/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2008 Poul-Henning Kamp
 * Copyright (c) 2010 Alexander Motin <mav@FreeBSD.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: releng/12.0/sys/x86/isa/atrtc.c 335632 2018-06-25 11:01:12Z kib $
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: releng/12.0/sys/x86/isa/atrtc.c 335632 2018-06-25 11:01:12Z kib $");

#include "opt_isa.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/clock.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/proc.h>
#include <sys/rman.h>
#include <sys/timeet.h>

#include <isa/rtc.h>
#ifdef DEV_ISA
#include <isa/isareg.h>
#include <isa/isavar.h>
#endif
#include <machine/intr_machdep.h>
#include "clock_if.h"
#include <contrib/dev/acpica/include/acpi.h>
#include <machine/md_var.h>

/*
 * atrtc_lock protects low-level access to individual hardware registers.
 * atrtc_time_lock protects the entire sequence of accessing multiple registers
 * to read or write the date and time.
 */
static struct mtx atrtc_lock;
MTX_SYSINIT(atrtc_lock_init, &atrtc_lock, "atrtc", MTX_SPIN);

/* Force RTC enabled/disabled. */
static int atrtc_enabled = -1;
TUNABLE_INT("hw.atrtc.enabled", &atrtc_enabled);

struct mtx atrtc_time_lock;
MTX_SYSINIT(atrtc_time_lock_init, &atrtc_time_lock, "atrtc_time", MTX_DEF);

int	atrtcclock_disable = 0;

static	int	rtc_reg = -1;
static	u_char	rtc_statusa = RTCSA_DIVIDER | RTCSA_NOPROF;
static	u_char	rtc_statusb = RTCSB_24HR;

/*
 * RTC support routines
 */

static inline u_char
rtcin_locked(int reg)
{

	if (rtc_reg != reg) {
		inb(0x84);
		outb(IO_RTC, reg);
		rtc_reg = reg;
		inb(0x84);
	}
	return (inb(IO_RTC + 1));
}

static inline void
rtcout_locked(int reg, u_char val)
{

	if (rtc_reg != reg) {
		inb(0x84);
		outb(IO_RTC, reg);
		rtc_reg = reg;
		inb(0x84);
	}
	outb(IO_RTC + 1, val);
	inb(0x84);
}

int
rtcin(int reg)
{
	u_char val;

	mtx_lock_spin(&atrtc_lock);
	val = rtcin_locked(reg);
	mtx_unlock_spin(&atrtc_lock);
	return (val);
}

void
writertc(int reg, u_char val)
{

	mtx_lock_spin(&atrtc_lock);
	rtcout_locked(reg, val);
	mtx_unlock_spin(&atrtc_lock);
}

static void
atrtc_start(void)
{

	mtx_lock_spin(&atrtc_lock);
	rtcout_locked(RTC_STATUSA, rtc_statusa);
	rtcout_locked(RTC_STATUSB, RTCSB_24HR);
	mtx_unlock_spin(&atrtc_lock);
}

static void
atrtc_rate(unsigned rate)
{

	rtc_statusa = RTCSA_DIVIDER | rate;
	writertc(RTC_STATUSA, rtc_statusa);
}

static void
atrtc_enable_intr(void)
{

	rtc_statusb |= RTCSB_PINTR;
	mtx_lock_spin(&atrtc_lock);
	rtcout_locked(RTC_STATUSB, rtc_statusb);
	rtcin_locked(RTC_INTR);
	mtx_unlock_spin(&atrtc_lock);
}

static void
atrtc_disable_intr(void)
{

	rtc_statusb &= ~RTCSB_PINTR;
	mtx_lock_spin(&atrtc_lock);
	rtcout_locked(RTC_STATUSB, rtc_statusb);
	rtcin_locked(RTC_INTR);
	mtx_unlock_spin(&atrtc_lock);
}

void
atrtc_restore(void)
{

	/* Restore all of the RTC's "status" (actually, control) registers. */
	mtx_lock_spin(&atrtc_lock);
	rtcin_locked(RTC_STATUSA);	/* dummy to get rtc_reg set */
	rtcout_locked(RTC_STATUSB, RTCSB_24HR);
	rtcout_locked(RTC_STATUSA, rtc_statusa);
	rtcout_locked(RTC_STATUSB, rtc_statusb);
	rtcin_locked(RTC_INTR);
	mtx_unlock_spin(&atrtc_lock);
}

