docs: platforms: add ESP32-C6 platform support and loopback bridge

Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>

Author: lrgirdwo

architectures/index.rst

@@ -11,7 +11,7 @@ System & Software Architecture
 The SOF software ecosystem supports two foundational deployment models tailored for different device form-factors:
 
 1. **Host-Based Architecture**: Where the audio DSP is coupled to an application processor running a general-purpose operating system (**Linux**, **Android**, or **ChromeOS**). The host manages firmware lifecycle, parses topologies, and streams audio over DMA memory windows via inter-processor communication (IPC).
-2. **Hostless (Standalone / Embedded) Architecture**: Where SOF firmware runs autonomously directly on a microcontroller or standalone DSP (such as the **ESP32-P4** or **Teensy 4.1 / i.MX RT1062**) atop Zephyr RTOS without requiring a host CPU or external operating system.
+2. **Hostless (Standalone / Embedded) Architecture**: Where SOF firmware runs autonomously directly on a microcontroller or standalone DSP (such as the **ESP32-P4 / ESP32-C6** or **Teensy 4.1 / i.MX RT1062**) atop Zephyr RTOS without requiring a host CPU or external operating system.
 
 Host-Based System & Software Architecture
 =========================================
@@ -194,7 +194,7 @@ The host-side driver is integrated directly upstream in the mainline Linux kerne
 Hostless (Standalone) Embedded Architecture
 ===========================================
 
-In hostless deployments (such as smart speakers, conference microphones, standalone audio bridges, hearing aids, IoT voice endpoints, and embedded test cards like the **ESP32-P4** and **Teensy 4.1 / i.MX RT1062**), SOF executes completely autonomously without requiring a host processor or general-purpose operating system:
+In hostless deployments (such as smart speakers, conference microphones, standalone audio bridges, hearing aids, IoT voice endpoints, and embedded test cards like the **ESP32-P4**, **ESP32-C6**, and **Teensy 4.1 / i.MX RT1062**), SOF executes completely autonomously without requiring a host processor or general-purpose operating system:
 
 * **Autonomous Zephyr Application**: SOF operates as a self-contained Zephyr RTOS native application. It initializes on-chip peripherals, configures audio clocks, and begins pipeline processing immediately upon boot without waiting for host firmware downloads or handshakes.
 * **Static Pre-Compiled Topologies**: Instead of relying on a host kernel driver to dynamically parse binary ``.tplg`` files at runtime, hostless systems utilize pre-compiled static topology graphs embedded directly in firmware flash ROM or compiled into static C data structures.
@@ -203,7 +203,7 @@ In hostless deployments (such as smart speakers, conference microphones, standal
 * **Local Controls & Embedded Telemetry**: Volume, mute, EQ profiles, and audio routing are controlled locally via GPIO buttons, rotary encoders, or local Zephyr application threads, with real-time diagnostic trace logging streamed over UART or USB CDC.
 
 .. graphviz::
-   :caption: SOF Hostless Embedded System Architecture (ESP32-P4 / Teensy 4.1)
+   :caption: SOF Hostless Embedded System Architecture (ESP32-P4 / ESP32-C6 / Teensy 4.1)
    :align: center
 
    digraph hostless_stack {
@@ -241,7 +241,7 @@ In hostless deployments (such as smart speakers, conference microphones, standal
 
        // 2. HOSTLESS AUDIO DSP FIRMWARE (MIDDLE)
        subgraph cluster_firmware {
-           label = "Hostless SOF Firmware (ESP32-P4 / Teensy 4.1 / Embedded MCU)";
+           label = "Hostless SOF Firmware (ESP32-P4 / ESP32-C6 / Teensy 4.1 / Embedded MCU)";
            style = "filled,rounded";
            color = "#27ae60";
            fillcolor = "#eafaf1";

data/platforms.yaml

@@ -622,6 +622,27 @@ platforms:
     status: Active Integration
     notes: "Essential test card for automated I2S/PDM loopback verification across Spider and Aphid"
 
