esp32: Implement wired Ethernet via network.LAN().

Updates to Makefile, modnetwork.c, and addition of network_lan.c to
implement `network.LAN()` object for wired PHY objects.
diff --git a/ports/esp32/network_lan.c b/ports/esp32/network_lan.c
new file mode 100644
index 0000000..fba4de7
--- /dev/null
+++ b/ports/esp32/network_lan.c
@@ -0,0 +1,203 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 "Eric Poulsen" <eric@zyxod.com>
+ *
+ * Based on the ESP IDF example code which is Public Domain / CC0
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/runtime.h"
+#include "py/mphal.h"
+
+#include "eth_phy/phy.h"
+#include "eth_phy/phy_tlk110.h"
+#include "eth_phy/phy_lan8720.h"
+#include "tcpip_adapter.h"
+
+#include "modnetwork.h"
+
+typedef struct _lan_if_obj_t {
+    mp_obj_base_t base;
+    int if_id; // MUST BE FIRST to match wlan_if_obj_t
+    bool initialized;
+    bool active;
+    uint8_t mdc_pin;
+    uint8_t mdio_pin;
+    int8_t phy_power_pin;
+    uint8_t phy_addr;
+    uint8_t phy_type;
+    eth_phy_check_link_func link_func;
+    eth_phy_power_enable_func power_func;
+} lan_if_obj_t;
+
+const mp_obj_type_t lan_if_type;
+STATIC lan_if_obj_t lan_obj = {{&lan_if_type}, ESP_IF_ETH, false, false};
+
+STATIC void phy_power_enable(bool enable) {
+    lan_if_obj_t* self = &lan_obj;
+
+    if (self->phy_power_pin != -1) {
+
+        if (!enable) {
+            // Do the PHY-specific power_enable(false) function before powering down
+            self->power_func(false);
+        }
+
+        gpio_pad_select_gpio(self->phy_power_pin);
+        gpio_set_direction(self->phy_power_pin, GPIO_MODE_OUTPUT);
+        if (enable) {
+            gpio_set_level(self->phy_power_pin, 1);
+        } else {
+            gpio_set_level(self->phy_power_pin, 0);
+        }
+
+        // Allow the power up/down to take effect, min 300us
+        vTaskDelay(1);
+
+        if (enable) {
+            // Run the PHY-specific power on operations now the PHY has power
+            self->power_func(true);
+        }
+    }
+}
+
+STATIC void init_lan_rmii() {
+    lan_if_obj_t* self = &lan_obj;
+    phy_rmii_configure_data_interface_pins();
+    phy_rmii_smi_configure_pins(self->mdc_pin, self->mdio_pin);
+}
+
+STATIC mp_obj_t get_lan(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    lan_if_obj_t* self = &lan_obj;
+
+    if (self->initialized) {
+        return MP_OBJ_FROM_PTR(&lan_obj);
+    }
+
+    enum { ARG_id, ARG_mdc, ARG_mdio, ARG_power, ARG_phy_addr, ARG_phy_type };
+    static const mp_arg_t allowed_args[] = {
+        { MP_QSTR_id,           MP_ARG_OBJ, {.u_obj = mp_const_none} },
+        { MP_QSTR_mdc,          MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_OBJ },
+        { MP_QSTR_mdio,         MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_OBJ },
+        { MP_QSTR_power,        MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_OBJ },
+        { MP_QSTR_phy_addr,     MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_INT },
+        { MP_QSTR_phy_type,     MP_ARG_KW_ONLY | MP_ARG_REQUIRED | MP_ARG_INT },
+    };
+
+    mp_arg_val_t args[MP_ARRAY_SIZE(allowed_args)];
+    mp_arg_parse_all(n_args, pos_args, kw_args, MP_ARRAY_SIZE(allowed_args), allowed_args, args);
+
+    if (args[ARG_id].u_obj != mp_const_none) {
