audio: add "dbus" audio backend

Add a new -audio backend that accepts D-Bus clients/listeners to handle
playback & recording, to be exported via the -display dbus.

Example usage:
-audiodev dbus,in.mixing-engine=off,out.mixing-engine=off,id=dbus
-display dbus,audiodev=dbus

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 654 insertions, 0 deletions

diff --git a/audio/dbusaudio.c b/audio/dbusaudio.c
new file mode 100644
index 0000000000..f178b47dee
--- /dev/null
+++ b/audio/dbusaudio.c
@@ -0,0 +1,654 @@
+/*
+ * QEMU DBus audio
+ *
+ * Copyright (c) 2021 Red Hat, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/error-report.h"
+#include "qemu/host-utils.h"
+#include "qemu/module.h"
+#include "qemu/timer.h"
+#include "qemu/dbus.h"
+
+#include <gio/gunixfdlist.h>
+#include "ui/dbus-display1.h"
+
+#define AUDIO_CAP "dbus"
+#include "audio.h"
+#include "audio_int.h"
+#include "trace.h"
+
+#define DBUS_DISPLAY1_AUDIO_PATH DBUS_DISPLAY1_ROOT "/Audio"
+
+#define DBUS_AUDIO_NSAMPLES 1024 /* could be configured? */
+
+typedef struct DBusAudio {
+    GDBusObjectManagerServer *server;
+    GDBusObjectSkeleton *audio;
+    QemuDBusDisplay1Audio *iface;
+    GHashTable *out_listeners;
+    GHashTable *in_listeners;
+} DBusAudio;
+
+typedef struct DBusVoiceOut {
+    HWVoiceOut hw;
+    bool enabled;
+    RateCtl rate;
+
+    void *buf;
+    size_t buf_pos;
+    size_t buf_size;
+
+    bool has_volume;
+    Volume volume;
+} DBusVoiceOut;
+
+typedef struct DBusVoiceIn {
+    HWVoiceIn hw;
+    bool enabled;
+    RateCtl rate;
+
+    bool has_volume;
+    Volume volume;
+} DBusVoiceIn;
+
+static void *dbus_get_buffer_out(HWVoiceOut *hw, size_t *size)
+{
+    DBusVoiceOut *vo = container_of(hw, DBusVoiceOut, hw);
+
+    if (!vo->buf) {
+        vo->buf_size = hw->samples * hw->info.bytes_per_frame;
+        vo->buf = g_malloc(vo->buf_size);
+        vo->buf_pos = 0;
+    }
+
+    *size = MIN(vo->buf_size - vo->buf_pos, *size);
+    *size = audio_rate_get_bytes(&hw->info, &vo->rate, *size);
+
+    return vo->buf + vo->buf_pos;
+
+}
+
+static size_t dbus_put_buffer_out(HWVoiceOut *hw, void *buf, size_t size)
+{
+    DBusAudio *da = (DBusAudio *)hw->s->drv_opaque;
+    DBusVoiceOut *vo = container_of(hw, DBusVoiceOut, hw);
+    GHashTableIter iter;
+    QemuDBusDisplay1AudioOutListener *listener = NULL;
+    g_autoptr(GBytes) bytes = NULL;
+    g_autoptr(GVariant) v_data = NULL;
+
+    assert(buf == vo->buf + vo->buf_pos && vo->buf_pos + size <= vo->buf_size);
+    vo->buf_pos += size;
+
+    trace_dbus_audio_put_buffer_out(size);
+
+    if (vo->buf_pos < vo->buf_size) {
+        return size;
+    }
+
+    bytes = g_bytes_new_take(g_steal_pointer(&vo->buf), vo->buf_size);
+    v_data = g_variant_new_from_bytes(G_VARIANT_TYPE("ay"), bytes, TRUE);
+    g_variant_ref_sink(v_data);
+
+    g_hash_table_iter_init(&iter, da->out_listeners);
+    while (g_hash_table_iter_next(&iter, NULL, (void **)&listener)) {
+        qemu_dbus_display1_audio_out_listener_call_write(
+            listener,
+            (uintptr_t)hw,
+            v_data,
+            G_DBUS_CALL_FLAGS_NONE, -1, NULL, NULL, NULL);
+    }
+
+    return size;
+}
+
+#ifdef HOST_WORDS_BIGENDIAN
+#define AUDIO_HOST_BE TRUE
+#else
+#define AUDIO_HOST_BE FALSE
+#endif
+
+static void
+dbus_init_out_listener(QemuDBusDisplay1AudioOutListener *listener,
+                       HWVoiceOut *hw)
+{
+    qemu_dbus_display1_audio_out_listener_call_init(
+        listener,
