u-boot/arch/x86/include/asm/mrccache.h

/*
 * Copyright (C) 2014 Google, Inc
 * Copyright (C) 2015 Bin Meng <bmeng.cn@gmail.com>
 *
 * SPDX-License-Identifier:	GPL-2.0+
 */

#ifndef _ASM_MRCCACHE_H
#define _ASM_MRCCACHE_H

#define MRC_DATA_ALIGN		0x1000
#define MRC_DATA_SIGNATURE	(('M' << 0) | ('R' << 8) | \
				 ('C' << 16) | ('D'<<24))

#define MRC_DATA_HEADER_SIZE	32

struct __packed mrc_data_container {
	u32	signature;	/* "MRCD" */
	u32	data_size;	/* Size of the 'data' field */
	u32	checksum;	/* IP style checksum */
	u32	reserved;	/* For header alignment */
	u8	data[0];	/* Variable size, platform/run time dependent */
};

struct mrc_region {
	u32	base;
	u32	offset;
	u32	length;
};

struct udevice;

/**
 * mrccache_find_current() - find the latest MRC cache record
 *
 * This searches the MRC cache region looking for the latest record to use
 * for setting up SDRAM
 *
 * @entry:	Position and size of MRC cache in SPI flash
 * @return pointer to latest record, or NULL if none
 */
struct mrc_data_container *mrccache_find_current(struct mrc_region *entry);

/**
 * mrccache_update() - update the MRC cache with a new record
 *
 * This writes a new record to the end of the MRC cache region. If the new
 * record is the same as the latest record then the write is skipped
 *
 * @sf:		SPI flash to write to
 * @entry:	Position and size of MRC cache in SPI flash
 * @cur:	Record to write
 * @return 0 if updated, -EEXIST if the record is the same as the latest
 * record, -EINVAL if the record is not valid, other error if SPI write failed
 */
int mrccache_update(struct udevice *sf, struct mrc_region *entry,
		    struct mrc_data_container *cur);

/**
 * mrccache_reserve() - reserve MRC data on the stack
 *
 * This copies MRC data pointed by gd->arch.mrc_output to a new place on the
 * stack with length gd->arch.mrc_output_len, and updates gd->arch.mrc_output
 * to point to the new place once the migration is done.
 *
 * This routine should be called by reserve_arch() before U-Boot is relocated
 * when MRC cache is enabled.
 *
 * @return 0 always
 */
int mrccache_reserve(void);

/**
 * mrccache_get_region() - get MRC region on the SPI flash
 *
 * This gets MRC region whose offset and size are described in the device tree
 * as a subnode to the SPI flash. If a non-NULL device pointer is supplied,
 * this also probes the SPI flash device and returns its device pointer for
 * the caller to use later.
 *
 * Be careful when calling this routine with a non-NULL device pointer:
 * - driver model initialization must be complete
 * - calling in the pre-relocation phase may bring some side effects during
 *   the SPI flash device probe (eg: for SPI controllers on a PCI bus, it
 *   triggers PCI bus enumeration during which insufficient memory issue
 *   might be exposed and it causes subsequent SPI flash probe fails).
 *
 * @devp:	Returns pointer to the SPI flash device
 * @entry:	Position and size of MRC cache in SPI flash
 * @return 0 if success, -ENOENT if SPI flash node does not exist in the
 * device tree, -EPERM if MRC region subnode does not exist in the device
 * tree, -EINVAL if MRC region properties format is incorrect, other error
 * if SPI flash probe failed.
 */
int mrccache_get_region(struct udevice **devp, struct mrc_region *entry);

/**
 * mrccache_save() - save MRC data to the SPI flash
 *
 * This saves MRC data stored previously by gd->arch.mrc_output to a proper
 * place within the MRC region on the SPI flash.
 *
 * @return 0 if saved to SPI flash successfully, other error if failed
 */
int mrccache_save(void);

#endif /* _ASM_MRCCACHE_H */