uart: uart_set_pin function will now use IOMUX whenever possible

By using IOMUX instead of GPIO Matrix for UART, it is now possible
on ESP32 boards to use the UART as a wake up source even if it is
not used as a console.
For other boards where this issue was not present, using IOMUX has
the advantage to be faster than using GPIO matrix, so a highest
baudrate can be used

components/soc/esp32c3/include/soc/io_mux_reg.h

@@ -124,9 +124,6 @@
 #define GPIO_PAD_PULLDOWN(num) do{PIN_PULLUP_DIS(IOMUX_REG_GPIO##num);PIN_PULLDWN_EN(IOMUX_REG_GPIO##num);}while(0)
 #define GPIO_PAD_SET_DRV(num, drv) PIN_SET_DRV(IOMUX_REG_GPIO##num, drv)
 
-#define U0RXD_GPIO_NUM 20
-#define U0TXD_GPIO_NUM 21
-
 #define SPI_HD_GPIO_NUM  12
 #define SPI_WP_GPIO_NUM  13
 #define SPI_CS0_GPIO_NUM 14

components/soc/esp32c3/include/soc/soc_caps.h

@@ -240,7 +240,6 @@
 /*-------------------------- UART CAPS ---------------------------------------*/
 // ESP32-C3 has 2 UARTs
 #define SOC_UART_NUM                (2)
-
 #define SOC_UART_FIFO_LEN           (128)      /*!< The UART hardware FIFO length */
 #define SOC_UART_BITRATE_MAX        (5000000)  /*!< Max bit rate supported by UART */
 

components/soc/esp32c3/include/soc/uart_pins.h

@@ -0,0 +1,44 @@
+// Copyright 2015-2021 Espressif Systems (Shanghai) PTE LTD
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+
+#include "soc/io_mux_reg.h"
+
+/* Specify the number of pins for UART */
+#define SOC_UART_PINS_COUNT  (4)
+
+/* Specify the GPIO pin number for each UART signal in the IOMUX */
+#define U0RXD_GPIO_NUM 20
+#define U0TXD_GPIO_NUM 21
+#define U0RTS_GPIO_NUM (-1)
+#define U0CTS_GPIO_NUM (-1)
+
+#define U1RXD_GPIO_NUM (-1)
+#define U1TXD_GPIO_NUM (-1)
+#define U1RTS_GPIO_NUM (-1)
+#define U1CTS_GPIO_NUM (-1)
+
+/* The following defines are necessary for reconfiguring the UART
+ * to use IOMUX, at runtime. */
+#define U0TXD_MUX_FUNC  (FUNC_U0TXD_U0TXD)
+#define U0RXD_MUX_FUNC  (FUNC_U0RXD_U0RXD)
+/* No func for the following pins, they shall not be used */
+#define U0RTS_MUX_FUNC  (-1)
+#define U0CTS_MUX_FUNC  (-1)
+/* Same goes for UART1 */
+#define U1TXD_MUX_FUNC  (-1)
+#define U1RXD_MUX_FUNC  (-1)
+#define U1RTS_MUX_FUNC  (-1)
+#define U1CTS_MUX_FUNC  (-1)

components/soc/esp32c3/uart_periph.c

@@ -18,20 +18,71 @@
  Bunch of constants for every UART peripheral: GPIO signals, irqs, hw addr of registers etc
 */
 const uart_signal_conn_t uart_periph_signal[SOC_UART_NUM] = {
-    {
-        .tx_sig = U0TXD_OUT_IDX,
-        .rx_sig = U0RXD_IN_IDX,
-        .rts_sig = U0RTS_OUT_IDX,
-        .cts_sig = U0CTS_IN_IDX,
+   {
+        .pins = {
+            [SOC_UART_TX_PIN_IDX] = {
+                .default_gpio = U0TXD_GPIO_NUM,
+                .iomux_func = U0TXD_MUX_FUNC,
+                .input = 0,
+                .signal = U0TXD_OUT_IDX,
+            },
+
+            [SOC_UART_RX_PIN_IDX] = {
+                .default_gpio = U0RXD_GPIO_NUM,
+                .iomux_func = U0RXD_MUX_FUNC,
+                .input = 1,
+                .signal = U0RXD_IN_IDX,
+            },
+
+            [SOC_UART_RTS_PIN_IDX] = {
+                .default_gpio = U0RTS_GPIO_NUM,
+                .iomux_func = U0RTS_MUX_FUNC,
+                .input = 0,
+                .signal = U0RTS_OUT_IDX,
+            },
+
+            [SOC_UART_CTS_PIN_IDX] = {
+                .default_gpio = U0CTS_GPIO_NUM,
+                .iomux_func = U0CTS_MUX_FUNC,
+                .input = 1,
+                .signal = U0CTS_IN_IDX,
+            }
+        },
         .irq = ETS_UART0_INTR_SOURCE,
         .module = PERIPH_UART0_MODULE,
     },
+
     {
-        .tx_sig = U1TXD_OUT_IDX,
-        .rx_sig = U1RXD_IN_IDX,
-        .rts_sig = U1RTS_OUT_IDX,
-        .cts_sig = U1CTS_IN_IDX,
+        .pins = {
+            [SOC_UART_TX_PIN_IDX] = {
+                .default_gpio = U1TXD_GPIO_NUM,
+                .iomux_func = U1TXD_MUX_FUNC,
+                .input = 0,
+                .signal = U1TXD_OUT_IDX,
+            },
+
+            [SOC_UART_RX_PIN_IDX] = {
+                .default_gpio = U1RXD_GPIO_NUM,
+                .iomux_func = U1RXD_MUX_FUNC,
+                .input = 1,
+                .signal = U1RXD_IN_IDX,
+            },
+
+            [SOC_UART_RTS_PIN_IDX] = {
+                .default_gpio = U1RTS_GPIO_NUM,
+                .iomux_func = U1RTS_MUX_FUNC,
+                .input = 0,
+                .signal = U1RTS_OUT_IDX,
+            },
+
+            [SOC_UART_CTS_PIN_IDX] = {
+                .default_gpio = U1CTS_GPIO_NUM,
+                .iomux_func = U1CTS_MUX_FUNC,
+                .input = 1,
+                .signal = U1CTS_IN_IDX,
+            },
+        },
         .irq = ETS_UART1_INTR_SOURCE,
         .module = PERIPH_UART1_MODULE,
-    }
+    },
 };