1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (C) 2022 Rafał Miłecki <rafal@milecki.pl>
  4 */
  5
  6#include <linux/mod_devicetable.h>
  7#include <linux/module.h>
  8#include <linux/mtd/mtd.h>
  9#include <linux/nvmem-provider.h>
 10#include <linux/of.h>
 11#include <linux/platform_device.h>
 12#include <linux/slab.h>
 13
 14#include "layouts/u-boot-env.h"
 15
 16struct u_boot_env {
 17	struct device *dev;
 18	struct nvmem_device *nvmem;
 19	enum u_boot_env_format format;
 20
 21	struct mtd_info *mtd;
 22};
 23
 24static int u_boot_env_read(void *context, unsigned int offset, void *val,
 25			   size_t bytes)
 26{
 27	struct u_boot_env *priv = context;
 28	struct device *dev = priv->dev;
 29	size_t bytes_read;
 30	int err;
 31
 32	err = mtd_read(priv->mtd, offset, bytes, &bytes_read, val);
 33	if (err && !mtd_is_bitflip(err)) {
 34		dev_err(dev, "Failed to read from mtd: %d\n", err);
 35		return err;
 36	}
 37
 38	if (bytes_read != bytes) {
 39		dev_err(dev, "Failed to read %zu bytes\n", bytes);
 40		return -EIO;
 41	}
 42
 43	return 0;
 44}
 45
 46static int u_boot_env_probe(struct platform_device *pdev)
 47{
 48	struct nvmem_config config = {
 49		.name = "u-boot-env",
 50		.reg_read = u_boot_env_read,
 51	};
 52	struct device *dev = &pdev->dev;
 53	struct device_node *np = dev->of_node;
 54	struct u_boot_env *priv;
 55
 56	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 57	if (!priv)
 58		return -ENOMEM;
 59	priv->dev = dev;
 60
 61	priv->format = (uintptr_t)of_device_get_match_data(dev);
 62
 63	priv->mtd = of_get_mtd_device_by_node(np);
 64	if (IS_ERR(priv->mtd)) {
 65		dev_err_probe(dev, PTR_ERR(priv->mtd), "Failed to get %pOF MTD\n", np);
 66		return PTR_ERR(priv->mtd);
 67	}
 68
 69	config.dev = dev;
 70	config.priv = priv;
 71	config.size = priv->mtd->size;
 72
 73	priv->nvmem = devm_nvmem_register(dev, &config);
 74	if (IS_ERR(priv->nvmem))
 75		return PTR_ERR(priv->nvmem);
 76
 77	return u_boot_env_parse(dev, priv->nvmem, priv->format);
 78}
 79
 80static const struct of_device_id u_boot_env_of_match_table[] = {
 81	{ .compatible = "u-boot,env", .data = (void *)U_BOOT_FORMAT_SINGLE, },
 82	{ .compatible = "u-boot,env-redundant-bool", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
 83	{ .compatible = "u-boot,env-redundant-count", .data = (void *)U_BOOT_FORMAT_REDUNDANT, },
 84	{ .compatible = "brcm,env", .data = (void *)U_BOOT_FORMAT_BROADCOM, },
 85	{},
 86};
 87
 88static struct platform_driver u_boot_env_driver = {
 89	.probe = u_boot_env_probe,
 90	.driver = {
 91		.name = "u_boot_env",
 92		.of_match_table = u_boot_env_of_match_table,
 93	},
 94};
 95module_platform_driver(u_boot_env_driver);
 96
 97MODULE_AUTHOR("Rafał Miłecki");
 98MODULE_DESCRIPTION("U-Boot environment variables support module");
 99MODULE_LICENSE("GPL");
100MODULE_DEVICE_TABLE(of, u_boot_env_of_match_table);