[PATCH 13/17] of_overlay: apply overlays during booting

[Sascha Hauer]

This offers the possibility to load dt overlays on the kernel device
tree during booting. Several globalvars control which device trees
are used. global.of_overlay_dir specifies the directory where overlay
files are expected. global.of_overlay_filepattern specifies file
patterns which the overlay files must match. It is a colon separated
list for multiple file patterns. The patterns may contain '*' and '?'
wildcards. When this variable is empty then no overlays are applied.
global.of_overlay_compatible is used to apply only compatible overlays.
This is also a colon separated list which contains compatible strings.
An overlay is only applied when it's compatible to one of the strings.

Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 drivers/of/overlay.c | 66 ++++++++++++++++++++++++++++++++++++++++++++
 include/of.h         | 17 ++++++++++++
 2 files changed, 83 insertions(+)

diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index c7f640f15f..4362ab2f35 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -16,6 +16,7 @@
 #include <string.h>
 #include <libfile.h>
 #include <fs.h>
+#include <glob.h>
 
 static struct device_node *find_target(struct device_node *root,
 				       struct device_node *fragment)
@@ -327,12 +328,77 @@ int of_register_overlay(struct device_node *overlay)
 	return of_register_fixup(of_overlay_fixup, overlay);
 }
 
+static char *of_overlay_filepattern;
+static char *of_overlay_dir;
+
+const char *of_overlay_get_dir(void)
+{
+	return of_overlay_dir;
+}
+
+void of_overlay_set_dir(const char *path)
+{
+	free(of_overlay_dir);
+	of_overlay_dir = strdup(path);
+}
+
+int of_overlay_apply_dir(struct device_node *root, const char *dir)
+{
+	char *p, *path, *n, *str;
+	int ret = 0, i;
+	glob_t g = {};
+	int globflags = GLOB_NOCHECK;
+
+	if (!dir || !*dir)
+		return 0;
+
+	p = path = strdup(of_overlay_filepattern);
+
+	while ((n = strsep_unescaped(&p, " "))) {
+		str = basprintf("%s/%s", dir, n);
+		if (!str) {
+			ret = -ENOMEM;
+			goto out;
+		}
+
+		ret = glob(str, globflags, NULL, &g);
+
+		free(str);
+
+		if (ret)
+			goto out;
+
+		globflags |= GLOB_APPEND;
+	}
+
+	for (i = 0; i < g.gl_pathc; i++)
+		of_overlay_apply_file(root, g.gl_pathv[i]);
+
+out:
+	globfree(&g);
+
+	free(path);
+
+	return ret;
+}
+
+static int of_overlay_global_fixup(struct device_node *root, void *data)
+{
+	return of_overlay_apply_dir(root, of_overlay_dir);
+}
+
 static int of_overlay_init(void)
 {
 	globalvar_add_simple_string("of_overlay_compatible", &of_overlay_compatible);
+	globalvar_add_simple_string("of_overlay_filepattern", &of_overlay_filepattern);
+	globalvar_add_simple_string("of_overlay_dir", &of_overlay_dir);
+
+	of_register_fixup(of_overlay_global_fixup, NULL);
 
 	return 0;
 }
 device_initcall(of_overlay_init);
 
 BAREBOX_MAGICVAR(global.of_overlay_compatible, "space separated list of compatibles an overlay must match");
+BAREBOX_MAGICVAR(global.of_overlay_filepattern, "space separated list of filepatterns an overlay must match");
+BAREBOX_MAGICVAR(global.of_overlay_dir, "Directory to look for dt overlays");
diff --git a/include/of.h b/include/of.h
index 9457fed9c0..4be6af8f4b 100644
--- a/include/of.h
+++ b/include/of.h
@@ -1037,6 +1037,9 @@ int of_process_overlay(struct device_node *root,
 int of_overlay_pre_load_firmware(struct device_node *root, struct device_node *overlay);
 int of_overlay_load_firmware(void);
 void of_overlay_load_firmware_clear(void);
+int of_overlay_apply_dir(struct device_node *root, const char *dir);
+const char *of_overlay_get_dir(void);
+void of_overlay_set_dir(const char *path);
 #else
 static inline struct device_node *of_resolve_phandles(struct device_node *root,
 					const struct device_node *overlay)
@@ -1085,6 +1088,20 @@ static inline void of_overlay_load_firmware_clear(void)
 {
 }
 
+static inline int of_overlay_apply_dir(struct device_node *root, const char *dir)
+{
+	return 0;
+}
+
+static inline const char *of_overlay_get_dir(void)
+{
+	return NULL;
+}
+
+static inline void of_overlay_set_dir(const char *path)
+{
+}
+
 #endif
 
 #endif /* __OF_H */
-- 
2.29.2