target/linux/brcm-2.4/files/arch/mips/bcm947xx/cfe_env.c

   1 /*
   2  * NVRAM variable manipulation (Linux kernel half)
   3  *
   4  * Copyright 2001-2003, Broadcom Corporation
   5  * All Rights Reserved.
   6  *
   7  * THIS SOFTWARE IS OFFERED "AS IS", AND BROADCOM GRANTS NO WARRANTIES OF ANY
   8  * KIND, EXPRESS OR IMPLIED, BY STATUTE, COMMUNICATION OR OTHERWISE. BROADCOM
   9  * SPECIFICALLY DISCLAIMS ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS
  10  * FOR A SPECIFIC PURPOSE OR NONINFRINGEMENT CONCERNING THIS SOFTWARE.
  11  *
  12  */
  13
  14 #include <linux/config.h>
  15 #include <linux/init.h>
  16 #include <linux/module.h>
  17 #include <linux/kernel.h>
  18 #include <linux/string.h>
  19 #include <asm/io.h>
  20 #include <asm/uaccess.h>
  21
  22 #include <typedefs.h>
  23 #include <osl.h>
  24 #include <bcmendian.h>
  25
  26 #define NVRAM_SIZE       (0x1ff0)
  27 static char _nvdata[NVRAM_SIZE] __initdata;
  28 static char _valuestr[256] __initdata;
  29
  30 /*
  31  * TLV types.  These codes are used in the "type-length-value"
  32  * encoding of the items stored in the NVRAM device (flash or EEPROM)
  33  *
  34  * The layout of the flash/nvram is as follows:
  35  *
  36  * <type> <length> <data ...> <type> <length> <data ...> <type_end>
  37  *
  38  * The type code of "ENV_TLV_TYPE_END" marks the end of the list.
  39  * The "length" field marks the length of the data section, not
  40  * including the type and length fields.
  41  *
  42  * Environment variables are stored as follows:
  43  *
  44  * <type_env> <length> <flags> <name> = <value>
  45  *
  46  * If bit 0 (low bit) is set, the length is an 8-bit value.
  47  * If bit 0 (low bit) is clear, the length is a 16-bit value
  48  *
  49  * Bit 7 set indicates "user" TLVs.  In this case, bit 0 still
  50  * indicates the size of the length field.
  51  *
  52  * Flags are from the constants below:
  53  *
  54  */
  55 #define ENV_LENGTH_16BITS       0x00    /* for low bit */
  56 #define ENV_LENGTH_8BITS        0x01
  57
  58 #define ENV_TYPE_USER           0x80
  59
  60 #define ENV_CODE_SYS(n,l) (((n)<<1)|(l))
  61 #define ENV_CODE_USER(n,l) ((((n)<<1)|(l)) | ENV_TYPE_USER)
  62
  63 /*
  64  * The actual TLV types we support
  65  */
  66
  67 #define ENV_TLV_TYPE_END        0x00
  68 #define ENV_TLV_TYPE_ENV        ENV_CODE_SYS(0,ENV_LENGTH_8BITS)
  69
  70 /*
  71  * Environment variable flags
  72  */
  73
  74 #define ENV_FLG_NORMAL          0x00    /* normal read/write */
  75 #define ENV_FLG_BUILTIN         0x01    /* builtin - not stored in flash */
  76 #define ENV_FLG_READONLY        0x02    /* read-only - cannot be changed */
  77
  78 #define ENV_FLG_MASK            0xFF    /* mask of attributes we keep */
  79 #define ENV_FLG_ADMIN           0x100   /* lets us internally override permissions */
  80
  81
  82 /*  *********************************************************************
  83     *  _nvram_read(buffer,offset,length)
  84     *
  85     *  Read data from the NVRAM device
  86     *
  87     *  Input parameters:
  88     *      buffer - destination buffer
  89     *      offset - offset of data to read
  90     *      length - number of bytes to read
  91     *
  92     *  Return value:
  93     *      number of bytes read, or <0 if error occured
  94     ********************************************************************* */
  95 static int
  96 _nvram_read(unsigned char *nv_buf, unsigned char *buffer, int offset, int length)
  97 {
  98     int i;
  99     if (offset > NVRAM_SIZE)
 100         return -1;
 101
 102     for ( i = 0; i < length; i++) {
 103         buffer[i] = ((volatile unsigned char*)nv_buf)[offset + i];
 104     }
 105     return length;
 106 }
 107
 108
 109 static char*
 110 _strnchr(const char *dest,int c,size_t cnt)
 111 {
 112         while (*dest && (cnt > 0)) {
 113         if (*dest == c) return (char *) dest;
 114         dest++;
 115         cnt--;
 116         }
 117         return NULL;
 118 }
 119
 120
 121
 122 /*
 123  * Core support API: Externally visible.
