xref: /freebsd-11-stable/sys/x86/acpica/acpi_apm.c

/*-
 * Copyright (c) 2001 Mitsuru IWASAKI
 * 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.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: head/sys/i386/acpica/acpi_machdep.c 205332 2010-03-19 12:43:18Z jhb $");

#include <sys/param.h>
#include <sys/bus.h>
#include <sys/condvar.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/poll.h>
#include <sys/sysctl.h>
#include <sys/uio.h>
#include <vm/vm.h>
#include <vm/pmap.h>

#include <contrib/dev/acpica/include/acpi.h>
#include <contrib/dev/acpica/include/accommon.h>
#include <contrib/dev/acpica/include/actables.h>

#include <dev/acpica/acpivar.h>
#include <dev/acpica/acpiio.h>

#include <machine/nexusvar.h>

/*
 * APM driver emulation
 */

#include <machine/apm_bios.h>
#include <machine/pc/bios.h>

#include <i386/bios/apm.h>

SYSCTL_DECL(_debug_acpi);

uint32_t acpi_resume_beep;
TUNABLE_INT("debug.acpi.resume_beep", &acpi_resume_beep);
SYSCTL_UINT(_debug_acpi, OID_AUTO, resume_beep, CTLFLAG_RW, &acpi_resume_beep,
    0, "Beep the PC speaker when resuming");
uint32_t acpi_reset_video;
TUNABLE_INT("hw.acpi.reset_video", &acpi_reset_video);

static int intr_model = ACPI_INTR_PIC;
static int apm_active;
static struct clonedevs *apm_clones;

MALLOC_DEFINE(M_APMDEV, "apmdev", "APM device emulation");

static d_open_t		apmopen;
static d_close_t	apmclose;
static d_write_t	apmwrite;
static d_ioctl_t	apmioctl;
static d_poll_t		apmpoll;
static d_kqfilter_t	apmkqfilter;
static void		apmreadfiltdetach(struct knote *kn);
static int		apmreadfilt(struct knote *kn, long hint);
static struct filterops	apm_readfiltops = {
	.f_isfd = 1,
	.f_detach = apmreadfiltdetach,
	.f_event = apmreadfilt,
};

static struct cdevsw apm_cdevsw = {
	.d_version =	D_VERSION,
	.d_flags =	D_TRACKCLOSE | D_NEEDMINOR,
	.d_open =	apmopen,
	.d_close =	apmclose,
	.d_write =	apmwrite,
	.d_ioctl =	apmioctl,
	.d_poll =	apmpoll,
	.d_name =	"apm",
	.d_kqfilter =	apmkqfilter
};

static int
acpi_capm_convert_battstate(struct  acpi_battinfo *battp)
{
	int	state;

	state = APM_UNKNOWN;

	if (battp->state & ACPI_BATT_STAT_DISCHARG) {
		if (battp->cap >= 50)
			state = 0;	/* high */
		else
			state = 1;	/* low */
	}
	if (battp->state & ACPI_BATT_STAT_CRITICAL)
		state = 2;		/* critical */
	if (battp->state & ACPI_BATT_STAT_CHARGING)
		state = 3;		/* charging */

	/* If still unknown, determine it based on the battery capacity. */
	if (state == APM_UNKNOWN) {
		if (battp->cap >= 50)
			state = 0;	/* high */
		else
			state = 1;	/* low */
	}

	return (state);
}

static int
acpi_capm_convert_battflags(struct  acpi_battinfo *battp)
{
	int	flags;

	flags = 0;

	if (battp->cap >= 50)
		flags |= APM_BATT_HIGH;
	else {
		if (battp->state & ACPI_BATT_STAT_CRITICAL)
			flags |= APM_BATT_CRITICAL;
		else
			flags |= APM_BATT_LOW;
	}
	if (battp->state & ACPI_BATT_STAT_CHARGING)
		flags |= APM_BATT_CHARGING;
	if (battp->state == ACPI_BATT_STAT_NOT_PRESENT)
		flags = APM_BATT_NOT_PRESENT;

	return (flags);
}

static int
acpi_capm_get_info(apm_info_t aip)
{
	int	acline;
	struct	acpi_battinfo batt;

