12 files changed, 585 insertions, 225 deletions

diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index 5bc9c4874fe3..283134498fbc 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 menuconfig NVMEM
 	bool "NVMEM Support"
+	imply NVMEM_LAYOUTS
 	help
 	  Support for NVMEM(Non Volatile Memory) devices like EEPROM, EFUSES...
 
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index 423baf089515..cdd01fbf1313 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -5,6 +5,8 @@
 
 obj-$(CONFIG_NVMEM)		+= nvmem_core.o
 nvmem_core-y			:= core.o
+obj-$(CONFIG_NVMEM_LAYOUTS)	+= nvmem_layouts.o
+nvmem_layouts-y			:= layouts.o
 obj-y				+= layouts/
 
 # Devices
diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 608b352a7d91..980123fb4dde 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -19,29 +19,7 @@
 #include <linux/of.h>
 #include <linux/slab.h>
 
-struct nvmem_device {
-	struct module		*owner;
-	struct device		dev;
-	int			stride;
-	int			word_size;
-	int			id;
-	struct kref		refcnt;
-	size_t			size;
-	bool			read_only;
-	bool			root_only;
-	int			flags;
-	enum nvmem_type		type;
-	struct bin_attribute	eeprom;
-	struct device		*base_dev;
-	struct list_head	cells;
-	const struct nvmem_keepout *keepout;
-	unsigned int		nkeepout;
-	nvmem_reg_read_t	reg_read;
-	nvmem_reg_write_t	reg_write;
-	struct gpio_desc	*wp_gpio;
-	struct nvmem_layout	*layout;
-	void *priv;
-};
+#include "internals.h"
 
 #define to_nvmem_device(d) container_of(d, struct nvmem_device, dev)
 
@@ -77,9 +55,6 @@ static LIST_HEAD(nvmem_lookup_list);
 
 static BLOCKING_NOTIFIER_HEAD(nvmem_notifier);
 
-static DEFINE_SPINLOCK(nvmem_layout_lock);
-static LIST_HEAD(nvmem_layouts);
-
 static int __nvmem_reg_read(struct nvmem_device *nvmem, unsigned int offset,
 			    void *val, size_t bytes)
 {
@@ -324,6 +299,43 @@ static umode_t nvmem_bin_attr_is_visible(struct kobject *kobj,
 	return nvmem_bin_attr_get_umode(nvmem);
 }
 
+static struct nvmem_cell *nvmem_create_cell(struct nvmem_cell_entry *entry,
+					    const char *id, int index);
+
+static ssize_t nvmem_cell_attr_read(struct file *filp, struct kobject *kobj,
+				    struct bin_attribute *attr, char *buf,
+				    loff_t pos, size_t count)
+{
+	struct nvmem_cell_entry *entry;
+	struct nvmem_cell *cell = NULL;
+	size_t cell_sz, read_len;
+	void *content;
+
+	entry = attr->private;
+	cell = nvmem_create_cell(entry, entry->name, 0);
+	if (IS_ERR(cell))
+		return PTR_ERR(cell);
+
+	if (!cell)
+		return -EINVAL;
+
+	content = nvmem_cell_read(cell, &cell_sz);
+	if (IS_ERR(content)) {
+		read_len = PTR_ERR(content);
+		goto destroy_cell;
+	}
+
+	read_len = min_t(unsigned int, cell_sz - pos, count);
+	memcpy(buf, content + pos, read_len);
+	kfree(content);
+
+destroy_cell:
+	kfree_const(cell->id);
+	kfree(cell);
+
+	return read_len;
+}
+
 /* default read/write permissions */
 static struct bin_attribute bin_attr_rw_nvmem = {
 	.attr	= {
@@ -345,11 +357,21 @@ static const struct attribute_group nvmem_bin_group = {
 	.is_bin_visible = nvmem_bin_attr_is_visible,
 };
 
+/* Cell attributes will be dynamically allocated */
+static struct attribute_group nvmem_cells_group = {
+	.name		= "cells",
+};
+
 static const struct attribute_group *nvmem_dev_groups[] = {
 	&nvmem_bin_group,
 	NULL,
 };
 
+static const struct attribute_group *nvmem_cells_groups[] = {
+	&nvmem_cells_group,
+	NULL,
+};
+
 static struct bin_attribute bin_attr_nvmem_eeprom_compat = {
 	.attr	= {
 		.name	= "eeprom",
@@ -405,6 +427,68 @@ static void nvmem_sysfs_remove_compat(struct nvmem_device *nvmem,
 		device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 }
 
