kernel: backport U-Boot environment data NVMEM driver

It parses U-Boot env data into NVMEM cells.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

8 files changed, 708 insertions, 8 deletions

diff --git a/target/linux/generic/backport-5.10/414-v6.1-mtd-allow-getting-MTD-device-associated-with-a-speci.patch b/target/linux/generic/backport-5.10/414-v6.1-mtd-allow-getting-MTD-device-associated-with-a-speci.patch
new file mode 100644
index 0000000000..0e8708e5bb
--- /dev/null
+++ b/target/linux/generic/backport-5.10/414-v6.1-mtd-allow-getting-MTD-device-associated-with-a-speci.patch
@@ -0,0 +1,72 @@
+From b0321721be50b80c03a51866a94fde4f94690e18 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
+Date: Wed, 15 Jun 2022 21:42:59 +0200
+Subject: [PATCH] mtd: allow getting MTD device associated with a specific DT
+ node
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+MTD subsystem API allows interacting with MTD devices (e.g. reading,
+writing, handling bad blocks). So far a random driver could get MTD
+device only by its name (get_mtd_device_nm()). This change allows
+getting them also by a DT node.
+
+This API is required for drivers handling DT defined MTD partitions in a
+specific way (e.g. U-Boot (sub)partition with environment variables).
+
+Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
+Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>
+Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
+---
+ drivers/mtd/mtdcore.c   | 28 ++++++++++++++++++++++++++++
+ include/linux/mtd/mtd.h |  1 +
+ 2 files changed, 29 insertions(+)
+
+--- a/drivers/mtd/mtdcore.c
++++ b/drivers/mtd/mtdcore.c
+@@ -1070,6 +1070,34 @@ int __get_mtd_device(struct mtd_info *mt
+ EXPORT_SYMBOL_GPL(__get_mtd_device);
+ 
+ /**
++ * of_get_mtd_device_by_node - obtain an MTD device associated with a given node
++ *
++ * @np: device tree node
++ */
++struct mtd_info *of_get_mtd_device_by_node(struct device_node *np)
++{
++	struct mtd_info *mtd = NULL;
++	struct mtd_info *tmp;
++	int err;
++
++	mutex_lock(&mtd_table_mutex);
++
++	err = -EPROBE_DEFER;
++	mtd_for_each_device(tmp) {
++		if (mtd_get_of_node(tmp) == np) {
++			mtd = tmp;
++			err = __get_mtd_device(mtd);
++			break;
++		}
++	}
++
++	mutex_unlock(&mtd_table_mutex);
++
++	return err ? ERR_PTR(err) : mtd;
++}
++EXPORT_SYMBOL_GPL(of_get_mtd_device_by_node);
++
++/**
+  *	get_mtd_device_nm - obtain a validated handle for an MTD device by
+  *	device name
+  *	@name: MTD device name to open
+--- a/include/linux/mtd/mtd.h
++++ b/include/linux/mtd/mtd.h
+@@ -675,6 +675,7 @@ extern int mtd_device_unregister(struct
+ 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);
++extern struct mtd_info *of_get_mtd_device_by_node(struct device_node *np);
+ extern struct mtd_info *get_mtd_device_nm(const char *name);
+ extern void put_mtd_device(struct mtd_info *mtd);
+ 
diff --git a/target/linux/generic/backport-5.10/801-v6.1-nvmem-add-driver-handling-U-Boot-environment-variabl.patch b/target/linux/generic/backport-5.10/801-v6.1-nvmem-add-driver-handling-U-Boot-environment-variabl.patch
new file mode 100644
index 0000000000..1459d1184e
--- /dev/null
+++ b/target/linux/generic/backport-5.10/801-v6.1-nvmem-add-driver-handling-U-Boot-environment-variabl.patch
@@ -0,0 +1,278 @@
+From f955dc14450695564926711cf9fa8e1d5d854302 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
+Date: Wed, 15 Jun 2022 21:43:00 +0200
+Subject: [PATCH] nvmem: add driver handling U-Boot environment variables
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+U-Boot stores its setup as environment variables. It's a list of
+key-value pairs stored on flash device with a custom header.