+        (uintptr_t)hw,
+        hw->info.bits,
+        hw->info.is_signed,
+        hw->info.is_float,
+        hw->info.freq,
+        hw->info.nchannels,
+        hw->info.bytes_per_frame,
+        hw->info.bytes_per_second,
+        hw->info.swap_endianness ? !AUDIO_HOST_BE : AUDIO_HOST_BE,
+        G_DBUS_CALL_FLAGS_NONE, -1, NULL, NULL, NULL);
+}
+
+static int
+dbus_init_out(HWVoiceOut *hw, struct audsettings *as, void *drv_opaque)
+{
+    DBusAudio *da = (DBusAudio *)hw->s->drv_opaque;
+    DBusVoiceOut *vo = container_of(hw, DBusVoiceOut, hw);
+    GHashTableIter iter;
+    QemuDBusDisplay1AudioOutListener *listener = NULL;
+
+    audio_pcm_init_info(&hw->info, as);
+    hw->samples = DBUS_AUDIO_NSAMPLES;
+    audio_rate_start(&vo->rate);
+
+    g_hash_table_iter_init(&iter, da->out_listeners);
+    while (g_hash_table_iter_next(&iter, NULL, (void **)&listener)) {
+        dbus_init_out_listener(listener, hw);
+    }
+    return 0;
+}
+
+static void
+dbus_fini_out(HWVoiceOut *hw)
+{
+    DBusAudio *da = (DBusAudio *)hw->s->drv_opaque;
+    DBusVoiceOut *vo = container_of(hw, DBusVoiceOut, hw);
+    GHashTableIter iter;
+    QemuDBusDisplay1AudioOutListener *listener = NULL;
+
+    g_hash_table_iter_init(&iter, da->out_listeners);
+    while (g_hash_table_iter_next(&iter, NULL, (void **)&listener)) {
+        qemu_dbus_display1_audio_out_listener_call_fini(
+            listener,
+            (uintptr_t)hw,
+            G_DBUS_CALL_FLAGS_NONE, -1, NULL, NULL, NULL);
+    }
+
+    g_clear_pointer(&vo->buf, g_free);
+}
+
+static void
+dbus_enable_out(HWVoiceOut *hw, bool enable)
+{
+    DBusAudio *da = (DBusAudio *)hw->s->drv_opaque;
+    DBusVoiceOut *vo = container_of(hw, DBusVoiceOut, hw);
+    GHashTableIter iter;
+    QemuDBusDisplay1AudioOutListener *listener = NULL;
+
+    vo->enabled = enable;
+    if (enable) {
+        audio_rate_start(&vo->rate);
+    }
+
+    g_hash_table_iter_init(&iter, da->out_listeners);
+    while (g_hash_table_iter_next(&iter, NULL, (void **)&listener)) {
+        qemu_dbus_display1_audio_out_listener_call_set_enabled(
+            listener, (uintptr_t)hw, enable,
+            G_DBUS_CALL_FLAGS_NONE, -1, NULL, NULL, NULL);
+    }
+}
+
+static void
+dbus_volume_out_listener(HWVoiceOut *hw,
+                         QemuDBusDisplay1AudioOutListener *listener)
+{
+    DBusVoiceOut *vo = container_of(hw, DBusVoiceOut, hw);
+    Volume *vol = &vo->volume;
+    g_autoptr(GBytes) bytes = NULL;
+    GVariant *v_vol = NULL;
+
+    if (!vo->has_volume) {
+        return;
+    }
+
+    assert(vol->channels < sizeof(vol->vol));
+    bytes = g_bytes_new(vol->vol, vol->channels);
+    v_vol = g_variant_new_from_bytes(G_VARIANT_TYPE("ay"), bytes, TRUE);
+    qemu_dbus_display1_audio_out_listener_call_set_volume(
+        listener, (uintptr_t)hw, vol->mute, v_vol,
+        G_DBUS_CALL_FLAGS_NONE, -1, NULL, NULL, NULL);
+}
+
+static void
+dbus_volume_out(HWVoiceOut *hw, Volume *vol)
+{
+    DBusAudio *da = (DBusAudio *)hw->s->drv_opaque;
+    DBusVoiceOut *vo = container_of(hw, DBusVoiceOut, hw);
+    GHashTableIter iter;
+    QemuDBusDisplay1AudioOutListener *listener = NULL;
+
+    vo->has_volume = true;
+    vo->volume = *vol;
+
+    g_hash_table_iter_init(&iter, da->out_listeners);
+    while (g_hash_table_iter_next(&iter, NULL, (void **)&listener)) {
+        dbus_volume_out_listener(hw, listener);
+    }
+}
+
+static void
+dbus_init_in_listener(QemuDBusDisplay1AudioInListener *listener, HWVoiceIn *hw)
