fix(uart): lp uart rx iomux pin was not working as expected

Introduced in 8818157e42
The workaround in the commit routes the signal to LP GPIO matrix first.
When uses LP IOMUX pin as UART RX, the signal did not bypass the matrix,
which caused the issue.

This commit adds rtc_gpio_iomux_input and rtc_gpio_iomux_output APIs
to align with existing GPIO driver APIs.

components/hal/esp32p4/include/hal/rtc_io_ll.h

@@ -85,11 +85,37 @@ static inline void rtcio_ll_matrix_out(int rtcio_num, uint32_t signal_idx, bool
     reg.func_out_sel = signal_idx;
     reg.out_inv_sel = out_inv;
     reg.oe_inv_sel = oen_inv;
+    reg.oe_sel = 0; // output enable signal controlled by peripheral
     LP_GPIO.func_out_sel_cfg[rtcio_num].val = reg.val;
 
     HAL_FORCE_MODIFY_U32_REG_FIELD(LP_GPIO.enable_w1ts, reg_gpio_enable_data_w1ts, BIT(rtcio_num));
 }
 
+/**
+  * @brief Configure peripheral signal input whether to bypass LP_GPIO matrix.
+  *
+  * @param signal_idx LP peripheral signal index.
+  * @param from_gpio_matrix True if not to bypass LP_GPIO matrix, otherwise False.
+  */
+static inline void rtcio_ll_set_input_signal_from(uint32_t signal_idx, bool from_gpio_matrix)
+{
+    LP_GPIO.func_in_sel_cfg[signal_idx].sig_in_sel = from_gpio_matrix;
+}
+
+/**
+  * @brief Configure the source of output enable signal for the pad (only takes effect if func sel is selected to be LP_GPIO).
+  *
+  * @param rtcio_num The index of rtcio. 0 ~ MAX(rtcio).
+  * @param ctrl_by_periph True if use output enable signal from peripheral, false if force the output enable signal to be sourced from bit n of LP_GPIO_ENABLE_REG
+  * @param oen_inv True if the output enable needs to be inverted, otherwise False.
+  */
+__attribute__((always_inline))
+static inline void rtcio_ll_set_output_enable_ctrl(int rtcio_num, bool ctrl_by_periph, bool oen_inv)
+{
+    LP_GPIO.func_out_sel_cfg[rtcio_num].oe_inv_sel = oen_inv;       // control valid only when using lp gpio matrix to route signal to the LP IO
+    LP_GPIO.func_out_sel_cfg[rtcio_num].oe_sel = !ctrl_by_periph;
+}
+
 /**
  * @brief Select a RTC IOMUX function for the RTC IO
  *

components/hal/include/hal/rtc_io_hal.h

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2015-2025 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2015-2026 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -199,6 +199,23 @@ void rtcio_hal_set_direction_in_sleep(int rtcio_num, rtc_gpio_mode_t mode);
  */
 #define rtcio_hal_iomux_func_sel(rtcio_num, func) rtcio_ll_iomux_func_sel(rtcio_num, func)
 
+/**
+  * @brief Set pad input to an LP peripheral signal through the LP(RTC) IOMUX
+  *
+  * @param rtcio_num The index of rtcio. 0 ~ SOC_RTCIO_PIN_COUNT.
+  * @param func The index number of the IOMUX function to be selected for the pin.
+  * @param signal_idx Peripheral signal index to input. One of the ``*_IN_IDX`` signals in ``soc/lp_gpio_sig_map.h``.
+  */
+void rtcio_hal_iomux_input(int rtcio_num, int func, uint32_t signal_idx);
+
+/**
+  * @brief Set LP peripheral output to an RTC IO pad through the LP(RTC) IOMUX
+  *
+  * @param rtcio_num The index of rtcio. 0 ~ SOC_RTCIO_PIN_COUNT.
+  * @param func The index number of the LP(RTC) IOMUX function to be selected for the pin
+  */
+void rtcio_hal_iomux_output(int rtcio_num, int func);
+
 #if SOC_LP_GPIO_MATRIX_SUPPORTED
 /**
  * Select RTC GPIO input to a signal

components/hal/rtc_io_hal.c

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2015-2023 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2015-2026 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -88,4 +88,19 @@ void rtcio_hal_isolate(int rtcio_num)
 }
 #endif
 
+void rtcio_hal_iomux_input(int rtcio_num, int func, uint32_t signal_idx)
+{
+    rtcio_ll_input_enable(rtcio_num);
+    rtcio_ll_iomux_func_sel(rtcio_num, func);
+#if SOC_LP_GPIO_MATRIX_SUPPORTED
+    rtcio_ll_set_input_signal_from(signal_idx, false);
+#endif
+}
+
+void rtcio_hal_iomux_output(int rtcio_num, int func)
+{
+    rtcio_ll_iomux_func_sel(rtcio_num, func);
+    // as long as the func sel is not RTC IO, the oe can only be controlled by the peripheral
+}
+
 #endif //SOC_RTCIO_INPUT_OUTPUT_SUPPORTED