+
+This commit adds an NVMEM driver that:
+1. Provides NVMEM access to environment vars binary data
+2. Extracts variables as NVMEM cells
+
+Current Linux's NVMEM sysfs API allows reading whole NVMEM data block.
+It can be used by user-space tools for reading U-Boot env vars block
+without the hassle of finding its location. Parsing will still need to
+be re-done there.
+
+Kernel-parsed NVMEM cells can be read however by Linux drivers. This may
+be useful for Ethernet drivers for reading device MAC address which is
+often stored as U-Boot env variable.
+
+Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
+Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
+Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
+---
+
+--- a/drivers/nvmem/Kconfig
++++ b/drivers/nvmem/Kconfig
+@@ -270,4 +270,17 @@ config SPRD_EFUSE
+ 	  This driver can also be built as a module. If so, the module
+ 	  will be called nvmem-sprd-efuse.
+ 
++config NVMEM_U_BOOT_ENV
++	tristate "U-Boot environment variables support"
++	depends on OF && MTD
++	select CRC32
++	help
++	  U-Boot stores its setup as environment variables. This driver adds
++	  support for verifying & exporting such data. It also exposes variables
++	  as NVMEM cells so they can be referenced by other drivers.
++
++	  Currently this drivers works only with env variables on top of MTD.
++
++	  If compiled as module it will be called nvmem_u-boot-env.
++
+ endif
+--- a/drivers/nvmem/Makefile
++++ b/drivers/nvmem/Makefile
+@@ -55,3 +55,5 @@ obj-$(CONFIG_NVMEM_ZYNQMP)	+= nvmem_zynq
+ nvmem_zynqmp_nvmem-y		:= zynqmp_nvmem.o
+ obj-$(CONFIG_SPRD_EFUSE)	+= nvmem_sprd_efuse.o
+ nvmem_sprd_efuse-y		:= sprd-efuse.o
++obj-$(CONFIG_NVMEM_U_BOOT_ENV)	+= nvmem_u-boot-env.o
++nvmem_u-boot-env-y		:= u-boot-env.o
+--- /dev/null
++++ b/drivers/nvmem/u-boot-env.c
+@@ -0,0 +1,218 @@
++// SPDX-License-Identifier: GPL-2.0-only
++/*
++ * Copyright (C) 2022 Rafał Miłecki <rafal@milecki.pl>
++ */
++
++#include <linux/crc32.h>
++#include <linux/mod_devicetable.h>
++#include <linux/module.h>
++#include <linux/mtd/mtd.h>
++#include <linux/nvmem-consumer.h>
++#include <linux/nvmem-provider.h>
++#include <linux/of_device.h>
++#include <linux/platform_device.h>
++#include <linux/slab.h>
++
++enum u_boot_env_format {
++	U_BOOT_FORMAT_SINGLE,
++	U_BOOT_FORMAT_REDUNDANT,
++};
++
++struct u_boot_env {
++	struct device *dev;
++	enum u_boot_env_format format;
++
++	struct mtd_info *mtd;
++
++	/* Cells */
++	struct nvmem_cell_info *cells;
++	int ncells;
++};
++
++struct u_boot_env_image_single {
++	__le32 crc32;
++	uint8_t data[];
++} __packed;
++
++struct u_boot_env_image_redundant {
++	__le32 crc32;
++	u8 mark;
++	uint8_t data[];
++} __packed;
++
++static int u_boot_env_read(void *context, unsigned int offset, void *val,
++			   size_t bytes)
++{
++	struct u_boot_env *priv = context;
++	struct device *dev = priv->dev;
++	size_t bytes_read;
++	int err;
++
++	err = mtd_read(priv->mtd, offset, bytes, &bytes_read, val);
++	if (err && !mtd_is_bitflip(err)) {
++		dev_err(dev, "Failed to read from mtd: %d\n", err);
++		return err;
++	}
++
++	if (bytes_read != bytes) {
++		dev_err(dev, "Failed to read %zu bytes\n", bytes);
++		return -EIO;
++	}
++
++	return 0;
++}
++
++static int u_boot_env_add_cells(struct u_boot_env *priv, uint8_t *buf,
++				size_t data_offset, size_t data_len)
++{
++	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;
++	     var < data + data_len && *var;
++	     var = value + strlen(value) + 1, idx++) {
++		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)
++			return -ENOMEM;
++		priv->cells[idx].offset = data_offset + value - data;
++		priv->cells[idx].bytes = strlen(value);
++	}
++
