feat(eppp): Add support for transport via Ethernet link

components/eppp_link/CMakeLists.txt

@@ -1,3 +1,22 @@
-idf_component_register(SRCS eppp_link.c eppp_sdio_slave.c eppp_sdio_host.c
+if("${IDF_VERSION_MAJOR}.${IDF_VERSION_MINOR}" VERSION_GREATER "5.3")
+    set(driver_deps esp_driver_gpio esp_driver_spi)
+else()
+    set(driver_deps driver)
+endif()
+
+if(CONFIG_EPPP_LINK_DEVICE_ETH)
+    set(transport_src eppp_eth.c)
+endif()
+
+if(CONFIG_EPPP_LINK_DEVICE_SDIO)
+    set(transport_src eppp_sdio_slave.c eppp_sdio_host.c)
+endif()
+
+idf_component_register(SRCS eppp_link.c ${transport_src}
                     INCLUDE_DIRS "include"
-                    PRIV_REQUIRES esp_netif esp_driver_spi esp_driver_gpio esp_timer driver)
+                    PRIV_REQUIRES esp_netif esp_timer esp_eth ${driver_deps})
+
+if(CONFIG_EPPP_LINK_DEVICE_ETH)
+    idf_component_get_property(ethernet_init espressif__ethernet_init COMPONENT_LIB)
+    target_link_libraries(${COMPONENT_LIB} PRIVATE ${ethernet_init})
+endif()

components/eppp_link/Kconfig

@@ -28,6 +28,16 @@ menu "eppp_link"
             help
                 Use SDIO.
 
+        config EPPP_LINK_DEVICE_ETH
+            bool "Ethernet"
+            depends on SOC_EMAC_SUPPORTED
+            help
+                Use Ethernet.
+                This transport could employ a full fledged Ethernet connection
+                between two EPPP nodes via standard Ethernet cable.
+                It could be also effectively connected directly on PCB, EMAC to EMAC,
+                without any Ethernet PHY chips (using eth_dummy_phy driver).
+
     endchoice
 
     config EPPP_LINK_CONN_MAX_RETRY
@@ -67,4 +77,14 @@ menu "eppp_link"
 
     endchoice
 
+    config EPPP_LINK_ETHERNET_OUR_ADDRESS
+        string "MAC address our local node"
+        default "06:00:00:00:00:01"
+        depends on EPPP_LINK_DEVICE_ETH
+
+    config EPPP_LINK_ETHERNET_THEIR_ADDRESS
+        string "MAC address the remote node"
+        default "06:00:00:00:00:02"
+        depends on EPPP_LINK_DEVICE_ETH
+
 endmenu

components/eppp_link/README.md

@@ -11,12 +11,12 @@ We usually call this node a SLAVE microcontroller. The "HOST" microcontroller ru
 brings in the WiFi connectivity from the "SLAVE" microcontroller.
 
 ```
-             SLAVE micro                                  HOST micro
-    \|/  +----------------+                           +----------------+
-     |   |                |          serial line      |                |
-     +---+ WiFi NAT PPPoS |=== UART / SPI / SDIO =====| PPPoS client   |
-         |        (server)|                           |                |
-         +----------------+                           +----------------+
+             SLAVE micro                                     HOST micro
+    \|/  +----------------+                               +----------------+
+     |   |                |       (serial) line           |                |
+     +---+ WiFi NAT PPPoS |=== UART / SPI / SDIO / ETH ===| PPPoS client   |
+         |        (server)|                               |                |
+         +----------------+                               +----------------+
 ```
 
