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/*
* CFE environment variable access
*
* Copyright 2001-2003, Broadcom Corporation
* Copyright 2006, Felix Fietkau <nbd@openwrt.org>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#define NVRAM_SIZE (0x1ff0)
static char _nvdata[NVRAM_SIZE];
static char _valuestr[256];
/*
* TLV types. These codes are used in the "type-length-value"
* encoding of the items stored in the NVRAM device (flash or EEPROM)
*
* The layout of the flash/nvram is as follows:
*
* <type> <length> <data ...> <type> <length> <data ...> <type_end>
*
* The type code of "ENV_TLV_TYPE_END" marks the end of the list.
* The "length" field marks the length of the data section, not
* including the type and length fields.
*
* Environment variables are stored as follows:
*
* <type_env> <length> <flags> <name> = <value>
*
* If bit 0 (low bit) is set, the length is an 8-bit value.
* If bit 0 (low bit) is clear, the length is a 16-bit value
*
* Bit 7 set indicates "user" TLVs. In this case, bit 0 still
* indicates the size of the length field.
*
* Flags are from the constants below:
*
*/
#define ENV_LENGTH_16BITS 0x00 /* for low bit */
#define ENV_LENGTH_8BITS 0x01
#define ENV_TYPE_USER 0x80
#define ENV_CODE_SYS(n,l) (((n)<<1)|(l))
#define ENV_CODE_USER(n,l) ((((n)<<1)|(l)) | ENV_TYPE_USER)
/*
* The actual TLV types we support
*/
#define ENV_TLV_TYPE_END 0x00
#define ENV_TLV_TYPE_ENV ENV_CODE_SYS(0,ENV_LENGTH_8BITS)
/*
* Environment variable flags
*/
#define ENV_FLG_NORMAL 0x00 /* normal read/write */
#define ENV_FLG_BUILTIN 0x01 /* builtin - not stored in flash */
#define ENV_FLG_READONLY 0x02 /* read-only - cannot be changed */
#define ENV_FLG_MASK 0xFF /* mask of attributes we keep */
#define ENV_FLG_ADMIN 0x100 /* lets us internally override permissions */
/* *********************************************************************
* _nvram_read(buffer,offset,length)
*
* Read data from the NVRAM device
*
* Input parameters:
* buffer - destination buffer
* offset - offset of data to read
* length - number of bytes to read
*
* Return value:
* number of bytes read, or <0 if error occured
********************************************************************* */
static int
_nvram_read(unsigned char *nv_buf, unsigned char *buffer, int offset, int length)
{
int i;
if (offset > NVRAM_SIZE)
return -1;
for ( i = 0; i < length; i++) {
buffer[i] = ((volatile unsigned char*)nv_buf)[offset + i];
}
return length;
}
static char*
_strnchr(const char *dest,int c,size_t cnt)
{
while (*dest && (cnt > 0)) {
if (*dest == c) return (char *) dest;
dest++;
cnt--;
}
return NULL;
}
/*
* Core support API: Externally visible.
*/
/*
* Get the value of an NVRAM variable
* @param name name of variable to get
* @return value of variable or NULL if undefined
*/
char*
cfe_env_get(unsigned char *nv_buf, char* name)
{
int size;
unsigned char *buffer;
unsigned char *ptr;
unsigned char *envval;
unsigned int reclen;
unsigned int rectype;
int offset;
int flg;
if (!strcmp(name, "nvram_type"))
return "cfe";
size = NVRAM_SIZE;
buffer = &_nvdata[0];
ptr = buffer;
offset = 0;
/* Read the record type and length */
if (_nvram_read(nv_buf, ptr,offset,1) != 1) {
goto error;
}
while ((*ptr != ENV_TLV_TYPE_END) && (size > 1)) {
/* Adjust pointer for TLV type */
rectype = *(ptr);
offset++;
size--;
/*
* Read the length. It can be either 1 or 2 bytes
* depending on the code
*/
if (rectype & ENV_LENGTH_8BITS) {
/* Read the record type and length - 8 bits */
if (_nvram_read(nv_buf, ptr,offset,1) != 1) {
goto error;
}
reclen = *(ptr);
size--;
offset++;
}
else {
/* Read the record type and length - 16 bits, MSB first */
if (_nvram_read(nv_buf, ptr,offset,2) != 2) {
goto error;
}
reclen = (((unsigned int) *(ptr)) << 8) + (unsigned int) *(ptr+1);
size -= 2;
offset += 2;
}
if (reclen > size)
break; /* should not happen, bad NVRAM */
switch (rectype) {
case ENV_TLV_TYPE_ENV:
/* Read the TLV data */
if (_nvram_read(nv_buf, ptr,offset,reclen) != reclen)
goto error;
flg = *ptr++;
envval = (unsigned char *) _strnchr(ptr,'=',(reclen-1));
if (envval) {
*envval++ = '\0';
memcpy(_valuestr,envval,(reclen-1)-(envval-ptr));
_valuestr[(reclen-1)-(envval-ptr)] = '\0';
#if 0
printk(KERN_INFO "NVRAM:%s=%s\n", ptr, _valuestr);
#endif
if(!strcmp(ptr, name)){
return _valuestr;
}
if((strlen(ptr) > 1) && !strcmp(&ptr[1], name))
return _valuestr;
}
break;
default:
/* Unknown TLV type, skip it. */
break;
}
/*
* Advance to next TLV
*/
size -= (int)reclen;
offset += reclen;
/* Read the next record type */
ptr = buffer;
if (_nvram_read(nv_buf, ptr,offset,1) != 1)
goto error;
}
error:
return NULL;
}
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