Luna/kernel/src/acpi/RSDT.cpp

#define MODULE "acpi/rsdt"

#include "acpi/RSDT.h"
#include "bootboot.h"
#include "log/Address.h"
#include "log/Log.h"
#include "memory/KernelMemoryManager.h"
#include "std/stdio.h"
#include "std/string.h"

extern BOOTBOOT bootboot;

ACPI::SDTHeader* ACPI::GetRSDTOrXSDT()
{
    static void* cache = nullptr;
    if (cache) return (SDTHeader*)cache;
    kinfoln("First time accessing the RSDT/XSDT, mapping it into memory");
    void* physical = (void*)bootboot.arch.x86_64.acpi_ptr;
    uint64_t offset = (uint64_t)physical % 4096;
    kinfoln("RSDT/XSDT physical address: %lx", (uint64_t)physical);
    cache = KernelMemoryManager::get_unaligned_mapping(physical);
    uint64_t numPages = 1;
    while ((offset + ((SDTHeader*)cache)->Length) > (numPages * 4096))
    {
        kinfoln("RSDT/XSDT extends beyond the mapped page, mapping one more page");
        KernelMemoryManager::release_unaligned_mappings(cache, numPages);
        numPages++;
        cache = KernelMemoryManager::get_unaligned_mappings(cache, numPages);
    }
    kinfoln("Mapped RSDT/XSDT to virtual address %lx, uses %ld pages", (uint64_t)cache, numPages);
    SDTHeader* result = (SDTHeader*)cache;
    char OEMID[7];
    memcpy(OEMID, result->OEMID, 6);
    OEMID[6] = 0;
    kinfoln("OEMID: %s", OEMID);
    char OEMTableID[9];
    memcpy(OEMTableID, result->OEMTableID, 8);
    OEMTableID[8] = 0;
    kinfoln("OEMTableID: %s", OEMTableID);
    return result;
}

bool ACPI::ValidateRSDTOrXSDT(ACPI::SDTHeader* rootSDT)
{
    if (!ValidateSDTHeader(rootSDT)) return false;
    if (strncmp(rootSDT->Signature, "XSDT", 4) == 0) return true;
    if (strncmp(rootSDT->Signature, "RSDT", 4) == 0) return true;
    return false;
}

bool ACPI::IsXSDT(ACPI::SDTHeader* rootSDT)
{
    return strncmp(rootSDT->Signature, "XSDT", 4) == 0;
}

void* ACPI::FindTable(ACPI::SDTHeader* rootSDT, const char* signature)
{
    bool isXSDT = (strncmp(rootSDT->Signature, "XSDT", 4) == 0);
    int entries = (rootSDT->Length - sizeof(SDTHeader)) / (isXSDT ? 8 : 4);
    kinfoln("Searching for table %s in the %s at %lx (table contains %d entries)", signature, isXSDT ? "XSDT" : "RSDT",
            (uint64_t)rootSDT, entries);

    for (int i = 0; i < entries; i++)
    {
        kinfoln("Testing for table %s in entry %d", signature, i);
        SDTHeader* h;
        if (isXSDT)
        {
            uint64_t reversedAddress = (uint64_t)((XSDT*)rootSDT)->PointerToOtherSDT[i];
            uint64_t correctAddress = reversedAddress >> 32 | reversedAddress << 32;
            h = (SDTHeader*)correctAddress;
        }
        else
        {
            uint32_t entry = ((RSDT*)rootSDT)->PointerToOtherSDT[i];
            h = (SDTHeader*)(uint64_t)entry;
        }
        if (!h)
        {
            kinfoln("Entry points to null");
            continue;
        }
        kinfoln("Physical address of entry: %lx", (uint64_t)h);
        SDTHeader* realHeader = (SDTHeader*)KernelMemoryManager::get_unaligned_mapping(h);
        kinfoln("Mapped entry to virtual address %lx", (uint64_t)realHeader);
        if (!ValidateSDTHeader(realHeader))
        {
            kinfoln("Header is not valid, skipping this entry");
            KernelMemoryManager::release_unaligned_mapping(realHeader);
            continue;
        }
        char tableSignature[5];
        memcpy(tableSignature, h->Signature, 4);
        tableSignature[4] = 0;
        kinfoln("Comparing target signature (%s) to signature of entry (%s)", signature, tableSignature);
        if (strncmp(h->Signature, signature, 4) == 0)
        {
            kinfoln("Found table %s", signature);
            return (void*)realHeader;
        }
        kinfoln("Signatures do not match, unmapping entry and continuing");
        KernelMemoryManager::release_unaligned_mapping(realHeader);
    }

    return NULL;
}