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 /* number of subscriptions to announce port */ 53 static int announce_subscribed; 54 55 56 /* fill standard header data, source port & channel are filled in */ 57 static int setheader(struct snd_seq_event * ev, int client, int port) 58 { 59 if (announce_port < 0 || !announce_subscribed) 60 return -ENODEV; 61 62 memset(ev, 0, sizeof(struct snd_seq_event)); 63 64 ev->flags &= ~SNDRV_SEQ_EVENT_LENGTH_MASK; 65 ev->flags |= SNDRV_SEQ_EVENT_LENGTH_FIXED; 66 67 ev->source.client = sysclient; 68 ev->source.port = announce_port; 69 ev->dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS; 70 71 /* fill data */ 72 /*ev->data.addr.queue = SNDRV_SEQ_ADDRESS_UNKNOWN;*/ 73 ev->data.addr.client = client; 74 ev->data.addr.port = port; 75 76 return 0; 77 } 78 79 80 /* entry points for broadcasting system events */ 81 void snd_seq_system_broadcast(int client, int port, int type, bool atomic) 82 { 83 struct snd_seq_event ev; 84 85 if (setheader(&ev, client, port) < 0) 86 return; 87 ev.type = type; 88 snd_seq_kernel_client_dispatch(sysclient, &ev, atomic, 0); 89 } 90 EXPORT_SYMBOL_GPL(snd_seq_system_broadcast); 91 92 /* entry points for broadcasting system events */ 93 int snd_seq_system_notify(int client, int port, struct snd_seq_event *ev, 94 bool atomic) 95 { 96 ev->flags = SNDRV_SEQ_EVENT_LENGTH_FIXED; 97 ev->source.client = sysclient; 98 ev->source.port = announce_port; 99 ev->dest.client = client; 100 ev->dest.port = port; 101 return snd_seq_kernel_client_dispatch(sysclient, ev, atomic, 0); 102 } 103 104 /* call-back handler for timer events */ 105 static int event_input_timer(struct snd_seq_event * ev, int direct, void *private_data, int atomic, int hop) 106 { 107 return snd_seq_control_queue(ev, atomic, hop); 108 } 109 110 static int sys_announce_subscribe(void *private_data, 111 struct snd_seq_port_subscribe *info) 112 { 113 announce_subscribed++; 114 return 0; 115 } 116 117 static int sys_announce_unsubscribe(void *private_data, 118 struct snd_seq_port_subscribe *info) 119 { 120 if (snd_BUG_ON(!announce_subscribed)) 121 return 0; 122 announce_subscribed--; 123 return 0; 124 } 125 126 /* register our internal client */ 127 int __init snd_seq_system_client_init(void) 128 { 129 struct snd_seq_port_callback pcallbacks; 130 struct snd_seq_port_info *port; 131 int err; 132 133 port = kzalloc(sizeof(*port), GFP_KERNEL); 134 if (!port) 135 return -ENOMEM; 136 137 memset(&pcallbacks, 0, sizeof(pcallbacks)); 138 pcallbacks.owner = THIS_MODULE; 139 pcallbacks.event_input = event_input_timer; 140 141 /* register client */ 142 sysclient = snd_seq_create_kernel_client(NULL, 0, "System"); 143 if (sysclient < 0) { 144 kfree(port); 145 return sysclient; 146 } 147 148 /* register timer */ 149 strcpy(port->name, "Timer"); 150 port->capability = SNDRV_SEQ_PORT_CAP_WRITE; /* accept queue control */ 151 port->capability |= SNDRV_SEQ_PORT_CAP_READ|SNDRV_SEQ_PORT_CAP_SUBS_READ; /* for broadcast */ 152 port->kernel = &pcallbacks; 153 port->type = 0; 154 port->flags = SNDRV_SEQ_PORT_FLG_GIVEN_PORT; 155 port->addr.client = sysclient; 156 port->addr.port = SNDRV_SEQ_PORT_SYSTEM_TIMER; 157 err = snd_seq_kernel_client_ctl(sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT, 158 port); 159 if (err < 0) 160 goto error_port; 161 162 /* register announcement port */ 163 strcpy(port->name, "Announce"); 164 port->capability = SNDRV_SEQ_PORT_CAP_READ|SNDRV_SEQ_PORT_CAP_SUBS_READ; /* for broadcast only */ 165 pcallbacks.event_input = NULL; 166 pcallbacks.subscribe = sys_announce_subscribe; 167 pcallbacks.unsubscribe = sys_announce_unsubscribe; 168 port->kernel = &pcallbacks; 169 port->type = 0; 170 port->flags = SNDRV_SEQ_PORT_FLG_GIVEN_PORT; 171 port->addr.client = sysclient; 172 port->addr.port = SNDRV_SEQ_PORT_SYSTEM_ANNOUNCE; 173 err = snd_seq_kernel_client_ctl(sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT, 174 port); 175 if (err < 0) 176 goto error_port; 177 announce_port = port->addr.port; 178 179 kfree(port); 180 return 0; 181 182 error_port: 183 snd_seq_system_client_done(); 184 kfree(port); 185 return err; 186 } 187 188 189 /* unregister our internal client */ 190 void snd_seq_system_client_done(void) 191 { 192 int oldsysclient = sysclient; 193 194 if (oldsysclient >= 0) { 195 sysclient = -1; 196 announce_port = -1; 197 snd_seq_delete_kernel_client(oldsysclient); 198 } 199 } 200