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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 <debug.h>
#include <fdt_wrappers.h>
#include <libfdt.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;
}
/*
* 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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