[RFC PATCH 2/2 v1] drivers: core: lists.c: Bind drivers using bootph* property in subnodes

[Moteen Shah <m-shah@ti.com>]

Add a function to scan through all the subnodes of a given node
recusively for bootph* property. If found, propagate it to all
of its parent node up the hierarchy so as to bind the respective
drivers of the nodes in the pre-relocation stage. 

The current model skips the node if there is no bootph* found in
it, even if the property is present in one of the subnodes. The 
issue is tracked in [0].

Signed-off-by: Moteen Shah <m-shah@ti.com>

References: 
[0] https://source.denx.de/u-boot/custodians/u-boot-dm/-/issues/21

---
 drivers/core/lists.c | 88 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 86 insertions(+), 2 deletions(-)

diff --git a/drivers/core/lists.c b/drivers/core/lists.c
index c7be504b6fc..5be556ea951 100644
--- a/drivers/core/lists.c
+++ b/drivers/core/lists.c
@@ -17,6 +17,7 @@
 #include <dm/platdata.h>
 #include <dm/uclass.h>
 #include <dm/util.h>
+#include <fdt_support.h>
 #include <fdtdec.h>
 #include <linux/compiler.h>
 
@@ -196,6 +197,80 @@ static int driver_check_compatible(const struct udevice_id *of_match,
 	return -ENOENT;
 }
 
+/**
+ * scan_and_prop_bootph() - Check if a driver matches a compatible string
+ *
+ * @param of_node:	Parent node for child traversal
+ * @param fdt:	Blob to use
+ */
+static int scan_and_prop_bootph(ofnode node, void *fdt)
+{
+	static int bootph_index = -1;
+	static const char * const bootph_props[] = {
+		"bootph-all",
+		"bootph-some-ram",
+		"bootph-pre-ram",
+		"bootph-pre-sram",
+	};
+	int offset;
+	int ret = -ENOENT;
+	ofnode subnode;
+
+	/* Note the index where bootph-* was found and return success */
+	for (int i = 0; i < ARRAY_SIZE(bootph_props); i++) {
+		if (ofnode_read_bool(node, bootph_props[i])) {
+			bootph_index = i;
+			return 0;
+		}
+	}
+
+	ofnode_for_each_subnode(subnode, node) {
+		if (!ofnode_valid(subnode))
+			continue;
+
+		ret = scan_and_prop_bootph(subnode, fdt);
+		if (ret != -ENOENT && ret)
+			return ret;
+
+		/*
+		 * Break the search if bootph-* is found in any of the subnodes.
+		 * Breaking the loop early helps in avoiding unnecessary traversal
+		 * of the sibling node given that bootph-* has been found in previous
+		 * sibling node.
+		 */
+		if (!ret)
+			break;
+	}
+
+	/* If no bootph-* found then return no such entry */
+	if (ret)
+		return -ENOENT;
+
+	if (bootph_index != -1) {
+		offset = ofnode_to_offset(node);
+		if (offset < 0) {
+			log_err("Failed to get offset %d\n", offset);
+			return -EINVAL;
+		}
+
+		ret = fdt_increase_size(fdt, 32);
+		if (ret) {
+			log_err("Cannot increase FDT size!\n");
+			return ret;
+		}
+
+		ret = fdt_setprop_empty(fdt, offset, bootph_props[bootph_index]);
+		if (ret) {
+			log_err("Failed to add bootph prop to node:%s ret=%d\n",
+				ofnode_get_name(node), ret);
+			return ret;
+		}
+		bootph_index = -1;
+	}
+
+	return ret;
+}
+
 int lists_bind_fdt(struct udevice *parent, ofnode node, struct udevice **devp,
 		   struct driver *drv, bool pre_reloc_only)
 {
@@ -205,6 +280,7 @@ int lists_bind_fdt(struct udevice *parent, ofnode node, struct udevice **devp,
 	struct driver *entry;
 	struct udevice *dev;
 	bool found = false;
+	void *fdt = (void *)gd->fdt_blob;
 	const char *name, *compat_list, *compat;
 	int compat_length, i;
 	int result = 0;
@@ -256,8 +332,16 @@ int lists_bind_fdt(struct udevice *parent, ofnode node, struct udevice **devp,
 		if (pre_reloc_only) {
 			if (!ofnode_pre_reloc(node) &&
 			    !(entry->flags & DM_FLAG_PRE_RELOC)) {
-				log_debug("Skipping device pre-relocation\n");
-				return 0;
+				if (IS_ENABLED(CONFIG_BIND_FROM_CHILD_BOOTPH)) {
+					ret = scan_and_prop_bootph(node, fdt);
+					if (ret) {
+						log_debug("Skipping device pre-relocation\n");
+						return 0;
+					}
+				} else {
+					log_debug("Skipping device pre-relocation\n");
+					return 0;
+				}
 			}
 		}
 
-- 
2.34.1