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- /*
- * 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;
- }
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