/* $OpenBSD: acpitimer.c,v 1.17 2023/02/04 19:19:37 cheloha 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
};

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);
}