++	if (WARN_ON(idx != priv->ncells))
++		priv->ncells = idx;
++
++	return 0;
++}
++
++static int u_boot_env_parse(struct u_boot_env *priv)
++{
++	struct device *dev = priv->dev;
++	size_t crc32_data_offset;
++	size_t crc32_data_len;
++	size_t crc32_offset;
++	size_t data_offset;
++	size_t data_len;
++	uint32_t crc32;
++	uint32_t calc;
++	size_t bytes;
++	uint8_t *buf;
++	int err;
++
++	buf = kcalloc(1, priv->mtd->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);
++		goto err_kfree;
++	}
++
++	switch (priv->format) {
++	case U_BOOT_FORMAT_SINGLE:
++		crc32_offset = offsetof(struct u_boot_env_image_single, crc32);
++		crc32_data_offset = offsetof(struct u_boot_env_image_single, data);
++		data_offset = offsetof(struct u_boot_env_image_single, data);
++		break;
++	case U_BOOT_FORMAT_REDUNDANT:
++		crc32_offset = offsetof(struct u_boot_env_image_redundant, crc32);
++		crc32_data_offset = offsetof(struct u_boot_env_image_redundant, mark);
++		data_offset = offsetof(struct u_boot_env_image_redundant, data);
++		break;
++	}
++	crc32 = le32_to_cpu(*(uint32_t *)(buf + crc32_offset));
++	crc32_data_len = priv->mtd->size - crc32_data_offset;
++	data_len = priv->mtd->size - data_offset;
++
++	calc = crc32(~0, buf + crc32_data_offset, crc32_data_len) ^ ~0L;
++	if (calc != crc32) {
++		dev_err(dev, "Invalid calculated CRC32: 0x%08x (expected: 0x%08x)\n", calc, crc32);
++		err = -EINVAL;
++		goto err_kfree;
++	}
++
++	buf[priv->mtd->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);
++err_out:
++	return err;
++}
++
++static int u_boot_env_probe(struct platform_device *pdev)
++{
++	struct nvmem_config config = {
++		.name = "u-boot-env",
++		.reg_read = u_boot_env_read,
++	};
++	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)
++		return -ENOMEM;
++	priv->dev = dev;
++
++	priv->format = (uintptr_t)of_device_get_match_data(dev);
++
++	priv->mtd = of_get_mtd_device_by_node(np);
++	if (IS_ERR(priv->mtd)) {
++		dev_err_probe(dev, PTR_ERR(priv->mtd), "Failed to get %pOF MTD\n", np);
++		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));
++}
++
++static const struct of_device_id u_boot_env_of_match_table[] = {
++	{ .compatible = "u-boot,env", .data = (void *)U_BOOT_FORMAT_SINGLE, },
++	{ .compatible = "u-boot,env-redundant-bool", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
++	{ .compatible = "u-boot,env-redundant-count", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
++	{},
++};
++
++static struct platform_driver u_boot_env_driver = {
++	.probe = u_boot_env_probe,
++	.driver = {
++		.name = "u_boot_env",
++		.of_match_table = u_boot_env_of_match_table,
++	},
++};
++module_platform_driver(u_boot_env_driver);
++
++MODULE_AUTHOR("Rafał Miłecki");
++MODULE_LICENSE("GPL");
++MODULE_DEVICE_TABLE(of, u_boot_env_of_match_table);
diff --git a/target/linux/generic/backport-5.15/403-v6.1-mtd-allow-getting-MTD-device-associated-with-a-speci.patch b/target/linux/generic/backport-5.15/403-v6.1-mtd-allow-getting-MTD-device-associated-with-a-speci.patch
new file mode 100644
index 0000000000..be1aa9cfb8
--- /dev/null
+++ b/target/linux/generic/backport-5.15/403-v6.1-mtd-allow-getting-MTD-device-associated-with-a-speci.patch
@@ -0,0 +1,72 @@
+From b0321721be50b80c03a51866a94fde4f94690e18 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
+Date: Wed, 15 Jun 2022 21:42:59 +0200
+Subject: [PATCH] mtd: allow getting MTD device associated with a specific DT
+ node
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+MTD subsystem API allows interacting with MTD devices (e.g. reading,
+writing, handling bad blocks). So far a random driver could get MTD
+device only by its name (get_mtd_device_nm()). This change allows
+getting them also by a DT node.
