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 U_BOOT_FORMAT_BROADCOM, 20 }; 21 22 struct u_boot_env { 23 struct device *dev; 24 enum u_boot_env_format format; 25 26 struct mtd_info *mtd; 27 28 /* Cells */ 29 struct nvmem_cell_info *cells; 30 int ncells; 31 }; 32 33 struct u_boot_env_image_single { 34 __le32 crc32; 35 uint8_t data[]; 36 } __packed; 37 38 struct u_boot_env_image_redundant { 39 __le32 crc32; 40 u8 mark; 41 uint8_t data[]; 42 } __packed; 43 44 struct u_boot_env_image_broadcom { 45 __le32 magic; 46 __le32 len; 47 __le32 crc32; 48 uint8_t data[0]; 49 } __packed; 50 51 static int u_boot_env_read(void *context, unsigned int offset, void *val, 52 size_t bytes) 53 { 54 struct u_boot_env *priv = context; 55 struct device *dev = priv->dev; 56 size_t bytes_read; 57 int err; 58 59 err = mtd_read(priv->mtd, offset, bytes, &bytes_read, val); 60 if (err && !mtd_is_bitflip(err)) { 61 dev_err(dev, "Failed to read from mtd: %d\n", err); 62 return err; 63 } 64 65 if (bytes_read != bytes) { 66 dev_err(dev, "Failed to read %zu bytes\n", bytes); 67 return -EIO; 68 } 69 70 return 0; 71 } 72 73 static int u_boot_env_add_cells(struct u_boot_env *priv, uint8_t *buf, 74 size_t data_offset, size_t data_len) 75 { 76 struct device *dev = priv->dev; 77 char *data = buf + data_offset; 78 char *var, *value, *eq; 79 int idx; 80 81 priv->ncells = 0; 82 for (var = data; var < data + data_len && *var; var += strlen(var) + 1) 83 priv->ncells++; 84 85 priv->cells = devm_kcalloc(dev, priv->ncells, sizeof(*priv->cells), GFP_KERNEL); 86 if (!priv->cells) 87 return -ENOMEM; 88 89 for (var = data, idx = 0; 90 var < data + data_len && *var; 91 var = value + strlen(value) + 1, idx++) { 92 eq = strchr(var, '='); 93 if (!eq) 94 break; 95 *eq = '\0'; 96 value = eq + 1; 97 98 priv->cells[idx].name = devm_kstrdup(dev, var, GFP_KERNEL); 99 if (!priv->cells[idx].name) 100 return -ENOMEM; 101 priv->cells[idx].offset = data_offset + value - data; 102 priv->cells[idx].bytes = strlen(value); 103 priv->cells[idx].np = of_get_child_by_name(dev->of_node, priv->cells[idx].name); 104 } 105 106 if (WARN_ON(idx != priv->ncells)) 107 priv->ncells = idx; 108 109 return 0; 110 } 111 112 static int u_boot_env_parse(struct u_boot_env *priv) 113 { 114 struct device *dev = priv->dev; 115 size_t crc32_data_offset; 116 size_t crc32_data_len; 117 size_t crc32_offset; 118 size_t data_offset; 119 size_t data_len; 120 uint32_t crc32; 121 uint32_t calc; 122 size_t bytes; 123 uint8_t *buf; 124 int err; 125 126 buf = kcalloc(1, priv->mtd->size, GFP_KERNEL); 127 if (!buf) { 128 err = -ENOMEM; 129 goto err_out; 130 } 131 132 err = mtd_read(priv->mtd, 0, priv->mtd->size, &bytes, buf); 133 if ((err && !mtd_is_bitflip(err)) || bytes != priv->mtd->size) { 134 dev_err(dev, "Failed to read from mtd: %d\n", err); 135 goto err_kfree; 136 } 137 138 switch (priv->format) { 139 case U_BOOT_FORMAT_SINGLE: 140 crc32_offset = offsetof(struct u_boot_env_image_single, crc32); 141 crc32_data_offset = offsetof(struct