drivers/firmware/broadcom/bcm47xx_nvram.c

   1 /*
   2  * BCM947xx nvram variable access
   3  *
   4  * Copyright (C) 2005 Broadcom Corporation
   5  * Copyright (C) 2006 Felix Fietkau <nbd@openwrt.org>
   6  * Copyright (C) 2010-2012 Hauke Mehrtens <hauke@hauke-m.de>
   7  *
   8  * This program is free software; you can redistribute  it and/or modify it
   9  * under  the terms of  the GNU General  Public License as published by the
  10  * Free Software Foundation;  either version 2 of the  License, or (at your
  11  * option) any later version.
  12  */
  13
  14 #include <linux/io.h>
  15 #include <linux/types.h>
  16 #include <linux/module.h>
  17 #include <linux/kernel.h>
  18 #include <linux/string.h>
  19 #include <linux/mtd/mtd.h>
  20 #include <linux/bcm47xx_nvram.h>
  21
  22 #define NVRAM_MAGIC                     0x48534C46      /* 'FLSH' */
  23 #define NVRAM_SPACE                     0x10000
  24 #define NVRAM_MAX_GPIO_ENTRIES          32
  25 #define NVRAM_MAX_GPIO_VALUE_LEN        30
  26
  27 #define FLASH_MIN               0x00020000      /* Minimum flash size */
  28
  29 struct nvram_header {
  30         u32 magic;
  31         u32 len;
  32         u32 crc_ver_init;       /* 0:7 crc, 8:15 ver, 16:31 sdram_init */
  33         u32 config_refresh;     /* 0:15 sdram_config, 16:31 sdram_refresh */
  34         u32 config_ncdl;        /* ncdl values for memc */
  35 };
  36
  37 static char nvram_buf[NVRAM_SPACE];
  38 static size_t nvram_len;
  39 static const u32 nvram_sizes[] = {0x8000, 0xF000, 0x10000};
  40
  41 static u32 find_nvram_size(void __iomem *end)
  42 {
  43         struct nvram_header __iomem *header;
  44         int i;
  45
  46         for (i = 0; i < ARRAY_SIZE(nvram_sizes); i++) {
  47                 header = (struct nvram_header *)(end - nvram_sizes[i]);
  48                 if (header->magic == NVRAM_MAGIC)
  49                         return nvram_sizes[i];
  50         }
  51
  52         return 0;
  53 }
  54
  55 /* Probe for NVRAM header */
  56 static int nvram_find_and_copy(void __iomem *iobase, u32 lim)
  57 {
  58         struct nvram_header __iomem *header;
  59         int i;
  60         u32 off;
  61         u32 *src, *dst;
  62         u32 size;
  63
  64         if (nvram_len) {
  65                 pr_warn("nvram already initialized\n");
  66                 return -EEXIST;
  67         }
  68
  69         /* TODO: when nvram is on nand flash check for bad blocks first. */
  70         off = FLASH_MIN;
  71         while (off <= lim) {
  72                 /* Windowed flash access */
  73                 size = find_nvram_size(iobase + off);
  74                 if (size) {
  75                         header = (struct nvram_header *)(iobase + off - size);
  76                         goto found;
  77                 }
  78                 off <<= 1;
  79         }
  80
  81         /* Try embedded NVRAM at 4 KB and 1 KB as last resorts */
  82         header = (struct nvram_header *)(iobase + 4096);
  83         if (header->magic == NVRAM_MAGIC) {
  84                 size = NVRAM_SPACE;
  85                 goto found;
  86         }
  87
  88         header = (struct nvram_header *)(iobase + 1024);
  89         if (header->magic == NVRAM_MAGIC) {
  90                 size = NVRAM_SPACE;
  91                 goto found;
  92         }
  93
  94         pr_err("no nvram found\n");
  95         return -ENXIO;
  96
  97 found:
  98         src = (u32 *)header;
  99         dst = (u32 *)nvram_buf;
 100         for (i = 0; i < sizeof(struct nvram_header); i += 4)
 101                 *dst++ = __raw_readl(src++);
 102         header = (struct nvram_header *)nvram_buf;
 103         nvram_len = header->len;
 104         if (nvram_len > size) {
 105                 pr_err("The nvram size according to the header seems to be bigger than the partition on flash\n");
 106                 nvram_len = size;
 107         }
 108         if (nvram_len >= NVRAM_SPACE) {
 109                 pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
 110                        header->len, NVRAM_SPACE - 1);
 111                 nvram_len = NVRAM_SPACE - 1;
 112         }
 113         /* proceed reading data after header */
 114         for (; i < nvram_len; i += 4)
 115                 *dst++ = readl(src++);
 116         nvram_buf[NVRAM_SPACE - 1] = '\0';
 117
 118         return 0;
 119 }
 120
 121 /*
 122  * On bcm47xx we need access to the NVRAM very early, so we can't use mtd
 123  * subsystem to access flash. We can't even use platform device / driver to
 124  * store memory offset.
