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 */ 47 static int sysclient = -1; 48 49 /* port id numbers for this client */ 50 static int announce_port = -1; 51 52 53 54 /* fill standard header data, source port & channel are filled in */ 55 static 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 */ 79 void 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 EXPORT_SYMBOL_GPL(snd_seq_system_broadcast); 89 90 /* entry points for broadcasting system events */ 91 int 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 */ 102 static 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 */ 108 int __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 */ 168 void 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