9 files changed, 497 insertions, 145 deletions

diff --git a/drivers/mtd/ubi/Kconfig b/drivers/mtd/ubi/Kconfig
index 7499a54012..e28a3af83c 100644
--- a/drivers/mtd/ubi/Kconfig
+++ b/drivers/mtd/ubi/Kconfig
@@ -113,4 +113,17 @@ config MTD_UBI_FAULT_INJECTION
 	   testing purposes.
 
 	   If in doubt, say "N".
+
+config MTD_UBI_NVMEM
+	tristate "UBI virtual NVMEM"
+	default n
+	depends on NVMEM
+	help
+	   This option enabled an additional driver exposing UBI volumes as NVMEM
+	   providers, intended for platforms where UBI is part of the firmware
+	   specification and used to store also e.g. MAC addresses or board-
+	   specific Wi-Fi calibration data.
+
+	   If in doubt, say "N".
+
 endif # MTD_UBI
diff --git a/drivers/mtd/ubi/Makefile b/drivers/mtd/ubi/Makefile
index 543673605c..4b51aaf00d 100644
--- a/drivers/mtd/ubi/Makefile
+++ b/drivers/mtd/ubi/Makefile
@@ -7,3 +7,4 @@ ubi-$(CONFIG_MTD_UBI_FASTMAP) += fastmap.o
 ubi-$(CONFIG_MTD_UBI_BLOCK) += block.o
 
 obj-$(CONFIG_MTD_UBI_GLUEBI) += gluebi.o
+obj-$(CONFIG_MTD_UBI_NVMEM) += nvmem.o
diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
index 654bd7372c..f82e3423ac 100644
--- a/drivers/mtd/ubi/block.c
+++ b/drivers/mtd/ubi/block.c
@@ -65,10 +65,10 @@ struct ubiblock_pdu {
 };
 
 /* Numbers of elements set in the @ubiblock_param array */
-static int ubiblock_devs __initdata;
+static int ubiblock_devs;
 
 /* MTD devices specification parameters */
-static struct ubiblock_param ubiblock_param[UBIBLOCK_MAX_DEVICES] __initdata;
+static struct ubiblock_param ubiblock_param[UBIBLOCK_MAX_DEVICES];
 
 struct ubiblock {
 	struct ubi_volume_desc *desc;
@@ -348,6 +348,9 @@ static int calc_disk_capacity(struct ubi_volume_info *vi, u64 *disk_capacity)
 
 int ubiblock_create(struct ubi_volume_info *vi)
 {
+	struct queue_limits lim = {
+		.max_segments		= UBI_MAX_SG_COUNT,
+	};
 	struct ubiblock *dev;
 	struct gendisk *gd;
 	u64 disk_capacity;
@@ -393,7 +396,7 @@ int ubiblock_create(struct ubi_volume_info *vi)
 
 
 	/* Initialize the gendisk of this ubiblock device */
-	gd = blk_mq_alloc_disk(&dev->tag_set, dev);
+	gd = blk_mq_alloc_disk(&dev->tag_set, &lim, dev);
 	if (IS_ERR(gd)) {
 		ret = PTR_ERR(gd);
 		goto out_free_tags;
@@ -416,7 +419,6 @@ int ubiblock_create(struct ubi_volume_info *vi)
 	dev->gd = gd;
 
 	dev->rq = gd->queue;
-	blk_queue_max_segments(dev->rq, UBI_MAX_SG_COUNT);
 
 	list_add_tail(&dev->list, &ubiblock_devices);
 
@@ -534,6 +536,70 @@ static int ubiblock_resize(struct ubi_volume_info *vi)
 	return 0;
 }
 
