aboutsummaryrefslogtreecommitdiff
path: root/common/fdt_wrappers.c
blob: e67fdb00548074f1cd04255e0e17aff355f9c31d (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
/*
 * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

/* Helper functions to offer easier navigation of Device Tree Blob */

#include <assert.h>
#include <string.h>

#include <libfdt.h>

#include <common/debug.h>
#include <common/fdt_wrappers.h>

/*
 * Read cells from a given property of the given node. At most 2 cells of the
 * property are read, and pointer is updated. Returns 0 on success, and -1 upon
 * error
 */
int fdtw_read_cells(const void *dtb, int node, const char *prop,
		unsigned int cells, void *value)
{
	const uint32_t *value_ptr;
	uint32_t hi = 0, lo;
	int value_len;

	assert(dtb != NULL);
	assert(prop != NULL);
	assert(value != NULL);
	assert(node >= 0);

	/* We expect either 1 or 2 cell property */
	assert(cells <= 2U);

	/* Access property and obtain its length (in bytes) */
	value_ptr = fdt_getprop_namelen(dtb, node, prop, (int)strlen(prop),
			&value_len);
	if (value_ptr == NULL) {
		WARN("Couldn't find property %s in dtb\n", prop);
		return -1;
	}

	/* Verify that property length accords with cell length */
	if (NCELLS((unsigned int)value_len) != cells) {
		WARN("Property length mismatch\n");
		return -1;
	}

	if (cells == 2U) {
		hi = fdt32_to_cpu(*value_ptr);
		value_ptr++;
	}

	lo = fdt32_to_cpu(*value_ptr);

	if (cells == 2U)
		*((uint64_t *) value) = ((uint64_t) hi << 32) | lo;
	else
		*((uint32_t *) value) = lo;

	return 0;
}

/*
 * Read cells from a given property of the given node. Any number of 32-bit
 * cells of the property can be read. The fdt pointer is updated. Returns 0 on
 * success, and -1 on error.
 */
int fdtw_read_array(const void *dtb, int node, const char *prop,
		unsigned int cells, void *value)
{
	const uint32_t *value_ptr;
	int value_len;

	assert(dtb != NULL);
	assert(prop != NULL);
	assert(value != NULL);
	assert(node >= 0);

	/* Access property and obtain its length (in bytes) */
	value_ptr = fdt_getprop_namelen(dtb, node, prop, (int)strlen(prop),
			&value_len);
	if (value_ptr == NULL) {
		WARN("Couldn't find property %s in dtb\n", prop);
		return -1;
	}

	/* Verify that property length accords with cell length */
	if (NCELLS((unsigned int)value_len) != cells) {
		WARN("Property length mismatch\n");
		return -1;
	}

	uint32_t *dst = value;

	for (unsigned int i = 0U; i < cells; i++) {
		dst[i] = fdt32_to_cpu(value_ptr[i]);
	}

	return 0;
}

/*
 * Read string from a given property of the given node. Up to 'size - 1'
 * characters are read, and a NUL terminator is added. Returns 0 on success,
 * and -1 upon error.
 */
int fdtw_read_string(const void *dtb, int node, const char *prop,
		char *str, size_t size)
{
	const char *ptr;
	size_t len;

	assert(dtb != NULL);
	assert(node >= 0);
	assert(prop != NULL);
	assert(str != NULL);
	assert(size > 0U);

	ptr = fdt_getprop_namelen(dtb, node, prop, (int)strlen(prop), NULL);
	if (ptr == NULL) {
		WARN("Couldn't find property %s in dtb\n", prop);
		return -1;
	}

	len = strlcpy(str, ptr, size);
	if (len >= size) {
		WARN("String of property %s in dtb has been truncated\n", prop);
		return -1;
	}

	return 0;
}

/*
 * Write cells in place to a given property of the given node. At most 2 cells
 * of the property are written. Returns 0 on success, and -1 upon error.
 */
int fdtw_write_inplace_cells(void *dtb, int node, const char *prop,
		unsigned int cells, void *value)
{
	int err, len;

	assert(dtb != NULL);
	assert(prop != NULL);
	assert(value != NULL);
	assert(node >= 0);

	/* We expect either 1 or 2 cell property */
	assert(cells <= 2U);

	if (cells == 2U)
		*(uint64_t *)value = cpu_to_fdt64(*(uint64_t *)value);
	else
		*(uint32_t *)value = cpu_to_fdt32(*(uint32_t *)value);

	len = (int)cells * 4;

	/* Set property value in place */
	err = fdt_setprop_inplace(dtb, node, prop, value, len);
	if (err != 0) {
		WARN("Modify property %s failed with error %d\n", prop, err);
		return -1;
	}

	return 0;
}