blspec: add support for devicetree overlays

Read the devicetree-overlay property from the blspec entry and register
the overlays when booting the blspec entry.

Do not fail the boot if an overlay cannot be loaded, because if Linux
fails to boot without an overlay, the base device tree is broken.

Signed-off-by: Michael Tretter <m.tretter@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 61 insertions, 0 deletions

diff --git a/common/blspec.c b/common/blspec.c
index 66e5033e35..fbba2fc78c 100644
--- a/common/blspec.c
+++ b/common/blspec.c
@@ -42,6 +42,62 @@ int blspec_entry_var_set(struct blspec_entry *entry, const char *name,
 			val ? strlen(val) + 1 : 0, 1);
 }
 
+static int blspec_apply_oftree_overlay(char *file, const char *abspath,
+				       int dryrun)
+{
+	int ret = 0;
+	struct fdt_header *fdt;
+	struct device_node *overlay;
+	char *path;
+
+	path = basprintf("%s/%s", abspath, file);
+
+	fdt = read_file(path, NULL);
+	if (!fdt) {
+		pr_warn("unable to read \"%s\"\n", path);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	overlay = of_unflatten_dtb(fdt);
+	free(fdt);
+	if (IS_ERR(overlay)) {
+		ret = PTR_ERR(overlay);
+		goto out;
+	}
+
+	if (dryrun) {
+		pr_info("dry run: skip overlay %s\n", path);
+		of_delete_node(overlay);
+		goto out;
+	}
+
+	ret = of_register_overlay(overlay);
+	if (ret) {
+		pr_warn("cannot register devicetree overlay \"%s\"\n", path);
+		of_delete_node(overlay);
+	}
+
+out:
+	free(path);
+
+	return ret;
+}
+
+static void blspec_apply_oftree_overlays(const char *overlays,
+					 const char *abspath, int dryrun)
+{
+	char *overlay;
+	char *sep, *freep;
+
+	sep = freep = xstrdup(overlays);
+
+	while ((overlay = strsep(&sep, " ")))
+		blspec_apply_oftree_overlay(overlay, abspath, dryrun);
+
+	free(freep);
+}
+
 /*
  * blspec_boot - boot an entry
  *
@@ -54,6 +110,7 @@ static int blspec_boot(struct bootentry *be, int verbose, int dryrun)
 	struct blspec_entry *entry = container_of(be, struct blspec_entry, entry);
 	int ret;
 	const char *abspath, *devicetree, *options, *initrd, *linuximage;
+	const char *overlays;
 	const char *appendroot;
 	struct bootm_data data = {
 		.initrd_address = UIMAGE_INVALID_ADDRESS,
@@ -73,6 +130,7 @@ static int blspec_boot(struct bootentry *be, int verbose, int dryrun)
 	initrd = blspec_entry_var_get(entry, "initrd");
 	options = blspec_entry_var_get(entry, "options");
 	linuximage = blspec_entry_var_get(entry, "linux");
+	overlays = blspec_entry_var_get(entry, "devicetree-overlay");
 
 	if (entry->rootpath)
 		abspath = entry->rootpath;
@@ -92,6 +150,9 @@ static int blspec_boot(struct bootentry *be, int verbose, int dryrun)
 		}
 	}
 
+	if (overlays)
+		blspec_apply_oftree_overlays(overlays, abspath, dryrun);
+
 	if (initrd)
 		data.initrd_file = basprintf("%s/%s", abspath, initrd);