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, 235 insertions, 0 deletions

diff --git a/src/class/audio/audio_host.h b/src/class/audio/audio_host.h
new file mode 100644
index 000000000..6dd44f830
--- /dev/null
+++ b/src/class/audio/audio_host.h
@@ -0,0 +1,235 @@
+/*
+ * 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.
+ *
+ * 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.
+ *
+ * This file is part of the TinyUSB stack.
+ */
+
+#ifndef TUSB_AUDIO_HOST_H_
+#define TUSB_AUDIO_HOST_H_
+
+#include "audio.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+//--------------------------------------------------------------------+
+// Class Driver Configuration
+//--------------------------------------------------------------------+
+#ifndef CFG_TUH_AUDIO_MAX
+  #define CFG_TUH_AUDIO_MAX 1
+#endif
+
+#ifndef CFG_TUH_AUDIO_MAX_SAM_FREQ
+  #define CFG_TUH_AUDIO_MAX_SAM_FREQ 5
+#endif
+
+#ifndef CFG_TUH_AUDIO_MAX_AS
+  #define CFG_TUH_AUDIO_MAX_AS 4
+#endif
+
+//--------------------------------------------------------------------+
+// AS Interface Info (per-interface independent storage)
+//--------------------------------------------------------------------+
+typedef struct {
+  uint8_t interface_num;      // AS interface number
+  uint8_t alt_setting;        // Current alt setting
+  uint8_t ep_addr;            // Endpoint address
+  uint16_t ep_size;           // Max packet size
+  uint8_t ep_dir;             // TUSB_DIR_IN or TUSB_DIR_OUT
+
+  // Format info
+  uint8_t format_type;
+  uint8_t num_channels;
+  uint8_t sub_frame_size;
+  uint8_t bit_resolution;
+  uint8_t sam_freq_type;
+  uint32_t sam_freq[CFG_TUH_AUDIO_MAX_SAM_FREQ];
+  uint32_t sam_freq_lower;
+  uint32_t sam_freq_upper;
+} tuh_audio_as_info_t;
+
+#ifndef CFG_TUH_AUDIO_EPIN_BUFSIZE
+  #define CFG_TUH_AUDIO_EPIN_BUFSIZE 192
+#endif
+
+#ifndef CFG_TUH_AUDIO_EPOUT_BUFSIZE
+  #define CFG_TUH_AUDIO_EPOUT_BUFSIZE 192
+#endif
+
+//--------------------------------------------------------------------+
+// Descriptor Information
+//--------------------------------------------------------------------+
+// Information about parsed UAC 1.0 descriptors passed to the application
+// during enumeration (via tuh_audio_descriptor_cb)
+typedef struct {
+  // Audio Control Interface descriptor
+  const tusb_desc_interface_t *desc_ac_interface;
+
+  // Audio Streaming Interface descriptor (alt setting 0)
+  const tusb_desc_interface_t *desc_as_interface;
+
+  // Audio Streaming Interface alt setting (with endpoints)
+  const tusb_desc_interface_t *desc_as_interface_alt;
+
+  // Format Type descriptor
+  const uint8_t *desc_format_type;
+
+  // Class-Specific AS Interface (AS General) descriptor
+  const uint8_t *desc_cs_as_general;
+
+  // Standard Isochronous Endpoint descriptor (IN)
+  const tusb_desc_endpoint_t *desc_ep_in;
+
+  // Standard Isochronous Endpoint descriptor (OUT)
+  const tusb_desc_endpoint_t *desc_ep_out;
+
+  // Audio function information
+  uint8_t ac_interface_num;     // Audio Control interface number
+  uint8_t as_interface_num;       // Audio Streaming interface number
+  uint8_t alt_setting;          // Current alt setting with endpoints
+} tuh_audio_descriptor_cb_t;
+
+typedef struct {
+  uint8_t daddr;
+  uint8_t bInterfaceNumber;
+  uint8_t bAltSetting;
+
+  // Terminal info (from Audio Control Interface)
+  uint16_t input_terminal_type;         // wTerminalType of Input Terminal (0x0201 = Mic, etc.)
+  uint8_t input_terminal_id;            // bTerminalID of Input Terminal
+  uint8_t input_terminal_channels;      // bNrChannels of Input Terminal
+  uint16_t output_terminal_type;        // wTerminalType of Output Terminal (0x0301 = Speaker, etc.)
