feat(modem): Add support for pausing netif

Closes #699

components/esp_modem/Kconfig

@@ -85,4 +85,11 @@ menu "esp-modem"
             mode more robust for some devices (e.g. Quectel), but might cause
             trouble for other devices (e.g. SIMCOM).
 
+    config ESP_MODEM_ADD_DEBUG_LOGS
+        bool "Add UART Tx/Rx logs"
+        default n
+        help
+            If enabled, the library dumps all transmitted and received data.
+            This option is only used for debugging.
+
 endmenu

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

@@ -385,6 +385,17 @@ extern "C" void app_main(void)
         return 0;
     });
 #endif
+    const ConsoleCommand PauseNetwork("pause_net", "toggle network pause", no_args, [&](ConsoleCommand * c) {
+        static int cnt = 0;
+        if (++cnt % 2) {
+            ESP_LOGI(TAG, "Pausing netif");
+            dce->pause_netif(true);
+        } else {
+            ESP_LOGI(TAG, "Unpausing netif");
+            dce->pause_netif(false);
+        }
+        return 0;
+    });
 
     const struct SetApn {
         SetApn(): apn(STR1, nullptr, nullptr, "<apn>", "APN (Access Point Name)") {}

components/esp_modem/include/cxx_include/esp_modem_dce.hpp

@@ -103,6 +103,28 @@ class DCE_T {
     }
 #endif
 
+    /**
+     * @brief Pauses/Unpauses network temporarily
+     * @param do_pause true to pause, false to unpause
+     * @param force true to ignore command failures and continue
+     * @return command_result of the underlying commands
+     */
+    command_result pause_netif(bool do_pause, bool force = false)
+    {
+        command_result result;
+        if (do_pause) {
+            netif.pause();
+            dte->set_command_callbacks();
+            result = device->set_command_mode();
+        } else {
+            result = device->resume_data_mode();
+            if (result == command_result::OK || force) {
+                netif.resume();
+            }
+        }
+        return result;
+    }
+
 protected:
     std::shared_ptr<DTE> dte;
     std::shared_ptr<SpecificModule> device;

components/esp_modem/include/cxx_include/esp_modem_dte.hpp

@@ -145,6 +145,12 @@ class DTE : public CommandableIf {
      */
     bool recover();
 
+    /**
+     * @brief Set internal command callbacks to the underlying terminal.
+     * Here we capture command replies to be processed by supplied command callbacks in  struct command_cb.
+     */
+    void set_command_callbacks();
+
 protected:
     /**
      * @brief Allows for locking the DTE
@@ -204,12 +210,6 @@ class DTE : public CommandableIf {
     } inflatable;
 #endif // CONFIG_ESP_MODEM_USE_INFLATABLE_BUFFER_IF_NEEDED
 
-    /**
-     * @brief Set internal command callbacks to the underlying terminal.
-     * Here we capture command replies to be processed by supplied command callbacks in  struct command_cb.
-     */
-    void set_command_callbacks();
-
     /**
      * @brief This abstracts command callback processing and implements its locking, signaling of completion and timeouts.
      */

components/esp_modem/include/cxx_include/esp_modem_netif.hpp

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2021-2024 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -54,6 +54,16 @@ class Netif {
      */
     void stop();
 
+    /**
+     * @brief Pause the network interface
+     */
+    void pause();
+
+    /**
+     * @brief Resume the network interface
+     */
+    void resume();
+
     void receive(uint8_t *data, size_t len);
 
 private:

components/esp_modem/src/esp_modem_netif.cpp

@@ -99,6 +99,20 @@ void Netif::stop()
     signal.clear(PPP_STARTED);
 }
 
+void Netif::resume()
+{
+    ppp_dte->set_read_cb([this](uint8_t *data, size_t len) -> bool {
+        receive(data, len);
+        return true;
+    });
+    signal.set(PPP_STARTED);
+}
+
+void Netif::pause()
+{
+    signal.clear(PPP_STARTED);
+}
+
 Netif::~Netif()
 {
     if (signal.is_any(PPP_STARTED)) {

components/esp_modem/src/esp_modem_uart.cpp

@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
+ * SPDX-FileCopyrightText: 2021-2024 Espressif Systems (Shanghai) CO LTD
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -176,13 +176,20 @@ int UartTerminal::read(uint8_t *data, size_t len)
     uart_get_buffered_data_len(uart.port, &length);
     length = std::min(len, length);
     if (length > 0) {
-        return uart_read_bytes(uart.port, data, length, portMAX_DELAY);
+        int read_len = uart_read_bytes(uart.port, data, length, portMAX_DELAY);
+#if CONFIG_ESP_MODEM_ADD_DEBUG_LOGS
+        ESP_LOG_BUFFER_HEXDUMP("uart-rx", data, read_len, ESP_LOG_DEBUG);
+#endif
+        return read_len;
     }
     return 0;
 }
 
 int UartTerminal::write(uint8_t *data, size_t len)
 {
+#if CONFIG_ESP_MODEM_ADD_DEBUG_LOGS
+    ESP_LOG_BUFFER_HEXDUMP("uart-tx", data, len, ESP_LOG_DEBUG);
+#endif
     return uart_write_bytes_compat(uart.port, data, len);
 }