[PATCH V2] mtd: call of_platform_populate() for MTD partitions

Rafał Miłecki
2022-05-04T19:45:51Z

From: Rafał Miłecki <rafal@milecki.pl>

Until this change MTD subsystem supported handling partitions only with
MTD partitions parsers. That's a specific / limited API designed around
partitions.

Some MTD partitions may however require different handling. They may
contain specific data that needs to be parsed and somehow extracted. For
that purpose MTD subsystem should allow binding of standard platform
drivers.

An example can be U-Boot (sub)partition with environment variables.
There exist a "u-boot,env" DT binding for MTD (sub)partition that
requires an NVMEM driver.

Ref: 5db1c2dbc04c ("dt-bindings: nvmem: add U-Boot environment variables binding")
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
V2: Fix case for # CONFIG_MTD_PARTITIONED_MASTER is not set
master->dev can't be used blindly as it may point to unregistered
device and cause WARNINGs
---
drivers/mtd/mtdpart.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index 357661b62c94..4971fa69d076 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -17,6 +17,7 @@
#include <linux/mtd/partitions.h>
#include <linux/err.h>
#include <linux/of.h>
+#include <linux/of_platform.h>

#include "mtdcore.h"

@@ -577,10 +578,16 @@ static int mtd_part_of_parse(struct mtd_info *master,
struct mtd_part_parser *parser;
struct device_node *np;
struct property *prop;
+ struct device *dev;
const char *compat;
const char *fixed = "fixed-partitions";
int ret, err = 0;

+ if (mtd_is_partition(master) || IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER))
+ dev = &master->dev;
+ else
+ dev = master->dev.parent;
+
np = mtd_get_of_node(master);
if (mtd_is_partition(master))
of_node_get(np);
@@ -593,6 +600,7 @@ static int mtd_part_of_parse(struct mtd_info *master,
continue;
ret = mtd_part_do_parse(parser, master, pparts, NULL);
if (ret > 0) {
+ of_platform_populate(np, NULL, NULL, dev);
of_node_put(np);
return ret;
}
@@ -600,6 +608,7 @@ static int mtd_part_of_parse(struct mtd_info *master,
if (ret < 0 && !err)
err = ret;
}
+ of_platform_populate(np, NULL, NULL, dev);
of_node_put(np);

/*
--
2.34.1