Linux Kernel  3.7.1
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seq_system.c
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1 /*
2  * ALSA sequencer System services Client
3  * Copyright (c) 1998-1999 by Frank van de Pol <[email protected]>
4  *
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19  *
20  */
21 
22 #include <linux/init.h>
23 #include <linux/export.h>
24 #include <linux/slab.h>
25 #include <sound/core.h>
26 #include "seq_system.h"
27 #include "seq_timer.h"
28 #include "seq_queue.h"
29 
30 /* internal client that provide system services, access to timer etc. */
31 
32 /*
33  * Port "Timer"
34  * - send tempo /start/stop etc. events to this port to manipulate the
35  * queue's timer. The queue address is specified in
36  * data.queue.queue.
37  * - this port supports subscription. The received timer events are
38  * broadcasted to all subscribed clients. The modified tempo
39  * value is stored on data.queue.value.
40  * The modifier client/port is not send.
41  *
42  * Port "Announce"
43  * - does not receive message
44  * - supports supscription. For each client or port attaching to or
45  * detaching from the system an announcement is send to the subscribed
46  * clients.
47  *
48  * Idea: the subscription mechanism might also work handy for distributing
49  * synchronisation and timing information. In this case we would ideally have
50  * a list of subscribers for each type of sync (time, tick), for each timing
51  * queue.
52  *
53  * NOTE: the queue to be started, stopped, etc. must be specified
54  * in data.queue.addr.queue field. queue is used only for
55  * scheduling, and no longer referred as affected queue.
56  * They are used only for timer broadcast (see above).
57  * -- iwai
58  */
59 
60 
61 /* client id of our system client */
62 static int sysclient = -1;
63 
64 /* port id numbers for this client */
65 static int announce_port = -1;
66 
67 
68 
69 /* fill standard header data, source port & channel are filled in */
70 static int setheader(struct snd_seq_event * ev, int client, int port)
71 {
72  if (announce_port < 0)
73  return -ENODEV;
74 
75  memset(ev, 0, sizeof(struct snd_seq_event));
76 
79 
80  ev->source.client = sysclient;
81  ev->source.port = announce_port;
83 
84  /* fill data */
85  /*ev->data.addr.queue = SNDRV_SEQ_ADDRESS_UNKNOWN;*/
86  ev->data.addr.client = client;
87  ev->data.addr.port = port;
88 
89  return 0;
90 }
91 
92 
93 /* entry points for broadcasting system events */
94 void snd_seq_system_broadcast(int client, int port, int type)
95 {
96  struct snd_seq_event ev;
97 
98  if (setheader(&ev, client, port) < 0)
99  return;
100  ev.type = type;
101  snd_seq_kernel_client_dispatch(sysclient, &ev, 0, 0);
102 }
103 
104 /* entry points for broadcasting system events */
105 int snd_seq_system_notify(int client, int port, struct snd_seq_event *ev)
106 {
108  ev->source.client = sysclient;
109  ev->source.port = announce_port;
110  ev->dest.client = client;
111  ev->dest.port = port;
112  return snd_seq_kernel_client_dispatch(sysclient, ev, 0, 0);
113 }
114 
115 /* call-back handler for timer events */
116 static int event_input_timer(struct snd_seq_event * ev, int direct, void *private_data, int atomic, int hop)
117 {
118  return snd_seq_control_queue(ev, atomic, hop);
119 }
120 
121 /* register our internal client */
123 {
124  struct snd_seq_port_callback pcallbacks;
125  struct snd_seq_port_info *port;
126 
127  port = kzalloc(sizeof(*port), GFP_KERNEL);
128  if (!port)
129  return -ENOMEM;
130 
131  memset(&pcallbacks, 0, sizeof(pcallbacks));
132  pcallbacks.owner = THIS_MODULE;
133  pcallbacks.event_input = event_input_timer;
134 
135  /* register client */
136  sysclient = snd_seq_create_kernel_client(NULL, 0, "System");
137 
138  /* register timer */
139  strcpy(port->name, "Timer");
140  port->capability = SNDRV_SEQ_PORT_CAP_WRITE; /* accept queue control */
142  port->kernel = &pcallbacks;
143  port->type = 0;
145  port->addr.client = sysclient;
146  port->addr.port = SNDRV_SEQ_PORT_SYSTEM_TIMER;
148 
149  /* register announcement port */
150  strcpy(port->name, "Announce");
151  port->capability = SNDRV_SEQ_PORT_CAP_READ|SNDRV_SEQ_PORT_CAP_SUBS_READ; /* for broadcast only */
152  port->kernel = NULL;
153  port->type = 0;
155  port->addr.client = sysclient;
158  announce_port = port->addr.port;
159 
160  kfree(port);
161  return 0;
162 }
163 
164 
165 /* unregister our internal client */
167 {
168  int oldsysclient = sysclient;
169 
170  if (oldsysclient >= 0) {
171  sysclient = -1;
172  announce_port = -1;
173  snd_seq_delete_kernel_client(oldsysclient);
174  }
175 }