Revert "mtd: core: always create master device"

The idea behind this patch was to always let a "master" mtd device
available to anchor runtime PM. Historically, there was no mtd device
representing the whole storage as soon as partitions were coming into
play. The introduction of CONFIG_MTD_PARTITIONED_MASTER allowed to keep
this "master" device, but was not enabled by default to avoid breaking
existing users (otherwise the mtd device numbering would be totally
messed up with an off by 1, at least).

The approach of adding an mtd_master class on top of partitioned mtd
devices is breaking the mtd core in many creative ways, so better think
again this approach and revert the faulty changes for now.

This reverts commit 0aa7b390fc40a871267a2328bbbefca8b37ad307.

Fixes: 0aa7b390fc40 ("mtd: core: always create master device")
Tested-by: Guenter Roeck <[e-mail]>
Acked-by: Guenter Roeck <[e-mail]>
Signed-off-by: Miquel Raynal <[e-mail]>

drivers/mtd/mtdchar.c

···
 		/* Sanitize user input */
 		p.devname[BLKPG_DEVNAMELTH - 1] = '\0';
 
-		return mtd_add_partition(mtd, p.devname, p.start, p.length, NULL);
+		return mtd_add_partition(mtd, p.devname, p.start, p.length);
 
 	case BLKPG_DEL_PARTITION:
 

drivers/mtd/mtdcore.c

···
 	.pm = MTD_CLS_PM_OPS,
 };
 
-static struct class mtd_master_class = {
-	.name = "mtd_master",
-	.pm = MTD_CLS_PM_OPS,
-};
-
 static DEFINE_IDR(mtd_idr);
-static DEFINE_IDR(mtd_master_idr);
 
 /* These are exported solely for the purpose of mtd_blkdevs.c. You
    should not use them for _anything_ else */
···
 
 static LIST_HEAD(mtd_notifiers);
 
-#define MTD_MASTER_DEVS 255
+
 #define MTD_DEVT(index) MKDEV(MTD_CHAR_MAJOR, (index)*2)
-static dev_t mtd_master_devt;
 
 /* REVISIT once MTD uses the driver model better, whoever allocates
  * the mtd_info will probably want to use the release() hook...
···
 
 	/* remove /dev/mtdXro node */
 	device_destroy(&mtd_class, index + 1);
-}
-
-static void mtd_master_release(struct device *dev)
-{
-	struct mtd_info *mtd = dev_get_drvdata(dev);
-
-	idr_remove(&mtd_master_idr, mtd->index);
-	of_node_put(mtd_get_of_node(mtd));
-
-	if (mtd_is_partition(mtd))
-		release_mtd_partition(mtd);
 }
 
 static void mtd_device_release(struct kref *kref)
···
 	.name		= "mtd",
 	.groups		= mtd_groups,
 	.release	= mtd_release,
-};
-
-static const struct device_type mtd_master_devtype = {
-	.name		= "mtd_master",
-	.release	= mtd_master_release,
 };
 
