1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * BCM947xx nvram variable access 4 * 5 * Copyright (C) 2005 Broadcom Corporation 6 * Copyright (C) 2006 Felix Fietkau <nbd@openwrt.org> 7 * Copyright (C) 2010-2012 Hauke Mehrtens <hauke@hauke-m.de> 8 */ 9 10 #include <linux/io.h> 11 #include <linux/types.h> 12 #include <linux/module.h> 13 #include <linux/kernel.h> 14 #include <linux/string.h> 15 #include <linux/mtd/mtd.h> 16 #include <linux/bcm47xx_nvram.h> 17 18 #define NVRAM_MAGIC 0x48534C46 /* 'FLSH' */ 19 #define NVRAM_SPACE 0x10000 20 #define NVRAM_MAX_GPIO_ENTRIES 32 21 #define NVRAM_MAX_GPIO_VALUE_LEN 30 22 23 #define FLASH_MIN 0x00020000 /* Minimum flash size */ 24 25 struct nvram_header { 26 u32 magic; 27 u32 len; 28 u32 crc_ver_init; /* 0:7 crc, 8:15 ver, 16:31 sdram_init */ 29 u32 config_refresh; /* 0:15 sdram_config, 16:31 sdram_refresh */ 30 u32 config_ncdl; /* ncdl values for memc */ 31 }; 32 33 static char nvram_buf[NVRAM_SPACE]; 34 static size_t nvram_len; 35 static const u32 nvram_sizes[] = {0x6000, 0x8000, 0xF000, 0x10000}; 36 37 /** 38 * bcm47xx_nvram_is_valid - check for a valid NVRAM at specified memory 39 */ 40 static bool bcm47xx_nvram_is_valid(void __iomem *nvram) 41 { 42 return ((struct nvram_header *)nvram)->magic == NVRAM_MAGIC; 43 } 44 45 /** 46 * bcm47xx_nvram_copy - copy NVRAM to internal buffer 47 */ 48 static void bcm47xx_nvram_copy(void __iomem *nvram_start, size_t res_size) 49 { 50 struct nvram_header __iomem *header = nvram_start; 51 size_t copy_size; 52 53 copy_size = header->len; 54 if (copy_size > res_size) { 55 pr_err("The nvram size according to the header seems to be bigger than the partition on flash\n"); 56 copy_size = res_size; 57 } 58 if (copy_size >= NVRAM_SPACE) { 59 pr_err("nvram on flash (%zu bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n", 60 copy_size, NVRAM_SPACE - 1); 61 copy_size = NVRAM_SPACE - 1; 62 } 63 64 __ioread32_copy(nvram_buf, nvram_start, DIV_ROUND_UP(copy_size, 4)); 65 nvram_buf[NVRAM_SPACE - 1] = '\0'; 66 nvram_len = copy_size; 67 } 68 69 /** 70 * bcm47xx_nvram_find_and_copy - find NVRAM on flash mapping & copy it 71 */ 72 static int bcm47xx_nvram_find_and_copy(void __iomem *flash_start, size_t res_size) 73 { 74 size_t flash_size; 75 size_t offset; 76 int i; 77 78 if (nvram_len) { 79 pr_warn("nvram already initialized\n"); 80 return -EEXIST; 81 } 82 83 /* TODO: when nvram is on nand flash check for bad blocks first. */ 84 85 /* Try every possible flash size and check for NVRAM at its end */ 86 for (flash_size = FLASH_MIN; flash_size <= res_size; flash_size <<= 1) { 87 for (i = 0; i < ARRAY_SIZE(nvram_sizes); i++) { 88 offset = flash_size - nvram_sizes[i]; 89 if (bcm47xx_nvram_is_valid(flash_start + offset)) 90 goto found; 91 } 92 } 93 94 /* Try embedded NVRAM at 4 KB and 1 KB as last resorts */ 95 96 offset = 4096; 97 if (bcm47xx_nvram_is_valid(flash_start + offset)) 98 goto found; 99 100 offset = 1024; 101 if (bcm47xx_nvram_is_valid(flash_start + offset)) 102 goto found; 103 104 pr_err("no nvram found\n"); 105 return -ENXIO; 106 107 found: 108 bcm47xx_nvram_copy(flash_start + offset, res_size - offset); 109 110 return 0; 111 } 112 113 /* 114 * On bcm47xx we need access to the NVRAM very early, so we can't use mtd 115 * subsystem to access flash. We can't even use platform device / driver to 116 * store memory offset. 