学步园

    记得以前曾经做过WINCE下面利用EBOOT从SD卡读取文件系统更新NAND种的文件，已实现在文件系统被破坏的情况下，用户可以自己还原，那么如果是LINUX系统呢？

    思路是一样：UBOOT启动至第2阶段（没有自启动系统）-----------判断是否更新内核和文件系统--------------如果接收到了用户命令则从SD卡拷贝文件写入NAND指定位置；反之，则启动系统

    重点是怎么接收到用户指令和从SD卡种拷贝文件；

    在UBOOT运行至第2阶段的时候：lib_arm/board.c中调用common/main.c下的main_loop函数

void main_loop (void)<br /> {<br /> #ifndef CFG_HUSH_PARSER<br /> static char lastcommand[CFG_CBSIZE] = { 0, };<br /> int len;<br /> int rc = 1;<br /> int flag;<br /> #endif</p> <p>#if defined(CONFIG_BOOTDELAY) && (CONFIG_BOOTDELAY >= 0)<br /> char *s;<br /> int bootdelay;<br /> #endif<br /> #ifdef CONFIG_PREBOOT<br /> char *p;<br /> #endif<br /> #ifdef CONFIG_BOOTCOUNT_LIMIT<br /> unsigned long bootcount = 0;<br /> unsigned long bootlimit = 0;<br /> char *bcs;<br /> char bcs_set[16];<br /> #endif /* CONFIG_BOOTCOUNT_LIMIT */</p> <p>#if defined(CONFIG_VFD) && defined(VFD_TEST_LOGO)<br /> ulong bmp = 0; /* default bitmap */<br /> extern int trab_vfd (ulong bitmap);</p> <p>#ifdef CONFIG_MODEM_SUPPORT<br /> if (do_mdm_init)<br /> bmp = 1; /* alternate bitmap */<br /> #endif<br /> trab_vfd (bmp);<br /> #endif /* CONFIG_VFD && VFD_TEST_LOGO */</p> <p>#ifdef CONFIG_BOOTCOUNT_LIMIT<br /> bootcount = bootcount_load();<br /> bootcount++;<br /> bootcount_store (bootcount);<br /> sprintf (bcs_set, "%lu", bootcount);<br /> setenv ("bootcount", bcs_set);<br /> bcs = getenv ("bootlimit");<br /> bootlimit = bcs ? simple_strtoul (bcs, NULL, 10) : 0;<br /> #endif /* CONFIG_BOOTCOUNT_LIMIT */</p> <p>#ifdef CONFIG_MODEM_SUPPORT<br /> debug ("DEBUG: main_loop: do_mdm_init=%d/n", do_mdm_init);<br /> if (do_mdm_init) {<br /> char *str = strdup(getenv("mdm_cmd"));<br /> setenv ("preboot", str); /* set or delete definition */<br /> if (str != NULL)<br /> free (str);<br /> mdm_init(); /* wait for modem connection */<br /> }<br /> #endif /* CONFIG_MODEM_SUPPORT */</p> <p>#ifdef CONFIG_VERSION_VARIABLE<br /> {<br /> extern char version_string[];</p> <p> setenv ("ver", version_string); /* set version variable */<br /> }<br /> #endif /* CONFIG_VERSION_VARIABLE */</p> <p>#ifdef CFG_HUSH_PARSER<br /> u_boot_hush_start ();<br /> #endif</p> <p>#ifdef CONFIG_AUTO_COMPLETE<br /> install_auto_complete();<br /> #endif</p> <p>#ifdef CONFIG_PREBOOT<br /> if ((p = getenv ("preboot")) != NULL) {<br /> # ifdef CONFIG_AUTOBOOT_KEYED<br /> int prev = disable_ctrlc(1); /* disable Control C checking */<br /> # endif</p> <p># ifndef CFG_HUSH_PARSER<br /> run_command (p, 0);<br /> # else<br /> parse_string_outer(p, FLAG_PARSE_SEMICOLON |<br /> FLAG_EXIT_FROM_LOOP);<br /> # endif</p> <p># ifdef CONFIG_AUTOBOOT_KEYED<br /> disable_ctrlc(prev); /* restore Control C checking */<br /> # endif<br /> }<br /> #endif /* CONFIG_PREBOOT */</p> <p>#if defined(CONFIG_BOOTDELAY) && (CONFIG_BOOTDELAY >= 0)<br /> s = getenv ("bootdelay");<br /> bootdelay = s ? (int)simple_strtol(s, NULL, 10) : CONFIG_BOOTDELAY;</p> <p> debug ("### main_loop entered: bootdelay=%d/n/n", bootdelay);</p> <p># ifdef CONFIG_BOOT_RETRY_TIME<br /> init_cmd_timeout ();<br /> # endif /* CONFIG_BOOT_RETRY_TIME */</p> <p>#ifdef CONFIG_POST<br /> if (gd->flags & GD_FLG_POSTFAIL) {<br /> s = getenv("failbootcmd");<br /> }<br /> else<br /> #endif /* CONFIG_POST */<br /> #ifdef CONFIG_BOOTCOUNT_LIMIT<br /> if (bootlimit && (bootcount > bootlimit)) {<br /> printf ("Warning: Bootlimit (%u) exceeded. Using altbootcmd./n",<br /> (unsigned)bootlimit);<br /> s = getenv ("altbootcmd");<br /> }<br /> else<br /> #endif /* CONFIG_BOOTCOUNT_LIMIT */<br /> s = getenv ("bootcmd");</p> <p> debug ("### main_loop: bootcmd=/"%s/"/n", s ? s : "<UNDEFINED>");</p> <p> if (bootdelay >= 0 && s && !abortboot (bootdelay)) {<br /> # ifdef CONFIG_AUTOBOOT_KEYED<br /> int prev = disable_ctrlc(1); /* disable Control C checking */<br /> # endif</p> <p># ifndef CFG_HUSH_PARSER<br /> run_command (s, 0);<br /> # else<br /> parse_string_outer(s, FLAG_PARSE_SEMICOLON |<br /> FLAG_EXIT_FROM_LOOP);<br /> # endif</p> <p># ifdef CONFIG_AUTOBOOT_KEYED<br /> disable_ctrlc(prev); /* restore Control C checking */<br /> # endif<br /> }</p> <p># ifdef CONFIG_MENUKEY<br /> if (menukey == CONFIG_MENUKEY) {<br /> s = getenv("menucmd");<br /> if (s) {<br /> # ifndef CFG_HUSH_PARSER<br /> run_command (s, 0);<br /> # else<br /> parse_string_outer(s, FLAG_PARSE_SEMICOLON |<br /> FLAG_EXIT_FROM_LOOP);<br /> # endif<br /> }<br /> }<br /> #endif /* CONFIG_MENUKEY */<br /> #endif /* CONFIG_BOOTDELAY */</p> <p>#ifdef CONFIG_AMIGAONEG3SE<br /> {<br /> extern void video_banner(void);<br /> video_banner();<br /> }<br /> #endif</p> <p> /*<br /> * Main Loop for Monitor Command Processing<br /> */<br /> #ifdef CFG_HUSH_PARSER<br /> parse_file_outer();<br /> /* This point is never reached */<br /> for (;;);<br /> #else<br /> for (;;) {<br /> #ifdef CONFIG_BOOT_RETRY_TIME<br /> if (rc >= 0) {<br /> /* Saw enough of a valid command to<br /> * restart the timeout.<br /> */<br /> reset_cmd_timeout();<br /> }<br /> #endif<br /> len = readline (CFG_PROMPT);</p> <p> flag = 0; /* assume no special flags for now */<br /> if (len > 0)<br /> strcpy (lastcommand, console_buffer);<br /> else if (len == 0)<br /> flag |= CMD_FLAG_REPEAT;<br /> #ifdef CONFIG_BOOT_RETRY_TIME<br /> else if (len == -2) {<br /> /* -2 means timed out, retry autoboot<br /> */<br /> puts ("/nTimed out waiting for command/n");<br /> # ifdef CONFIG_RESET_TO_RETRY<br /> /* Reinit board to run initialization code again */<br /> do_reset (NULL, 0, 0, NULL);<br /> # else<br /> return; /* retry autoboot */<br /> # endif<br /> }<br /> #endif</p> <p> if (len == -1)<br /> puts ("<INTERRUPT>/n");<br /> else<br /> rc = run_command (lastcommand, flag);</p> <p> if (rc <= 0) {<br /> /* invalid command or not repeatable, forget it */<br /> lastcommand[0] = 0;<br /> }<br /> }<br /> #endif /*CFG_HUSH_PARSER*/<br /> }

