arch/mips/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/types.h>
  15 #include <linux/module.h>
  16 #include <linux/kernel.h>
  17 #include <linux/string.h>
  18 #include <linux/mtd/mtd.h>
  19 #include <bcm47xx_nvram.h>
  20
  21 #define NVRAM_MAGIC             0x48534C46      /* 'FLSH' */
  22 #define NVRAM_SPACE             0x8000
  23
  24 #define FLASH_MIN               0x00020000      /* Minimum flash size */
  25
  26 struct nvram_header {
  27         u32 magic;
  28         u32 len;
  29         u32 crc_ver_init;       /* 0:7 crc, 8:15 ver, 16:31 sdram_init */
  30         u32 config_refresh;     /* 0:15 sdram_config, 16:31 sdram_refresh */
  31         u32 config_ncdl;        /* ncdl values for memc */
  32 };
  33
  34 static char nvram_buf[NVRAM_SPACE];
  35 static const u32 nvram_sizes[] = {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         int i;
  56         u32 off;
  57         u32 *src, *dst;
  58         u32 size;
  59
  60         if (nvram_buf[0]) {
  61                 pr_warn("nvram already initialized\n");
  62                 return -EEXIST;
  63         }
  64
  65         /* TODO: when nvram is on nand flash check for bad blocks first. */
  66         off = FLASH_MIN;
  67         while (off <= lim) {
  68                 /* Windowed flash access */
  69                 size = find_nvram_size(iobase + off);
  70                 if (size) {
  71                         header = (struct nvram_header *)(iobase + off - size);
  72                         goto found;
  73                 }
  74                 off <<= 1;
  75         }
  76
  77         /* Try embedded NVRAM at 4 KB and 1 KB as last resorts */
  78         header = (struct nvram_header *)(iobase + 4096);
  79         if (header->magic == NVRAM_MAGIC) {
  80                 size = NVRAM_SPACE;
  81                 goto found;
  82         }
  83
  84         header = (struct nvram_header *)(iobase + 1024);
  85         if (header->magic == NVRAM_MAGIC) {
  86                 size = NVRAM_SPACE;
  87                 goto found;
  88         }
  89
  90         pr_err("no nvram found\n");
  91         return -ENXIO;
  92
  93 found:
  94
  95         if (header->len > size)
  96                 pr_err("The nvram size accoridng to the header seems to be bigger than the partition on flash\n");
  97         if (header->len > NVRAM_SPACE)
  98                 pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
  99                        header->len, NVRAM_SPACE);
 100
 101         src = (u32 *) header;
 102         dst = (u32 *) nvram_buf;
 103         for (i = 0; i < sizeof(struct nvram_header); i += 4)
 104                 *dst++ = *src++;
 105         for (; i < header->len && i < NVRAM_SPACE && i < size; i += 4)
 106                 *dst++ = le32_to_cpu(*src++);
 107         memset(dst, 0x0, NVRAM_SPACE - i);
 108
 109         return 0;
 110 }
 111
 112 /*
 113  * On bcm47xx we need access to the NVRAM very early, so we can't use mtd
 114  * subsystem to access flash. We can't even use platform device / driver to
 115  * store memory offset.
 116  * To handle this we provide following symbol. It's supposed to be called as
 117  * soon as we get info about flash device, before any NVRAM entry is needed.
 118  */
 119 int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
 120 {
 121         void __iomem *iobase;
 122         int err;
 123
 124         iobase = ioremap_nocache(base, lim);
 125         if (!iobase)
 126                 return -ENOMEM;
 127
 128         err = nvram_find_and_copy(iobase, lim);
 129
 130         iounmap(iobase);
 131
 132         return err;
 133 }
 134
 135 static int nvram_init(void)
 136 {
 137 #ifdef CONFIG_MTD
 138         struct mtd_info *mtd;
 139         struct nvram_header header;
 140         size_t bytes_read;
 141         int err, i;
 142
 143         mtd = get_mtd_device_nm("nvram");
 144         if (IS_ERR(mtd))
 145                 return -ENODEV;
 146
 147         for (i = 0; i < ARRAY_SIZE(nvram_sizes); i++) {
 148                 loff_t from = mtd->size - nvram_sizes[i];
 149
 150                 if (from < 0)
 151                         continue;
 152
 153                 err = mtd_read(mtd, from, sizeof(header), &bytes_read,
 154                                (uint8_t *)&header);
 155                 if (!err && header.magic == NVRAM_MAGIC) {
 156                         u8 *dst = (uint8_t *)nvram_buf;
 157                         size_t len = header.len;
 158
 159                         if (header.len > NVRAM_SPACE) {
 160                                 pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
 161                                        header.len, NVRAM_SPACE);
 162                                 len = NVRAM_SPACE;
 163                         }
 164
 165                         err = mtd_read(mtd, from, len, &bytes_read, dst);
 166                         if (err)
 167                                 return err;
 168                         memset(dst + bytes_read, 0x0, NVRAM_SPACE - bytes_read);
 169
 170                         return 0;
 171                 }
 172         }
 173 #endif
 174
 175         return -ENXIO;
 176 }
 177
 178 int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len)
 179 {
 180         char *var, *value, *end, *eq;
 181         int err;
 182
 183         if (!name)
 184                 return -EINVAL;
 185
 186         if (!nvram_buf[0]) {
 187                 err = nvram_init();
 188                 if (err)
 189                         return err;
 190         }
 191
 192         /* Look for name=value and return value */
 193         var = &nvram_buf[sizeof(struct nvram_header)];
 194         end = nvram_buf + sizeof(nvram_buf) - 2;
 195         end[0] = end[1] = '\0';
 196         for (; *var; var = value + strlen(value) + 1) {
 197                 eq = strchr(var, '=');
 198                 if (!eq)
 199                         break;
 200                 value = eq + 1;
 201                 if ((eq - var) == strlen(name) &&
 202                         strncmp(var, name, (eq - var)) == 0) {
 203                         return snprintf(val, val_len, "%s", value);
 204                 }
 205         }
 206         return -ENOENT;
 207 }
 208 EXPORT_SYMBOL(bcm47xx_nvram_getenv);
 209
 210 int bcm47xx_nvram_gpio_pin(const char *name)
 211 {
 212         int i, err;
 213         char nvram_var[10];
 214         char buf[30];
 215
 216         for (i = 0; i < 32; i++) {
 217                 err = snprintf(nvram_var, sizeof(nvram_var), "gpio%i", i);
 218                 if (err <= 0)
 219                         continue;
 220                 err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf));
 221                 if (err <= 0)
 222                         continue;
 223                 if (!strcmp(name, buf))
 224                         return i;
 225         }
 226         return -ENOENT;
 227 }
 228 EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);