 124  */
 125
 126 /*
 127  * Get the value of an NVRAM variable
 128  * @param       name    name of variable to get
 129  * @return      value of variable or NULL if undefined
 130  */
 131
 132 char*
 133 cfe_env_get(unsigned char *nv_buf, char* name)
 134 {
 135     int size;
 136     unsigned char *buffer;
 137     unsigned char *ptr;
 138     unsigned char *envval;
 139     unsigned int reclen;
 140     unsigned int rectype;
 141     int offset;
 142     int flg;
 143
 144     size = NVRAM_SIZE;
 145     buffer = &_nvdata[0];
 146
 147     ptr = buffer;
 148     offset = 0;
 149
 150     /* Read the record type and length */
 151     if (_nvram_read(nv_buf, ptr,offset,1) != 1) {
 152         goto error;
 153     }
 154
 155     while ((*ptr != ENV_TLV_TYPE_END)  && (size > 1)) {
 156
 157         /* Adjust pointer for TLV type */
 158         rectype = *(ptr);
 159         offset++;
 160         size--;
 161
 162         /*
 163          * Read the length.  It can be either 1 or 2 bytes
 164          * depending on the code
 165          */
 166         if (rectype & ENV_LENGTH_8BITS) {
 167             /* Read the record type and length - 8 bits */
 168             if (_nvram_read(nv_buf, ptr,offset,1) != 1) {
 169                 goto error;
 170             }
 171             reclen = *(ptr);
 172             size--;
 173             offset++;
 174         }
 175         else {
 176             /* Read the record type and length - 16 bits, MSB first */
 177             if (_nvram_read(nv_buf, ptr,offset,2) != 2) {
 178                 goto error;
 179             }
 180             reclen = (((unsigned int) *(ptr)) << 8) + (unsigned int) *(ptr+1);
 181             size -= 2;
 182             offset += 2;
 183         }
 184
 185         if (reclen > size)
 186             break;      /* should not happen, bad NVRAM */
 187
 188         switch (rectype) {
 189             case ENV_TLV_TYPE_ENV:
 190                 /* Read the TLV data */
 191                 if (_nvram_read(nv_buf, ptr,offset,reclen) != reclen)
 192                     goto error;
 193                 flg = *ptr++;
 194                 envval = (unsigned char *) _strnchr(ptr,'=',(reclen-1));
 195                 if (envval) {
 196                     *envval++ = '\0';
 197                     memcpy(_valuestr,envval,(reclen-1)-(envval-ptr));
 198                     _valuestr[(reclen-1)-(envval-ptr)] = '\0';
 199 #if 0
 200                     printk(KERN_INFO "NVRAM:%s=%s\n", ptr, _valuestr);
 201 #endif
 202                     if(!strcmp(ptr, name)){
 203                         return _valuestr;
 204                     }
 205                     if((strlen(ptr) > 1) && !strcmp(&ptr[1], name))
 206                         return _valuestr;
 207                 }
 208                 break;
 209
 210             default:
 211                 /* Unknown TLV type, skip it. */
 212                 break;
 213             }
 214
 215         /*
 216          * Advance to next TLV
 217          */
 218
 219         size -= (int)reclen;
 220         offset += reclen;
 221
 222         /* Read the next record type */
 223         ptr = buffer;
 224         if (_nvram_read(nv_buf, ptr,offset,1) != 1)
 225             goto error;
 226         }
 227
 228 error:
 229     return NULL;
 230
 231 }
 232