1/**
2 * @file
3 * Ethernet Interface Skeleton
4 *
5 */
6
7/*
8 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
9 * All rights reserved.
10 *
11 * Redistribution and use in source and binary forms, with or without modification,
12 * are permitted provided that the following conditions are met:
13 *
14 * 1. Redistributions of source code must retain the above copyright notice,
15 *    this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright notice,
17 *    this list of conditions and the following disclaimer in the documentation
18 *    and/or other materials provided with the distribution.
19 * 3. The name of the author may not be used to endorse or promote products
20 *    derived from this software without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
23 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
24 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
25 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
26 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
27 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
29 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
30 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
31 * OF SUCH DAMAGE.
32 *
33 * This file is part of the lwIP TCP/IP stack.
34 *
35 * Author: Adam Dunkels <adam@sics.se>
36 *
37 */
38
39/*
40 * This file is a skeleton for developing Ethernet network interface
41 * drivers for lwIP. Add code to the low_level functions and do a
42 * search-and-replace for the word "ethernetif" to replace it with
43 * something that better describes your network interface.
44 */
45
46#include "lwip/opt.h"
47
48#if 0                           /* don't build, this is only a skeleton, see previous comment */
49
50#include "lwip/def.h"
51#include "lwip/mem.h"
52#include "lwip/pbuf.h"
53#include "lwip/sys.h"
54#include <lwip/stats.h>
55#include <lwip/snmp.h>
56#include "netif/etharp.h"
57#include "netif/ppp_oe.h"
58
59/* Define those to better describe your network interface. */
60#define IFNAME0 'e'
61#define IFNAME1 'n'
62
63/**
64 * Helper struct to hold private data used to operate your ethernet interface.
65 * Keeping the ethernet address of the MAC in this struct is not necessary
66 * as it is already kept in the struct netif.
67 * But this is only an example, anyway...
68 */
69struct ethernetif {
70    struct eth_addr *ethaddr;
71    /* Add whatever per-interface state that is needed here. */
72};
73
74/* Forward declarations. */
75static void ethernetif_input(struct netif *netif);
76
77/**
78 * In this function, the hardware should be initialized.
79 * Called from ethernetif_init().
80 *
81 * @param netif the already initialized lwip network interface structure
82 *        for this ethernetif
83 */
84static void low_level_init(struct netif *netif)
85{
86    struct ethernetif *ethernetif = netif->state;
87
88    /* set MAC hardware address length */
89    netif->hwaddr_len = ETHARP_HWADDR_LEN;
90
91    /* set MAC hardware address */
92    netif->hwaddr[0] =;
93    ... netif->hwaddr[5] =;
94
95    /* maximum transfer unit */
96    netif->mtu = 1500;
97
98    /* device capabilities */
99    /* don't set NETIF_FLAG_ETHARP if this device is not an ethernet one */
100    netif->flags =
101      NETIF_FLAG_BROADCAST | NETIF_FLAG_ETHARP | NETIF_FLAG_LINK_UP;
102
103    /* Do whatever else is needed to initialize interface. */
104}
105
106/**
107 * This function should do the actual transmission of the packet. The packet is
108 * contained in the pbuf that is passed to the function. This pbuf
109 * might be chained.
110 *
111 * @param netif the lwip network interface structure for this ethernetif
112 * @param p the MAC packet to send (e.g. IP packet including MAC addresses and type)
113 * @return ERR_OK if the packet could be sent
114 *         an err_t value if the packet couldn't be sent
115 *
116 * @note Returning ERR_MEM here if a DMA queue of your MAC is full can lead to
117 *       strange results. You might consider waiting for space in the DMA queue
118 *       to become availale since the stack doesn't retry to send a packet
119 *       dropped because of memory failure (except for the TCP timers).
120 */
121
122static err_t low_level_output(struct netif *netif, struct pbuf *p)
123{
124    struct ethernetif *ethernetif = netif->state;
125    struct pbuf *q;
126
127    initiate transfer();
128
129#if ETH_PAD_SIZE
130    pbuf_header(p, -ETH_PAD_SIZE);      /* drop the padding word */
131#endif
132
133    for (q = p; q != NULL; q = q->next) {
134        /* Send the data from the pbuf to the interface, one pbuf at a
135           time. The size of the data in each pbuf is kept in the ->len
136           variable. */
137        send data from(q->payload, q->len);
138    }
139
140    signal that packet should be sent();
141
142#if ETH_PAD_SIZE
143    pbuf_header(p, ETH_PAD_SIZE);       /* reclaim the padding word */
144#endif
145
146    LINK_STATS_INC(link.xmit);
147
148    return ERR_OK;
149}
150
151/**
152 * Should allocate a pbuf and transfer the bytes of the incoming
153 * packet from the interface into the pbuf.