+{
+    qemu_dbus_display1_audio_in_listener_call_init(
+        listener,
+        (uintptr_t)hw,
+        hw->info.bits,
+        hw->info.is_signed,
+        hw->info.is_float,
+        hw->info.freq,
+        hw->info.nchannels,
+        hw->info.bytes_per_frame,
+        hw->info.bytes_per_second,
+        hw->info.swap_endianness ? !AUDIO_HOST_BE : AUDIO_HOST_BE,
+        G_DBUS_CALL_FLAGS_NONE, -1, NULL, NULL, NULL);
+}
+
+static int
+dbus_init_in(HWVoiceIn *hw, struct audsettings *as, void *drv_opaque)
+{
+    DBusAudio *da = (DBusAudio *)hw->s->drv_opaque;
+    DBusVoiceIn *vo = container_of(hw, DBusVoiceIn, hw);
+    GHashTableIter iter;
+    QemuDBusDisplay1AudioInListener *listener = NULL;
+
+    audio_pcm_init_info(&hw->info, as);
+    hw->samples = DBUS_AUDIO_NSAMPLES;
+    audio_rate_start(&vo->rate);
+
+    g_hash_table_iter_init(&iter, da->in_listeners);
+    while (g_hash_table_iter_next(&iter, NULL, (void **)&listener)) {
+        dbus_init_in_listener(listener, hw);
+    }
+    return 0;
+}
+
+static void
+dbus_fini_in(HWVoiceIn *hw)
+{
+    DBusAudio *da = (DBusAudio *)hw->s->drv_opaque;
+    GHashTableIter iter;
+    QemuDBusDisplay1AudioInListener *listener = NULL;
+
+    g_hash_table_iter_init(&iter, da->in_listeners);
+    while (g_hash_table_iter_next(&iter, NULL, (void **)&listener)) {
+        qemu_dbus_display1_audio_in_listener_call_fini(
+            listener,
+            (uintptr_t)hw,
+            G_DBUS_CALL_FLAGS_NONE, -1, NULL, NULL, NULL);
+    }
+}
+
+static void
+dbus_volume_in_listener(HWVoiceIn *hw,
+                         QemuDBusDisplay1AudioInListener *listener)
+{
+    DBusVoiceIn *vo = container_of(hw, DBusVoiceIn, hw);
+    Volume *vol = &vo->volume;
+    g_autoptr(GBytes) bytes = NULL;
+    GVariant *v_vol = NULL;
+
+    if (!vo->has_volume) {
+        return;
+    }
+
+    assert(vol->channels < sizeof(vol->vol));
+    bytes = g_bytes_new(vol->vol, vol->channels);
+    v_vol = g_variant_new_from_bytes(G_VARIANT_TYPE("ay"), bytes, TRUE);
+    qemu_dbus_display1_audio_in_listener_call_set_volume(
+        listener, (uintptr_t)hw, vol->mute, v_vol,
+        G_DBUS_CALL_FLAGS_NONE, -1, NULL, NULL, NULL);
+}
+
+static void
+dbus_volume_in(HWVoiceIn *hw, Volume *vol)
+{
+    DBusAudio *da = (DBusAudio *)hw->s->drv_opaque;
+    DBusVoiceIn *vo = container_of(hw, DBusVoiceIn, hw);
+    GHashTableIter iter;
+    QemuDBusDisplay1AudioInListener *listener = NULL;
+
+    vo->has_volume = true;
+    vo->volume = *vol;
+
+    g_hash_table_iter_init(&iter, da->in_listeners);
+    while (g_hash_table_iter_next(&iter, NULL, (void **)&listener)) {
+        dbus_volume_in_listener(hw, listener);
+    }
+}
+
+static size_t
+dbus_read(HWVoiceIn *hw, void *buf, size_t size)
+{
+    DBusAudio *da = (DBusAudio *)hw->s->drv_opaque;
+    /* DBusVoiceIn *vo = container_of(hw, DBusVoiceIn, hw); */
+    GHashTableIter iter;
+    QemuDBusDisplay1AudioInListener *listener = NULL;
+
+    trace_dbus_audio_read(size);
+
+    /* size = audio_rate_get_bytes(&hw->info, &vo->rate, size); */
+
+    g_hash_table_iter_init(&iter, da->in_listeners);
+    while (g_hash_table_iter_next(&iter, NULL, (void **)&listener)) {
+        g_autoptr(GVariant) v_data = NULL;
+        const char *data;
+        gsize n = 0;
+
+        if (qemu_dbus_display1_audio_in_listener_call_read_sync(
+                listener,
+                (uintptr_t)hw,
+                size,
+                G_DBUS_CALL_FLAGS_NONE, -1,
