=====================
Audio drivers and HAL
=====================

The audio-fabric slice of the vendor driver/HAL layer — split out from the
general HAL catalogue (:doc:`/userspace/drivers-hals`) because it's by far
the largest single group (29 of the device's 37 loadable kernel modules) and
belongs next to the DSP firmware it drives (:doc:`dsp-firmware`).

Everything here is from ``vendor_a.img`` (``lib/modules/``, ``bin/hw/``,
``lib64/hw/``, ``etc/vintf/manifest.xml``) read with ``7z``, cross-checked
against ``kernel_config.txt``. No code was executed.

Loadable kernel modules
========================

``/vendor/lib/modules`` holds 37 ``.ko`` files total; **29 of them are the
audio fabric**, loading first (by ``modules.load`` order), in dependency
order, as the runtime drivers for the LPASS/Q6 DSP, the bolero on-die codec
macros, and the WCD/WSA codecs described in :doc:`dsp-firmware`:

.. list-table::
   :header-rows: 1
   :widths: 30 70

   * - Module group (load order)
     - Role / hardware
   * - ``audio_apr`` → ``audio_q6_pdr`` → ``audio_q6_notifier`` →
       ``audio_adsp_loader`` → ``audio_q6``
     - the Q6/ADSP transport: APR (Asynchronous Packet Router) messaging, PD
       restart, ADSP image load-notify, and the Q6 core — the userspace/kernel
       bridge to the audio DSP (:doc:`dsp-firmware`)
   * - ``audio_swr`` / ``audio_swr_ctrl`` / ``audio_pinctrl_lpi``
     - SoundWire master + LPI (low-power-island) pinctrl for the codec links
   * - ``audio_bolero_cdc`` + ``audio_{rx,tx,wsa,va}_macro``
     - the on-SoC **bolero** codec and its rx / tx / wsa / va macros (note the
       ``va`` macro module ships even though its DTB node is not wired —
       :doc:`dsp-firmware`)
   * - ``audio_wcd938x`` (+ ``_slave``), ``audio_wcd937x`` (+ ``_slave``),
       ``audio_wcd9xxx``, ``audio_wcd_core``, ``audio_mbhc``
     - the external WCD938x/937x codec(s) and the MBHC (headset button/jack)
       detection
   * - ``audio_wsa881x`` / ``audio_wsa883x``
     - the WSA smart-speaker-amp drivers (Class-D boosted speaker PAs)
   * - ``audio_platform`` / ``audio_native`` / ``audio_machine_lito`` /
       ``audio_snd_event`` / ``audio_hdmi`` / ``audio_stub`` / ``audio_usf``
     - the ASoC platform + machine driver (``lito``/lagoon sound card), the
       sound-event router, the (unused) HDMI DAI, a stub DAI, and USF
       (ultrasound framework)

The other 8 modules cover the rest of the peripheral fabric — not audio; see
:doc:`/userspace/drivers-hals`.

HAL service and implementation
================================

.. list-table::
   :header-rows: 1
   :widths: 26 40 34

   * - HAL
     - Implementation
     - Hardware / cross-ref
   * - ``audio.service`` + ``audio@6.0-impl``
     - ``audio.primary.lito.so`` (+ ``bluetooth``/``usb``/``r_submix``),
       ``soundtrigger``, ``audio.effect``
     - LPASS/Q6 + codecs (:doc:`dsp-firmware`)

The Bluetooth-audio HIDL client (``bluetooth_audio``, part of the
``bluetooth@1.0-service-qti`` HAL) lives in :doc:`/wireless/hal` — it's a
Bluetooth HAL entry, not part of the primary audio HAL, even though it
carries audio data.

Provenance
==========

:Source: ``artifacts/super/vendor_a.img`` — ``lib/modules/{*.ko,modules.load}``
   (module set + boot load order), ``bin/hw/*`` and ``lib64/hw/*`` (HAL
   service and implementation libraries), ``etc/vintf/manifest.xml`` (HAL
   declaration); ``artifacts/boot_a/kernel_config.txt``.
:Method: ext4 image listed/extracted read-only with ``7z``; modules counted
   from ``modules.load``; HAL from ``bin/hw`` / ``lib64/hw`` names and the
   VINTF manifest. No code executed.
:Cross-refs: :doc:`dsp-firmware` (the DSP firmware these modules load and
   drive), :doc:`/userspace/drivers-hals` (the rest of the HAL/module
   catalogue, including generic platform HALs), :doc:`/wireless/hal`
   (Bluetooth audio HIDL client).