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MontaukOS/kernel/src/ACPI/AcpiSleep.cpp
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/*
* AcpiSleep.cpp
* ACPI S3 suspend-to-RAM implementation
* Copyright (c) 2026 Daniel Hammer
*/
#include "AcpiSleep.hpp"
#include <ACPI/FADT.hpp>
#include <ACPI/AML/AmlParser.hpp>
#include <ACPI/AML/AmlInterpreter.hpp>
#include <Io/IoPort.hpp>
#include <Terminal/Terminal.hpp>
#include <CppLib/Stream.hpp>
#include <Memory/HHDM.hpp>
#include <Memory/Paging.hpp>
#include <Hal/GDT.hpp>
#include <Hal/Apic/Apic.hpp>
#include <Hal/Apic/IoApic.hpp>
#include <Hal/Apic/Pic.hpp>
#include <Timekeeping/ApicTimer.hpp>
#include <Drivers/Graphics/IntelGPU.hpp>
#include <Drivers/PS2/PS2Controller.hpp>
#include <Graphics/Cursor.hpp>
#include <Libraries/Memory.hpp>
using namespace Kt;
// Assembly routines from S3Wake.asm
extern "C" int AcpiSaveAndSuspend(Hal::AcpiSleep::CpuState* stateArea);
extern "C" void AcpiResumeLongMode(Hal::AcpiSleep::CpuState* stateArea);
extern "C" void AcpiWakeEntry();
extern "C" void* g_wakeStatePtr;
// Real-mode trampoline from S3Trampoline.asm
extern "C" char S3TrampolineStart[];
extern "C" char S3Trampoline64[];
extern "C" char S3TrampolineData[];
extern "C" char S3TrampolineEnd[];
// Physical address where the trampoline is copied (must be < 1MB, page-aligned)
static constexpr uint32_t TRAMPOLINE_PHYS = 0x8000;
// GDT/TSS reload helpers
namespace Hal {
extern void BridgeLoadGDT();
extern void LoadTSS();
}
namespace Hal {
namespace AcpiSleep {
// ── State ───────────────────────────────────────────────────────
static bool g_s3Available = false;
static uint16_t g_s3SlpTypA = 0;
static uint16_t g_s3SlpTypB = 0;
static uint32_t g_pm1aEventBlock = 0;
static uint32_t g_pm1bEventBlock = 0;
static uint32_t g_pm1aControlBlock = 0;
static uint32_t g_pm1bControlBlock = 0;
static uint8_t g_pm1EventLength = 0;
static FACS* g_facs = nullptr;
// CPU state save area (aligned for fxsave)
static CpuState g_cpuState __attribute__((aligned(64)));
// ── Initialize ──────────────────────────────────────────────────
void Initialize(ACPI::CommonSDTHeader* xsdt) {
g_s3Available = false;
FADT::ParsedFADT fadt{};
if (!FADT::Parse(xsdt, fadt) || !fadt.Valid)
return;
// Check if FACS exists
if (fadt.FacsAddress == 0) {
KernelLogStream(INFO, "S3") << "No FACS - S3 unavailable";
return;
}
g_facs = (FACS*)Memory::HHDM(fadt.FacsAddress);
// Verify FACS signature
if (g_facs->Signature[0] != 'F' || g_facs->Signature[1] != 'A' ||
g_facs->Signature[2] != 'C' || g_facs->Signature[3] != 'S') {
KernelLogStream(ERROR, "S3") << "Invalid FACS signature";
g_facs = nullptr;
return;
}
// Store PM register addresses
g_pm1aEventBlock = fadt.PM1aEventBlock;
g_pm1bEventBlock = fadt.PM1bEventBlock;
g_pm1aControlBlock = fadt.PM1aControlBlock;
g_pm1bControlBlock = fadt.PM1bControlBlock;
g_pm1EventLength = fadt.PM1EventLength;
// Find \_S3_ via brute-force DSDT scan (same approach as \_S5_).