u_boot_env_image_single, data); 142 data_offset = offsetof(struct u_boot_env_image_single, data); 143 break; 144 case U_BOOT_FORMAT_REDUNDANT: 145 crc32_offset = offsetof(struct u_boot_env_image_redundant, crc32); 146 crc32_data_offset = offsetof(struct u_boot_env_image_redundant, data); 147 data_offset = offsetof(struct u_boot_env_image_redundant, data); 148 break; 149 case U_BOOT_FORMAT_BROADCOM: 150 crc32_offset = offsetof(struct u_boot_env_image_broadcom, crc32); 151 crc32_data_offset = offsetof(struct u_boot_env_image_broadcom, data); 152 data_offset = offsetof(struct u_boot_env_image_broadcom, data); 153 break; 154 } 155 crc32 = le32_to_cpu(*(__le32 *)(buf + crc32_offset)); 156 crc32_data_len = priv->mtd->size - crc32_data_offset; 157 data_len = priv->mtd->size - data_offset; 158 159 calc = crc32(~0, buf + crc32_data_offset, crc32_data_len) ^ ~0L; 160 if (calc != crc32) { 161 dev_err(dev, "Invalid calculated CRC32: 0x%08x (expected: 0x%08x)\n", calc, crc32); 162 err = -EINVAL; 163 goto err_kfree; 164 } 165 166 buf[priv->mtd->size - 1] = '\0'; 167 err = u_boot_env_add_cells(priv, buf, data_offset, data_len); 168 if (err) 169 dev_err(dev, "Failed to add cells: %d\n", err); 170 171 err_kfree: 172 kfree(buf); 173 err_out: 174 return err; 175 } 176 177 static int u_boot_env_probe(struct platform_device *pdev) 178 { 179 struct nvmem_config config = { 180 .name = "u-boot-env", 181 .reg_read = u_boot_env_read, 182 }; 183 struct device *dev = &pdev->dev; 184 struct device_node *np = dev->of_node; 185 struct u_boot_env *priv; 186 int err; 187 188 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); 189 if (!priv) 190 return -ENOMEM; 191 priv->dev = dev; 192 193 priv->format = (uintptr_t)of_device_get_match_data(dev); 194 195 priv->mtd = of_get_mtd_device_by_node(np); 196 if (IS_ERR(priv->mtd)) { 197 dev_err_probe(dev, PTR_ERR(priv->mtd), "Failed to get %pOF MTD\n", np); 198 return PTR_ERR(priv->mtd); 199 } 200 201 err = u_boot_env_parse(priv); 202 if (err) 203 return err; 204 205 config.dev = dev; 206 config.cells = priv->cells; 207 config.ncells = priv->ncells; 208 config.priv = priv; 209 config.size = priv->mtd->size; 210 211 return PTR_ERR_OR_ZERO(devm_nvmem_register(dev, &config)); 212 } 213 214 static const struct of_device_id u_boot_env_of_match_table[] = { 215 { .compatible = "u-boot,env", .data = (void *)U_BOOT_FORMAT_SINGLE, }, 216 { .compatible = "u-boot,env-redundant-bool", .data = (void *)U_BOOT_FORMAT_REDUNDANT, }, 217 { .compatible = "u-boot,env-redundant-count", .data = (void *)U_BOOT_FORMAT_REDUNDANT, }, 218 { .compatible = "brcm,env", .data = (void *)U_BOOT_FORMAT_BROADCOM, }, 219 {}, 220 }; 221 222 static struct platform_driver u_boot_env_driver = { 223 .probe = u_boot_env_probe, 224 .driver = { 225 .name = "u_boot_env", 226 .of_match_table = u_boot_env_of_match_table, 227 }, 228 }; 229 module_platform_driver(u_boot_env_driver); 230 231 MODULE_AUTHOR("Rafał Miłecki"); 232 MODULE_LICENSE("GPL"); 233 MODULE_DEVICE_TABLE(of, u_boot_env_of_match_table); 234