[PATCH V2 3/3] nvmem: add driver handling U-Boot environment variables
Rafał Miłecki
zajec5 at gmail.com
Thu Dec 30 01:04:49 PST 2021
From: Rafał Miłecki <rafal at milecki.pl>
U-Boot binary contains a block of environment variables (NVMEM) that
should be parsed and exposed as NVMEM cells.
Signed-off-by: Rafał Miłecki <rafal at milecki.pl>
---
V2: Drop debugging dev_info() call
Fix variable type mismatch
---
MAINTAINERS | 1 +
drivers/nvmem/Kconfig | 10 ++
drivers/nvmem/Makefile | 2 +
drivers/nvmem/u-boot-env.c | 235 +++++++++++++++++++++++++++++++++++++
4 files changed, 248 insertions(+)
create mode 100644 drivers/nvmem/u-boot-env.c
diff --git a/MAINTAINERS b/MAINTAINERS
index 271c29c84c7d..cc9bdeb33b64 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19628,6 +19628,7 @@ U-BOOT ENVIRONMENT VARIABLES
M: Rafał Miłecki <rafal at milecki.pl>
S: Maintained
F: Documentation/devicetree/bindings/nvmem/u-boot,env.yaml
+F: drivers/nvmem/u-boot-env.c
UACCE ACCELERATOR FRAMEWORK
M: Zhangfei Gao <zhangfei.gao at linaro.org>
diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
index da414617a54d..af9115852412 100644
--- a/drivers/nvmem/Kconfig
+++ b/drivers/nvmem/Kconfig
@@ -300,4 +300,14 @@ 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 ARCH_BCM4908 || COMPILE_TEST
+ depends on OF
+ help
+ This driver adds support for parsing U-Boot environment variables
+ stored on flash partition.
+
+ If compiled as module it will be called nvmem_u-boot-env.
+
endif
diff --git a/drivers/nvmem/Makefile b/drivers/nvmem/Makefile
index dcbbde35b6a8..772904cdebdb 100644
--- a/drivers/nvmem/Makefile
+++ b/drivers/nvmem/Makefile
@@ -61,3 +61,5 @@ obj-$(CONFIG_NVMEM_RMEM) += nvmem-rmem.o
nvmem-rmem-y := rmem.o
obj-$(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
diff --git a/drivers/nvmem/u-boot-env.c b/drivers/nvmem/u-boot-env.c
new file mode 100644
index 000000000000..42626c552d37
--- /dev/null
+++ b/drivers/nvmem/u-boot-env.c
@@ -0,0 +1,235 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2021 Rafał Miłecki <rafal at 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_DEFAULT,
+ U_BOOT_FORMAT_BRCM,
+};
+
+struct u_boot_env {
+ struct device *dev;
+ enum u_boot_env_format format;
+ struct mtd_info *mtd;
+ size_t offset;
+ size_t size;
+ struct nvmem_cell_info *cells;
+ int ncells;
+};
+
+struct u_boot_env_image {
+ __le32 crc32;
+ uint8_t data[0];
+} __packed;
+
+struct u_boot_brcm_header {
+ __le32 unk;
+ __le32 len;
+} __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, priv->offset + 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 %zd bytes\n", bytes);
+ return err;
+ }
+
+ return 0;
+}
+
+static int u_boot_env_add_cells(struct u_boot_env *priv, size_t data_offset,
+ uint8_t *data, size_t len)
+{
+ struct device *dev = priv->dev;
+ char *var, *value, *eq;
+ int idx;
+
+ priv->ncells = 0;
+ for (var = data; var < (char *)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 < (char *)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 - (char *)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;
+ struct u_boot_env_image *image;
+ size_t image_offset;
+ size_t image_len;
+ uint32_t crc32;
+ size_t bytes;
+ uint8_t *buf;
+ int err;
+
+ image_offset = 0;
+ image_len = priv->size;
+ if (priv->format == U_BOOT_FORMAT_BRCM) {
+ struct u_boot_brcm_header header;
+
+ err = mtd_read(priv->mtd, priv->offset, sizeof(header), &bytes,
+ (uint8_t *)&header);
+ if (err && !mtd_is_bitflip(err)) {
+ dev_err(dev, "Failed to read from mtd: %d\n", err);
+ return err;
+ }
+
+ image_offset = sizeof(header);
+ image_len = le32_to_cpu(header.len);
+ }
+
+ buf = kcalloc(1, image_len, GFP_KERNEL);
+ if (!buf) {
+ err = -ENOMEM;
+ goto err_out;
+ }
+ image = (struct u_boot_env_image *)buf;
+
+ err = mtd_read(priv->mtd, priv->offset + image_offset, image_len, &bytes, buf);
+ if (err && !mtd_is_bitflip(err)) {
+ dev_err(dev, "Failed to read from mtd: %d\n", err);
+ goto err_kfree;
+ }
+
+ crc32 = crc32(~0, buf + 4, image_len - 4) ^ ~0L;
+ if (crc32 != le32_to_cpu(image->crc32)) {
+ dev_err(dev, "Invalid calculated CRC32: 0x%08x\n", crc32);
+ err = -EINVAL;
+ goto err_kfree;
+ }
+
+ buf[image_len - 1] = '\0';
+ err = u_boot_env_add_cells(priv, image_offset + sizeof(*image),
+ buf + sizeof(*image),
+ image_len - sizeof(*image));
+ if (err)
+ dev_err(dev, "Failed to add cells: %d\n", err);
+
+err_kfree:
+ kfree(buf);
+err_out:
+ return err;
+}
+
+static const struct of_device_id u_boot_env_of_match_table[] = {
+ { .compatible = "u-boot,env", .data = (void *)U_BOOT_FORMAT_DEFAULT, },
+ { .compatible = "brcm,env", .data = (void *)U_BOOT_FORMAT_BRCM, },
+ {},
+};
+
+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;
+ const struct of_device_id *of_id;
+ struct u_boot_env *priv;
+ const char *label;
+ int err;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+ priv->dev = dev;
+
+ of_id = of_match_device(u_boot_env_of_match_table, dev);
+ if (!of_id)
+ return -EINVAL;
+ priv->format = (uintptr_t)of_id->data;
+
+ if (of_property_read_u32(np, "reg", (u32 *)&priv->offset) ||
+ of_property_read_u32_index(np, "reg", 1, (u32 *)&priv->size)) {
+ dev_err(dev, "Failed to read \"reg\" property\n");
+ return -EINVAL;
+ }
+
+ label = of_get_property(np->parent, "label", NULL);
+ if (!label)
+ label = np->parent->name;
+
+ priv->mtd = get_mtd_device_nm(label);
+ if (IS_ERR(priv->mtd)) {
+ dev_err(dev, "Failed to find \"%s\" MTD device: %ld\n", label, PTR_ERR(priv->mtd));
+ 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->size;
+
+ return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config));
+}
+
+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,
+ },
+};
+
+static int __init u_boot_env_init(void)
+{
+ return platform_driver_register(&u_boot_env_driver);
+}
+
+subsys_initcall_sync(u_boot_env_init);
+
+MODULE_AUTHOR("Rafał Miłecki");
+MODULE_LICENSE("GPL");
+MODULE_DEVICE_TABLE(of, u_boot_env_of_match_table);
--
2.31.1
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