这里会做两个判断，调用static __inline__ int abortboot(int bootdelay)
函数，判断是否有用户中断，如果有则进入死循环，接收用户命令，并根据命令，调用相应的函数处理

如果你下载过android系统文件，你肯定知道会有类似nand write c0008000 600000 300000等命令，来写入文件；上面run_command函数 这个函数就是处理类似这样的命令，具体实现可以查看代码各函数功能，

既然是让客户自更新，我们也不能让客户按照我们测试人员一样，打开串口信息，一行行敲命令吧，那就完蛋了。。。。

所以我们可以在这里加入我们的更新系统的提示！-------------（1）用户触发更新系统中断；（2）接收中断，调用run_command函数处理事件（将SD卡种文件写入NAND指定位置）

对于步骤1；我们可以采用读取某个I/O口状态来判断是否更新系统；

对于步骤2：关键是加入我们的处理函数，告诉系统“要从SD卡读取文件写入NAND”

这里就需要了解下run_command函数了

int run_command (const char *cmd, int flag)<br /> {<br /> cmd_tbl_t *cmdtp;<br /> char cmdbuf[CFG_CBSIZE]; /* working copy of cmd */<br /> char *token; /* start of token in cmdbuf */<br /> char *sep; /* end of token (separator) in cmdbuf */<br /> char finaltoken[CFG_CBSIZE];<br /> char *str = cmdbuf;<br /> char *argv[CFG_MAXARGS + 1]; /* NULL terminated */<br /> int argc, inquotes;<br /> int repeatable = 1;<br /> int rc = 0;</p> <p>#ifdef DEBUG_PARSER<br /> printf ("[RUN_COMMAND] cmd[%p]=/"", cmd);<br /> puts (cmd ? cmd : "NULL"); /* use puts - string may be loooong */<br /> puts ("/"/n");<br /> #endif</p> <p> clear_ctrlc(); /* forget any previous Control C */</p> <p> if (!cmd || !*cmd) {<br /> return -1; /* empty command */<br /> }</p> <p> if (strlen(cmd) >= CFG_CBSIZE) {<br /> puts ("## Command too long!/n");<br /> return -1;<br /> }</p> <p> strcpy (cmdbuf, cmd);</p> <p> /* Process separators and check for invalid<br /> * repeatable commands<br /> */</p> <p>#ifdef DEBUG_PARSER<br /> printf ("[PROCESS_SEPARATORS] %s/n", cmd);<br /> #endif<br /> while (*str) {</p> <p> /*<br /> * Find separator, or string end<br /> * Allow simple escape of ';' by writing "/;"<br /> */<br /> for (inquotes = 0, sep = str; *sep; sep++) {<br /> if ((*sep=='/'') &&<br /> (*(sep-1) != '//'))<br /> inquotes=!inquotes;</p> <p> if (!inquotes &&<br /> (*sep == ';') && /* separator */<br /> ( sep != str) && /* past string start */<br /> (*(sep-1) != '//')) /* and NOT escaped */<br /> break;<br /> }</p> <p> /*<br /> * Limit the token to data between separators<br /> */<br /> token = str;<br /> if (*sep) {<br /> str = sep + 1; /* start of command for next pass */<br /> *sep = '/0';<br /> }<br /> else<br /> str = sep; /* no more commands for next pass */<br /> #ifdef DEBUG_PARSER<br /> printf ("token: /"%s/"/n", token);<br /> #endif</p> <p> /* find macros in this token and replace them */<br /> process_macros (token, finaltoken);</p> <p> /* Extract arguments */<br /> if ((argc = parse_line (finaltoken, argv)) == 0) {<br /> rc = -1; /* no command at all */<br /> continue;<br /> }</p> <p> /* Look up command in command table */<br /> if ((cmdtp = find_cmd(argv[0])) == NULL) {<br /> printf ("Unknown command '%s' - try 'help'/n", argv[0]);<br /> rc = -1; /* give up after bad command */<br /> continue;<br /> }</p> <p> /* found - check max args */<br /> if (argc > cmdtp->maxargs) {<br /> printf ("Usage:/n%s/n", cmdtp->usage);<br /> rc = -1;<br /> continue;<br /> }</p> <p>#if defined(CONFIG_CMD_BOOTD)<br /> /* avoid "bootd" recursion */<br /> if (cmdtp->cmd == do_bootd) {<br /> #ifdef DEBUG_PARSER<br /> printf ("[%s]/n", finaltoken);<br /> #endif<br /> if (flag & CMD_FLAG_BOOTD) {<br /> puts ("'bootd' recursion detected/n");<br /> rc = -1;<br /> continue;<br /> } else {<br /> flag |= CMD_FLAG_BOOTD;<br /> }<br /> }<br /> #endif</p> <p> /* OK - call function to do the command */<br /> if ((cmdtp->cmd) (cmdtp, flag, argc, argv) != 0) {<br /> rc = -1;<br /> }</p> <p> repeatable &= cmdtp->repeatable;</p> <p> /* Did the user stop this? */<br /> if (had_ctrlc ())<br /> return -1; /* if stopped then not repeatable */<br /> }</p> <p> return rc ? rc : repeatable;<br /> }

