nvmem: layouts: add U-Boot env layout

U-Boot environment variables are stored in a specific format. Actual
data can be placed in various storage sources (MTD, UBI volume, EEPROM,
NVRAM, etc.).

Move all generic (NVMEM device independent) code from NVMEM device
driver to an NVMEM layout driver. Then add a simple NVMEM layout code on
top of it.

This allows using NVMEM layout for parsing U-Boot env data stored in any
kind of NVMEM device.

The old NVMEM glue driver stays in place for handling bindings in the
MTD context. To avoid code duplication it uses exported layout parsing
function. Please note that handling MTD & NVMEM layout bindings may be
refactored in the future.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20240902142952.71639-5-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

MAINTAINERS

@@ -23458,6 +23458,7 @@ U-BOOT ENVIRONMENT VARIABLES
 M:	Rafał Miłecki <rafal@milecki.pl>
 S:	Maintained
 F:	Documentation/devicetree/bindings/nvmem/u-boot,env.yaml
+F:	drivers/nvmem/layouts/u-boot-env.c
 F:	drivers/nvmem/u-boot-env.c
 
 UACCE ACCELERATOR FRAMEWORK

drivers/nvmem/Kconfig

@@ -363,8 +363,7 @@ config NVMEM_SUNXI_SID
 config NVMEM_U_BOOT_ENV
 	tristate "U-Boot environment variables support"
 	depends on OF && MTD
-	select CRC32
-	select GENERIC_NET_UTILS
+	select NVMEM_LAYOUT_U_BOOT_ENV
 	help
 	  U-Boot stores its setup as environment variables. This driver adds
 	  support for verifying & exporting such data. It also exposes variables

drivers/nvmem/layouts/Kconfig

@@ -26,6 +26,17 @@ config NVMEM_LAYOUT_ONIE_TLV
 
 	  If unsure, say N.
 
+config NVMEM_LAYOUT_U_BOOT_ENV
+	tristate "U-Boot environment variables layout"
+	select CRC32
+	select GENERIC_NET_UTILS
+	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.
+
+	  If unsure, say N.
+
 endmenu
 
 endif

drivers/nvmem/layouts/Makefile

@@ -5,3 +5,4 @@
 
 obj-$(CONFIG_NVMEM_LAYOUT_SL28_VPD) += sl28vpd.o
 obj-$(CONFIG_NVMEM_LAYOUT_ONIE_TLV) += onie-tlv.o
+obj-$(CONFIG_NVMEM_LAYOUT_U_BOOT_ENV) += u-boot-env.o