	aip->ai_infoversion = 1;
	aip->ai_major       = 1;
	aip->ai_minor       = 2;
	aip->ai_status      = apm_active;
	aip->ai_capabilities= 0xff00;	/* unknown */

	if (acpi_acad_get_acline(&acline))
		aip->ai_acline = APM_UNKNOWN;	/* unknown */
	else
		aip->ai_acline = acline;	/* on/off */

	if (acpi_battery_get_battinfo(NULL, &batt) != 0) {
		aip->ai_batt_stat = APM_UNKNOWN;
		aip->ai_batt_life = APM_UNKNOWN;
		aip->ai_batt_time = -1;		 /* unknown */
		aip->ai_batteries = ~0U;	 /* unknown */
	} else {
		aip->ai_batt_stat = acpi_capm_convert_battstate(&batt);
		aip->ai_batt_life = batt.cap;
		aip->ai_batt_time = (batt.min == -1) ? -1 : batt.min * 60;
		aip->ai_batteries = acpi_battery_get_units();
	}

	return (0);
}

static int
acpi_capm_get_pwstatus(apm_pwstatus_t app)
{
	device_t dev;
	int	acline, unit, error;
	struct	acpi_battinfo batt;

	if (app->ap_device != PMDV_ALLDEV &&
	    (app->ap_device < PMDV_BATT0 || app->ap_device > PMDV_BATT_ALL))
		return (1);

	if (app->ap_device == PMDV_ALLDEV)
		error = acpi_battery_get_battinfo(NULL, &batt);
	else {
		unit = app->ap_device - PMDV_BATT0;
		dev = devclass_get_device(devclass_find("battery"), unit);
		if (dev != NULL)
			error = acpi_battery_get_battinfo(dev, &batt);
		else
			error = ENXIO;
	}
	if (error)
		return (1);

	app->ap_batt_stat = acpi_capm_convert_battstate(&batt);
	app->ap_batt_flag = acpi_capm_convert_battflags(&batt);
	app->ap_batt_life = batt.cap;
	app->ap_batt_time = (batt.min == -1) ? -1 : batt.min * 60;

	if (acpi_acad_get_acline(&acline))
		app->ap_acline = APM_UNKNOWN;
	else
		app->ap_acline = acline;	/* on/off */

	return (0);
}

/* Create single-use devices for /dev/apm and /dev/apmctl. */
static void
apm_clone(void *arg, struct ucred *cred, char *name, int namelen,
    struct cdev **dev)
{
	int ctl_dev, unit;

	if (*dev != NULL)
		return;
	if (strcmp(name, "apmctl") == 0)
		ctl_dev = TRUE;
	else if (strcmp(name, "apm") == 0)
		ctl_dev = FALSE;
	else
		return;

	/* Always create a new device and unit number. */
	unit = -1;
	if (clone_create(&apm_clones, &apm_cdevsw, &unit, dev, 0)) {
		if (ctl_dev) {
			*dev = make_dev(&apm_cdevsw, unit,
			    UID_ROOT, GID_OPERATOR, 0660, "apmctl%d", unit);
		} else {
			*dev = make_dev(&apm_cdevsw, unit,
			    UID_ROOT, GID_OPERATOR, 0664, "apm%d", unit);
		}
		if (*dev != NULL) {
			dev_ref(*dev);
			(*dev)->si_flags |= SI_CHEAPCLONE;
		}
	}
}

/* Create a struct for tracking per-device suspend notification. */
static struct apm_clone_data *
apm_create_clone(struct cdev *dev, struct acpi_softc *acpi_sc)
{
	struct apm_clone_data *clone;

	clone = malloc(sizeof(*clone), M_APMDEV, M_WAITOK);
	clone->cdev = dev;
	clone->acpi_sc = acpi_sc;
	clone->notify_status = APM_EV_NONE;
	bzero(&clone->sel_read, sizeof(clone->sel_read));
	knlist_init_mtx(&clone->sel_read.si_note, &acpi_mutex);

	/*
	 * The acpi device is always managed by devd(8) and is considered
	 * writable (i.e., ack is required to allow suspend to proceed.)
	 */
	if (strcmp("acpi", devtoname(dev)) == 0)
		clone->flags = ACPI_EVF_DEVD | ACPI_EVF_WRITE;
	else
		clone->flags = ACPI_EVF_NONE;

