linux/drivers/firmware/broadcom/bcm47xx_nvram.c
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   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
  25struct 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
  33static char nvram_buf[NVRAM_SPACE];
  34static size_t nvram_len;
  35static const u32 nvram_sizes[] = {0x6000, 0x8000, 0xF000, 0x10000};
  36
  37/**
  38 * bcm47xx_nvram_is_valid - check for a valid NVRAM at specified memory
  39 */
  40static 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 */
  48static 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 */
  72static 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
 107found:
 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 */
 120int 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
 136static 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
 167int 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}
 196EXPORT_SYMBOL(bcm47xx_nvram_getenv);
 197
 198int 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}
 217EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);
 218
 219char *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}
 238EXPORT_SYMBOL(bcm47xx_nvram_get_contents);
 239
 240MODULE_LICENSE("GPL v2");
 241