boards: pjrc: Added Support for the Teensy CLI Tools soft reboot functionality

Kconfig.zephyr

@@ -1098,6 +1098,19 @@ config BOOTLOADER_BOSSA_ADAFRUIT_UF2
 
 endchoice
 
+config BOOTLOADER_TEENSY
+	bool "Teensy bootloader support"
+	depends on SOC_SERIES_IMXRT10XX
+	help
+	  Sets whether the teensy bootloader should be loaded when an baudrate change is send or not.
+
+config BOOTLOADER_TEENSY_DEVICE_NAME
+	string "Teensy CDC ACM device name"
+	depends on BOOTLOADER_TEENSY
+	default "USB CDC-ACM"
+	help
+	  Sets the CDC ACM port to watch for reboot commands.
+
 endmenu
 
 menu "Compatibility"

boards/pjrc/teensy4/CMakeLists.txt

@@ -11,4 +11,5 @@ if(CONFIG_NXP_IMXRT_BOOT_HEADER)
   zephyr_compile_definitions(BOARD_FLASH_SIZE=CONFIG_FLASH_SIZE*1024)
   zephyr_library_sources(flexspi_nor_config.c)
   zephyr_library_sources_ifdef(CONFIG_DEVICE_CONFIGURATION_DATA teensy4_sdram_ini_dcd.c)
+  zephyr_library_sources_ifdef(CONFIG_BOOTLOADER_TEENSY bootloader_teensy.c)
 endif()

boards/pjrc/teensy4/bootloader_teensy.c

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2025 Navimatix GmbH.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <soc.h>
+#include <zephyr/drivers/uart/cdc_acm.h>
+#include <zephyr/drivers/usb/usb_dc.h>
+#include <zephyr/init.h>
+#include <zephyr/usb/class/usb_cdc.h>
+#include <zephyr/logging/log.h>
+
+LOG_MODULE_REGISTER(reset, CONFIG_SOC_LOG_LEVEL);
+
+#define TEENSY_RESET_BAUDRATE 134
+#define TEENSY_RESET_COMMAND  "bkpt #251"
+#define TEENSY_VID 0x16c0
+#define TEENSY_PID 0x0483
+
+static void teensy_reset(const struct device *dev, uint32_t rate)
+{
+	if (rate != TEENSY_RESET_BAUDRATE) {
+		return;
+	}
+
+	/* The programmer set the baud rate to 134 baud.  Reset into the
+	 * bootloader.
+	 */
+	__ASM volatile(TEENSY_RESET_COMMAND);
+}
+
+void board_late_init_hook(void)
+{
+	const struct device *dev = device_get_binding(CONFIG_BOOTLOADER_TEENSY_DEVICE_NAME);
+
+	if (dev == NULL) {
+		LOG_ERR("Could not find reset signal device with name %s",
+			CONFIG_BOOTLOADER_TEENSY_DEVICE_NAME);
+		return;
+	}
+
+	if ((CONFIG_USB_DEVICE_VID != TEENSY_VID) || (CONFIG_USB_DEVICE_PID != TEENSY_PID)) {
+		LOG_ERR("Incorrect USB VID or PID. CONFIG_USB_DEVICE_VID should be 0x%x and "
+			"CONFIG_USB_DEVICE_PID should be 0x%x.",
+			TEENSY_VID, TEENSY_PID);
+		return;
+	}
+
+	cdc_acm_dte_rate_callback_set(dev, teensy_reset);
+}

scripts/west_commands/runners/teensy.py

@@ -13,12 +13,13 @@
 class TeensyBinaryRunner(ZephyrBinaryRunner):
     '''Runner front-end for teensy.'''
 
-    def __init__(self, cfg, mcu, teensy_loader):
+    def __init__(self, cfg, mcu, teensy_loader, flags):
         super().__init__(cfg)
 
         self.mcu_args = ['--mcu', mcu]
         self.teensy_loader = teensy_loader
         self.hex_name = cfg.hex_file
+        self.flags = flags
 
     @classmethod
     def name(cls):
@@ -30,12 +31,13 @@ def do_add_parser(cls, parser):
                             help='Teensy mcu target')
         parser.add_argument('--teensy', default='teensy_loader_cli',
                             help='path to teensy cli tool, default is teensy_loader_cli')
+        parser.add_argument('--flags', help='Flags for the teensy cli tool')
 
     @classmethod
     def do_create(cls, cfg, args):
         ret = TeensyBinaryRunner(
             cfg, args.mcu,
-            teensy_loader=args.teensy)
+            teensy_loader=args.teensy, flags=args.flags)
         return ret
 
     def do_run(self, command):
@@ -54,6 +56,9 @@ def flash(self):
                self.mcu_args +
                [fname])
 
+        if self.flags is not None:
+            cmd.append("-" + self.flags)
+
         self.logger.info(f'Flashing file: {fname}')
 
         try:

snippets/pjrc-teensy-bootloader/README.rst

@@ -0,0 +1,32 @@
+.. _snippet-pjrc-teensy-bootloader:
+
+PJRC Teensy Bootloader (pjrc-teensy-bootloader)
+###############################################
+
+.. code-block:: console
+
+   west build -S pjrc-teensy-bootloader [...]
+
+Overview
+********
+
+This snippet makes the nessecary configurations to allow flashing of Teensy 4
+based boards without triggering the reset pin. This is done via a CDC ACM UART.
+
+Requirements
+************
+
+A board that supports flashing via the teensy cli tools.
+
+A devicetree node with node label ``zephyr_udc0`` that points to an enabled USB
+device node with driver support. This should look roughly like this in
+:ref:`your devicetree <get-devicetree-outputs>`:
+
+.. code-block:: DTS
+
+   usb1: zephyr_udc0: usbd@402e0000 {
+      compatible = "nxp,ehci";
+        /* ... */
+   };
+
+The Teensy 4.0 and 4.1 boards have this node by default, but others might not.

snippets/pjrc-teensy-bootloader/pjrc-teensy-bootloader.conf

@@ -0,0 +1,9 @@
+CONFIG_BOOTLOADER_TEENSY=y
+CONFIG_USB_DEVICE_VID=0x16c0
+CONFIG_USB_DEVICE_PID=0x0483
+
+CONFIG_USB_DEVICE_STACK=y
+CONFIG_USB_CDC_ACM=y
+CONFIG_CDC_ACM_DTE_RATE_CALLBACK_SUPPORT=y
+CONFIG_USB_DEVICE_INITIALIZE_AT_BOOT=y
+CONFIG_BOARD_LATE_INIT_HOOK=y

snippets/pjrc-teensy-bootloader/pjrc-teensy-bootloader.overlay

@@ -0,0 +1,12 @@
+/*
+ * Copyright (c) 2025 Navimatix GmbH
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+&zephyr_udc0 {
+	snippet_pjrc_teensy_bootloader_uart {
+		compatible = "zephyr,cdc-acm-uart";
+		label = "USB CDC-ACM";
+	};
+};

snippets/pjrc-teensy-bootloader/snippet.yml

@@ -0,0 +1,4 @@
+name: pjrc-teensy-bootloader
+append:
+  EXTRA_CONF_FILE: pjrc-teensy-bootloader.conf
+  EXTRA_DTC_OVERLAY_FILE: pjrc-teensy-bootloader.overlay