+static int nvmem_populate_sysfs_cells(struct nvmem_device *nvmem)
+{
+	struct bin_attribute **cells_attrs, *attrs;
+	struct nvmem_cell_entry *entry;
+	unsigned int ncells = 0, i = 0;
+	int ret = 0;
+
+	mutex_lock(&nvmem_mutex);
+
+	if (list_empty(&nvmem->cells) || nvmem->sysfs_cells_populated) {
+		nvmem_cells_group.bin_attrs = NULL;
+		goto unlock_mutex;
+	}
+
+	/* Allocate an array of attributes with a sentinel */
+	ncells = list_count_nodes(&nvmem->cells);
+	cells_attrs = devm_kcalloc(&nvmem->dev, ncells + 1,
+				   sizeof(struct bin_attribute *), GFP_KERNEL);
+	if (!cells_attrs) {
+		ret = -ENOMEM;
+		goto unlock_mutex;
+	}
+
+	attrs = devm_kcalloc(&nvmem->dev, ncells, sizeof(struct bin_attribute), GFP_KERNEL);
+	if (!attrs) {
+		ret = -ENOMEM;
+		goto unlock_mutex;
+	}
+
+	/* Initialize each attribute to take the name and size of the cell */
+	list_for_each_entry(entry, &nvmem->cells, node) {
+		sysfs_bin_attr_init(&attrs[i]);
+		attrs[i].attr.name = devm_kasprintf(&nvmem->dev, GFP_KERNEL,
+						    "%s@%x", entry->name,
+						    entry->offset);
+		attrs[i].attr.mode = 0444;
+		attrs[i].size = entry->bytes;
+		attrs[i].read = &nvmem_cell_attr_read;
+		attrs[i].private = entry;
+		if (!attrs[i].attr.name) {
+			ret = -ENOMEM;
+			goto unlock_mutex;
+		}
+
+		cells_attrs[i] = &attrs[i];
+		i++;
+	}
+
+	nvmem_cells_group.bin_attrs = cells_attrs;
+
+	ret = devm_device_add_groups(&nvmem->dev, nvmem_cells_groups);
+	if (ret)
+		goto unlock_mutex;
+
+	nvmem->sysfs_cells_populated = true;
+
+unlock_mutex:
+	mutex_unlock(&nvmem_mutex);
+
+	return ret;
+}
+
 #else /* CONFIG_NVMEM_SYSFS */
 
 static int nvmem_sysfs_setup_compat(struct nvmem_device *nvmem,
@@ -697,7 +781,6 @@ static int nvmem_validate_keepouts(struct nvmem_device *nvmem)
 
 static int nvmem_add_cells_from_dt(struct nvmem_device *nvmem, struct device_node *np)
 {
-	struct nvmem_layout *layout = nvmem->layout;
 	struct device *dev = &nvmem->dev;
 	struct device_node *child;
 	const __be32 *addr;
@@ -727,8 +810,8 @@ static int nvmem_add_cells_from_dt(struct nvmem_device *nvmem, struct device_nod
 
 		info.np = of_node_get(child);
 
-		if (layout && layout->fixup_cell_info)
-			layout->fixup_cell_info(nvmem, layout, &info);
+		if (nvmem->fixup_dt_cell_info)
+			nvmem->fixup_dt_cell_info(nvmem, &info);
 
 		ret = nvmem_add_one_cell(nvmem, &info);
 		kfree(info.name);
@@ -763,117 +846,35 @@ static int nvmem_add_cells_from_fixed_layout(struct nvmem_device *nvmem)
 	return err;
 }
 
-int __nvmem_layout_register(struct nvmem_layout *layout, struct module *owner)
-{
-	layout->owner = owner;
-
-	spin_lock(&nvmem_layout_lock);
-	list_add(&layout->node, &nvmem_layouts);
-	spin_unlock(&nvmem_layout_lock);
-
-	blocking_notifier_call_chain(&nvmem_notifier, NVMEM_LAYOUT_ADD, layout);
-
-	return 0;
-}
-EXPORT_SYMBOL_GPL(__nvmem_layout_register);
-
-void nvmem_layout_unregister(struct nvmem_layout *layout)
-{
-	blocking_notifier_call_chain(&nvmem_notifier, NVMEM_LAYOUT_REMOVE, layout);
-
-	spin_lock(&nvmem_layout_lock);
-	list_del(&layout->node);
-	spin_unlock(&nvmem_layout_lock);
-}
-EXPORT_SYMBOL_GPL(nvmem_layout_unregister);
-
-static struct nvmem_layout *nvmem_layout_get(struct nvmem_device *nvmem)
+int nvmem_layout_register(struct nvmem_layout *layout)
 {
-	struct device_node *layout_np;
-	struct nvmem_layout *l, *layout = ERR_PTR(-EPROBE_DEFER);
-
-	layout_np = of_nvmem_layout_get_container(nvmem);
-	if (!layout_np)
-		return NULL;
-
-	/* Fixed layouts don't have a matching driver */
-	if (of_device_is_compatible(layout_np, "fixed-layout")) {
-		of_node_put(layout_np);
-		return NULL;
-	}
-
-	/*
-	 * In case the nvmem device was built-in while the layout was built as a
-	 * module, we shall manually request the layout driver loading otherwise
-	 * we'll never have any match.
-	 */
-	of_request_module(layout_np);
-
-	spin_lock(&nvmem_layout_lock);
-
-	list_for_each_entry(l, &nvmem_layouts, node) {
-		if (of_match_node(l->of_match_table, layout_np)) {
-			if (try_module_get(l->owner))
-				layout = l;
-
-			break;
-		}
-	}
-
-	spin_unlock(&nvmem_layout_lock);
-	of_node_put(layout_np);
-
-	return layout;
-}
+	int ret;
 
-static void nvmem_layout_put(struct nvmem_layout *layout)
-{
-	if (layout)
-		module_put(layout->owner);
-}
+	if (!layout->add_cells)
+		return -EINVAL;
 
-static int nvmem_add_cells_from_layout(struct nvmem_device *nvmem)
-{
-	struct nvmem_layout *layout = nvmem->layout;
-	int ret;
+	/* Populate the cells */
+	ret = layout->add_cells(layout);
+	if (ret)
+		return ret;
 
-	if (layout && layout->add_cells) {
-		ret = layout->add_cells(&nvmem->dev, nvmem, layout);
-		if (ret)
-			return ret;
+#ifdef CONFIG_NVMEM_SYSFS
+	ret = nvmem_populate_sysfs_cells(layout->nvmem);
+	if (ret) {
+		nvmem_device_remove_all_cells(layout->nvmem);
+		return ret;
 	}
+#endif
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(nvmem_layout_register);
 