流程：处理宏定义，分析命令和参数 ， 查找是否有命令 ，执行命令

我们可以通过nand write c0008000 600000 300000这个命令来了解整个过程

common/cmd_nand.c下 U_BOOT_CMD(nand, CONFIG_SYS_MAXARGS, 1, do_nand..............................下有命令的说明

相应的NAND驱动中就有具体的实现；

重要函数：

/* Look up command in command table */
  if ((cmdtp = find_cmd(argv[0])) == NULL)

cmd_tbl_t *find_cmd (const char *cmd)
这里会遍历所有结构体集合

48 . = .;<br /> 49 __u_boot_cmd_start = .;<br /> 50 .u_boot_cmd : { *(.u_boot_cmd) }<br /> 51 __u_boot_cmd_end = .;</p> <p>

find_cmd 函数原型

cmd_tbl_t *find_cmd (const char *cmd)<br /> {<br /> cmd_tbl_t *cmdtp;<br /> cmd_tbl_t *cmdtp_temp = &__u_boot_cmd_start; /*Init value */<br /> const char *p;<br /> int len;<br /> int n_found = 0;<br /> /*<br /> * Some commands allow length modifiers (like "cp.b");<br /> * compare command name only until first dot.<br /> */<br /> len = ((p = strchr(cmd, '.')) == NULL) ? strlen (cmd) : (p - cmd);<br /> for (cmdtp = &__u_boot_cmd_start;<br /> cmdtp != &__u_boot_cmd_end;<br /> cmdtp++) {<br /> if (strncmp (cmd, cmdtp->name, len) == 0) {<br /> if (len == strlen (cmdtp->name))<br /> return cmdtp; /* full match */<br /> cmdtp_temp = cmdtp; /* abbreviated command ? */<br /> n_found++;<br /> }<br /> }<br /> if (n_found == 1) { /* exactly one match */<br /> return cmdtp_temp;<br /> }<br /> return NULL; /* not found or ambiguous command */<br /> }</p> <p>

所以我们可以定义我们自己的U_BOOT_CMD

类似

U_BOOT_CMD(
 SD, 2, 1, DO_SD,
 "xxxxxxxx/n",
 "xxxxxxxxxxx /n"
 "     -xxxxxxxxxx/n"
);

然后定义DO_SD函数即可