+                &v_data, NULL, NULL)) {
+            data = g_variant_get_fixed_array(v_data, &n, 1);
+            g_warn_if_fail(n <= size);
+            size = MIN(n, size);
+            memcpy(buf, data, size);
+            break;
+        }
+    }
+
+    return size;
+}
+
+static void
+dbus_enable_in(HWVoiceIn *hw, bool enable)
+{
+    DBusAudio *da = (DBusAudio *)hw->s->drv_opaque;
+    DBusVoiceIn *vo = container_of(hw, DBusVoiceIn, hw);
+    GHashTableIter iter;
+    QemuDBusDisplay1AudioInListener *listener = NULL;
+
+    vo->enabled = enable;
+    if (enable) {
+        audio_rate_start(&vo->rate);
+    }
+
+    g_hash_table_iter_init(&iter, da->in_listeners);
+    while (g_hash_table_iter_next(&iter, NULL, (void **)&listener)) {
+        qemu_dbus_display1_audio_in_listener_call_set_enabled(
+            listener, (uintptr_t)hw, enable,
+            G_DBUS_CALL_FLAGS_NONE, -1, NULL, NULL, NULL);
+    }
+}
+
+static void *
+dbus_audio_init(Audiodev *dev)
+{
+    DBusAudio *da = g_new0(DBusAudio, 1);
+
+    da->out_listeners = g_hash_table_new_full(g_str_hash, g_str_equal,
+                                                g_free, g_object_unref);
+    da->in_listeners = g_hash_table_new_full(g_str_hash, g_str_equal,
+                                               g_free, g_object_unref);
+    return da;
+}
+
+static void
+dbus_audio_fini(void *opaque)
+{
+    DBusAudio *da = opaque;
+
+    if (da->server) {
+        g_dbus_object_manager_server_unexport(da->server,
+                                              DBUS_DISPLAY1_AUDIO_PATH);
+    }
+    g_clear_object(&da->audio);
+    g_clear_object(&da->iface);
+    g_clear_pointer(&da->in_listeners, g_hash_table_unref);
+    g_clear_pointer(&da->out_listeners, g_hash_table_unref);
+    g_clear_object(&da->server);
+    g_free(da);
+}
+
+static void
+listener_out_vanished_cb(GDBusConnection *connection,
+                         gboolean remote_peer_vanished,
+                         GError *error,
+                         DBusAudio *da)
+{
+    char *name = g_object_get_data(G_OBJECT(connection), "name");
+
+    g_hash_table_remove(da->out_listeners, name);
+}
+
+static void
+listener_in_vanished_cb(GDBusConnection *connection,
+                        gboolean remote_peer_vanished,
+                        GError *error,
+                        DBusAudio *da)
+{
+    char *name = g_object_get_data(G_OBJECT(connection), "name");
+
+    g_hash_table_remove(da->in_listeners, name);
+}
+
+static gboolean
+dbus_audio_register_listener(AudioState *s,
+                             GDBusMethodInvocation *invocation,
+                             GUnixFDList *fd_list,
+                             GVariant *arg_listener,
+                             bool out)
+{
+    DBusAudio *da = s->drv_opaque;
+    const char *sender = g_dbus_method_invocation_get_sender(invocation);
+    g_autoptr(GDBusConnection) listener_conn = NULL;
+    g_autoptr(GError) err = NULL;
+    g_autoptr(GSocket) socket = NULL;
+    g_autoptr(GSocketConnection) socket_conn = NULL;
+    g_autofree char *guid = g_dbus_generate_guid();
+    GHashTable *listeners = out ? da->out_listeners : da->in_listeners;
+    GObject *listener;
+    int fd;
+
+    trace_dbus_audio_register(sender, out ? "out" : "in");
+
+    if (g_hash_table_contains(listeners, sender)) {
+        g_dbus_method_invocation_return_error(invocation,
+                                              DBUS_DISPLAY_ERROR,
