1 /* 2 * Copyright (c) 2018, 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. The fdt pointer is updated. Returns 0 on 69 * success, and -1 on error. 70 */ 71 int fdtw_read_array(const void *dtb, int node, const char *prop, 72 unsigned int cells, void *value) 73 { 74 const uint32_t *value_ptr; 75 int value_len; 76 77 assert(dtb != NULL); 78 assert(prop != NULL); 79 assert(value != NULL); 80 assert(node >= 0); 81 82 /* Access property and obtain its length (in bytes) */ 83 value_ptr = fdt_getprop_namelen(dtb, node, prop, (int)strlen(prop), 84 &value_len); 85 if (value_ptr == NULL) { 86 WARN("Couldn't find property %s in dtb\n", prop); 87 return -1; 88 } 89 90 /* Verify that property length accords with cell length */ 91 if (NCELLS((unsigned int)value_len) != cells) { 92 WARN("Property length mismatch\n"); 93 return -1; 94 } 95 96 uint32_t *dst = value; 97 98 for (unsigned int i = 0U; i < cells; i++) { 99 dst[i] = fdt32_to_cpu(value_ptr[i]); 100 } 101 102 return 0; 103 } 104 105 /* 106 * Read string from a given property of the given node. Up to 'size - 1' 107 * characters are read, and a NUL terminator is added. Returns 0 on success, 108 * and -1 upon error. 109 */ 110 int fdtw_read_string(const void *dtb, int node, const char *prop, 111 char *str, size_t size) 112 { 113 const char *ptr; 114 size_t len; 115 116 assert(dtb != NULL); 117 assert(node >= 0); 118 assert(prop != NULL); 119 assert(str != NULL); 120 assert(size > 0U); 121 122 ptr = fdt_getprop_namelen(dtb, node, prop, (int)strlen(prop), NULL); 123 if (ptr == NULL) { 124 WARN("Couldn't find property %s in dtb\n", prop); 125 return -1; 126 } 127 128 len = strlcpy(str, ptr, size); 129 if (len >= size) { 130 WARN("String of property %s in dtb has been truncated\n", prop); 131 return -1; 132 } 133 134 return 0; 135 } 136 137 /* 138 * Write cells in place to a given property of the given node. At most 2 cells 139 * of the property are written. Returns 0 on success, and -1 upon error. 140 */ 141 int fdtw_write_inplace_cells(void *dtb, int node, const char *prop, 142 unsigned int cells, void *value) 143 { 144 int err, len; 145 146 assert(dtb != NULL); 147 assert(prop != NULL); 148 assert(value != NULL); 149 assert(node >= 0); 150 151 /* We expect either 1 or 2 cell property */ 152 assert(cells <= 2U); 153 154 if (cells == 2U) 155 *(uint64_t *)value = cpu_to_fdt64(*(uint64_t *)value); 156 else 157 *(uint32_t *)value = cpu_to_fdt32(*(uint32_t *)value); 158 159 len = (int)cells * 4; 160 161 /* Set property value in place */ 162 err = fdt_setprop_inplace(dtb, node, prop, value, len); 163 if (err != 0) { 164 WARN("Modify property %s failed with error %d\n", prop, err); 165 return -1; 166 } 167 168 return 0; 169 } 170