/*
 * Copyright (c) 2026, Chloe M.
 * Provided under the BSD-3 clause.
 *
 * Description: Local APIC driver
 * Author:      Chloe M.
 */

#include <machine/lapic.h>
#include <machine/lapicreg.h>
#include <machine/msr.h>
#include <machine/cpuid.h>
#include <ex/trace.h>
#include <ke/knot.h>
#include <stdef.h>

/*
 * Trace only on the bootstrap processor but not on any others
 * to avoid log spam...
 */
#define DTRACE_BSP(Fmt, ...) do {                       \
        ULONG ApicBase;                                 \
                                                        \
        ApicBase = MdRdmsr(IA32_APIC_BASE_MSR);         \
        if (ISSET(ApicBase, BIT(8))) {                  \
            TRACE("[ LAPIC ]: " Fmt, ##__VA_ARGS__);    \
        }                                               \
    } while (0);

/*
 * Returns true if the Local APIC unit is supported on the
 * current processor.
 */
static BOOLEAN
LapicIsSupported(VOID)
{
    ULONG Edx, Unused;

    CPUID(1, Unused, Unused, Unused, Edx);
    return ISSET(Edx, BIT(9)) != 0;
}

/*
 * Enable the Local APIC unit
 */
static VOID
LapicEnable(VOID)
{
    UQUAD ApicBase;

    /* Hardware enable the Local APIC unit */
    ApicBase = MdRdmsr(IA32_APIC_BASE_MSR);
    ApicBase |= LAPIC_HW_ENABLE;
    MdWrmsr(IA32_APIC_BASE_MSR, ApicBase);
}

VOID
MdLapicInit(KPCR *Kpcr)
{
    if (Kpcr == NULL) {
        KeKnot(KNOT_MISC, "failed to initialize lapic driver\n");
    }

    if (!LapicIsSupported()) {
        KeKnot(KNOT_MISSING_HARDWARE, "local apic not supported\n");
    }

    LapicEnable();
}