+
+This API is required for drivers handling DT defined MTD partitions in a
+specific way (e.g. U-Boot (sub)partition with environment variables).
+
+Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
+Acked-by: Miquel Raynal <miquel.raynal@bootlin.com>
+Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
+---
+ drivers/mtd/mtdcore.c   | 28 ++++++++++++++++++++++++++++
+ include/linux/mtd/mtd.h |  1 +
+ 2 files changed, 29 insertions(+)
+
+--- a/drivers/mtd/mtdcore.c
++++ b/drivers/mtd/mtdcore.c
+@@ -1227,6 +1227,34 @@ int __get_mtd_device(struct mtd_info *mt
+ EXPORT_SYMBOL_GPL(__get_mtd_device);
+ 
+ /**
++ * of_get_mtd_device_by_node - obtain an MTD device associated with a given node
++ *
++ * @np: device tree node
++ */
++struct mtd_info *of_get_mtd_device_by_node(struct device_node *np)
++{
++	struct mtd_info *mtd = NULL;
++	struct mtd_info *tmp;
++	int err;
++
++	mutex_lock(&mtd_table_mutex);
++
++	err = -EPROBE_DEFER;
++	mtd_for_each_device(tmp) {
++		if (mtd_get_of_node(tmp) == np) {
++			mtd = tmp;
++			err = __get_mtd_device(mtd);
++			break;
++		}
++	}
++
++	mutex_unlock(&mtd_table_mutex);
++
++	return err ? ERR_PTR(err) : mtd;
++}
++EXPORT_SYMBOL_GPL(of_get_mtd_device_by_node);
++
++/**
+  *	get_mtd_device_nm - obtain a validated handle for an MTD device by
+  *	device name
+  *	@name: MTD device name to open
+--- a/include/linux/mtd/mtd.h
++++ b/include/linux/mtd/mtd.h
+@@ -682,6 +682,7 @@ extern int mtd_device_unregister(struct
+ 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);
++extern struct mtd_info *of_get_mtd_device_by_node(struct device_node *np);
+ extern struct mtd_info *get_mtd_device_nm(const char *name);
+ extern void put_mtd_device(struct mtd_info *mtd);
+ 
diff --git a/target/linux/generic/backport-5.15/802-v6.1-nvmem-add-driver-handling-U-Boot-environment-variabl.patch b/target/linux/generic/backport-5.15/802-v6.1-nvmem-add-driver-handling-U-Boot-environment-variabl.patch
new file mode 100644
index 0000000000..a40c61f929
--- /dev/null
+++ b/target/linux/generic/backport-5.15/802-v6.1-nvmem-add-driver-handling-U-Boot-environment-variabl.patch
@@ -0,0 +1,278 @@
+From f955dc14450695564926711cf9fa8e1d5d854302 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
+Date: Wed, 15 Jun 2022 21:43:00 +0200
+Subject: [PATCH] nvmem: add driver handling U-Boot environment variables
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+U-Boot stores its setup as environment variables. It's a list of
+key-value pairs stored on flash device with a custom header.
+
+This commit adds an NVMEM driver that:
+1. Provides NVMEM access to environment vars binary data
+2. Extracts variables as NVMEM cells
+
+Current Linux's NVMEM sysfs API allows reading whole NVMEM data block.
+It can be used by user-space tools for reading U-Boot env vars block
+without the hassle of finding its location. Parsing will still need to
+be re-done there.
+
+Kernel-parsed NVMEM cells can be read however by Linux drivers. This may
+be useful for Ethernet drivers for reading device MAC address which is
+often stored as U-Boot env variable.