drivers/nvmem/layouts/u-boot-env.c

@@ -0,0 +1,211 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2022 - 2023 Rafał Miłecki <rafal@milecki.pl>
+ */
+
+#include <linux/crc32.h>
+#include <linux/etherdevice.h>
+#include <linux/export.h>
+#include <linux/if_ether.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/nvmem-provider.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+#include "u-boot-env.h"
+
+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;
+
+struct u_boot_env_image_broadcom {
+	__le32 magic;
+	__le32 len;
+	__le32 crc32;
+	DECLARE_FLEX_ARRAY(uint8_t, data);
+} __packed;
+
+static int u_boot_env_read_post_process_ethaddr(void *context, const char *id, int index,
+						unsigned int offset, void *buf, size_t bytes)
+{
+	u8 mac[ETH_ALEN];
+
+	if (bytes != 3 * ETH_ALEN - 1)
+		return -EINVAL;
+
+	if (!mac_pton(buf, mac))
+		return -EINVAL;
+
+	if (index)
+		eth_addr_add(mac, index);
+
+	ether_addr_copy(buf, mac);
+
+	return 0;
+}
+
+static int u_boot_env_parse_cells(struct device *dev, struct nvmem_device *nvmem, uint8_t *buf,
+				  size_t data_offset, size_t data_len)
+{
+	char *data = buf + data_offset;
+	char *var, *value, *eq;
+
+	for (var = data;
+	     var < data + data_len && *var;
+	     var = value + strlen(value) + 1) {
+		struct nvmem_cell_info info = {};
+
+		eq = strchr(var, '=');
+		if (!eq)
+			break;
+		*eq = '\0';
+		value = eq + 1;
+
+		info.name = devm_kstrdup(dev, var, GFP_KERNEL);
+		if (!info.name)
+			return -ENOMEM;
+		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")) {
+			info.raw_len = strlen(value);
+			info.bytes = ETH_ALEN;
+			info.read_post_process = u_boot_env_read_post_process_ethaddr;
+		}
+
+		nvmem_add_one_cell(nvmem, &info);
+	}
+
+	return 0;
+}
+
+int u_boot_env_parse(struct device *dev, struct nvmem_device *nvmem,
+		     enum u_boot_env_format format)
+{
+	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;
+	uint8_t *buf;
+	int bytes;
+	int err;
+
+	dev_size = nvmem_dev_size(nvmem);
+
+	buf = kzalloc(dev_size, GFP_KERNEL);
+	if (!buf) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+
+	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;
+	}
+
+	switch (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, data);
+		data_offset = offsetof(struct u_boot_env_image_redundant, data);
+		break;
+	case U_BOOT_FORMAT_BROADCOM:
+		crc32_offset = offsetof(struct u_boot_env_image_broadcom, crc32);
+		crc32_data_offset = offsetof(struct u_boot_env_image_broadcom, data);
+		data_offset = offsetof(struct u_boot_env_image_broadcom, data);
+		break;
+	}
+
+	if (dev_size < data_offset) {
+		dev_err(dev, "Device too small for u-boot-env\n");
+		err = -EIO;
+		goto err_kfree;
+	}
+
+	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) {
+		dev_err(dev, "Invalid calculated CRC32: 0x%08x (expected: 0x%08x)\n", calc, crc32);
+		err = -EINVAL;
+		goto err_kfree;
+	}
+
+	buf[dev_size - 1] = '\0';
+	err = u_boot_env_parse_cells(dev, nvmem, buf, data_offset, data_len);
+
+err_kfree:
+	kfree(buf);
+err_out:
+	return err;
+}
+EXPORT_SYMBOL_GPL(u_boot_env_parse);
+
+static int u_boot_env_add_cells(struct nvmem_layout *layout)
+{
+	struct device *dev = &layout->dev;
+	enum u_boot_env_format format;
+
+	format = (uintptr_t)device_get_match_data(dev);
+
+	return u_boot_env_parse(dev, layout->nvmem, format);
+}
+
+static int u_boot_env_probe(struct nvmem_layout *layout)
+{
+	layout->add_cells = u_boot_env_add_cells;
+
+	return nvmem_layout_register(layout);
+}
+
+static void u_boot_env_remove(struct nvmem_layout *layout)
+{
+	nvmem_layout_unregister(layout);
+}
+
+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, },
+	{ .compatible = "brcm,env", .data = (void *)U_BOOT_FORMAT_BROADCOM, },
+	{},
+};
+
+static struct nvmem_layout_driver u_boot_env_layout = {
+	.driver = {
+		.name = "u-boot-env-layout",
+		.of_match_table = u_boot_env_of_match_table,
+	},
+	.probe = u_boot_env_probe,
+	.remove = u_boot_env_remove,
+};
+module_nvmem_layout_driver(u_boot_env_layout);
+
+MODULE_AUTHOR("Rafał Miłecki");
+MODULE_LICENSE("GPL");
+MODULE_DEVICE_TABLE(of, u_boot_env_of_match_table);
+MODULE_DESCRIPTION("NVMEM layout driver for U-Boot environment variables");

drivers/nvmem/layouts/u-boot-env.h

@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef _LINUX_NVMEM_LAYOUTS_U_BOOT_ENV_H
+#define _LINUX_NVMEM_LAYOUTS_U_BOOT_ENV_H
+
+enum u_boot_env_format {
+	U_BOOT_FORMAT_SINGLE,
+	U_BOOT_FORMAT_REDUNDANT,
+	U_BOOT_FORMAT_BROADCOM,
+};
+
+int u_boot_env_parse(struct device *dev, struct nvmem_device *nvmem,
+		     enum u_boot_env_format format);
+
+#endif  /* ifndef _LINUX_NVMEM_LAYOUTS_U_BOOT_ENV_H */

drivers/nvmem/u-boot-env.c

@@ -3,23 +3,15 @@
  * Copyright (C) 2022 Rafał Miłecki <rafal@milecki.pl>
  */
 
-#include <linux/crc32.h>
-#include <linux/etherdevice.h>
-#include <linux/if_ether.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.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 
-enum u_boot_env_format {
-	U_BOOT_FORMAT_SINGLE,
-	U_BOOT_FORMAT_REDUNDANT,
-	U_BOOT_FORMAT_BROADCOM,
-};
+#include "layouts/u-boot-env.h"
 
 struct u_boot_env {
 	struct device *dev;
@@ -29,24 +21,6 @@ struct u_boot_env {
 	struct mtd_info *mtd;
 };
 