	ACPI_LOCK(acpi);
	STAILQ_INSERT_TAIL(&acpi_sc->apm_cdevs, clone, entries);
	ACPI_UNLOCK(acpi);
	return (clone);
}

static int
apmopen(struct cdev *dev, int flag, int fmt, struct thread *td)
{
	struct	acpi_softc *acpi_sc;
	struct 	apm_clone_data *clone;

	acpi_sc = devclass_get_softc(devclass_find("acpi"), 0);
	clone = apm_create_clone(dev, acpi_sc);
	dev->si_drv1 = clone;

	/* If the device is opened for write, record that. */
	if ((flag & FWRITE) != 0)
		clone->flags |= ACPI_EVF_WRITE;

	return (0);
}

static int
apmclose(struct cdev *dev, int flag, int fmt, struct thread *td)
{
	struct	apm_clone_data *clone;
	struct	acpi_softc *acpi_sc;

	clone = dev->si_drv1;
	acpi_sc = clone->acpi_sc;

	/* We are about to lose a reference so check if suspend should occur */
	if (acpi_sc->acpi_next_sstate != 0 &&
	    clone->notify_status != APM_EV_ACKED)
		acpi_AckSleepState(clone, 0);

	/* Remove this clone's data from the list and free it. */
	ACPI_LOCK(acpi);
	STAILQ_REMOVE(&acpi_sc->apm_cdevs, clone, apm_clone_data, entries);
	knlist_destroy(&clone->sel_read.si_note);
	ACPI_UNLOCK(acpi);
	free(clone, M_APMDEV);
	destroy_dev_sched(dev);
	return (0);
}

static int
apmioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flag, struct thread *td)
{
	int	error;
	struct	apm_clone_data *clone;
	struct	acpi_softc *acpi_sc;
	struct	apm_info info;
	struct 	apm_event_info *ev_info;
	apm_info_old_t aiop;

	error = 0;
	clone = dev->si_drv1;
	acpi_sc = clone->acpi_sc;

	switch (cmd) {
	case APMIO_SUSPEND:
		if ((flag & FWRITE) == 0)
			return (EPERM);
		if (acpi_sc->acpi_next_sstate == 0) {
			if (acpi_sc->acpi_suspend_sx != ACPI_STATE_S5) {
				error = acpi_ReqSleepState(acpi_sc,
				    acpi_sc->acpi_suspend_sx);
			} else {
				printf(
			"power off via apm suspend not supported\n");
				error = ENXIO;
			}
		} else
			error = acpi_AckSleepState(clone, 0);
		break;
	case APMIO_STANDBY:
		if ((flag & FWRITE) == 0)
			return (EPERM);
		if (acpi_sc->acpi_next_sstate == 0) {
			if (acpi_sc->acpi_standby_sx != ACPI_STATE_S5) {
				error = acpi_ReqSleepState(acpi_sc,
				    acpi_sc->acpi_standby_sx);
			} else {
				printf(
			"power off via apm standby not supported\n");
				error = ENXIO;
			}
		} else
			error = acpi_AckSleepState(clone, 0);
		break;
	case APMIO_NEXTEVENT:
		printf("apm nextevent start\n");
		ACPI_LOCK(acpi);
		if (acpi_sc->acpi_next_sstate != 0 && clone->notify_status ==
		    APM_EV_NONE) {
			ev_info = (struct apm_event_info *)addr;
			if (acpi_sc->acpi_next_sstate <= ACPI_STATE_S3)
				ev_info->type = PMEV_STANDBYREQ;
			else
				ev_info->type = PMEV_SUSPENDREQ;
			ev_info->index = 0;
			clone->notify_status = APM_EV_NOTIFIED;
			printf("apm event returning %d\n", ev_info->type);
		} else
			error = EAGAIN;
		ACPI_UNLOCK(acpi);
		break;
	case APMIO_GETINFO_OLD:
		if (acpi_capm_get_info(&info))
			error = ENXIO;
		aiop = (apm_info_old_t)addr;
		aiop->ai_major = info.ai_major;
		aiop->ai_minor = info.ai_minor;
		aiop->ai_acline = info.ai_acline;
		aiop->ai_batt_stat = info.ai_batt_stat;
		aiop->ai_batt_life = info.ai_batt_life;
		aiop->ai_status = info.ai_status;
		break;
	case APMIO_GETINFO:
		if (acpi_capm_get_info((apm_info_t)addr))
			error = ENXIO;
		break;
	case APMIO_GETPWSTATUS:
		if (acpi_capm_get_pwstatus((apm_pwstatus_t)addr))
			error = ENXIO;
		break;
	case APMIO_ENABLE:
		if ((flag & FWRITE) == 0)
			return (EPERM);
		apm_active = 1;
		break;
	case APMIO_DISABLE:
		if ((flag & FWRITE) == 0)
			return (EPERM);
		apm_active = 0;
		break;
	case APMIO_HALTCPU:
		break;
	case APMIO_NOTHALTCPU:
		break;
	case APMIO_DISPLAY:
		if ((flag & FWRITE) == 0)
			return (EPERM);
		break;
	case APMIO_BIOS:
		if ((flag & FWRITE) == 0)
			return (EPERM);
		bzero(addr, sizeof(struct apm_bios_arg));
		break;
	default:
		error = EINVAL;
		break;
	}