+
+Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
+Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
+Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
+---
+
+--- a/drivers/nvmem/Kconfig
++++ b/drivers/nvmem/Kconfig
+@@ -300,4 +300,17 @@ config NVMEM_BRCM_NVRAM
+ 	  This driver provides support for Broadcom's NVRAM that can be accessed
+ 	  using I/O mapping.
+ 
++config NVMEM_U_BOOT_ENV
++	tristate "U-Boot environment variables support"
++	depends on OF && MTD
++	select CRC32
++	help
++	  U-Boot stores its setup as environment variables. This driver adds
++	  support for verifying & exporting such data. It also exposes variables
++	  as NVMEM cells so they can be referenced by other drivers.
++
++	  Currently this drivers works only with env variables on top of MTD.
++
++	  If compiled as module it will be called nvmem_u-boot-env.
++
+ endif
+--- a/drivers/nvmem/Makefile
++++ b/drivers/nvmem/Makefile
+@@ -61,3 +61,5 @@ obj-$(CONFIG_NVMEM_RMEM) 	+= nvmem-rmem.
+ nvmem-rmem-y			:= rmem.o
+ obj-$(CONFIG_NVMEM_BRCM_NVRAM)	+= nvmem_brcm_nvram.o
+ nvmem_brcm_nvram-y		:= brcm_nvram.o
++obj-$(CONFIG_NVMEM_U_BOOT_ENV)	+= nvmem_u-boot-env.o
++nvmem_u-boot-env-y		:= u-boot-env.o
+--- /dev/null
++++ b/drivers/nvmem/u-boot-env.c
+@@ -0,0 +1,218 @@
++// SPDX-License-Identifier: GPL-2.0-only
++/*
++ * Copyright (C) 2022 Rafał Miłecki <rafal@milecki.pl>
++ */
++
++#include <linux/crc32.h>
++#include <linux/mod_devicetable.h>
++#include <linux/module.h>
++#include <linux/mtd/mtd.h>
++#include <linux/nvmem-consumer.h>
++#include <linux/nvmem-provider.h>
++#include <linux/of_device.h>
++#include <linux/platform_device.h>
++#include <linux/slab.h>
++
++enum u_boot_env_format {
++	U_BOOT_FORMAT_SINGLE,
++	U_BOOT_FORMAT_REDUNDANT,
++};
++
++struct u_boot_env {
++	struct device *dev;
++	enum u_boot_env_format format;
++
++	struct mtd_info *mtd;
++
++	/* Cells */
++	struct nvmem_cell_info *cells;
++	int ncells;
++};
++
++struct u_boot_env_image_single {
++	__le32 crc32;
++	uint8_t data[];
++} __packed;
++
++struct u_boot_env_image_redundant {
++	__le32 crc32;
++	u8 mark;
++	uint8_t data[];
++} __packed;
++
++static int u_boot_env_read(void *context, unsigned int offset, void *val,
++			   size_t bytes)
++{
++	struct u_boot_env *priv = context;
++	struct device *dev = priv->dev;
++	size_t bytes_read;
++	int err;
++
++	err = mtd_read(priv->mtd, offset, bytes, &bytes_read, val);
++	if (err && !mtd_is_bitflip(err)) {
++		dev_err(dev, "Failed to read from mtd: %d\n", err);
++		return err;
++	}
++
++	if (bytes_read != bytes) {
++		dev_err(dev, "Failed to read %zu bytes\n", bytes);
++		return -EIO;
++	}
++
++	return 0;
++}
++
++static int u_boot_env_add_cells(struct u_boot_env *priv, uint8_t *buf,
++				size_t data_offset, size_t data_len)
++{
++	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;
++	     var < data + data_len && *var;
++	     var = value + strlen(value) + 1, idx++) {
++		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)
++			return -ENOMEM;
++		priv->cells[idx].offset = data_offset + value - data;
++		priv->cells[idx].bytes = strlen(value);
++	}
++
++	if (WARN_ON(idx != priv->ncells))
++		priv->ncells = idx;
++
++	return 0;
++}
++
++static int u_boot_env_parse(struct u_boot_env *priv)
++{
++	struct device *dev = priv->dev;
