acpipwr.c File Reference

ACPI power off. More...

#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <byteswap.h>
#include <ipxe/io.h>
#include <ipxe/acpi.h>
#include <ipxe/acpipwr.h>

Go to the source code of this file.

Macros
#define	colour   FADT_SIGNATURE
	Colour for debug messages. More...
#define	S5_SIGNATURE   ACPI_SIGNATURE ( '_', 'S', '5', '_' )
	S5 signature More...

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
static int	acpi_extract_sx (const struct acpi_header *zsdt, size_t len, size_t offset, void *data)
	Extract _Sx value from DSDT/SSDT. More...
int	acpi_poweroff (void)
	Power off the computer using ACPI. More...

Detailed Description

ACPI power off.

Definition in file acpipwr.c.

Macro Definition Documentation

colour

#define colour   FADT_SIGNATURE

Colour for debug messages.

Definition at line 41 of file acpipwr.c.

S5_SIGNATURE

#define S5_SIGNATURE   ACPI_SIGNATURE ( '_', 'S', '5', '_' )

S5 signature

Definition at line 44 of file acpipwr.c.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER_OR_UBDL

)

acpi_extract_sx()

static int acpi_extract_sx ( const struct acpi_header *  zsdt, size_t  len, size_t  offset, void *  data  )

static

Extract _Sx value from DSDT/SSDT.

Parameters

zsdt	DSDT or SSDT
len	Length of DSDT/SSDT
offset	Offset of signature within DSDT/SSDT
data	Data buffer

Return values

rc	Return status code

In theory, extracting the _Sx value from the DSDT/SSDT requires a full ACPI parser plus some heuristics to work around the various broken encodings encountered in real ACPI implementations.

In practice, we can get the same result by scanning through the DSDT/SSDT for the signature (e.g. "_S5_"), extracting the first four bytes, removing any bytes with bit 3 set, and treating whatever is left as a little-endian value. This is one of the uglier hacks I have ever implemented, but it's still prettier than the ACPI specification itself.

Definition at line 66 of file acpipwr.c.

                                                         {
        unsigned int *sx = data;
        uint8_t bytes[4];
        uint8_t *byte;

        /* Skip signature and package header */
        offset += ( 4 /* signature */ + 3 /* package header */ );

        /* Sanity check */
        if ( ( offset + sizeof ( bytes ) /* value */ ) > len ) {
                return -EINVAL;
        }

        /* Read first four bytes of value */
        memcpy ( bytes, ( ( ( const void * ) zsdt ) + offset ),
                 sizeof ( bytes ) );
        DBGC ( colour, "ACPI found \\_Sx containing %02x:%02x:%02x:%02x\n",
               bytes[0], bytes[1], bytes[2], bytes[3] );

        /* Extract \Sx value.  There are three potential encodings
         * that we might encounter:
         *
         * - SLP_TYPa, SLP_TYPb, rsvd, rsvd
         *
         * - <byteprefix>, SLP_TYPa, <byteprefix>, SLP_TYPb, ...
         *
         * - <dwordprefix>, SLP_TYPa, SLP_TYPb, 0, 0
         *
         * Since <byteprefix> and <dwordprefix> both have bit 3 set,
         * and valid SLP_TYPx must have bit 3 clear (since SLP_TYPx is
         * a 3-bit field), we can just skip any bytes with bit 3 set.
         */
        byte = bytes;
        if ( *byte & 0x08 )
                byte++;
        *sx = *(byte++);
        if ( *byte & 0x08 )
                byte++;
        *sx |= ( *byte << 8 );

        return 0;
}

References bytes, colour, data, DBGC, EINVAL, len, memcpy(), and offset.

Referenced by acpi_poweroff().

acpi_poweroff()

int acpi_poweroff

(

void

)

Power off the computer using ACPI.

Return values

rc	Return status code

Definition at line 115 of file acpipwr.c.

                           {
        const struct acpi_fadt *fadt;
        unsigned int pm1a_cnt_blk;
        unsigned int pm1b_cnt_blk;
        unsigned int pm1a_cnt;
        unsigned int pm1b_cnt;
        unsigned int slp_typa;
        unsigned int slp_typb;
        unsigned int s5;
        int rc;

        /* Locate FADT */
        fadt = container_of ( acpi_table ( FADT_SIGNATURE, 0 ),
                              struct acpi_fadt, acpi );
        if ( ! fadt ) {
                DBGC ( colour, "ACPI could not find FADT\n" );
                return -ENOENT;
        }

        /* Read FADT */
        pm1a_cnt_blk = le32_to_cpu ( fadt->pm1a_cnt_blk );
        pm1b_cnt_blk = le32_to_cpu ( fadt->pm1b_cnt_blk );
        pm1a_cnt = ( pm1a_cnt_blk + ACPI_PM1_CNT );
        pm1b_cnt = ( pm1b_cnt_blk + ACPI_PM1_CNT );

        /* Extract \_S5 from DSDT or any SSDT */
        if ( ( rc = acpi_extract ( S5_SIGNATURE, &s5,
                                   acpi_extract_sx ) ) != 0 ) {
                DBGC ( colour, "ACPI could not extract \\_S5: %s\n",
                       strerror ( rc ) );
                return rc;
        }

        /* Power off system */
        if ( pm1a_cnt_blk ) {
                slp_typa = ( ( s5 >> 0 ) & 0xff );
                DBGC ( colour, "ACPI PM1a sleep type %#x => %04x\n",
                       slp_typa, pm1a_cnt );
                outw ( ( ACPI_PM1_CNT_SLP_TYP ( slp_typa ) |
                         ACPI_PM1_CNT_SLP_EN ), pm1a_cnt );
        }
        if ( pm1b_cnt_blk ) {
                slp_typb = ( ( s5 >> 8 ) & 0xff );
                DBGC ( colour, "ACPI PM1b sleep type %#x => %04x\n",
                       slp_typb, pm1b_cnt );
                outw ( ( ACPI_PM1_CNT_SLP_TYP ( slp_typb ) |
                         ACPI_PM1_CNT_SLP_EN ), pm1b_cnt );
        }

        /* On some systems, execution will continue briefly.  Delay to
         * avoid potentially confusing log messages.
         */
        mdelay ( 1000 );

        DBGC ( colour, "ACPI power off failed\n" );
        return -EPROTO;
}

References acpi, acpi_extract(), acpi_extract_sx(), ACPI_PM1_CNT, ACPI_PM1_CNT_SLP_EN, ACPI_PM1_CNT_SLP_TYP, acpi_table(), colour, container_of, DBGC, ENOENT, EPROTO, FADT_SIGNATURE, le32_to_cpu, mdelay(), outw, acpi_fadt::pm1a_cnt_blk, acpi_fadt::pm1b_cnt_blk, rc, S5_SIGNATURE, and strerror().

Referenced by bios_poweroff().