Chloe M.
106 lines
2.3 KiB
C
106 lines
2.3 KiB
C
/*
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* Copyright (c) 2026, Chloe M.
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* Provided under the BSD-3 clause.
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*
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* Description: Local APIC driver
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* Author: Chloe M.
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*/
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#include <machine/lapic.h>
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#include <machine/lapicreg.h>
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#include <machine/msr.h>
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#include <machine/cpuid.h>
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#include <drivers/acpi/tables.h>
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#include <drivers/acpi/acpi.h>
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#include <mm/vmm.h>
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#include <ex/trace.h>
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#include <ke/knot.h>
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#include <stdef.h>
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/*
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* Trace only on the bootstrap processor but not on any others
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* to avoid log spam...
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*/
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#define DTRACE_BSP(Fmt, ...) do { \
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ULONG ApicBase; \
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\
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ApicBase = MdRdmsr(IA32_APIC_BASE_MSR); \
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if (ISSET(ApicBase, BIT(8))) { \
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TRACE("[ LAPIC ]: " Fmt, ##__VA_ARGS__); \
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} \
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} while (0);
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/*
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* Returns true if the Local APIC unit is supported on the
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* current processor.
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*/
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static BOOLEAN
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LapicIsSupported(VOID)
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{
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ULONG Edx, Unused;
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CPUID(1, Unused, Unused, Unused, Edx);
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return ISSET(Edx, BIT(9)) != 0;
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}
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/*
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* Returns true if the CPU can operate its Local APIC unit
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* in the newer x2APIC mode.
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*/
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static BOOLEAN
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LapicHasX2Apic(VOID)
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{
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ULONG Ecx, Unused;
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CPUID(1, Unused, Unused, Ecx, Unused);
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return ISSET(Ecx, BIT(21)) != 0;
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}
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/*
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* Enable the Local APIC unit
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*/
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static VOID
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LapicEnable(VOID)
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{
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UQUAD ApicBase;
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/* Hardware enable the Local APIC unit */
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ApicBase = MdRdmsr(IA32_APIC_BASE_MSR);
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ApicBase |= LAPIC_HW_ENABLE;
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MdWrmsr(IA32_APIC_BASE_MSR, ApicBase);
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}
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VOID
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MdLapicInit(KPCR *Kpcr)
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{
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ACPI_MADT *Madt;
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MCB *Mcb;
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if (Kpcr == NULL) {
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KeKnot(
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KNOT_MISC,
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"lapic: failed to initialize lapic driver\n"
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);
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}
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if (!LapicIsSupported()) {
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KeKnot(
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KNOT_MISSING_HARDWARE,
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"lapic: local apic not supported\n"
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);
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}
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/* Obtain the ACPI MADT table */
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Madt = AcpiQuery("APIC");
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if (Madt == NULL) {
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KeKnot(KNOT_MISC, "lapic: could not obtain MADT\n");
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}
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Mcb = &Kpcr->Mcb;
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Mcb->LapicBase = PMA_TO_VMA((UPTR)Madt->LapicAddr);
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Mcb->HasX2Apic = LapicHasX2Apic();
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/* Enable the Local APIC */
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LapicEnable();
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}
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