[PATCH V3 3/4] mtd: partitions: add of_match_table parser matching

[Rafał Miłecki]

From: Brian Norris <computersforpeace at gmail.com>

Partition parsers can now provide an of_match_table to enable
flash<-->parser matching via device tree.

This support is currently limited to built-in parsers as it uses
request_module() and friends. This should be sufficient for most cases
though as compiling parsers as modules isn't a common choice.

Signed-off-by: Brian Norris <computersforpeace at gmail.com>
Signed-off-by: Rafał Miłecki <rafal at milecki.pl>
Acked-by: Brian Norris <computersforpeac at gmail.com>
---
This is based on Brian's patches:
[RFC PATCH 4/7] mtd: add of_match_mtd_parser() and of_mtd_match_mtd_parser() helpers
[RFC PATCH 6/7] RFC: mtd: partitions: enable of_match_table matching

V1: Put helpers in mtdpart.c instead of drivers/of/of_mtd.c
    Merge helpers into a single of_mtd_match_mtd_parser
V3: Add a simple comment to note we will need the best match in the future
---
 drivers/mtd/mtdpart.c          | 48 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/mtd/partitions.h |  1 +
 2 files changed, 49 insertions(+)

diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index 73c52f1a2e4c..0d3cc1e79014 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -861,6 +861,42 @@ static int mtd_part_do_parse(struct mtd_part_parser *parser,
 	return ret;
 }
 
+static bool of_mtd_match_mtd_parser(struct mtd_info *mtd,
+				    struct mtd_part_parser *parser)
+{
+	struct device_node *np;
+	bool ret;
+
+	np = mtd_get_of_node(mtd);
+	np = of_get_child_by_name(np, "partitions");
+
+	ret = !!of_match_node(parser->of_match_table, np);
+
+	of_node_put(np);
+
+	return ret;
+}
+
+static struct mtd_part_parser *mtd_part_get_parser_by_of(struct mtd_info *mtd)
+{
+	struct mtd_part_parser *p, *ret = NULL;
+
+	spin_lock(&part_parser_lock);
+
+	/* TODO: Pick parser with the best match (score) */
+	list_for_each_entry(p, &part_parsers, list) {
+		if (of_mtd_match_mtd_parser(mtd, p) &&
+				try_module_get(p->owner)) {
+			ret = p;
+			break;
+		}
+	}
+
+	spin_unlock(&part_parser_lock);
+
+	return ret;
+}
+
 /**
  * parse_mtd_partitions - parse MTD partitions
  * @master: the master partition (describes whole MTD device)
@@ -913,6 +949,18 @@ int parse_mtd_partitions(struct mtd_info *master, const char *const *types,
 		if (ret < 0 && !err)
 			err = ret;
 	}
+
+	parser = mtd_part_get_parser_by_of(master);
+	if (!parser)
+		return err;
+
+	ret = mtd_part_do_parse(parser, master, pparts, data);
+	if (ret > 0)
+		return 0;
+	mtd_part_parser_put(parser);
+	if (ret < 0 && !err)
+		err = ret;
+
 	return err;
 }
 
diff --git a/include/linux/mtd/partitions.h b/include/linux/mtd/partitions.h
index 2787e76c030f..073e1d8d5d17 100644
--- a/include/linux/mtd/partitions.h
+++ b/include/linux/mtd/partitions.h
@@ -77,6 +77,7 @@ struct mtd_part_parser {
 	struct list_head list;
 	struct module *owner;
 	const char *name;
+	const struct of_device_id *of_match_table;
 	int (*parse_fn)(struct mtd_info *, const struct mtd_partition **,
 			struct mtd_part_parser_data *);
 	void (*cleanup)(const struct mtd_partition *pparts, int nr_parts);
-- 
2.11.0