ethernet: support flow control for esp32 emac

components/esp_eth/include/esp_eth_phy.h

@@ -160,6 +160,19 @@ struct esp_eth_phy_s {
     */
     esp_err_t (*get_addr)(esp_eth_phy_t *phy, uint32_t *addr);
 
+    /**
+    * @brief Advertise pause function supported by MAC layer
+    *
+    * @param[in] phy: Ethernet PHY instance
+    * @param[out] addr: Pause ability
+    *
+    * @return
+    *      - ESP_OK: Advertise pause ability successfully
+    *      - ESP_ERR_INVALID_ARG: Advertise pause ability failed because of invalid argument
+    *
+    */
+    esp_err_t (*advertise_pause_ability)(esp_eth_phy_t *phy, uint32_t ability);
+
     /**
     * @brief Free memory of Ethernet PHY instance
     *