Refactor TUH_AUDIO API and simplify multi-AS interface support

This commit refactors the TUH_AUDIO (USB Audio Host) class driver to
simplify its public API and improve multi-AS (Audio Streaming) interface
support. The changes are focused on three files: the core driver
(audio_host.c/h) and the example application (audio_app.c).

Key changes in src/class/audio/audio_host.h:
- Remove tuh_audio_descriptor_cb_t and tuh_audio_mount_cb_t structures.
  The mount callback no longer passes a large descriptor-info struct;
  applications query per-AS info via tuh_audio_as_get_info().
- Add tuh_audio_get_dev_addr() and tuh_audio_get_feature_unit_id()
  accessors to retrieve device address and feature-unit ID from an
  interface index.
- Simplify control-transfer APIs by replacing (daddr, itf_num, unit_id)
  parameters with a single idx parameter:
    tuh_audio_set_sampling_freq(idx, as_idx, ...)
    tuh_audio_get_sampling_freq(idx, as_idx, ...)
    tuh_audio_feature_unit_set(idx, control_selector, channel, ...)
    tuh_audio_feature_unit_get(idx, control_selector, channel, ...)
- Add synchronous wrapper APIs using TU_API_SYNC macro:
    tuh_audio_get_sampling_freq_sync()
    tuh_audio_set_sampling_freq_sync()
    tuh_audio_feature_unit_set_sync()
    tuh_audio_feature_unit_get_sync()
- Update isochronous endpoint APIs to use (idx, as_idx) instead of
  (daddr, idx):
    tuh_audio_receive(idx, as_idx, buffer, len)
    tuh_audio_send(idx, as_idx, buffer, len)
- Remove tuh_audio_descriptor_cb() weak callback.
- Update tuh_audio_mount_cb() signature from mount_cb(param) to no param.
- Update tuh_audio_rx_cb()/tuh_audio_tx_cb() first parameter from idx to
  dev_addr for consistency with other class drivers.

Key changes in src/class/audio/audio_host.c:
- Delete tuh_audio_descriptor_cb weak stub.
- Refactor get_idx_by_ep_addr() to iterate all AS interfaces per device
  instead of relying on single ep_in/ep_out fields.
- Add audioh_get_ep_addr_by_dir() helper to find an endpoint address by
  direction across multiple AS interfaces.
- Simplify audioh_close() cleanup: remove now-removed single-endpoint
  fields (ep_in, ep_out) and rely on tu_memclr(p_audio->as, ...).
- Update audioh_xfer_cb() to pass dev_addr (not idx) to rx/tx callbacks,
  matching the new callback signature.
- Simplify audioh_open(): remove descriptor-callback emission and the
  temporary desc_cb structure; store only ac_itf_num instead of
  bInterfaceNumber + iInterface + as_interface_num.
- Rename local descriptor pointers for clarity:
    desc_input_terminal (was desc_it)
    desc_output_terminal (was desc_ot)

Key changes in examples/host/audio_host/src/audio_app.c:
- Remove now-unnecessary globals: audio_ep_in, audio_ep_out, audio_ac_itf,
  audio_feature_unit_id.
- Initialize audio_dev_addr, audio_idx, audiostream_in_idx,
  audiostream_out_idx to 0xFF (TUSB_INDEX_INVALID_8) instead of 0.
- Update print_as_interfaces() to use tuh_audio_as_get_count() and
  tuh_audio_as_get_info() instead of accessing mount_cb_data.
- Update all callback signatures and API calls to match the new driver API.