 ## API
@@ -55,3 +55,9 @@ Tested with WiFi-NAPT example
 
 * TCP - 9Mbits/s
 * UDP - 11Mbits/s
+
+### Ethernet
+
+- Internal EMAC with real PHY chip
+    * TCP - 5Mbits/s
+    * UDP - 8Mbits/s

components/eppp_link/eppp_eth.c

@@ -0,0 +1,119 @@
+/*
+ * SPDX-FileCopyrightText: 2024-2025 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include <string.h>
+#include <stdint.h>
+#include <inttypes.h>
+#include "esp_log.h"
+#include "esp_netif.h"
+#include "esp_check.h"
+#include "esp_event.h"
+#include "esp_mac.h"
+#include "eppp_link.h"
+#include "eppp_transport.h"
+#include "esp_eth_driver.h"
+#include "ethernet_init.h"
+#include "esp_eth_spec.h"
+
+typedef struct header {
+    uint8_t dst[ETH_ADDR_LEN];
+    uint8_t src[ETH_ADDR_LEN];
+    uint16_t len;
+} __attribute__((packed)) header_t;
+
+static const char *TAG = "eppp_ethernet";
+static bool s_is_connected = false;
+static esp_eth_handle_t *s_eth_handles = NULL;
+static uint8_t s_out_buffer[ETH_MAX_PACKET_SIZE];
+static uint8_t s_their_mac[ETH_ADDR_LEN];
+static uint8_t s_our_mac[ETH_ADDR_LEN];
+
+static void event_handler(void *arg, esp_event_base_t event_base,
+                          int32_t event_id, void *event_data)
+{
+    switch (event_id) {
+    case ETHERNET_EVENT_CONNECTED:
+        ESP_LOGI(TAG, "Ethernet Link Up");
+        s_is_connected = true;
+        break;
+    case ETHERNET_EVENT_DISCONNECTED:
+        ESP_LOGI(TAG, "Ethernet Link Down");
+        s_is_connected = false;
+        break;
+    case ETHERNET_EVENT_START:
+        ESP_LOGI(TAG, "Ethernet Started");
+        break;
+    case ETHERNET_EVENT_STOP:
+        ESP_LOGI(TAG, "Ethernet Stopped");
+        break;
+    default:
+        break;
+    }
+}
+
+static esp_err_t receive(esp_eth_handle_t h, uint8_t *buffer, uint32_t len, void *netif)
+{
+    header_t *head = (header_t *)buffer;
+    size_t packet_len = head->len;
+    if (len >= packet_len) {
+        esp_err_t ret = esp_netif_receive(netif, buffer + ETH_HEADER_LEN, packet_len, NULL);
+        free(buffer);
+        return ret;
+    }
+    return ESP_FAIL;
+}
+
+__attribute__((weak)) esp_err_t eppp_transport_ethernet_init(esp_eth_handle_t *handle_array[])
+{
+    uint8_t eth_port_cnt = 0;
+    ESP_RETURN_ON_ERROR(ethernet_init_all(handle_array, &eth_port_cnt), TAG, "Failed to init common eth drivers");
+    ESP_RETURN_ON_FALSE(eth_port_cnt == 1, ESP_ERR_INVALID_ARG, TAG, "multiple Ethernet devices detected, please init only one");
+    return ESP_OK;
+}
+
+__attribute__((weak)) void eppp_transport_ethernet_deinit(esp_eth_handle_t *handle_array)
+{
+    ethernet_deinit_all(s_eth_handles);
+}
+
+
+esp_err_t eppp_transport_init(eppp_config_t *config, esp_netif_t *esp_netif)
+{
+    ESP_RETURN_ON_ERROR(eppp_transport_ethernet_init(&s_eth_handles), TAG, "Failed to initialize Ethernet driver");
+    ESP_RETURN_ON_ERROR(esp_eth_update_input_path(s_eth_handles[0], receive, esp_netif), TAG, "Failed to set Ethernet Rx callback");
+    sscanf(CONFIG_EPPP_LINK_ETHERNET_OUR_ADDRESS, "%2" PRIu8 ":%2" PRIu8 ":%2" PRIi8 ":%2" PRIu8 ":%2" PRIu8 ":%2" PRIu8,
+           &s_our_mac[0], &s_our_mac[1], &s_our_mac[2], &s_our_mac[3], &s_our_mac[4], &s_our_mac[5]);
+
+    sscanf(CONFIG_EPPP_LINK_ETHERNET_THEIR_ADDRESS, "%2" PRIu8 ":%2" PRIu8 ":%2" PRIi8 ":%2" PRIu8 ":%2" PRIu8 ":%2" PRIu8,
+           &s_their_mac[0], &s_their_mac[1], &s_their_mac[2], &s_their_mac[3], &s_their_mac[4], &s_their_mac[5]);
+    esp_eth_ioctl(s_eth_handles[0], ETH_CMD_S_MAC_ADDR, s_our_mac);
+    ESP_RETURN_ON_ERROR(esp_event_handler_register(ETH_EVENT, ESP_EVENT_ANY_ID, event_handler, NULL), TAG, "Failed to register Ethernet handlers");
+    ESP_RETURN_ON_ERROR(esp_eth_start(s_eth_handles[0]), TAG, "Failed to start Ethernet driver");
+    return ESP_OK;
+}
+
+void eppp_transport_deinit(void)
+{
+    esp_eth_stop(s_eth_handles[0]);
+    eppp_transport_ethernet_deinit(s_eth_handles);
+}
+
+esp_err_t eppp_transport_tx(void *h, void *buffer, size_t len)
+{
+    if (!s_is_connected) {
+        return ESP_FAIL;
+    }
+    // setup Ethernet header
+    header_t *head = (header_t *)s_out_buffer;
+    memcpy(head->dst, s_their_mac, ETH_ADDR_LEN);
+    memcpy(head->src, s_our_mac, ETH_ADDR_LEN);
+    head->len = len;
+    // support only payloads with len <=  ETH_MAX_PAYLOAD_LEN
+    if (len > ETH_MAX_PAYLOAD_LEN) {
+        return ESP_FAIL;
+    }
+    memcpy(s_out_buffer + ETH_HEADER_LEN, buffer, len);
+    return esp_eth_transmit(s_eth_handles[0], s_out_buffer, len + ETH_HEADER_LEN);
+}