154 *
155 * @param netif the lwip network interface structure for this ethernetif
156 * @return a pbuf filled with the received packet (including MAC header)
157 *         NULL on memory error
158 */
159static struct pbuf *low_level_input(struct netif *netif)
160{
161    struct ethernetif *ethernetif = netif->state;
162    struct pbuf *p, *q;
163    u16_t len;
164
165    /* Obtain the size of the packet and put it into the "len"
166       variable. */
167    len =;
168
169#if ETH_PAD_SIZE
170    len += ETH_PAD_SIZE;        /* allow room for Ethernet padding */
171#endif
172
173    /* We allocate a pbuf chain of pbufs from the pool. */
174    p = pbuf_alloc(PBUF_RAW, len, PBUF_POOL);
175
176    if (p != NULL) {
177
178#if ETH_PAD_SIZE
179        pbuf_header(p, -ETH_PAD_SIZE);  /* drop the padding word */
180#endif
181
182        /* We iterate over the pbuf chain until we have read the entire
183         * packet into the pbuf. */
184        for (q = p; q != NULL; q = q->next) {
185            /* Read enough bytes to fill this pbuf in the chain. The
186             * available data in the pbuf is given by the q->len
187             * variable. */
188            read data into(q->payload, q->len);
189        }
190        acknowledge that packet has been read();
191
192#if ETH_PAD_SIZE
193        pbuf_header(p, ETH_PAD_SIZE);   /* reclaim the padding word */
194#endif
195
196        LINK_STATS_INC(link.recv);
197    } else {
198        drop packet();
199
200        LINK_STATS_INC(link.memerr);
201        LINK_STATS_INC(link.drop);
202    }
203
204    return p;
205}
206
207/**
208 * This function should be called when a packet is ready to be read
209 * from the interface. It uses the function low_level_input() that
210 * should handle the actual reception of bytes from the network
211 * interface. Then the type of the received packet is determined and
212 * the appropriate input function is called.
213 *
214 * @param netif the lwip network interface structure for this ethernetif
215 */
216static void ethernetif_input(struct netif *netif)
217{
218    struct ethernetif *ethernetif;
219    struct eth_hdr *ethhdr;
220    struct pbuf *p;
221
222    ethernetif = netif->state;
223
224    /* move received packet into a new pbuf */
225    p = low_level_input(netif);
226    /* no packet could be read, silently ignore this */
227    if (p == NULL)
228        return;
229    /* points to packet payload, which starts with an Ethernet header */
230    ethhdr = p->payload;
231
232    switch (htons(ethhdr->type)) {
233            /* IP or ARP packet? */
234        case ETHTYPE_IP:
235        case ETHTYPE_ARP:
236#if PPPOE_SUPPORT
237            /* PPPoE packet? */
238        case ETHTYPE_PPPOEDISC:
239        case ETHTYPE_PPPOE:
240#endif                          /* PPPOE_SUPPORT */
241            /* full packet send to tcpip_thread to process */
242            if (netif->input(p, netif) != ERR_OK) {
243                LWIP_DEBUGF(NETIF_DEBUG,
244                            ("ethernetif_input: IP input error\n"));
245                pbuf_free(p);
246                p = NULL;
247            }
248            break;
249
250        default:
251            pbuf_free(p);
252            p = NULL;
253            break;
254    }
255}
256
257/**
258 * Should be called at the beginning of the program to set up the
259 * network interface. It calls the function low_level_init() to do the
260 * actual setup of the hardware.
261 *
262 * This function should be passed as a parameter to netif_add().
263 *
264 * @param netif the lwip network interface structure for this ethernetif
265 * @return ERR_OK if the loopif is initialized
266 *         ERR_MEM if private data couldn't be allocated
267 *         any other err_t on error
268 */
269err_t ethernetif_init(struct netif *netif)
270{
271    struct ethernetif *ethernetif;
272
273    LWIP_ASSERT("netif != NULL", (netif != NULL));
274
275    ethernetif = mem_malloc(sizeof(struct ethernetif));
276    if (ethernetif == NULL) {
277        LWIP_DEBUGF(NETIF_DEBUG, ("ethernetif_init: out of memory\n"));
278        return ERR_MEM;
279    }
280#if LWIP_NETIF_HOSTNAME
281    /* Initialize interface hostname */
282    netif->hostname = "lwip";
283#endif                          /* LWIP_NETIF_HOSTNAME */
284
285    /*
286     * Initialize the snmp variables and counters inside the struct netif.
287     * The last argument should be replaced with your link speed, in units
288     * of bits per second.
289     */
290    NETIF_INIT_SNMP(netif, snmp_ifType_ethernet_csmacd,
291                    LINK_SPEED_OF_YOUR_NETIF_IN_BPS);
292
293    netif->state = ethernetif;
294    netif->name[0] = IFNAME0;
295    netif->name[1] = IFNAME1;
296    /* We directly use etharp_output() here to save a function call.
297     * You can instead declare your own function an call etharp_output()
298     * from it if you have to do some checks before sending (e.g. if link
299     * is available...) */
300    netif->output = etharp_output;
301    netif->linkoutput = low_level_output;
302
303    ethernetif->ethaddr = (struct eth_addr *) &(netif->hwaddr[0]);
304
305    /* initialize the hardware */
306    low_level_init(netif);
307
308    return ERR_OK;
309}
310
311#endif                          /* 0 */
312