feat(uart): fixes loopback function after IDF changes

IDF 5.4.1 has added a new function called uart_release_pin() that is called whenever new pins are set or when uart driver is deleted.

This has a side effect that causes RX pin to never work again with the loopback function. Other changes also have removed some GPIO setup that was necessary for the GPIO loopback mode work.

The PR forces a full RX Pin setup in order to make it work in GPIO Matrix with Loopback TX Signal

Author: SuGlider

cores/esp32/esp32-hal-uart.c

@@ -35,7 +35,7 @@
 
 #include "driver/rtc_io.h"
 #include "driver/lp_io.h"
-#include "soc/uart_periph.h"
+#include "soc/uart_pins.h"
 #include "esp_private/uart_share_hw_ctrl.h"
 
 static int s_uart_debug_nr = 0;         // UART number for debug output
@@ -1391,7 +1391,7 @@ unsigned long uartDetectBaudrate(uart_t *uart) {
     This is intended to make an internal loopback connection using IOMUX
     The function uart_internal_loopback() shall be used right after Arduino Serial.begin(...)
     This code "replaces" the physical wiring for connecting TX <--> RX in a loopback
-*/
+
 
 // gets the right TX or RX SIGNAL, based on the UART number from gpio_sig_map.h
 #ifdef CONFIG_IDF_TARGET_ESP32P4
@@ -1416,6 +1416,7 @@ unsigned long uartDetectBaudrate(uart_t *uart) {
 #define UART_RX_SIGNAL(uartNumber) (uartNumber == UART_NUM_0 ? U0RXD_IN_IDX : U1RXD_IN_IDX)
 #endif
 #endif  // ifdef CONFIG_IDF_TARGET_ESP32P4
+*/
 
 /*
    This function internally binds defined UARTs TX signal with defined RX pin of any UART (same or different).
@@ -1427,7 +1428,12 @@ void uart_internal_loopback(uint8_t uartNum, int8_t rxPin) {
     log_e("UART%d is not supported for loopback or RX pin %d is invalid.", uartNum, rxPin);
     return;
   }
-  esp_rom_gpio_connect_out_signal(rxPin, UART_TX_SIGNAL(uartNum), false, false);
+  // forces rxPin to use GPIO Matrix and setup the pin to receive UART TX Signal - IDF 5.4.1 Change with uart_release_pin()
+  gpio_func_sel((gpio_num_t) rxPin, PIN_FUNC_GPIO);
+  gpio_pullup_en((gpio_num_t) rxPin);
+  gpio_input_enable((gpio_num_t) rxPin);
+  esp_rom_gpio_connect_in_signal(rxPin, uart_periph_signal[uartNum].pins[SOC_UART_RX_PIN_IDX].signal, false);  
+  esp_rom_gpio_connect_out_signal(rxPin, uart_periph_signal[uartNum].pins[SOC_UART_TX_PIN_IDX].signal, false, false);
 }
 
 /*