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authorDan Ehrenberg <dehrenberg@chromium.org>2015-04-03 00:15:10 +0200
committerBrian Norris <computersforpeace@gmail.com>2015-04-06 02:44:01 +0200
commit727dc612c46b8f3858537ea23805b3e897cf127e (patch)
tree5bcda420d5f0071fc8d8c8c02dc68166256323e7 /drivers/mtd/mtdpart.c
parentmtd: ts5500_flash: Fix typo in MODULE_DESCRIPTION in ts5500_flash.c (diff)
downloadlinux-727dc612c46b8f3858537ea23805b3e897cf127e.tar.xz
linux-727dc612c46b8f3858537ea23805b3e897cf127e.zip
mtd: part: Create the master device node when partitioned
For many use cases, it helps to have a device node for the entire MTD device as well as device nodes for the individual partitions. For example, this allows querying the entire device's properties. A common idiom is to create an additional partition which spans over the whole device. This patch makes a config option, CONFIG_MTD_PARTITIONED_MASTER, which makes the master partition present even when the device is partitioned. This isn't turned on by default since it presents a backwards-incompatible device numbering. The patch also makes the parent of a partition device be the master, if the config flag is set, now that the master is a full device. Signed-off-by: Dan Ehrenberg <dehrenberg@chromium.org> Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Diffstat (limited to 'drivers/mtd/mtdpart.c')
-rw-r--r--drivers/mtd/mtdpart.c18
1 files changed, 13 insertions, 5 deletions
diff --git a/drivers/mtd/mtdpart.c b/drivers/mtd/mtdpart.c
index e779de315ade..a19ec5a4e409 100644
--- a/drivers/mtd/mtdpart.c
+++ b/drivers/mtd/mtdpart.c
@@ -30,6 +30,7 @@
#include <linux/mtd/mtd.h>
#include <linux/mtd/partitions.h>
#include <linux/err.h>
+#include <linux/kconfig.h>
#include "mtdcore.h"
@@ -379,10 +380,17 @@ static struct mtd_part *allocate_partition(struct mtd_info *master,
slave->mtd.name = name;
slave->mtd.owner = master->owner;
- /* NOTE: we don't arrange MTDs as a tree; it'd be error-prone
- * to have the same data be in two different partitions.
+ /* NOTE: Historically, we didn't arrange MTDs as a tree out of
+ * concern for showing the same data in multiple partitions.
+ * However, it is very useful to have the master node present,
+ * so the MTD_PARTITIONED_MASTER option allows that. The master
+ * will have device nodes etc only if this is set, so make the
+ * parent conditional on that option. Note, this is a way to
+ * distinguish between the master and the partition in sysfs.
*/
- slave->mtd.dev.parent = master->dev.parent;
+ slave->mtd.dev.parent = IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER) ?
+ &master->dev :
+ master->dev.parent;
slave->mtd._read = part_read;
slave->mtd._write = part_write;
@@ -631,8 +639,8 @@ EXPORT_SYMBOL_GPL(mtd_del_partition);
* and registers slave MTD objects which are bound to the master according to
* the partition definitions.
*
- * We don't register the master, or expect the caller to have done so,
- * for reasons of data integrity.
+ * For historical reasons, this function's caller only registers the master
+ * if the MTD_PARTITIONED_MASTER config option is set.
*/
int add_mtd_partitions(struct mtd_info *master,