[modem]: Add support for UARTs DMA mode

components/esp_modem/CMakeLists.txt

@@ -9,9 +9,10 @@ else()
     set(platform_srcs src/esp_modem_primitives_freertos.cpp
                       src/esp_modem_api_target.cpp
                       src/esp_modem_uart.cpp
+                      src/esp_modem_uart_dma.cpp
                       src/esp_modem_term_uart.cpp
                       src/esp_modem_netif.cpp)
-    set(dependencies driver esp_event esp_netif)
+    set(dependencies driver esp_event esp_netif esp_driver_uart)
 endif()
 
 

components/esp_modem/examples/modem_console/README.md

@@ -14,6 +14,32 @@ that sets up the DCE based on a custom module implemented in the `my_module_dce.
 `get_module_name()` method supplying a user defined name, but keeps all other commands the same as defined in the `GenericModule`
 class.
 
+### UART DMA Support
+
+This example now supports UART DMA for high-speed data transfers using the ESP-IDF UHCI driver. DMA mode is automatically enabled for ESP32-S3 targets by default, providing:
+
+- **Higher Throughput**: DMA handles data transfer without CPU intervention
+- **Better CPU Utilization**: CPU can perform other tasks during data transfer
+- **Lower Latency**: Reduced interrupt overhead for large transfers
+- **Efficient Memory Usage**: Direct memory access reduces copying
+
+#### Configuration Options
+
+- **Enable UART DMA Support**: `CONFIG_EXAMPLE_MODEM_UART_USE_DMA` (default: y for ESP32-S3)
+- **DMA Buffer Size**: `CONFIG_EXAMPLE_MODEM_UART_DMA_BUFFER_SIZE` (default: 8192 bytes)
+
+#### Performance Benefits
+
+DMA mode is most beneficial for:
+- High baud rates (> 500 kbps)
+- Large data transfers
+- Applications requiring high throughput
+
+Traditional UART mode is suitable for:
+- Low baud rates
+- Small, infrequent transfers
+- Power-sensitive applications
+
 ### USB DTE support
 
 For USB enabled targets (ESP32-S2, ESP32-S3, or ESP32-P4), it is possible to connect to the modem device via USB.

components/esp_modem/examples/modem_console/main/modem_console_main.cpp

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2022-2024 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2022-2025 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Unlicense OR CC0-1.0
  */
@@ -21,6 +21,7 @@
 #include "cxx_include/esp_modem_dte.hpp"
 #include "esp_modem_config.h"
 #include "cxx_include/esp_modem_api.hpp"
+#include "esp_modem_uart_dma.h"
 #include "esp_idf_version.h"
 #if defined(CONFIG_EXAMPLE_SERIAL_CONFIG_USB)
 #include "esp_modem_usb_config.h"
@@ -135,7 +136,23 @@ extern "C" void app_main(void)
     dte_config.task_stack_size = CONFIG_EXAMPLE_MODEM_UART_EVENT_TASK_STACK_SIZE;
     dte_config.task_priority = CONFIG_EXAMPLE_MODEM_UART_EVENT_TASK_PRIORITY;
     dte_config.dte_buffer_size = CONFIG_EXAMPLE_MODEM_UART_RX_BUFFER_SIZE / 2;
+
+    // Configure DMA options if enabled
+#ifdef CONFIG_EXAMPLE_MODEM_UART_USE_DMA
+    dte_config.uart_config.use_dma = true;
+    dte_config.uart_config.dma_buffer_size = CONFIG_EXAMPLE_MODEM_UART_DMA_BUFFER_SIZE;
+    ESP_LOGI(TAG, "UART DMA enabled with buffer size: %zu", dte_config.uart_config.dma_buffer_size);
+#else
+    dte_config.uart_config.use_dma = false;
+    ESP_LOGI(TAG, "UART DMA disabled, using traditional UART mode");
+#endif
+
+    // Create DTE with appropriate terminal type
+#ifdef CONFIG_EXAMPLE_MODEM_UART_USE_DMA
+    auto uart_dte = create_uart_dma_dte(&dte_config);
+#else
     auto uart_dte = create_uart_dte(&dte_config);
+#endif
 
