target/linux/brcm47xx-2.6/files/arch/mips/bcm947xx/cfe_env.c

   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] __initdata;
  22 static char _valuestr[256] __initdata;
  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