ethernetif.c

00001 /**
00002  * @file
00003  * Ethernet Interface Skeleton
00004  *
00005  */
00006 
00007 /*
00008  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
00009  * All rights reserved. 
00010  * 
00011  * Redistribution and use in source and binary forms, with or without modification, 
00012  * are permitted provided that the following conditions are met:
00013  *
00014  * 1. Redistributions of source code must retain the above copyright notice,
00015  *    this list of conditions and the following disclaimer.
00016  * 2. Redistributions in binary form must reproduce the above copyright notice,
00017  *    this list of conditions and the following disclaimer in the documentation
00018  *    and/or other materials provided with the distribution.
00019  * 3. The name of the author may not be used to endorse or promote products
00020  *    derived from this software without specific prior written permission. 
00021  *
00022  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
00023  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
00024  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
00025  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
00026  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
00027  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
00028  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
00029  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
00030  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
00031  * OF SUCH DAMAGE.
00032  *
00033  * This file is part of the lwIP TCP/IP stack.
00034  * 
00035  * Author: Adam Dunkels <adam@sics.se>
00036  *
00037  */
00038 
00039 /*
00040  * This file is a skeleton for developing Ethernet network interface
00041  * drivers for lwIP. Add code to the low_level functions and do a
00042  * search-and-replace for the word "ethernetif" to replace it with
00043  * something that better describes your network interface.
00044  */
00045 
00046 #include "lwip/opt.h"
00047 
00048 #if 0 /* don't build, this is only a skeleton, see previous comment */
00049 
00050 #include "lwip/def.h"
00051 #include "lwip/mem.h"
00052 #include "lwip/pbuf.h"
00053 #include "lwip/sys.h"
00054 #include <lwip/stats.h>
00055 #include <lwip/snmp.h>
00056 #include "netif/etharp.h"
00057 #include "netif/ppp_oe.h"
00058 
00059 /* Define those to better describe your network interface. */
00060 #define IFNAME0 'e'
00061 #define IFNAME1 'n'
00062 
00063 /**
00064  * Helper struct to hold private data used to operate your ethernet interface.
00065  * Keeping the ethernet address of the MAC in this struct is not necessary
00066  * as it is already kept in the struct netif.
00067  * But this is only an example, anyway...
00068  */
00069 struct ethernetif {
00070   struct eth_addr *ethaddr;
00071   /* Add whatever per-interface state that is needed here. */
00072 };
00073 
00074 /* Forward declarations. */
00075 static void  ethernetif_input(struct netif *netif);
00076 
00077 /**
00078  * In this function, the hardware should be initialized.
00079  * Called from ethernetif_init().
00080  *
00081  * @param netif the already initialized lwip network interface structure
00082  *        for this ethernetif
00083  */
00084 static void
00085 low_level_init(struct netif *netif)
00086 {
00087   struct ethernetif *ethernetif = netif->state;
00088   
00089   /* set MAC hardware address length */
00090   netif->hwaddr_len = ETHARP_HWADDR_LEN;
00091 
00092   /* set MAC hardware address */
00093   netif->hwaddr[0] = 8C;
00094   netif->hwaddr[1] = 70;
00095   netif->hwaddr[2] = 5a;
00096   netif->hwaddr[3] = d4;
00097   netif->hwaddr[4] = 96;
00098   ...
00099   netif->hwaddr[5] = c4;
00100 
00101   /* maximum transfer unit */
00102   netif->mtu = 1500;
00103   
00104   /* device capabilities */
00105   /* don't set NETIF_FLAG_ETHARP if this device is not an ethernet one */
00106   netif->flags = NETIF_FLAG_BROADCAST | NETIF_FLAG_ETHARP | NETIF_FLAG_LINK_UP;
00107  
00108   /* Do whatever else is needed to initialize interface. */  
00109 }
00110 
00111 /**
00112  * This function should do the actual transmission of the packet. The packet is
00113  * contained in the pbuf that is passed to the function. This pbuf
00114  * might be chained.
