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         u32 off;
  60         u32 size;
  61
  62         if (nvram_len) {
  63                 pr_warn("nvram already initialized\n");
  64                 return -EEXIST;
  65         }
  66
  67         /* TODO: when nvram is on nand flash check for bad blocks first. */
  68         off = FLASH_MIN;
  69         while (off <= lim) {
  70                 /* Windowed flash access */
  71                 size = find_nvram_size(iobase + off);
  72                 if (size) {
  73                         header = (struct nvram_header *)(iobase + off - size);
  74                         goto found;
  75                 }
  76                 off <<= 1;
  77         }
  78
  79         /* Try embedded NVRAM at 4 KB and 1 KB as last resorts */
  80         header = (struct nvram_header *)(iobase + 4096);
  81         if (header->magic == NVRAM_MAGIC) {
  82                 size = NVRAM_SPACE;
  83                 goto found;
  84         }
  85
  86         header = (struct nvram_header *)(iobase + 1024);
  87         if (header->magic == NVRAM_MAGIC) {
  88                 size = NVRAM_SPACE;
  89                 goto found;
  90         }
  91
  92         pr_err("no nvram found\n");
  93         return -ENXIO;
  94
  95 found:
  96         __ioread32_copy(nvram_buf, header, sizeof(*header) / 4);
  97         nvram_len = ((struct nvram_header *)(nvram_buf))->len;
  98         if (nvram_len > size) {
  99                 pr_err("The nvram size according to the header seems to be bigger than the partition on flash\n");
 100                 nvram_len = size;
 101         }
 102         if (nvram_len >= NVRAM_SPACE) {
 103                 pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
 104                        nvram_len, NVRAM_SPACE - 1);
 105                 nvram_len = NVRAM_SPACE - 1;
 106         }
 107         /* proceed reading data after header */
 108         __ioread32_copy(nvram_buf + sizeof(*header), header + 1,
 109                         DIV_ROUND_UP(nvram_len, 4));
 110         nvram_buf[NVRAM_SPACE - 1] = '\0';
 111
 112         return 0;
 113 }
 114
 115 /*
 116  * On bcm47xx we need access to the NVRAM very early, so we can't use mtd
 117  * subsystem to access flash. We can't even use platform device / driver to
 118  * store memory offset.
 119  * To handle this we provide following symbol. It's supposed to be called as
 120  * soon as we get info about flash device, before any NVRAM entry is needed.
 121  */
 122 int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
 123 {
 124         void __iomem *iobase;
 125         int err;
 126
 127         iobase = ioremap_nocache(base, lim);
 128         if (!iobase)
 129                 return -ENOMEM;
 130
 131         err = nvram_find_and_copy(iobase, lim);
 132
 133         iounmap(iobase);
 134
 135         return err;
 136 }
 137
 138 static int nvram_init(void)
 139 {
 140 #ifdef CONFIG_MTD
 141         struct mtd_info *mtd;
 142         struct nvram_header header;
 143         size_t bytes_read;
 144         int err;
 145
 146         mtd = get_mtd_device_nm("nvram");
 147         if (IS_ERR(mtd))
 148                 return -ENODEV;
 149
 150         err = mtd_read(mtd, 0, sizeof(header), &bytes_read, (uint8_t *)&header);
 151         if (!err && header.magic == NVRAM_MAGIC &&
 152             header.len > sizeof(header)) {
 153                 nvram_len = header.len;
 154                 if (nvram_len >= NVRAM_SPACE) {
 155                         pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
 156                                 header.len, NVRAM_SPACE);
 157                         nvram_len = NVRAM_SPACE - 1;
 158                 }
 159
 160                 err = mtd_read(mtd, 0, nvram_len, &nvram_len,
 161                                (u8 *)nvram_buf);
 162                 return err;
 163         }
 164 #endif
 165
 166         return -ENXIO;
 167 }
 168
 169 int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len)
 170 {
 171         char *var, *value, *end, *eq;
 172         int err;
 173
 174         if (!name)
 175                 return -EINVAL;
 176
 177         if (!nvram_len) {
 178                 err = nvram_init();
 179                 if (err)
 180                         return err;
 181         }
 182
 183         /* Look for name=value and return value */
 184         var = &nvram_buf[sizeof(struct nvram_header)];
 185         end = nvram_buf + sizeof(nvram_buf);
 186         while (var < end && *var) {
 187                 eq = strchr(var, '=');
 188                 if (!eq)
 189                         break;
 190                 value = eq + 1;
 191                 if (eq - var == strlen(name) &&
 192                     strncmp(var, name, eq - var) == 0)
 193                         return snprintf(val, val_len, "%s", value);
 194                 var = value + strlen(value) + 1;
 195         }
 196         return -ENOENT;
 197 }
 198 EXPORT_SYMBOL(bcm47xx_nvram_getenv);
 199
 200 int bcm47xx_nvram_gpio_pin(const char *name)
 201 {
 202         int i, err;
 203         char nvram_var[] = "gpioXX";
 204         char buf[NVRAM_MAX_GPIO_VALUE_LEN];
 205
 206         /* TODO: Optimize it to don't call getenv so many times */
 207         for (i = 0; i < NVRAM_MAX_GPIO_ENTRIES; i++) {
 208                 err = snprintf(nvram_var, sizeof(nvram_var), "gpio%i", i);
 209                 if (err <= 0)
 210                         continue;
 211                 err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf));
 212                 if (err <= 0)
 213                         continue;
 214                 if (!strcmp(name, buf))
 215                         return i;
 216         }
 217         return -ENOENT;
 218 }
 219 EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);
 220
 221 char *bcm47xx_nvram_get_contents(size_t *nvram_size)
 222 {
 223         int err;
 224         char *nvram;
 225
 226         if (!nvram_len) {
 227                 err = nvram_init();
 228                 if (err)
 229                         return NULL;
 230         }
 231
 232         *nvram_size = nvram_len - sizeof(struct nvram_header);
 233         nvram = vmalloc(*nvram_size);
 234         if (!nvram)
 235                 return NULL;
 236         memcpy(nvram, &nvram_buf[sizeof(struct nvram_header)], *nvram_size);
 237
 238         return nvram;
 239 }
 240 EXPORT_SYMBOL(bcm47xx_nvram_get_contents);
 241
 242 MODULE_LICENSE("GPL v2");