+static bool
+match_volume_desc(struct ubi_volume_info *vi, const char *name, int ubi_num, int vol_id)
+{
+	int err, len, cur_ubi_num, cur_vol_id;
+
+	if (ubi_num == -1) {
+		/* No ubi num, name must be a vol device path */
+		err = ubi_get_num_by_path(name, &cur_ubi_num, &cur_vol_id);
+		if (err || vi->ubi_num != cur_ubi_num || vi->vol_id != cur_vol_id)
+			return false;
+
+		return true;
+	}
+
+	if (vol_id == -1) {
+		/* Got ubi_num, but no vol_id, name must be volume name */
+		if (vi->ubi_num != ubi_num)
+			return false;
+
+		len = strnlen(name, UBI_VOL_NAME_MAX + 1);
+		if (len < 1 || vi->name_len != len)
+			return false;
+
+		if (strcmp(name, vi->name))
+			return false;
+
+		return true;
+	}
+
+	if (vi->ubi_num != ubi_num)
+		return false;
+
+	if (vi->vol_id != vol_id)
+		return false;
+
+	return true;
+}
+
+static void
+ubiblock_create_from_param(struct ubi_volume_info *vi)
+{
+	int i, ret = 0;
+	struct ubiblock_param *p;
+
+	/*
+	 * Iterate over ubiblock cmdline parameters. If a parameter matches the
+	 * newly added volume create the ubiblock device for it.
+	 */
+	for (i = 0; i < ubiblock_devs; i++) {
+		p = &ubiblock_param[i];
+
+		if (!match_volume_desc(vi, p->name, p->ubi_num, p->vol_id))
+			continue;
+
+		ret = ubiblock_create(vi);
+		if (ret) {
+			pr_err(
+			       "UBI: block: can't add '%s' volume on ubi%d_%d, err=%d\n",
+			       vi->name, p->ubi_num, p->vol_id, ret);
+		}
+		break;
+	}
+}
+
 static int ubiblock_notify(struct notifier_block *nb,
 			 unsigned long notification_type, void *ns_ptr)
 {
@@ -541,10 +607,7 @@ static int ubiblock_notify(struct notifier_block *nb,
 
 	switch (notification_type) {
 	case UBI_VOLUME_ADDED:
-		/*
-		 * We want to enforce explicit block device creation for
-		 * volumes, so when a volume is added we do nothing.
-		 */
+		ubiblock_create_from_param(&nt->vi);
 		break;
 	case UBI_VOLUME_REMOVED:
 		ubiblock_remove(&nt->vi);
@@ -570,56 +633,6 @@ static struct notifier_block ubiblock_notifier = {
 	.notifier_call = ubiblock_notify,
 };
 
-static struct ubi_volume_desc * __init
-open_volume_desc(const char *name, int ubi_num, int vol_id)
-{
-	if (ubi_num == -1)
-		/* No ubi num, name must be a vol device path */
-		return ubi_open_volume_path(name, UBI_READONLY);
-	else if (vol_id == -1)
-		/* No vol_id, must be vol_name */
-		return ubi_open_volume_nm(ubi_num, name, UBI_READONLY);
-	else
-		return ubi_open_volume(ubi_num, vol_id, UBI_READONLY);
-}
-
-static void __init ubiblock_create_from_param(void)
-{
-	int i, ret = 0;
-	struct ubiblock_param *p;
-	struct ubi_volume_desc *desc;
-	struct ubi_volume_info vi;
-
-	/*
-	 * If there is an error creating one of the ubiblocks, continue on to
-	 * create the following ubiblocks. This helps in a circumstance where
-	 * the kernel command-line specifies multiple block devices and some
-	 * may be broken, but we still want the working ones to come up.
-	 */
-	for (i = 0; i < ubiblock_devs; i++) {
-		p = &ubiblock_param[i];
-
-		desc = open_volume_desc(p->name, p->ubi_num, p->vol_id);
-		if (IS_ERR(desc)) {
-			pr_err(
-			       "UBI: block: can't open volume on ubi%d_%d, err=%ld\n",
-			       p->ubi_num, p->vol_id, PTR_ERR(desc));
-			continue;
-		}
-
-		ubi_get_volume_info(desc, &vi);
-		ubi_close_volume(desc);
-
-		ret = ubiblock_create(&vi);
-		if (ret) {
-			pr_err(
-			       "UBI: block: can't add '%s' volume on ubi%d_%d, err=%d\n",
-			       vi.name, p->ubi_num, p->vol_id, ret);
-			continue;
-		}
-	}
-}
-
 static void ubiblock_remove_all(void)
 {
 	struct ubiblock *next;
@@ -645,18 +658,7 @@ int __init ubiblock_init(void)
 	if (ubiblock_major < 0)
 		return ubiblock_major;
 
-	/*
-	 * Attach block devices from 'block=' module param.
-	 * Even if one block device in the param list fails to come up,
-	 * still allow the module to load and leave any others up.
-	 */
-	ubiblock_create_from_param();
-
-	/*
-	 * Block devices are only created upon user requests, so we ignore
-	 * existing volumes.
-	 */
-	ret = ubi_register_volume_notifier(&ubiblock_notifier, 1);
+	ret = ubi_register_volume_notifier(&ubiblock_notifier, 0);
 	if (ret)
 		goto err_unreg;
 	return 0;
diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index 7d4ff1193d..a7e3a6246c 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -27,6 +27,7 @@
 #include <linux/log2.h>
 #include <linux/kthread.h>
 #include <linux/kernel.h>
+#include <linux/of.h>
 #include <linux/slab.h>
 #include <linux/major.h>
 #include "ubi.h"
@@ -92,7 +93,7 @@ static struct ubi_device *ubi_devices[UBI_MAX_DEVICES];
 /* Serializes UBI devices creations and removals */
 DEFINE_MUTEX(ubi_devices_mutex);
 
