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
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