boot: zephyr: migrate CDC ACM serial recovery to USB_DEVICE_STACK_NEXT

boot/zephyr/CMakeLists.txt

@@ -312,6 +312,10 @@ if(CONFIG_MCUBOOT_SERIAL)
       zephyr_sources(boot_serial_extension_zephyr_basic.c)
     endif()
   endif()
+
+  if(CONFIG_BOOT_SERIAL_CDC_ACM)
+    zephyr_sources(usbd_cdc_serial.c)
+  endif()
 endif()
 
 if(NOT CONFIG_BOOT_SIGNATURE_TYPE_NONE AND NOT CONFIG_BOOT_BUILTIN_KEY AND NOT

boot/zephyr/Kconfig.serial_recovery

@@ -37,7 +37,8 @@ config BOOT_SERIAL_UART
 
 config BOOT_SERIAL_CDC_ACM
 	bool "CDC ACM"
-	select USB_DEVICE_STACK
+	select USB_DEVICE_STACK_NEXT
+	select USBD_CDC_ACM_CLASS
 	help
 	  This setting will choose CDC ACM for serial recovery unless chosen
 	  "zephyr,uart-mcumgr" is present, in which case the chosen takes
@@ -46,6 +47,51 @@ config BOOT_SERIAL_CDC_ACM
 
 endchoice
 
+if BOOT_SERIAL_CDC_ACM
+
+config BOOT_SERIAL_CDC_ACM_VID
+	hex "USB Vendor ID for CDC ACM serial recovery"
+	default 0x2fe3
+	help
+	  USB Vendor ID presented during serial recovery mode.
+		You must use your own VID for samples and applications outside of Zephyr Project.
+
+config BOOT_SERIAL_CDC_ACM_PID
+	hex "USB Product ID for CDC ACM serial recovery"
+	default 0x0004
+	help
+	  USB Product ID presented during serial recovery mode.
+		You must use your own PID for samples and applications outside of Zephyr Project.
+
+config BOOT_SERIAL_CDC_ACM_MANUFACTURER_STRING
+	string "USB manufacturer string for CDC ACM serial recovery"
+	default "MCUBoot"
+	help
+	  USB manufacturer string descriptor for serial recovery mode.
+
+config BOOT_SERIAL_CDC_ACM_PRODUCT_STRING
+	string "USB product string for CDC ACM serial recovery"
+	default "CDC ACM serial recovery"
+	help
+	  USB product string descriptor for serial recovery mode.
+
+config BOOT_SERIAL_CDC_ACM_SELF_POWERED
+	bool "USB self-powered attribute for CDC ACM serial recovery"
+	help
+	  Set the Self-powered attribute in the USB configuration descriptor.
+	  When enabled, the device reports that it does not draw power from
+	  the USB bus. Only enable this if the device is powered by an
+	  independent supply during serial recovery mode.
+
+config BOOT_SERIAL_CDC_ACM_MAX_POWER
+	int "USB bMaxPower value for CDC ACM serial recovery"
+	default 125
+	range 0 250
+	help
+	  bMaxPower value in the configuration in 2 mA units.
+
+endif # BOOT_SERIAL_CDC_ACM
+
 config MCUBOOT_SERIAL_DIRECT_IMAGE_UPLOAD
 	bool "Allow to select image number for DFU"
 	depends on !SINGLE_APPLICATION_SLOT

boot/zephyr/boards/nrf52840_big.overlay

@@ -17,17 +17,17 @@
 
 		boot_partition: partition@0 {
 			label = "mcuboot";
-			reg = <0x000000000 0x00010000>;
+			reg = <0x000000000 0x00012000>;
 		};
 
-		slot0_partition: partition@10000 {
+		slot0_partition: partition@12000 {
 			label = "image-0";
-			reg = <0x000010000 0x000074000>;
+			reg = <0x000012000 0x000073000>;
 		};
 
