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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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