Chloe M.
122 lines
2.7 KiB
C
122 lines
2.7 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: HPET driver
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* Author: Chloe M.
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*/
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#include <machine/hpet.h>
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#include <machine/hpetreg.h>
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#include <drivers/acpi/tables.h>
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#include <drivers/acpi/acpi.h>
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#include <hal/mmio.h>
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#include <mm/vmm.h>
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#include <ke/knot.h>
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#include <ex/trace.h>
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#include <units.h>
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#define DTRACE(Fmt, ...) \
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TRACE("[ HPET ]: " Fmt, ##__VA_ARGS__)
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static VOID *MMIOBase = NULL;
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/*
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* Write a 64-bit value to an HPET register
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*
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* @Register: Register to write to
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* @Value: Value to write
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*/
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static VOID
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HpetWriteq(UCHAR Register, UQUAD Value)
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{
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VOID *RegBase;
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if (MMIOBase == NULL) {
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return;
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}
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RegBase = PTR_OFFSET(MMIOBase, Register);
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MMIOWrite64(RegBase, Value);
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}
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/*
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* Read a 64-bit value from an HPET register
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*
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* @Register: Register to read from
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*/
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static UQUAD
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HpetReadq(UCHAR Register)
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{
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VOID *RegBase;
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if (MMIOBase == NULL) {
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return 0;
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}
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RegBase = PTR_OFFSET(MMIOBase, Register);
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return MMIORead64(RegBase);
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}
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USIZE
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MdHpetTimeUsec(VOID)
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{
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UQUAD Period, Freq, Caps;
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UQUAD Counter;
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Caps = HpetReadq(HPET_GENERAL_CAP);
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Period = (Caps >> HPET_PERIOD_SHIFT) & HPET_PERIOD_MASK;
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Freq = FSEC_PER_SECOND / Period;
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Counter = HpetReadq(HPET_MAIN_COUNTER);
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return (Counter * USEC_PER_SECOND) / Freq;
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}
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VOID
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MdHpetInit(VOID)
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{
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ACPI_HPET *Hpet;
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UQUAD GeneralCap, GeneralConf;
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ULONG ClkPeriod;
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UCHAR RevId;
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const ACPI_GAS *Gas;
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Hpet = AcpiQuery("HPET");
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if (Hpet == NULL) {
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KeKnot(
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KNOT_UNBOUND_RSRC,
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"could not detect HPET on this platform\n"
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);
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}
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/* Some informational logging */
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DTRACE("detected hpet with pci vendor id : %x\n", Hpet->PciVendorId);
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DTRACE("counter size : %d\n", Hpet->CounterSize);
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DTRACE("minimum tick : %d\n", Hpet->MinimumTick);
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/* Obtain the MMIO base address */
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Gas = &Hpet->Gas;
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MMIOBase = PMA_TO_VMA(Gas->Address);
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GeneralCap = HpetReadq(HPET_GENERAL_CAP);
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ClkPeriod = (GeneralCap >> HPET_PERIOD_SHIFT) & HPET_PERIOD_MASK;
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RevId = GeneralCap & 0xFF;
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DTRACE("counter clk period : %d\n", ClkPeriod);
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/*
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* Verify that the clock period and the revision ID are not
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* garbage values.
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*/
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if (ClkPeriod > HPET_MAX_CLK_PERIOD)
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KeKnot(KNOT_MISC, "hpet: bad counter clk period\n");
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if (RevId == 0)
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KeKnot(KNOT_MISC, "hpet: bad revision id, must not be zero\n");
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HpetWriteq(HPET_MAIN_COUNTER, 0);
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/* Enable the counter */
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GeneralConf = HpetReadq(HPET_GENERAL_CONF);
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GeneralConf |= HPET_GCONF_EN;
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HpetWriteq(HPET_GENERAL_CONF, GeneralConf);
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}
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