drivers/nvmem/u-boot-env.c

   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
  16 struct 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
  24 static 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
  46 static 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
  80 static 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
  88 static 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 };
  95 module_platform_driver(u_boot_env_driver);
  96
  97 MODULE_AUTHOR("Rafał Miłecki");
  98 MODULE_DESCRIPTION("U-Boot environment variables support module");
  99 MODULE_LICENSE("GPL");
 100 MODULE_DEVICE_TABLE(of, u_boot_env_of_match_table);