// SPDX-License-Identifier: GPL-2.0-or-later/* *   ALSA sequencer System services Client *   Copyright (c) 1998-1999 by Frank van de Pol <fvdpol@coil.demon.nl> */ #include <linux/init.h>#include <linux/export.h>#include <linux/slab.h>#include <sound/core.h>#include "seq_system.h"#include "seq_timer.h"#include "seq_queue.h" /* internal client that provide system services, access to timer etc. */ /* * Port "Timer" *      - send tempo /start/stop etc. events to this port to manipulate the  *        queue's timer. The queue address is specified in *	  data.queue.queue. *      - this port supports subscription. The received timer events are  *        broadcasted to all subscribed clients. The modified tempo *	  value is stored on data.queue.value. *	  The modifier client/port is not send. * * Port "Announce" *      - does not receive message *      - supports supscription. For each client or port attaching to or  *        detaching from the system an announcement is send to the subscribed *        clients. * * Idea: the subscription mechanism might also work handy for distributing  * synchronisation and timing information. In this case we would ideally have * a list of subscribers for each type of sync (time, tick), for each timing * queue. * * NOTE: the queue to be started, stopped, etc. must be specified *	 in data.queue.addr.queue field.  queue is used only for *	 scheduling, and no longer referred as affected queue. *	 They are used only for timer broadcast (see above). *							-- iwai */  /* client id of our system client */static int sysclient = -1; /* port id numbers for this client */static int announce_port = -1; /* number of subscriptions to announce port */static int announce_subscribed;  /* fill standard header data, source port & channel are filled in */static int setheader(struct snd_seq_event * ev, int client, int port){	if (announce_port < 0 || !announce_subscribed)		return -ENODEV; 	memset(ev, 0, sizeof(struct snd_seq_event)); 	ev->flags &= ~SNDRV_SEQ_EVENT_LENGTH_MASK;	ev->flags |= SNDRV_SEQ_EVENT_LENGTH_FIXED; 	ev->source.client = sysclient;	ev->source.port = announce_port;	ev->dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS; 	/* fill data */	/*ev->data.addr.queue = SNDRV_SEQ_ADDRESS_UNKNOWN;*/	ev->data.addr.client = client;	ev->data.addr.port = port; 	return 0;}  /* entry points for broadcasting system events */void snd_seq_system_broadcast(int client, int port, int type, bool atomic){	struct snd_seq_event ev;		if (setheader(&ev, client, port) < 0)		return;	ev.type = type;	snd_seq_kernel_client_dispatch(sysclient, &ev, atomic, 0);}EXPORT_SYMBOL_GPL(snd_seq_system_broadcast); /* entry points for broadcasting system events */int snd_seq_system_notify(int client, int port, struct snd_seq_event *ev,			  bool atomic){	ev->flags = SNDRV_SEQ_EVENT_LENGTH_FIXED;	ev->source.client = sysclient;	ev->source.port = announce_port;	ev->dest.client = client;	ev->dest.port = port;	return snd_seq_kernel_client_dispatch(sysclient, ev, atomic, 0);} /* call-back handler for timer events */static int event_input_timer(struct snd_seq_event * ev, int direct, void *private_data, int atomic, int hop){	return snd_seq_control_queue(ev, atomic, hop);} static int sys_announce_subscribe(void *private_data,				  struct snd_seq_port_subscribe *info){	announce_subscribed++;	return 0;} static int sys_announce_unsubscribe(void *private_data,				    struct snd_seq_port_subscribe *info){	if (snd_BUG_ON(!announce_subscribed))		return 0;	announce_subscribed--;	return 0;} /* register our internal client */int __init snd_seq_system_client_init(void){	struct snd_seq_port_callback pcallbacks;	struct snd_seq_port_info *port;	int err; 	port = kzalloc_obj(*port);	if (!port)		return -ENOMEM; 	memset(&pcallbacks, 0, sizeof(pcallbacks));	pcallbacks.owner = THIS_MODULE;	pcallbacks.event_input = event_input_timer; 	/* register client */	sysclient = snd_seq_create_kernel_client(NULL, 0, "System");	if (sysclient < 0) {		kfree(port);		return sysclient;	} 	/* register timer */	strscpy(port->name, "Timer");	port->capability = SNDRV_SEQ_PORT_CAP_WRITE; /* accept queue control */	port->capability |= SNDRV_SEQ_PORT_CAP_READ|SNDRV_SEQ_PORT_CAP_SUBS_READ; /* for broadcast */	port->kernel = &pcallbacks;	port->type = 0;	port->flags = SNDRV_SEQ_PORT_FLG_GIVEN_PORT;	port->addr.client = sysclient;	port->addr.port = SNDRV_SEQ_PORT_SYSTEM_TIMER;	err = snd_seq_kernel_client_ctl(sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT,					port);	if (err < 0)		goto error_port; 	/* register announcement port */	strscpy(port->name, "Announce");	port->capability = SNDRV_SEQ_PORT_CAP_READ|SNDRV_SEQ_PORT_CAP_SUBS_READ; /* for broadcast only */	pcallbacks.event_input = NULL;	pcallbacks.subscribe = sys_announce_subscribe;	pcallbacks.unsubscribe = sys_announce_unsubscribe;	port->kernel = &pcallbacks;	port->type = 0;	port->flags = SNDRV_SEQ_PORT_FLG_GIVEN_PORT;	port->addr.client = sysclient;	port->addr.port = SNDRV_SEQ_PORT_SYSTEM_ANNOUNCE;	err = snd_seq_kernel_client_ctl(sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT,					port);	if (err < 0)		goto error_port;	announce_port = port->addr.port; 	kfree(port);	return 0;  error_port:	snd_seq_system_client_done();	kfree(port);	return err;}  /* unregister our internal client */void snd_seq_system_client_done(void){	int oldsysclient = sysclient; 	if (oldsysclient >= 0) {		sysclient = -1;		announce_port = -1;		snd_seq_delete_kernel_client(oldsysclient);	}}