 static bool mtd_expert_analysis_mode;
···
 /**
  *	add_mtd_device - register an MTD device
  *	@mtd: pointer to new MTD device info structure
- *	@partitioned: create partitioned device
  *
  *	Add a device to the list of MTD devices present in the system, and
  *	notify each currently active MTD 'user' of its arrival. Returns
  *	zero on success or non-zero on failure.
  */
-int add_mtd_device(struct mtd_info *mtd, bool partitioned)
+
+int add_mtd_device(struct mtd_info *mtd)
 {
 	struct device_node *np = mtd_get_of_node(mtd);
 	struct mtd_info *master = mtd_get_master(mtd);
···
 	ofidx = -1;
 	if (np)
 		ofidx = of_alias_get_id(np, "mtd");
-	if (partitioned) {
-		if (ofidx >= 0)
-			i = idr_alloc(&mtd_idr, mtd, ofidx, ofidx + 1, GFP_KERNEL);
-		else
-			i = idr_alloc(&mtd_idr, mtd, 0, 0, GFP_KERNEL);
-	} else {
-		if (ofidx >= 0)
-			i = idr_alloc(&mtd_master_idr, mtd, ofidx, ofidx + 1, GFP_KERNEL);
-		else
-			i = idr_alloc(&mtd_master_idr, mtd, 0, 0, GFP_KERNEL);
-	}
+	if (ofidx >= 0)
+		i = idr_alloc(&mtd_idr, mtd, ofidx, ofidx + 1, GFP_KERNEL);
+	else
+		i = idr_alloc(&mtd_idr, mtd, 0, 0, GFP_KERNEL);
 	if (i < 0) {
 		error = i;
 		goto fail_locked;
···
 	/* Caller should have set dev.parent to match the
 	 * physical device, if appropriate.
 	 */
-	if (partitioned) {
-		mtd->dev.type = &mtd_devtype;
-		mtd->dev.class = &mtd_class;
-		mtd->dev.devt = MTD_DEVT(i);
-		dev_set_name(&mtd->dev, "mtd%d", i);
-		error = dev_set_name(&mtd->dev, "mtd%d", i);
-	} else {
-		mtd->dev.type = &mtd_master_devtype;
-		mtd->dev.class = &mtd_master_class;
-		mtd->dev.devt = MKDEV(MAJOR(mtd_master_devt), i);
-		error = dev_set_name(&mtd->dev, "mtd_master%d", i);
-	}
+	mtd->dev.type = &mtd_devtype;
+	mtd->dev.class = &mtd_class;
+	mtd->dev.devt = MTD_DEVT(i);
+	error = dev_set_name(&mtd->dev, "mtd%d", i);
 	if (error)
 		goto fail_devname;
 	dev_set_drvdata(&mtd->dev, mtd);
···
 	of_node_get(mtd_get_of_node(mtd));
 	error = device_register(&mtd->dev);
 	if (error) {
-		pr_err("mtd: %s device_register fail %d\n", mtd->name, error);
 		put_device(&mtd->dev);
 		goto fail_added;
 	}
···
 
 	mtd_debugfs_populate(mtd);
 
-	if (partitioned) {
-		device_create(&mtd_class, mtd->dev.parent, MTD_DEVT(i) + 1, NULL,
-			      "mtd%dro", i);
-	}
+	device_create(&mtd_class, mtd->dev.parent, MTD_DEVT(i) + 1, NULL,
+		      "mtd%dro", i);
 
-	pr_debug("mtd: Giving out %spartitioned device %d to %s\n",
-		 partitioned ? "" : "un-", i, mtd->name);
+	pr_debug("mtd: Giving out device %d to %s\n", i, mtd->name);
 	/* No need to get a refcount on the module containing
 	   the notifier, since we hold the mtd_table_mutex */
 	list_for_each_entry(not, &mtd_notifiers, list)
···
 
 	mutex_unlock(&mtd_table_mutex);
 
-	if (partitioned) {
-		if (of_property_read_bool(mtd_get_of_node(mtd), "linux,rootfs")) {
-			if (IS_BUILTIN(CONFIG_MTD)) {
-				pr_info("mtd: setting mtd%d (%s) as root device\n",
-					mtd->index, mtd->name);
-				ROOT_DEV = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
-			} else {
-				pr_warn("mtd: can't set mtd%d (%s) as root device - mtd must be builtin\n",
-					mtd->index, mtd->name);
-			}
+	if (of_property_read_bool(mtd_get_of_node(mtd), "linux,rootfs")) {
+		if (IS_BUILTIN(CONFIG_MTD)) {
+			pr_info("mtd: setting mtd%d (%s) as root device\n", mtd->index, mtd->name);
+			ROOT_DEV = MKDEV(MTD_BLOCK_MAJOR, mtd->index);
+		} else {
+			pr_warn("mtd: can't set mtd%d (%s) as root device - mtd must be builtin\n",
+				mtd->index, mtd->name);
 		}
 	}
 
