don't use pad state to track if a pin is in use

this interferes with the desire to allow a pin to be a non-default
state when it "is reset"

Author: jepler

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

@@ -31,6 +31,8 @@
 
 #include "src/rp2_common/hardware_gpio/include/hardware/gpio.h"
 
+static uint32_t gpio_bank0_pin_claimed;
+
 #if CIRCUITPY_CYW43
 #include "bindings/cyw43/__init__.h"
 #include "pico/cyw43_arch.h"
@@ -76,6 +78,7 @@ void reset_pin_number(uint8_t pin_number) {
         return;
     }
 
+    gpio_bank0_pin_claimed &= ~(1 << pin_number);
     never_reset_pins &= ~(1 << pin_number);
 
     // We are very aggressive in shutting down the pad fully. Both pulls are
@@ -105,19 +108,20 @@ void claim_pin(const mcu_pin_obj_t *pin) {
     #if CIRCUITPY_CYW43
     if (pin->base.type == &cyw43_pin_type) {
         cyw_pin_claimed |= (1 << pin->number);
+        return;
     }
     #endif
-    // Nothing to do because all changes will set the GPIO settings.
+    if (pin->number >= NUM_BANK0_GPIOS) {
+        return;
+    }
+    gpio_bank0_pin_claimed |= (1 << pin->number);
 }
 
 bool pin_number_is_free(uint8_t pin_number) {
     if (pin_number >= NUM_BANK0_GPIOS) {
         return false;
     }
-
-    uint32_t pad_state = padsbank0_hw->io[pin_number];
-    return (pad_state & PADS_BANK0_GPIO0_IE_BITS) == 0 &&
-           (pad_state & PADS_BANK0_GPIO0_OD_BITS) != 0;
+    return !(gpio_bank0_pin_claimed & (1 << pin_number));
 }
 
 bool common_hal_mcu_pin_is_free(const mcu_pin_obj_t *pin) {