+  uint8_t output_terminal_id;           // bTerminalID of Output Terminal
+
+  // Feature Unit info
+  uint8_t feature_unit_id;              // bUnitID of Feature Unit (0 = none)
+  uint8_t feature_unit_source_id;       // bSourceID of Feature Unit
+
+  // Endpoint info
+  uint8_t ep_in;
+  uint8_t ep_out;
+  uint16_t ep_in_size;
+  uint16_t ep_out_size;
+
+  // Multi-AS support (per AS interface independent storage)
+  uint8_t as_count;
+  tuh_audio_as_info_t as_info[CFG_TUH_AUDIO_MAX_AS];
+} tuh_audio_mount_cb_t;
+
+//--------------------------------------------------------------------+
+// Application API
+//--------------------------------------------------------------------+
+
+// Check if Audio interface is mounted
+bool tuh_audio_mounted(uint8_t idx);
+
+// Get Interface index from device address + interface number
+// return TUSB_INDEX_INVALID_8 (0xFF) if not found
+uint8_t tuh_audio_itf_get_index(uint8_t daddr, uint8_t itf_num);
+
+// Get Interface information
+// return true if index is correct and interface is currently mounted
+bool tuh_audio_itf_get_info(uint8_t idx, tuh_itf_info_t *info);
+
+// Get number of AS interfaces for an audio device
+uint8_t tuh_audio_as_get_count(uint8_t idx);
+
+// Get AS interface info by index
+// as_idx: 0 to (as_count - 1)
+bool tuh_audio_as_get_info(uint8_t idx, uint8_t as_idx, tuh_audio_as_info_t *info);
+
+// Set Audio Streaming interface alternate setting (to enable/disable endpoints)
+bool tuh_audio_set_interface(uint8_t daddr, uint8_t itf_num, uint8_t alt_setting,
+                              tuh_xfer_cb_t complete_cb, uintptr_t user_data);
+
+//--------------------------------------------------------------------+
+// Control Endpoint API
+//--------------------------------------------------------------------+
+
+// Set current sampling frequency on an isochronous endpoint (UAC 1.0)
+// Sampling frequency is 3 bytes little-endian
+bool tuh_audio_set_sampling_freq(uint8_t daddr, uint8_t ep_addr, uint32_t sampling_freq,
+                                  tuh_xfer_cb_t complete_cb, uintptr_t user_data);
+
+// Get current sampling frequency from an isochronous endpoint (UAC 1.0)
+bool tuh_audio_get_sampling_freq(uint8_t daddr, uint8_t ep_addr, uint32_t *sampling_freq,
+                                  tuh_xfer_cb_t complete_cb, uintptr_t user_data);
+
+// Set current/mute/volume etc. for a feature unit (UAC 1.0)
+bool tuh_audio_feature_unit_set(uint8_t daddr, uint8_t itf_num, uint8_t unit_id,
+                                 uint8_t control_selector, uint8_t channel,
+                                 uint16_t value, tuh_xfer_cb_t complete_cb, uintptr_t user_data);
+
+// Get current/mute/volume etc. from a feature unit (UAC 1.0)
+bool tuh_audio_feature_unit_get(uint8_t daddr, uint8_t itf_num, uint8_t unit_id,
+                                 uint8_t control_selector, uint8_t channel,
+                                 void *buffer, uint8_t len,
+                                 tuh_xfer_cb_t complete_cb, uintptr_t user_data);
+
+//--------------------------------------------------------------------+
+// Interrupt/Isochronous Endpoint API
+//--------------------------------------------------------------------+
+
+// Submit an isochronous transfer to receive audio data from IN endpoint
+bool tuh_audio_receive(uint8_t daddr, uint8_t idx, uint8_t *buffer, uint16_t len);
+
+// Submit an isochronous transfer to send audio data to OUT endpoint
+bool tuh_audio_send(uint8_t daddr, uint8_t idx, uint8_t *buffer, uint16_t len);
+
+//--------------------------------------------------------------------+
+// Callbacks (Weak is optional)
+//--------------------------------------------------------------------+
+
+// Invoked when Audio interface descriptor is detected during enumeration.
+// Application can copy/parse descriptor if needed.
+// Note: may be fired before tuh_audio_mount_cb(), therefore audio interface is not mounted/ready.
+void tuh_audio_descriptor_cb(uint8_t idx, const tuh_audio_descriptor_cb_t *desc_cb_data);
+
+// Invoked when device with Audio interface is mounted
+void tuh_audio_mount_cb(uint8_t idx, const tuh_audio_mount_cb_t *mount_cb_data);
+
+// Invoked when device with Audio interface is un-mounted
+void tuh_audio_umount_cb(uint8_t idx);
+
+// Invoked when an isochronous IN transfer is complete
+void tuh_audio_rx_cb(uint8_t idx, uint8_t ep_addr, uint16_t xferred_bytes);
+
+// Invoked when an isochronous OUT transfer is complete
+void tuh_audio_tx_cb(uint8_t idx, uint8_t ep_addr, uint16_t xferred_bytes);
+
+//--------------------------------------------------------------------+
+// Internal Class Driver API
+//--------------------------------------------------------------------+
+bool     audioh_init(void);
+bool     audioh_deinit(void);
+uint16_t audioh_open(uint8_t rhport, uint8_t dev_addr, const tusb_desc_interface_t *desc_itf, uint16_t max_len);
+bool     audioh_set_config(uint8_t dev_addr, uint8_t itf_num);
+bool     audioh_xfer_cb(uint8_t dev_addr, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes);
+void     audioh_close(uint8_t daddr);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* TUSB_AUDIO_HOST_H_ */