-/* Protects @ubi_devices and @ubi->ref_count */
+/* Protects @ubi_devices, @ubi->ref_count and @ubi->is_dead */
 static DEFINE_SPINLOCK(ubi_devices_lock);
 
 /* "Show" method for files in '/<sysfs>/class/ubi/' */
@@ -260,6 +261,9 @@ struct ubi_device *ubi_get_device(int ubi_num)
 
 	spin_lock(&ubi_devices_lock);
 	ubi = ubi_devices[ubi_num];
+	if (ubi && ubi->is_dead)
+		ubi = NULL;
+
 	if (ubi) {
 		ubi_assert(ubi->ref_count >= 0);
 		ubi->ref_count += 1;
@@ -297,7 +301,7 @@ struct ubi_device *ubi_get_by_major(int major)
 	spin_lock(&ubi_devices_lock);
 	for (i = 0; i < UBI_MAX_DEVICES; i++) {
 		ubi = ubi_devices[i];
-		if (ubi && MAJOR(ubi->cdev.dev) == major) {
+		if (ubi && !ubi->is_dead && MAJOR(ubi->cdev.dev) == major) {
 			ubi_assert(ubi->ref_count >= 0);
 			ubi->ref_count += 1;
 			get_device(&ubi->dev);
@@ -326,7 +330,7 @@ int ubi_major2num(int major)
 	for (i = 0; i < UBI_MAX_DEVICES; i++) {
 		struct ubi_device *ubi = ubi_devices[i];
 
-		if (ubi && MAJOR(ubi->cdev.dev) == major) {
+		if (ubi && !ubi->is_dead && MAJOR(ubi->cdev.dev) == major) {
 			ubi_num = ubi->ubi_num;
 			break;
 		}
@@ -513,7 +517,7 @@ static void ubi_free_volumes_from(struct ubi_device *ubi, int from)
 	int i;
 
 	for (i = from; i < ubi->vtbl_slots + UBI_INT_VOL_COUNT; i++) {
-		if (!ubi->volumes[i])
+		if (!ubi->volumes[i] || ubi->volumes[i]->is_dead)
 			continue;
 		ubi_eba_replace_table(ubi->volumes[i], NULL);
 		ubi_fastmap_destroy_checkmap(ubi->volumes[i]);
@@ -1098,7 +1102,6 @@ int ubi_detach_mtd_dev(int ubi_num, int anyway)
 		return -EINVAL;
 
 	spin_lock(&ubi_devices_lock);
-	put_device(&ubi->dev);
 	ubi->ref_count -= 1;
 	if (ubi->ref_count) {
 		if (!anyway) {
@@ -1109,6 +1112,13 @@ int ubi_detach_mtd_dev(int ubi_num, int anyway)
 		ubi_err(ubi, "%s reference count %d, destroy anyway",
 			ubi->ubi_name, ubi->ref_count);
 	}
+	ubi->is_dead = true;
+	spin_unlock(&ubi_devices_lock);
+
+	ubi_notify_all(ubi, UBI_VOLUME_SHUTDOWN, NULL);
+
+	spin_lock(&ubi_devices_lock);
+	put_device(&ubi->dev);
 	ubi_devices[ubi_num] = NULL;
 	spin_unlock(&ubi_devices_lock);
 
@@ -1219,43 +1229,43 @@ static struct mtd_info * __init open_mtd_device(const char *mtd_dev)
 	return mtd;
 }
 
-static int __init ubi_init(void)
+static void ubi_notify_add(struct mtd_info *mtd)
 {
-	int err, i, k;
+	struct device_node *np = mtd_get_of_node(mtd);
+	int err;
 
-	/* Ensure that EC and VID headers have correct size */
-	BUILD_BUG_ON(sizeof(struct ubi_ec_hdr) != 64);
-	BUILD_BUG_ON(sizeof(struct ubi_vid_hdr) != 64);
+	if (!of_device_is_compatible(np, "linux,ubi"))
+		return;
 
-	if (mtd_devs > UBI_MAX_DEVICES) {
-		pr_err("UBI error: too many MTD devices, maximum is %d\n",
-		       UBI_MAX_DEVICES);
-		return -EINVAL;
-	}
+	/*
+	 * we are already holding &mtd_table_mutex, but still need
+	 * to bump refcount
+	 */
+	err = __get_mtd_device(mtd);
+	if (err)
+		return;
 
