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/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 const u32 nvram_sizes[] = {0x8000, 0xF000, 0x10000};
  39
  40 static u32 find_nvram_size(void __iomem *end)
  41 {
  42         struct nvram_header __iomem *header;
  43         int i;
  44
  45         for (i = 0; i < ARRAY_SIZE(nvram_sizes); i++) {
  46                 header = (struct nvram_header *)(end - nvram_sizes[i]);
  47                 if (header->magic == NVRAM_MAGIC)
  48                         return nvram_sizes[i];
  49         }
  50
  51         return 0;
  52 }
  53
  54 /* Probe for NVRAM header */
  55 static int nvram_find_and_copy(void __iomem *iobase, u32 lim)
  56 {
  57         struct nvram_header __iomem *header;
  58         int i;
  59         u32 off;
  60         u32 *src, *dst;
  61         u32 size;
  62
  63         if (nvram_buf[0]) {
  64                 pr_warn("nvram already initialized\n");
  65                 return -EEXIST;
  66         }
  67
  68         /* TODO: when nvram is on nand flash check for bad blocks first. */
  69         off = FLASH_MIN;
  70         while (off <= lim) {
  71                 /* Windowed flash access */
  72                 size = find_nvram_size(iobase + off);
  73                 if (size) {
  74                         header = (struct nvram_header *)(iobase + off - size);
  75                         goto found;
  76                 }
  77                 off <<= 1;
  78         }
  79
  80         /* Try embedded NVRAM at 4 KB and 1 KB as last resorts */
  81         header = (struct nvram_header *)(iobase + 4096);
  82         if (header->magic == NVRAM_MAGIC) {
  83                 size = NVRAM_SPACE;
  84                 goto found;
  85         }
  86
  87         header = (struct nvram_header *)(iobase + 1024);
  88         if (header->magic == NVRAM_MAGIC) {
  89                 size = NVRAM_SPACE;
  90                 goto found;
  91         }
  92
  93         pr_err("no nvram found\n");
  94         return -ENXIO;
  95
  96 found:
  97         if (header->len > size)
  98                 pr_err("The nvram size accoridng to the header seems to be bigger than the partition on flash\n");
  99         if (header->len > NVRAM_SPACE)
 100                 pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
 101                        header->len, NVRAM_SPACE);
 102
 103         src = (u32 *)header;
 104         dst = (u32 *)nvram_buf;
 105         for (i = 0; i < sizeof(struct nvram_header); i += 4)
 106                 *dst++ = __raw_readl(src++);
 107         for (; i < header->len && i < NVRAM_SPACE && i < size; i += 4)
 108                 *dst++ = readl(src++);
 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  */
 120 int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
 121 {
 122         void __iomem *iobase;
 123         int err;
 124
 125         iobase = ioremap_nocache(base, lim);
 126         if (!iobase)
 127                 return -ENOMEM;
 128
 129         err = nvram_find_and_copy(iobase, lim);
 130
 131         iounmap(iobase);
 132
 133         return err;
 134 }
 135
 136 static 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                 u8 *dst = (uint8_t *)nvram_buf;
 151                 size_t len = header.len;
 152
 153                 if (header.len > NVRAM_SPACE) {
 154                         pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
 155                                 header.len, NVRAM_SPACE);
 156                         len = NVRAM_SPACE;
 157                 }
 158
 159                 err = mtd_read(mtd, 0, len, &bytes_read, dst);
 160                 if (err)
 161                         return err;
 162
 163                 return 0;
 164         }
 165 #endif
 166
 167         return -ENXIO;
 168 }
 169
 170 int bcm47xx_nvram_getenv(const char *name, char *val, size_t val_len)
 171 {
 172         char *var, *value, *end, *eq;
 173         int data_left, err;
 174
 175         if (!name)
 176                 return -EINVAL;
 177
 178         if (!nvram_buf[0]) {
 179                 err = nvram_init();
 180                 if (err)
 181                         return err;
 182         }
 183
 184         /* Look for name=value and return value */
 185         var = &nvram_buf[sizeof(struct nvram_header)];
 186         end = nvram_buf + sizeof(nvram_buf) - 2;
 187         end[0] = '\0';
 188         end[1] = '\0';
 189         for (; *var; var = value + strlen(value) + 1) {
 190                 data_left = end - var;
 191
 192                 eq = strnchr(var, data_left, '=');
 193                 if (!eq)
 194                         break;
 195                 value = eq + 1;
 196                 if (eq - var == strlen(name) &&
 197                     strncmp(var, name, eq - var) == 0)
 198                         return snprintf(val, val_len, "%s", value);
 199         }
 200         return -ENOENT;
 201 }
 202 EXPORT_SYMBOL(bcm47xx_nvram_getenv);
 203
 204 int bcm47xx_nvram_gpio_pin(const char *name)
 205 {
 206         int i, err;
 207         char nvram_var[] = "gpioXX";
 208         char buf[NVRAM_MAX_GPIO_VALUE_LEN];
 209
 210         /* TODO: Optimize it to don't call getenv so many times */
 211         for (i = 0; i < NVRAM_MAX_GPIO_ENTRIES; i++) {
 212                 err = snprintf(nvram_var, sizeof(nvram_var), "gpio%i", i);
 213                 if (err <= 0)
 214                         continue;
 215                 err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf));
 216                 if (err <= 0)
 217                         continue;
 218                 if (!strcmp(name, buf))
 219                         return i;
 220         }
 221         return -ENOENT;
 222 }
 223 EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);