fastboot: introduce 'oem board' subcommand

Currently, fastboot protocol in U-Boot has no opportunity
to execute vendor custom code with verifed boot. This patch
introduce new fastboot subcommand fastboot oem board:<cmd>,
which allow to run custom oem_board function.

Default implementation is __weak. Vendor must redefine it in
board/ folder with his own logic.

For example, some vendors have their custom nand/emmc partition
flashing or erasing. Here some typical command for such use cases:

- flashing:

  $ fastboot stage bootloader.img
  $ fastboot oem board:write_bootloader

- erasing:

  $ fastboot oem board:erase_env

Signed-off-by: Alexey Romanov <avromanov@salutedevices.com>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Reviewed-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
Link: https://lore.kernel.org/r/20240418100129.1691822-2-avromanov@salutedevices.com
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>

drivers/fastboot/fb_command.c

@@ -43,6 +43,7 @@ static void oem_format(char *, char *);
 static void oem_partconf(char *, char *);
 static void oem_bootbus(char *, char *);
 static void oem_console(char *, char *);
+static void oem_board(char *, char *);
 static void run_ucmd(char *, char *);
 static void run_acmd(char *, char *);
 
@@ -114,6 +115,10 @@ static const struct {
 		.command = "oem console",
 		.dispatch = CONFIG_IS_ENABLED(FASTBOOT_CMD_OEM_CONSOLE, (oem_console), (NULL))
 	},
+	[FASTBOOT_COMMAND_OEM_BOARD] = {
+		.command = "oem board",
+		.dispatch = CONFIG_IS_ENABLED(FASTBOOT_OEM_BOARD, (oem_board), (NULL))
+	},
 	[FASTBOOT_COMMAND_UCMD] = {
 		.command = "UCmd",
 		.dispatch = CONFIG_IS_ENABLED(FASTBOOT_UUU_SUPPORT, (run_ucmd), (NULL))
@@ -549,3 +554,28 @@ static void __maybe_unused oem_console(char *cmd_parameter, char *response)
 	else
 		fastboot_response(FASTBOOT_MULTIRESPONSE_START, response, NULL);
 }
+
+/**
+ * fastboot_oem_board() - Execute the OEM board command. This is default
+ * weak implementation, which may be overwritten in board/ files.
+ *
+ * @cmd_parameter: Pointer to command parameter
+ * @data: Pointer to fastboot input buffer
+ * @size: Size of the fastboot input buffer
+ * @response: Pointer to fastboot response buffer
+ */
+void __weak fastboot_oem_board(char *cmd_parameter, void *data, u32 size, char *response)
+{
+	fastboot_fail("oem board function not defined", response);
+}
+
+/**
+ * oem_board() - Execute the OEM board command
+ *
+ * @cmd_parameter: Pointer to command parameter
+ * @response: Pointer to fastboot response buffer
+ */
+static void __maybe_unused oem_board(char *cmd_parameter, char *response)
+{
+	fastboot_oem_board(cmd_parameter, (void *)fastboot_buf_addr, image_size, response);
+}