[PATCH v5 2/4] block: partitions: populate fwnode

[Daniel Golle]

Assign matching firmware nodes to block partitions in order to allow
them to be referenced e.g. as NVMEM providers.

Signed-off-by: Daniel Golle <daniel@xxxxxxxxxxxxxx>
---
 block/partitions/core.c | 72 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)

diff --git a/block/partitions/core.c b/block/partitions/core.c
index ab76e64f0f6c3..cd54300e1d621 100644
--- a/block/partitions/core.c
+++ b/block/partitions/core.c
@@ -10,6 +10,8 @@
 #include <linux/ctype.h>
 #include <linux/vmalloc.h>
 #include <linux/raid/detect.h>
+#include <linux/property.h>
+
 #include "check.h"
 
 static int (*const check_part[])(struct parsed_partitions *) = {
@@ -281,6 +283,74 @@ static ssize_t whole_disk_show(struct device *dev,
 }
 static const DEVICE_ATTR(whole_disk, 0444, whole_disk_show, NULL);
 
+static bool part_meta_match(const char *attr, const char *member, size_t length)
+{
+	/* check if length of attr exceeds specified maximum length */
+	if (strnlen(attr, length) == length)
+		return false;
+
+	/* return true if strings match */
+	return !strncmp(attr, member, length);
+}
+
+static struct fwnode_handle *find_partition_fwnode(struct block_device *bdev)
+{
+	struct fwnode_handle *fw_parts, *fw_part;
+	struct device *ddev = disk_to_dev(bdev->bd_disk);
+	const char *partname, *uuid;
+	u32 partno;
+	bool got_uuid, got_partname, got_partno;
+
+	fw_parts = device_get_named_child_node(ddev, "partitions");
+	if (!fw_parts)
+		return NULL;
+
+	fwnode_for_each_child_node(fw_parts, fw_part) {
+		got_uuid = false;
+		got_partname = false;
+		got_partno = false;
+		/*
+		 * In case 'uuid' is defined in the partitions firmware node
+		 * require partition meta info being present and the specified
+		 * uuid to match.
+		 */
+		got_uuid = !fwnode_property_read_string(fw_part, "uuid", &uuid);
+		if (got_uuid && (!bdev->bd_meta_info ||
+				 !part_meta_match(uuid, bdev->bd_meta_info->uuid,
+						  PARTITION_META_INFO_UUIDLTH)))
+			continue;
+
+		/*
+		 * In case 'partname' is defined in the partitions firmware node
+		 * require partition meta info being present and the specified
+		 * volname to match.
+		 */
+		got_partname = !fwnode_property_read_string(fw_part, "partname",
+							    &partname);
+		if (got_partname && (!bdev->bd_meta_info ||
+				     !part_meta_match(partname,
+						      bdev->bd_meta_info->volname,
+						      PARTITION_META_INFO_VOLNAMELTH)))
+			continue;
+
+		/*
+		 * In case 'partno' is defined in the partitions firmware node
+		 * the specified partno needs to match.
+		 */
+		got_partno = !fwnode_property_read_u32(fw_part, "partno", &partno);
+		if (got_partno && bdev_partno(bdev) != partno)
+			continue;
+
+		/* Skip if no matching criteria is present in firmware node */
+		if (!got_uuid && !got_partname && !got_partno)
+			continue;
+
+		return fw_part;
+	}
+
+	return NULL;
+}
+
 /*
  * Must be called either with open_mutex held, before a disk can be opened or
  * after all disk users are gone.
@@ -355,6 +425,8 @@ static struct block_device *add_partition(struct gendisk *disk, int partno,
 			goto out_put;
 	}
 
+	device_set_node(pdev, find_partition_fwnode(bdev));
+
 	/* delay uevent until 'holders' subdir is created */
 	dev_set_uevent_suppress(pdev, 1);
 	err = device_add(pdev);
-- 
2.45.2