/**********************************************************************
 * RTC driver for subr_rtc
 */

struct atrtc_softc {
	int port_rid, intr_rid;
	struct resource *port_res;
	struct resource *intr_res;
	void *intr_handler;
	struct eventtimer et;
};

static int
rtc_start(struct eventtimer *et, sbintime_t first, sbintime_t period)
{

	atrtc_rate(max(fls(period + (period >> 1)) - 17, 1));
	atrtc_enable_intr();
	return (0);
}

static int
rtc_stop(struct eventtimer *et)
{

	atrtc_disable_intr();
	return (0);
}

/*
 * This routine receives statistical clock interrupts from the RTC.
 * As explained above, these occur at 128 interrupts per second.
 * When profiling, we receive interrupts at a rate of 1024 Hz.
 *
 * This does not actually add as much overhead as it sounds, because
 * when the statistical clock is active, the hardclock driver no longer
 * needs to keep (inaccurate) statistics on its own.  This decouples
 * statistics gathering from scheduling interrupts.
 *
 * The RTC chip requires that we read status register C (RTC_INTR)
 * to acknowledge an interrupt, before it will generate the next one.
 * Under high interrupt load, rtcintr() can be indefinitely delayed and
 * the clock can tick immediately after the read from RTC_INTR.  In this
 * case, the mc146818A interrupt signal will not drop for long enough
 * to register with the 8259 PIC.  If an interrupt is missed, the stat
 * clock will halt, considerably degrading system performance.  This is
 * why we use 'while' rather than a more straightforward 'if' below.
 * Stat clock ticks can still be lost, causing minor loss of accuracy
 * in the statistics, but the stat clock will no longer stop.
 */
static int
rtc_intr(void *arg)
{
	struct atrtc_softc *sc = (struct atrtc_softc *)arg;
	int flag = 0;

	while (rtcin(RTC_INTR) & RTCIR_PERIOD) {
		flag = 1;
		if (sc->et.et_active)
			sc->et.et_event_cb(&sc->et, sc->et.et_arg);
	}
	return(flag ? FILTER_HANDLED : FILTER_STRAY);
}

/*
 * Attach to the ISA PnP descriptors for the timer and realtime clock.
 */
static struct isa_pnp_id atrtc_ids[] = {
	{ 0x000bd041 /* PNP0B00 */, "AT realtime clock" },
	{ 0 }
};

static bool
atrtc_acpi_disabled(void)
{
	uint16_t flags;

	if (!acpi_get_fadt_bootflags(&flags))
		return (false);
	return ((flags & ACPI_FADT_NO_CMOS_RTC) != 0);
		return (true);
}

static int
atrtc_probe(device_t dev)
{
	int result;

	if ((atrtc_enabled == -1 && atrtc_acpi_disabled()) ||
	    (atrtc_enabled == 0))
		return (ENXIO);

	result = ISA_PNP_PROBE(device_get_parent(dev), dev, atrtc_ids);
	/* ENOENT means no PnP-ID, device is hinted. */
	if (result == ENOENT) {
		device_set_desc(dev, "AT realtime clock");
		return (BUS_PROBE_LOW_PRIORITY);
	}
	return (result);
}

static int
atrtc_attach(device_t dev)
{
	struct atrtc_softc *sc;
	rman_res_t s;
	int i;

	sc = device_get_softc(dev);
	sc->port_res = bus_alloc_resource(dev, SYS_RES_IOPORT, &sc->port_rid,
	    IO_RTC, IO_RTC + 1, 2, RF_ACTIVE);
	if (sc->port_res == NULL)
		device_printf(dev, "Warning: Couldn't map I/O.\n");
	atrtc_start();
	clock_register(dev, 1000000);
	bzero(&sc->et, sizeof(struct eventtimer));
	if (!atrtcclock_disable &&
	    (resource_int_value(device_get_name(dev), device_get_unit(dev),
	     "clock", &i) != 0 || i != 0)) {
		sc->intr_rid = 0;
		while (bus_get_resource(dev, SYS_RES_IRQ, sc->intr_rid,
		    &s, NULL) == 0 && s != 8)
			sc->intr_rid++;
		sc->intr_res = bus_alloc_resource(dev, SYS_RES_IRQ,
		    &sc->intr_rid, 8, 8, 1, RF_ACTIVE);
		if (sc->intr_res == NULL) {
			device_printf(dev, "Can't map interrupt.\n");
			return (0);
		} else if ((bus_setup_intr(dev, sc->intr_res, INTR_TYPE_CLK,
		    rtc_intr, NULL, sc, &sc->intr_handler))) {
			device_printf(dev, "Can't setup interrupt.\n");
			return (0);
		} else { 
			/* Bind IRQ to BSP to avoid live migration. */
			bus_bind_intr(dev, sc->intr_res, 0);
		}
		sc->et.et_name = "RTC";
		sc->et.et_flags = ET_FLAGS_PERIODIC | ET_FLAGS_POW2DIV;
		sc->et.et_quality = 0;
		sc->et.et_frequency = 32768;
		sc->et.et_min_period = 0x00080000;
		sc->et.et_max_period = 0x80000000;
		sc->et.et_start = rtc_start;
		sc->et.et_stop = rtc_stop;
		sc->et.et_priv = dev;
		et_register(&sc->et);
	}
	return(0);
}

