stm32/modmachine: Allow boards to provide custom bootloader code.

And expose the machine_bootloader() C function so it can be used elsewhere.

ports/stm32/boardctrl.h

@@ -37,6 +37,10 @@
 #define MICROPY_BOARD_STARTUP powerctrl_check_enter_bootloader
 #endif
 
+#ifndef MICROPY_BOARD_ENTER_BOOTLOADER
+#define MICROPY_BOARD_ENTER_BOOTLOADER(nargs, args)
+#endif
+
 #ifndef MICROPY_BOARD_EARLY_INIT
 #define MICROPY_BOARD_EARLY_INIT()
 #endif

ports/stm32/boards/ARDUINO_PORTENTA_H7/mpconfigboard.h

@@ -38,7 +38,7 @@ void PORTENTA_board_startup(void);
 #define MICROPY_BOARD_EARLY_INIT    PORTENTA_board_early_init
 void PORTENTA_board_early_init(void);
 
-#define MICROPY_BOARD_ENTER_BOOTLOADER PORTENTA_board_enter_bootloader
+#define MICROPY_BOARD_ENTER_BOOTLOADER(nargs, args) PORTENTA_board_enter_bootloader()
 void PORTENTA_board_enter_bootloader(void);
 
 void PORTENTA_board_low_power(int mode);

ports/stm32/modmachine.c

@@ -46,6 +46,7 @@
 #include "gccollect.h"
 #include "irq.h"
 #include "powerctrl.h"
+#include "boardctrl.h"
 #include "pybthread.h"
 #include "rng.h"
 #include "storage.h"
@@ -270,7 +271,7 @@ STATIC mp_obj_t machine_soft_reset(void) {
 MP_DEFINE_CONST_FUN_OBJ_0(machine_soft_reset_obj, machine_soft_reset);
 
 // Activate the bootloader without BOOT* pins.
-STATIC NORETURN mp_obj_t machine_bootloader(size_t n_args, const mp_obj_t *args) {
+NORETURN mp_obj_t machine_bootloader(size_t n_args, const mp_obj_t *args) {
     #if MICROPY_HW_ENABLE_USB
     pyb_usb_dev_deinit();
     #endif
@@ -280,6 +281,8 @@ STATIC NORETURN mp_obj_t machine_bootloader(size_t n_args, const mp_obj_t *args)
 
     __disable_irq();
 
+    MICROPY_BOARD_ENTER_BOOTLOADER(n_args, args);
+
     #if MICROPY_HW_USES_BOOTLOADER
     if (n_args == 0 || !mp_obj_is_true(args[0])) {
         // By default, with no args given, we enter the custom bootloader (mboot)

ports/stm32/modmachine.h

@@ -36,6 +36,7 @@ extern const mp_obj_type_t machine_i2s_type;
 void machine_init(void);
 void machine_deinit(void);
 void machine_i2s_init0();
+NORETURN mp_obj_t machine_bootloader(size_t n_args, const mp_obj_t *args);
 
 MP_DECLARE_CONST_FUN_OBJ_VAR_BETWEEN(machine_info_obj);
 MP_DECLARE_CONST_FUN_OBJ_0(machine_unique_id_obj);