-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;
-
-struct u_boot_env_image_broadcom {
-	__le32 magic;
-	__le32 len;
-	__le32 crc32;
-	DECLARE_FLEX_ARRAY(uint8_t, data);
-} __packed;
-
 static int u_boot_env_read(void *context, unsigned int offset, void *val,
 			   size_t bytes)
 {
@@ -69,141 +43,6 @@ static int u_boot_env_read(void *context, unsigned int offset, void *val,
 	return 0;
 }
 
-static int u_boot_env_read_post_process_ethaddr(void *context, const char *id, int index,
-						unsigned int offset, void *buf, size_t bytes)
-{
-	u8 mac[ETH_ALEN];
-
-	if (bytes != 3 * ETH_ALEN - 1)
-		return -EINVAL;
-
-	if (!mac_pton(buf, mac))
-		return -EINVAL;
-
-	if (index)
-		eth_addr_add(mac, index);
-
-	ether_addr_copy(buf, mac);
-
-	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 nvmem_device *nvmem = priv->nvmem;
-	struct device *dev = priv->dev;
-	char *data = buf + data_offset;
-	char *var, *value, *eq;
-
-	for (var = data;
-	     var < data + data_len && *var;
-	     var = value + strlen(value) + 1) {
-		struct nvmem_cell_info info = {};
-
-		eq = strchr(var, '=');
-		if (!eq)
-			break;
-		*eq = '\0';
-		value = eq + 1;
-
-		info.name = devm_kstrdup(dev, var, GFP_KERNEL);
-		if (!info.name)
-			return -ENOMEM;
-		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")) {
-			info.raw_len = strlen(value);
-			info.bytes = ETH_ALEN;
-			info.read_post_process = u_boot_env_read_post_process_ethaddr;
-		}
-
-		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;
-	uint8_t *buf;
-	int bytes;
-	int err;
-
-	dev_size = nvmem_dev_size(nvmem);
-
-	buf = kzalloc(dev_size, GFP_KERNEL);
-	if (!buf) {
-		err = -ENOMEM;
-		goto err_out;
-	}
-
-	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;
-	}
-
-	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, data);
-		data_offset = offsetof(struct u_boot_env_image_redundant, data);
-		break;
-	case U_BOOT_FORMAT_BROADCOM:
-		crc32_offset = offsetof(struct u_boot_env_image_broadcom, crc32);
-		crc32_data_offset = offsetof(struct u_boot_env_image_broadcom, data);
-		data_offset = offsetof(struct u_boot_env_image_broadcom, data);
-		break;
-	}
-
-	if (dev_size < data_offset) {
-		dev_err(dev, "Device too small for u-boot-env\n");
-		err = -EIO;
-		goto err_kfree;
-	}
-
-	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) {
-		dev_err(dev, "Invalid calculated CRC32: 0x%08x (expected: 0x%08x)\n", calc, crc32);
-		err = -EINVAL;
-		goto err_kfree;
-	}
-
-	buf[dev_size - 1] = '\0';
-	err = u_boot_env_add_cells(priv, buf, data_offset, data_len);
-
-err_kfree:
-	kfree(buf);
-err_out:
-	return err;
-}
-
 static int u_boot_env_probe(struct platform_device *pdev)
 {
 	struct nvmem_config config = {
@@ -235,7 +74,7 @@ static int u_boot_env_probe(struct platform_device *pdev)
 	if (IS_ERR(priv->nvmem))
 		return PTR_ERR(priv->nvmem);
 
-	return u_boot_env_parse(priv);
+	return u_boot_env_parse(dev, priv->nvmem, priv->format);
 }
 
 static const struct of_device_id u_boot_env_of_match_table[] = {