	return (error);
}

static int
apmwrite(struct cdev *dev, struct uio *uio, int ioflag)
{
	return (uio->uio_resid);
}

static int
apmpoll(struct cdev *dev, int events, struct thread *td)
{
	struct	apm_clone_data *clone;
	int revents;

	revents = 0;
	ACPI_LOCK(acpi);
	clone = dev->si_drv1;
	if (clone->acpi_sc->acpi_next_sstate)
		revents |= events & (POLLIN | POLLRDNORM);
	else
		selrecord(td, &clone->sel_read);
	ACPI_UNLOCK(acpi);
	return (revents);
}

static int
apmkqfilter(struct cdev *dev, struct knote *kn)
{
	struct	apm_clone_data *clone;

	ACPI_LOCK(acpi);
	clone = dev->si_drv1;
	kn->kn_hook = clone;
	kn->kn_fop = &apm_readfiltops;
	knlist_add(&clone->sel_read.si_note, kn, 0);
	ACPI_UNLOCK(acpi);
	return (0);
}

static void
apmreadfiltdetach(struct knote *kn)
{
	struct	apm_clone_data *clone;

	ACPI_LOCK(acpi);
	clone = kn->kn_hook;
	knlist_remove(&clone->sel_read.si_note, kn, 0);
	ACPI_UNLOCK(acpi);
}

static int
apmreadfilt(struct knote *kn, long hint)
{
	struct	apm_clone_data *clone;
	int	sleeping;

	ACPI_LOCK(acpi);
	clone = kn->kn_hook;
	sleeping = clone->acpi_sc->acpi_next_sstate ? 1 : 0;
	ACPI_UNLOCK(acpi);
	return (sleeping);
}

int
acpi_machdep_init(device_t dev)
{
	struct	acpi_softc *acpi_sc;

	acpi_sc = devclass_get_softc(devclass_find("acpi"), 0);

	/* Create a clone for /dev/acpi also. */
	STAILQ_INIT(&acpi_sc->apm_cdevs);
	acpi_sc->acpi_clone = apm_create_clone(acpi_sc->acpi_dev_t, acpi_sc);
	clone_setup(&apm_clones);
	EVENTHANDLER_REGISTER(dev_clone, apm_clone, 0, 1000);
	acpi_install_wakeup_handler(acpi_sc);

	if (intr_model == ACPI_INTR_PIC)
		BUS_CONFIG_INTR(dev, AcpiGbl_FADT.SciInterrupt,
		    INTR_TRIGGER_LEVEL, INTR_POLARITY_LOW);
	else
		acpi_SetIntrModel(intr_model);

	SYSCTL_ADD_UINT(&acpi_sc->acpi_sysctl_ctx,
	    SYSCTL_CHILDREN(acpi_sc->acpi_sysctl_tree), OID_AUTO,
	    "reset_video", CTLFLAG_RW, &acpi_reset_video, 0,
	    "Call the VESA reset BIOS vector on the resume path");

	return (0);
}

void
acpi_SetDefaultIntrModel(int model)
{

	intr_model = model;
}

/* Check BIOS date.  If 1998 or older, disable ACPI. */
int
acpi_machdep_quirks(int *quirks)
{
	char *va;
	int year;

