| 1 | /* |
| 2 | * CFE environment variable access |
| 3 | * |
| 4 | * Copyright 2001-2003, Broadcom Corporation |
| 5 | * Copyright 2006, Felix Fietkau <nbd@openwrt.org> |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or modify it |
| 8 | * under the terms of the GNU General Public License as published by the |
| 9 | * Free Software Foundation; either version 2 of the License, or (at your |
| 10 | * option) any later version. |
| 11 | */ |
| 12 | |
| 13 | #include <linux/init.h> |
| 14 | #include <linux/module.h> |
| 15 | #include <linux/kernel.h> |
| 16 | #include <linux/string.h> |
| 17 | #include <asm/io.h> |
| 18 | #include <asm/uaccess.h> |
| 19 | |
| 20 | #define NVRAM_SIZE (0x1ff0) |
| 21 | static char _nvdata[NVRAM_SIZE]; |
| 22 | static char _valuestr[256]; |
| 23 | |
| 24 | /* |
| 25 | * TLV types. These codes are used in the "type-length-value" |
| 26 | * encoding of the items stored in the NVRAM device (flash or EEPROM) |
| 27 | * |
| 28 | * The layout of the flash/nvram is as follows: |
| 29 | * |
| 30 | * <type> <length> <data ...> <type> <length> <data ...> <type_end> |
| 31 | * |
| 32 | * The type code of "ENV_TLV_TYPE_END" marks the end of the list. |
| 33 | * The "length" field marks the length of the data section, not |
| 34 | * including the type and length fields. |
| 35 | * |
| 36 | * Environment variables are stored as follows: |
| 37 | * |
| 38 | * <type_env> <length> <flags> <name> = <value> |
| 39 | * |
| 40 | * If bit 0 (low bit) is set, the length is an 8-bit value. |
| 41 | * If bit 0 (low bit) is clear, the length is a 16-bit value |
| 42 | * |
| 43 | * Bit 7 set indicates "user" TLVs. In this case, bit 0 still |
| 44 | * indicates the size of the length field. |
| 45 | * |
| 46 | * Flags are from the constants below: |
| 47 | * |
| 48 | */ |
| 49 | #define ENV_LENGTH_16BITS 0x00 /* for low bit */ |
| 50 | #define ENV_LENGTH_8BITS 0x01 |
| 51 | |
| 52 | #define ENV_TYPE_USER 0x80 |
| 53 | |
| 54 | #define ENV_CODE_SYS(n,l) (((n)<<1)|(l)) |
| 55 | #define ENV_CODE_USER(n,l) ((((n)<<1)|(l)) | ENV_TYPE_USER) |
| 56 | |
| 57 | /* |
| 58 | * The actual TLV types we support |
| 59 | */ |
| 60 | |
| 61 | #define ENV_TLV_TYPE_END 0x00 |
| 62 | #define ENV_TLV_TYPE_ENV ENV_CODE_SYS(0,ENV_LENGTH_8BITS) |
| 63 | |
| 64 | /* |
| 65 | * Environment variable flags |
| 66 | */ |
| 67 | |
| 68 | #define ENV_FLG_NORMAL 0x00 /* normal read/write */ |
| 69 | #define ENV_FLG_BUILTIN 0x01 /* builtin - not stored in flash */ |
| 70 | #define ENV_FLG_READONLY 0x02 /* read-only - cannot be changed */ |
| 71 | |
| 72 | #define ENV_FLG_MASK 0xFF /* mask of attributes we keep */ |
| 73 | #define ENV_FLG_ADMIN 0x100 /* lets us internally override permissions */ |
| 74 | |
| 75 | |
| 76 | /* ********************************************************************* |
| 77 | * _nvram_read(buffer,offset,length) |
| 78 | * |
| 79 | * Read data from the NVRAM device |
| 80 | * |
| 81 | * Input parameters: |
| 82 | * buffer - destination buffer |
| 83 | * offset - offset of data to read |
| 84 | * length - number of bytes to read |
| 85 | * |
| 86 | * Return value: |
| 87 | * number of bytes read, or <0 if error occured |
| 88 | ********************************************************************* */ |
| 89 | static int |
| 90 | _nvram_read(unsigned char *nv_buf, unsigned char *buffer, int offset, int length) |
| 91 | { |
| 92 | int i; |
| 93 | if (offset > NVRAM_SIZE) |
| 94 | return -1; |
| 95 | |
| 96 | for ( i = 0; i < length; i++) { |
