feat: add MIDI 2.0 Device class driver (USB-MIDI 2.0)

Add native USB-MIDI 2.0 Device class driver to TinyUSB. Implements the
USB-MIDI 2.0 specification with both Alt Setting 0 (MIDI 1.0 fallback)
and Alt Setting 1 (UMP native) descriptor support.

Driver features:
- UMP (Universal MIDI Packet) read/write with atomic message framing
- Protocol negotiation: Endpoint Discovery, Config Request/Notify,
  Function Block Discovery (embedded in driver)
- Group Terminal Block descriptor via GET_DESCRIPTOR
- Alt Setting switch handler with endpoint re-arm
- Static allocation, no dynamic memory, ISR-safe

Build system:
- Register midi2d_* in usbd.c driver table
- Add TUD_MIDI2_DESCRIPTOR macros to usbd.h
- Add config defaults (CFG_TUD_MIDI2_*) to tusb_option.h
- Add midi2_ump_word_count() to midi.h (shared by Device and Host)
- Add midi2_device.c/h to family.cmake and CMakeLists.txt
- Add midi2_device.h include to tusb.h

All changes guarded by #if CFG_TUD_MIDI2 (default 0). Zero impact on
existing drivers and examples.

Tested: Raspberry Pi Pico (RP2040), Linux ALSA, Windows MIDI Services

1 files changed, 125 insertions, 0 deletions

diff --git a/src/class/midi/midi2_device.h b/src/class/midi/midi2_device.h
new file mode 100644
index 000000000..dac1f0124
--- /dev/null
+++ b/src/class/midi/midi2_device.h
@@ -0,0 +1,125 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2026 Saulo Verissimo
+ *
+ * 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_MIDI2_DEVICE_H_
+#define TUSB_MIDI2_DEVICE_H_
+
+#include "class/audio/audio.h"
+#include "midi.h"
+
+//--------------------------------------------------------------------+
+// Class Driver Configuration
+//--------------------------------------------------------------------+
+
+// Config defaults are in tusb_option.h:
+//   CFG_TUD_MIDI2_RX_EPSIZE, CFG_TUD_MIDI2_TX_EPSIZE,
+//   CFG_TUD_MIDI2_RX_BUFSIZE, CFG_TUD_MIDI2_TX_BUFSIZE,
+//   CFG_TUD_MIDI2_NUM_GROUPS, CFG_TUD_MIDI2_NUM_FUNCTION_BLOCKS,
+//   CFG_TUD_MIDI2_EP_NAME, CFG_TUD_MIDI2_PRODUCT_ID
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+//--------------------------------------------------------------------+
+// Application Callback API (weak, optional)
+//--------------------------------------------------------------------+
+void tud_midi2_rx_cb(uint8_t itf);
+void tud_midi2_set_itf_cb(uint8_t itf, uint8_t alt);
+bool tud_midi2_get_req_itf_cb(uint8_t rhport, const tusb_control_request_t* request);
+
+//--------------------------------------------------------------------+
+// Application API (Multiple Interfaces)
+//--------------------------------------------------------------------+
+
+bool     tud_midi2_n_mounted(uint8_t itf);
+uint32_t tud_midi2_n_available(uint8_t itf);
+uint8_t  tud_midi2_n_alt_setting(uint8_t itf);
+bool     tud_midi2_n_negotiated(uint8_t itf);
+uint8_t  tud_midi2_n_protocol(uint8_t itf);
+
+uint32_t tud_midi2_n_ump_read(uint8_t itf, uint32_t* words, uint32_t max_words);
+uint32_t tud_midi2_n_ump_write(uint8_t itf, const uint32_t* words, uint32_t count);
+
+bool     tud_midi2_n_packet_read(uint8_t itf, uint8_t packet[4]);
+bool     tud_midi2_n_packet_write(uint8_t itf, const uint8_t packet[4]);
+
+//--------------------------------------------------------------------+
+// Application API (Single Interface)
+//--------------------------------------------------------------------+
+TU_ATTR_ALWAYS_INLINE static inline bool tud_midi2_mounted(void) {
+  return tud_midi2_n_mounted(0);
+}
+
+TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_midi2_available(void) {
+  return tud_midi2_n_available(0);
+}
+
+TU_ATTR_ALWAYS_INLINE static inline uint8_t tud_midi2_alt_setting(void) {
+  return tud_midi2_n_alt_setting(0);
+}
+
+TU_ATTR_ALWAYS_INLINE static inline bool tud_midi2_negotiated(void) {
+  return tud_midi2_n_negotiated(0);
+}
+
+TU_ATTR_ALWAYS_INLINE static inline uint8_t tud_midi2_protocol(void) {
+  return tud_midi2_n_protocol(0);
+}
+
+TU_ATTR_ALWAYS_INLINE static inline uint32_t
+tud_midi2_ump_read(uint32_t* words, uint32_t max_words) {
+  return tud_midi2_n_ump_read(0, words, max_words);
+}
+
+TU_ATTR_ALWAYS_INLINE static inline uint32_t
+tud_midi2_ump_write(const uint32_t* words, uint32_t count) {
+  return tud_midi2_n_ump_write(0, words, count);
+}
+
+TU_ATTR_ALWAYS_INLINE static inline bool tud_midi2_packet_read(uint8_t packet[4]) {
+  return tud_midi2_n_packet_read(0, packet);
+}
+
+TU_ATTR_ALWAYS_INLINE static inline bool tud_midi2_packet_write(const uint8_t packet[4]) {
+  return tud_midi2_n_packet_write(0, packet);
+}
+
+//--------------------------------------------------------------------+
+// Internal Class Driver API
+//--------------------------------------------------------------------+
+void     midi2d_init(void);
+bool     midi2d_deinit(void);
+void     midi2d_reset(uint8_t rhport);
+uint16_t midi2d_open(uint8_t rhport, const tusb_desc_interface_t* itf_desc, uint16_t max_len);
+bool     midi2d_control_xfer_cb(uint8_t rhport, uint8_t stage, const tusb_control_request_t* request);
+bool     midi2d_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif