Add the ability for a port to gc things, collect pin change objects that way

Author: jepler

main.c

@@ -1111,6 +1111,8 @@ void gc_collect(void) {
     // have lost their references in the VM even though they are mounted.
     gc_collect_root((void **)&MP_STATE_VM(vfs_mount_table), sizeof(mp_vfs_mount_t) / sizeof(mp_uint_t));
 
+    port_gc_collect();
+
     background_callback_gc_collect();
 
     #if CIRCUITPY_ALARM
@@ -1143,6 +1145,10 @@ void gc_collect(void) {
     gc_collect_end();
 }
 
+// Ports may provide an implementation of this function if it is needed
+MP_WEAK void port_gc_collect() {
+}
+
 void NORETURN nlr_jump_fail(void *val) {
     reset_into_safe_mode(SAFE_MODE_NLR_JUMP_FAIL);
     while (true) {

ports/mimxrt10xx/common-hal/microcontroller/Pin.c

@@ -28,6 +28,8 @@
 #include "shared-bindings/microcontroller/__init__.h"
 #include "shared-bindings/microcontroller/Pin.h"
 
+#include "py/gc.h"
+
 STATIC bool claimed_pins[IOMUXC_SW_PAD_CTL_PAD_COUNT];
 STATIC bool never_reset_pins[IOMUXC_SW_PAD_CTL_PAD_COUNT];
 
@@ -147,6 +149,11 @@ typedef struct {
 
 volatile static pin_change_interrupt_data pcid[MP_ARRAY_SIZE(s_gpioBases)][32];
 
+// The 'data' pointers may be to gc objects, they must be kept alive.
+void pin_gc_collect() {
+    gc_collect_root((void **)&pcid, sizeof(pcid) / sizeof(void *));
+}
+
 void enable_pin_change_interrupt(const mcu_pin_obj_t *pin, gpio_change_interrupt_t func, void *data) {
     int instance = GPIO_GetInstance(pin->gpio);
     volatile pin_change_interrupt_data *pci = &pcid[instance][pin->number];

ports/mimxrt10xx/common-hal/microcontroller/Pin.h

@@ -48,5 +48,6 @@ extern bool mimxrt10xx_board_reset_pin_number(const mcu_pin_obj_t *pin);
 typedef void (gpio_change_interrupt_t)(void *data);
 void disable_pin_change_interrupt(const mcu_pin_obj_t *pin);
 void enable_pin_change_interrupt(const mcu_pin_obj_t *pin, gpio_change_interrupt_t func, void *data);
+void pin_gc_collect(void);
 
 #endif // MICROPY_INCLUDED_MIMXRT10XX_COMMON_HAL_MICROCONTROLLER_PIN_H

ports/mimxrt10xx/supervisor/port.c

@@ -555,6 +555,10 @@ void port_idle_until_interrupt(void) {
     common_hal_mcu_enable_interrupts();
 }
 
+void port_gc_collect(void) {
+    pin_gc_collect();
+}
+
 // Catch faults where the memory access violates MPU settings.
 void MemManage_Handler(void);
 __attribute__((used)) void PLACE_IN_ITCM(MemManage_Handler)(void) {

supervisor/port.h

@@ -128,4 +128,8 @@ void port_post_boot_py(bool heap_valid);
 // A default weak implementation is provided that does nothing.
 void port_boot_info(void);
 
+// Some ports want to mark additional pointers as gc roots.
+// A default weak implementation is provided that does nothing.
+void port_gc_collect(void);
+
 #endif  // MICROPY_INCLUDED_SUPERVISOR_PORT_H