py/scheduler: Allow a port to specify attrs for mp_keyboard_interrupt.

Functions like mp_keyboard_interrupt() may need to be called from an IRQ
handler and may need to be in a special memory section, so provide a
generic wrapping macro for a port to do this.  The macro name is chosen to
be MICROPY_WRAP_<function name in uppercase> so that (in the future with
more wrappers) each function could potentially be handled separately.

py/mpconfig.h

@@ -1438,6 +1438,13 @@ typedef double mp_float_t;
 #define MICROPY_PORT_ROOT_POINTERS
 #endif
 
+/*****************************************************************************/
+/* Hooks for a port to wrap functions with attributes                        */
+
+#ifndef MICROPY_WRAP_MP_KEYBOARD_INTERRUPT
+#define MICROPY_WRAP_MP_KEYBOARD_INTERRUPT(f) f
+#endif
+
 /*****************************************************************************/
 /* Miscellaneous settings                                                    */
 

py/scheduler.c

@@ -29,7 +29,7 @@
 #include "py/runtime.h"
 
 #if MICROPY_KBD_EXCEPTION
-void mp_keyboard_interrupt(void) {
+void MICROPY_WRAP_MP_KEYBOARD_INTERRUPT(mp_keyboard_interrupt)(void) {
     MP_STATE_VM(mp_pending_exception) = MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_kbd_exception));
     #if MICROPY_ENABLE_SCHEDULER
     if (MP_STATE_VM(sched_state) == MP_SCHED_IDLE) {