// This works on any DSDT regardless of complexity — does not
// require the AML interpreter or namespace to be loaded.
auto* dsdt = (void*)Memory::HHDM(fadt.DsdtAddress);
AML::SleepObject s3 = AML::FindSleepState(dsdt, 3);
if (s3.Valid) {
g_s3SlpTypA = s3.SLP_TYPa;
g_s3SlpTypB = s3.SLP_TYPb;
g_s3Available = true;
KernelLogStream(OK, "S3") << "S3 suspend available (SLP_TYPa="
<< base::hex << (uint64_t)g_s3SlpTypA
<< " SLP_TYPb=" << base::hex << (uint64_t)g_s3SlpTypB << ")";
KernelLogStream(INFO, "S3") << "Kernel PML4 phys = " << base::hex
<< (uint64_t)Memory::VMM::g_paging->PML4;
} else {
KernelLogStream(INFO, "S3") << "\\_S3_ not found in DSDT - S3 unavailable";
}
}
bool IsS3Available() {
return g_s3Available;
}
// ── Evaluate _PTS (Prepare To Sleep) ────────────────────────────
static void EvaluatePts(int sleepState) {
auto& interp = AML::GetInterpreter();
if (!interp.IsInitialized()) return;
int32_t node = interp.GetNamespace().FindNode("\\_PTS");
if (node < 0) return;
AML::Object arg{};
arg.Type = AML::ObjectType::Integer;
arg.Integer = (uint64_t)sleepState;
AML::Object result{};
interp.EvaluateMethod("\\_PTS", &arg, 1, result);
KernelLogStream(DEBUG, "S3") << "Evaluated \\_PTS(" << base::dec << (uint64_t)sleepState << ")";
}
// ── Evaluate _WAK (System Wake) ─────────────────────────────────
static void EvaluateWak(int sleepState) {
auto& interp = AML::GetInterpreter();
if (!interp.IsInitialized()) return;
int32_t node = interp.GetNamespace().FindNode("\\_WAK");
if (node < 0) return;
AML::Object arg{};
arg.Type = AML::ObjectType::Integer;
arg.Integer = (uint64_t)sleepState;
AML::Object result{};
interp.EvaluateMethod("\\_WAK", &arg, 1, result);
KernelLogStream(DEBUG, "S3") << "Evaluated \\_WAK(" << base::dec << (uint64_t)sleepState << ")";
}
// ── Clear PM1 Status Registers ──────────────────────────────────
static void ClearPM1Status() {
// Write 1 to clear all status bits (write-1-to-clear semantics)
uint16_t clearMask = PM1_WAK_STS | PM1_PWRBTN_STS | PM1_SLPBTN_STS |
PM1_RTC_STS | PM1_TMR_STS | PM1_BM_STS | PM1_GBL_STS;
if (g_pm1aEventBlock != 0)
Io::Out16(clearMask, (uint16_t)g_pm1aEventBlock);
if (g_pm1bEventBlock != 0)
Io::Out16(clearMask, (uint16_t)g_pm1bEventBlock);
}
// ── Enable Wake Events ──────────────────────────────────────────
static void EnableWakeEvents() {
// Enable register is at event block + PM1EventLength/2
uint16_t enableOffset = g_pm1EventLength / 2;
// Enable power button and RTC as wake sources
uint16_t enableMask = PM1_PWRBTN_EN | PM1_RTC_EN;
if (g_pm1aEventBlock != 0 && enableOffset > 0)
Io::Out16(enableMask, (uint16_t)(g_pm1aEventBlock + enableOffset));
if (g_pm1bEventBlock != 0 && enableOffset > 0)
Io::Out16(enableMask, (uint16_t)(g_pm1bEventBlock + enableOffset));
}
// ── Install real-mode trampoline and set waking vector ────────────
static void SetWakingVector() {
if (!g_facs) return;
// Store the CpuState pointer where the 64-bit wake stub can find it.
g_wakeStatePtr = (void*)&g_cpuState;
// Copy the real-mode trampoline to low physical memory (0x8000).
// This code transitions real mode → protected mode → long mode
// and then jumps to AcpiResumeLongMode in the kernel.
uint32_t trampolineSize = (uint32_t)(S3TrampolineEnd - S3TrampolineStart);
uint8_t* trampolineDst = (uint8_t*)Memory::HHDM((uint64_t)TRAMPOLINE_PHYS);
uint8_t* trampolineSrc = (uint8_t*)S3TrampolineStart;
memcpy(trampolineDst, trampolineSrc, trampolineSize);
// Patch the trampoline data area with CR3 and resume addresses.
