imx9 board_reset: boot reason from PX4 to bootloader

WDOG_B pin is unused in current HW design. Related configuration bits
(WDOG_B_CFG) from PMIC RESET_CTRL register are borrowed for stay in
bootloader boot reason delivery.

-stay in bootloader: WDOG_B_CFG value 11b
-boot normally: PMIC register power on value

Signed-off-by: Tero Salminen <[email protected]>

platforms/nuttx/src/px4/nxp/imx9/board_reset/board_reset.cpp

@@ -41,18 +41,38 @@
 #include <errno.h>
 #include <nuttx/board.h>
 #include <debug.h>
+#include "imx9_pmic.h"
 
 extern "C" void __start(void);
 
 static void board_reset_enter_bootloader()
 {
+	/* WDOG_B pin is unused in current HW design.
+	* Related configuration bits (WDOG_B_CFG) from PMIC RESET_CTRL
+	* register are borrowed for stay in bootloader reason delivery.
+	*
+	* stay in bootloader: WDOG_B_CFG 11b
+	*/
+
+	imx9_pmic_set_reset_ctrl(IMX9_PMIC_RESET_CTRL_DEFAULT |
+				 IMX9_PMIC_RESET_CTRL_WDOG_COLD_RESET_MASK);
+
 	/* Reset the whole SoC */
 
 	up_systemreset();
 }
 
 static void board_reset_enter_bootloader_and_continue_boot()
 {
+	/* WDOG_B pin is unused in current HW design.
+	* Related configuration bits (WDOG_B_CFG) from PMIC RESET_CTRL
+	* register are borrowed for stay in bootloader reason delivery.
+	*
+	* With PMIC register power on value system will boot normally.
+	*/
+
+	imx9_pmic_set_reset_ctrl(IMX9_PMIC_RESET_CTRL_DEFAULT);
+
 	/* Reset the whole SoC */
 
 	up_systemreset();