components/eppp_link/eppp_link.c

@@ -12,7 +12,7 @@
 #include "esp_event.h"
 #include "esp_netif_ppp.h"
 #include "eppp_link.h"
-#include "esp_serial_slave_link/essl_sdio.h"
+#include "eppp_transport.h"
 
 #if CONFIG_EPPP_LINK_DEVICE_SPI
 #include "driver/spi_master.h"
@@ -24,6 +24,12 @@
 #include "driver/uart.h"
 #endif
 
+#if CONFIG_EPPP_LINK_DEVICE_ETH
+#define EPPP_NEEDS_TASK 0
+#else
+#define EPPP_NEEDS_TASK 1
+#endif
+
 static const int GOT_IPV4 = BIT0;
 static const int CONNECTION_FAILED = BIT1;
 #define CONNECT_BITS (GOT_IPV4|CONNECTION_FAILED)
@@ -98,6 +104,8 @@ esp_err_t eppp_sdio_host_init(struct eppp_config_sdio_s *config);
 esp_err_t eppp_sdio_slave_init(void);
 void eppp_sdio_slave_deinit(void);
 void eppp_sdio_host_deinit(void);
+#elif CONFIG_EPPP_LINK_DEVICE_ETH
+
 #else
 static esp_err_t transmit(void *h, void *buffer, size_t len)
 {
@@ -224,6 +232,8 @@ static esp_netif_t *netif_init(eppp_type_t role, eppp_config_t *eppp_config)
         .handle = h,
 #if CONFIG_EPPP_LINK_DEVICE_SDIO
         .transmit = role == EPPP_CLIENT ? eppp_sdio_host_tx : eppp_sdio_slave_tx,
+#elif CONFIG_EPPP_LINK_DEVICE_ETH
+        .transmit = eppp_transport_tx,
 #else
         .transmit = transmit,
 #endif
@@ -691,6 +701,7 @@ esp_err_t eppp_perform(esp_netif_t *netif)
 
