[PATCH v3 2/4] block: partitions: populate fwnode

[Daniel Golle <daniel@xxxxxxxxxxxxxx>]

Let block partitions to be represented by a firmware node and hence
allow them to being referenced e.g. for use with blk-nvmem.

Signed-off-by: Daniel Golle <daniel@xxxxxxxxxxxxxx>
---
 block/partitions/core.c | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/block/partitions/core.c b/block/partitions/core.c
index ab76e64f0f6c..f88829e254e6 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 +283,42 @@ static ssize_t whole_disk_show(struct device *dev,
 }
 static const DEVICE_ATTR(whole_disk, 0444, whole_disk_show, NULL);
 
+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;
+
+	fw_parts = device_get_named_child_node(ddev, "partitions");
+	if (!fw_parts)
+		fw_parts = device_get_named_child_node(ddev->parent, "partitions");
+
+	if (!fw_parts)
+		return NULL;
+
+	fwnode_for_each_child_node(fw_parts, fw_part) {
+		if (!fwnode_property_read_string(fw_part, "uuid", &uuid) &&
+		    (!bdev->bd_meta_info || strlen(uuid) > PARTITION_META_INFO_UUIDLTH ||
+		     strncmp(uuid, bdev->bd_meta_info->uuid, PARTITION_META_INFO_UUIDLTH)))
+			continue;
+
+		if (!fwnode_property_read_string(fw_part, "partname", &partname) &&
+		    (!bdev->bd_meta_info || strlen(uuid) > PARTITION_META_INFO_VOLNAMELTH ||
+		     strncmp(partname, bdev->bd_meta_info->volname,
+			     PARTITION_META_INFO_VOLNAMELTH)))
+			continue;
+
+		if (!fwnode_property_read_u32(fw_part, "partno", &partno) &&
+		    bdev_partno(bdev) != 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 +393,8 @@ 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