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 static u32 find_nvram_size(void __iomem *end)
  38 {
  39         struct nvram_header __iomem *header;
  40         int i;
  41
  42         for (i = 0; i < ARRAY_SIZE(nvram_sizes); i++) {
  43                 header = (struct nvram_header *)(end - nvram_sizes[i]);
  44                 if (header->magic == NVRAM_MAGIC)
  45                         return nvram_sizes[i];
  46         }
  47
  48         return 0;
  49 }
  50
  51 /* Probe for NVRAM header */
  52 static int nvram_find_and_copy(void __iomem *iobase, u32 lim)
  53 {
  54         struct nvram_header __iomem *header;
  55         u32 off;
  56         u32 size;
  57
  58         if (nvram_len) {
  59                 pr_warn("nvram already initialized\n");
  60                 return -EEXIST;
  61         }
  62
  63         /* TODO: when nvram is on nand flash check for bad blocks first. */
  64         off = FLASH_MIN;
  65         while (off <= lim) {
  66                 /* Windowed flash access */
  67                 size = find_nvram_size(iobase + off);
  68                 if (size) {
  69                         header = (struct nvram_header *)(iobase + off - size);
  70                         goto found;
  71                 }
  72                 off <<= 1;
  73         }
  74
  75         /* Try embedded NVRAM at 4 KB and 1 KB as last resorts */
  76         header = (struct nvram_header *)(iobase + 4096);
  77         if (header->magic == NVRAM_MAGIC) {
  78                 size = NVRAM_SPACE;
  79                 goto found;
  80         }
  81
  82         header = (struct nvram_header *)(iobase + 1024);
  83         if (header->magic == NVRAM_MAGIC) {
  84                 size = NVRAM_SPACE;
  85                 goto found;
  86         }
  87
  88         pr_err("no nvram found\n");
  89         return -ENXIO;
  90
  91 found:
  92         __ioread32_copy(nvram_buf, header, sizeof(*header) / 4);
  93         nvram_len = ((struct nvram_header *)(nvram_buf))->len;
  94         if (nvram_len > size) {
  95                 pr_err("The nvram size according to the header seems to be bigger than the partition on flash\n");
  96                 nvram_len = size;
  97         }
  98         if (nvram_len >= NVRAM_SPACE) {
  99                 pr_err("nvram on flash (%zu bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
 100                        nvram_len, NVRAM_SPACE - 1);
 101                 nvram_len = NVRAM_SPACE - 1;
 102         }
 103         /* proceed reading data after header */
 104         __ioread32_copy(nvram_buf + sizeof(*header), header + 1,
 105                         DIV_ROUND_UP(nvram_len, 4));
 106         nvram_buf[NVRAM_SPACE - 1] = '\0';
 107
 108         return 0;
 109 }
 110
 111 /*
 112  * On bcm47xx we need access to the NVRAM very early, so we can't use mtd
 113  * subsystem to access flash. We can't even use platform device / driver to
 114  * store memory offset.
 115  * To handle this we provide following symbol. It's supposed to be called as
 116  * soon as we get info about flash device, before any NVRAM entry is needed.
 117  */
 118 int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
 119 {
 120         void __iomem *iobase;
 121         int err;
 122
 123         iobase = ioremap(base, lim);
 124         if (!iobase)
 125                 return -ENOMEM;
 126
 127         err = nvram_find_and_copy(iobase, lim);
 128
 129         iounmap(iobase);
 130
 131         return err;
 132 }
 133
 134 static int nvram_init(void)
 135 {
 136 #ifdef CONFIG_MTD
 137         struct mtd_info *mtd;
 138         struct nvram_header header;
 139         size_t bytes_read;
 140         int err;
 141
 142         mtd = get_mtd_device_nm("nvram");
 143         if (IS_ERR(mtd))
 144                 return -ENODEV;
 145
 146         err = mtd_read(mtd, 0, sizeof(header), &bytes_read, (uint8_t *)&header);
 147         if (!err && header.magic == NVRAM_MAGIC &&
 148             header.len > sizeof(header)) {
 149                 nvram_len = header.len;
 150                 if (nvram_len >= NVRAM_SPACE) {
 151                         pr_err("nvram on flash (%zu bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
 152                                 nvram_len, NVRAM_SPACE);
 153                         nvram_len = NVRAM_SPACE - 1;
 154                 }
 155
 156                 err = mtd_read(mtd, 0, nvram_len, &nvram_len,
 157                                (u8 *)nvram_buf);
 158                 return err;
 159         }
 160 #endif
 161
 162         return -ENXIO;
 163 }
 164
 165 int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len)
 166 {
 167         char *var, *value, *end, *eq;
 168         int err;
 169
 170         if (!name)
 171                 return -EINVAL;
 172
 173         if (!nvram_len) {
 174                 err = nvram_init();
 175                 if (err)
 176                         return err;
 177         }
 178
 179         /* Look for name=value and return value */
 180         var = &nvram_buf[sizeof(struct nvram_header)];
 181         end = nvram_buf + sizeof(nvram_buf);
 182         while (var < end && *var) {
 183                 eq = strchr(var, '=');
 184                 if (!eq)
 185                         break;
 186                 value = eq + 1;
 187                 if (eq - var == strlen(name) &&
 188                     strncmp(var, name, eq - var) == 0)
 189                         return snprintf(val, val_len, "%s", value);
 190                 var = value + strlen(value) + 1;
 191         }
 192         return -ENOENT;
 193 }
 194 EXPORT_SYMBOL(bcm47xx_nvram_getenv);
 195
 196 int bcm47xx_nvram_gpio_pin(const char *name)
 197 {
 198         int i, err;
 199         char nvram_var[] = "gpioXX";
 200         char buf[NVRAM_MAX_GPIO_VALUE_LEN];
 201
 202         /* TODO: Optimize it to don't call getenv so many times */
 203         for (i = 0; i < NVRAM_MAX_GPIO_ENTRIES; i++) {
 204                 err = snprintf(nvram_var, sizeof(nvram_var), "gpio%i", i);
 205                 if (err <= 0)
 206                         continue;
 207                 err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf));
 208                 if (err <= 0)
 209                         continue;
 210                 if (!strcmp(name, buf))
 211                         return i;
 212         }
 213         return -ENOENT;
 214 }
 215 EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);
 216
 217 char *bcm47xx_nvram_get_contents(size_t *nvram_size)
 218 {
 219         int err;
 220         char *nvram;
 221
 222         if (!nvram_len) {
 223                 err = nvram_init();
 224                 if (err)
 225                         return NULL;
 226         }
 227
 228         *nvram_size = nvram_len - sizeof(struct nvram_header);
 229         nvram = vmalloc(*nvram_size);
 230         if (!nvram)
 231                 return NULL;
 232         memcpy(nvram, &nvram_buf[sizeof(struct nvram_header)], *nvram_size);
 233
 234         return nvram;
 235 }
 236 EXPORT_SYMBOL(bcm47xx_nvram_get_contents);
 237
 238 MODULE_LICENSE("GPL v2");