-#if IS_ENABLED(CONFIG_OF)
-/**
- * of_nvmem_layout_get_container() - Get OF node to layout container.
- *
- * @nvmem: nvmem device.
- *
- * Return: a node pointer with refcount incremented or NULL if no
- * container exists. Use of_node_put() on it when done.
- */
-struct device_node *of_nvmem_layout_get_container(struct nvmem_device *nvmem)
-{
-	return of_get_child_by_name(nvmem->dev.of_node, "nvmem-layout");
-}
-EXPORT_SYMBOL_GPL(of_nvmem_layout_get_container);
-#endif
-
-const void *nvmem_layout_get_match_data(struct nvmem_device *nvmem,
-					struct nvmem_layout *layout)
+void nvmem_layout_unregister(struct nvmem_layout *layout)
 {
-	struct device_node __maybe_unused *layout_np;
-	const struct of_device_id *match;
-
-	layout_np = of_nvmem_layout_get_container(nvmem);
-	match = of_match_node(layout->of_match_table, layout_np);
-
-	return match ? match->data : NULL;
+	/* Keep the API even with an empty stub in case we need it later */
 }
-EXPORT_SYMBOL_GPL(nvmem_layout_get_match_data);
+EXPORT_SYMBOL_GPL(nvmem_layout_unregister);
 
 /**
  * nvmem_register() - Register a nvmem device for given nvmem_config.
@@ -925,6 +926,7 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 
 	kref_init(&nvmem->refcnt);
 	INIT_LIST_HEAD(&nvmem->cells);
+	nvmem->fixup_dt_cell_info = config->fixup_dt_cell_info;
 
 	nvmem->owner = config->owner;
 	if (!nvmem->owner && config->dev->driver)
@@ -980,19 +982,6 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 			goto err_put_device;
 	}
 
-	/*
-	 * If the driver supplied a layout by config->layout, the module
-	 * pointer will be NULL and nvmem_layout_put() will be a noop.
-	 */
-	nvmem->layout = config->layout ?: nvmem_layout_get(nvmem);
-	if (IS_ERR(nvmem->layout)) {
-		rval = PTR_ERR(nvmem->layout);
-		nvmem->layout = NULL;
-
-		if (rval == -EPROBE_DEFER)
-			goto err_teardown_compat;
-	}
-
 	if (config->cells) {
 		rval = nvmem_add_cells(nvmem, config->cells, config->ncells);
 		if (rval)
@@ -1013,24 +1002,34 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
 	if (rval)
 		goto err_remove_cells;
 
-	rval = nvmem_add_cells_from_layout(nvmem);
-	if (rval)
-		goto err_remove_cells;
-
 	dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name);
 
 	rval = device_add(&nvmem->dev);
 	if (rval)
 		goto err_remove_cells;
 
+	rval = nvmem_populate_layout(nvmem);
+	if (rval)
+		goto err_remove_dev;
+
+#ifdef CONFIG_NVMEM_SYSFS
+	rval = nvmem_populate_sysfs_cells(nvmem);
+	if (rval)
+		goto err_destroy_layout;
+#endif
+
 	blocking_notifier_call_chain(&nvmem_notifier, NVMEM_ADD, nvmem);
 
 	return nvmem;
 
+#ifdef CONFIG_NVMEM_SYSFS
+err_destroy_layout:
+	nvmem_destroy_layout(nvmem);
+#endif
+err_remove_dev:
+	device_del(&nvmem->dev);
 err_remove_cells:
 	nvmem_device_remove_all_cells(nvmem);
-	nvmem_layout_put(nvmem->layout);
-err_teardown_compat:
 	if (config->compat)
 		nvmem_sysfs_remove_compat(nvmem, config);
 err_put_device:
@@ -1052,7 +1051,7 @@ static void nvmem_device_release(struct kref *kref)
 		device_remove_bin_file(nvmem->base_dev, &nvmem->eeprom);
 
 	nvmem_device_remove_all_cells(nvmem);
-	nvmem_layout_put(nvmem->layout);
+	nvmem_destroy_layout(nvmem);
 	device_unregister(&nvmem->dev);
 }
 
@@ -1354,6 +1353,12 @@ nvmem_cell_get_from_lookup(struct device *dev, const char *con_id)
 	return cell;
 }
 
+static void nvmem_layout_module_put(struct nvmem_device *nvmem)
+{
+	if (nvmem->layout && nvmem->layout->dev.driver)
+		module_put(nvmem->layout->dev.driver->owner);
+}
+
 #if IS_ENABLED(CONFIG_OF)
 static struct nvmem_cell_entry *
 nvmem_find_cell_entry_by_node(struct nvmem_device *nvmem, struct device_node *np)
@@ -1372,6 +1377,18 @@ nvmem_find_cell_entry_by_node(struct nvmem_device *nvmem, struct device_node *np
 	return cell;
 }
 
+static int nvmem_layout_module_get_optional(struct nvmem_device *nvmem)
+{
+	if (!nvmem->layout)
+		return 0;
+
+	if (!nvmem->layout->dev.driver ||
+	    !try_module_get(nvmem->layout->dev.driver->owner))
+		return -EPROBE_DEFER;
+
+	return 0;
+}
+
 /**
  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
  *
@@ -1434,16 +1451,29 @@ struct nvmem_cell *of_nvmem_cell_get(struct device_node *np, const char *id)
 		return ERR_CAST(nvmem);
 	}
 