-	/* Create base sysfs directory and sysfs files */
-	err = class_register(&ubi_class);
+	/* called while holding mtd_table_mutex */
+	mutex_lock_nested(&ubi_devices_mutex, SINGLE_DEPTH_NESTING);
+	err = ubi_attach_mtd_dev(mtd, UBI_DEV_NUM_AUTO, 0, 0, false, false);
+	mutex_unlock(&ubi_devices_mutex);
 	if (err < 0)
-		return err;
-
-	err = misc_register(&ubi_ctrl_cdev);
-	if (err) {
-		pr_err("UBI error: cannot register device\n");
-		goto out;
-	}
+		__put_mtd_device(mtd);
+}
 
-	ubi_wl_entry_slab = kmem_cache_create("ubi_wl_entry_slab",
-					      sizeof(struct ubi_wl_entry),
-					      0, 0, NULL);
-	if (!ubi_wl_entry_slab) {
-		err = -ENOMEM;
-		goto out_dev_unreg;
-	}
+static void ubi_notify_remove(struct mtd_info *mtd)
+{
+	/* do nothing for now */
+}
 
-	err = ubi_debugfs_init();
-	if (err)
-		goto out_slab;
+static struct mtd_notifier ubi_mtd_notifier = {
+	.add = ubi_notify_add,
+	.remove = ubi_notify_remove,
+};
 
+static int __init ubi_init_attach(void)
+{
+	int err, i, k;
 
 	/* Attach MTD devices */
 	for (i = 0; i < mtd_devs; i++) {
@@ -1304,25 +1314,79 @@ static int __init ubi_init(void)
 		}
 	}
 
+	return 0;
+
+out_detach:
+	for (k = 0; k < i; k++)
+		if (ubi_devices[k]) {
+			mutex_lock(&ubi_devices_mutex);
+			ubi_detach_mtd_dev(ubi_devices[k]->ubi_num, 1);
+			mutex_unlock(&ubi_devices_mutex);
+		}
+	return err;
+}
+#ifndef CONFIG_MTD_UBI_MODULE
+late_initcall(ubi_init_attach);
+#endif
+
+static int __init ubi_init(void)
+{
+	int err;
+
+	/* Ensure that EC and VID headers have correct size */
+	BUILD_BUG_ON(sizeof(struct ubi_ec_hdr) != 64);
+	BUILD_BUG_ON(sizeof(struct ubi_vid_hdr) != 64);
+
+	if (mtd_devs > UBI_MAX_DEVICES) {
+		pr_err("UBI error: too many MTD devices, maximum is %d\n",
+		       UBI_MAX_DEVICES);
+		return -EINVAL;
+	}
+
+	/* Create base sysfs directory and sysfs files */
+	err = class_register(&ubi_class);
+	if (err < 0)
+		return err;
+
+	err = misc_register(&ubi_ctrl_cdev);
+	if (err) {
+		pr_err("UBI error: cannot register device\n");
+		goto out;
+	}
+
+	ubi_wl_entry_slab = kmem_cache_create("ubi_wl_entry_slab",
+					      sizeof(struct ubi_wl_entry),
+					      0, 0, NULL);
+	if (!ubi_wl_entry_slab) {
+		err = -ENOMEM;
+		goto out_dev_unreg;
+	}
+
+	err = ubi_debugfs_init();
+	if (err)
+		goto out_slab;
+
 	err = ubiblock_init();
 	if (err) {
 		pr_err("UBI error: block: cannot initialize, error %d\n", err);
 
 		/* See comment above re-ubi_is_module(). */
 		if (ubi_is_module())
-			goto out_detach;
+			goto out_slab;
+	}
+
+	register_mtd_user(&ubi_mtd_notifier);
+
+	if (ubi_is_module()) {
+		err = ubi_init_attach();
+		if (err)
+			goto out_mtd_notifier;
 	}
 
 	return 0;
 
-out_detach:
-	for (k = 0; k < i; k++)
-		if (ubi_devices[k]) {
-			mutex_lock(&ubi_devices_mutex);
-			ubi_detach_mtd_dev(ubi_devices[k]->ubi_num, 1);
-			mutex_unlock(&ubi_devices_mutex);
-		}
-	ubi_debugfs_exit();
+out_mtd_notifier:
+	unregister_mtd_user(&ubi_mtd_notifier);
 out_slab:
 	kmem_cache_destroy(ubi_wl_entry_slab);
 out_dev_unreg:
@@ -1332,13 +1396,15 @@ out:
 	pr_err("UBI error: cannot initialize UBI, error %d\n", err);
 	return err;
 }
-late_initcall(ubi_init);
+device_initcall(ubi_init);
+
 
 static void __exit ubi_exit(void)
 {
 	int i;
 
 	ubiblock_exit();
+	unregister_mtd_user(&ubi_mtd_notifier);
 
