drivers/firmware/broadcom/bcm47xx_nvram.c

   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 int bcm47xx_nvram_init_from_iomem(void __iomem *nvram_start, size_t res_size)
 114 {
 115         if (nvram_len) {
 116                 pr_warn("nvram already initialized\n");
 117                 return -EEXIST;
 118         }
 119
 120         if (!bcm47xx_nvram_is_valid(nvram_start)) {
 121                 pr_err("No valid NVRAM found\n");
 122                 return -ENOENT;
 123         }
 124
 125         bcm47xx_nvram_copy(nvram_start, res_size);
 126
 127         return 0;
 128 }
 129 EXPORT_SYMBOL_GPL(bcm47xx_nvram_init_from_iomem);
 130
 131 /*
 132  * On bcm47xx we need access to the NVRAM very early, so we can't use mtd
 133  * subsystem to access flash. We can't even use platform device / driver to
 134  * store memory offset.
 135  * To handle this we provide following symbol. It's supposed to be called as
 136  * soon as we get info about flash device, before any NVRAM entry is needed.
 137  */
 138 int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
 139 {
 140         void __iomem *iobase;
 141         int err;
 142
 143         iobase = ioremap(base, lim);
 144         if (!iobase)
 145                 return -ENOMEM;
 146
 147         err = bcm47xx_nvram_find_and_copy(iobase, lim);
 148
 149         iounmap(iobase);
 150
 151         return err;
 152 }
 153
 154 static int nvram_init(void)
 155 {
 156 #ifdef CONFIG_MTD
 157         struct mtd_info *mtd;
 158         struct nvram_header header;
 159         size_t bytes_read;
 160         int err;
 161
 162         mtd = get_mtd_device_nm("nvram");
 163         if (IS_ERR(mtd))
 164                 return -ENODEV;
 165
 166         err = mtd_read(mtd, 0, sizeof(header), &bytes_read, (uint8_t *)&header);
 167         if (!err && header.magic == NVRAM_MAGIC &&
 168             header.len > sizeof(header)) {
 169                 nvram_len = header.len;
 170                 if (nvram_len >= NVRAM_SPACE) {
 171                         pr_err("nvram on flash (%zu bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
 172                                 nvram_len, NVRAM_SPACE);
 173                         nvram_len = NVRAM_SPACE - 1;
 174                 }
 175
 176                 err = mtd_read(mtd, 0, nvram_len, &nvram_len,
 177                                (u8 *)nvram_buf);
 178                 return err;
 179         }
 180 #endif
 181
 182         return -ENXIO;
 183 }
 184
 185 int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len)
 186 {
 187         char *var, *value, *end, *eq;
 188         int err;
 189
 190         if (!name)
 191                 return -EINVAL;
 192
 193         if (!nvram_len) {
 194                 err = nvram_init();
 195                 if (err)
 196                         return err;
 197         }
 198
 199         /* Look for name=value and return value */
 200         var = &nvram_buf[sizeof(struct nvram_header)];
 201         end = nvram_buf + sizeof(nvram_buf);
 202         while (var < end && *var) {
 203                 eq = strchr(var, '=');
 204                 if (!eq)
 205                         break;
 206                 value = eq + 1;
 207                 if (eq - var == strlen(name) &&
 208                     strncmp(var, name, eq - var) == 0)
 209                         return snprintf(val, val_len, "%s", value);
 210                 var = value + strlen(value) + 1;
 211         }
 212         return -ENOENT;
 213 }
 214 EXPORT_SYMBOL(bcm47xx_nvram_getenv);
 215
 216 int bcm47xx_nvram_gpio_pin(const char *name)
 217 {
 218         int i, err;
 219         char nvram_var[] = "gpioXX";
 220         char buf[NVRAM_MAX_GPIO_VALUE_LEN];
 221
 222         /* TODO: Optimize it to don't call getenv so many times */
 223         for (i = 0; i < NVRAM_MAX_GPIO_ENTRIES; i++) {
 224                 err = snprintf(nvram_var, sizeof(nvram_var), "gpio%i", i);
 225                 if (err <= 0)
 226                         continue;
 227                 err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf));
 228                 if (err <= 0)
 229                         continue;
 230                 if (!strcmp(name, buf))
 231                         return i;
 232         }
 233         return -ENOENT;
 234 }
 235 EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);
 236
 237 char *bcm47xx_nvram_get_contents(size_t *nvram_size)
 238 {
 239         int err;
 240         char *nvram;
 241
 242         if (!nvram_len) {
 243                 err = nvram_init();
 244                 if (err)
 245                         return NULL;
 246         }
 247
 248         *nvram_size = nvram_len - sizeof(struct nvram_header);
 249         nvram = vmalloc(*nvram_size);
 250         if (!nvram)
 251                 return NULL;
 252         memcpy(nvram, &nvram_buf[sizeof(struct nvram_header)], *nvram_size);
 253
 254         return nvram;
 255 }
 256 EXPORT_SYMBOL(bcm47xx_nvram_get_contents);
 257