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