 	for (i = 0; i < UBI_MAX_DEVICES; i++)
 		if (ubi_devices[i]) {
diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
index 8d1f0e0589..e5ac3cd0bb 100644
--- a/drivers/mtd/ubi/eba.c
+++ b/drivers/mtd/ubi/eba.c
@@ -1456,7 +1456,14 @@ int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
 	}
 
 	ubi_assert(vol->eba_tbl->entries[lnum].pnum == from);
+
+	/**
+	 * The volumes_lock lock is needed here to prevent the expired old eba_tbl
+	 * being updated when the eba_tbl is copied in the ubi_resize_volume() process.
+	 */
+	spin_lock(&ubi->volumes_lock);
 	vol->eba_tbl->entries[lnum].pnum = to;
+	spin_unlock(&ubi->volumes_lock);
 
 out_unlock_buf:
 	mutex_unlock(&ubi->buf_mutex);
diff --git a/drivers/mtd/ubi/kapi.c b/drivers/mtd/ubi/kapi.c
index 5db653eacb..f1ea867746 100644
--- a/drivers/mtd/ubi/kapi.c
+++ b/drivers/mtd/ubi/kapi.c
@@ -152,7 +152,7 @@ struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode)
 
 	spin_lock(&ubi->volumes_lock);
 	vol = ubi->volumes[vol_id];
-	if (!vol)
+	if (!vol || vol->is_dead)
 		goto out_unlock;
 
 	err = -EBUSY;
@@ -280,6 +280,41 @@ struct ubi_volume_desc *ubi_open_volume_nm(int ubi_num, const char *name,
 EXPORT_SYMBOL_GPL(ubi_open_volume_nm);
 
 /**
+ * ubi_get_num_by_path - get UBI device and volume number from device path
+ * @pathname: volume character device node path
+ * @ubi_num: pointer to UBI device number to be set
+ * @vol_id: pointer to UBI volume ID to be set
+ *
+ * Returns 0 on success and sets ubi_num and vol_id, returns error otherwise.
+ */
+int ubi_get_num_by_path(const char *pathname, int *ubi_num, int *vol_id)
+{
+	int error;
+	struct path path;
+	struct kstat stat;
+
+	error = kern_path(pathname, LOOKUP_FOLLOW, &path);
+	if (error)
+		return error;
+
+	error = vfs_getattr(&path, &stat, STATX_TYPE, AT_STATX_SYNC_AS_STAT);
+	path_put(&path);
+	if (error)
+		return error;
+
+	if (!S_ISCHR(stat.mode))
+		return -EINVAL;
+
+	*ubi_num = ubi_major2num(MAJOR(stat.rdev));
+	*vol_id = MINOR(stat.rdev) - 1;
+
+	if (*vol_id < 0 || *ubi_num < 0)
+		return -ENODEV;
+
+	return 0;
+}
+
+/**
  * ubi_open_volume_path - open UBI volume by its character device node path.
  * @pathname: volume character device node path
  * @mode: open mode
@@ -290,32 +325,17 @@ EXPORT_SYMBOL_GPL(ubi_open_volume_nm);
 struct ubi_volume_desc *ubi_open_volume_path(const char *pathname, int mode)
 {
 	int error, ubi_num, vol_id;
-	struct path path;
-	struct kstat stat;
 
 	dbg_gen("open volume %s, mode %d", pathname, mode);
 
 	if (!pathname || !*pathname)
 		return ERR_PTR(-EINVAL);
 
-	error = kern_path(pathname, LOOKUP_FOLLOW, &path);
-	if (error)
-		return ERR_PTR(error);
-
-	error = vfs_getattr(&path, &stat, STATX_TYPE, AT_STATX_SYNC_AS_STAT);
-	path_put(&path);
+	error = ubi_get_num_by_path(pathname, &ubi_num, &vol_id);
 	if (error)
 		return ERR_PTR(error);
 
-	if (!S_ISCHR(stat.mode))
-		return ERR_PTR(-EINVAL);
-
-	ubi_num = ubi_major2num(MAJOR(stat.rdev));
-	vol_id = MINOR(stat.rdev) - 1;
-
-	if (vol_id >= 0 && ubi_num >= 0)
-		return ubi_open_volume(ubi_num, vol_id, mode);
-	return ERR_PTR(-ENODEV);
+	return ubi_open_volume(ubi_num, vol_id, mode);
 }
 EXPORT_SYMBOL_GPL(ubi_open_volume_path);
 
