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 */
setheader(struct snd_seq_event * ev,int client,int port)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 */
snd_seq_system_broadcast(int client,int port,int type)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 
89 /* entry points for broadcasting system events */
snd_seq_system_notify(int client,int port,struct snd_seq_event * ev)90 int 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 */
event_input_timer(struct snd_seq_event * ev,int direct,void * private_data,int atomic,int hop)101 static 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 */
snd_seq_system_client_init(void)107 int __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 */
snd_seq_system_client_done(void)167 void 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 }
177