fit: Refactor config node handling

This patch makes some minor refactoring to the way the FIT parser
handles config nodes. A lot of this code was written in the dawn age of
depthcharge when its device tree library wasn't as well-stocked yet, so
some of it can be rewritten nicer with more high-level primitives.
There's no point in storing both the string name and the actual FDT node
of a FIT image node separately, since the latter also contains the
former, so remove that. Also eliminate code for the case of not having
an FDT (which makes no sense), and move some more FDT validity/compat
checking into fit_update_compat() (mostly in anticipation of later
changes).

This patch was adapted from depthcharge's http://crosreview.com/1553456
with a couple of modifications specific to coreboot's custom FIT loading
code.

Change-Id: Ia79e0fd0e1159c4aca64c453b82a0379b133350d
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32870
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/lib/fit_payload.c b/src/lib/fit_payload.c
index e0158f2..4bc6622 100644
--- a/src/lib/fit_payload.c
+++ b/src/lib/fit_payload.c
@@ -176,37 +176,34 @@
 
 	struct fit_config_node *config = fit_load(data);
 
-	if (!config || !config->kernel_node) {
+	if (!config) {
 		printk(BIOS_ERR, "ERROR: Could not load FIT\n");
 		rdev_munmap(prog_rdev(payload), data);
 		return;
 	}
 
-	if (config->fdt_node) {
-		dt = fdt_unflatten(config->fdt_node->data);
-		if (!dt) {
-			printk(BIOS_ERR,
-			       "ERROR: Failed to unflatten the FDT.\n");
-			rdev_munmap(prog_rdev(payload), data);
-			return;
-		}
-
-		dt_apply_fixups(dt);
-
-		/* Insert coreboot specific information */
-		add_cb_fdt_data(dt);
-
-		/* Update device_tree */
-#if defined(CONFIG_LINUX_COMMAND_LINE)
-		fit_update_chosen(dt, (char *)CONFIG_LINUX_COMMAND_LINE);
-#endif
-		fit_update_memory(dt);
+	dt = fdt_unflatten(config->fdt->data);
+	if (!dt) {
+		printk(BIOS_ERR, "ERROR: Failed to unflatten the FDT.\n");
+		rdev_munmap(prog_rdev(payload), data);
+		return;
 	}
 
+	dt_apply_fixups(dt);
+
+	/* Insert coreboot specific information */
+	add_cb_fdt_data(dt);
+
+	/* Update device_tree */
+#if defined(CONFIG_LINUX_COMMAND_LINE)
+	fit_update_chosen(dt, (char *)CONFIG_LINUX_COMMAND_LINE);
+#endif
+	fit_update_memory(dt);
+
 	/* Collect infos for fit_payload_arch */
-	kernel.size = config->kernel_node->size;
+	kernel.size = config->kernel->size;
 	fdt.size = dt ? dt_flat_size(dt) : 0;
-	initrd.size = config->ramdisk_node ? config->ramdisk_node->size : 0;
+	initrd.size = config->ramdisk ? config->ramdisk->size : 0;
 
 	/* Invoke arch specific payload placement and fixups */
 	if (!fit_payload_arch(payload, config, &kernel, &fdt, &initrd)) {
@@ -216,17 +213,15 @@
 		return;
 	}
 
-	/* Load the images to given position */
-	if (config->fdt_node) {
-		/* Update device_tree */
-		if (config->ramdisk_node)
-			fit_add_ramdisk(dt, (void *)initrd.offset, initrd.size);
+	/* Update ramdisk location in FDT */
+	if (config->ramdisk)
+		fit_add_ramdisk(dt, (void *)initrd.offset, initrd.size);
 
-		pack_fdt(&fdt, dt);
-	}
+	/* Repack FDT for handoff to kernel */
+	pack_fdt(&fdt, dt);
 
-	if (config->ramdisk_node &&
-	    extract(&initrd, config->ramdisk_node)) {
+	if (config->ramdisk &&
+	    extract(&initrd, config->ramdisk)) {
 		printk(BIOS_ERR, "ERROR: Failed to extract initrd\n");
 		prog_set_entry(payload, NULL, NULL);
 		rdev_munmap(prog_rdev(payload), data);
@@ -235,7 +230,7 @@
 
 	timestamp_add_now(TS_KERNEL_DECOMPRESSION);
 
-	if (extract(&kernel, config->kernel_node)) {
+	if (extract(&kernel, config->kernel)) {
 		printk(BIOS_ERR, "ERROR: Failed to extract kernel\n");
 		prog_set_entry(payload, NULL, NULL);
 		rdev_munmap(prog_rdev(payload), data);