diff --git a/drivers/mtd/ubi/nvmem.c b/drivers/mtd/ubi/nvmem.c
new file mode 100644
index 0000000000..8aeb9c428e
--- /dev/null
+++ b/drivers/mtd/ubi/nvmem.c
@@ -0,0 +1,191 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2023 Daniel Golle <daniel@makrotopia.org>
+ */
+
+/* UBI NVMEM provider */
+#include "ubi.h"
+#include <linux/nvmem-provider.h>
+#include <asm/div64.h>
+
+/* List of all NVMEM devices */
+static LIST_HEAD(nvmem_devices);
+static DEFINE_MUTEX(devices_mutex);
+
+struct ubi_nvmem {
+	struct nvmem_device *nvmem;
+	int ubi_num;
+	int vol_id;
+	int usable_leb_size;
+	struct list_head list;
+};
+
+static int ubi_nvmem_reg_read(void *priv, unsigned int from,
+			      void *val, size_t bytes)
+{
+	size_t to_read, bytes_left = bytes;
+	struct ubi_nvmem *unv = priv;
+	struct ubi_volume_desc *desc;
+	uint32_t offs;
+	uint64_t lnum = from;
+	int err = 0;
+
+	desc = ubi_open_volume(unv->ubi_num, unv->vol_id, UBI_READONLY);
+	if (IS_ERR(desc))
+		return PTR_ERR(desc);
+
+	offs = do_div(lnum, unv->usable_leb_size);
+	while (bytes_left) {
+		to_read = unv->usable_leb_size - offs;
+
+		if (to_read > bytes_left)
+			to_read = bytes_left;
+
+		err = ubi_read(desc, lnum, val, offs, to_read);
+		if (err)
+			break;
+
+		lnum += 1;
+		offs = 0;
+		bytes_left -= to_read;
+		val += to_read;
+	}
+	ubi_close_volume(desc);
+
+	if (err)
+		return err;
+
+	return bytes_left == 0 ? 0 : -EIO;
+}
+
+static int ubi_nvmem_add(struct ubi_volume_info *vi)
+{
+	struct device_node *np = dev_of_node(vi->dev);
+	struct nvmem_config config = {};
+	struct ubi_nvmem *unv;
+	int ret;
+
+	if (!np)
+		return 0;
+
+	if (!of_get_child_by_name(np, "nvmem-layout"))
+		return 0;
+
+	if (WARN_ON_ONCE(vi->usable_leb_size <= 0) ||
+	    WARN_ON_ONCE(vi->size <= 0))
+		return -EINVAL;
+
+	unv = kzalloc(sizeof(struct ubi_nvmem), GFP_KERNEL);
+	if (!unv)
+		return -ENOMEM;
+
+	config.id = NVMEM_DEVID_NONE;
+	config.dev = vi->dev;
+	config.name = dev_name(vi->dev);
+	config.owner = THIS_MODULE;
+	config.priv = unv;
+	config.reg_read = ubi_nvmem_reg_read;
+	config.size = vi->usable_leb_size * vi->size;
+	config.word_size = 1;
+	config.stride = 1;
+	config.read_only = true;
+	config.root_only = true;
+	config.ignore_wp = true;
+	config.of_node = np;
+
+	unv->ubi_num = vi->ubi_num;
+	unv->vol_id = vi->vol_id;
+	unv->usable_leb_size = vi->usable_leb_size;
+	unv->nvmem = nvmem_register(&config);
+	if (IS_ERR(unv->nvmem)) {
+		ret = dev_err_probe(vi->dev, PTR_ERR(unv->nvmem),
+				    "Failed to register NVMEM device\n");
+		kfree(unv);
+		return ret;
+	}
+
+	mutex_lock(&devices_mutex);
+	list_add_tail(&unv->list, &nvmem_devices);
+	mutex_unlock(&devices_mutex);
+
+	return 0;
+}
+
+static void ubi_nvmem_remove(struct ubi_volume_info *vi)
+{
+	struct ubi_nvmem *unv_c, *unv = NULL;
+
+	mutex_lock(&devices_mutex);
+	list_for_each_entry(unv_c, &nvmem_devices, list)
+		if (unv_c->ubi_num == vi->ubi_num && unv_c->vol_id == vi->vol_id) {
+			unv = unv_c;
+			break;
+		}
+
+	if (!unv) {
+		mutex_unlock(&devices_mutex);
+		return;
+	}
+
+	list_del(&unv->list);
+	mutex_unlock(&devices_mutex);
+	nvmem_unregister(unv->nvmem);
+	kfree(unv);
+}
+
+/**
+ * nvmem_notify - UBI notification handler.
+ * @nb: registered notifier block
+ * @l: notification type
+ * @ns_ptr: pointer to the &struct ubi_notification object
+ */
+static int nvmem_notify(struct notifier_block *nb, unsigned long l,
+			 void *ns_ptr)
+{
+	struct ubi_notification *nt = ns_ptr;
+
+	switch (l) {
+	case UBI_VOLUME_RESIZED:
+		ubi_nvmem_remove(&nt->vi);
+		fallthrough;
+	case UBI_VOLUME_ADDED:
+		ubi_nvmem_add(&nt->vi);
+		break;
+	case UBI_VOLUME_SHUTDOWN:
+		ubi_nvmem_remove(&nt->vi);
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block nvmem_notifier = {
+	.notifier_call = nvmem_notify,
+};
+
+static int __init ubi_nvmem_init(void)
+{
+	return ubi_register_volume_notifier(&nvmem_notifier, 0);
+}
+
+static void __exit ubi_nvmem_exit(void)
+{
+	struct ubi_nvmem *unv, *tmp;
+
+	mutex_lock(&devices_mutex);
+	list_for_each_entry_safe(unv, tmp, &nvmem_devices, list) {
+		nvmem_unregister(unv->nvmem);
+		list_del(&unv->list);
+		kfree(unv);
+	}
+	mutex_unlock(&devices_mutex);
+
+	ubi_unregister_volume_notifier(&nvmem_notifier);
+}
+
+module_init(ubi_nvmem_init);
+module_exit(ubi_nvmem_exit);
+MODULE_DESCRIPTION("NVMEM layer over UBI volumes");
+MODULE_AUTHOR("Daniel Golle");
+MODULE_LICENSE("GPL");
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 0b42bb45dd..32009a2486 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -337,6 +337,7 @@ struct ubi_volume {
 	int writers;
 	int exclusive;
 	int metaonly;
+	bool is_dead;
 
