feat(esp_eth): added new generic PHY driver

examples/ethernet/basic/components/ethernet_init/Kconfig.projbuild

@@ -17,6 +17,15 @@ menu "Example Ethernet Configuration"
             help
                 Select the Ethernet PHY device to use in the example.
 
+            config EXAMPLE_ETH_PHY_GENERIC
+                bool "Generic 802.3 PHY"
+                help
+                    Any Ethernet PHY chip compliant with IEEE 802.3 can be used. However, while
+                    basic functionality should always work, some specific features might be limited,
+                    even if the PHY meets IEEE 802.3 standard. A typical example is loopback
+                    functionality, where certain PHYs may require setting a specific speed mode to
+                    operate correctly.
+
             config EXAMPLE_ETH_PHY_IP101
                 bool "IP101"
                 help

examples/ethernet/basic/components/ethernet_init/ethernet_init.c

@@ -83,7 +83,9 @@ static esp_eth_handle_t eth_init_internal(esp_eth_mac_t **mac_out, esp_eth_phy_t
     // Create new ESP32 Ethernet MAC instance
     esp_eth_mac_t *mac = esp_eth_mac_new_esp32(&esp32_emac_config, &mac_config);
     // Create new PHY instance based on board configuration
-#if CONFIG_EXAMPLE_ETH_PHY_IP101
+#if CONFIG_EXAMPLE_ETH_PHY_GENERIC
+    esp_eth_phy_t *phy = esp_eth_phy_new_generic(&phy_config);
+#elif CONFIG_EXAMPLE_ETH_PHY_IP101
     esp_eth_phy_t *phy = esp_eth_phy_new_ip101(&phy_config);
 #elif CONFIG_EXAMPLE_ETH_PHY_RTL8201
     esp_eth_phy_t *phy = esp_eth_phy_new_rtl8201(&phy_config);

examples/ethernet/basic/pytest_eth_basic.py

@@ -10,6 +10,7 @@ from pytest_embedded import Dut
 @pytest.mark.esp32
 @pytest.mark.parametrize('config', [
     pytest.param('default_ip101', marks=[pytest.mark.ethernet_router]),
+    pytest.param('default_generic', marks=[pytest.mark.ethernet_router]),
     pytest.param('default_dm9051', marks=[pytest.mark.eth_dm9051]),
 ], indirect=True)
 def test_esp_eth_basic(

examples/ethernet/basic/sdkconfig.ci.default_generic

@@ -0,0 +1,11 @@
+CONFIG_EXAMPLE_USE_INTERNAL_ETHERNET=y
+CONFIG_EXAMPLE_ETH_PHY_GENERIC=y
+CONFIG_EXAMPLE_ETH_MDC_GPIO=23
+CONFIG_EXAMPLE_ETH_MDIO_GPIO=18
+CONFIG_EXAMPLE_ETH_PHY_RST_GPIO=5
+CONFIG_EXAMPLE_ETH_PHY_ADDR=1
+
+CONFIG_ETH_ENABLED=y
+CONFIG_ETH_USE_ESP32_EMAC=y
+CONFIG_ETH_PHY_INTERFACE_RMII=y
+CONFIG_ETH_RMII_CLK_INPUT=y