	/* BIOS address 0xffff5 contains the date in the format mm/dd/yy. */
	va = pmap_mapbios(0xffff0, 16);
	sscanf(va + 11, "%2d", &year);
	pmap_unmapbios((vm_offset_t)va, 16);

	/*
	 * Date must be >= 1/1/1999 or we don't trust ACPI.  Note that this
	 * check must be changed by my 114th birthday.
	 */
	if (year > 90 && year < 99)
		*quirks = ACPI_Q_BROKEN;

	return (0);
}

void
acpi_cpu_c1()
{
	__asm __volatile("sti; hlt");
}

/*
 * Support for mapping ACPI tables during early boot.  This abuses the
 * crashdump map because the kernel cannot allocate KVA in
 * pmap_mapbios() when this is used.  This makes the following
 * assumptions about how we use this KVA: pages 0 and 1 are used to
 * map in the header of each table found via the RSDT or XSDT and
 * pages 2 to n are used to map in the RSDT or XSDT.  This has to use
 * 2 pages for the table headers in case a header spans a page
 * boundary.
 *
 * XXX: We don't ensure the table fits in the available address space
 * in the crashdump map.
 */

/*
 * Map some memory using the crashdump map.  'offset' is an offset in
 * pages into the crashdump map to use for the start of the mapping.
 */
static void *
table_map(vm_paddr_t pa, int offset, vm_offset_t length)
{
	vm_offset_t va, off;
	void *data;

	off = pa & PAGE_MASK;
	length = roundup(length + off, PAGE_SIZE);
	pa = pa & PG_FRAME;
	va = (vm_offset_t)pmap_kenter_temporary(pa, offset) +
	    (offset * PAGE_SIZE);
	data = (void *)(va + off);
	length -= PAGE_SIZE;
	while (length > 0) {
		va += PAGE_SIZE;
		pa += PAGE_SIZE;
		length -= PAGE_SIZE;
		pmap_kenter(va, pa);
		invlpg(va);
	}
	return (data);
}

/* Unmap memory previously mapped with table_map(). */
static void
table_unmap(void *data, vm_offset_t length)
{
	vm_offset_t va, off;

	va = (vm_offset_t)data;
	off = va & PAGE_MASK;
	length = roundup(length + off, PAGE_SIZE);
	va &= ~PAGE_MASK;
	while (length > 0) {
		pmap_kremove(va);
		invlpg(va);
		va += PAGE_SIZE;
		length -= PAGE_SIZE;
	}
}

/*
 * Map a table at a given offset into the crashdump map.  It first
 * maps the header to determine the table length and then maps the
 * entire table.
 */
static void *
map_table(vm_paddr_t pa, int offset, const char *sig)
{
	ACPI_TABLE_HEADER *header;
	vm_offset_t length;
	void *table;

	header = table_map(pa, offset, sizeof(ACPI_TABLE_HEADER));
	if (strncmp(header->Signature, sig, ACPI_NAME_SIZE) != 0) {
		table_unmap(header, sizeof(ACPI_TABLE_HEADER));
		return (NULL);
	}
	length = header->Length;
	table_unmap(header, sizeof(ACPI_TABLE_HEADER));
	table = table_map(pa, offset, length);
	if (ACPI_FAILURE(AcpiTbChecksum(table, length))) {
		if (bootverbose)
			printf("ACPI: Failed checksum for table %s\n", sig);
#if (ACPI_CHECKSUM_ABORT)
		table_unmap(table, length);
		return (NULL);
#endif
	}
	return (table);
}

/*
 * See if a given ACPI table is the requested table.  Returns the
 * length of the able if it matches or zero on failure.
 */
static int
probe_table(vm_paddr_t address, const char *sig)
{
	ACPI_TABLE_HEADER *table;

	table = table_map(address, 0, sizeof(ACPI_TABLE_HEADER));
	if (table == NULL) {
		if (bootverbose)
			printf("ACPI: Failed to map table at 0x%jx\n",
			    (uintmax_t)address);
		return (0);
	}
	if (bootverbose)
		printf("Table '%.4s' at 0x%jx\n", table->Signature,
		    (uintmax_t)address);

	if (strncmp(table->Signature, sig, ACPI_NAME_SIZE) != 0) {
		table_unmap(table, sizeof(ACPI_TABLE_HEADER));
		return (0);
	}
	table_unmap(table, sizeof(ACPI_TABLE_HEADER));
	return (1);
}