++	size_t crc32_data_offset;
++	size_t crc32_data_len;
++	size_t crc32_offset;
++	size_t data_offset;
++	size_t data_len;
++	uint32_t crc32;
++	uint32_t calc;
++	size_t bytes;
++	uint8_t *buf;
++	int err;
++
++	buf = kcalloc(1, priv->mtd->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);
++		goto err_kfree;
++	}
++
++	switch (priv->format) {
++	case U_BOOT_FORMAT_SINGLE:
++		crc32_offset = offsetof(struct u_boot_env_image_single, crc32);
++		crc32_data_offset = offsetof(struct u_boot_env_image_single, data);
++		data_offset = offsetof(struct u_boot_env_image_single, data);
++		break;
++	case U_BOOT_FORMAT_REDUNDANT:
++		crc32_offset = offsetof(struct u_boot_env_image_redundant, crc32);
++		crc32_data_offset = offsetof(struct u_boot_env_image_redundant, mark);
++		data_offset = offsetof(struct u_boot_env_image_redundant, data);
++		break;
++	}
++	crc32 = le32_to_cpu(*(uint32_t *)(buf + crc32_offset));
++	crc32_data_len = priv->mtd->size - crc32_data_offset;
++	data_len = priv->mtd->size - data_offset;
++
++	calc = crc32(~0, buf + crc32_data_offset, crc32_data_len) ^ ~0L;
++	if (calc != crc32) {
++		dev_err(dev, "Invalid calculated CRC32: 0x%08x (expected: 0x%08x)\n", calc, crc32);
++		err = -EINVAL;
++		goto err_kfree;
++	}
++
++	buf[priv->mtd->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);
++err_out:
++	return err;
++}
++
++static int u_boot_env_probe(struct platform_device *pdev)
++{
++	struct nvmem_config config = {
++		.name = "u-boot-env",
++		.reg_read = u_boot_env_read,
++	};
++	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)
++		return -ENOMEM;
++	priv->dev = dev;
++
++	priv->format = (uintptr_t)of_device_get_match_data(dev);
++
++	priv->mtd = of_get_mtd_device_by_node(np);
++	if (IS_ERR(priv->mtd)) {
++		dev_err_probe(dev, PTR_ERR(priv->mtd), "Failed to get %pOF MTD\n", np);
++		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));
++}
++
++static const struct of_device_id u_boot_env_of_match_table[] = {
++	{ .compatible = "u-boot,env", .data = (void *)U_BOOT_FORMAT_SINGLE, },
++	{ .compatible = "u-boot,env-redundant-bool", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
++	{ .compatible = "u-boot,env-redundant-count", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
++	{},
++};
++
++static struct platform_driver u_boot_env_driver = {
++	.probe = u_boot_env_probe,
++	.driver = {
++		.name = "u_boot_env",
++		.of_match_table = u_boot_env_of_match_table,
++	},
++};
++module_platform_driver(u_boot_env_driver);
++
++MODULE_AUTHOR("Rafał Miłecki");
++MODULE_LICENSE("GPL");
++MODULE_DEVICE_TABLE(of, u_boot_env_of_match_table);
diff --git a/target/linux/generic/pending-5.10/400-mtd-mtdsplit-support.patch b/target/linux/generic/pending-5.10/400-mtd-mtdsplit-support.patch
index f37df6d164..ce4743879d 100644
--- a/target/linux/generic/pending-5.10/400-mtd-mtdsplit-support.patch
+++ b/target/linux/generic/pending-5.10/400-mtd-mtdsplit-support.patch
@@ -298,7 +298,7 @@
  static inline uint32_t mtd_div_by_ws(uint64_t sz, struct mtd_info *mtd)
  {
  	if (mtd->writesize_shift)
-@@ -678,6 +696,13 @@ extern void __put_mtd_device(struct mtd_
+@@ -679,6 +697,13 @@ extern struct mtd_info *of_get_mtd_devic
  extern struct mtd_info *get_mtd_device_nm(const char *name);