00115  *
00116  * @param netif the lwip network interface structure for this ethernetif
00117  * @param p the MAC packet to send (e.g. IP packet including MAC addresses and type)
00118  * @return ERR_OK if the packet could be sent
00119  *         an err_t value if the packet couldn't be sent
00120  *
00121  * @note Returning ERR_MEM here if a DMA queue of your MAC is full can lead to
00122  *       strange results. You might consider waiting for space in the DMA queue
00123  *       to become availale since the stack doesn't retry to send a packet
00124  *       dropped because of memory failure (except for the TCP timers).
00125  */
00126 
00127 static err_t
00128 low_level_output(struct netif *netif, struct pbuf *p)
00129 {
00130   struct ethernetif *ethernetif = netif->state;
00131   struct pbuf *q;
00132 
00133   initiate transfer();
00134   
00135 #if ETH_PAD_SIZE
00136   pbuf_header(p, -ETH_PAD_SIZE); /* drop the padding word */
00137 #endif
00138 
00139   for(q = p; q != NULL; q = q->next) {
00140     /* Send the data from the pbuf to the interface, one pbuf at a
00141        time. The size of the data in each pbuf is kept in the ->len
00142        variable. */
00143     send data from(q->payload, q->len);
00144   }
00145 
00146   signal that packet should be sent();
00147 
00148 #if ETH_PAD_SIZE
00149   pbuf_header(p, ETH_PAD_SIZE); /* reclaim the padding word */
00150 #endif
00151   
00152   LINK_STATS_INC(link.xmit);
00153 
00154   return ERR_OK;
00155 }
00156 
00157 /**
00158  * Should allocate a pbuf and transfer the bytes of the incoming
00159  * packet from the interface into the pbuf.
00160  *
00161  * @param netif the lwip network interface structure for this ethernetif
00162  * @return a pbuf filled with the received packet (including MAC header)
00163  *         NULL on memory error
00164  */
00165 static struct pbuf *
00166 low_level_input(struct netif *netif)
00167 {
00168   struct ethernetif *ethernetif = netif->state;
00169   struct pbuf *p, *q;
00170   u16_t len;
00171 
00172   /* Obtain the size of the packet and put it into the "len"
00173      variable. */
00174   len = ;
00175 
00176 #if ETH_PAD_SIZE
00177   len += ETH_PAD_SIZE; /* allow room for Ethernet padding */
00178 #endif
00179 
00180   /* We allocate a pbuf chain of pbufs from the pool. */
00181   p = pbuf_alloc(PBUF_RAW, len, PBUF_POOL);
00182   
00183   if (p != NULL) {
00184 
00185 #if ETH_PAD_SIZE
00186     pbuf_header(p, -ETH_PAD_SIZE); /* drop the padding word */
00187 #endif
00188 
00189     /* We iterate over the pbuf chain until we have read the entire
00190      * packet into the pbuf. */
00191     for(q = p; q != NULL; q = q->next) {
00192       /* Read enough bytes to fill this pbuf in the chain. The
00193        * available data in the pbuf is given by the q->len
00194        * variable.
00195        * This does not necessarily have to be a memcpy, you can also preallocate
00196        * pbufs for a DMA-enabled MAC and after receiving truncate it to the
00197        * actually received size. In this case, ensure the tot_len member of the
00198        * pbuf is the sum of the chained pbuf len members.
00199        */
00200       read data into(q->payload, q->len);
00201     }
00202     acknowledge that packet has been read();
00203 
00204 #if ETH_PAD_SIZE
00205     pbuf_header(p, ETH_PAD_SIZE); /* reclaim the padding word */
00206 #endif
00207 
00208     LINK_STATS_INC(link.recv);
00209   } else {
00210     drop packet();
00211     LINK_STATS_INC(link.memerr);
00212     LINK_STATS_INC(link.drop);
00213   }
00214 
00215   return p;  
00216 }
00217 
00218 /**
00219  * This function should be called when a packet is ready to be read
00220  * from the interface. It uses the function low_level_input() that
00221  * should handle the actual reception of bytes from the network
00222  * interface. Then the type of the received packet is determined and
00223  * the appropriate input function is called.
