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}
88EXPORT_SYMBOL_GPL(snd_seq_system_broadcast);
89
90/* entry points for broadcasting system events */
91int 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 */
102static 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 */
108int __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 */
168void 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