1 files changed, 65 insertions, 98 deletions

diff --git a/src/class/audio/audio_host.h b/src/class/audio/audio_host.h
index 5c5a8b3df..aafd58f43 100644
--- a/src/class/audio/audio_host.h
+++ b/src/class/audio/audio_host.h
@@ -17,14 +17,15 @@ extern "C" {
 //--------------------------------------------------------------------+
 // Class Driver Configuration
 //--------------------------------------------------------------------+
+// Maximum number of Audio interfaces per Audio device
 #ifndef CFG_TUH_AUDIO_MAX
   #define CFG_TUH_AUDIO_MAX 1
 #endif
-
+// Maximum number of Audio Streaming interfaces per Audio device
 #ifndef CFG_TUH_AUDIO_MAX_SAM_FREQ
   #define CFG_TUH_AUDIO_MAX_SAM_FREQ 5
 #endif
-
+// Maximum number of Audio Streaming interfaces per Audio device
 #ifndef CFG_TUH_AUDIO_MAX_AS
   #define CFG_TUH_AUDIO_MAX_AS 4
 #endif
@@ -33,18 +34,18 @@ extern "C" {
 // 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
+  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;
+  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;
@@ -59,72 +60,15 @@ typedef struct {
 #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 device address of Audio interface
+uint8_t tuh_audio_get_dev_addr(uint8_t idx);
+// Get Feature Unit ID
+uint8_t tuh_audio_get_feature_unit_id(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);
@@ -141,8 +85,8 @@ uint8_t tuh_audio_as_get_count(uint8_t idx);
 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);
+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
@@ -150,54 +94,77 @@ bool tuh_audio_set_interface(uint8_t daddr, uint8_t itf_num, uint8_t alt_setting
 
 // 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);
+// In multi-AS scenarios, pass the endpoint address from tuh_audio_as_get_info().
+bool tuh_audio_set_sampling_freq(uint8_t idx, uint8_t as_idx, 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);
+// In multi-AS scenarios, pass the endpoint address from tuh_audio_as_get_info().
+bool tuh_audio_get_sampling_freq(uint8_t idx, uint8_t as_idx, 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);
+bool tuh_audio_feature_unit_set(uint8_t idx, 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);
+bool tuh_audio_feature_unit_get(uint8_t idx, uint8_t control_selector, uint8_t channel, uint16_t *value,
+                                tuh_xfer_cb_t complete_cb, uintptr_t user_data);
+
+//--------------------------------------------------------------------+
+// Control Request Sync API
+// Each Function will make a USB control transfer request to/from device the function will block until request is
+// complete. The function will return the transfer request result
+//--------------------------------------------------------------------+
+TU_ATTR_ALWAYS_INLINE static inline tusb_xfer_result_t tuh_audio_get_sampling_freq_sync(uint8_t idx, uint8_t as_idx,
+                                                                                        uint32_t *sampling_freq) {
+  TU_API_SYNC(tuh_audio_get_sampling_freq, idx, as_idx, sampling_freq);
+}
+
+TU_ATTR_ALWAYS_INLINE static inline tusb_xfer_result_t tuh_audio_set_sampling_freq_sync(uint8_t idx, uint8_t as_idx,
+                                                                                        uint32_t sampling_freq) {
+  TU_API_SYNC(tuh_audio_set_sampling_freq, idx, as_idx, sampling_freq);
+}
+
+TU_ATTR_ALWAYS_INLINE static inline tusb_xfer_result_t
+tuh_audio_feature_unit_set_sync(uint8_t idx, uint8_t control_selector, uint8_t channel, uint16_t value) {
+  TU_API_SYNC(tuh_audio_feature_unit_set, idx, control_selector, channel, value);
+}
+
+TU_ATTR_ALWAYS_INLINE static inline tusb_xfer_result_t
+tuh_audio_feature_unit_get_sync(uint8_t idx, uint8_t control_selector, uint8_t channel, uint16_t *value) {
+  TU_API_SYNC(tuh_audio_feature_unit_get, idx, control_selector, channel, value);
+}
 
 //--------------------------------------------------------------------+
 // 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 receive audio data from a default IN endpoint.
+// In multi-AS scenarios, endpoint selection is implementation-defined default behavior.
+// Use tuh_audio_as_get_info() when application needs explicit per-AS endpoint control.
+bool tuh_audio_receive(uint8_t idx, uint8_t as_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);
+// Submit an isochronous transfer to send audio data to a default OUT endpoint.
+// In multi-AS scenarios, endpoint selection is implementation-defined default behavior.
+// Use tuh_audio_as_get_info() when application needs explicit per-AS endpoint control.
+bool tuh_audio_send(uint8_t idx, uint8_t as_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);
+void tuh_audio_mount_cb(uint8_t idx);
 
 // 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);
+void tuh_audio_rx_cb(uint8_t dev_addr, 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);
+void tuh_audio_tx_cb(uint8_t dev_addr, uint8_t ep_addr, uint16_t xferred_bytes);
 
 //--------------------------------------------------------------------+
 // Internal Class Driver API