-		slot1_partition: partition@75000 {
+		slot1_partition: partition@85000 {
 			label = "image-1";
-			reg = <0x00084000 0x000074000>;
+			reg = <0x00085000 0x000073000>;
 		};
 	};
 };

boot/zephyr/boards/nrf52840dongle_nrf52840.conf

@@ -18,9 +18,4 @@ CONFIG_BOOT_SERIAL_CDC_ACM=y
 # Required by USB
 CONFIG_MULTITHREADING=y
 
-# USB
-CONFIG_USB_DEVICE_STACK=y
-CONFIG_USB_DEVICE_REMOTE_WAKEUP=n
-CONFIG_USB_DEVICE_PRODUCT="MCUBOOT"
-
 CONFIG_NORDIC_QSPI_NOR=n

boot/zephyr/boards/nrf52840dongle_nrf52840_big.overlay

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2026 Tolt Technologies
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/delete-node/ &boot_partition;
+/delete-node/ &slot0_partition;
+/delete-node/ &slot1_partition;
+
+&flash0 {
+	partitions {
+		compatible = "fixed-partitions";
+		#address-cells = <1>;
+		#size-cells = <1>;
+
+		boot_partition: partition@1000 {
+			label = "mcuboot";
+			reg = <0x00001000 0x00010000>;
+		};
+
+		slot0_partition: partition@11000 {
+			label = "image-0";
+			reg = <0x00011000 0x00065000>;
+		};
+
+		slot1_partition: partition@76000 {
+			label = "image-1";
+			reg = <0x00076000 0x00065000>;
+		};
+	};
+};

boot/zephyr/main.c

@@ -90,6 +90,18 @@ const struct boot_uart_funcs boot_funcs = {
 #include <zephyr/usb/class/usb_dfu.h>
 #endif
 
+#ifdef CONFIG_USB_DEVICE_STACK_NEXT
+#include <zephyr/usb/usbd.h>
+#endif /* CONFIG_USB_DEVICE_STACK_NEXT */
+
+#ifdef CONFIG_BOOT_SERIAL_CDC_ACM
+#include "usbd_cdc_serial.h"
+#endif /* CONFIG_BOOT_SERIAL_CDC_ACM */
+
+#if defined(CONFIG_BOOT_SERIAL_UART) && defined(CONFIG_LOG_BACKEND_UART)
+#error "UART serial recovery and UART log backend cannot both be enabled"
+#endif
+
 #if CONFIG_MCUBOOT_CLEANUP_ARM_CORE
 #include <arm_cleanup.h>
 #endif
@@ -185,6 +197,21 @@ static void do_boot(struct boot_rsp *rsp)
     /* Disable the USB to prevent it from firing interrupts */
     usb_disable();
 #endif
+#ifdef CONFIG_USB_DEVICE_STACK_NEXT
+    {
+        int usbd_rc;
+
+        usbd_rc = usbd_disable(boot_usb_cdc_serial_get_context());
+
+        /* -EALREADY is expected on normal boot: USB was never enabled
+         * (lazy init -- only initialized when recovery is triggered).
+         * Any other error indicates a real problem.
+         */
+        if (usbd_rc != 0 && usbd_rc != -EALREADY) {
+            BOOT_LOG_WRN("USB disable failed: %d", usbd_rc);
+        }
+    }
+#endif
 #if CONFIG_MCUBOOT_CLEANUP_ARM_CORE
     cleanup_arm_interrupts(); /* Disable and acknowledge all interrupts */
 

boot/zephyr/sample.yaml

@@ -65,7 +65,7 @@ tests:
     platform_allow: nrf52840dongle/nrf52840
     extra_args:
       - EXTRA_CONF_FILE=./usb_cdc_acm_recovery.conf
-      - DTC_OVERLAY_FILE="./usb_cdc_acm.overlay;app.overlay"
+      - DTC_OVERLAY_FILE="./boards/nrf52840dongle_nrf52840_big.overlay;./usb_cdc_acm.overlay;app.overlay"
     extra_configs:
       - CONFIG_DEPRECATION_TEST=y
   sample.bootloader.mcuboot.usb_cdc_acm_recovery_log:

boot/zephyr/serial_adapter.c

@@ -20,7 +20,8 @@
 #include <string.h>
 #include <zephyr/kernel.h>
 #include "bootutil/bootutil_log.h"
-#include <zephyr/usb/usb_device.h>
+#include "mcuboot_config/mcuboot_config.h"
+#include <zephyr/usb/usbd.h>
 