 #endif // CONFIG_EPPP_LINK_DEVICE_SPI / UART
 
+#if EPPP_NEEDS_TASK
 static void ppp_task(void *args)
 {
     esp_netif_t *netif = args;
@@ -699,6 +710,7 @@ static void ppp_task(void *args)
     h->exited = true;
     vTaskDelete(NULL);
 }
+#endif
 
 static bool have_some_eppp_netif(esp_netif_t *netif, void *ctx)
 {
@@ -738,6 +750,8 @@ void eppp_deinit(esp_netif_t *netif)
     } else {
         eppp_sdio_slave_deinit();
     }
+#elif CONFIG_EPPP_LINK_DEVICE_ETH
+    eppp_transport_deinit();
 #endif
     netif_deinit(netif);
 }
@@ -781,6 +795,13 @@ esp_netif_t *eppp_init(eppp_type_t role, eppp_config_t *config)
         ESP_LOGE(TAG, "Failed to initialize SDIO %d", ret);
         return NULL;
     }
+#elif CONFIG_EPPP_LINK_DEVICE_ETH
+    esp_err_t ret = eppp_transport_init(config, netif);
+    if (ret != ESP_OK) {
+        ESP_LOGE(TAG, "Failed to initialize SDIO %d", ret);
+        return NULL;
+    }
+
 #endif
     return netif;
 }
@@ -834,12 +855,13 @@ esp_netif_t *eppp_open(eppp_type_t role, eppp_config_t *config, int connect_time
     }
 
     eppp_netif_start(netif);
-
+#if EPPP_NEEDS_TASK
     if (xTaskCreate(ppp_task, "ppp connect", config->task.stack_size, netif, config->task.priority, NULL) != pdTRUE) {
         ESP_LOGE(TAG, "Failed to create a ppp connection task");
         eppp_deinit(netif);
         return NULL;
     }
+#endif
     int netif_cnt = get_netif_num(netif);
     if (netif_cnt < 0) {
         eppp_close(netif);

components/eppp_link/eppp_transport.h

@@ -0,0 +1,14 @@
+/*
+ * SPDX-FileCopyrightText: 2024 Espressif Systems (Shanghai) CO LTD
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#pragma once
+
+esp_err_t eppp_transport_init(eppp_config_t *config, esp_netif_t *esp_netif);
+
+esp_err_t eppp_transport_tx(void *h, void *buffer, size_t len);
+
+esp_err_t eppp_transport_rx(esp_netif_t *netif);
+
+void eppp_transport_deinit(void);

components/eppp_link/examples/host/sdkconfig.ci.eth

@@ -0,0 +1,2 @@
+CONFIG_IDF_TARGET="esp32"
+CONFIG_EPPP_LINK_DEVICE_ETH=y

components/eppp_link/examples/host/sdkconfig.ci.sdio

@@ -0,0 +1,2 @@
+CONFIG_IDF_TARGET="esp32p4"
+CONFIG_EPPP_LINK_DEVICE_SDIO=y

components/eppp_link/examples/slave/sdkconfig.ci.eth

@@ -0,0 +1,2 @@
+CONFIG_IDF_TARGET="esp32"
+CONFIG_EPPP_LINK_DEVICE_ETH=y

components/eppp_link/examples/slave/sdkconfig.ci.sdio

@@ -0,0 +1,2 @@
+CONFIG_IDF_TARGET="esp32c6"
+CONFIG_EPPP_LINK_DEVICE_SDIO=y

components/eppp_link/idf_component.yml

@@ -4,3 +4,4 @@ description: The component provides a general purpose PPP connectivity, typicall
 dependencies:
   idf: '>=5.2'
   espressif/esp_serial_slave_link: "^1.1.0"
+  espressif/ethernet_init: '>=0.0.7'

components/eppp_link/include/eppp_link.h

@@ -63,6 +63,7 @@ typedef enum eppp_transport {
     EPPP_TRANSPORT_UART,
     EPPP_TRANSPORT_SPI,
     EPPP_TRANSPORT_SDIO,
+    EPPP_TRANSPORT_ETHERNET,
 } eppp_transport_t;