117 * To handle this we provide following symbol. It's supposed to be called as 118 * soon as we get info about flash device, before any NVRAM entry is needed. 119 */ 120 int bcm47xx_nvram_init_from_mem(u32 base, u32 lim) 121 { 122 void __iomem *iobase; 123 int err; 124 125 iobase = ioremap(base, lim); 126 if (!iobase) 127 return -ENOMEM; 128 129 err = bcm47xx_nvram_find_and_copy(iobase, lim); 130 131 iounmap(iobase); 132 133 return err; 134 } 135 136 static int nvram_init(void) 137 { 138 #ifdef CONFIG_MTD 139 struct mtd_info *mtd; 140 struct nvram_header header; 141 size_t bytes_read; 142 int err; 143 144 mtd = get_mtd_device_nm("nvram"); 145 if (IS_ERR(mtd)) 146 return -ENODEV; 147 148 err = mtd_read(mtd, 0, sizeof(header), &bytes_read, (uint8_t *)&header); 149 if (!err && header.magic == NVRAM_MAGIC && 150 header.len > sizeof(header)) { 151 nvram_len = header.len; 152 if (nvram_len >= NVRAM_SPACE) { 153 pr_err("nvram on flash (%zu bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n", 154 nvram_len, NVRAM_SPACE); 155 nvram_len = NVRAM_SPACE - 1; 156 } 157 158 err = mtd_read(mtd, 0, nvram_len, &nvram_len, 159 (u8 *)nvram_buf); 160 return err; 161 } 162 #endif 163 164 return -ENXIO; 165 } 166 167 int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len) 168 { 169 char *var, *value, *end, *eq; 170 int err; 171 172 if (!name) 173 return -EINVAL; 174 175 if (!nvram_len) { 176 err = nvram_init(); 177 if (err) 178 return err; 179 } 180 181 /* Look for name=value and return value */ 182 var = &nvram_buf[sizeof(struct nvram_header)]; 183 end = nvram_buf + sizeof(nvram_buf); 184 while (var < end && *var) { 185 eq = strchr(var, '='); 186 if (!eq) 187 break; 188 value = eq + 1; 189 if (eq - var == strlen(name) && 190 strncmp(var, name, eq - var) == 0) 191 return snprintf(val, val_len, "%s", value); 192 var = value + strlen(value) + 1; 193 } 194 return -ENOENT; 195 } 196 EXPORT_SYMBOL(bcm47xx_nvram_getenv); 197 198 int bcm47xx_nvram_gpio_pin(const char *name) 199 { 200 int i, err; 201 char nvram_var[] = "gpioXX"; 202 char buf[NVRAM_MAX_GPIO_VALUE_LEN]; 203 204 /* TODO: Optimize it to don't call getenv so many times */ 205 for (i = 0; i < NVRAM_MAX_GPIO_ENTRIES; i++) { 206 err = snprintf(nvram_var, sizeof(nvram_var), "gpio%i", i); 207 if (err <= 0) 208 continue; 209 err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf)); 210 if (err <= 0) 211 continue; 212 if (!strcmp(name, buf)) 213 return i; 214 } 215 return -ENOENT; 216 } 217 EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin); 218 219 char *bcm47xx_nvram_get_contents(size_t *nvram_size) 220 { 221 int err; 222 char *nvram; 223 224 if (!nvram_len) { 225 err = nvram_init(); 226 if (err) 227 return NULL; 228 } 229 230 *nvram_size = nvram_len - sizeof(struct nvram_header); 231 nvram = vmalloc(*nvram_size); 232 if (!nvram) 233 return NULL; 234 memcpy(nvram, &nvram_buf[sizeof(struct nvram_header)], *nvram_size); 235 236 return nvram; 237 } 238 EXPORT_SYMBOL(bcm47xx_nvram_get_contents); 239 240 MODULE_LICENSE("GPL v2"); 241