u-boot tftp代码分析

tftp即tftpboot,执行tftp调用do_tftpb，

int do_tftpb(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
{
    int ret;

    bootstage_mark_name(BOOTSTAGE_KERNELREAD_START, "tftp_start");
    /* 标记 record 结构体*/

    ret = netboot_common(TFTPGET, cmdtp, argc, argv);
    /* 开始tftp服务 */

    bootstage_mark_name(BOOTSTAGE_KERNELREAD_STOP, "tftp_done");
    return ret;
}


netboot_common ->
 NetLoop(TFTPGET){

...
    net_set_state(NETLOOP_CONTINUE);
    switch (net_check_prereq(protocol)) {

    ...
        case TFTPGET:
#ifdef CONFIG_CMD_TFTPPUT
        case TFTPPUT:
#endif
            /* always use ARP to get server ethernet address */
            TftpStart(protocol);//准备工作，net_set_udp_handler(TftpHandler);
            break;
        ...
    }
...
//下面进入死循环，正式开启传输（通过eth_rx()），当接受包长度<512，表示收到最后一个包，传输完成。
    for (;;) {
        WATCHDOG_RESET();
#ifdef CONFIG_SHOW_ACTIVITY
        show_activity(1);
#endif
        /*
         *    Check the ethernet for a new packet. The ethernet
         *    receive routine will process it.
         */
        eth_rx();//eth_current->recv(eth_current); 即dm9000_rx ->NetReceive(NetRxPackets[0], RxLen);
/*
        NetReceive ->
        (*udp_packet_handler)((uchar *)ip + IP_UDP_HDR_SIZE,
                        ntohs(ip->udp_dst),
                        src_ip,
                        ntohs(ip->udp_src),
                        ntohs(ip->udp_len) - UDP_HDR_SIZE);
udp_packet_handler在TftpStart()被注册：net_set_udp_handler(TftpHandler);
*/
        /*
         *    Abort if ctrl-c was pressed.
         */
        if (ctrlc()) {
            /* cancel any ARP that may not have completed */
            NetArpWaitPacketIP = 0;

            net_cleanup_loop();
            eth_halt();
            /* Invalidate the last protocol */
            eth_set_last_protocol(BOOTP);

            puts("\nAbort\n");
            /* include a debug print as well incase the debug
               messages are directed to stderr */
            debug_cond(DEBUG_INT_STATE, "--- NetLoop Abort!\n");
            goto done;
        }

        ArpTimeoutCheck();

        /*
         *    Check for a timeout, and run the timeout handler
         *    if we have one.
         */
        if (timeHandler && ((get_timer(0) - timeStart) > timeDelta)) {
            thand_f *x;

#if defined(CONFIG_MII) || defined(CONFIG_CMD_MII)
#if    defined(CONFIG_SYS_FAULT_ECHO_LINK_DOWN)    && \
    defined(CONFIG_STATUS_LED)            && \
    defined(STATUS_LED_RED)
            /*
             * Echo the inverted link state to the fault LED.
             */
            if (miiphy_link(eth_get_dev()->name,
                       CONFIG_SYS_FAULT_MII_ADDR)) {
                status_led_set(STATUS_LED_RED, STATUS_LED_OFF);
            } else {
                status_led_set(STATUS_LED_RED, STATUS_LED_ON);
            }
#endif /* CONFIG_SYS_FAULT_ECHO_LINK_DOWN, ... */
#endif /* CONFIG_MII, ... */
            debug_cond(DEBUG_INT_STATE, "--- NetLoop timeout\n");
            x = timeHandler;
            timeHandler = (thand_f *)0;
            (*x)();
        }


        switch (net_state) {

        case NETLOOP_RESTART:
            NetRestarted = 1;
            goto restart;

        case NETLOOP_SUCCESS:
            net_cleanup_loop();
            if (NetBootFileXferSize > 0) {
                printf("Bytes transferred = %ld (%lx hex)\n",
                    NetBootFileXferSize,
                    NetBootFileXferSize);
                setenv_hex("filesize", NetBootFileXferSize);
                setenv_hex("fileaddr", load_addr);
            }
            if (protocol != NETCONS)
                eth_halt();
            else
                eth_halt_state_only();

            eth_set_last_protocol(protocol);

            ret = NetBootFileXferSize;
            debug_cond(DEBUG_INT_STATE, "--- NetLoop Success!\n");
            goto done;

        case NETLOOP_FAIL:
            net_cleanup_loop();
            /* Invalidate the last protocol */
            eth_set_last_protocol(BOOTP);
            debug_cond(DEBUG_INT_STATE, "--- NetLoop Fail!\n");
            goto done;

        case NETLOOP_CONTINUE:
            continue;
        }
    }




...
}
->



(update.c没有用到)
load_addr在cmd_net.c(227)中根据键入参数重置：
    case 3:    load_addr = simple_strtoul(argv[1], NULL, 16);

#define TFTP_MTU_BLOCKSIZE 1024 在
static unsigned short TftpBlkSizeOption = TFTP_MTU_BLOCKSIZE;
在tftp.c(374)向服务端配置
        /* try for more effic. blk size */
        pkt += sprintf((char *)pkt, "blksize%c%d%c",
                0, TftpBlkSizeOption, 0);