+	ret = nvmem_layout_module_get_optional(nvmem);
+	if (ret) {
+		of_node_put(cell_np);
+		__nvmem_device_put(nvmem);
+		return ERR_PTR(ret);
+	}
+
 	cell_entry = nvmem_find_cell_entry_by_node(nvmem, cell_np);
 	of_node_put(cell_np);
 	if (!cell_entry) {
 		__nvmem_device_put(nvmem);
-		return ERR_PTR(-ENOENT);
+		nvmem_layout_module_put(nvmem);
+		if (nvmem->layout)
+			return ERR_PTR(-EPROBE_DEFER);
+		else
+			return ERR_PTR(-ENOENT);
 	}
 
 	cell = nvmem_create_cell(cell_entry, id, cell_index);
-	if (IS_ERR(cell))
+	if (IS_ERR(cell)) {
 		__nvmem_device_put(nvmem);
+		nvmem_layout_module_put(nvmem);
+	}
 
 	return cell;
 }
@@ -1557,6 +1587,7 @@ void nvmem_cell_put(struct nvmem_cell *cell)
 
 	kfree(cell);
 	__nvmem_device_put(nvmem);
+	nvmem_layout_module_put(nvmem);
 }
 EXPORT_SYMBOL_GPL(nvmem_cell_put);
 
@@ -2132,13 +2163,37 @@ const char *nvmem_dev_name(struct nvmem_device *nvmem)
 }
 EXPORT_SYMBOL_GPL(nvmem_dev_name);
 
+/**
+ * nvmem_dev_size() - Get the size of a given nvmem device.
+ *
+ * @nvmem: nvmem device.
+ *
+ * Return: size of the nvmem device.
+ */
+size_t nvmem_dev_size(struct nvmem_device *nvmem)
+{
+	return nvmem->size;
+}
+EXPORT_SYMBOL_GPL(nvmem_dev_size);
+
 static int __init nvmem_init(void)
 {
-	return bus_register(&nvmem_bus_type);
+	int ret;
+
+	ret = bus_register(&nvmem_bus_type);
+	if (ret)
+		return ret;
+
+	ret = nvmem_layout_bus_register();
+	if (ret)
+		bus_unregister(&nvmem_bus_type);
+
+	return ret;
 }
 
 static void __exit nvmem_exit(void)
 {
+	nvmem_layout_bus_unregister();
 	bus_unregister(&nvmem_bus_type);
 }
 
diff --git a/drivers/nvmem/imx-ocotp.c b/drivers/nvmem/imx-ocotp.c
index f1e202efaa49..79dd4fda0329 100644
--- a/drivers/nvmem/imx-ocotp.c
+++ b/drivers/nvmem/imx-ocotp.c
@@ -583,17 +583,12 @@ static const struct of_device_id imx_ocotp_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, imx_ocotp_dt_ids);
 
-static void imx_ocotp_fixup_cell_info(struct nvmem_device *nvmem,
-				      struct nvmem_layout *layout,
-				      struct nvmem_cell_info *cell)
+static void imx_ocotp_fixup_dt_cell_info(struct nvmem_device *nvmem,
+					 struct nvmem_cell_info *cell)
 {
 	cell->read_post_process = imx_ocotp_cell_pp;
 }
 
-static struct nvmem_layout imx_ocotp_layout = {
-	.fixup_cell_info = imx_ocotp_fixup_cell_info,
-};
-
 static int imx_ocotp_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -619,7 +614,7 @@ static int imx_ocotp_probe(struct platform_device *pdev)
 	imx_ocotp_nvmem_config.size = 4 * priv->params->nregs;
 	imx_ocotp_nvmem_config.dev = dev;
 	imx_ocotp_nvmem_config.priv = priv;
-	imx_ocotp_nvmem_config.layout = &imx_ocotp_layout;
+	imx_ocotp_nvmem_config.fixup_dt_cell_info = &imx_ocotp_fixup_dt_cell_info;
 
 	priv->config = &imx_ocotp_nvmem_config;
 
