feat(audio): add USB Audio Host (UAC 1.0) support

Add TinyUSB Host Audio class driver supporting UAC 1.0 devices.

Features:
- Support multiple Audio Streaming (AS) interfaces with independent format storage
- Support both IN (Microphone) and OUT (Speaker) endpoints
- Per-AS interface format info: channels, sample rate, bit resolution
- Support Feature Unit volume control
- Support sampling frequency get/set
- Add host/audio_host example for STM32F407 discovery board
- Support mono-to-stereo conversion for loopback

Changes:
- Add src/class/audio/audio_host.c and audio_host.h
- Register AUDIO driver in usbh.c
- Add CFG_TUH_AUDIO macro in tusb_option.h
- Add host/audio_host example with CMake and Makefile build support

Tested with Jabra USB headset (stereo speaker + mono microphone) on STM32F407 disco.

1 files changed, 73 insertions, 0 deletions

diff --git a/examples/host/audio_host/src/main.c b/examples/host/audio_host/src/main.c
new file mode 100644
index 000000000..b80cd2938
--- /dev/null
+++ b/examples/host/audio_host/src/main.c
@@ -0,0 +1,73 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2025 TinyUSB contributors
+ *
+ * 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.
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "bsp/board_api.h"
+#include "tusb.h"
+#include "app.h"
+
+//--------------------------------------------------------------------+
+// MACRO CONSTANT TYPEDEF PROTYPES
+//--------------------------------------------------------------------+
+void led_blinking_task(void);
+
+/*------------- MAIN -------------*/
+int main(void) {
+  board_init();
+
+  printf("TinyUSB Host USB Audio Example\r\n");
+  printf("Connect a USB Audio Device (UAC 1.0) to test\r\n");
+
+  // init host stack on configured roothub port
+  tusb_rhport_init_t host_init = {
+    .role = TUSB_ROLE_HOST,
+    .speed = TUSB_SPEED_AUTO
+  };
+  tusb_init(BOARD_TUH_RHPORT, &host_init);
+
+  board_init_after_tusb();
+
+  while (1) {
+    // tinyusb host task
+    tuh_task();
+    led_blinking_task();
+    audio_app_task();
+  }
+}
+
+//--------------------------------------------------------------------+
+// TinyUSB Callbacks
+//--------------------------------------------------------------------+
+
+//--------------------------------------------------------------------+
+// Blinking Task
+//--------------------------------------------------------------------+
+void led_blinking_task(void) {
+  const uint32_t interval_ms = 1000;
+  static uint32_t start_ms = 0;
+
+  static bool led_state = false;
+
+  // Blink every interval ms
+  if ( tusb_time_millis_api() - start_ms < interval_ms) return; // not enough time
+  start_ms += interval_ms;
+
+  board_led_write(led_state);
+  led_state = 1 - led_state; // toggle
+}