[RFC PATCH v2 19/20] nvmem: layouts: rewrite the u-boot-env driver as a NVMEM layout

Michael Walle
2022-09-01T22:23:04Z

Instead of hardcoding the underlying access method mtd_read() and
duplicating all the error handling, rewrite the driver as a nvmem
layout which just uses nvmem_device_read() and thus works with any
NVMEM device.

But because this is now not a device anymore, the compatible string
will have to be changed so the device will still be probed:
compatible = "u-boot,env";
to
compatible = "u-boot,env", "nvmem-cells";

"nvmem-cells" will tell the mtd layer to register a nvmem_device().
"u-boot,env" will tell the NVMEM that it should apply the u-boot
environment layout to the NVMEM device.

Signed-off-by: Michael Walle <michael@walle.cc>
---
changes since v1:
- none

drivers/nvmem/layouts/Kconfig | 8 ++
drivers/nvmem/layouts/Makefile | 1 +
drivers/nvmem/layouts/u-boot-env.c | 144 +++++++++++++++++++
drivers/nvmem/u-boot-env.c | 218 -----------------------------
4 files changed, 153 insertions(+), 218 deletions(-)
create mode 100644 drivers/nvmem/layouts/u-boot-env.c
delete mode 100644 drivers/nvmem/u-boot-env.c

diff --git a/drivers/nvmem/layouts/Kconfig b/drivers/nvmem/layouts/Kconfig
index 75082f6b471d..3db0c139a8b7 100644
--- a/drivers/nvmem/layouts/Kconfig
+++ b/drivers/nvmem/layouts/Kconfig
@@ -11,4 +11,12 @@ config NVMEM_LAYOUT_SL28_VPD

If unsure, say N.

+config NVMEM_LAYOUT_U_BOOT_ENV
+ bool "U-Boot environment support"
+ select CRC32
+ help
+ Say Y here if you want to support u-boot's environment.
+
+ If unsure, say N.
+
endmenu
diff --git a/drivers/nvmem/layouts/Makefile b/drivers/nvmem/layouts/Makefile
index fc617b9e87d0..dae93fff2b85 100644
--- a/drivers/nvmem/layouts/Makefile
+++ b/drivers/nvmem/layouts/Makefile
@@ -4,3 +4,4 @@
#

obj-$(CONFIG_NVMEM_LAYOUT_SL28_VPD) += sl28vpd.o
+obj-$(CONFIG_NVMEM_LAYOUT_U_BOOT_ENV) += u-boot-env.o
diff --git a/drivers/nvmem/layouts/u-boot-env.c b/drivers/nvmem/layouts/u-boot-env.c
new file mode 100644
index 000000000000..f184d1424b1e
--- /dev/null
+++ b/drivers/nvmem/layouts/u-boot-env.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2022 Rafał Miłecki <rafal@milecki.pl>
+ */
+
+#include <linux/crc32.h>
+#include <linux/dev_printk.h>
+#include <linux/device.h>
+#include <linux/nvmem-consumer.h>
+#include <linux/nvmem-provider.h>
+#include <linux/slab.h>
+
+enum u_boot_env_format {
+ U_BOOT_FORMAT_SINGLE,
+ U_BOOT_FORMAT_REDUNDANT,
+};
+
+struct u_boot_env_image_single {
+ __le32 crc32;
+ u8 data[];
+} __packed;
+
+struct u_boot_env_image_redundant {
+ __le32 crc32;
+ u8 mark;
+ u8 data[];
+} __packed;
+
+static int u_boot_env_add_cells(struct device *dev,
+ struct nvmem_device *nvmem, uint8_t *buf,
+ size_t data_offset, size_t data_len)
+{
+ struct nvmem_cell_info info = {0};
+ char *data = buf + data_offset;
+ char *var, *value, *eq;
+ int err;
+
+ for (var = data;
+ var < data + data_len && *var;
+ var = value + strlen(value) + 1) {
+ eq = strchr(var, '=');
+ if (!eq)
+ break;
+ *eq = '\0';
+ value = eq + 1;
+
+ info.name = var;
+ info.offset = data_offset + value - data;
+ info.bytes = strlen(value);
+
+ err = nvmem_add_one_cell(nvmem, &info);
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
+static int u_boot_add_cells(struct device *dev, struct nvmem_device *nvmem,
+ struct nvmem_layout *layout)
+{
+ size_t size = nvmem_device_size(nvmem);
+ enum u_boot_env_format format;
+ size_t crc32_data_offset;
+ size_t crc32_data_len;
+ size_t crc32_offset;
+ size_t data_offset;
+ size_t data_len;
+ u32 crc32;
+ u32 calc;
+ u8 *buf;
+ int err;
+
+ format = (uintptr_t)nvmem_layout_get_match_data(nvmem, layout);
+
+ buf = kzalloc(size, GFP_KERNEL);
+ if (!buf) {
+ err = -ENOMEM;
+ goto err_out;
+ }
+
+ err = nvmem_device_read(nvmem, 0, size, buf);
+ if (err < 0) {
+ dev_err(dev, "Failed to read from nvmem device (%pe)\n",
+ ERR_PTR(err));
+ goto err_kfree;
+ } else if (err != size) {
+ dev_err(dev, "Short read from nvmem device.\n");
+ 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, mark);
+ data_offset = offsetof(struct u_boot_env_image_redundant, data);
+ break;
+ }
+ crc32 = le32_to_cpu(*(u32 *)(buf + crc32_offset));
+ crc32_data_len = size - crc32_data_offset;
+ data_len = 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[size - 1] = '\0';
+ err = u_boot_env_add_cells(dev, nvmem, 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 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 nvmem_layout u_boot_env_layout = {
+ .name = "u_boot_env",
+ .of_match_table = u_boot_env_of_match_table,
+ .add_cells = u_boot_add_cells,
+};
+
+static int __init u_boot_env_init(void)
+{
+ return nvmem_layout_register(&u_boot_env_layout);
+}
+subsys_initcall(u_boot_env_init);
diff --git a/drivers/nvmem/u-boot-env.c b/drivers/nvmem/u-boot-env.c
deleted file mode 100644
index 9b9abfb8f187..000000000000
--- a/drivers/nvmem/u-boot-env.c
+++ /dev/null
@@ -1,218 +0,0 @@
-// 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);
--
2.30.2