diff --git a/drivers/nvmem/internals.h b/drivers/nvmem/internals.h
new file mode 100644
index 000000000000..18fed57270e5
--- /dev/null
+++ b/drivers/nvmem/internals.h
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _LINUX_NVMEM_INTERNALS_H
+#define _LINUX_NVMEM_INTERNALS_H
+
+#include <linux/device.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/nvmem-provider.h>
+
+struct nvmem_device {
+	struct module		*owner;
+	struct device		dev;
+	struct list_head	node;
+	int			stride;
+	int			word_size;
+	int			id;
+	struct kref		refcnt;
+	size_t			size;
+	bool			read_only;
+	bool			root_only;
+	int			flags;
+	enum nvmem_type		type;
+	struct bin_attribute	eeprom;
+	struct device		*base_dev;
+	struct list_head	cells;
+	void (*fixup_dt_cell_info)(struct nvmem_device *nvmem,
+				   struct nvmem_cell_info *cell);
+	const struct nvmem_keepout *keepout;
+	unsigned int		nkeepout;
+	nvmem_reg_read_t	reg_read;
+	nvmem_reg_write_t	reg_write;
+	struct gpio_desc	*wp_gpio;
+	struct nvmem_layout	*layout;
+	void *priv;
+	bool			sysfs_cells_populated;
+};
+
+#if IS_ENABLED(CONFIG_OF)
+int nvmem_layout_bus_register(void);
+void nvmem_layout_bus_unregister(void);
+int nvmem_populate_layout(struct nvmem_device *nvmem);
+void nvmem_destroy_layout(struct nvmem_device *nvmem);
+#else /* CONFIG_OF */
+static inline int nvmem_layout_bus_register(void)
+{
+	return 0;
+}
+
+static inline void nvmem_layout_bus_unregister(void) {}
+
+static inline int nvmem_populate_layout(struct nvmem_device *nvmem)
+{
+	return 0;
+}
+
+static inline void nvmem_destroy_layout(struct nvmem_device *nvmem) { }
+#endif /* CONFIG_OF */
+
+#endif  /* ifndef _LINUX_NVMEM_INTERNALS_H */
diff --git a/drivers/nvmem/layouts.c b/drivers/nvmem/layouts.c
new file mode 100644
index 000000000000..6a6aa58369ff
--- /dev/null
+++ b/drivers/nvmem/layouts.c
@@ -0,0 +1,201 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * NVMEM layout bus handling
+ *
+ * Copyright (C) 2023 Bootlin
+ * Author: Miquel Raynal <miquel.raynal@bootlin.com
+ */
+
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_irq.h>
+
+#include "internals.h"
+
+#define to_nvmem_layout_driver(drv) \
+	(container_of((drv), struct nvmem_layout_driver, driver))
+#define to_nvmem_layout_device(_dev) \
+	container_of((_dev), struct nvmem_layout, dev)
+
+static int nvmem_layout_bus_match(struct device *dev, struct device_driver *drv)
+{
+	return of_driver_match_device(dev, drv);
+}
+
+static int nvmem_layout_bus_probe(struct device *dev)
+{
+	struct nvmem_layout_driver *drv = to_nvmem_layout_driver(dev->driver);
+	struct nvmem_layout *layout = to_nvmem_layout_device(dev);
+
+	if (!drv->probe || !drv->remove)
+		return -EINVAL;
+
+	return drv->probe(layout);
+}
+
+static void nvmem_layout_bus_remove(struct device *dev)
+{
+	struct nvmem_layout_driver *drv = to_nvmem_layout_driver(dev->driver);
+	struct nvmem_layout *layout = to_nvmem_layout_device(dev);
+
+	return drv->remove(layout);
+}
+
+static struct bus_type nvmem_layout_bus_type = {
+	.name		= "nvmem-layout",
+	.match		= nvmem_layout_bus_match,
+	.probe		= nvmem_layout_bus_probe,
+	.remove		= nvmem_layout_bus_remove,
+};
+
+int nvmem_layout_driver_register(struct nvmem_layout_driver *drv)
+{
+	drv->driver.bus = &nvmem_layout_bus_type;
+
+	return driver_register(&drv->driver);
+}
+EXPORT_SYMBOL_GPL(nvmem_layout_driver_register);
+
+void nvmem_layout_driver_unregister(struct nvmem_layout_driver *drv)
+{
+	driver_unregister(&drv->driver);
+}
+EXPORT_SYMBOL_GPL(nvmem_layout_driver_unregister);
+
+static void nvmem_layout_release_device(struct device *dev)
+{
+	struct nvmem_layout *layout = to_nvmem_layout_device(dev);
+
+	of_node_put(layout->dev.of_node);
+	kfree(layout);
+}
+
+static int nvmem_layout_create_device(struct nvmem_device *nvmem,
+				      struct device_node *np)
+{
+	struct nvmem_layout *layout;
+	struct device *dev;
+	int ret;
+
+	layout = kzalloc(sizeof(*layout), GFP_KERNEL);
+	if (!layout)
+		return -ENOMEM;
+
+	/* Create a bidirectional link */
+	layout->nvmem = nvmem;
+	nvmem->layout = layout;
+
+	/* Device model registration */
+	dev = &layout->dev;
+	device_initialize(dev);
+	dev->parent = &nvmem->dev;
+	dev->bus = &nvmem_layout_bus_type;
+	dev->release = nvmem_layout_release_device;
+	dev->coherent_dma_mask = DMA_BIT_MASK(32);
+	dev->dma_mask = &dev->coherent_dma_mask;
+	device_set_node(dev, of_fwnode_handle(of_node_get(np)));
+	of_device_make_bus_id(dev);
+	of_msi_configure(dev, dev->of_node);
+
+	ret = device_add(dev);
+	if (ret) {
+		put_device(dev);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id of_nvmem_layout_skip_table[] = {
+	{ .compatible = "fixed-layout", },
+	{}
+};
+
+static int nvmem_layout_bus_populate(struct nvmem_device *nvmem,
+				     struct device_node *layout_dn)
+{
+	int ret;
+
+	/* Make sure it has a compatible property */
+	if (!of_get_property(layout_dn, "compatible", NULL)) {
+		pr_debug("%s() - skipping %pOF, no compatible prop\n",
+			 __func__, layout_dn);
+		return 0;
+	}
+
+	/* Fixed layouts are parsed manually somewhere else for now */
+	if (of_match_node(of_nvmem_layout_skip_table, layout_dn)) {
+		pr_debug("%s() - skipping %pOF node\n", __func__, layout_dn);
+		return 0;
+	}
+
+	if (of_node_check_flag(layout_dn, OF_POPULATED_BUS)) {
+		pr_debug("%s() - skipping %pOF, already populated\n",
+			 __func__, layout_dn);
+
+		return 0;
+	}
+
+	/* NVMEM layout buses expect only a single device representing the layout */
+	ret = nvmem_layout_create_device(nvmem, layout_dn);
+	if (ret)
+		return ret;
+
+	of_node_set_flag(layout_dn, OF_POPULATED_BUS);
+
+	return 0;
+}
+
+struct device_node *of_nvmem_layout_get_container(struct nvmem_device *nvmem)
+{
+	return of_get_child_by_name(nvmem->dev.of_node, "nvmem-layout");
+}
+EXPORT_SYMBOL_GPL(of_nvmem_layout_get_container);
+
+/*
+ * Returns the number of devices populated, 0 if the operation was not relevant
+ * for this nvmem device, an error code otherwise.
+ */
+int nvmem_populate_layout(struct nvmem_device *nvmem)
+{
+	struct device_node *layout_dn;
+	int ret;
+
+	layout_dn = of_nvmem_layout_get_container(nvmem);
+	if (!layout_dn)
+		return 0;
+
+	/* Populate the layout device */
+	device_links_supplier_sync_state_pause();
+	ret = nvmem_layout_bus_populate(nvmem, layout_dn);
+	device_links_supplier_sync_state_resume();
+
+	of_node_put(layout_dn);
+	return ret;
+}
+
+void nvmem_destroy_layout(struct nvmem_device *nvmem)
+{
+	struct device *dev;
+
+	if (!nvmem->layout)
+		return;
+
+	dev = &nvmem->layout->dev;
+	of_node_clear_flag(dev->of_node, OF_POPULATED_BUS);
+	device_unregister(dev);
+}
+
+int nvmem_layout_bus_register(void)
+{
+	return bus_register(&nvmem_layout_bus_type);
+}
+
+void nvmem_layout_bus_unregister(void)
+{
+	bus_unregister(&nvmem_layout_bus_type);
+}
diff --git a/drivers/nvmem/layouts/Kconfig b/drivers/nvmem/layouts/Kconfig
index 7ff1ee1c1f05..9c6e672fc350 100644
--- a/drivers/nvmem/layouts/Kconfig
+++ b/drivers/nvmem/layouts/Kconfig
@@ -1,5 +1,11 @@
 # SPDX-License-Identifier: GPL-2.0
 
