USB: Device_next: Add USB MTP class support

Implement a basic version of USB MTP (Media transfer protocol) class
which support the necessary MTP commands to handle Dir/file
transfer between a device and host.

Signed-off-by: Mohamed ElShahawi <ExtremeGTX@hotmail.com>

Author: ExtremeGTX

dts/bindings/fs/zephyr,fstab-common.yaml

@@ -43,3 +43,8 @@ properties:
 
       This causes the FS_MOUNT_FLAG_USE_DISK_ACCESS option to be set in
       the mount descriptor generated for the file system.
+
+  mtp-enabled:
+    type: boolean
+    description: |
+      Provide File system access over USB MTP Protocol

include/zephyr/usb/usb_ch9.h

@@ -264,6 +264,7 @@ struct usb_association_descriptor {
 #define USB_BCC_AUDIO			0x01
 #define USB_BCC_CDC_CONTROL		0x02
 #define USB_BCC_HID			0x03
+#define USB_BCC_IMAGE                   0x06
 #define USB_BCC_MASS_STORAGE		0x08
 #define USB_BCC_CDC_DATA		0x0A
 #define USB_BCC_VIDEO			0x0E

subsys/usb/device_next/CMakeLists.txt

@@ -104,4 +104,10 @@ zephyr_linker_sources_ifdef(
   SECTIONS class/usbd_dfu.ld
 )
 
+zephyr_library_sources_ifdef(
+	CONFIG_USBD_MTP_CLASS
+	class/usbd_mtp.c
+	class/usbd_mtp_class.c
+)
+
 zephyr_linker_sources(DATA_SECTIONS usbd_data.ld)

subsys/usb/device_next/class/Kconfig

@@ -13,3 +13,4 @@ rsource "Kconfig.hid"
 rsource "Kconfig.midi2"
 rsource "Kconfig.dfu"
 rsource "Kconfig.uvc"
+rsource "Kconfig.mtp"

subsys/usb/device_next/class/Kconfig.mtp

@@ -0,0 +1,35 @@
+# Copyright (c) 2025 Mohamed ElShahawi (extremegtx@hotmail.com)
+#
+# SPDX-License-Identifier: Apache-2.0
+
+config USBD_MTP_CLASS
+	bool "USB MTP Class"
+	help
+	  USB Media Transfer Protocol Device Class support.
+	  Allow file transfer independent of storage file system.
+
+if USBD_MTP_CLASS
+
+config USBD_MTP_MAX_HANDLES
+	int "Max number of Object handles per Storage"
+	default 10
+	help
+	  Maximum number of objects to be handled by MTP, including
+	  stored, removed and added objects.
+
+config RECYCLE_OBJECT_HANDLES
+	bool "Recycle Object Handles"
+	default n
+	help
+	  Recycle object handles when the maximum number of objects is reached.
+	  If disabled, new objects will not be added when the maximum number of
+	  objects is reached. Although this option provide better usability,
+	  it is against the MTP specification.
+
+module = USBD_MTP
+module-str = usbd mtp
+default-count = 1
+source "subsys/logging/Kconfig.template.log_config"
+
+rsource "Kconfig.template.instances_count"
+endif