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 (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: &ev, client, port) < 0) |
84 | return; |
85 | ev.type = type; |
86 | snd_seq_kernel_client_dispatch(client: sysclient, ev: &ev, atomic: 0, hop: 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(client: sysclient, ev, atomic: 0, hop: 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(size: 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, client_index: 0, name_fmt: "System" ); |
124 | if (sysclient < 0) { |
125 | kfree(objp: port); |
126 | return sysclient; |
127 | } |
128 | |
129 | /* register timer */ |
130 | strcpy(p: port->name, q: "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(client: sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT, |
139 | arg: port); |
140 | if (err < 0) |
141 | goto error_port; |
142 | |
143 | /* register announcement port */ |
144 | strcpy(p: port->name, q: "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(client: sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT, |
152 | arg: port); |
153 | if (err < 0) |
154 | goto error_port; |
155 | announce_port = port->addr.port; |
156 | |
157 | kfree(objp: port); |
158 | return 0; |
159 | |
160 | error_port: |
161 | snd_seq_system_client_done(); |
162 | kfree(objp: 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(client: oldsysclient); |
176 | } |
177 | } |
178 | |