+config NVMEM_LAYOUTS
+	bool
+	depends on OF
+
+if NVMEM_LAYOUTS
+
 menu "Layout Types"
 
 config NVMEM_LAYOUT_SL28_VPD
@@ -21,3 +27,5 @@ config NVMEM_LAYOUT_ONIE_TLV
 	  If unsure, say N.
 
 endmenu
+
+endif
diff --git a/drivers/nvmem/layouts/onie-tlv.c b/drivers/nvmem/layouts/onie-tlv.c
index 59fc87ccfcff..9d2ad5f2dc10 100644
--- a/drivers/nvmem/layouts/onie-tlv.c
+++ b/drivers/nvmem/layouts/onie-tlv.c
@@ -182,9 +182,10 @@ static bool onie_tlv_crc_is_valid(struct device *dev, size_t table_len, u8 *tabl
 	return true;
 }
 
-static int onie_tlv_parse_table(struct device *dev, struct nvmem_device *nvmem,
-				struct nvmem_layout *layout)
+static int onie_tlv_parse_table(struct nvmem_layout *layout)
 {
+	struct nvmem_device *nvmem = layout->nvmem;
+	struct device *dev = &layout->dev;
 	struct onie_tlv_hdr hdr;
 	size_t table_len, data_len, hdr_len;
 	u8 *table, *data;
@@ -226,16 +227,32 @@ static int onie_tlv_parse_table(struct device *dev, struct nvmem_device *nvmem,
 	return 0;
 }
 
+static int onie_tlv_probe(struct nvmem_layout *layout)
+{
+	layout->add_cells = onie_tlv_parse_table;
+
+	return nvmem_layout_register(layout);
+}
+
+static void onie_tlv_remove(struct nvmem_layout *layout)
+{
+	nvmem_layout_unregister(layout);
+}
+
 static const struct of_device_id onie_tlv_of_match_table[] = {
 	{ .compatible = "onie,tlv-layout", },
 	{},
 };
 MODULE_DEVICE_TABLE(of, onie_tlv_of_match_table);
 
-static struct nvmem_layout onie_tlv_layout = {
-	.name = "ONIE tlv layout",
-	.of_match_table = onie_tlv_of_match_table,
-	.add_cells = onie_tlv_parse_table,
+static struct nvmem_layout_driver onie_tlv_layout = {
+	.driver = {
+		.owner = THIS_MODULE,
+		.name = "onie-tlv-layout",
+		.of_match_table = onie_tlv_of_match_table,
+	},
+	.probe = onie_tlv_probe,
+	.remove = onie_tlv_remove,
 };
 module_nvmem_layout_driver(onie_tlv_layout);
 
diff --git a/drivers/nvmem/layouts/sl28vpd.c b/drivers/nvmem/layouts/sl28vpd.c
index 05671371f631..53fa50f17dca 100644
--- a/drivers/nvmem/layouts/sl28vpd.c
+++ b/drivers/nvmem/layouts/sl28vpd.c
@@ -80,9 +80,10 @@ static int sl28vpd_v1_check_crc(struct device *dev, struct nvmem_device *nvmem)
 	return 0;
 }
 
-static int sl28vpd_add_cells(struct device *dev, struct nvmem_device *nvmem,
-			     struct nvmem_layout *layout)
+static int sl28vpd_add_cells(struct nvmem_layout *layout)
 {
+	struct nvmem_device *nvmem = layout->nvmem;
+	struct device *dev = &layout->dev;
 	const struct nvmem_cell_info *pinfo;
 	struct nvmem_cell_info info = {0};
 	struct device_node *layout_np;
@@ -135,16 +136,32 @@ static int sl28vpd_add_cells(struct device *dev, struct nvmem_device *nvmem,
 	return 0;
 }
 
