Step 1: Ethernet up (IP101/RMII), DHCP, link and IP logged

- aes67_board: Waveshare ESP32-P4-ETH pin profile and EMAC + IP101 driver
  install (PHY addr 1, reset GPIO51, ref clock in on GPIO50).
- aes67_net: Ethernet netif with DHCP client; logs link up/down (speed,
  duplex, MAC) and the DHCP lease.
- Verified on board: 100 Mbps full duplex, DHCP lease in ~8 s, ping
  0% loss, ~0.2 ms RTT.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

components/aes67_net/CMakeLists.txt

@@ -1,2 +1,3 @@
 idf_component_register(SRCS "aes67_net.c"
-                       INCLUDE_DIRS "include")
+                       INCLUDE_DIRS "include"
+                       REQUIRES esp_eth esp_netif esp_event)

components/aes67_net/aes67_net.c

@@ -1,7 +1,58 @@
 #include "aes67_net.h"
 
-// Stub (build step 0).
-esp_err_t aes67_net_init(void)
+#include "esp_eth.h"
+#include "esp_event.h"
+#include "esp_log.h"
+#include "esp_netif.h"
+
+static const char *TAG = "net";
+
+static void eth_event(void *arg, esp_event_base_t base, int32_t id, void *data)
 {
-    return ESP_OK;
+    esp_eth_handle_t eth = *(esp_eth_handle_t *)data;
+
+    switch (id) {
+    case ETHERNET_EVENT_CONNECTED: {
+        uint8_t mac[6];
+        eth_speed_t speed;
+        eth_duplex_t duplex;
+        esp_eth_ioctl(eth, ETH_CMD_G_MAC_ADDR, mac);
+        esp_eth_ioctl(eth, ETH_CMD_G_SPEED, &speed);
+        esp_eth_ioctl(eth, ETH_CMD_G_DUPLEX_MODE, &duplex);
+        ESP_LOGI(TAG, "link up: %s Mbps %s duplex, MAC %02x:%02x:%02x:%02x:%02x:%02x",
+                 speed == ETH_SPEED_100M ? "100" : "10", duplex == ETH_DUPLEX_FULL ? "full" : "half",
+                 mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
+        break;
+    }
+    case ETHERNET_EVENT_DISCONNECTED:
+        ESP_LOGW(TAG, "link down");
+        break;
+    default:
+        break;
+    }
+}
+
+static void ip_event(void *arg, esp_event_base_t base, int32_t id, void *data)
+{
+    const ip_event_got_ip_t *ev = data;
+    ESP_LOGI(TAG, "got IP " IPSTR " mask " IPSTR " gw " IPSTR,
+             IP2STR(&ev->ip_info.ip), IP2STR(&ev->ip_info.netmask), IP2STR(&ev->ip_info.gw));
+}
+
+esp_err_t aes67_net_init(esp_eth_handle_t eth)
+{
+    ESP_ERROR_CHECK(esp_netif_init());
+    esp_err_t err = esp_event_loop_create_default();
+    if (err != ESP_OK && err != ESP_ERR_INVALID_STATE) {
+        return err;
+    }
+
+    esp_netif_config_t netif_cfg = ESP_NETIF_DEFAULT_ETH();
+    esp_netif_t *netif = esp_netif_new(&netif_cfg);
+    ESP_ERROR_CHECK(esp_netif_attach(netif, esp_eth_new_netif_glue(eth)));
+
+    ESP_ERROR_CHECK(esp_event_handler_register(ETH_EVENT, ESP_EVENT_ANY_ID, eth_event, NULL));
+    ESP_ERROR_CHECK(esp_event_handler_register(IP_EVENT, IP_EVENT_ETH_GOT_IP, ip_event, NULL));
+
+    return esp_eth_start(eth);
 }

components/aes67_net/include/aes67_net.h

@@ -3,5 +3,7 @@
 #pragma once
 
 #include "esp_err.h"
+#include "esp_eth_driver.h"
 
-esp_err_t aes67_net_init(void);
+// Attach a netif (DHCP client) to the Ethernet driver and start it. Logs link and IP events.
+esp_err_t aes67_net_init(esp_eth_handle_t eth);