// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Virtual Raw MIDI client on Sequencer
*
* Copyright (c) 2000 by Takashi Iwai <[email protected]>,
* Jaroslav Kysela <[email protected]>
*/
/*
* Virtual Raw MIDI client
*
* The virtual rawmidi client is a sequencer client which associate
* a rawmidi device file. The created rawmidi device file can be
* accessed as a normal raw midi, but its MIDI source and destination
* are arbitrary. For example, a user-client software synth connected
* to this port can be used as a normal midi device as well.
*
* The virtual rawmidi device accepts also multiple opens. Each file
* has its own input buffer, so that no conflict would occur. The drain
* of input/output buffer acts only to the local buffer.
*
*/
#include <linux/init.h>
#include <linux/wait.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <sound/core.h>
#include <sound/rawmidi.h>
#include <sound/info.h>
#include <sound/control.h>
#include <sound/minors.h>
#include <sound/seq_kernel.h>
#include <sound/seq_midi_event.h>
#include <sound/seq_virmidi.h>
MODULE_AUTHOR("Takashi Iwai <[email protected]>");
MODULE_DESCRIPTION("Virtual Raw MIDI client on Sequencer");
MODULE_LICENSE("GPL");
/*
* initialize an event record
*/
static void snd_virmidi_init_event(struct snd_virmidi *vmidi,
struct snd_seq_event *ev)
{
memset(ev, 0, sizeof(*ev));
ev->source.port = vmidi->port;
switch (vmidi->seq_mode) {
case SNDRV_VIRMIDI_SEQ_DISPATCH:
ev->dest.client = SNDRV_SEQ_ADDRESS_SUBSCRIBERS;
break;
case SNDRV_VIRMIDI_SEQ_ATTACH:
/* FIXME: source and destination are same - not good.. */
ev->dest.client = vmidi->client;
ev->dest.port = vmidi->port;
break;
}
ev->type = SNDRV_SEQ_EVENT_NONE;
}
/*
* decode input event and put to read buffer of each opened file
*/
/* callback for snd_seq_dump_var_event(), bridging to snd_rawmidi_receive() */
static int dump_to_rawmidi(void *ptr, void *buf, int count)
{
return snd_rawmidi_receive(ptr, buf, count);
}
static int snd_virmidi_dev_receive_event(struct snd_virmidi_dev *rdev,
struct snd_seq_event *ev,
bool atomic)
{
struct snd_virmidi *vmidi;
unsigned char msg[4];
int len;
if (atomic)
read_lock(&rdev->filelist_lock);
else
down_read(&rdev->filelist_sem);
list_for_each_entry(vmidi, &rdev->filelist, list) {
if (!READ_ONCE(vmidi->trigger))
continue;
if (ev->type == SNDRV_SEQ_EVENT_SYSEX) {
if ((ev->flags & SNDRV_SEQ_EVENT_LENGTH_MASK) != SNDRV_SEQ_EVENT_LENGTH_VARIABLE)
continue;
snd_seq_dump_var_event(ev, dump_to_rawmidi, vmidi->substream);
snd_midi_event_reset_decode(vmidi->parser);
} else {
len = snd_midi_event_decode(vmidi->parser, msg, sizeof(msg), ev);
if (len > 0)
snd_rawmidi_receive(vmidi->substream, msg, len);
}
}
if (atomic)
read_unlock(&rdev->filelist_lock);
else
up_read(&rdev->filelist_sem);
return 0;
}
/*
* event handler of virmidi port
*/
static int snd_virmidi_event_input(struct snd_seq_event *ev, int direct,
void *private_data, int atomic, int hop)
{
struct snd_virmidi_dev *rdev;
rdev = private_data;
if (!(rdev->flags & SNDRV_VIRMIDI_USE))
return 0; /* ignored */
return snd_virmidi_dev_receive_event(rdev, ev, atomic);
}
/*
* trigger rawmidi stream for input
*/
static void snd_virmidi_input_trigger(struct snd_rawmidi_substream *substream, int up)