+static int sl28vpd_probe(struct nvmem_layout *layout)
+{
+	layout->add_cells = sl28vpd_add_cells;
+
+	return nvmem_layout_register(layout);
+}
+
+static void sl28vpd_remove(struct nvmem_layout *layout)
+{
+	nvmem_layout_unregister(layout);
+}
+
 static const struct of_device_id sl28vpd_of_match_table[] = {
 	{ .compatible = "kontron,sl28-vpd" },
 	{},
 };
 MODULE_DEVICE_TABLE(of, sl28vpd_of_match_table);
 
-static struct nvmem_layout sl28vpd_layout = {
-	.name = "sl28-vpd",
-	.of_match_table = sl28vpd_of_match_table,
-	.add_cells = sl28vpd_add_cells,
+static struct nvmem_layout_driver sl28vpd_layout = {
+	.driver = {
+		.owner = THIS_MODULE,
+		.name = "kontron-sl28vpd-layout",
+		.of_match_table = sl28vpd_of_match_table,
+	},
+	.probe = sl28vpd_probe,
+	.remove = sl28vpd_remove,
 };
 module_nvmem_layout_driver(sl28vpd_layout);
 
diff --git a/drivers/nvmem/mtk-efuse.c b/drivers/nvmem/mtk-efuse.c
index 87c94686cfd2..84f05b40a411 100644
--- a/drivers/nvmem/mtk-efuse.c
+++ b/drivers/nvmem/mtk-efuse.c
@@ -45,9 +45,8 @@ static int mtk_efuse_gpu_speedbin_pp(void *context, const char *id, int index,
 	return 0;
 }
 
-static void mtk_efuse_fixup_cell_info(struct nvmem_device *nvmem,
-				      struct nvmem_layout *layout,
-				      struct nvmem_cell_info *cell)
+static void mtk_efuse_fixup_dt_cell_info(struct nvmem_device *nvmem,
+					 struct nvmem_cell_info *cell)
 {
 	size_t sz = strlen(cell->name);
 
@@ -61,10 +60,6 @@ static void mtk_efuse_fixup_cell_info(struct nvmem_device *nvmem,
 		cell->read_post_process = mtk_efuse_gpu_speedbin_pp;
 }
 
-static struct nvmem_layout mtk_efuse_layout = {
-	.fixup_cell_info = mtk_efuse_fixup_cell_info,
-};
-
 static int mtk_efuse_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -91,7 +86,7 @@ static int mtk_efuse_probe(struct platform_device *pdev)
 	econfig.priv = priv;
 	econfig.dev = dev;
 	if (pdata->uses_post_processing)
-		econfig.layout = &mtk_efuse_layout;
+		econfig.fixup_dt_cell_info = &mtk_efuse_fixup_dt_cell_info;
 	nvmem = devm_nvmem_register(dev, &econfig);
 
 	return PTR_ERR_OR_ZERO(nvmem);
diff --git a/drivers/nvmem/stm32-romem.c b/drivers/nvmem/stm32-romem.c
index 8a553b1799a8..82879b1c9eb9 100644
--- a/drivers/nvmem/stm32-romem.c
+++ b/drivers/nvmem/stm32-romem.c
@@ -269,6 +269,19 @@ static const struct stm32_romem_cfg stm32mp13_bsec_cfg = {
 	.ta = true,
 };
 
+/*
+ * STM32MP25 BSEC OTP: 3 regions of 32-bits data words
+ *   lower OTP (OTP0 to OTP127), bitwise (1-bit) programmable
+ *   mid OTP (OTP128 to OTP255), bulk (32-bit) programmable
+ *   upper OTP (OTP256 to OTP383), bulk (32-bit) programmable
+ *              but no access to HWKEY and ECIES key: limited at OTP367
+ */
+static const struct stm32_romem_cfg stm32mp25_bsec_cfg = {
+	.size = 368 * 4,
+	.lower = 127,
+	.ta = true,
+};
+
 static const struct of_device_id stm32_romem_of_match[] __maybe_unused = {
 	{ .compatible = "st,stm32f4-otp", }, {
 		.compatible = "st,stm32mp15-bsec",
@@ -276,6 +289,9 @@ static const struct of_device_id stm32_romem_of_match[] __maybe_unused = {
 	}, {
 		.compatible = "st,stm32mp13-bsec",
 		.data = (void *)&stm32mp13_bsec_cfg,
+	}, {
+		.compatible = "st,stm32mp25-bsec",
+		.data = (void *)&stm32mp25_bsec_cfg,
 	},
 	{ /* sentinel */ },
 };
diff --git a/drivers/nvmem/u-boot-env.c b/drivers/nvmem/u-boot-env.c
index c4ae94af4af7..befbab156cda 100644
--- a/drivers/nvmem/u-boot-env.c
+++ b/drivers/nvmem/u-boot-env.c
@@ -23,13 +23,10 @@ enum u_boot_env_format {
 
 struct u_boot_env {
 	struct device *dev;
+	struct nvmem_device *nvmem;
 	enum u_boot_env_format format;
 
 	struct mtd_info *mtd;
-
-	/* Cells */
-	struct nvmem_cell_info *cells;
-	int ncells;
 };
 
 struct u_boot_env_image_single {
@@ -94,70 +91,71 @@ static int u_boot_env_read_post_process_ethaddr(void *context, const char *id, i
 static int u_boot_env_add_cells(struct u_boot_env *priv, uint8_t *buf,
 				size_t data_offset, size_t data_len)
 {
+	struct nvmem_device *nvmem = priv->nvmem;
 	struct device *dev = priv->dev;
 	char *data = buf + data_offset;
 	char *var, *value, *eq;
-	int idx;
-
-	priv->ncells = 0;
-	for (var = data; var < data + data_len && *var; var += strlen(var) + 1)
-		priv->ncells++;
-
-	priv->cells = devm_kcalloc(dev, priv->ncells, sizeof(*priv->cells), GFP_KERNEL);
-	if (!priv->cells)
-		return -ENOMEM;
 