+  - id: esp32_c6
+    vendor: Espressif
+    family: ESP32-C6
+    name: ESP32-C6 Audio Node & Loopback Bridge
+    dsp_arch: RISC-V Single-Core HP (RV32IMAC)
+    cores: 1
+    clock_range: "160 MHz"
+    platform_clock: "40 MHz XTAL"
+    memory: "512 KB HP SRAM / 320 KB ROM"
+    audio_interfaces:
+      - "I2S (Controller & Target mode, S16_LE stereo playback/capture)"
+      - "Dynamic DAI Discovery & Static Volume Controls"
+      - "Hardware Loopback Bridge (XIAO / Waveshare C6-Zero)"
+    ipc_versions:
+      - N/A
+    zephyr_target: "xiao_esp32c6/esp32c6/hpcore, esp32c6_devkitc"
+    target_alias: esp32-c6
+    test_dut: "Seeed XIAO (Tx) / Waveshare C6-Zero (Rx) Pair"
+    status: Active Integration
+    notes: "Ultra-low-power RISC-V audio node with automated hardware loopback verification (PR #11200)"
+
   - id: qemu_sim
     vendor: Emulation
     family: Simulation

faq/index.rst

@@ -270,7 +270,7 @@ and implement software quirks:
 
 Can SOF run without a host computer?
 ====================================
-Yes. The **Hostless (Standalone) Architecture** allows SOF to run independently on microcontrollers and embedded processors such as the **Teensy 4.1 (ARM Cortex-M7)** and **ESP32-P4 (dual-core RISC-V)**. In hostless mode, pipelines are instantiated at boot from static ROM configurations, processing audio directly between local microphones, line-ins, codecs, and Bluetooth transceivers.
+Yes. The **Hostless (Standalone) Architecture** allows SOF to run independently on microcontrollers and embedded processors such as the **Teensy 4.1 (ARM Cortex-M7)**, **ESP32-P4 (dual-core RISC-V)**, and **ESP32-C6 (single-core RISC-V)**. In hostless mode, pipelines are instantiated at boot from static ROM configurations, processing audio directly between local microphones, line-ins, codecs, and Bluetooth transceivers.
 
 What physical audio buses and peripherals are supported?
 ========================================================

introduction/index.rst

@@ -37,7 +37,7 @@ Architecture Overview
 Sound Open Firmware supports two foundational deployment models tailored for diverse device form-factors:
 
 * **Host-Based Architecture**: Where the audio DSP is coupled to a host application processor running **Linux**, **Android**, or **ChromeOS**. The host OS driver stack (mainline Linux ``sound/soc/sof/``) manages firmware lifecycle, dynamic topology loading, and power management (D0ix/D3), while audio data streams through host DMA memory windows via IPC (IPC3/IPC4).
-* **Hostless (Standalone / Embedded) Architecture**: Where SOF runs autonomously on microcontrollers and standalone DSPs (such as the **ESP32-P4** or **Teensy 4.1 / i.MX RT1062**) atop the Zephyr RTOS. These systems process audio directly between physical hardware peripherals (I2S, SoundWire, PDM microphones, and Bluetooth transceivers) using ROM-embedded static topologies.
+* **Hostless (Standalone / Embedded) Architecture**: Where SOF runs autonomously on microcontrollers and standalone DSPs (such as the **ESP32-P4 / ESP32-C6** or **Teensy 4.1 / i.MX RT1062**) atop the Zephyr RTOS. These systems process audio directly between physical hardware peripherals (I2S, SoundWire, PDM microphones, and Bluetooth transceivers) using ROM-embedded static topologies.
 
 .. seealso::
    For complete system stack diagrams, hostless designs, real-time pipeline DAGs, and memory hierarchy details, refer to the comprehensive :ref:`Architecture & System Design <architectures>` documentation.