#ifndef _ASM_X86_BIOS_EBDA_H
#define _ASM_X86_BIOS_EBDA_H

#include <asm/io.h>

/*
* Returns physical address of EBDA. Returns 0 if there is no EBDA.
*/
static inline unsigned int get_bios_ebda(void)
{
/*
* There is a real-mode segmented pointer pointing to the
* 4K EBDA area at 0x40E.
*/
unsigned int address = *(unsigned short *)phys_to_virt(0x40E);
address <<= 4;
return address; /* 0 means none */
}

/*
* Return the sanitized length of the EBDA in bytes, if it exists.
*/
static inline unsigned int get_bios_ebda_length(void)
{
unsigned int address;
unsigned int length;

address = get_bios_ebda();
if (!address)
return 0;

/* EBDA length is byte 0 of the EBDA (stored in KiB) */
length = *(unsigned char *)phys_to_virt(address);
length <<= 10;

/* Trim the length if it extends beyond 640KiB */
length = min_t(unsigned int, (640 * 1024) - address, length);
return length;
}

void reserve_ebda_region(void);

#ifdef CONFIG_X86_CHECK_BIOS_CORRUPTION
/*
* This is obviously not a great place for this, but we want to be
* able to scatter it around anywhere in the kernel.
*/
void check_for_bios_corruption(void);
void start_periodic_check_for_corruption(void);
#else
static inline void check_for_bios_corruption(void)
{
}

static inline void start_periodic_check_for_corruption(void)
{
}
#endif

#endif /* _ASM_X86_BIOS_EBDA_H */