{
struct snd_virmidi *vmidi = substream->runtime->private_data;
WRITE_ONCE(vmidi->trigger, !!up);
}
/* process rawmidi bytes and send events;
* we need no lock here for vmidi->event since it's handled only in this work
*/
static void snd_vmidi_output_work(struct work_struct *work)
{
struct snd_virmidi *vmidi;
struct snd_rawmidi_substream *substream;
unsigned char input;
int ret;
vmidi = container_of(work, struct snd_virmidi, output_work);
substream = vmidi->substream;
/* discard the outputs in dispatch mode unless subscribed */
if (vmidi->seq_mode == SNDRV_VIRMIDI_SEQ_DISPATCH &&
!(vmidi->rdev->flags & SNDRV_VIRMIDI_SUBSCRIBE)) {
snd_rawmidi_proceed(substream);
return;
}
while (READ_ONCE(vmidi->trigger)) {
if (snd_rawmidi_transmit(substream, &input, 1) != 1)
break;
if (!snd_midi_event_encode_byte(vmidi->parser, input,
&vmidi->event))
continue;
if (vmidi->event.type != SNDRV_SEQ_EVENT_NONE) {
ret = snd_seq_kernel_client_dispatch(vmidi->client,
&vmidi->event,
false, 0);
vmidi->event.type = SNDRV_SEQ_EVENT_NONE;
if (ret < 0)
break;
}
/* rawmidi input might be huge, allow to have a break */
cond_resched();
}
}
/*
* trigger rawmidi stream for output
*/
static void snd_virmidi_output_trigger(struct snd_rawmidi_substream *substream, int up)
{
struct snd_virmidi *vmidi = substream->runtime->private_data;
WRITE_ONCE(vmidi->trigger, !!up);
if (up)
queue_work(system_highpri_wq, &vmidi->output_work);
}
/*
* open rawmidi handle for input
*/
static int snd_virmidi_input_open(struct snd_rawmidi_substream *substream)
{
struct snd_virmidi_dev *rdev = substream->rmidi->private_data;
struct snd_rawmidi_runtime *runtime = substream->runtime;
struct snd_virmidi *vmidi;
vmidi = kzalloc(sizeof(*vmidi), GFP_KERNEL);
if (vmidi == NULL)
return -ENOMEM;
vmidi->substream = substream;
if (snd_midi_event_new(0, &vmidi->parser) < 0) {
kfree(vmidi);
return -ENOMEM;
}
vmidi->seq_mode = rdev->seq_mode;
vmidi->client = rdev->client;
vmidi->port = rdev->port;
runtime->private_data = vmidi;
scoped_guard(rwsem_write, &rdev->filelist_sem) {
guard(write_lock_irq)(&rdev->filelist_lock);
list_add_tail(&vmidi->list, &rdev->filelist);
}
vmidi->rdev = rdev;
return 0;
}
/*
* open rawmidi handle for output
*/
static int snd_virmidi_output_open(struct snd_rawmidi_substream *substream)
{
struct snd_virmidi_dev *rdev = substream->rmidi->private_data;
struct snd_rawmidi_runtime *runtime = substream->runtime;
struct snd_virmidi *vmidi;
vmidi = kzalloc(sizeof(*vmidi), GFP_KERNEL);
if (vmidi == NULL)
return -ENOMEM;
vmidi->substream = substream;
if (snd_midi_event_new(MAX_MIDI_EVENT_BUF, &vmidi->parser) < 0) {
kfree(vmidi);
return -ENOMEM;
}
vmidi->seq_mode = rdev->seq_mode;
vmidi->client = rdev->client;
vmidi->port = rdev->port;
snd_virmidi_init_event(vmidi, &vmidi->event);
vmidi->rdev = rdev;
INIT_WORK(&vmidi->output_work, snd_vmidi_output_work);
runtime->private_data = vmidi;
return 0;
}
/*
* close rawmidi handle for input
*/
static int snd_virmidi_input_close(struct snd_rawmidi_substream *substream)
{
struct snd_virmidi_dev *rdev = substream->rmidi->private_data;
struct snd_virmidi *vmidi = substream->runtime->private_data;
scoped_guard(rwsem_write, &rdev->filelist_sem) {