+        if (mp_obj_get_int(args[ARG_id].u_obj) != 0) {
+            mp_raise_ValueError("invalid LAN interface identifier");
+        }
+    }
+
+    self->mdc_pin = machine_pin_get_id(args[ARG_mdc].u_obj);
+    self->mdio_pin = machine_pin_get_id(args[ARG_mdio].u_obj);
+    self->phy_power_pin = args[ARG_power].u_obj == mp_const_none ? -1 : machine_pin_get_id(args[ARG_power].u_obj);
+
+    if (args[ARG_phy_addr].u_int < 0x00 || args[ARG_phy_addr].u_int > 0x1f) {
+        mp_raise_ValueError("invalid phy address");
+    }
+
+    if (args[ARG_phy_type].u_int != PHY_LAN8720 && args[ARG_phy_type].u_int != PHY_TLK110) {
+        mp_raise_ValueError("invalid phy type");
+    }
+
+    eth_config_t config;
+
+    switch (args[ARG_phy_type].u_int) {
+        case PHY_TLK110:
+            config = phy_tlk110_default_ethernet_config;
+            break;
+        case PHY_LAN8720:
+            config = phy_lan8720_default_ethernet_config;
+            break;
+    }
+
+    self->link_func = config.phy_check_link;
+
+    // Replace default power func with our own
+    self->power_func = config.phy_power_enable;
+    config.phy_power_enable = phy_power_enable;
+
+    config.phy_addr = args[ARG_phy_addr].u_int;
+    config.gpio_config = init_lan_rmii;
+    config.tcpip_input = tcpip_adapter_eth_input;
+
+    if (esp_eth_init(&config) == ESP_OK) {
+        self->active = false;
+        self->initialized = true;
+    } else {
+        mp_raise_msg(&mp_type_OSError, "esp_eth_init() failed");
+    }
+    return MP_OBJ_FROM_PTR(&lan_obj);
+}
+MP_DEFINE_CONST_FUN_OBJ_KW(get_lan_obj, 0, get_lan);
+
+STATIC mp_obj_t lan_active(size_t n_args, const mp_obj_t *args) {
+    lan_if_obj_t *self = MP_OBJ_TO_PTR(args[0]);
+
+    if (n_args > 1) {
+        if (mp_obj_is_true(args[1])) {
+            self->active = (esp_eth_enable() == ESP_OK);
+            if (!self->active) {
+                mp_raise_msg(&mp_type_OSError, "ethernet enable failed");
+            }
+        } else {
+            self->active = !(esp_eth_disable() == ESP_OK);
+            if (self->active) {
+                mp_raise_msg(&mp_type_OSError, "ethernet disable failed");
+            }
+        }
+    }
+    return mp_obj_new_bool(self->active);
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(lan_active_obj, 1, 2, lan_active);
+
+STATIC mp_obj_t lan_status(mp_obj_t self_in) {
+    return mp_const_none;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(lan_status_obj, lan_status);
+
+STATIC mp_obj_t lan_isconnected(mp_obj_t self_in) {
+    lan_if_obj_t *self = MP_OBJ_TO_PTR(self_in);
+    return self->active ? mp_obj_new_bool(self->link_func()) : mp_const_false;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(lan_isconnected_obj, lan_isconnected);
+
+STATIC const mp_rom_map_elem_t lan_if_locals_dict_table[] = {
+    { MP_ROM_QSTR(MP_QSTR_active), MP_ROM_PTR(&lan_active_obj) },
+    { MP_ROM_QSTR(MP_QSTR_isconnected), MP_ROM_PTR(&lan_isconnected_obj) },
+    { MP_ROM_QSTR(MP_QSTR_status), MP_ROM_PTR(&lan_status_obj) },
+    { MP_ROM_QSTR(MP_QSTR_ifconfig), MP_ROM_PTR(&esp_ifconfig_obj) },
+};
+
+STATIC MP_DEFINE_CONST_DICT(lan_if_locals_dict, lan_if_locals_dict_table);
+
+const mp_obj_type_t lan_if_type = {
+    { &mp_type_type },
+    .name = MP_QSTR_LAN,
+    .locals_dict = (mp_obj_dict_t*)&lan_if_locals_dict,
+};