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- // SPDX-License-Identifier: GPL-2.0+
- /*
- * Copyright (C) 2020, Bachmann electronic GmbH
- */
- #include <common.h>
- #include <smbios.h>
- static inline int verify_checksum(const struct smbios_entry *e)
- {
- /*
- * Checksums for SMBIOS tables are calculated to have a value, so that
- * the sum over all bytes yields zero (using unsigned 8 bit arithmetic).
- */
- u8 *byte = (u8 *)e;
- u8 sum = 0;
- for (int i = 0; i < e->length; i++)
- sum += byte[i];
- return sum;
- }
- const struct smbios_entry *smbios_entry(u64 address, u32 size)
- {
- const struct smbios_entry *entry = (struct smbios_entry *)(uintptr_t)address;
- if (!address | !size)
- return NULL;
- if (memcmp(entry->anchor, "_SM_", 4))
- return NULL;
- if (verify_checksum(entry))
- return NULL;
- return entry;
- }
- static const struct smbios_header *next_header(const struct smbios_header *curr)
- {
- u8 *pos = ((u8 *)curr) + curr->length;
- /* search for _double_ NULL bytes */
- while (!((*pos == 0) && (*(pos + 1) == 0)))
- pos++;
- /* step behind the double NULL bytes */
- pos += 2;
- return (struct smbios_header *)pos;
- }
- const struct smbios_header *smbios_header(const struct smbios_entry *entry, int type)
- {
- const unsigned int num_header = entry->struct_count;
- const struct smbios_header *header = (struct smbios_header *)entry->struct_table_address;
- for (unsigned int i = 0; i < num_header; i++) {
- if (header->type == type)
- return header;
- header = next_header(header);
- }
- return NULL;
- }
- static const char *string_from_smbios_table(const struct smbios_header *header,
- int idx)
- {
- unsigned int i = 1;
- u8 *pos;
- if (!header)
- return NULL;
- pos = ((u8 *)header) + header->length;
- while (i < idx) {
- if (*pos == 0x0)
- i++;
- pos++;
- }
- return (const char *)pos;
- }
- const char *smbios_string(const struct smbios_header *header, int index)
- {
- if (!header)
- return NULL;
- return string_from_smbios_table(header, index);
- }
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