// SPDX-License-Identifier: GPL-2.0-or-later
/*
* ALSA sequencer MIDI-through client
* Copyright (c) 1999-2000 by Takashi Iwai <[email protected]>
*/
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <sound/core.h>
#include "seq_clientmgr.h"
#include <sound/initval.h>
#include <sound/asoundef.h>
/*
Sequencer MIDI-through client
This gives a simple midi-through client. All the normal input events
are redirected to output port immediately.
The routing can be done via aconnect program in alsa-utils.
Each client has a static client number 14 (= SNDRV_SEQ_CLIENT_DUMMY).
If you want to auto-load this module, you may add the following alias
in your /etc/conf.modules file.
alias snd-seq-client-14 snd-seq-dummy
The module is loaded on demand for client 14, or /proc/asound/seq/
is accessed. If you don't need this module to be loaded, alias
snd-seq-client-14 as "off". This will help modprobe.
The number of ports to be created can be specified via the module
parameter "ports". For example, to create four ports, add the
following option in a configuration file under /etc/modprobe.d/:
option snd-seq-dummy ports=4
The model option "duplex=1" enables duplex operation to the port.
In duplex mode, a pair of ports are created instead of single port,
and events are tunneled between pair-ports. For example, input to
port A is sent to output port of another port B and vice versa.
In duplex mode, each port has DUPLEX capability.
*/
MODULE_AUTHOR("Takashi Iwai <[email protected]>");
MODULE_DESCRIPTION("ALSA sequencer MIDI-through client");
MODULE_LICENSE("GPL");
MODULE_ALIAS("snd-seq-client-" __stringify(SNDRV_SEQ_CLIENT_DUMMY));
static int ports = 1;
static bool duplex;
module_param(ports, int, 0444);
MODULE_PARM_DESC(ports, "number of ports to be created");
module_param(duplex, bool, 0444);
MODULE_PARM_DESC(duplex, "create DUPLEX ports");
#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
static int ump;
module_param(ump, int, 0444);
MODULE_PARM_DESC(ump, "UMP conversion (0: no convert, 1: MIDI 1.0, 2: MIDI 2.0)");
#endif
struct snd_seq_dummy_port {
int client;
int port;
int duplex;
int connect;
};
static int my_client = -1;
/*
* event input callback - just redirect events to subscribers
*/
static int
dummy_input(struct snd_seq_event *ev, int direct, void *private_data,
int atomic, int hop)
{
struct snd_seq_dummy_port *p;
struct snd_seq_event tmpev;
p = private_data;
if (ev->source.client == SNDRV_SEQ_CLIENT_SYSTEM ||
ev->type == SNDRV_SEQ_EVENT_KERNEL_ERROR)
return 0; /* ignore system messages */
tmpev = *ev;
if (p->duplex)
tmpev.source.port = p->connect;
else
tmpev.source.port = p->port;
tmpev.dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS;
return snd_seq_kernel_client_dispatch(p->client, &tmpev, atomic, hop);
}
/*
* free_private callback
*/
static void
dummy_free(void *private_data)
{
kfree(private_data);
}
/*
* create a port
*/
static struct snd_seq_dummy_port __init *
create_port(int idx, int type)
{
struct snd_seq_port_info pinfo;
struct snd_seq_port_callback pcb;
struct snd_seq_dummy_port *rec;
rec = kzalloc(sizeof(*rec), GFP_KERNEL);
if (!rec)
return NULL;
rec->client = my_client;
rec->duplex = duplex;
rec->connect = 0;
memset(&pinfo, 0, sizeof(pinfo));
pinfo.addr.client = my_client;
if (duplex)
sprintf(pinfo.name, "Midi Through Port-%d:%c", idx,
(type ? 'B' : 'A'));
else
sprintf(pinfo.name, "Midi Through Port-%d", idx);
pinfo.capability = SNDRV_SEQ_PORT_CAP_READ | SNDRV_SEQ_PORT_CAP_SUBS_READ;
pinfo.capability |= SNDRV_SEQ_PORT_CAP_WRITE | SNDRV_SEQ_PORT_CAP_SUBS_WRITE;
if (duplex)
pinfo.capability |= SNDRV_SEQ_PORT_CAP_DUPLEX;
pinfo.direction = SNDRV_SEQ_PORT_DIR_BIDIRECTION;
pinfo.type = SNDRV_SEQ_PORT_TYPE_MIDI_GENERIC
| SNDRV_SEQ_PORT_TYPE_SOFTWARE
| SNDRV_SEQ_PORT_TYPE_PORT;
memset(&pcb, 0, sizeof(pcb));
pcb.owner = THIS_MODULE;
pcb.event_input = dummy_input;
pcb.private_free = dummy_free;
pcb.private_data = rec;
pinfo.kernel = &pcb;
if (snd_seq_kernel_client_ctl(my_client, SNDRV_SEQ_IOCTL_CREATE_PORT, &pinfo) < 0) {
kfree(rec);
return NULL;
}
rec->port = pinfo.addr.port;
return rec;
}
/*
* register client and create ports
*/
static int __init
register_client(void)
{
struct snd_seq_dummy_port *rec1, *rec2;
#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
struct snd_seq_client *client;
#endif
int i;
if (ports < 1) {
pr_err("ALSA: seq_dummy: invalid number of ports %d\n", ports);
return -EINVAL;
}
/* create client */
my_client = snd_seq_create_kernel_client(NULL, SNDRV_SEQ_CLIENT_DUMMY,
"Midi Through");
if (my_client < 0)
return my_client;
#if IS_ENABLED(CONFIG_SND_SEQ_UMP)
client = snd_seq_kernel_client_get(my_client);
if (!client)
return -EINVAL;
switch (ump) {
case 1:
client->midi_version = SNDRV_SEQ_CLIENT_UMP_MIDI_1_0;
break;
case 2:
client->midi_version = SNDRV_SEQ_CLIENT_UMP_MIDI_2_0;
break;
default:
/* don't convert events but just pass-through */
client->filter = SNDRV_SEQ_FILTER_NO_CONVERT;
break;
}
snd_seq_kernel_client_put(client);
#endif
/* create ports */
for (i = 0; i < ports; i++) {
rec1 = create_port(i, 0);
if (rec1 == NULL) {
snd_seq_delete_kernel_client(my_client);
return -ENOMEM;
}
if (duplex) {
rec2 = create_port(i, 1);
if (rec2 == NULL) {
snd_seq_delete_kernel_client(my_client);
return -ENOMEM;
}
rec1->connect = rec2->port;
rec2->connect = rec1->port;
}
}
return 0;
}
/*
* delete client if exists
*/
static void __exit
delete_client(void)
{
if (my_client >= 0)
snd_seq_delete_kernel_client(my_client);
}
/*
* Init part
*/
static int __init alsa_seq_dummy_init(void)
{
return register_client();
}
static void __exit alsa_seq_dummy_exit(void)
{
delete_client();
}
module_init(alsa_seq_dummy_init)
module_exit(alsa_seq_dummy_exit)
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