seq_system.c (4930B)
1// SPDX-License-Identifier: GPL-2.0-or-later 2/* 3 * ALSA sequencer System services Client 4 * 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 in 21 * data.queue.queue. 22 * - this port supports subscription. The received timer events are 23 * broadcasted to all subscribed clients. The modified tempo 24 * value is stored on data.queue.value. 25 * The modifier client/port is not send. 26 * 27 * Port "Announce" 28 * - does not receive message 29 * - supports supscription. For each client or port attaching to or 30 * detaching from the system an announcement is send to the subscribed 31 * clients. 32 * 33 * Idea: the subscription mechanism might also work handy for distributing 34 * synchronisation and timing information. In this case we would ideally have 35 * a list of subscribers for each type of sync (time, tick), for each timing 36 * queue. 37 * 38 * NOTE: the queue to be started, stopped, etc. must be specified 39 * in data.queue.addr.queue field. queue is used only for 40 * scheduling, and no longer referred as affected queue. 41 * They are used only for timer broadcast (see above). 42 * -- iwai 43 */ 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} 88 89/* entry points for broadcasting system events */ 90int snd_seq_system_notify(int client, int port, struct snd_seq_event *ev) 91{ 92 ev->flags = SNDRV_SEQ_EVENT_LENGTH_FIXED; 93 ev->source.client = sysclient; 94 ev->source.port = announce_port; 95 ev->dest.client = client; 96 ev->dest.port = port; 97 return snd_seq_kernel_client_dispatch(sysclient, ev, 0, 0); 98} 99 100/* call-back handler for timer events */ 101static int event_input_timer(struct snd_seq_event * ev, int direct, void *private_data, int atomic, int hop) 102{ 103 return snd_seq_control_queue(ev, atomic, hop); 104} 105 106/* register our internal client */ 107int __init snd_seq_system_client_init(void) 108{ 109 struct snd_seq_port_callback pcallbacks; 110 struct snd_seq_port_info *port; 111 int err; 112 113 port = kzalloc(sizeof(*port), GFP_KERNEL); 114 if (!port) 115 return -ENOMEM; 116 117 memset(&pcallbacks, 0, sizeof(pcallbacks)); 118 pcallbacks.owner = THIS_MODULE; 119 pcallbacks.event_input = event_input_timer; 120 121 /* register client */ 122 sysclient = snd_seq_create_kernel_client(NULL, 0, "System"); 123 if (sysclient < 0) { 124 kfree(port); 125 return sysclient; 126 } 127 128 /* register timer */ 129 strcpy(port->name, "Timer"); 130 port->capability = SNDRV_SEQ_PORT_CAP_WRITE; /* accept queue control */ 131 port->capability |= SNDRV_SEQ_PORT_CAP_READ|SNDRV_SEQ_PORT_CAP_SUBS_READ; /* for broadcast */ 132 port->kernel = &pcallbacks; 133 port->type = 0; 134 port->flags = SNDRV_SEQ_PORT_FLG_GIVEN_PORT; 135 port->addr.client = sysclient; 136 port->addr.port = SNDRV_SEQ_PORT_SYSTEM_TIMER; 137 err = snd_seq_kernel_client_ctl(sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT, 138 port); 139 if (err < 0) 140 goto error_port; 141 142 /* register announcement port */ 143 strcpy(port->name, "Announce"); 144 port->capability = SNDRV_SEQ_PORT_CAP_READ|SNDRV_SEQ_PORT_CAP_SUBS_READ; /* for broadcast only */ 145 port->kernel = NULL; 146 port->type = 0; 147 port->flags = SNDRV_SEQ_PORT_FLG_GIVEN_PORT; 148 port->addr.client = sysclient; 149 port->addr.port = SNDRV_SEQ_PORT_SYSTEM_ANNOUNCE; 150 err = snd_seq_kernel_client_ctl(sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT, 151 port); 152 if (err < 0) 153 goto error_port; 154 announce_port = port->addr.port; 155 156 kfree(port); 157 return 0; 158 159 error_port: 160 snd_seq_system_client_done(); 161 kfree(port); 162 return err; 163} 164 165 166/* unregister our internal client */ 167void snd_seq_system_client_done(void) 168{ 169 int oldsysclient = sysclient; 170 171 if (oldsysclient >= 0) { 172 sysclient = -1; 173 announce_port = -1; 174 snd_seq_delete_kernel_client(oldsysclient); 175 } 176}