  extern void put_mtd_device(struct mtd_info *mtd);
  
diff --git a/target/linux/generic/pending-5.10/495-mtd-core-add-get_mtd_device_by_node.patch b/target/linux/generic/pending-5.10/495-mtd-core-add-get_mtd_device_by_node.patch
index cc5946ac05..66017e1648 100644
--- a/target/linux/generic/pending-5.10/495-mtd-core-add-get_mtd_device_by_node.patch
+++ b/target/linux/generic/pending-5.10/495-mtd-core-add-get_mtd_device_by_node.patch
@@ -17,7 +17,7 @@ Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
 
 --- a/drivers/mtd/mtdcore.c
 +++ b/drivers/mtd/mtdcore.c
-@@ -1117,6 +1117,44 @@ out_unlock:
+@@ -1145,6 +1145,44 @@ out_unlock:
  }
  EXPORT_SYMBOL_GPL(get_mtd_device_nm);
  
@@ -64,9 +64,9 @@ Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
  	mutex_lock(&mtd_table_mutex);
 --- a/include/linux/mtd/mtd.h
 +++ b/include/linux/mtd/mtd.h
-@@ -696,6 +696,8 @@ extern struct mtd_info *get_mtd_device(s
- extern int __get_mtd_device(struct mtd_info *mtd);
+@@ -697,6 +697,8 @@ extern int __get_mtd_device(struct mtd_i
  extern void __put_mtd_device(struct mtd_info *mtd);
+ extern struct mtd_info *of_get_mtd_device_by_node(struct device_node *np);
  extern struct mtd_info *get_mtd_device_nm(const char *name);
 +extern struct mtd_info *get_mtd_device_by_node(
 +		const struct device_node *of_node);
diff --git a/target/linux/generic/pending-5.15/400-mtd-mtdsplit-support.patch b/target/linux/generic/pending-5.15/400-mtd-mtdsplit-support.patch
index 8b34f4f467..d07afd70ee 100644
--- a/target/linux/generic/pending-5.15/400-mtd-mtdsplit-support.patch
+++ b/target/linux/generic/pending-5.15/400-mtd-mtdsplit-support.patch
@@ -288,7 +288,7 @@ Subject: [PATCH] mtd: mtdsplit support
  static inline uint32_t mtd_div_by_ws(uint64_t sz, struct mtd_info *mtd)
  {
  	if (mtd->writesize_shift)
-@@ -685,6 +703,13 @@ extern void __put_mtd_device(struct mtd_
+@@ -686,6 +704,13 @@ extern struct mtd_info *of_get_mtd_devic
  extern struct mtd_info *get_mtd_device_nm(const char *name);
  extern void put_mtd_device(struct mtd_info *mtd);
  
diff --git a/target/linux/generic/pending-5.15/495-mtd-core-add-get_mtd_device_by_node.patch b/target/linux/generic/pending-5.15/495-mtd-core-add-get_mtd_device_by_node.patch
index 431c80795e..3e14a1dd31 100644
--- a/target/linux/generic/pending-5.15/495-mtd-core-add-get_mtd_device_by_node.patch
+++ b/target/linux/generic/pending-5.15/495-mtd-core-add-get_mtd_device_by_node.patch
@@ -17,7 +17,7 @@ Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
 
 --- a/drivers/mtd/mtdcore.c
 +++ b/drivers/mtd/mtdcore.c
-@@ -1274,6 +1274,44 @@ out_unlock:
+@@ -1302,6 +1302,44 @@ out_unlock:
  }
  EXPORT_SYMBOL_GPL(get_mtd_device_nm);
  
@@ -64,9 +64,9 @@ Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
  	mutex_lock(&mtd_table_mutex);
 --- a/include/linux/mtd/mtd.h
 +++ b/include/linux/mtd/mtd.h
-@@ -703,6 +703,8 @@ extern struct mtd_info *get_mtd_device(s
- extern int __get_mtd_device(struct mtd_info *mtd);
+@@ -704,6 +704,8 @@ extern int __get_mtd_device(struct mtd_i
  extern void __put_mtd_device(struct mtd_info *mtd);
+ extern struct mtd_info *of_get_mtd_device_by_node(struct device_node *np);
  extern struct mtd_info *get_mtd_device_nm(const char *name);
 +extern struct mtd_info *get_mtd_device_by_node(
 +		const struct device_node *of_node);