+Command definition
+------------------
Commands are added to U-Boot by creating a new command structure.
-This is done by first including command.h, then using the U_BOOT_CMD() macro
-to fill in a cmd_tbl_t struct.
+This is done by first including command.h, then using the U_BOOT_CMD() or the
+U_BOOT_CMD_COMPLETE macro to fill in a struct cmd_tbl struct.
-U_BOOT_CMD(name,maxargs,repeatable,command,"usage","help")
+U_BOOT_CMD(name, maxargs, repeatable, command, "usage", "help")
+U_BOOT_CMD_COMPLETE(name, maxargs, repeatable, command, "usage, "help", comp)
-name: is the name of the commad. THIS IS NOT a string.
-maxargs: the maximum number of arguments this function takes
-repeatable: either 0 or 1 to indicate if autorepeat is allowed
-command: Function pointer (*cmd)(struct cmd_tbl_s *, int, int, char *[]);
-usage: Short description. This is a string
-help: Long description. This is a string
+name: The name of the command. THIS IS NOT a string.
+maxargs: The maximum number of arguments this function takes including
+ the command itself.
-**** Behind the scene ******
+repeatable: Either 0 or 1 to indicate if autorepeat is allowed.
-The structure created is named with a special prefix (__u_boot_list_cmd_)
-and placed by the linker in a special section.
+command: Pointer to the command function. This is the function that is
+ called when the command is issued.
+
+usage: Short description. This is a string.
+
+help: Long description. This is a string. The long description is
+ only available if CONFIG_SYS_LONGHELP is defined.
+
+comp: Pointer to the completion function. May be NULL.
+ This function is called if the user hits the TAB key while
+ entering the command arguments to complete the entry. Command
+ completion is only available if CONFIG_AUTO_COMPLETE is defined.
+
+Sub-command definition
+----------------------
+
+Likewise an array of struct cmd_tbl holding sub-commands can be created using either
+of the following macros:
+
+* U_BOOT_CMD_MKENT(name, maxargs, repeatable, command, "usage", "help")
+* U_BOOT_CMD_MKENTCOMPLETE(name, maxargs, repeatable, command, "usage, "help",
+ comp)
+
+This table has to be evaluated in the command function of the main command, e.g.
+
+ static struct cmd_tbl cmd_sub[] = {
+ U_BOOT_CMD_MKENT(foo, CONFIG_SYS_MAXARGS, 1, do_foo, "", ""),
+ U_BOOT_CMD_MKENT(bar, CONFIG_SYS_MAXARGS, 1, do_bar, "", ""),
+ };
+
+ static int do_cmd(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
+ {
+ struct cmd_tbl *cp;
+
+ if (argc < 2)
+ return CMD_RET_USAGE;
+
+ /* drop sub-command argument */
+ argc--;
+ argv++;
+
+ cp = find_cmd_tbl(argv[0], cmd_ut_sub, ARRAY_SIZE(cmd_sub));
+
+ if (cp)
+ return cp->cmd(cmdtp, flag, argc, argv);
+
+ return CMD_RET_USAGE;
+ }
+
+Command function
+----------------
+
+The command function pointer has to be of type
+int (*cmd)(struct cmd_tbl *cmdtp, int flag, int argc, const char *argv[]);
+
+cmdtp: Table entry describing the command (see above).
+
+flag: A bitmap which may contain the following bit:
+ CMD_FLAG_REPEAT - The last command is repeated.
+ CMD_FLAG_BOOTD - The command is called by the bootd command.
+ CMD_FLAG_ENV - The command is called by the run command.
+
+argc: Number of arguments including the command.
+
+argv: Arguments.
+
+Allowable return value are:
+
+CMD_RET_SUCCESS The command was successfully executed.
+
+CMD_RET_FAILURE The command failed.
+
+CMD_RET_USAGE The command was called with invalid parameters. This value
+ leads to the display of the usage string.
+
+Completion function
+-------------------
+
+The completion function pointer has to be of type
+int (*complete)(int argc, char *const argv[], char last_char,
+ int maxv, char *cmdv[]);
+
+argc: Number of arguments including the command.
+
+argv: Arguments.
+
+last_char: The last character in the command line buffer.
+
+maxv: Maximum number of possible completions that may be returned by
+ the function.
+
+cmdv: Used to return possible values for the last argument. The last
+ possible completion must be followed by NULL.
+
+The function returns the number of possible completions (without the terminating
+NULL value).
+
+Behind the scene
+----------------
+
+The structure created is named with a special prefix and placed by
+the linker in a special section using the linker lists mechanism
+(see include/linker_lists.h)
This makes it possible for the final link to extract all commands
compiled into any object code and construct a static array so the
-command can be found in an array starting at _u_boot_list_cmd__start.
+command array can be iterated over using the linker lists macros.
-To ensure that the linker does not discard these symbols when linking
-full U-Boot we generate a list of all the commands we have built (based
-on the sections mentioned above) and use that to force the linker to
-first enter the symbol as undefined in the output object so that there
-is then a need for the symbol to be kept (this is the UNDEF_SYM logic in
-the Makefile).
+The linker lists feature ensures that the linker does not discard
+these symbols when linking full U-Boot even though they are not
+referenced in the source code as such.
If a new board is defined do not forget to define the command section
-by writing in u-boot.lds ($(TOPDIR)/board/boardname/u-boot.lds) these
+by writing in u-boot.lds ($(srctree)/board/boardname/u-boot.lds) these
3 lines:
.u_boot_list : {
- #include "u-boot.lst";
+ KEEP(*(SORT(.u_boot_list*)));
}
projects / oweals / u-boot.git / blobdiff