-	for (var = data, idx = 0;
+	for (var = data;
 	     var < data + data_len && *var;
-	     var = value + strlen(value) + 1, idx++) {
+	     var = value + strlen(value) + 1) {
+		struct nvmem_cell_info info = {};
+
 		eq = strchr(var, '=');
 		if (!eq)
 			break;
 		*eq = '\0';
 		value = eq + 1;
 
-		priv->cells[idx].name = devm_kstrdup(dev, var, GFP_KERNEL);
-		if (!priv->cells[idx].name)
+		info.name = devm_kstrdup(dev, var, GFP_KERNEL);
+		if (!info.name)
 			return -ENOMEM;
-		priv->cells[idx].offset = data_offset + value - data;
-		priv->cells[idx].bytes = strlen(value);
-		priv->cells[idx].np = of_get_child_by_name(dev->of_node, priv->cells[idx].name);
+		info.offset = data_offset + value - data;
+		info.bytes = strlen(value);
+		info.np = of_get_child_by_name(dev->of_node, info.name);
 		if (!strcmp(var, "ethaddr")) {
-			priv->cells[idx].raw_len = strlen(value);
-			priv->cells[idx].bytes = ETH_ALEN;
-			priv->cells[idx].read_post_process = u_boot_env_read_post_process_ethaddr;
+			info.raw_len = strlen(value);
+			info.bytes = ETH_ALEN;
+			info.read_post_process = u_boot_env_read_post_process_ethaddr;
 		}
-	}
 
-	if (WARN_ON(idx != priv->ncells))
-		priv->ncells = idx;
+		nvmem_add_one_cell(nvmem, &info);
+	}
 
 	return 0;
 }
 
 static int u_boot_env_parse(struct u_boot_env *priv)
 {
+	struct nvmem_device *nvmem = priv->nvmem;
 	struct device *dev = priv->dev;
 	size_t crc32_data_offset;
 	size_t crc32_data_len;
 	size_t crc32_offset;
+	__le32 *crc32_addr;
 	size_t data_offset;
 	size_t data_len;
+	size_t dev_size;
 	uint32_t crc32;
 	uint32_t calc;
-	size_t bytes;
 	uint8_t *buf;
+	int bytes;
 	int err;
 
-	buf = kcalloc(1, priv->mtd->size, GFP_KERNEL);
+	dev_size = nvmem_dev_size(nvmem);
+
+	buf = kzalloc(dev_size, GFP_KERNEL);
 	if (!buf) {
 		err = -ENOMEM;
 		goto err_out;
 	}
 
-	err = mtd_read(priv->mtd, 0, priv->mtd->size, &bytes, buf);
-	if ((err && !mtd_is_bitflip(err)) || bytes != priv->mtd->size) {
-		dev_err(dev, "Failed to read from mtd: %d\n", err);
+	bytes = nvmem_device_read(nvmem, 0, dev_size, buf);
+	if (bytes < 0) {
+		err = bytes;
+		goto err_kfree;
+	} else if (bytes != dev_size) {
+		err = -EIO;
 		goto err_kfree;
 	}
 
@@ -178,9 +176,10 @@ static int u_boot_env_parse(struct u_boot_env *priv)
 		data_offset = offsetof(struct u_boot_env_image_broadcom, data);
 		break;
 	}
-	crc32 = le32_to_cpu(*(__le32 *)(buf + crc32_offset));
-	crc32_data_len = priv->mtd->size - crc32_data_offset;
-	data_len = priv->mtd->size - data_offset;
+	crc32_addr = (__le32 *)(buf + crc32_offset);
+	crc32 = le32_to_cpu(*crc32_addr);
+	crc32_data_len = dev_size - crc32_data_offset;
+	data_len = dev_size - data_offset;
 
 	calc = crc32(~0, buf + crc32_data_offset, crc32_data_len) ^ ~0L;
 	if (calc != crc32) {
@@ -189,10 +188,8 @@ static int u_boot_env_parse(struct u_boot_env *priv)
 		goto err_kfree;
 	}
 
-	buf[priv->mtd->size - 1] = '\0';
+	buf[dev_size - 1] = '\0';
 	err = u_boot_env_add_cells(priv, buf, data_offset, data_len);
-	if (err)
-		dev_err(dev, "Failed to add cells: %d\n", err);
 
 err_kfree:
 	kfree(buf);
@@ -209,7 +206,6 @@ static int u_boot_env_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct device_node *np = dev->of_node;
 	struct u_boot_env *priv;
-	int err;
 
 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 	if (!priv)
@@ -224,17 +220,15 @@ static int u_boot_env_probe(struct platform_device *pdev)
 		return PTR_ERR(priv->mtd);
 	}
 
-	err = u_boot_env_parse(priv);
-	if (err)
-		return err;
-
 	config.dev = dev;
-	config.cells = priv->cells;
-	config.ncells = priv->ncells;
 	config.priv = priv;
 	config.size = priv->mtd->size;
 
-	return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
+	priv->nvmem = devm_nvmem_register(dev, &config);
+	if (IS_ERR(priv->nvmem))
+		return PTR_ERR(priv->nvmem);
+
+	return u_boot_env_parse(priv);
 }
 
 static const struct of_device_id u_boot_env_of_match_table[] = {