/* if flags is zero, checks only sender and destination addresses */
static int match_subs_info(snd_seq_port_subscribe_t *r,
			   snd_seq_port_subscribe_t *s)
{
	if (addr_match(&r->sender, &s->sender) &&
	    addr_match(&r->dest, &s->dest)) {
		if (r->flags && r->flags == s->flags)
			return r->queue == s->queue;
		else if (! r->flags)
			return 1;
	}
	return 0;
}


/* connect two ports */
int snd_seq_port_connect(client_t *connector,
			 client_t *src_client, client_port_t *src_port,
			 client_t *dest_client, client_port_t *dest_port,
			 snd_seq_port_subscribe_t *info)
{
	port_subs_info_t *src = &src_port->c_src;
	port_subs_info_t *dest = &dest_port->c_dest;
	subscribers_t *subs;
	struct list_head *p;
	int err, src_called = 0;
	unsigned long flags;
	int exclusive;

	subs = kzalloc(sizeof(*subs), GFP_KERNEL);
	if (! subs)
		return -ENOMEM;

	subs->info = *info;
	atomic_set(&subs->ref_count, 2);

	down_write(&src->list_mutex);
	down_write(&dest->list_mutex);

	exclusive = info->flags & SNDRV_SEQ_PORT_SUBS_EXCLUSIVE ? 1 : 0;
	err = -EBUSY;
	if (exclusive) {
		if (! list_empty(&src->list_head) || ! list_empty(&dest->list_head))
			goto __error;
	} else {
		if (src->exclusive || dest->exclusive)
			goto __error;
		/* check whether already exists */
		list_for_each(p, &src->list_head) {
			subscribers_t *s = list_entry(p, subscribers_t, src_list);
			if (match_subs_info(info, &s->info))
				goto __error;
		}
		list_for_each(p, &dest->list_head) {
			subscribers_t *s = list_entry(p, subscribers_t, dest_list);
			if (match_subs_info(info, &s->info))
				goto __error;
		}
	}

	if ((err = subscribe_port(src_client, src_port, src, info,
				  connector->number != src_client->number)) < 0)
		goto __error;
	src_called = 1;

	if ((err = subscribe_port(dest_client, dest_port, dest, info,
				  connector->number != dest_client->number)) < 0)
		goto __error;

	/* add to list */
	write_lock_irqsave(&src->list_lock, flags);
	// write_lock(&dest->list_lock); // no other lock yet
	list_add_tail(&subs->src_list, &src->list_head);
	list_add_tail(&subs->dest_list, &dest->list_head);
	// write_unlock(&dest->list_lock); // no other lock yet
	write_unlock_irqrestore(&src->list_lock, flags);

	src->exclusive = dest->exclusive = exclusive;

	up_write(&dest->list_mutex);
	up_write(&src->list_mutex);
	return 0;

 __error:
	if (src_called)
		unsubscribe_port(src_client, src_port, src, info,
				 connector->number != src_client->number);
	kfree(subs);
	up_write(&dest->list_mutex);
	up_write(&src->list_mutex);
	return err;
}


/* remove the connection */
int snd_seq_port_disconnect(client_t *connector,
			    client_t *src_client, client_port_t *src_port,
			    client_t *dest_client, client_port_t *dest_port,
			    snd_seq_port_subscribe_t *info)
{
	port_subs_info_t *src = &src_port->c_src;
	port_subs_info_t *dest = &dest_port->c_dest;
	subscribers_t *subs;
	struct list_head *p;
	int err = -ENOENT;
	unsigned long flags;

	down_write(&src->list_mutex);
	down_write(&dest->list_mutex);

	/* look for the connection */
	list_for_each(p, &src->list_head) {
		subs = list_entry(p, subscribers_t, src_list);
		if (match_subs_info(info, &subs->info)) {
			write_lock_irqsave(&src->list_lock, flags);
			// write_lock(&dest->list_lock);  // no lock yet
			list_del(&subs->src_list);
			list_del(&subs->dest_list);
			// write_unlock(&dest->list_lock);
			write_unlock_irqrestore(&src->list_lock, flags);
			src->exclusive = dest->exclusive = 0;
			unsubscribe_port(src_client, src_port, src, info,
					 connector->number != src_client->number);
			unsubscribe_port(dest_client, dest_port, dest, info,
					 connector->number != dest_client->number);
			kfree(subs);
			err = 0;
			break;
		}
	}

	up_write(&dest->list_mutex);
	up_write(&src->list_mutex);
	return err;
}


/* get matched subscriber */
subscribers_t *snd_seq_port_get_subscription(port_subs_info_t *src_grp,
					     snd_seq_addr_t *dest_addr)
{
	struct list_head *p;
	subscribers_t *s, *found = NULL;

	down_read(&src_grp->list_mutex);
	list_for_each(p, &src_grp->list_head) {
		s = list_entry(p, subscribers_t, src_list);
		if (addr_match(dest_addr, &s->info.dest)) {
			found = s;
			break;
		}
	}
	up_read(&src_grp->list_mutex);
	return found;
}

/*
 * Attach a device driver that wants to receive events from the
 * sequencer.  Returns the new port number on success.
 * A driver that wants to receive the events converted to midi, will
 * use snd_seq_midisynth_register_port().
 */
/* exported */
int snd_seq_event_port_attach(int client,
			      snd_seq_port_callback_t *pcbp,
			      int cap, int type, int midi_channels,
			      int midi_voices, char *portname)
{
	snd_seq_port_info_t portinfo;
	int  ret;

	/* Set up the port */
	memset(&portinfo, 0, sizeof(portinfo));
	portinfo.addr.client = client;
	strlcpy(portinfo.name, portname ? portname : "Unamed port",
		sizeof(portinfo.name));

	portinfo.capability = cap;
	portinfo.type = type;
	portinfo.kernel = pcbp;
	portinfo.midi_channels = midi_channels;
	portinfo.midi_voices = midi_voices;

	/* Create it */
	ret = snd_seq_kernel_client_ctl(client,
					SNDRV_SEQ_IOCTL_CREATE_PORT,
					&portinfo);

	if (ret >= 0)
		ret = portinfo.addr.port;

	return ret;
}


/*
 * Detach the driver from a port.
 */
/* exported */
int snd_seq_event_port_detach(int client, int port)
{
	snd_seq_port_info_t portinfo;
	int  err;

	memset(&portinfo, 0, sizeof(portinfo));
	portinfo.addr.client = client;
	portinfo.addr.port   = port;
	err = snd_seq_kernel_client_ctl(client,
					SNDRV_SEQ_IOCTL_DELETE_PORT,
					&portinfo);

	return err;
}