mtd: introduce mtd_device_(un)register()

To prepare for the removal of add_mtd_device and add_mtd_partitions(),
introduce mtd_device_register().  This will create partitions if they
are supplied or register the whole device if there are no partitions.

Once all drivers are converted to use mtd_device_register(),
add_mtd_device() and add_mtd_partitions() will be made internal only.

v2: move kerneldoc to implementation file and fixup some kerneldoc
warnings.

Artem: tweak comments: remove junk tabs, use dots consistently.
Signed-off-by: NJamie Iles <jamie@jamieiles.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/mtdcore.c

@@ -38,6 +38,7 @@
 #include <linux/gfp.h>
 
 #include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
 
 #include "mtdcore.h"
 /*
@@ -427,6 +428,50 @@ int del_mtd_device (struct mtd_info *mtd)
 	return ret;
 }
 
+/**
+ * mtd_device_register - register an MTD device.
+ *
+ * @master: the MTD device to register
+ * @parts: the partitions to register - only valid if nr_parts > 0
+ * @nr_parts: the number of partitions in parts.  If zero then the full MTD
+ *            device is registered
+ *
+ * Register an MTD device with the system and optionally, a number of
+ * partitions.  If nr_parts is 0 then the whole device is registered, otherwise
+ * only the partitions are registered.  To register both the full device *and*
+ * the partitions, call mtd_device_register() twice, once with nr_parts == 0
+ * and once equal to the number of partitions.
+ */
+int mtd_device_register(struct mtd_info *master,
+			const struct mtd_partition *parts,
+			int nr_parts)
+{
+	return parts ? add_mtd_partitions(master, parts, nr_parts) :
+		add_mtd_device(master);
+}
+EXPORT_SYMBOL_GPL(mtd_device_register);
+
+/**
+ * mtd_device_unregister - unregister an existing MTD device.
+ *
+ * @master: the MTD device to unregister.  This will unregister both the master
+ *          and any partitions if registered.
+ */
+int mtd_device_unregister(struct mtd_info *master)
+{
+	int err;
+
+	err = del_mtd_partitions(master);
+	if (err)
+		return err;
+
+	if (!device_is_registered(&master->dev))
+		return 0;
+
+	return del_mtd_device(master);
+}
+EXPORT_SYMBOL_GPL(mtd_device_unregister);
+
 /**
  *	register_mtd_user - register a 'user' of MTD devices.
  *	@new: pointer to notifier info structure

include/linux/mtd/mtd.h

@@ -325,6 +325,12 @@ static inline uint32_t mtd_mod_by_ws(uint64_t sz, struct mtd_info *mtd)
 extern int add_mtd_device(struct mtd_info *mtd);
 extern int del_mtd_device (struct mtd_info *mtd);
 
+struct mtd_partition;
+
+extern int mtd_device_register(struct mtd_info *master,
+			       const struct mtd_partition *parts,
+			       int nr_parts);
+extern int mtd_device_unregister(struct mtd_info *master);
 extern struct mtd_info *get_mtd_device(struct mtd_info *mtd, int num);
 extern int __get_mtd_device(struct mtd_info *mtd);
 extern void __put_mtd_device(struct mtd_info *mtd);

include/linux/mtd/partitions.h

@@ -16,7 +16,7 @@
  * Partition definition structure:
  *
  * An array of struct partition is passed along with a MTD object to
- * add_mtd_partitions() to create them.
+ * mtd_device_register() to create them.
  *
  * For each partition, these fields are available:
  * name: string that will be used to label the partition's MTD device.