+                                              DBUS_DISPLAY_ERROR_INVALID,
+                                              "`%s` is already registered!",
+                                              sender);
+        return DBUS_METHOD_INVOCATION_HANDLED;
+    }
+
+    fd = g_unix_fd_list_get(fd_list, g_variant_get_handle(arg_listener), &err);
+    if (err) {
+        g_dbus_method_invocation_return_error(invocation,
+                                              DBUS_DISPLAY_ERROR,
+                                              DBUS_DISPLAY_ERROR_FAILED,
+                                              "Couldn't get peer fd: %s",
+                                              err->message);
+        return DBUS_METHOD_INVOCATION_HANDLED;
+    }
+
+    socket = g_socket_new_from_fd(fd, &err);
+    if (err) {
+        g_dbus_method_invocation_return_error(invocation,
+                                              DBUS_DISPLAY_ERROR,
+                                              DBUS_DISPLAY_ERROR_FAILED,
+                                              "Couldn't make a socket: %s",
+                                              err->message);
+        return DBUS_METHOD_INVOCATION_HANDLED;
+    }
+    socket_conn = g_socket_connection_factory_create_connection(socket);
+    if (out) {
+        qemu_dbus_display1_audio_complete_register_out_listener(
+            da->iface, invocation, NULL);
+    } else {
+        qemu_dbus_display1_audio_complete_register_in_listener(
+            da->iface, invocation, NULL);
+    }
+
+    listener_conn =
+        g_dbus_connection_new_sync(
+            G_IO_STREAM(socket_conn),
+            guid,
+            G_DBUS_CONNECTION_FLAGS_AUTHENTICATION_SERVER,
+            NULL, NULL, &err);
+    if (err) {
+        error_report("Failed to setup peer connection: %s", err->message);
+        return DBUS_METHOD_INVOCATION_HANDLED;
+    }
+
+    listener = out ?
+        G_OBJECT(qemu_dbus_display1_audio_out_listener_proxy_new_sync(
+            listener_conn,
+            G_DBUS_PROXY_FLAGS_DO_NOT_AUTO_START,
+            NULL,
+            "/org/qemu/Display1/AudioOutListener",
+            NULL,
+            &err)) :
+        G_OBJECT(qemu_dbus_display1_audio_in_listener_proxy_new_sync(
+            listener_conn,
+            G_DBUS_PROXY_FLAGS_DO_NOT_AUTO_START,
+            NULL,
+            "/org/qemu/Display1/AudioInListener",
+            NULL,
+            &err));
+    if (!listener) {
+        error_report("Failed to setup proxy: %s", err->message);
+        return DBUS_METHOD_INVOCATION_HANDLED;
+    }
+
+    if (out) {
+        HWVoiceOut *hw;
+
+        QLIST_FOREACH(hw, &s->hw_head_out, entries) {
+            DBusVoiceOut *vo = container_of(hw, DBusVoiceOut, hw);
+            QemuDBusDisplay1AudioOutListener *l =
+                QEMU_DBUS_DISPLAY1_AUDIO_OUT_LISTENER(listener);
+
+            dbus_init_out_listener(l, hw);
+            qemu_dbus_display1_audio_out_listener_call_set_enabled(
+                l, (uintptr_t)hw, vo->enabled,
+                G_DBUS_CALL_FLAGS_NONE, -1, NULL, NULL, NULL);
+        }
+    } else {
+        HWVoiceIn *hw;
+
+        QLIST_FOREACH(hw, &s->hw_head_in, entries) {
+            DBusVoiceIn *vo = container_of(hw, DBusVoiceIn, hw);
+            QemuDBusDisplay1AudioInListener *l =
+                QEMU_DBUS_DISPLAY1_AUDIO_IN_LISTENER(listener);
+
+            dbus_init_in_listener(
+                QEMU_DBUS_DISPLAY1_AUDIO_IN_LISTENER(listener), hw);
