summaryrefslogtreecommitdiff
path: root/target/linux/brcm47xx/files/arch/mips/bcm947xx/cfe_env.c
blob: c1d5eeef59fc2c78e5bb8ef93bf3e7c5124a25df (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
/*
 * 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;

}