acpi.h

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/* Copyright (c) 2010 Wildfire Games
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

/*
 * minimal subset of ACPI
 */

#ifndef INCLUDED_ACPI
#define INCLUDED_ACPI

#pragma pack(push, 1)

// common header for all ACPI tables
struct AcpiTable
{
    char signature[4];
    u32 size;                   // table size [bytes], including header
    u8 revision;
    u8 checksum;                // to make sum of entire table == 0
    char oemId[6];
    char oemTableId[8];
    u32 oemRevision;
    char creatorId[4];
    u32 creatorRevision;
};

enum AcpiAddressSpace
{
    // (these are not generally powers-of-two - some values have been omitted.)
    ACPI_AS_MEMORY     = 0,
    ACPI_AS_IO         = 1,
    ACPI_AS_PCI_CONFIG = 2,
    ACPI_AS_SMBUS      = 4
};

// address of a struct or register
struct AcpiGenericAddress
{
    u8 addressSpaceId;
    u8 registerBitWidth;
    u8 registerBitOffset;
    u8 accessSize;
    u64 address;
};

struct FADT // signature is FACP!
{
    AcpiTable header;
    u8 unused1[40];
    u32 pmTimerPortAddress;
    u8 unused2[16];
    u16 c2Latency;  // [us]
    u16 c3Latency;  // [us]
    u8 unused3[5];
    u8 dutyWidth;
    u8 unused4[6];
    u32 flags;
    // (ACPI4 defines additional fields after this)

    bool IsDutyCycleSupported() const
    {
        return dutyWidth != 0;
    }

    bool IsC2Supported() const
    {
        return c2Latency <= 100;    // magic value specified by ACPI
    }

    bool IsC3Supported() const
    {
        return c3Latency <= 1000;   // see above
    }
};

#pragma pack(pop)

/**
 * @param signature e.g. "RSDT"
 * @return pointer to internal storage (valid until acpi_Shutdown())
 *
 * note: the first call may be slow, e.g. if a kernel-mode driver is
 * loaded. subsequent requests will be faster since tables are cached.
 **/
LIB_API const AcpiTable* acpi_GetTable(const char* signature);

/**
 * invalidates all pointers returned by acpi_GetTable.
 **/
LIB_API void acpi_Shutdown();

#endif  // #ifndef INCLUDED_ACPI