guard(write_lock_irq)(&rdev->filelist_lock);
list_del(&vmidi->list);
}
snd_midi_event_free(vmidi->parser);
substream->runtime->private_data = NULL;
kfree(vmidi);
return 0;
}
/*
* close rawmidi handle for output
*/
static int snd_virmidi_output_close(struct snd_rawmidi_substream *substream)
{
struct snd_virmidi *vmidi = substream->runtime->private_data;
WRITE_ONCE(vmidi->trigger, false); /* to be sure */
cancel_work_sync(&vmidi->output_work);
snd_midi_event_free(vmidi->parser);
substream->runtime->private_data = NULL;
kfree(vmidi);
return 0;
}
/*
* drain output work queue
*/
static void snd_virmidi_output_drain(struct snd_rawmidi_substream *substream)
{
struct snd_virmidi *vmidi = substream->runtime->private_data;
flush_work(&vmidi->output_work);
}
/*
* subscribe callback - allow output to rawmidi device
*/
static int snd_virmidi_subscribe(void *private_data,
struct snd_seq_port_subscribe *info)
{
struct snd_virmidi_dev *rdev;
rdev = private_data;
if (!try_module_get(rdev->card->module))
return -EFAULT;
rdev->flags |= SNDRV_VIRMIDI_SUBSCRIBE;
return 0;
}
/*
* unsubscribe callback - disallow output to rawmidi device
*/
static int snd_virmidi_unsubscribe(void *private_data,
struct snd_seq_port_subscribe *info)
{
struct snd_virmidi_dev *rdev;
rdev = private_data;
rdev->flags &= ~SNDRV_VIRMIDI_SUBSCRIBE;
module_put(rdev->card->module);
return 0;
}
/*
* use callback - allow input to rawmidi device
*/
static int snd_virmidi_use(void *private_data,
struct snd_seq_port_subscribe *info)
{
struct snd_virmidi_dev *rdev;
rdev = private_data;
if (!try_module_get(rdev->card->module))
return -EFAULT;
rdev->flags |= SNDRV_VIRMIDI_USE;
return 0;
}
/*
* unuse callback - disallow input to rawmidi device
*/
static int snd_virmidi_unuse(void *private_data,
struct snd_seq_port_subscribe *info)
{
struct snd_virmidi_dev *rdev;
rdev = private_data;
rdev->flags &= ~SNDRV_VIRMIDI_USE;
module_put(rdev->card->module);
return 0;
}
/*
* Register functions
*/
static const struct snd_rawmidi_ops snd_virmidi_input_ops = {
.open = snd_virmidi_input_open,
.close = snd_virmidi_input_close,
.trigger = snd_virmidi_input_trigger,
};
static const struct snd_rawmidi_ops snd_virmidi_output_ops = {
.open = snd_virmidi_output_open,
.close = snd_virmidi_output_close,
.trigger = snd_virmidi_output_trigger,
.drain = snd_virmidi_output_drain,
};
/*
* create a sequencer client and a port
*/
static int snd_virmidi_dev_attach_seq(struct snd_virmidi_dev *rdev)
{
int client;
struct snd_seq_port_callback pcallbacks;
struct snd_seq_port_info *pinfo __free(kfree) = NULL;
int err;
if (rdev->client >= 0)
return 0;
pinfo = kzalloc(sizeof(*pinfo), GFP_KERNEL);
if (!pinfo)
return -ENOMEM;
client = snd_seq_create_kernel_client(rdev->card, rdev->device,
"%s %d-%d", rdev->rmidi->name,
rdev->card->number,
rdev->device);
if (client < 0)
return client;
rdev->client = client;
/* create a port */
pinfo->addr.client = client;
sprintf(pinfo->name, "VirMIDI %d-%d", rdev->card->number, rdev->device);
/* set all capabilities */
pinfo->capability |= SNDRV_SEQ_PORT_CAP_WRITE | SNDRV_SEQ_PORT_CAP_SYNC_WRITE | SNDRV_SEQ_PORT_CAP_SUBS_WRITE;
pinfo->capability |= SNDRV_SEQ_PORT_CAP_READ | SNDRV_SEQ_PORT_CAP_SYNC_READ | SNDRV_SEQ_PORT_CAP_SUBS_READ;
