esp32/main: Add option for a board to hook code into startup sequence.

To do this the board must define MICROPY_BOARD_STARTUP, set
MICROPY_SOURCE_BOARD then define the new start-up code.

For example, in mpconfigboard.h:

    #define MICROPY_BOARD_STARTUP board_startup
    void board_startup(void);

in mpconfigboard.cmake:

    set(MICROPY_SOURCE_BOARD
        ${MICROPY_BOARD_DIR}/board.c
    )

and in a new board.c file in the board directory:

    #include "py/mpconfig.h"

    void board_startup(void) {
        boardctrl_startup();
        // extra custom startup
    }

This follows stm32's boardctrl facilities.
Signed-off-by: Damien George <damien@micropython.org>

ports/esp32/main.c

@@ -202,12 +202,20 @@ soft_reset_exit:
     goto soft_reset;
 }
 
-void app_main(void) {
+void boardctrl_startup(void) {
     esp_err_t ret = nvs_flash_init();
     if (ret == ESP_ERR_NVS_NO_FREE_PAGES || ret == ESP_ERR_NVS_NEW_VERSION_FOUND) {
         nvs_flash_erase();
         nvs_flash_init();
     }
+}
+
+void app_main(void) {
+    // Hook for a board to run code at start up.
+    // This defaults to initialising NVS.
+    MICROPY_BOARD_STARTUP();
+
+    // Create and transfer control to the MicroPython task.
     xTaskCreatePinnedToCore(mp_task, "mp_task", MP_TASK_STACK_SIZE / sizeof(StackType_t), NULL, MP_TASK_PRIORITY, &mp_main_task_handle, MP_TASK_COREID);
 }
 

ports/esp32/main/CMakeLists.txt

@@ -89,6 +89,7 @@ set(MICROPY_SOURCE_QSTR
     ${MICROPY_SOURCE_SHARED}
     ${MICROPY_SOURCE_LIB}
     ${MICROPY_SOURCE_PORT}
+    ${MICROPY_SOURCE_BOARD}
 )
 
 set(IDF_COMPONENTS
@@ -156,6 +157,7 @@ idf_component_register(
         ${MICROPY_SOURCE_LIB}
         ${MICROPY_SOURCE_DRIVERS}
         ${MICROPY_SOURCE_PORT}
+        ${MICROPY_SOURCE_BOARD}
     INCLUDE_DIRS
         ${MICROPY_INC_CORE}
         ${MICROPY_INC_USERMOD}

ports/esp32/mpconfigport.h

@@ -308,3 +308,9 @@ typedef long mp_off_t;
 #ifndef MICROPY_HW_ENABLE_MDNS_RESPONDER
 #define MICROPY_HW_ENABLE_MDNS_RESPONDER    (1)
 #endif
+
+#ifndef MICROPY_BOARD_STARTUP
+#define MICROPY_BOARD_STARTUP boardctrl_startup
+#endif
+
+void boardctrl_startup(void);