00224  *
00225  * @param netif the lwip network interface structure for this ethernetif
00226  */
00227 static void
00228 ethernetif_input(struct netif *netif)
00229 {
00230   struct ethernetif *ethernetif;
00231   struct eth_hdr *ethhdr;
00232   struct pbuf *p;
00233 
00234   ethernetif = netif->state;
00235 
00236   /* move received packet into a new pbuf */
00237   p = low_level_input(netif);
00238   /* no packet could be read, silently ignore this */
00239   if (p == NULL) return;
00240   /* points to packet payload, which starts with an Ethernet header */
00241   ethhdr = p->payload;
00242 
00243   switch (htons(ethhdr->type)) {
00244   /* IP or ARP packet? */
00245   case ETHTYPE_IP:
00246   case ETHTYPE_ARP:
00247 #if PPPOE_SUPPORT
00248   /* PPPoE packet? */
00249   case ETHTYPE_PPPOEDISC:
00250   case ETHTYPE_PPPOE:
00251 #endif /* PPPOE_SUPPORT */
00252     /* full packet send to tcpip_thread to process */
00253     if (netif->input(p, netif)!=ERR_OK)
00254      { LWIP_DEBUGF(NETIF_DEBUG, ("ethernetif_input: IP input error\n"));
00255        pbuf_free(p);
00256        p = NULL;
00257      }
00258     break;
00259 
00260   default:
00261     pbuf_free(p);
00262     p = NULL;
00263     break;
00264   }
00265 }
00266 
00267 /**
00268  * Should be called at the beginning of the program to set up the
00269  * network interface. It calls the function low_level_init() to do the
00270  * actual setup of the hardware.
00271  *
00272  * This function should be passed as a parameter to netif_add().
00273  *
00274  * @param netif the lwip network interface structure for this ethernetif
00275  * @return ERR_OK if the loopif is initialized
00276  *         ERR_MEM if private data couldn't be allocated
00277  *         any other err_t on error
00278  */
00279 err_t
00280 ethernetif_init(struct netif *netif)
00281 {
00282   struct ethernetif *ethernetif;
00283 
00284   LWIP_ASSERT("netif != NULL", (netif != NULL));
00285     
00286   ethernetif = mem_malloc(sizeof(struct ethernetif));
00287   if (ethernetif == NULL) {
00288     LWIP_DEBUGF(NETIF_DEBUG, ("ethernetif_init: out of memory\n"));
00289     return ERR_MEM;
00290   }
00291 
00292 #if LWIP_NETIF_HOSTNAME
00293   /* Initialize interface hostname */
00294   netif->hostname = "lwip";
00295 #endif /* LWIP_NETIF_HOSTNAME */
00296 
00297   /*
00298    * Initialize the snmp variables and counters inside the struct netif.
00299    * The last argument should be replaced with your link speed, in units
00300    * of bits per second.
00301    */
00302   NETIF_INIT_SNMP(netif, snmp_ifType_ethernet_csmacd, LINK_SPEED_OF_YOUR_NETIF_IN_BPS);
00303 
00304   netif->state = ethernetif;
00305   netif->name[0] = IFNAME0;
00306   netif->name[1] = IFNAME1;
00307   /* We directly use etharp_output() here to save a function call.
00308    * You can instead declare your own function an call etharp_output()
00309    * from it if you have to do some checks before sending (e.g. if link
00310    * is available...) */
00311   netif->output = etharp_output;
00312   netif->linkoutput = low_level_output;
00313   
00314   ethernetif->ethaddr = (struct eth_addr *)&(netif->hwaddr[0]);
00315   
00316   /* initialize the hardware */
00317   low_level_init(netif);
00318 
00319   return ERR_OK;
00320 }
00321 
00322 #endif /* 0 */