1 /* 2 * Copyright (c) 2018-2020, ARM Limited and Contributors. All rights reserved. 3 * 4 * SPDX-License-Identifier: BSD-3-Clause 5 */ 6 7 /* Helper functions to offer easier navigation of Device Tree Blob */ 8 9 #include <assert.h> 10 #include <string.h> 11 12 #include <libfdt.h> 13 14 #include <common/debug.h> 15 #include <common/fdt_wrappers.h> 16 17 /* 18 * Read cells from a given property of the given node. At most 2 cells of the 19 * property are read, and pointer is updated. Returns 0 on success, and -1 upon 20 * error 21 */ 22 int fdtw_read_cells(const void *dtb, int node, const char *prop, 23 unsigned int cells, void *value) 24 { 25 const uint32_t *value_ptr; 26 uint32_t hi = 0, lo; 27 int value_len; 28 29 assert(dtb != NULL); 30 assert(prop != NULL); 31 assert(value != NULL); 32 assert(node >= 0); 33 34 /* We expect either 1 or 2 cell property */ 35 assert(cells <= 2U); 36 37 /* Access property and obtain its length (in bytes) */ 38 value_ptr = fdt_getprop_namelen(dtb, node, prop, (int)strlen(prop), 39 &value_len); 40 if (value_ptr == NULL) { 41 WARN("Couldn't find property %s in dtb\n", prop); 42 return -1; 43 } 44 45 /* Verify that property length accords with cell length */ 46 if (NCELLS((unsigned int)value_len) != cells) { 47 WARN("Property length mismatch\n"); 48 return -1; 49 } 50 51 if (cells == 2U) { 52 hi = fdt32_to_cpu(*value_ptr); 53 value_ptr++; 54 } 55 56 lo = fdt32_to_cpu(*value_ptr); 57 58 if (cells == 2U) 59 *((uint64_t *) value) = ((uint64_t) hi << 32) | lo; 60 else 61 *((uint32_t *) value) = lo; 62 63 return 0; 64 } 65 66 /* 67 * Read cells from a given property of the given node. Any number of 32-bit 68 * cells of the property can be read. Returns 0 on success, or a negative 69 * FDT error value otherwise. 70 */ 71 int fdt_read_uint32_array(const void *dtb, int node, const char *prop_name, 72 unsigned int cells, uint32_t *value) 73 { 74 const fdt32_t *prop; 75 int value_len; 76 77 assert(dtb != NULL); 78 assert(prop_name != NULL); 79 assert(value != NULL); 80 assert(node >= 0); 81 82 /* Access property and obtain its length (in bytes) */ 83 prop = fdt_getprop(dtb, node, prop_name, &value_len); 84 if (prop == NULL) { 85 WARN("Couldn't find property %s in dtb\n", prop_name); 86 return -FDT_ERR_NOTFOUND; 87 } 88 89 /* Verify that property length can fill the entire array. */ 90 if (NCELLS((unsigned int)value_len) < cells) { 91 WARN("Property length mismatch\n"); 92 return -FDT_ERR_BADVALUE; 93 } 94 95 for (unsigned int i = 0U; i < cells; i++) { 96 value[i] = fdt32_to_cpu(prop[i]); 97 } 98 99 return 0; 100 } 101 102 /* 103 * Read bytes from a given property of the given node. Any number of 104 * bytes of the property can be read. The fdt pointer is updated. 105 * Returns 0 on success, and -1 on error. 106 */ 107 int fdtw_read_bytes(const void *dtb, int node, const char *prop, 108 unsigned int length, void *value) 109 { 110 const void *ptr; 111 int value_len; 112 113 assert(dtb != NULL); 114 assert(prop != NULL); 115 assert(value != NULL); 116 assert(node >= 0); 117 118 /* Access property and obtain its length (in bytes) */ 119 ptr = fdt_getprop_namelen(dtb, node, prop, (int)strlen(prop), 120 &value_len); 121 if (ptr == NULL) { 122 WARN("Couldn't find property %s in dtb\n", prop); 123 return -1; 124 } 125 126 /* Verify that property length is not less than number of bytes */ 127 if ((unsigned int)value_len < length) { 128 WARN("Property length mismatch\n"); 129 return -1; 130 } 131 132 (void)memcpy(value, ptr, length); 133 134 return 0; 135 } 136 137 /* 138 * Read string from a given property of the given node. Up to 'size - 1' 139 * characters are read, and a NUL terminator is added. Returns 0 on success, 140 * and -1 upon error. 141 */ 142 int fdtw_read_string(const void *dtb, int node, const char *prop, 143 char *str, size_t size) 144 { 145 const char *ptr; 146 size_t len; 147 148 assert(dtb != NULL); 149 assert(node >= 0); 150 assert(prop != NULL); 151 assert(str != NULL); 152 assert(size > 0U); 153 154 ptr = fdt_getprop_namelen(dtb, node, prop, (int)strlen(prop), NULL); 155 if (ptr == NULL) { 156 WARN("Couldn't find property %s in dtb\n", prop); 157 return -1; 158 } 159 160 len = strlcpy(str, ptr, size); 161 if (len >= size) { 162 WARN("String of property %s in dtb has been truncated\n", prop); 163 return -1; 164 } 165 166 return 0; 167 } 168 169 /* 170 * Write cells in place to a given property of the given node. At most 2 cells 171 * of the property are written. Returns 0 on success, and -1 upon error. 172 */ 173 int fdtw_write_inplace_cells(void *dtb, int node, const char *prop, 174 unsigned int cells, void *value) 175 { 176 int err, len; 177 178 assert(dtb != NULL); 179 assert(prop != NULL); 180 assert(value != NULL); 181 assert(node >= 0); 182 183 /* We expect either 1 or 2 cell property */ 184 assert(cells <= 2U); 185 186 if (cells == 2U) 187 *(uint64_t *)value = cpu_to_fdt64(*(uint64_t *)value); 188 else 189 *(uint32_t *)value = cpu_to_fdt32(*(uint32_t *)value); 190 191 len = (int)cells * 4; 192 193 /* Set property value in place */ 194 err = fdt_setprop_inplace(dtb, node, prop, value, len); 195 if (err != 0) { 196 WARN("Modify property %s failed with error %d\n", prop, err); 197 return -1; 198 } 199 200 return 0; 201 } 202 203 /* 204 * Write bytes in place to a given property of the given node. 205 * Any number of bytes of the property can be written. 206 * Returns 0 on success, and < 0 on error. 207 */ 208 int fdtw_write_inplace_bytes(void *dtb, int node, const char *prop, 209 unsigned int length, const void *data) 210 { 211 const void *ptr; 212 int namelen, value_len, err; 213 214 assert(dtb != NULL); 215 assert(prop != NULL); 216 assert(data != NULL); 217 assert(node >= 0); 218 219 namelen = (int)strlen(prop); 220 221 /* Access property and obtain its length in bytes */ 222 ptr = fdt_getprop_namelen(dtb, node, prop, namelen, &value_len); 223 if (ptr == NULL) { 224 WARN("Couldn't find property %s in dtb\n", prop); 225 return -1; 226 } 227 228 /* Verify that property length is not less than number of bytes */ 229 if ((unsigned int)value_len < length) { 230 WARN("Property length mismatch\n"); 231 return -1; 232 } 233 234 /* Set property value in place */ 235 err = fdt_setprop_inplace_namelen_partial(dtb, node, prop, 236 namelen, 0, 237 data, (int)length); 238 if (err != 0) { 239 WARN("Set property %s failed with error %d\n", prop, err); 240 } 241 242 return err; 243 } 244