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96 lines
2.2 KiB
96 lines
2.2 KiB
/*
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* Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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/* Helper functions to offer easier navigation of Device Tree Blob */
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#include <assert.h>
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#include <debug.h>
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#include <fdt_wrappers.h>
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#include <libfdt.h>
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/*
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* Read cells from a given property of the given node. At most 2 cells of the
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* property are read, and pointer is updated. Returns 0 on success, and -1 upon
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* error
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*/
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int fdtw_read_cells(const void *dtb, int node, const char *prop,
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unsigned int cells, void *value)
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{
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const uint32_t *value_ptr;
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uint32_t hi = 0, lo;
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int value_len;
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assert(dtb != NULL);
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assert(prop != NULL);
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assert(value != NULL);
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assert(node >= 0);
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/* We expect either 1 or 2 cell property */
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assert(cells <= 2U);
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/* Access property and obtain its length (in bytes) */
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value_ptr = fdt_getprop_namelen(dtb, node, prop, (int)strlen(prop),
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&value_len);
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if (value_ptr == NULL) {
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WARN("Couldn't find property %s in dtb\n", prop);
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return -1;
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}
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/* Verify that property length accords with cell length */
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if (NCELLS((unsigned int)value_len) != cells) {
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WARN("Property length mismatch\n");
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return -1;
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}
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if (cells == 2U) {
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hi = fdt32_to_cpu(*value_ptr);
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value_ptr++;
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}
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lo = fdt32_to_cpu(*value_ptr);
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if (cells == 2U)
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*((uint64_t *) value) = ((uint64_t) hi << 32) | lo;
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else
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*((uint32_t *) value) = lo;
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return 0;
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}
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/*
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* Write cells in place to a given property of the given node. At most 2 cells
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* of the property are written. Returns 0 on success, and -1 upon error.
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*/
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int fdtw_write_inplace_cells(void *dtb, int node, const char *prop,
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unsigned int cells, void *value)
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{
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int err, len;
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assert(dtb != NULL);
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assert(prop != NULL);
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assert(value != NULL);
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assert(node >= 0);
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/* We expect either 1 or 2 cell property */
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assert(cells <= 2U);
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if (cells == 2U)
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*(uint64_t *)value = cpu_to_fdt64(*(uint64_t *)value);
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else
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*(uint32_t *)value = cpu_to_fdt32(*(uint32_t *)value);
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len = (int)cells * 4;
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/* Set property value in place */
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err = fdt_setprop_inplace(dtb, node, prop, value, len);
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if (err != 0) {
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WARN("Modify property %s failed with error %d\n", prop, err);
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return -1;
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}
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return 0;
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}
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