1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2022 Rafał Miłecki <rafal@milecki.pl> 4 */ 5 6 #include <linux/crc32.h> 7 #include <linux/mod_devicetable.h> 8 #include <linux/module.h> 9 #include <linux/mtd/mtd.h> 10 #include <linux/nvmem-consumer.h> 11 #include <linux/nvmem-provider.h> 12 #include <linux/of_device.h> 13 #include <linux/platform_device.h> 14 #include <linux/slab.h> 15 16 enum u_boot_env_format { 17 U_BOOT_FORMAT_SINGLE, 18 U_BOOT_FORMAT_REDUNDANT, 19 }; 20 21 struct u_boot_env { 22 struct device *dev; 23 enum u_boot_env_format format; 24 25 struct mtd_info *mtd; 26 27 /* Cells */ 28 struct nvmem_cell_info *cells; 29 int ncells; 30 }; 31 32 struct u_boot_env_image_single { 33 __le32 crc32; 34 uint8_t data[]; 35 } __packed; 36 37 struct u_boot_env_image_redundant { 38 __le32 crc32; 39 u8 mark; 40 uint8_t data[]; 41 } __packed; 42 43 static int u_boot_env_read(void *context, unsigned int offset, void *val, 44 size_t bytes) 45 { 46 struct u_boot_env *priv = context; 47 struct device *dev = priv->dev; 48 size_t bytes_read; 49 int err; 50 51 err = mtd_read(priv->mtd, offset, bytes, &bytes_read, val); 52 if (err && !mtd_is_bitflip(err)) { 53 dev_err(dev, "Failed to read from mtd: %d\n", err); 54 return err; 55 } 56 57 if (bytes_read != bytes) { 58 dev_err(dev, "Failed to read %zu bytes\n", bytes); 59 return -EIO; 60 } 61 62 return 0; 63 } 64 65 static int u_boot_env_add_cells(struct u_boot_env *priv, uint8_t *buf, 66 size_t data_offset, size_t data_len) 67 { 68 struct device *dev = priv->dev; 69 char *data = buf + data_offset; 70 char *var, *value, *eq; 71 int idx; 72 73 priv->ncells = 0; 74 for (var = data; var < data + data_len && *var; var += strlen(var) + 1) 75 priv->ncells++; 76 77 priv->cells = devm_kcalloc(dev, priv->ncells, sizeof(*priv->cells), GFP_KERNEL); 78 if (!priv->cells) 79 return -ENOMEM; 80 81 for (var = data, idx = 0; 82 var < data + data_len && *var; 83 var = value + strlen(value) + 1, idx++) { 84 eq = strchr(var, '='); 85 if (!eq) 86 break; 87 *eq = '\0'; 88 value = eq + 1; 89 90 priv->cells[idx].name = devm_kstrdup(dev, var, GFP_KERNEL); 91 if (!priv->cells[idx].name) 92 return -ENOMEM; 93 priv->cells[idx].offset = data_offset + value - data; 94 priv->cells[idx].bytes = strlen(value); 95 priv->cells[idx].np = of_get_child_by_name(dev->of_node, priv->cells[idx].name); 96 } 97 98 if (WARN_ON(idx != priv->ncells)) 99 priv->ncells = idx; 100 101 return 0; 102 } 103 104 static int u_boot_env_parse(struct u_boot_env *priv) 105 { 106 struct device *dev = priv->dev; 107 size_t crc32_data_offset; 108 size_t crc32_data_len; 109 size_t crc32_offset; 110 size_t data_offset; 111 size_t data_len; 112 uint32_t crc32; 113 uint32_t calc; 114 size_t bytes; 115 uint8_t *buf; 116 int err; 117 118 buf = kcalloc(1, priv->mtd->size, GFP_KERNEL); 119 if (!buf) { 120 err = -ENOMEM; 121 goto err_out; 122 } 123 124 err = mtd_read(priv->mtd, 0, priv->mtd->size, &bytes, buf); 125 if ((err && !mtd_is_bitflip(err)) || bytes != priv->mtd->size) { 126 dev_err(dev, "Failed to read from mtd: %d\n", err); 127 goto err_kfree; 128 } 129 130 switch (priv->format) { 131 case U_BOOT_FORMAT_SINGLE: 132 crc32_offset = offsetof(struct u_boot_env_image_single, crc32); 133 crc32_data_offset = offsetof(struct u_boot_env_image_single, data); 134 data_offset = offsetof(struct u_boot_env_image_single, data); 135 break; 136 case U_BOOT_FORMAT_REDUNDANT: 137 crc32_offset = offsetof(struct u_boot_env_image_redundant, crc32); 138 crc32_data_offset = offsetof(struct u_boot_env_image_redundant, mark); 139 data_offset = offsetof(struct u_boot_env_image_redundant, data); 140 break; 141 } 142 crc32 = le32_to_cpu(*(__le32 *)(buf + crc32_offset)); 143 crc32_data_len = priv->mtd->size - crc32_data_offset; 144 data_len = priv->mtd->size - data_offset; 145 146 calc = crc32(~0, buf + crc32_data_offset, crc32_data_len) ^ ~0L; 147 if (calc != crc32) { 148 dev_err(dev, "Invalid calculated CRC32: 0x%08x (expected: 0x%08x)\n", calc, crc32); 149 err = -EINVAL; 150 goto err_kfree; 151 } 152 153 buf[priv->mtd->size - 1] = '\0'; 154 err = u_boot_env_add_cells(priv, buf, data_offset, data_len); 155 if (err) 156 dev_err(dev, "Failed to add cells: %d\n", err); 157 158 err_kfree: 159 kfree(buf); 160 err_out: 161 return err; 162 } 163 164 static int u_boot_env_probe(struct platform_device *pdev) 165 { 166 struct nvmem_config config = { 167 .name = "u-boot-env", 168 .reg_read = u_boot_env_read, 169 }; 170 struct device *dev = &pdev->dev; 171 struct device_node *np = dev->of_node; 172 struct u_boot_env *priv; 173 int err; 174 175 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); 176 if (!priv) 177 return -ENOMEM; 178 priv->dev = dev; 179 180 priv->format = (uintptr_t)of_device_get_match_data(dev); 181 182 priv->mtd = of_get_mtd_device_by_node(np); 183 if (IS_ERR(priv->mtd)) { 184 dev_err_probe(dev, PTR_ERR(priv->mtd), "Failed to get %pOF MTD\n", np); 185 return PTR_ERR(priv->mtd); 186 } 187 188 err = u_boot_env_parse(priv); 189 if (err) 190 return err; 191 192 config.dev = dev; 193 config.cells = priv->cells; 194 config.ncells = priv->ncells; 195 config.priv = priv; 196 config.size = priv->mtd->size; 197 198 return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config)); 199 } 200 201 static const struct of_device_id u_boot_env_of_match_table[] = { 202 { .compatible = "u-boot,env", .data = (void *)U_BOOT_FORMAT_SINGLE, }, 203 { .compatible = "u-boot,env-redundant-bool", .data = (void *)U_BOOT_FORMAT_REDUNDANT, }, 204 { .compatible = "u-boot,env-redundant-count", .data = (void *)U_BOOT_FORMAT_REDUNDANT, }, 205 {}, 206 }; 207 208 static struct platform_driver u_boot_env_driver = { 209 .probe = u_boot_env_probe, 210 .driver = { 211 .name = "u_boot_env", 212 .of_match_table = u_boot_env_of_match_table, 213 }, 214 }; 215 module_platform_driver(u_boot_env_driver); 216 217 MODULE_AUTHOR("Rafał Miłecki"); 218 MODULE_LICENSE("GPL"); 219 MODULE_DEVICE_TABLE(of, u_boot_env_of_match_table); 220