···
 fail_added:
 	of_node_put(mtd_get_of_node(mtd));
 fail_devname:
-	if (partitioned)
-		idr_remove(&mtd_idr, i);
-	else
-		idr_remove(&mtd_master_idr, i);
+	idr_remove(&mtd_idr, i);
 fail_locked:
 	mutex_unlock(&mtd_table_mutex);
 	return error;
···
 
 int del_mtd_device(struct mtd_info *mtd)
 {
-	struct mtd_notifier *not;
-	struct idr *idr;
 	int ret;
+	struct mtd_notifier *not;
 
 	mutex_lock(&mtd_table_mutex);
 
-	idr = mtd->dev.class == &mtd_class ? &mtd_idr : &mtd_master_idr;
-	if (idr_find(idr, mtd->index) != mtd) {
+	if (idr_find(&mtd_idr, mtd->index) != mtd) {
 		ret = -ENODEV;
 		goto out_error;
 	}
···
 			      const struct mtd_partition *parts,
 			      int nr_parts)
 {
-	struct mtd_info *parent;
 	int ret, err;
 
 	mtd_set_dev_defaults(mtd);
···
 	if (ret)
 		goto out;
 
-	ret = add_mtd_device(mtd, false);
-	if (ret)
-		goto out;
-
 	if (IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER)) {
-		ret = mtd_add_partition(mtd, mtd->name, 0, MTDPART_SIZ_FULL, &parent);
+		ret = add_mtd_device(mtd);
 		if (ret)
 			goto out;
-
-	} else {
-		parent = mtd;
 	}
 
 	/* Prefer parsed partitions over driver-provided fallback */
-	ret = parse_mtd_partitions(parent, types, parser_data);
+	ret = parse_mtd_partitions(mtd, types, parser_data);
 	if (ret == -EPROBE_DEFER)
 		goto out;
 
 	if (ret > 0)
 		ret = 0;
 	else if (nr_parts)
-		ret = add_mtd_partitions(parent, parts, nr_parts);
-	else if (!IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER))
-		ret = mtd_add_partition(parent, mtd->name, 0, MTDPART_SIZ_FULL, NULL);
+		ret = add_mtd_partitions(mtd, parts, nr_parts);
+	else if (!device_is_registered(&mtd->dev))
+		ret = add_mtd_device(mtd);
+	else
+		ret = 0;
 
 	if (ret)
 		goto out;
···
 		register_reboot_notifier(&mtd->reboot_notifier);
 	}
 
-	return 0;
 out:
-	nvmem_unregister(mtd->otp_user_nvmem);
-	nvmem_unregister(mtd->otp_factory_nvmem);
+	if (ret) {
+		nvmem_unregister(mtd->otp_user_nvmem);
+		nvmem_unregister(mtd->otp_factory_nvmem);
+	}
 
-	del_mtd_partitions(mtd);
-
-	if (device_is_registered(&mtd->dev)) {
+	if (ret && device_is_registered(&mtd->dev)) {
 		err = del_mtd_device(mtd);
 		if (err)
 			pr_err("Error when deleting MTD device (%d)\n", err);
···
 		mtd = mtd->parent;
 	}
 
-	kref_get(&master->refcnt);
+	if (IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER))
+		kref_get(&master->refcnt);
 
 	return 0;
 }
···
 		mtd = parent;
 	}
 
-	kref_put(&master->refcnt, mtd_device_release);
+	if (IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER))
+		kref_put(&master->refcnt, mtd_device_release);
 
 	module_put(master->owner);
 
···
 	if (ret)
 		goto err_reg;
 