static int
atrtc_resume(device_t dev)
{

	atrtc_restore();
	return(0);
}

static int
atrtc_settime(device_t dev __unused, struct timespec *ts)
{
	struct bcd_clocktime bct;

	clock_ts_to_bcd(ts, &bct, false);
	clock_dbgprint_bcd(dev, CLOCK_DBG_WRITE, &bct);

	mtx_lock(&atrtc_time_lock);
	mtx_lock_spin(&atrtc_lock);

	/* Disable RTC updates and interrupts.  */
	rtcout_locked(RTC_STATUSB, RTCSB_HALT | RTCSB_24HR);

	/* Write all the time registers. */
	rtcout_locked(RTC_SEC,   bct.sec);
	rtcout_locked(RTC_MIN,   bct.min);
	rtcout_locked(RTC_HRS,   bct.hour);
	rtcout_locked(RTC_WDAY,  bct.dow + 1);
	rtcout_locked(RTC_DAY,   bct.day);
	rtcout_locked(RTC_MONTH, bct.mon);
	rtcout_locked(RTC_YEAR,  bct.year & 0xff);
#ifdef USE_RTC_CENTURY
	rtcout_locked(RTC_CENTURY, bct.year >> 8);
#endif

	/*
	 * Re-enable RTC updates and interrupts.
	 */
	rtcout_locked(RTC_STATUSB, rtc_statusb);
	rtcin_locked(RTC_INTR);

	mtx_unlock_spin(&atrtc_lock);
	mtx_unlock(&atrtc_time_lock);

	return (0);
}

static int
atrtc_gettime(device_t dev, struct timespec *ts)
{
	struct bcd_clocktime bct;

	/* Look if we have a RTC present and the time is valid */
	if (!(rtcin(RTC_STATUSD) & RTCSD_PWR)) {
		device_printf(dev, "WARNING: Battery failure indication\n");
		return (EINVAL);
	}

	/*
	 * wait for time update to complete
	 * If RTCSA_TUP is zero, we have at least 244us before next update.
	 * This is fast enough on most hardware, but a refinement would be
	 * to make sure that no more than 240us pass after we start reading,
	 * and try again if so.
	 */
	mtx_lock(&atrtc_time_lock);
	while (rtcin(RTC_STATUSA) & RTCSA_TUP)
		continue;
	mtx_lock_spin(&atrtc_lock);
	bct.sec  = rtcin_locked(RTC_SEC);
	bct.min  = rtcin_locked(RTC_MIN);
	bct.hour = rtcin_locked(RTC_HRS);
	bct.day  = rtcin_locked(RTC_DAY);
	bct.mon  = rtcin_locked(RTC_MONTH);
	bct.year = rtcin_locked(RTC_YEAR);
#ifdef USE_RTC_CENTURY
	bct.year |= rtcin_locked(RTC_CENTURY) << 8;
#endif
	mtx_unlock_spin(&atrtc_lock);
	mtx_unlock(&atrtc_time_lock);
	/* dow is unused in timespec conversion and we have no nsec info. */
	bct.dow  = 0;
	bct.nsec = 0;
	clock_dbgprint_bcd(dev, CLOCK_DBG_READ, &bct);
	return (clock_bcd_to_ts(&bct, ts, false));
}

static device_method_t atrtc_methods[] = {
	/* Device interface */
	DEVMETHOD(device_probe,		atrtc_probe),
	DEVMETHOD(device_attach,	atrtc_attach),
	DEVMETHOD(device_detach,	bus_generic_detach),
	DEVMETHOD(device_shutdown,	bus_generic_shutdown),
	DEVMETHOD(device_suspend,	bus_generic_suspend),
		/* XXX stop statclock? */
	DEVMETHOD(device_resume,	atrtc_resume),

	/* clock interface */
	DEVMETHOD(clock_gettime,	atrtc_gettime),
	DEVMETHOD(clock_settime,	atrtc_settime),

	{ 0, 0 }
};

static driver_t atrtc_driver = {
	"atrtc",
	atrtc_methods,
	sizeof(struct atrtc_softc),
};

static devclass_t atrtc_devclass;

DRIVER_MODULE(atrtc, isa, atrtc_driver, atrtc_devclass, 0, 0);
DRIVER_MODULE(atrtc, acpi, atrtc_driver, atrtc_devclass, 0, 0);
ISA_PNP_INFO(atrtc_ids);
