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176 lines
4.8 KiB
176 lines
4.8 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* ALSA sequencer System services Client |
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* Copyright (c) 1998-1999 by Frank van de Pol <[email protected]> |
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*/ |
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#include <linux/init.h> |
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#include <linux/export.h> |
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#include <linux/slab.h> |
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#include <sound/core.h> |
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#include "seq_system.h" |
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#include "seq_timer.h" |
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#include "seq_queue.h" |
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/* internal client that provide system services, access to timer etc. */ |
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/* |
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* Port "Timer" |
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* - send tempo /start/stop etc. events to this port to manipulate the |
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* queue's timer. The queue address is specified in |
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* data.queue.queue. |
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* - this port supports subscription. The received timer events are |
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* broadcasted to all subscribed clients. The modified tempo |
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* value is stored on data.queue.value. |
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* The modifier client/port is not send. |
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* |
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* Port "Announce" |
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* - does not receive message |
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* - supports supscription. For each client or port attaching to or |
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* detaching from the system an announcement is send to the subscribed |
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* clients. |
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* |
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* Idea: the subscription mechanism might also work handy for distributing |
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* synchronisation and timing information. In this case we would ideally have |
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* a list of subscribers for each type of sync (time, tick), for each timing |
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* queue. |
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* |
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* NOTE: the queue to be started, stopped, etc. must be specified |
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* in data.queue.addr.queue field. queue is used only for |
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* scheduling, and no longer referred as affected queue. |
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* They are used only for timer broadcast (see above). |
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* -- iwai |
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*/ |
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/* client id of our system client */ |
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static int sysclient = -1; |
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/* port id numbers for this client */ |
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static int announce_port = -1; |
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/* fill standard header data, source port & channel are filled in */ |
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static int setheader(struct snd_seq_event * ev, int client, int port) |
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{ |
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if (announce_port < 0) |
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return -ENODEV; |
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memset(ev, 0, sizeof(struct snd_seq_event)); |
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ev->flags &= ~SNDRV_SEQ_EVENT_LENGTH_MASK; |
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ev->flags |= SNDRV_SEQ_EVENT_LENGTH_FIXED; |
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ev->source.client = sysclient; |
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ev->source.port = announce_port; |
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ev->dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS; |
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/* fill data */ |
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/*ev->data.addr.queue = SNDRV_SEQ_ADDRESS_UNKNOWN;*/ |
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ev->data.addr.client = client; |
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ev->data.addr.port = port; |
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return 0; |
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} |
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/* entry points for broadcasting system events */ |
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void snd_seq_system_broadcast(int client, int port, int type) |
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{ |
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struct snd_seq_event ev; |
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if (setheader(&ev, client, port) < 0) |
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return; |
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ev.type = type; |
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snd_seq_kernel_client_dispatch(sysclient, &ev, 0, 0); |
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} |
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/* entry points for broadcasting system events */ |
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int snd_seq_system_notify(int client, int port, struct snd_seq_event *ev) |
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{ |
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ev->flags = SNDRV_SEQ_EVENT_LENGTH_FIXED; |
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ev->source.client = sysclient; |
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ev->source.port = announce_port; |
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ev->dest.client = client; |
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ev->dest.port = port; |
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return snd_seq_kernel_client_dispatch(sysclient, ev, 0, 0); |
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} |
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/* call-back handler for timer events */ |
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static int event_input_timer(struct snd_seq_event * ev, int direct, void *private_data, int atomic, int hop) |
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{ |
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return snd_seq_control_queue(ev, atomic, hop); |
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} |
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/* register our internal client */ |
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int __init snd_seq_system_client_init(void) |
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{ |
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struct snd_seq_port_callback pcallbacks; |
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struct snd_seq_port_info *port; |
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int err; |
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port = kzalloc(sizeof(*port), GFP_KERNEL); |
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if (!port) |
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return -ENOMEM; |
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memset(&pcallbacks, 0, sizeof(pcallbacks)); |
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pcallbacks.owner = THIS_MODULE; |
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pcallbacks.event_input = event_input_timer; |
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/* register client */ |
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sysclient = snd_seq_create_kernel_client(NULL, 0, "System"); |
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if (sysclient < 0) { |
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kfree(port); |
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return sysclient; |
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} |
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/* register timer */ |
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strcpy(port->name, "Timer"); |
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port->capability = SNDRV_SEQ_PORT_CAP_WRITE; /* accept queue control */ |
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port->capability |= SNDRV_SEQ_PORT_CAP_READ|SNDRV_SEQ_PORT_CAP_SUBS_READ; /* for broadcast */ |
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port->kernel = &pcallbacks; |
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port->type = 0; |
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port->flags = SNDRV_SEQ_PORT_FLG_GIVEN_PORT; |
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port->addr.client = sysclient; |
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port->addr.port = SNDRV_SEQ_PORT_SYSTEM_TIMER; |
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err = snd_seq_kernel_client_ctl(sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT, |
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port); |
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if (err < 0) |
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goto error_port; |
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/* register announcement port */ |
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strcpy(port->name, "Announce"); |
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port->capability = SNDRV_SEQ_PORT_CAP_READ|SNDRV_SEQ_PORT_CAP_SUBS_READ; /* for broadcast only */ |
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port->kernel = NULL; |
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port->type = 0; |
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port->flags = SNDRV_SEQ_PORT_FLG_GIVEN_PORT; |
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port->addr.client = sysclient; |
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port->addr.port = SNDRV_SEQ_PORT_SYSTEM_ANNOUNCE; |
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err = snd_seq_kernel_client_ctl(sysclient, SNDRV_SEQ_IOCTL_CREATE_PORT, |
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port); |
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if (err < 0) |
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goto error_port; |
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announce_port = port->addr.port; |
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kfree(port); |
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return 0; |
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error_port: |
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snd_seq_system_client_done(); |
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kfree(port); |
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return err; |
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} |
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/* unregister our internal client */ |
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void snd_seq_system_client_done(void) |
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{ |
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int oldsysclient = sysclient; |
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if (oldsysclient >= 0) { |
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sysclient = -1; |
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announce_port = -1; |
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snd_seq_delete_kernel_client(oldsysclient); |
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} |
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}
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