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); 101