ARC: [cmdline] support External Device Trees from u-boot

void __init setup_arch(char **cmdline_p)

void __init setup_arch(char **cmdline_p)

{

{

	/* make sure that uboot passed pointer to cmdline/dtb is valid */

	if (uboot_tag && is_kernel((unsigned long)uboot_arg))

		panic("Invalid uboot arg\n");

	/* See if u-boot passed an external Device Tree blob */

	machine_desc = setup_machine_fdt(uboot_arg);	/* uboot_tag == 2 */

	if (!machine_desc) {

		/* No, so try the embedded one */

		machine_desc = setup_machine_fdt(__dtb_start);

		machine_desc = setup_machine_fdt(__dtb_start);

		if (!machine_desc)

		if (!machine_desc)

			panic("Embedded DT invalid\n");

			panic("Embedded DT invalid\n");

		/*

		/*

		 * Append uboot cmdline to embedded DT cmdline.

		 * If we are here, it is established that @uboot_arg didn't

		 * point to DT blob. Instead if u-boot says it is cmdline,

		 * Appent to embedded DT cmdline.

		 * setup_machine_fdt() would have populated @boot_command_line

		 * setup_machine_fdt() would have populated @boot_command_line

		 */

		 */

		if (uboot_tag == 1) {

		if (uboot_tag == 1) {

			BUG_ON(is_kernel(unsigned long)uboot_arg);

			/* Ensure a whitespace between the 2 cmdlines */

			/* Ensure a whitespace between the 2 cmdlines */

			strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);

			strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);

			strlcat(boot_command_line, uboot_arg,

			strlcat(boot_command_line, uboot_arg,

				COMMAND_LINE_SIZE);

				COMMAND_LINE_SIZE);

		}

		}

	}

	/* Save unparsed command line copy for /proc/cmdline */

	/* Save unparsed command line copy for /proc/cmdline */

	*cmdline_p = boot_command_line;

	*cmdline_p = boot_command_line;