// Data layout (from S3Trampoline.asm):
// +0: uint64_t CR3 (full 64-bit PML4 physical address)
// +8: uint64_t CpuState virtual address
// +16: uint64_t AcpiResumeLongMode virtual address
uint32_t dataOffset = (uint32_t)(S3TrampolineData - S3TrampolineStart);
uint8_t* dataArea = trampolineDst + dataOffset;
// Use the kernel master PML4 (which has 0x8000 identity-mapped)
// rather than the saved process PML4 (which doesn't).
// AcpiResumeLongMode will restore the saved CR3 after we're
// safely back in long mode with kernel GDT/IDT.
uint64_t cr3val = (uint64_t)Memory::VMM::g_paging->PML4;
// The 16-bit->32-bit trampoline path can only load 32-bit CR3.
// If the PML4 is above 4GB, the real-mode wake path would fail.
if (cr3val > 0xFFFFFFFF) {
KernelLogStream(ERROR, "S3") << "PML4 at " << base::hex << cr3val
<< " is above 4GB - real-mode wake path will fail!";
}
memcpy(dataArea + 0, &cr3val, 8);
uint64_t statePtr = (uint64_t)&g_cpuState;
memcpy(dataArea + 8, &statePtr, 8);
uint64_t resumeAddr = (uint64_t)&AcpiResumeLongMode;
memcpy(dataArea + 16, &resumeAddr, 8);
// Set the 32-bit waking vector only. Setting X_FirmwareWakingVector
// to non-zero causes this laptop's firmware to hang during wake.
g_facs->FirmwareWakingVector = TRAMPOLINE_PHYS;
g_facs->X_FirmwareWakingVector = 0;
KernelLogStream(DEBUG, "S3") << "Trampoline installed at " << base::hex
<< (uint64_t)TRAMPOLINE_PHYS << " (" << base::dec
<< (uint64_t)trampolineSize << " bytes)";
KernelLogStream(DEBUG, "S3") << "Trampoline CR3 = " << base::hex << cr3val;
}
// ── Wait for WAK_STS ────────────────────────────────────────────
static void WaitForWake() {
// After entering S3, the CPU halts. On resume, firmware runs the
// waking vector. But if we somehow didn't enter sleep (e.g. immediate
// wake), poll WAK_STS.
for (int i = 0; i < 10000; i++) {
if (g_pm1aEventBlock != 0) {
uint16_t sts = Io::In16((uint16_t)g_pm1aEventBlock);
if (sts & PM1_WAK_STS) return;
}
Io::IoPortWait();
}
}
// ── Suspend ─────────────────────────────────────────────────────
int Suspend() {
if (!g_s3Available) {
KernelLogStream(ERROR, "S3") << "S3 suspend not available";
return -1;
}
KernelLogStream(INFO, "S3") << "Preparing for S3 suspend...";
// 1. Evaluate _PTS(3) — Prepare To Sleep
EvaluatePts(3);
// 2. Save CPU state. AcpiSaveAndSuspend returns 1 on initial call,
// and 0 when we resume from S3 (AcpiResumeLongMode sets RAX=0).
int resumed = !AcpiSaveAndSuspend(&g_cpuState);
if (resumed) {
// ── RESUME PATH ─────────────────────────────────────────
// We just woke from S3. Firmware ran our waking vector which
// called AcpiResumeLongMode, restoring all registers and
// returning here with 0.
// Debug: write a green rectangle to the top-left corner of the
// framebuffer. The framebuffer memory survives S3 (it's RAM).
// This will be visible once the GPU display plane is restored,
// confirming the CPU successfully completed the resume path.
{
uint32_t* fb = ::Graphics::Cursor::GetFramebufferBase();
uint64_t pitch = ::Graphics::Cursor::GetFramebufferPitch();
if (fb && pitch > 0) {
for (int y = 0; y < 32; y++) {
uint32_t* row = (uint32_t*)((uint8_t*)fb + y * pitch);
for (int x = 0; x < 32; x++) {
row[x] = 0xFF00FF00; // Green (ARGB)
}
}
}
}
// Reload GDT and TSS (firmware may have clobbered them)
Hal::BridgeLoadGDT();
Hal::LoadTSS();
// Re-disable legacy 8259 PIC. Firmware may have re-enabled
// it during S3 resume POST, which could cause spurious
// interrupts on conflicting vectors once we enable interrupts.
