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