 #if defined(CONFIG_BOOT_SERIAL_UART) && defined(CONFIG_UART_CONSOLE) && \
     (!DT_HAS_CHOSEN(zephyr_uart_mcumgr) ||                              \
@@ -40,6 +41,10 @@
        (0 or above)
 #endif
 
+#if defined(CONFIG_BOOT_SERIAL_CDC_ACM)
+#include "usbd_cdc_serial.h"
+#endif
+
 BOOT_LOG_MODULE_REGISTER(serial_adapter);
 
 /** @brief Console input representation
@@ -213,24 +218,10 @@ boot_uart_fifo_init(void)
 	uart_dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_console));
 #endif
 
-#elif defined(CONFIG_BOOT_SERIAL_CDC_ACM)
-        uart_dev = DEVICE_DT_GET_ONE(zephyr_cdc_acm_uart);
-#else
-#error No serial recovery device selected
-#endif
-
-
 	if (!device_is_ready(uart_dev)) {
 		return (-1);
 	}
 
-#if CONFIG_BOOT_SERIAL_CDC_ACM
-	int rc = usb_enable(NULL);
-	if (rc) {
-		return (-1);
-	}
-#endif
-
 	uart_irq_callback_set(uart_dev, boot_uart_fifo_callback);
 
 	/* Drain the fifo */
@@ -246,5 +237,41 @@ boot_uart_fifo_init(void)
 
 	uart_irq_rx_enable(uart_dev);
 
+#elif defined(CONFIG_BOOT_SERIAL_CDC_ACM)
+
+	int rc;
+
+	rc = boot_usb_cdc_serial_init();
+	if (rc) {
+		return (-1);
+	}
+
+	rc = usbd_enable(boot_usb_cdc_serial_get_context());
+	if (rc) {
+		return (-1);
+	}
+
+	/* Feed WDT while waiting for USB host to open the serial port.
+	 * Without this, the hardware watchdog fires before the serial
+	 * recovery loop (which feeds the WDT) is reached. */
+	while (k_sem_take(&boot_cdc_acm_ready, K_MSEC(5000)) != 0) {
+#if CONFIG_BOOT_WATCHDOG_FEED
+		MCUBOOT_WATCHDOG_FEED();
+#endif
+	}
+
+	uart_dev = DEVICE_DT_GET_ONE(zephyr_cdc_acm_uart);
+	if (!device_is_ready(uart_dev)) {
+		return (-1);
+	}
+
+	uart_irq_callback_set(uart_dev, boot_uart_fifo_callback);
+	cur = 0;
+	uart_irq_rx_enable(uart_dev);
+
+#else
+#error No serial recovery device selected
+#endif
+
 	return 0;
 }

boot/zephyr/usb_cdc_acm_log_recovery.conf

@@ -9,3 +9,7 @@ CONFIG_UART_LINE_CTRL=y
 # MCUBoot serial
 CONFIG_MCUBOOT_SERIAL=y
 CONFIG_BOOT_SERIAL_CDC_ACM=y
+CONFIG_BOOT_SERIAL_CDC_ACM_PRODUCT_STRING="MCUBOOT"
+CONFIG_USBD_MSG_DEFERRED_MODE=n
+CONFIG_USBD_BOS_SUPPORT=n
+CONFIG_USBD_VREQ_SUPPORT=n

boot/zephyr/usb_cdc_acm_recovery.conf

@@ -1,3 +1,8 @@
 CONFIG_MCUBOOT_SERIAL=y
 CONFIG_BOOT_SERIAL_CDC_ACM=y
 CONFIG_UART_CONSOLE=n
+
+CONFIG_BOOT_SERIAL_CDC_ACM_PRODUCT_STRING="MCUBOOT"
+CONFIG_USBD_MSG_DEFERRED_MODE=n
+CONFIG_USBD_BOS_SUPPORT=n
+CONFIG_USBD_VREQ_SUPPORT=n