+            qemu_dbus_display1_audio_in_listener_call_set_enabled(
+                l, (uintptr_t)hw, vo->enabled,
+                G_DBUS_CALL_FLAGS_NONE, -1, NULL, NULL, NULL);
+        }
+    }
+
+    g_object_set_data_full(G_OBJECT(listener_conn), "name",
+                           g_strdup(sender), g_free);
+    g_hash_table_insert(listeners, g_strdup(sender), listener);
+    g_object_connect(listener_conn,
+                     "signal::closed",
+                     out ? listener_out_vanished_cb : listener_in_vanished_cb,
+                     da,
+                     NULL);
+
+    return DBUS_METHOD_INVOCATION_HANDLED;
+}
+
+static gboolean
+dbus_audio_register_out_listener(AudioState *s,
+                                 GDBusMethodInvocation *invocation,
+                                 GUnixFDList *fd_list,
+                                 GVariant *arg_listener)
+{
+    return dbus_audio_register_listener(s, invocation,
+                                        fd_list, arg_listener, true);
+
+}
+
+static gboolean
+dbus_audio_register_in_listener(AudioState *s,
+                                GDBusMethodInvocation *invocation,
+                                GUnixFDList *fd_list,
+                                GVariant *arg_listener)
+{
+    return dbus_audio_register_listener(s, invocation,
+                                        fd_list, arg_listener, false);
+}
+
+static void
+dbus_audio_set_server(AudioState *s, GDBusObjectManagerServer *server)
+{
+    DBusAudio *da = s->drv_opaque;
+
+    g_assert(da);
+    g_assert(!da->server);
+
+    da->server = g_object_ref(server);
+
+    da->audio = g_dbus_object_skeleton_new(DBUS_DISPLAY1_AUDIO_PATH);
+    da->iface = qemu_dbus_display1_audio_skeleton_new();
+    g_object_connect(da->iface,
+                     "swapped-signal::handle-register-in-listener",
+                     dbus_audio_register_in_listener, s,
+                     "swapped-signal::handle-register-out-listener",
+                     dbus_audio_register_out_listener, s,
+                     NULL);
+
+    g_dbus_object_skeleton_add_interface(G_DBUS_OBJECT_SKELETON(da->audio),
+                                         G_DBUS_INTERFACE_SKELETON(da->iface));
+    g_dbus_object_manager_server_export(da->server, da->audio);
+}
+
+static struct audio_pcm_ops dbus_pcm_ops = {
+    .init_out = dbus_init_out,
+    .fini_out = dbus_fini_out,
+    .write    = audio_generic_write,
+    .get_buffer_out = dbus_get_buffer_out,
+    .put_buffer_out = dbus_put_buffer_out,
+    .enable_out = dbus_enable_out,
+    .volume_out = dbus_volume_out,
+
+    .init_in  = dbus_init_in,
+    .fini_in  = dbus_fini_in,
+    .read     = dbus_read,
+    .run_buffer_in = audio_generic_run_buffer_in,
+    .enable_in = dbus_enable_in,
+    .volume_in = dbus_volume_in,
+};
+
+static struct audio_driver dbus_audio_driver = {
+    .name            = "dbus",
+    .descr           = "Timer based audio exposed with DBus interface",
+    .init            = dbus_audio_init,
+    .fini            = dbus_audio_fini,
+    .set_dbus_server = dbus_audio_set_server,
+    .pcm_ops         = &dbus_pcm_ops,
+    .can_be_default  = 1,
+    .max_voices_out  = INT_MAX,
+    .max_voices_in   = INT_MAX,
+    .voice_size_out  = sizeof(DBusVoiceOut),
+    .voice_size_in   = sizeof(DBusVoiceIn)
+};
+
+static void register_audio_dbus(void)
+{
+    audio_driver_register(&dbus_audio_driver);
+}
+type_init(register_audio_dbus);
+
+module_dep("ui-dbus")