core: pinmux: implement rough solution

While we prepare a cleaner solution, this patch allows back and forth between pinmuxes.
Tested on UNO Q with next patch in the series and this sketch

void loop() {
  Serial.begin(115200);
  Serial.println("helloooooo");
  delay(20);
  Serial.end();
  delay(20);
  pinMode(1, OUTPUT);
  digitalWrite(1, HIGH);
  delay(10);
  digitalWrite(1, LOW);
  delay(100);
  analogWrite(1, 33);
}

Pin 1 correctly prints the string, muxes as GPIo and then produces the required PWM

Author: facchinm

cores/arduino/zephyrCommon.cpp

@@ -7,6 +7,19 @@
 #include <Arduino.h>
 #include "zephyrInternal.h"
 
+// create an array of arduino_pins with functions to reinitialize pins if needed
+static const struct device *pinmux_array[DT_PROP_LEN(DT_PATH(zephyr_user), digital_pin_gpios)] = { nullptr };
+
+void _reinit_peripheral_if_needed(pin_size_t pin, const struct device *dev)
+{
+	if (pinmux_array[pin] != dev) {
+		pinmux_array[pin] = dev;
+		if (dev != NULL) {
+			dev->ops.init(dev);
+		}
+	}
+}
+
 static const struct gpio_dt_spec arduino_pins[] = {
 	DT_FOREACH_PROP_ELEM_SEP(
 	DT_PATH(zephyr_user), digital_pin_gpios, GPIO_DT_SPEC_GET_BY_IDX, (, ))};
@@ -209,6 +222,7 @@ void yield(void) {
  *  A high physical level will be interpreted as value 1
  */
 void pinMode(pin_size_t pinNumber, PinMode pinMode) {
+	_reinit_peripheral_if_needed(pinNumber, NULL);
 	if (pinMode == INPUT) { // input mode
 		gpio_pin_configure_dt(&arduino_pins[pinNumber], GPIO_INPUT | GPIO_ACTIVE_HIGH);
 	} else if (pinMode == INPUT_PULLUP) { // input with internal pull-up
@@ -320,6 +334,7 @@ void analogWrite(pin_size_t pinNumber, int value) {
 		return;
 	}
 
+	_reinit_peripheral_if_needed(pinNumber, arduino_pwm[idx].dev);
 	value = map(value, 0, 1 << _analog_write_resolution, 0, arduino_pwm[idx].period);
 
 	if (((uint32_t)value) > arduino_pwm[idx].period) {
@@ -343,6 +358,9 @@ void analogWrite(enum dacPins dacName, int value) {
 		return;
 	}
 
+	// TODO: add reverse map to find pin name from DAC* define
+	// In the meantime, consider A0 == DAC0
+	_reinit_peripheral_if_needed((pin_size_t)(dacName + A0), dac_dev);
 	dac_channel_setup(dac_dev, &dac_ch_cfg[dacName]);
 
 	const int max_dac_value = 1U << dac_ch_cfg[dacName].resolution;
@@ -393,6 +411,8 @@ int analogRead(pin_size_t pinNumber) {
 		return -ENOTSUP;
 	}
 
+	_reinit_peripheral_if_needed(pinNumber, arduino_adc[idx].dev);
+
 	err = adc_channel_setup(arduino_adc[idx].dev, &arduino_adc[idx].channel_cfg);
 	if (err < 0) {
 		return err;

cores/arduino/zephyrInternal.h

@@ -14,6 +14,7 @@ extern "C" {
 
 void enableInterrupt(pin_size_t);
 void disableInterrupt(pin_size_t);
+void _reinit_peripheral_if_needed(pin_size_t pin, const struct device *dev);
 
 #ifdef __cplusplus
 } // extern "C"

cores/arduino/zephyrSerial.cpp

@@ -59,6 +59,8 @@ void arduino::ZephyrSerial::begin(unsigned long baud, uint16_t conf) {
 		.flow_ctrl = UART_CFG_FLOW_CTRL_NONE,
 	};
 
+	uart->ops.init(uart);
+
 	uart_configure(uart, &config);
 	uart_irq_callback_user_data_set(uart, arduino::ZephyrSerial::IrqDispatch, this);
 	k_sem_take(&rx.sem, K_FOREVER);

cores/arduino/zephyrSerial.h

@@ -75,6 +75,9 @@ class ZephyrSerial : public HardwareSerial {
 	void flush();
 
 	void end() {
+		if (uart->ops.deinit) {
+			uart->ops.deinit(uart);
+		}
 	}
 
 	size_t write(const uint8_t *buffer, size_t size);

libraries/SPI/SPI.cpp

@@ -115,9 +115,13 @@ void arduino::ZephyrSPI::detachInterrupt() {
 }
 
 void arduino::ZephyrSPI::begin() {
+	spi_dev->ops.init(spi_dev);
 }
 
 void arduino::ZephyrSPI::end() {
+	if (spi_dev->ops.deinit) {
+		spi_dev->ops.deinit(spi_dev);
+	}
 }
 
 #if DT_NODE_HAS_PROP(DT_PATH(zephyr_user), spis)

libraries/Wire/Wire.cpp

@@ -54,6 +54,7 @@ arduino::ZephyrI2C::ZephyrI2C(const struct device *i2c) : i2c_dev(i2c), i2c_cfg(
 }
 
 void arduino::ZephyrI2C::begin() {
+	i2c_dev->ops.init(i2c_dev);
 }
 
 void arduino::ZephyrI2C::begin(uint8_t slaveAddr) {
@@ -70,6 +71,9 @@ void arduino::ZephyrI2C::end() {
 		i2c_target_unregister(i2c_dev, &i2c_cfg);
 		memset(&i2c_cfg, 0, sizeof(i2c_cfg));
 	}
+	if (i2c_dev->ops.deinit) {
+		i2c_dev->ops.deinit(i2c_dev);
+	}
 }
 
 void arduino::ZephyrI2C::setClock(uint32_t freq) {

loader/prj.conf

@@ -30,6 +30,8 @@ CONFIG_LLEXT_EDK_FORMAT_TAR_ZSTD=y
 
 CONFIG_GPIO=y
 CONFIG_PINCTRL=y
+CONFIG_PINCTRL_DYNAMIC=y
+CONFIG_DEVICE_DEINIT_SUPPORT=y
 CONFIG_I2C=y
 CONFIG_SPI=y