kernel: mtd: parsers: add nvmem support to cmdlinepart

Assuming cmdlinepart is only one level deep partition scheme and that
static partition are also defined in DTS, we can assign an of_node for
partition declared from bootargs.

The cmdlinepart parser is the first parser checked and if it does find
some partition declared in the bootargs, every other parser is ignored.
This means that the fixed-partition parser is ignored and an of_node for
the mtd is never assigned.
Fix this by searching a defined of_node using a similar fixed_partition
parsing logig, check if a partition is present with the same label, check
that it has the same offset and size and finally assign an of_node to the
mtd. The NVMEM can now find the of_node for the mtd and correctly works.

Fixes: abc17bf306ac ("ath79: convert mtd-mac-address to nvmem implementation")
Tested-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>

1 files changed, 120 insertions, 0 deletions

diff --git a/target/linux/generic/hack-5.10/421-drivers-mtd-parsers-add-nvmem-support-to-cmdlinepart.patch b/target/linux/generic/hack-5.10/421-drivers-mtd-parsers-add-nvmem-support-to-cmdlinepart.patch
new file mode 100644
index 0000000000..965a331a19
--- /dev/null
+++ b/target/linux/generic/hack-5.10/421-drivers-mtd-parsers-add-nvmem-support-to-cmdlinepart.patch
@@ -0,0 +1,120 @@
+From 6fa9e3678eb002246df1280322b6a024853950a5 Mon Sep 17 00:00:00 2001
+From: Ansuel Smith <ansuelsmth@gmail.com>
+Date: Mon, 11 Oct 2021 00:53:14 +0200
+Subject: [PATCH] drivers: mtd: parsers: add nvmem support to cmdlinepart
+
+Assuming cmdlinepart is only one level deep partition scheme and that
+static partition are also defined in DTS, we can assign an of_node for
+partition declared from bootargs. cmdlinepart have priority than
+fiexed-partition parser so in this specific case the parser doesn't
+assign an of_node. Fix this by searching a defined of_node using a
+similar fixed_partition parser and if a partition is found with the same
+label, check that it has the same offset and size and return the DT
+of_node to correctly use NVMEM cells.
+
+Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
+---
+ drivers/mtd/parsers/cmdlinepart.c | 71 +++++++++++++++++++++++++++++++
+ 1 file changed, 71 insertions(+)
+
+--- a/drivers/mtd/parsers/cmdlinepart.c
++++ b/drivers/mtd/parsers/cmdlinepart.c
+@@ -43,6 +43,7 @@
+ #include <linux/mtd/partitions.h>
+ #include <linux/module.h>
+ #include <linux/err.h>
++#include <linux/of.h>
+ 
+ /* debug macro */
+ #if 0
+@@ -323,6 +324,68 @@ static int mtdpart_setup_real(char *s)
+ 	return 0;
+ }
+ 
++static int search_fixed_partition(struct mtd_info *master,
++				  struct mtd_partition *target_part,
++				  struct mtd_partition *fixed_part)
++{
++	struct device_node *mtd_node;
++	struct device_node *ofpart_node;
++	struct device_node *pp;
++	struct mtd_partition part;
++	const char *partname;
++
++	mtd_node = mtd_get_of_node(master);
++	if (!mtd_node)
++		return -EINVAL;
++
++	ofpart_node = of_get_child_by_name(mtd_node, "partitions");
++
++	for_each_child_of_node(ofpart_node,  pp) {
++		const __be32 *reg;
++		int len;
++		int a_cells, s_cells;
++
++		reg = of_get_property(pp, "reg", &len);
++		if (!reg) {
++			pr_debug("%s: ofpart partition %pOF (%pOF) missing reg property.\n",
++				 master->name, pp,
++				 mtd_node);
++			continue;
++		}
++
++		a_cells = of_n_addr_cells(pp);
++		s_cells = of_n_size_cells(pp);
++		if (len / 4 != a_cells + s_cells) {
++			pr_debug("%s: ofpart partition %pOF (%pOF) error parsing reg property.\n",
++				 master->name, pp,
++				 mtd_node);
++			continue;
++		}
++
++		part.offset = of_read_number(reg, a_cells);
++		part.size = of_read_number(reg + a_cells, s_cells);
++		part.of_node = pp;
++
++		partname = of_get_property(pp, "label", &len);
++		if (!partname)
++			partname = of_get_property(pp, "name", &len);
++		part.name = partname;
++
++		if (!strncmp(target_part->name, part.name, len)) {
++			if (part.offset != target_part->offset)
++				return -EINVAL;
++
++			if (part.size != target_part->size)
++				return -EINVAL;
++
++			memcpy(fixed_part, &part, sizeof(struct mtd_partition));
++			return 0;
++		}
++	}
++
++	return -EINVAL;
++}
++
+ /*
+  * Main function to be called from the MTD mapping driver/device to
+  * obtain the partitioning information. At this point the command line
+@@ -338,6 +401,7 @@ static int parse_cmdline_partitions(stru
+ 	int i, err;
+ 	struct cmdline_mtd_partition *part;
+ 	const char *mtd_id = master->name;
++	struct mtd_partition fixed_part;
+ 
+ 	/* parse command line */
+ 	if (!cmdline_parsed) {
+@@ -382,6 +446,13 @@ static int parse_cmdline_partitions(stru
+ 				sizeof(*part->parts) * (part->num_parts - i));
+ 			i--;
+ 		}
++
++		err = search_fixed_partition(master, &part->parts[i], &fixed_part);
++		if (!err) {
++			part->parts[i].of_node = fixed_part.of_node;
++			pr_info("Found partition defined in DT for %s. Assigning OF node to support nvmem.",
++				part->parts[i].name);
++		}
+ 	}
+ 
+ 	*pparts = kmemdup(part->parts, sizeof(*part->parts) * part->num_parts,