/* SPDX-License-Identifier: BSD-2-Clause */
// Written by SASANO Takayoshi

#include <stdio.h>
#include <string.h>

#include "crc32.h"
#include "uboot_glue.h"

extern uint32_t	search_hint;
extern void *syscall_ptr;

static int check_signature(struct api_signature *signature)
{
	uint32_t crc;
	struct api_signature s;

	if (signature != NULL) {
		s = *signature;
		s.checksum = 0;

		crc = crc32((uint8_t *)&s, sizeof(s));

		if (crc == signature->checksum)
			return 1;
	}

	return 0;
}

static struct api_signature *find_signature(void)
{
	void *search_top, *search_end, *sp;

	/* search range: default stack pointer ~ 3MBytes */
	search_top = (void *)(search_hint & 0xfff00000);
	search_end = (void *)
		(search_top + 0x00300000 - sizeof(struct api_signature));

	for (sp = search_top; sp < search_end; sp += API_SIG_MAGLEN) {
		if (!memcmp(sp, API_SIG_MAGIC, API_SIG_MAGLEN) &&
		    check_signature(sp))
			return sp;
	}

	return NULL;
}

int init_uboot_syscall(void)
{
	struct api_signature *s;

	s = find_signature();
	if (s != NULL) {
		syscall_ptr = s->syscall;
		return 0;
	} else {
		syscall_ptr = NULL;
		return -1;
	}
}