[PATCH 09/17] overlay: only apply compatible trees

[Sascha Hauer]

This adds support for a global.of_overlay_compatible variable which is a
space separated list of compatible strings. Device tree overlays not
matching any won't be applied (unless the overlay doesn't have a
compatible property at all).

Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 drivers/of/overlay.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index 8f4ee3f0a2..7a89cbe948 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -11,6 +11,9 @@
 #include <common.h>
 #include <of.h>
 #include <errno.h>
+#include <globalvar.h>
+#include <magicvar.h>
+#include <string.h>
 
 static struct device_node *find_target(struct device_node *root,
 				       struct device_node *fragment)
@@ -160,6 +163,33 @@ static int of_overlay_apply_fragment(struct device_node *root,
 	return of_overlay_apply(target, overlay);
 }
 
+static char *of_overlay_compatible;
+
+static bool of_overlay_is_compatible(struct device_node *ovl)
+{
+	char *p, *n, *compatibles;
+	bool res = false;
+
+	if (!of_overlay_compatible || !*of_overlay_compatible)
+		return true;
+	if (!of_find_property(ovl, "compatible", NULL))
+		return true;
+
+	p = compatibles = xstrdup(of_overlay_compatible);
+
+	while ((n = strsep_unescaped(&p, " "))) {
+		if (of_device_is_compatible(ovl, n)) {
+			res = true;
+			break;
+		}
+	}
+
+	free(compatibles);
+
+	return res;
+}
+
+
 /**
  * Apply the overlay on the passed devicetree root
  * @root: the devicetree onto which the overlay will be applied
@@ -172,6 +202,9 @@ int of_overlay_apply_tree(struct device_node *root,
 	struct device_node *fragment;
 	int err = 0;
 
+	if (!of_overlay_is_compatible(overlay))
+		return -ENODEV;
+
 	resolved = of_resolve_phandles(root, overlay);
 	if (!resolved)
 		return -EINVAL;
@@ -250,3 +283,13 @@ int of_register_overlay(struct device_node *overlay)
 {
 	return of_register_fixup(of_overlay_fixup, overlay);
 }
+
+static int of_overlay_init(void)
+{
+	globalvar_add_simple_string("of_overlay_compatible", &of_overlay_compatible);
+
+	return 0;
+}
+device_initcall(of_overlay_init);
+
+BAREBOX_MAGICVAR(global.of_overlay_compatible, "space separated list of compatibles an overlay must match");
-- 
2.29.2