[PATCH v11 11/11] docs/system: add basic virtio-snd documentation

[Manos Pitsidianakis <manos.pitsidianakis@linaro.org>]

From: Emmanouil Pitsidianakis <manos.pitsidianakis@linaro.org>

This commit adds basic documentation for using virtio-snd.

Signed-off-by: Emmanouil Pitsidianakis <manos.pitsidianakis@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
---
 MAINTAINERS                              |  1 +
 docs/system/device-emulation.rst         |  1 +
 docs/system/devices/virtio-snd.rst (new) | 49 ++++++++++++++++++++++++
 3 files changed, 51 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 701f12026a..a32e512a61 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2259,6 +2259,7 @@ M: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
 S: Supported
 F: hw/virtio/virtio-snd*.c
 F: include/hw/virtio/virtio-snd.h
+F: docs/system/devices/virtio-snd.rst
 
 nvme
 M: Keith Busch <kbusch@kernel.org>
diff --git a/docs/system/device-emulation.rst b/docs/system/device-emulation.rst
index 4491c4cbf7..dae19446e5 100644
--- a/docs/system/device-emulation.rst
+++ b/docs/system/device-emulation.rst
@@ -79,20 +79,21 @@ in a PCI slot to the exclusive use of the guest.
 Emulated Devices
 ~~~~~~~~~~~~~~~~
 
 .. toctree::
    :maxdepth: 1
 
    devices/can.rst
    devices/ccid.rst
    devices/cxl.rst
    devices/ivshmem.rst
    devices/keyboard.rst
    devices/net.rst
    devices/nvme.rst
    devices/usb.rst
    devices/vhost-user.rst
    devices/virtio-pmem.rst
+   devices/virtio-snd.rst
    devices/vhost-user-rng.rst
    devices/canokey.rst
    devices/usb-u2f.rst
    devices/igb.rst
diff --git a/docs/system/devices/virtio-snd.rst b/docs/system/devices/virtio-snd.rst
new file mode 100644
index 0000000000..2a9187fd70
--- /dev/null
+++ b/docs/system/devices/virtio-snd.rst
@@ -0,0 +1,49 @@
+virtio sound
+============
+
+This document explains the setup and usage of the Virtio sound device.
+The Virtio sound device is a paravirtualized sound card device.
+
+Linux kernel support
+--------------------
+
+Virtio sound requires a guest Linux kernel built with the
+``CONFIG_SND_VIRTIO`` option.
+
+Description
+-----------
+
+Virtio sound implements capture and playback from inside a guest using the
+configured audio backend of the host machine.
+
+Device properties
+-----------------
+
+The Virtio sound device can be configured with the following properties:
+
+ * ``jacks`` number of physical jacks (Unimplemented).
+ * ``streams`` number of PCM streams. At the moment, no stream configuration is supported: the first one will always be a playback stream, an optional second will always be a capture stream. Adding more will cycle stream directions from playback to capture.
+ * ``chmaps`` number of channel maps (Unimplemented).
+
+All streams are stereo and have the default channel positions ``Front left, right``.
+
+Examples
+--------
+
+Add an audio device and an audio backend at once with ``-audio`` and ``model=virtio``:
+
+ * pulseaudio: ``-audio driver=pa,model=virtio``
+   or ``-audio driver=pa,model=virtio,server=/run/user/1000/pulse/native``
+ * sdl: ``-audio driver=sdl,model=virtio``
+ * coreaudio: ``-audio driver=coreaudio,model=virtio``
+
+etc.
+
+To specifically add virtualized sound devices, you have to specify a PCI device
+and an audio backend listed with ``-audio driver=help`` that works on your host
+machine, e.g.:
+
+::
+
+  -device virtio-sound-pci,audiodev=my_audiodev \
+  -audiodev alsa,id=my_audiodev
-- 
2.39.2