 125  * To handle this we provide following symbol. It's supposed to be called as
 126  * soon as we get info about flash device, before any NVRAM entry is needed.
 127  */
 128 int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
 129 {
 130         void __iomem *iobase;
 131         int err;
 132
 133         iobase = ioremap_nocache(base, lim);
 134         if (!iobase)
 135                 return -ENOMEM;
 136
 137         err = nvram_find_and_copy(iobase, lim);
 138
 139         iounmap(iobase);
 140
 141         return err;
 142 }
 143
 144 static int nvram_init(void)
 145 {
 146 #ifdef CONFIG_MTD
 147         struct mtd_info *mtd;
 148         struct nvram_header header;
 149         size_t bytes_read;
 150         int err;
 151
 152         mtd = get_mtd_device_nm("nvram");
 153         if (IS_ERR(mtd))
 154                 return -ENODEV;
 155
 156         err = mtd_read(mtd, 0, sizeof(header), &bytes_read, (uint8_t *)&header);
 157         if (!err && header.magic == NVRAM_MAGIC &&
 158             header.len > sizeof(header)) {
 159                 nvram_len = header.len;
 160                 if (nvram_len >= NVRAM_SPACE) {
 161                         pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
 162                                 header.len, NVRAM_SPACE);
 163                         nvram_len = NVRAM_SPACE - 1;
 164                 }
 165
 166                 err = mtd_read(mtd, 0, nvram_len, &nvram_len,
 167                                (u8 *)nvram_buf);
 168                 return err;
 169         }
 170 #endif
 171
 172         return -ENXIO;
 173 }
 174
 175 int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len)
 176 {
 177         char *var, *value, *end, *eq;
 178         int err;
 179
 180         if (!name)
 181                 return -EINVAL;
 182
 183         if (!nvram_len) {
 184                 err = nvram_init();
 185                 if (err)
 186                         return err;
 187         }
 188
 189         /* Look for name=value and return value */
 190         var = &nvram_buf[sizeof(struct nvram_header)];
 191         end = nvram_buf + sizeof(nvram_buf);
 192         while (var < end && *var) {
 193                 eq = strchr(var, '=');
 194                 if (!eq)
 195                         break;
 196                 value = eq + 1;
 197                 if (eq - var == strlen(name) &&
 198                     strncmp(var, name, eq - var) == 0)
 199                         return snprintf(val, val_len, "%s", value);
 200                 var = value + strlen(value) + 1;
 201         }
 202         return -ENOENT;
 203 }
 204 EXPORT_SYMBOL(bcm47xx_nvram_getenv);
 205
 206 int bcm47xx_nvram_gpio_pin(const char *name)
 207 {
 208         int i, err;
 209         char nvram_var[] = "gpioXX";
 210         char buf[NVRAM_MAX_GPIO_VALUE_LEN];
 211
 212         /* TODO: Optimize it to don't call getenv so many times */
 213         for (i = 0; i < NVRAM_MAX_GPIO_ENTRIES; i++) {
 214                 err = snprintf(nvram_var, sizeof(nvram_var), "gpio%i", i);
 215                 if (err <= 0)
 216                         continue;
 217                 err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf));
 218                 if (err <= 0)
 219                         continue;
 220                 if (!strcmp(name, buf))
 221                         return i;
 222         }
 223         return -ENOENT;
 224 }
 225 EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);
 226
 227 char *bcm47xx_nvram_get_contents(size_t *nvram_size)
 228 {
 229         int err;
 230         char *nvram;
 231
 232         if (!nvram_len) {
 233                 err = nvram_init();
 234                 if (err)
 235                         return NULL;
 236         }
 237
 238         *nvram_size = nvram_len - sizeof(struct nvram_header);
 239         nvram = vmalloc(*nvram_size);
 240         if (!nvram)
 241                 return NULL;
 242         memcpy(nvram, &nvram_buf[sizeof(struct nvram_header)], *nvram_size);
 243
 244         return nvram;
 245 }
 246 EXPORT_SYMBOL(bcm47xx_nvram_get_contents);
 247
 248 MODULE_LICENSE("GPL v2");