rsdp.c File Reference

ACPI Root System Description Pointer. More...

#include <stdint.h>
#include <string.h>
#include <realmode.h>
#include <bios.h>
#include <ipxe/acpi.h>
#include <ipxe/rsdp.h>

Go to the source code of this file.

Macros
#define	RSDP_EBDA_END_SEG   0xa000
	EBDA RSDP maximum segment. More...
#define	RSDP_BIOS_START   0xe0000
	Fixed BIOS area RSDP start address. More...
#define	RSDP_BIOS_LEN   0x20000
	Fixed BIOS area RSDP length. More...
#define	RSDP_STRIDE   16
	Stride at which to search for RSDP. More...

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
static const struct acpi_rsdt *	rsdp_find_rsdt_range (const void *start, size_t len)
	Locate ACPI root system description table within a memory range. More...
static const struct acpi_rsdt *	rsdp_find_rsdt (void)
	Locate ACPI root system description table. More...
	PROVIDE_ACPI (rsdp, acpi_find_rsdt, rsdp_find_rsdt)
	PROVIDE_ACPI_INLINE (rsdp, acpi_find)

Detailed Description

ACPI Root System Description Pointer.

Definition in file rsdp.c.

Macro Definition Documentation

RSDP_EBDA_END_SEG

#define RSDP_EBDA_END_SEG   0xa000

EBDA RSDP maximum segment.

Definition at line 41 of file rsdp.c.

RSDP_BIOS_START

#define RSDP_BIOS_START   0xe0000

Fixed BIOS area RSDP start address.

Definition at line 44 of file rsdp.c.

RSDP_BIOS_LEN

#define RSDP_BIOS_LEN   0x20000

Fixed BIOS area RSDP length.

Definition at line 47 of file rsdp.c.

RSDP_STRIDE

#define RSDP_STRIDE   16

Stride at which to search for RSDP.

Definition at line 50 of file rsdp.c.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER_OR_UBDL

)

rsdp_find_rsdt_range()

static const struct acpi_rsdt* rsdp_find_rsdt_range ( const void *  start, size_t  len  )

static

Locate ACPI root system description table within a memory range.

Parameters

start	Start address to search
len	Length to search

Return values

rsdt	ACPI root system description table, or NULL

Definition at line 59 of file rsdp.c.

                                                                    {
        static const char signature[8] = RSDP_SIGNATURE;
        const struct acpi_rsdp *rsdp;
        const struct acpi_rsdt *rsdt;
        size_t offset;
        uint8_t sum;
        unsigned int i;

        /* Search for RSDP */
        for ( offset = 0 ; ( ( offset + sizeof ( *rsdp ) ) < len ) ;
              offset += RSDP_STRIDE ) {

                /* Check signature and checksum */
                rsdp = ( start + offset );
                if ( memcmp ( rsdp->signature, signature,
                              sizeof ( signature ) ) != 0 )
                        continue;
                for ( sum = 0, i = 0 ; i < sizeof ( *rsdp ) ; i++ )
                        sum += *( ( ( uint8_t * ) rsdp ) + i );
                if ( sum != 0 )
                        continue;

                /* Extract RSDT */
                rsdt = phys_to_virt ( le32_to_cpu ( rsdp->rsdt ) );
                DBGC ( rsdt, "RSDT %#08lx found via RSDP %#08lx\n",
                       virt_to_phys ( rsdt ),
                       ( virt_to_phys ( start ) + offset ) );
                return rsdt;
        }

        return NULL;
}

References DBGC, le32_to_cpu, len, memcmp(), NULL, offset, rsdp, RSDP_SIGNATURE, RSDP_STRIDE, signature, and start.

Referenced by rsdp_find_rsdt().

rsdp_find_rsdt()

static const struct acpi_rsdt* rsdp_find_rsdt ( void  )

static

Locate ACPI root system description table.

Return values

rsdt	ACPI root system description table, or NULL

Definition at line 98 of file rsdp.c.

                                                        {
        static const struct acpi_rsdt *rsdt;
        const void *ebda;
        uint16_t ebda_seg;
        size_t ebda_len;

        /* Return existing RSDT if already found */
        if ( rsdt )
                return rsdt;

        /* Search EBDA */
        get_real ( ebda_seg, BDA_SEG, BDA_EBDA );
        if ( ebda_seg < RSDP_EBDA_END_SEG ) {
             ebda = real_to_virt ( ebda_seg, 0 );
             ebda_len = ( ( RSDP_EBDA_END_SEG - ebda_seg ) * 16 );
             rsdt = rsdp_find_rsdt_range ( ebda, ebda_len );
             if ( rsdt )
                     return rsdt;
        }

        /* Search fixed BIOS area */
        rsdt = rsdp_find_rsdt_range ( phys_to_virt ( RSDP_BIOS_START ),
                                      RSDP_BIOS_LEN );
        if ( rsdt )
                return rsdt;

        return NULL;
}

References BDA_EBDA, BDA_SEG, get_real, NULL, real_to_virt(), RSDP_BIOS_LEN, RSDP_BIOS_START, RSDP_EBDA_END_SEG, and rsdp_find_rsdt_range().

PROVIDE_ACPI()

PROVIDE_ACPI	(	rsdp	,
		acpi_find_rsdt	,
		rsdp_find_rsdt
	)

PROVIDE_ACPI_INLINE()

PROVIDE_ACPI_INLINE	(	rsdp	,
		acpi_find
	)