Using an MTD device (resp. partition) name in mtdparts is simple and
straightforward. However, for a long time already, another name was
given in mtdparts to indicate a device (resp. partition) so the
"mtdids" environment variable was created to do the match.
Let's create a function that, from an MTD device (resp. partition)
name, search for the equivalent name in the "mtdparts" environment
variable thanks to the "mtdids" string.
Signed-off-by: Miquel Raynal <miquel.ray...@bootlin.com>
---
drivers/mtd/mtdpart.c | 62 ++++++++++++++++++++++++++++++++++
include/linux/mtd/partitions.h | 2 ++
2 files changed, 64 insertions(+)
diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index d9708da2ae..096351e48b 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -263,6 +263,68 @@ int mtd_parse_partitions(struct mtd_info *parent, const
char **_mtdparts,
return 0;
}
+/**
+ * mtd_search_alternate_name - Search an alternate name for @mtdname thanks to
+ * the mtdids legacy environment variable.
+ *
+ * The mtdids string is a list of comma-separated 'dev_id=mtd_id' tupples.
+ * Check if one of the mtd_id matches mtdname, in this case save dev_id in
+ * altname.
+ *
+ * @mtdname: Current MTD device name
+ * @altname: Alternate name to return
+ * @max_len: Length of the alternate name buffer
+ *
+ * @return 0 on success, an error otherwise.
+ */
+int mtd_search_alternate_name(const char *mtdname, char *altname,
+ unsigned int max_len)
+{
+ const char *mtdids, *equal, *comma, *dev_id, *mtd_id;
+ int dev_id_len, mtd_id_len;
+
+ mtdids = env_get("mtdids");
+ if (!mtdids)
+ return -EINVAL;
+
+ do {
+ /* Find the '=' sign */
+ dev_id = mtdids;
+ equal = strchr(dev_id, '=');
+ if (!equal)
+ break;
+
+ dev_id_len = equal - mtdids;
+ mtd_id = equal + 1;
+
+ /* Find the end of the tupple */
+ comma = strchr(mtdids, ',');
+ if (comma)
+ mtd_id_len = comma - equal;
+ else
+ mtd_id_len = &mtdids[strlen(mtdids)] - equal;
+
+ if (!dev_id_len || !mtd_id_len)
+ return -EINVAL;
+
+ if (dev_id_len + 1 > max_len)
+ continue;
+
+ /* Compare the name we search with the current mtd_id */
+ if (!strncmp(mtdname, mtd_id, mtd_id_len)) {
+ strncpy(altname, dev_id, dev_id_len);
+ altname[dev_id_len] = 0;
+
+ return 0;
+ }
+
+ /* Go to the next tupple */
+ mtdids = comma + 1;
+ } while (comma);
+
+ return -EINVAL;
+}
+
/*
* MTD methods which simply translate the effective address and pass through
* to the _real_ device.
diff --git a/include/linux/mtd/partitions.h b/include/linux/mtd/partitions.h
index ed4ece5e13..082a4966ea 100644
--- a/include/linux/mtd/partitions.h
+++ b/include/linux/mtd/partitions.h
@@ -88,5 +88,7 @@ int mtd_del_partition(struct mtd_info *master, int partno);
uint64_t mtd_get_device_size(const struct mtd_info *mtd);
int mtd_parse_partitions(struct mtd_info *parent, const char **_mtdparts,
struct mtd_partition **_parts, int *_nb_parts);
+int mtd_search_alternate_name(const char *mtdname, char *altname,
+ unsigned int max_len);
#endif
--
2.17.1
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