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TOMOYO Linux Cross Reference
Linux/sound/core/seq/seq_system.c

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  1 /*
  2  *   ALSA sequencer System services Client
  3  *   Copyright (c) 1998-1999 by Frank van de Pol <fvdpol@coil.demon.nl>
  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 
 77         ev->flags &= ~SNDRV_SEQ_EVENT_LENGTH_MASK;
 78         ev->flags |= SNDRV_SEQ_EVENT_LENGTH_FIXED;
 79 
 80         ev->source.client = sysclient;
 81         ev->source.port = announce_port;
 82         ev->dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS;
 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 {
107         ev->flags = SNDRV_SEQ_EVENT_LENGTH_FIXED;
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 */
122 int __init snd_seq_system_client_init(void)
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 */
141         port->capability |= SNDRV_SEQ_PORT_CAP_READ|SNDRV_SEQ_PORT_CAP_SUBS_READ; /* for broadcast */
142         port->kernel = &pcallbacks;
143         port->type = 0;
144         port->flags = SNDRV_SEQ_PORT_FLG_GIVEN_PORT;
145         port->addr.client = sysclient;
146         port->addr.port = SNDRV_SEQ_PORT_SYSTEM_TIMER;
147         snd_seq_kernel_client_ctl(sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT, port);
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;
154         port->flags = SNDRV_SEQ_PORT_FLG_GIVEN_PORT;
155         port->addr.client = sysclient;
156         port->addr.port = SNDRV_SEQ_PORT_SYSTEM_ANNOUNCE;
157         snd_seq_kernel_client_ctl(sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT, port);
158         announce_port = port->addr.port;
159 
160         kfree(port);
161         return 0;
162 }
163 
164 
165 /* unregister our internal client */
166 void __exit snd_seq_system_client_done(void)
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 }
176 

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