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/ssb/ssb.h>
  17 #include <linux/kernel.h>
  18 #include <linux/string.h>
  19 #include <asm/addrspace.h>
  20 #include <bcm47xx_nvram.h>
  21 #include <asm/mach-bcm47xx/bcm47xx.h>
  22
  23 static char nvram_buf[NVRAM_SPACE];
  24 static const u32 nvram_sizes[] = {0x8000, 0xF000, 0x10000};
  25
  26 static u32 find_nvram_size(void __iomem *end)
  27 {
  28         struct nvram_header __iomem *header;
  29         int i;
  30
  31         for (i = 0; i < ARRAY_SIZE(nvram_sizes); i++) {
  32                 header = (struct nvram_header *)(end - nvram_sizes[i]);
  33                 if (header->magic == NVRAM_HEADER)
  34                         return nvram_sizes[i];
  35         }
  36
  37         return 0;
  38 }
  39
  40 /* Probe for NVRAM header */
  41 static int nvram_find_and_copy(void __iomem *iobase, u32 lim)
  42 {
  43         struct nvram_header __iomem *header;
  44         int i;
  45         u32 off;
  46         u32 *src, *dst;
  47         u32 size;
  48
  49         if (nvram_buf[0]) {
  50                 pr_warn("nvram already initialized\n");
  51                 return -EEXIST;
  52         }
  53
  54         /* TODO: when nvram is on nand flash check for bad blocks first. */
  55         off = FLASH_MIN;
  56         while (off <= lim) {
  57                 /* Windowed flash access */
  58                 size = find_nvram_size(iobase + off);
  59                 if (size) {
  60                         header = (struct nvram_header *)(iobase + off - size);
  61                         goto found;
  62                 }
  63                 off <<= 1;
  64         }
  65
  66         /* Try embedded NVRAM at 4 KB and 1 KB as last resorts */
  67         header = (struct nvram_header *)(iobase + 4096);
  68         if (header->magic == NVRAM_HEADER) {
  69                 size = NVRAM_SPACE;
  70                 goto found;
  71         }
  72
  73         header = (struct nvram_header *)(iobase + 1024);
  74         if (header->magic == NVRAM_HEADER) {
  75                 size = NVRAM_SPACE;
  76                 goto found;
  77         }
  78
  79         pr_err("no nvram found\n");
  80         return -ENXIO;
  81
  82 found:
  83
  84         if (header->len > size)
  85                 pr_err("The nvram size accoridng to the header seems to be bigger than the partition on flash\n");
  86         if (header->len > NVRAM_SPACE)
  87                 pr_err("nvram on flash (%i bytes) is bigger than the reserved space in memory, will just copy the first %i bytes\n",
  88                        header->len, NVRAM_SPACE);
  89
  90         src = (u32 *) header;
  91         dst = (u32 *) nvram_buf;
  92         for (i = 0; i < sizeof(struct nvram_header); i += 4)
  93                 *dst++ = *src++;
  94         for (; i < header->len && i < NVRAM_SPACE && i < size; i += 4)
  95                 *dst++ = le32_to_cpu(*src++);
  96         memset(dst, 0x0, NVRAM_SPACE - i);
  97
  98         return 0;
  99 }
 100
 101 /*
 102  * On bcm47xx we need access to the NVRAM very early, so we can't use mtd
 103  * subsystem to access flash. We can't even use platform device / driver to
 104  * store memory offset.
 105  * To handle this we provide following symbol. It's supposed to be called as
 106  * soon as we get info about flash device, before any NVRAM entry is needed.
 107  */
 108 int bcm47xx_nvram_init_from_mem(u32 base, u32 lim)
 109 {
 110         void __iomem *iobase;
 111         int err;
 112
 113         iobase = ioremap_nocache(base, lim);
 114         if (!iobase)
 115                 return -ENOMEM;
 116
 117         err = nvram_find_and_copy(iobase, lim);
 118
 119         iounmap(iobase);
 120
 121         return err;
 122 }
 123
 124 static int nvram_init(void)
 125 {
 126         /* TODO: Look for MTD "nvram" partition */
 127
 128         return -ENXIO;
 129 }
 130
 131 int bcm47xx_nvram_getenv(char *name, char *val, size_t val_len)
 132 {
 133         char *var, *value, *end, *eq;
 134         int err;
 135
 136         if (!name)
 137                 return -EINVAL;
 138
 139         if (!nvram_buf[0]) {
 140                 err = nvram_init();
 141                 if (err)
 142                         return err;
 143         }
 144
 145         /* Look for name=value and return value */
 146         var = &nvram_buf[sizeof(struct nvram_header)];
 147         end = nvram_buf + sizeof(nvram_buf) - 2;
 148         end[0] = end[1] = '\0';
 149         for (; *var; var = value + strlen(value) + 1) {
 150                 eq = strchr(var, '=');
 151                 if (!eq)
 152                         break;
 153                 value = eq + 1;
 154                 if ((eq - var) == strlen(name) &&
 155                         strncmp(var, name, (eq - var)) == 0) {
 156                         return snprintf(val, val_len, "%s", value);
 157                 }
 158         }
 159         return -ENOENT;
 160 }
 161 EXPORT_SYMBOL(bcm47xx_nvram_getenv);
 162
 163 int bcm47xx_nvram_gpio_pin(const char *name)
 164 {
 165         int i, err;
 166         char nvram_var[10];
 167         char buf[30];
 168
 169         for (i = 0; i < 32; i++) {
 170                 err = snprintf(nvram_var, sizeof(nvram_var), "gpio%i", i);
 171                 if (err <= 0)
 172                         continue;
 173                 err = bcm47xx_nvram_getenv(nvram_var, buf, sizeof(buf));
 174                 if (err <= 0)
 175                         continue;
 176                 if (!strcmp(name, buf))
 177                         return i;
 178         }
 179         return -ENOENT;
 180 }
 181 EXPORT_SYMBOL(bcm47xx_nvram_gpio_pin);