 #if defined(CONFIG_EXAMPLE_MODEM_DEVICE_SHINY)
     ESP_LOGI(TAG, "Initializing esp_modem for the SHINY module...");

components/esp_modem/examples/modem_console/sdkconfig.defaults

@@ -5,3 +5,7 @@ CONFIG_ESP_MAIN_TASK_STACK_SIZE=7168
 CONFIG_LWIP_PPP_SUPPORT=y
 # CONFIG_LWIP_PPP_ENABLE_IPV6 is not set
 CONFIG_LWIP_PPP_PAP_SUPPORT=y
+
+# Enable UART DMA by default for ESP32-S3
+CONFIG_EXAMPLE_MODEM_UART_USE_DMA=y
+CONFIG_EXAMPLE_MODEM_UART_DMA_BUFFER_SIZE=8192

components/esp_modem/include/cxx_include/esp_modem_api.hpp

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2021-2025 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -40,6 +40,15 @@ using dte_config = ::esp_modem_dte_config;
  */
 std::shared_ptr<DTE> create_uart_dte(const dte_config *config);
 
+/**
+ * @brief Create UART DTE with DMA support
+ * @param config DTE configuration
+ * @return shared ptr to DTE on success
+ *         nullptr on failure (either due to insufficient memory or wrong dte configuration)
+ *         if exceptions are disabled the API abort()'s on error
+ */
+std::shared_ptr<DTE> create_uart_dma_dte(const dte_config *config);
+
 /**
  * @brief Create VFS DTE
  * @param config DTE configuration

components/esp_modem/include/esp_modem_config.h

@@ -51,6 +51,8 @@ struct esp_modem_uart_term_config {
     int rx_buffer_size;             /*!< UART RX Buffer Size */
     int tx_buffer_size;             /*!< UART TX Buffer Size */
     int event_queue_size;           /*!< UART Event Queue Size, set to 0 if no event queue needed */
+    bool use_dma;                   /*!< Enable UHCI DMA for high-speed transfers */
+    size_t dma_buffer_size;         /*!< DMA buffer size for UHCI transfers */
 };
 
 // Forward declare the resource struct
@@ -114,6 +116,8 @@ struct esp_modem_dte_config {
             .rx_buffer_size = 4096,                 \
             .tx_buffer_size = 512,                  \
             .event_queue_size = 30,                 \
+            .use_dma = false,                       \
+            .dma_buffer_size = 8192,               \
        },                                           \
     }
 

components/esp_modem/include/esp_modem_uart_dma.h

@@ -0,0 +1,43 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2025 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#pragma once
+
+#include "esp_modem_config.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Create UART terminal with DMA support
+ *
+ * This function creates a UART terminal that can use UHCI DMA for high-speed
+ * data transfers. The DMA mode is enabled when the `use_dma` flag is set to true
+ * in the configuration.
+ *
+ * @param config Configuration structure for the UART terminal
+ * @return Pointer to the created terminal, or NULL on failure
+ */
+void* esp_modem_uart_dma_terminal_create(const esp_modem_dte_config *config);
+
+/**
+ * @brief Create UART terminal with DMA support (C++ interface)
+ *
+ * This is the C++ interface for creating a UART terminal with DMA support.
+ * It returns a std::unique_ptr<Terminal> for automatic memory management.
+ *
+ * @param config Configuration structure for the UART terminal
+ * @return std::unique_ptr<Terminal> for the created terminal
+ */
+#ifdef __cplusplus
+#include "cxx_include/esp_modem_dte.hpp"
+std::unique_ptr<esp_modem::Terminal> create_uart_dma_terminal(const esp_modem_dte_config *config);
+#endif
+
+#ifdef __cplusplus
+}
+#endif

components/esp_modem/src/esp_modem_api_target.cpp

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2021-2025 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -13,6 +13,7 @@
 #include "cxx_include/esp_modem_dce_factory.hpp"
 #include "esp_modem_config.h"
 #include "exception_stub.hpp"
+#include "esp_modem_uart_dma.h"
 
 namespace esp_modem {
 
@@ -28,4 +29,12 @@ std::shared_ptr<DTE> create_uart_dte(const dte_config *config)
     )
 }
 
+std::shared_ptr<DTE> create_uart_dma_dte(const dte_config *config)
+{
+    TRY_CATCH_RET_NULL(
+        auto term = create_uart_dma_terminal(config);
+        return std::make_shared<DTE>(config, std::move(term));
+    )
+}
+
 } // namespace esp_modem