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;
pinfo->midi_channels = 16;
memset(&pcallbacks, 0, sizeof(pcallbacks));
pcallbacks.owner = THIS_MODULE;
pcallbacks.private_data = rdev;
pcallbacks.subscribe = snd_virmidi_subscribe;
pcallbacks.unsubscribe = snd_virmidi_unsubscribe;
pcallbacks.use = snd_virmidi_use;
pcallbacks.unuse = snd_virmidi_unuse;
pcallbacks.event_input = snd_virmidi_event_input;
pinfo->kernel = &pcallbacks;
err = snd_seq_kernel_client_ctl(client, SNDRV_SEQ_IOCTL_CREATE_PORT, pinfo);
if (err < 0) {
snd_seq_delete_kernel_client(client);
rdev->client = -1;
return err;
}
rdev->port = pinfo->addr.port;
return 0; /* success */
}
/*
* release the sequencer client
*/
static void snd_virmidi_dev_detach_seq(struct snd_virmidi_dev *rdev)
{
if (rdev->client >= 0) {
snd_seq_delete_kernel_client(rdev->client);
rdev->client = -1;
}
}
/*
* register the device
*/
static int snd_virmidi_dev_register(struct snd_rawmidi *rmidi)
{
struct snd_virmidi_dev *rdev = rmidi->private_data;
int err;
switch (rdev->seq_mode) {
case SNDRV_VIRMIDI_SEQ_DISPATCH:
err = snd_virmidi_dev_attach_seq(rdev);
if (err < 0)
return err;
break;
case SNDRV_VIRMIDI_SEQ_ATTACH:
if (rdev->client == 0)
return -EINVAL;
/* should check presence of port more strictly.. */
break;
default:
pr_err("ALSA: seq_virmidi: seq_mode is not set: %d\n", rdev->seq_mode);
return -EINVAL;
}
return 0;
}
/*
* unregister the device
*/
static int snd_virmidi_dev_unregister(struct snd_rawmidi *rmidi)
{
struct snd_virmidi_dev *rdev = rmidi->private_data;
if (rdev->seq_mode == SNDRV_VIRMIDI_SEQ_DISPATCH)
snd_virmidi_dev_detach_seq(rdev);
return 0;
}
/*
*
*/
static const struct snd_rawmidi_global_ops snd_virmidi_global_ops = {
.dev_register = snd_virmidi_dev_register,
.dev_unregister = snd_virmidi_dev_unregister,
};
/*
* free device
*/
static void snd_virmidi_free(struct snd_rawmidi *rmidi)
{
struct snd_virmidi_dev *rdev = rmidi->private_data;
kfree(rdev);
}
/*
* create a new device
*
*/
/* exported */
int snd_virmidi_new(struct snd_card *card, int device, struct snd_rawmidi **rrmidi)
{
struct snd_rawmidi *rmidi;
struct snd_virmidi_dev *rdev;
int err;
*rrmidi = NULL;
err = snd_rawmidi_new(card, "VirMidi", device,
16, /* may be configurable */
16, /* may be configurable */
&rmidi);
if (err < 0)
return err;
strcpy(rmidi->name, rmidi->id);
rdev = kzalloc(sizeof(*rdev), GFP_KERNEL);
if (rdev == NULL) {
snd_device_free(card, rmidi);
return -ENOMEM;
}
rdev->card = card;
rdev->rmidi = rmidi;
rdev->device = device;
rdev->client = -1;
init_rwsem(&rdev->filelist_sem);
rwlock_init(&rdev->filelist_lock);
INIT_LIST_HEAD(&rdev->filelist);
rdev->seq_mode = SNDRV_VIRMIDI_SEQ_DISPATCH;
rmidi->private_data = rdev;
rmidi->private_free = snd_virmidi_free;
rmidi->ops = &snd_virmidi_global_ops;
snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_INPUT, &snd_virmidi_input_ops);
snd_rawmidi_set_ops(rmidi, SNDRV_RAWMIDI_STREAM_OUTPUT, &snd_virmidi_output_ops);
rmidi->info_flags = SNDRV_RAWMIDI_INFO_INPUT |
SNDRV_RAWMIDI_INFO_OUTPUT |
SNDRV_RAWMIDI_INFO_DUPLEX;
*rrmidi = rmidi;
return 0;
}
EXPORT_SYMBOL(snd_virmidi_new);
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