 	int reserved_pebs;
 	int vol_type;
@@ -561,6 +562,7 @@ struct ubi_device {
 	spinlock_t volumes_lock;
 	int ref_count;
 	int image_seq;
+	bool is_dead;
 
 	int rsvd_pebs;
 	int avail_pebs;
@@ -955,6 +957,7 @@ void ubi_free_internal_volumes(struct ubi_device *ubi);
 void ubi_do_get_device_info(struct ubi_device *ubi, struct ubi_device_info *di);
 void ubi_do_get_volume_info(struct ubi_device *ubi, struct ubi_volume *vol,
 			    struct ubi_volume_info *vi);
+int ubi_get_num_by_path(const char *pathname, int *ubi_num, int *vol_id);
 /* scan.c */
 int ubi_compare_lebs(struct ubi_device *ubi, const struct ubi_ainf_peb *aeb,
 		      int pnum, const struct ubi_vid_hdr *vid_hdr);
diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c
index 2c867d16f8..5a3558bbb9 100644
--- a/drivers/mtd/ubi/vmt.c
+++ b/drivers/mtd/ubi/vmt.c
@@ -59,7 +59,7 @@ static ssize_t vol_attribute_show(struct device *dev,
 	struct ubi_device *ubi = vol->ubi;
 
 	spin_lock(&ubi->volumes_lock);
-	if (!ubi->volumes[vol->vol_id]) {
+	if (!ubi->volumes[vol->vol_id] || ubi->volumes[vol->vol_id]->is_dead) {
 		spin_unlock(&ubi->volumes_lock);
 		return -ENODEV;
 	}
@@ -124,6 +124,31 @@ static void vol_release(struct device *dev)
 	kfree(vol);
 }
 
+static struct fwnode_handle *find_volume_fwnode(struct ubi_volume *vol)
+{
+	struct fwnode_handle *fw_vols, *fw_vol;
+	const char *volname;
+	u32 volid;
+
+	fw_vols = device_get_named_child_node(vol->dev.parent->parent, "volumes");
+	if (!fw_vols)
+		return NULL;
+
+	fwnode_for_each_child_node(fw_vols, fw_vol) {
+		if (!fwnode_property_read_string(fw_vol, "volname", &volname) &&
+		    strncmp(volname, vol->name, vol->name_len))
+			continue;
+
+		if (!fwnode_property_read_u32(fw_vol, "volid", &volid) &&
+		    vol->vol_id != volid)
+			continue;
+
+		return fw_vol;
+	}
+
+	return NULL;
+}
+
 /**
  * ubi_create_volume - create volume.
  * @ubi: UBI device description object
@@ -189,7 +214,7 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
 
 	/* Ensure that the name is unique */
 	for (i = 0; i < ubi->vtbl_slots; i++)
-		if (ubi->volumes[i] &&
+		if (ubi->volumes[i] && !ubi->volumes[i]->is_dead &&
 		    ubi->volumes[i]->name_len == req->name_len &&
 		    !strcmp(ubi->volumes[i]->name, req->name)) {
 			ubi_err(ubi, "volume \"%s\" exists (ID %d)",
@@ -223,6 +248,7 @@ int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
 	vol->name_len  = req->name_len;
 	memcpy(vol->name, req->name, vol->name_len);
 	vol->ubi = ubi;
+	device_set_node(&vol->dev, find_volume_fwnode(vol));
 
