/* $OpenBSD: acpitimer.c,v 1.18 2025/09/16 12:18:10 hshoexer Exp $ */
/*
 * Copyright (c) 2005 Thorsten Lockert <tholo@sigmasoft.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/device.h>
#include <sys/stdint.h>
#include <sys/timetc.h>

#include <machine/bus.h>
#include <machine/cpu.h>

#include <dev/acpi/acpireg.h>
#include <dev/acpi/acpivar.h>

struct acpitimer_softc {
        struct device           sc_dev;

        bus_space_tag_t         sc_iot;
        bus_space_handle_t      sc_ioh;
};

int acpitimermatch(struct device *, void *, void *);
void acpitimerattach(struct device *, struct device *, void *);
void acpitimer_delay(int);
u_int acpi_get_timecount(struct timecounter *tc);
uint32_t acpitimer_read(struct acpitimer_softc *);

static struct timecounter acpi_timecounter = {
        .tc_get_timecount = acpi_get_timecount,
        .tc_counter_mask = 0x00ffffff,          /* 24 bits */
        .tc_frequency = ACPI_FREQUENCY,
        .tc_name = 0,
        .tc_quality = 1000,
        .tc_priv = NULL,
        .tc_user = 0,
};

const struct cfattach acpitimer_ca = {
        sizeof(struct acpitimer_softc), acpitimermatch, acpitimerattach
};

struct cfdriver acpitimer_cd = {
        NULL, "acpitimer", DV_DULL, CD_COCOVM
};

int
acpitimermatch(struct device *parent, void *match, void *aux)
{
        struct acpi_attach_args *aa = aux;
        struct cfdata *cf = match;

        /* sanity */
        if (aa->aaa_name == NULL ||
            strcmp(aa->aaa_name, cf->cf_driver->cd_name) != 0 ||
            aa->aaa_table != NULL)
                return (0);

        return (1);
}

void
acpitimerattach(struct device *parent, struct device *self, void *aux)
{
        struct acpitimer_softc *sc = (struct acpitimer_softc *) self;
        struct acpi_softc *psc = (struct acpi_softc *) parent;
        int rc;

        if (psc->sc_fadt->hdr_revision >= 3 &&
            psc->sc_fadt->x_pm_tmr_blk.address != 0)
                rc = acpi_map_address(psc, &psc->sc_fadt->x_pm_tmr_blk, 0,
                    psc->sc_fadt->pm_tmr_len, &sc->sc_ioh, &sc->sc_iot);
        else
                rc = acpi_map_address(psc, NULL, psc->sc_fadt->pm_tmr_blk,
                    psc->sc_fadt->pm_tmr_len, &sc->sc_ioh, &sc->sc_iot);
        if (rc) {
                printf(": can't map i/o space\n");
                return;
        }

        printf(": %d Hz, %d bits\n", ACPI_FREQUENCY,
            psc->sc_fadt->flags & FADT_TMR_VAL_EXT ? 32 : 24);

        if (psc->sc_fadt->flags & FADT_TMR_VAL_EXT)
                acpi_timecounter.tc_counter_mask = 0xffffffffU;
        acpi_timecounter.tc_priv = sc;
        acpi_timecounter.tc_name = sc->sc_dev.dv_xname;
        tc_init(&acpi_timecounter);

        delay_init(acpitimer_delay, 1000);

#if defined(__amd64__)
        extern void cpu_recalibrate_tsc(struct timecounter *);
        cpu_recalibrate_tsc(&acpi_timecounter);
#endif
}

void
acpitimer_delay(int usecs)
{
        uint64_t count = 0, cycles;
        struct acpitimer_softc *sc = acpi_timecounter.tc_priv;
        uint32_t mask = acpi_timecounter.tc_counter_mask;
        uint32_t val1, val2;

        val2 = acpitimer_read(sc);
        cycles = usecs * acpi_timecounter.tc_frequency / 1000000;
        while (count < cycles) {
                CPU_BUSY_CYCLE();
                val1 = val2;
                val2 = acpitimer_read(sc);
                count += (val2 - val1) & mask;
        }
}

u_int
acpi_get_timecount(struct timecounter *tc)
{
        return acpitimer_read(tc->tc_priv);
}

uint32_t
acpitimer_read(struct acpitimer_softc *sc)
{
        uint32_t u1, u2, u3;

        u2 = bus_space_read_4(sc->sc_iot, sc->sc_ioh, 0);
        u3 = bus_space_read_4(sc->sc_iot, sc->sc_ioh, 0);
        do {
                u1 = u2;
                u2 = u3;
                u3 = bus_space_read_4(sc->sc_iot, sc->sc_ioh, 0);
        } while (u1 > u2 || u2 > u3);

        return (u2);
}