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// 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);
priv->cells[idx].np = of_get_child_by_name(dev->of_node, priv->cells[idx].name);
}
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, data);
data_offset = offsetof(struct u_boot_env_image_redundant, 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;
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);
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