[fdt] Add the "fdt" command

Allow a Flattened Device Tree blob (DTB) to be provided to a booted
operating system using a script such as:

  #!ipxe
  kernel /images/vmlinuz console=ttyAMA0
  initrd /images/initrd.img
  fdt /images/rk3566-radxa-zero-3e.dtb
  boot

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/config/config.c

@@ -308,6 +308,9 @@ REQUIRE_OBJECT ( image_crypt_cmd );
 #ifdef USB_CMD
 REQUIRE_OBJECT ( usb_cmd );
 #endif
+#ifdef FDT_CMD
+REQUIRE_OBJECT ( fdt_cmd );
+#endif
 
 /*
  * Drag in miscellaneous objects

src/config/defaults/efi.h

@@ -64,10 +64,12 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
 #if defined ( __arm__ ) || defined ( __aarch64__ )
 #define IOAPI_ARM
+#define FDT_CMD
 #endif
 
 #if defined ( __aarch64__ )
 #define	IMAGE_GZIP		/* GZIP image support */
+#define FDT_CMD
 #endif
 
 #if defined ( __loongarch__ )
@@ -76,6 +78,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
 #if defined ( __riscv )
 #define IOAPI_RISCV
+#define FDT_CMD
 #endif
 
 #endif /* CONFIG_DEFAULTS_EFI_H */

src/config/defaults/sbi.h

@@ -32,5 +32,6 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
 #define REBOOT_CMD
 #define POWEROFF_CMD
+#define FDT_CMD
 
 #endif /* CONFIG_DEFAULTS_SBI_H */

src/config/general.h

@@ -173,6 +173,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define IMAGE_ARCHIVE_CMD	/* Archive image management commands */
 #define SHIM_CMD		/* EFI shim command (or dummy command) */
 //#define USB_CMD		/* USB commands */
+//#define FDT_CMD		/* Flattened Device Tree commands */
 
 /*
  * Certificate sources

src/hci/commands/fdt_cmd.c

@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2025 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ * You can also choose to distribute this program under the terms of
+ * the Unmodified Binary Distribution Licence (as given in the file
+ * COPYING.UBDL), provided that you have satisfied its requirements.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#include <getopt.h>
+#include <ipxe/command.h>
+#include <ipxe/parseopt.h>
+#include <usr/imgmgmt.h>
+#include <usr/fdtmgmt.h>
+
+/** @file
+ *
+ * Flattened Device Tree commands
+ *
+ */
+
+/** "fdt" options */
+struct fdt_options {
+	/** Download timeout */
+	unsigned long timeout;
+};
+
+/** "fdt" option list */
+static struct option_descriptor fdt_opts[] = {
+	OPTION_DESC ( "timeout", 't', required_argument,
+		      struct fdt_options, timeout, parse_timeout ),
+};
+
+/** "fdt" command descriptor */
+static struct command_descriptor fdt_cmd =
+	COMMAND_DESC ( struct fdt_options, fdt_opts, 0, 1, "[<uri>]" );
+
+/**
+ * The "fdt" command
+ *
+ * @v argc		Argument count
+ * @v argv		Argument list
+ * @ret rc		Return status code
+ */
+static int fdt_exec ( int argc, char **argv ) {
+	struct fdt_options opts;
+	struct image *image = NULL;
+	char *name_uri;
+	int rc;
+
+	/* Parse options */
+	if ( ( rc = parse_options ( argc, argv, &fdt_cmd, &opts ) ) != 0 )
+		goto err_parse;
+
+	/* Parse name/URI string */
+	name_uri = argv[optind];
+
+	/* Acquire image, if applicable */
+	if ( name_uri && ( ( rc = imgacquire ( name_uri, opts.timeout,
+					       &image ) ) != 0 ) ) {
+		goto err_image;
+	}
+
+	/* (Un)register as FDT */
+	if ( ( rc = imgfdt ( image ) ) != 0 )
+		goto err_fdt;
+
+ err_fdt:
+ err_image:
+ err_parse:
+	return rc;
+}
+
+/** Flattened Device Tree commands */
+struct command fdt_commands[] __command = {
+	{
+		.name = "fdt",
+		.exec = fdt_exec,
+	},
+};