diff options
Diffstat (limited to 'lib/smbios-parser.c')
-rw-r--r-- | lib/smbios-parser.c | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/lib/smbios-parser.c b/lib/smbios-parser.c new file mode 100644 index 0000000000..b89f988ef9 --- /dev/null +++ b/lib/smbios-parser.c @@ -0,0 +1,96 @@ +// 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); +} |