 	/*
 	 * Finish all pending erases because there may be some LEBs belonging
@@ -352,6 +378,19 @@ int ubi_remove_volume(struct ubi_volume_desc *desc, int no_vtbl)
 		err = -EBUSY;
 		goto out_unlock;
 	}
+
+	/*
+	 * Mark volume as dead at this point to prevent that anyone
+	 * can take a reference to the volume from now on.
+	 * This is necessary as we have to release the spinlock before
+	 * calling ubi_volume_notify.
+	 */
+	vol->is_dead = true;
+	spin_unlock(&ubi->volumes_lock);
+
+	ubi_volume_notify(ubi, vol, UBI_VOLUME_SHUTDOWN);
+
+	spin_lock(&ubi->volumes_lock);
 	ubi->volumes[vol_id] = NULL;
 	spin_unlock(&ubi->volumes_lock);
 
@@ -408,6 +447,7 @@ int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs)
 	struct ubi_device *ubi = vol->ubi;
 	struct ubi_vtbl_record vtbl_rec;
 	struct ubi_eba_table *new_eba_tbl = NULL;
+	struct ubi_eba_table *old_eba_tbl = NULL;
 	int vol_id = vol->vol_id;
 
 	if (ubi->ro_mode)
@@ -453,10 +493,13 @@ int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs)
 			err = -ENOSPC;
 			goto out_free;
 		}
+
 		ubi->avail_pebs -= pebs;
 		ubi->rsvd_pebs += pebs;
 		ubi_eba_copy_table(vol, new_eba_tbl, vol->reserved_pebs);
-		ubi_eba_replace_table(vol, new_eba_tbl);
+		old_eba_tbl = vol->eba_tbl;
+		vol->eba_tbl = new_eba_tbl;
+		vol->reserved_pebs = reserved_pebs;
 		spin_unlock(&ubi->volumes_lock);
 	}
 
@@ -471,7 +514,9 @@ int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs)
 		ubi->avail_pebs -= pebs;
 		ubi_update_reserved(ubi);
 		ubi_eba_copy_table(vol, new_eba_tbl, reserved_pebs);
-		ubi_eba_replace_table(vol, new_eba_tbl);
+		old_eba_tbl = vol->eba_tbl;
+		vol->eba_tbl = new_eba_tbl;
+		vol->reserved_pebs = reserved_pebs;
 		spin_unlock(&ubi->volumes_lock);
 	}
 
@@ -493,7 +538,6 @@ int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs)
 	if (err)
 		goto out_acc;
 
-	vol->reserved_pebs = reserved_pebs;
 	if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
 		vol->used_ebs = reserved_pebs;
 		vol->last_eb_bytes = vol->usable_leb_size;
@@ -501,19 +545,23 @@ int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs)
 			(long long)vol->used_ebs * vol->usable_leb_size;
 	}
 
+	/* destroy old table */
+	ubi_eba_destroy_table(old_eba_tbl);
 	ubi_volume_notify(ubi, vol, UBI_VOLUME_RESIZED);
 	self_check_volumes(ubi);
 	return err;
 
 out_acc:
-	if (pebs > 0) {
-		spin_lock(&ubi->volumes_lock);
-		ubi->rsvd_pebs -= pebs;
-		ubi->avail_pebs += pebs;
-		spin_unlock(&ubi->volumes_lock);
-	}
-	return err;
-
+	spin_lock(&ubi->volumes_lock);
+	vol->reserved_pebs = reserved_pebs - pebs;
+	ubi->rsvd_pebs -= pebs;
+	ubi->avail_pebs += pebs;
+	if (pebs > 0)
+		ubi_eba_copy_table(vol, old_eba_tbl, vol->reserved_pebs);
+	else
+		ubi_eba_copy_table(vol, old_eba_tbl, reserved_pebs);
+	vol->eba_tbl = old_eba_tbl;
+	spin_unlock(&ubi->volumes_lock);
 out_free:
 	ubi_eba_destroy_table(new_eba_tbl);
 	return err;
@@ -592,6 +640,7 @@ int ubi_add_volume(struct ubi_device *ubi, struct ubi_volume *vol)
 	vol->dev.class = &ubi_class;
 	vol->dev.groups = volume_dev_groups;
 	dev_set_name(&vol->dev, "%s_%d", ubi->ubi_name, vol->vol_id);
+	device_set_node(&vol->dev, find_volume_fwnode(vol));
 	err = device_register(&vol->dev);
 	if (err) {
 		cdev_del(&vol->cdev);