| 97 | buffer[i] = ((volatile unsigned char*)nv_buf)[offset + i]; |
| 98 | } |
| 99 | return length; |
| 100 | } |
| 101 | |
| 102 | |
| 103 | static char* |
| 104 | _strnchr(const char *dest,int c,size_t cnt) |
| 105 | { |
| 106 | while (*dest && (cnt > 0)) { |
| 107 | if (*dest == c) return (char *) dest; |
| 108 | dest++; |
| 109 | cnt--; |
| 110 | } |
| 111 | return NULL; |
| 112 | } |
| 113 | |
| 114 | |
| 115 | |
| 116 | /* |
| 117 | * Core support API: Externally visible. |
| 118 | */ |
| 119 | |
| 120 | /* |
| 121 | * Get the value of an NVRAM variable |
| 122 | * @param name name of variable to get |
| 123 | * @return value of variable or NULL if undefined |
| 124 | */ |
| 125 | |
| 126 | char* |
| 127 | cfe_env_get(unsigned char *nv_buf, char* name) |
| 128 | { |
| 129 | int size; |
| 130 | unsigned char *buffer; |
| 131 | unsigned char *ptr; |
| 132 | unsigned char *envval; |
| 133 | unsigned int reclen; |
| 134 | unsigned int rectype; |
| 135 | int offset; |
| 136 | int flg; |
| 137 | |
| 138 | if (!strcmp(name, "nvram_type")) |
| 139 | return "cfe"; |
| 140 | |
| 141 | size = NVRAM_SIZE; |
| 142 | buffer = &_nvdata[0]; |
| 143 | |
| 144 | ptr = buffer; |
| 145 | offset = 0; |
| 146 | |
| 147 | /* Read the record type and length */ |
| 148 | if (_nvram_read(nv_buf, ptr,offset,1) != 1) { |
| 149 | goto error; |
| 150 | } |
| 151 | |
| 152 | while ((*ptr != ENV_TLV_TYPE_END) && (size > 1)) { |
| 153 | |
| 154 | /* Adjust pointer for TLV type */ |
| 155 | rectype = *(ptr); |
| 156 | offset++; |
| 157 | size--; |
| 158 | |
| 159 | /* |
| 160 | * Read the length. It can be either 1 or 2 bytes |
| 161 | * depending on the code |
| 162 | */ |
| 163 | if (rectype & ENV_LENGTH_8BITS) { |
| 164 | /* Read the record type and length - 8 bits */ |
| 165 | if (_nvram_read(nv_buf, ptr,offset,1) != 1) { |
| 166 | goto error; |
| 167 | } |
| 168 | reclen = *(ptr); |
| 169 | size--; |
| 170 | offset++; |
| 171 | } |
| 172 | else { |
| 173 | /* Read the record type and length - 16 bits, MSB first */ |
| 174 | if (_nvram_read(nv_buf, ptr,offset,2) != 2) { |
| 175 | goto error; |
| 176 | } |
| 177 | reclen = (((unsigned int) *(ptr)) << 8) + (unsigned int) *(ptr+1); |
| 178 | size -= 2; |
| 179 | offset += 2; |
| 180 | } |
| 181 | |
| 182 | if (reclen > size) |
| 183 | break; /* should not happen, bad NVRAM */ |
| 184 | |
| 185 | switch (rectype) { |
| 186 | case ENV_TLV_TYPE_ENV: |
| 187 | /* Read the TLV data */ |
| 188 | if (_nvram_read(nv_buf, ptr,offset,reclen) != reclen) |
| 189 | goto error; |
| 190 | flg = *ptr++; |
| 191 | envval = (unsigned char *) _strnchr(ptr,'=',(reclen-1)); |
| 192 | if (envval) { |
| 193 | *envval++ = '\0'; |
| 194 | memcpy(_valuestr,envval,(reclen-1)-(envval-ptr)); |
| 195 | _valuestr[(reclen-1)-(envval-ptr)] = '\0'; |
| 196 | #if 0 |
| 197 | printk(KERN_INFO "NVRAM:%s=%s\n", ptr, _valuestr); |
| 198 | #endif |
| 199 | if(!strcmp(ptr, name)){ |
| 200 | return _valuestr; |
| 201 | } |
| 202 | if((strlen(ptr) > 1) && !strcmp(&ptr[1], name)) |
| 203 | return _valuestr; |
| 204 | } |
| 205 | break; |
| 206 | |
| 207 | default: |
| 208 | /* Unknown TLV type, skip it. */ |
| 209 | break; |
| 210 | } |
| 211 | |
| 212 | /* |
| 213 | * Advance to next TLV |
| 214 | */ |
| 215 | |
| 216 | size -= (int)reclen; |
| 217 | offset += reclen; |
| 218 | |
| 219 | /* Read the next record type */ |
| 220 | ptr = buffer; |
| 221 | if (_nvram_read(nv_buf, ptr,offset,1) != 1) |
| 222 | goto error; |
| 223 | } |
| 224 | |
| 225 | error: |
| 226 | return NULL; |
| 227 | |
| 228 | } |
| 229 | |
| 230 | |
