system76-coreboot/util/nvramtool/coreboot_tables.h

/*****************************************************************************\
 * coreboot_tables.h
\*****************************************************************************/

#ifndef COREBOOT_TABLES_H
#define COREBOOT_TABLES_H

#include <stdint.h>

/* Note: The contents of this file were borrowed from the coreboot source
 * code which may be obtained from https://www.coreboot.org/.
 * Specifically, this code was obtained from LinuxBIOS version 1.1.8.
 */

/* The coreboot table information is for conveying information
 * from the firmware to the loaded OS image. Primarily this
 * is expected to be information that cannot be discovered by
 * other means, such as querying the hardware directly.
 *
 * All of the information should be Position Independent Data.
 * That is, it should be safe to relocate any of the information
 * without changing its meaning/correctness. For tables that
 * can reasonably be used on multiple architectures the data
 * size should be fixed. This should ease the transition between
 * 32 bit and 64 bit architectures etc.
 *
 * The completeness test for the information in this table is:
 * - Can all of the hardware be detected?
 * - Are the per-motherboard constants available?
 * - Is there enough to allow a kernel to run that was written before
 *   a particular motherboard is constructed? (Assuming the kernel
 *   has drivers for all of the hardware but it does not have
 *   assumptions on how the hardware is connected together).
 *
 * With this test it should be straightforward to determine if a
 * table entry is required or not. This should remove much of the
 * long-term compatibility burden as table entries which are
 * irrelevant or have been replaced by better alternatives may be
 * dropped. Of course it is polite and expedite to include extra
 * table entries and be backwards compatible, but it is not required.
 */

/* Since coreboot is usually compiled 32bit, gcc will align 64bit
 * types to 32bit boundaries. If the coreboot table is dumped on a
 * 64bit system, a uint64_t would be aligned to 64bit boundaries,
 * breaking the table format.
 *
 * lb_uint64_t will keep 64bit coreboot table values aligned to 32bit
 * to ensure compatibility.
 */

typedef __attribute__((aligned(4))) uint64_t lb_uint64_t;

struct lb_header {
	union {
		uint8_t signature[4];	/* LBIO */
		uint32_t signature32;
	};
	uint32_t header_bytes;
	uint32_t header_checksum;
	uint32_t table_bytes;
	uint32_t table_checksum;
	uint32_t table_entries;
};

/* Every entry in the boot environment list will correspond to a boot
 * info record, encoding both type and size. The type is obviously
 * so you can tell what it is. The size allows you to skip that
 * boot environment record if you don't know what it is. This allows
 * forward compatibility with records not yet defined.
 */
struct lb_record {
	uint32_t tag;		/* tag ID */
	uint32_t size;		/* size of record (in bytes) */
};

#define LB_TAG_UNUSED		0x0000

#define LB_TAG_MEMORY		0x0001

struct lb_memory_range {
	lb_uint64_t start;
	lb_uint64_t size;
	uint32_t type;
#define LB_MEM_RAM	1	/* Memory anyone can use */
#define LB_MEM_RESERVED	2	/* Don't use this memory region */
#define LB_MEM_TABLE	16	/* RAM configuration tables are kept in */
};

struct lb_memory {
	uint32_t tag;
	uint32_t size;
	struct lb_memory_range map[];
};

#define LB_TAG_HWRPB		0x0002
struct lb_hwrpb {
	uint32_t tag;
	uint32_t size;
	uint64_t hwrpb;
};

#define LB_TAG_MAINBOARD	0x0003
struct lb_mainboard {
	uint32_t tag;
	uint32_t size;
	uint8_t vendor_idx;
	uint8_t part_number_idx;
	uint8_t strings[];
};

#define LB_TAG_VERSION		0x0004
#define LB_TAG_EXTRA_VERSION	0x0005
#define LB_TAG_BUILD		0x0006
#define LB_TAG_COMPILE_TIME	0x0007
#define LB_TAG_COMPILE_BY	0x0008
#define LB_TAG_COMPILE_HOST	0x0009
#define LB_TAG_COMPILE_DOMAIN	0x000a
#define LB_TAG_COMPILER		0x000b
#define LB_TAG_LINKER		0x000c
#define LB_TAG_ASSEMBLER	0x000d
struct lb_string {
	uint32_t tag;
	uint32_t size;
	uint8_t string[];
};
#define LB_TAG_SERIAL		0x000f
#define LB_TAG_CONSOLE		0x0010
#define LB_TAG_FORWARD		0x0011
struct lb_forward {
	uint32_t tag;
	uint32_t size;
	uint64_t forward;
};

/* The following structures are for the CMOS definitions table */
#define LB_TAG_CMOS_OPTION_TABLE 200
/* CMOS header record */
struct cmos_option_table {
	uint32_t tag;		/* CMOS definitions table type */
	uint32_t size;		/* size of the entire table */
	uint32_t header_length;	/* length of header */
};

/* CMOS entry record
 * This record has a variable length. The name field may be
 * shorter than CMOS_MAX_NAME_LENGTH. The entry may start
 * anywhere in the byte, but can not span bytes unless it
 * starts at the beginning of the byte and the length
 * fills complete bytes.
 */
#define LB_TAG_OPTION 201
struct cmos_entries {
	uint32_t tag;		/* entry type */
	uint32_t size;		/* length of this record */
	uint32_t bit;		/* starting bit from start of image */
	uint32_t length;	/* length of field in bits */
	uint32_t config;	/* e=enumeration, h=hex, r=reserved */
	uint32_t config_id;	/* a number linking to an enumeration record */
#define CMOS_MAX_NAME_LENGTH 32
	uint8_t name[CMOS_MAX_NAME_LENGTH];	/* name of entry in ascii,
						   variable length int aligned */
};

/* CMOS enumerations record
 * This record has a variable length. The text field may be
 * shorter than CMOS_MAX_TEXT_LENGTH.
 */
#define LB_TAG_OPTION_ENUM 202
struct cmos_enums {
	uint32_t tag;		/* enumeration type */
	uint32_t size;		/* length of this record */
	uint32_t config_id;	/* a number identifying the config id */
	uint32_t value;		/* the value associated with the text */
#define CMOS_MAX_TEXT_LENGTH 32
	uint8_t text[CMOS_MAX_TEXT_LENGTH];	/* enum description in ascii,
						   variable length int aligned */
};

/* CMOS default record
 * This record contains default settings for the CMOS RAM.
 */
#define LB_TAG_OPTION_DEFAULTS 203
struct cmos_defaults {
	uint32_t tag;		/* default type */
	uint32_t size;		/* length of this record */
	uint32_t name_length;	/* length of the following name field */
	uint8_t name[CMOS_MAX_NAME_LENGTH];	/* name identifying the default */
#define CMOS_IMAGE_BUFFER_SIZE 128
	uint8_t default_set[CMOS_IMAGE_BUFFER_SIZE];	/* default settings */
};

#define LB_TAG_OPTION_CHECKSUM 204
struct cmos_checksum {
	uint32_t tag;
	uint32_t size;
	/* In practice everything is byte aligned, but things are measured
	 * in bits to be consistent.
	 */
	uint32_t range_start;	/* First bit that is checksummed (byte aligned) */
	uint32_t range_end;	/* Last bit that is checksummed (byte aligned) */
	uint32_t location;	/* First bit of the checksum (byte aligned) */
	uint32_t type;		/* Checksum algorithm that is used */
#define CHECKSUM_NONE	0
#define CHECKSUM_PCBIOS	1
};

#endif				/* COREBOOT_TABLES_H */