-	ret = class_register(&mtd_master_class);
-	if (ret)
-		goto err_reg2;
-
-	ret = alloc_chrdev_region(&mtd_master_devt, 0, MTD_MASTER_DEVS, "mtd_master");
-	if (ret < 0) {
-		pr_err("unable to allocate char dev region\n");
-		goto err_chrdev;
-	}
-
 	mtd_bdi = mtd_bdi_init("mtd");
 	if (IS_ERR(mtd_bdi)) {
 		ret = PTR_ERR(mtd_bdi);
···
 	bdi_unregister(mtd_bdi);
 	bdi_put(mtd_bdi);
 err_bdi:
-	unregister_chrdev_region(mtd_master_devt, MTD_MASTER_DEVS);
-err_chrdev:
-	class_unregister(&mtd_master_class);
-err_reg2:
 	class_unregister(&mtd_class);
 err_reg:
 	pr_err("Error registering mtd class or bdi: %d\n", ret);
···
 	if (proc_mtd)
 		remove_proc_entry("mtd", NULL);
 	class_unregister(&mtd_class);
-	class_unregister(&mtd_master_class);
-	unregister_chrdev_region(mtd_master_devt, MTD_MASTER_DEVS);
 	bdi_unregister(mtd_bdi);
 	bdi_put(mtd_bdi);
 	idr_destroy(&mtd_idr);
-	idr_destroy(&mtd_master_idr);
 }
 
 module_init(init_mtd);

drivers/mtd/mtdcore.h

···
 extern struct backing_dev_info *mtd_bdi;
 
 struct mtd_info *__mtd_next_device(int i);
-int __must_check add_mtd_device(struct mtd_info *mtd, bool partitioned);
+int __must_check add_mtd_device(struct mtd_info *mtd);
 int del_mtd_device(struct mtd_info *mtd);
 int add_mtd_partitions(struct mtd_info *, const struct mtd_partition *, int);
 int del_mtd_partitions(struct mtd_info *);

drivers/mtd/mtdpart.c

···
 	 * parent conditional on that option. Note, this is a way to
 	 * distinguish between the parent and its partitions in sysfs.
 	 */
-	child->dev.parent = &parent->dev;
+	child->dev.parent = IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER) || mtd_is_partition(parent) ?
+			    &parent->dev : parent->dev.parent;
 	child->dev.of_node = part->of_node;
 	child->parent = parent;
 	child->part.offset = part->offset;
···
 }
 
 int mtd_add_partition(struct mtd_info *parent, const char *name,
-		      long long offset, long long length, struct mtd_info **out)
+		      long long offset, long long length)
 {
 	struct mtd_info *master = mtd_get_master(parent);
 	u64 parent_size = mtd_is_partition(parent) ?
···
 	list_add_tail(&child->part.node, &parent->partitions);
 	mutex_unlock(&master->master.partitions_lock);
 
-	ret = add_mtd_device(child, true);
+	ret = add_mtd_device(child);
 	if (ret)
 		goto err_remove_part;
 
 	mtd_add_partition_attrs(child);
-
-	if (out)
-		*out = child;
 
 	return 0;
 
···
 		list_add_tail(&child->part.node, &parent->partitions);
 		mutex_unlock(&master->master.partitions_lock);
 
-		ret = add_mtd_device(child, true);
+		ret = add_mtd_device(child);
 		if (ret) {
 			mutex_lock(&master->master.partitions_lock);
 			list_del(&child->part.node);
···
 	int ret, err = 0;
 
 	dev = &master->dev;
+	/* Use parent device (controller) if the top level MTD is not registered */
+	if (!IS_ENABLED(CONFIG_MTD_PARTITIONED_MASTER) && !mtd_is_partition(master))
+		dev = master->dev.parent;
 
 	np = mtd_get_of_node(master);
 	if (mtd_is_partition(master))
···
 		if (ret < 0 && !err)
 			err = ret;
 	}
-
 	return err;
 }
 

include/linux/mtd/partitions.h

···
 		      deregister_mtd_parser)
 
 int mtd_add_partition(struct mtd_info *master, const char *name,
-		      long long offset, long long length, struct mtd_info **part);
+		      long long offset, long long length);
 int mtd_del_partition(struct mtd_info *master, int partno);
 uint64_t mtd_get_device_size(const struct mtd_info *mtd);