This is a simple ethernetif.c driver to get lwIP working on the WCH CH32V208 MCU using the ch32fun lib.
It uses the chip's internal 10Mbps Ethernet MAC. The MAC address is pulled from the chip's 6-byte unique ID.

The provided main.c is an example that starts up, gets an IP address via DHCP, and runs a small HTTP server.

Usage

Initialize lwIP and add the network interface.
Poll the driver and service lwIP's timers in your main loop.

netif_add(&g_netif, &ipaddr, &netmask, &gw, NULL, &ethernetif_init, &ethernet_input);
netif_set_default(&g_netif);
netif_set_up(&g_netif);
dhcp_start(&g_netif);

while (1) {
  // poll for incoming packets
  ethernetif_input(&g_netif);

  // handle lwIP timers (for TCP, DHCP, etc.)
  sys_check_timeouts();

  // poll link for link up/down cb
  ethernetif_link_poll(&g_netif);
}

Impl note

This driver is kinda functional but not optimized

Packet RX: ~~This is done by polling~~ RXIF works now. You must call ethernetif_input() continuously in your main loop to check for and process incoming packets
Packet TX: TX isn't exactly typical DMA? The CPU has to copy the packet into a single transmit buffer and then manually start the transmission. An ISR will signal when the buffer is free to send the next packet