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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * ALSA sequencer System services Client4 * Copyright (c) 1998-1999 by Frank van de Pol <fvdpol@coil.demon.nl>5 */6 7#include <linux/init.h>8#include <linux/export.h>9#include <linux/slab.h>10#include <sound/core.h>11#include "seq_system.h"12#include "seq_timer.h"13#include "seq_queue.h"14 15/* internal client that provide system services, access to timer etc. */16 17/*18 * Port "Timer"19 * - send tempo /start/stop etc. events to this port to manipulate the 20 * queue's timer. The queue address is specified in21 * data.queue.queue.22 * - this port supports subscription. The received timer events are 23 * broadcasted to all subscribed clients. The modified tempo24 * value is stored on data.queue.value.25 * The modifier client/port is not send.26 *27 * Port "Announce"28 * - does not receive message29 * - supports supscription. For each client or port attaching to or 30 * detaching from the system an announcement is send to the subscribed31 * clients.32 *33 * Idea: the subscription mechanism might also work handy for distributing 34 * synchronisation and timing information. In this case we would ideally have35 * a list of subscribers for each type of sync (time, tick), for each timing36 * queue.37 *38 * NOTE: the queue to be started, stopped, etc. must be specified39 * in data.queue.addr.queue field. queue is used only for40 * scheduling, and no longer referred as affected queue.41 * They are used only for timer broadcast (see above).42 * -- iwai43 */44 45 46/* client id of our system client */47static int sysclient = -1;48 49/* port id numbers for this client */50static int announce_port = -1;51 52 53 54/* fill standard header data, source port & channel are filled in */55static int setheader(struct snd_seq_event * ev, int client, int port)56{57 if (announce_port < 0)58 return -ENODEV;59 60 memset(ev, 0, sizeof(struct snd_seq_event));61 62 ev->flags &= ~SNDRV_SEQ_EVENT_LENGTH_MASK;63 ev->flags |= SNDRV_SEQ_EVENT_LENGTH_FIXED;64 65 ev->source.client = sysclient;66 ev->source.port = announce_port;67 ev->dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS;68 69 /* fill data */70 /*ev->data.addr.queue = SNDRV_SEQ_ADDRESS_UNKNOWN;*/71 ev->data.addr.client = client;72 ev->data.addr.port = port;73 74 return 0;75}76 77 78/* entry points for broadcasting system events */79void snd_seq_system_broadcast(int client, int port, int type)80{81 struct snd_seq_event ev;82 83 if (setheader(&ev, client, port) < 0)84 return;85 ev.type = type;86 snd_seq_kernel_client_dispatch(sysclient, &ev, 0, 0);87}88EXPORT_SYMBOL_GPL(snd_seq_system_broadcast);89 90/* entry points for broadcasting system events */91int snd_seq_system_notify(int client, int port, struct snd_seq_event *ev)92{93 ev->flags = SNDRV_SEQ_EVENT_LENGTH_FIXED;94 ev->source.client = sysclient;95 ev->source.port = announce_port;96 ev->dest.client = client;97 ev->dest.port = port;98 return snd_seq_kernel_client_dispatch(sysclient, ev, 0, 0);99}100 101/* call-back handler for timer events */102static int event_input_timer(struct snd_seq_event * ev, int direct, void *private_data, int atomic, int hop)103{104 return snd_seq_control_queue(ev, atomic, hop);105}106 107/* register our internal client */108int __init snd_seq_system_client_init(void)109{110 struct snd_seq_port_callback pcallbacks;111 struct snd_seq_port_info *port;112 int err;113 114 port = kzalloc(sizeof(*port), GFP_KERNEL);115 if (!port)116 return -ENOMEM;117 118 memset(&pcallbacks, 0, sizeof(pcallbacks));119 pcallbacks.owner = THIS_MODULE;120 pcallbacks.event_input = event_input_timer;121 122 /* register client */123 sysclient = snd_seq_create_kernel_client(NULL, 0, "System");124 if (sysclient < 0) {125 kfree(port);126 return sysclient;127 }128 129 /* register timer */130 strcpy(port->name, "Timer");131 port->capability = SNDRV_SEQ_PORT_CAP_WRITE; /* accept queue control */132 port->capability |= SNDRV_SEQ_PORT_CAP_READ|SNDRV_SEQ_PORT_CAP_SUBS_READ; /* for broadcast */133 port->kernel = &pcallbacks;134 port->type = 0;135 port->flags = SNDRV_SEQ_PORT_FLG_GIVEN_PORT;136 port->addr.client = sysclient;137 port->addr.port = SNDRV_SEQ_PORT_SYSTEM_TIMER;138 err = snd_seq_kernel_client_ctl(sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT,139 port);140 if (err < 0)141 goto error_port;142 143 /* register announcement port */144 strcpy(port->name, "Announce");145 port->capability = SNDRV_SEQ_PORT_CAP_READ|SNDRV_SEQ_PORT_CAP_SUBS_READ; /* for broadcast only */146 port->kernel = NULL;147 port->type = 0;148 port->flags = SNDRV_SEQ_PORT_FLG_GIVEN_PORT;149 port->addr.client = sysclient;150 port->addr.port = SNDRV_SEQ_PORT_SYSTEM_ANNOUNCE;151 err = snd_seq_kernel_client_ctl(sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT,152 port);153 if (err < 0)154 goto error_port;155 announce_port = port->addr.port;156 157 kfree(port);158 return 0;159 160 error_port:161 snd_seq_system_client_done();162 kfree(port);163 return err;164}165 166 167/* unregister our internal client */168void snd_seq_system_client_done(void)169{170 int oldsysclient = sysclient;171 172 if (oldsysclient >= 0) {173 sysclient = -1;174 announce_port = -1;175 snd_seq_delete_kernel_client(oldsysclient);176 }177}178