mirror of
https://github.com/brain-hackers/u-boot-brain
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227 lines
6.1 KiB
ReStructuredText
227 lines
6.1 KiB
ReStructuredText
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.. SPDX-License-Identifier: GPL-2.0+
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Implementing shell commands
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===========================
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Command definition
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------------------
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Commands are added to U-Boot by creating a new command structure.
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This is done by first including command.h, then using the U_BOOT_CMD() or the
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U_BOOT_CMD_COMPLETE macro to fill in a struct cmd_tbl structure.
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.. code-block:: c
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U_BOOT_CMD(name, maxargs, repeatable, command, "usage", "help")
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U_BOOT_CMD_COMPLETE(name, maxargs, repeatable, command, "usage, "help", comp)
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name
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The name of the command. This is **not** a string.
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maxargs
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The maximum number of arguments this function takes including
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the command itself.
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repeatable
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Either 0 or 1 to indicate if autorepeat is allowed.
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command
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Pointer to the command function. This is the function that is
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called when the command is issued.
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usage
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Short description. This is a string.
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help
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Long description. This is a string. The long description is
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only available if CONFIG_SYS_LONGHELP is defined.
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comp
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Pointer to the completion function. May be NULL.
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This function is called if the user hits the TAB key while
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entering the command arguments to complete the entry. Command
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completion is only available if CONFIG_AUTO_COMPLETE is defined.
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Sub-command definition
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----------------------
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Likewise an array of struct cmd_tbl holding sub-commands can be created using
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either of the following macros:
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.. code-block:: c
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U_BOOT_CMD_MKENT(name, maxargs, repeatable, command, "usage", "help")
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U_BOOT_CMD_MKENTCOMPLETE(name, maxargs, repeatable, command, "usage, "help", comp)
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This table has to be evaluated in the command function of the main command, e.g.
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.. code-block:: c
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static struct cmd_tbl cmd_sub[] = {
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U_BOOT_CMD_MKENT(foo, CONFIG_SYS_MAXARGS, 1, do_foo, "", ""),
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U_BOOT_CMD_MKENT(bar, CONFIG_SYS_MAXARGS, 1, do_bar, "", ""),
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};
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static int do_cmd(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
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{
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struct cmd_tbl *cp;
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if (argc < 2)
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return CMD_RET_USAGE;
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/* drop sub-command argument */
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argc--;
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argv++;
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cp = find_cmd_tbl(argv[0], cmd_ut_sub, ARRAY_SIZE(cmd_sub));
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if (cp)
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return cp->cmd(cmdtp, flag, argc, argv);
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return CMD_RET_USAGE;
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}
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Command function
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----------------
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The command function pointer has to be of type
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.. code-block:: c
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int (*cmd)(struct cmd_tbl *cmdtp, int flag, int argc, const char *argv[]);
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cmdtp
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Table entry describing the command (see above).
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flag
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A bitmap which may contain the following bits
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* CMD_FLAG_REPEAT - The last command is repeated.
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* CMD_FLAG_BOOTD - The command is called by the bootd command.
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* CMD_FLAG_ENV - The command is called by the run command.
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argc
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Number of arguments including the command.
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argv
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Arguments.
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Allowable return value are:
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CMD_RET_SUCCESS
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The command was successfully executed.
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CMD_RET_FAILURE
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The command failed.
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CMD_RET_USAGE
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The command was called with invalid parameters. This value
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leads to the display of the usage string.
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Completion function
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-------------------
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The completion function pointer has to be of type
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.. code-block:: c
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int (*complete)(int argc, char *const argv[], char last_char,
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int maxv, char *cmdv[]);
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argc
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Number of arguments including the command.
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argv
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Arguments.
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last_char
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The last character in the command line buffer.
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maxv
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Maximum number of possible completions that may be returned by
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the function.
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cmdv
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Used to return possible values for the last argument. The last
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possible completion must be followed by NULL.
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The function returns the number of possible completions (without the terminating
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NULL value).
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Behind the scene
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----------------
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The structure created is named with a special prefix and placed by
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the linker in a special section using the linker lists mechanism
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(see include/linker_lists.h)
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This makes it possible for the final link to extract all commands
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compiled into any object code and construct a static array so the
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command array can be iterated over using the linker lists macros.
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The linker lists feature ensures that the linker does not discard
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these symbols when linking full U-Boot even though they are not
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referenced in the source code as such.
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If a new board is defined do not forget to define the command section
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by writing in u-boot.lds ($(srctree)/board/boardname/u-boot.lds) these
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3 lines:
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.. code-block:: c
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.u_boot_list : {
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KEEP(*(SORT(.u_boot_list*)));
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}
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Writing tests
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-------------
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All new commands should have tests. Tests for existing commands are very
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welcome.
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It is fairly easy to write a test for a command. Enable it in sandbox, and
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then add code that runs the command and checks the output.
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Here is an example:
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.. code-block:: c
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/* Test 'acpi items' command */
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static int dm_test_acpi_cmd_items(struct unit_test_state *uts)
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{
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struct acpi_ctx ctx;
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void *buf;
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buf = malloc(BUF_SIZE);
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ut_assertnonnull(buf);
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ctx.current = buf;
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ut_assertok(acpi_fill_ssdt(&ctx));
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console_record_reset();
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run_command("acpi items", 0);
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ut_assert_nextline("dev 'acpi-test', type 1, size 2");
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ut_assert_nextline("dev 'acpi-test2', type 1, size 2");
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ut_assert_console_end();
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ctx.current = buf;
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ut_assertok(acpi_inject_dsdt(&ctx));
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console_record_reset();
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run_command("acpi items", 0);
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ut_assert_nextline("dev 'acpi-test', type 2, size 2");
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ut_assert_nextline("dev 'acpi-test2', type 2, size 2");
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ut_assert_console_end();
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console_record_reset();
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run_command("acpi items -d", 0);
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ut_assert_nextline("dev 'acpi-test', type 2, size 2");
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ut_assert_nextlines_are_dump(2);
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ut_assert_nextline("%s", "");
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ut_assert_nextline("dev 'acpi-test2', type 2, size 2");
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ut_assert_nextlines_are_dump(2);
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ut_assert_nextline("%s", "");
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ut_assert_console_end();
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return 0;
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}
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DM_TEST(dm_test_acpi_cmd_items, UT_TESTF_SCAN_PDATA | UT_TESTF_SCAN_FDT);
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