Hal::DisableLegacyPic();
// Re-enable the Local APIC (MSR global enable + SVR + TPR)
Hal::LocalApic::Reinitialize();
// Restore I/O APIC redirection entries (lost during S3).
// Must be done before enabling interrupts so IRQ routing
// is in place when devices start generating interrupts.
Hal::IoApic::Reinitialize();
// Restart the APIC timer
Timekeeping::ApicTimerReinitialize();
// Clear WAK_STS
ClearPM1Status();
// Evaluate _WAK(3)
EvaluateWak(3);
// Re-enable PS/2 controller (ports and interrupts may be
// disabled after S3; skip full self-test to avoid resetting
// attached devices)
Drivers::PS2::Reinitialize();
// Restore Intel GPU display (GTT + display plane lost during S3)
if (Drivers::Graphics::IntelGPU::IsInitialized()) {
Drivers::Graphics::IntelGPU::Reinitialize();
}
// Re-enable interrupts
asm volatile("sti");
KernelLogStream(OK, "S3") << "Resumed from S3 suspend";
return 0;
}
// ── SUSPEND PATH (initial save returned 1) ──────────────────
// 3. Disable interrupts
asm volatile("cli");
// 4. Identity-map the trampoline page so the CPU can execute it
// after paging is re-enabled with our CR3 during wake.
// Physical 0x8000 → virtual 0x8000 (flat identity mapping).
Memory::VMM::g_paging->Map(TRAMPOLINE_PHYS, TRAMPOLINE_PHYS);
// 5. Flush all caches
asm volatile("wbinvd");
// 6. Set the waking vector in FACS
SetWakingVector();
// 7. Clear any pending PM1 status bits
ClearPM1Status();
// 8. Enable wake events (power button, RTC)
EnableWakeEvents();
// 9. Write SLP_TYP to PM1 control registers (without SLP_EN)
uint16_t pm1a = Io::In16((uint16_t)g_pm1aControlBlock);
pm1a = (pm1a & ~PM1_SLP_TYP_MASK) | (g_s3SlpTypA << 10);
Io::Out16(pm1a, (uint16_t)g_pm1aControlBlock);
if (g_pm1bControlBlock != 0) {
uint16_t pm1b = Io::In16((uint16_t)g_pm1bControlBlock);
pm1b = (pm1b & ~PM1_SLP_TYP_MASK) | (g_s3SlpTypB << 10);
Io::Out16(pm1b, (uint16_t)g_pm1bControlBlock);
}
// 10. Flush caches again
asm volatile("wbinvd");
// 11. Assert SLP_EN — this triggers S3 entry
Io::Out16(pm1a | PM1_SLP_EN, (uint16_t)g_pm1aControlBlock);
if (g_pm1bControlBlock != 0) {
uint16_t pm1b = Io::In16((uint16_t)g_pm1bControlBlock);
Io::Out16(pm1b | PM1_SLP_EN, (uint16_t)g_pm1bControlBlock);
}
// The CPU must halt for the chipset/hypervisor to complete the S3
// transition. On real hardware the chipset cuts power after SLP_EN;
// on QEMU/KVM the vCPU must reach HLT before QEMU finalizes S3.
// On resume, firmware jumps to our waking vector.
for (;;) {
asm volatile("hlt");
// If we wake from HLT (spurious or real wake), check WAK_STS
if (g_pm1aEventBlock != 0) {
uint16_t sts = Io::In16((uint16_t)g_pm1aEventBlock);
if (sts & PM1_WAK_STS) break;
}
}
// If we get here, either S3 failed or we woke immediately.
// The normal wake path goes through AcpiResumeLongMode instead.
// Re-enable interrupts as a safety measure.
asm volatile("sti");
KernelLogStream(WARNING, "S3") << "S3 entry may have failed (fell through)";
return 0;
}
};
};
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