/*
 * Try to map a table at a given physical address previously returned
 * by acpi_find_table().
 */
void *
acpi_map_table(vm_paddr_t pa, const char *sig)
{

	return (map_table(pa, 0, sig));
}

/* Unmap a table previously mapped via acpi_map_table(). */
void
acpi_unmap_table(void *table)
{
	ACPI_TABLE_HEADER *header;

	header = (ACPI_TABLE_HEADER *)table;
	table_unmap(table, header->Length);
}

/*
 * Return the physical address of the requested table or zero if one
 * is not found.
 */
vm_paddr_t
acpi_find_table(const char *sig)
{
	ACPI_PHYSICAL_ADDRESS rsdp_ptr;
	ACPI_TABLE_RSDP *rsdp;
	ACPI_TABLE_RSDT *rsdt;
	ACPI_TABLE_XSDT *xsdt;
	ACPI_TABLE_HEADER *table;
	vm_paddr_t addr;
	int i, count;

	if (resource_disabled("acpi", 0))
		return (0);

	/*
	 * Map in the RSDP.  Since ACPI uses AcpiOsMapMemory() which in turn
	 * calls pmap_mapbios() to find the RSDP, we assume that we can use
	 * pmap_mapbios() to map the RSDP.
	 */
	if ((rsdp_ptr = AcpiOsGetRootPointer()) == 0)
		return (0);
	rsdp = pmap_mapbios(rsdp_ptr, sizeof(ACPI_TABLE_RSDP));
	if (rsdp == NULL) {
		if (bootverbose)
			printf("ACPI: Failed to map RSDP\n");
		return (0);
	}

	/*
	 * For ACPI >= 2.0, use the XSDT if it is available.
	 * Otherwise, use the RSDT.  We map the XSDT or RSDT at page 2
	 * in the crashdump area.  Pages 0 and 1 are used to map in the
	 * headers of candidate ACPI tables.
	 */
	addr = 0;
	if (rsdp->Revision >= 2 && rsdp->XsdtPhysicalAddress != 0) {
		/*
		 * AcpiOsGetRootPointer only verifies the checksum for
		 * the version 1.0 portion of the RSDP.  Version 2.0 has
		 * an additional checksum that we verify first.
		 */
		if (AcpiTbChecksum((UINT8 *)rsdp, ACPI_RSDP_XCHECKSUM_LENGTH)) {
			if (bootverbose)
				printf("ACPI: RSDP failed extended checksum\n");
			return (0);
		}
		xsdt = map_table(rsdp->XsdtPhysicalAddress, 2, ACPI_SIG_XSDT);
		if (xsdt == NULL) {
			if (bootverbose)
				printf("ACPI: Failed to map XSDT\n");
			return (0);
		}
		count = (xsdt->Header.Length - sizeof(ACPI_TABLE_HEADER)) /
		    sizeof(UINT64);
		for (i = 0; i < count; i++)
			if (probe_table(xsdt->TableOffsetEntry[i], sig)) {
				addr = xsdt->TableOffsetEntry[i];
				break;
			}
		acpi_unmap_table(xsdt);
	} else {
		rsdt = map_table(rsdp->RsdtPhysicalAddress, 2, ACPI_SIG_RSDT);
		if (rsdt == NULL) {
			if (bootverbose)
				printf("ACPI: Failed to map RSDT\n");
			return (0);
		}
		count = (rsdt->Header.Length - sizeof(ACPI_TABLE_HEADER)) /
		    sizeof(UINT32);
		for (i = 0; i < count; i++)
			if (probe_table(rsdt->TableOffsetEntry[i], sig)) {
				addr = rsdt->TableOffsetEntry[i];
				break;
			}
		acpi_unmap_table(rsdt);
	}
	pmap_unmapbios((vm_offset_t)rsdp, sizeof(ACPI_TABLE_RSDP));
	if (addr == 0) {
		if (bootverbose)
			printf("ACPI: No %s table found\n", sig);
		return (0);
	}
	if (bootverbose)
		printf("%s: Found table at 0x%jx\n", sig, (uintmax_t)addr);

	/*
	 * Verify that we can map the full table and that its checksum is
	 * correct, etc.
	 */
	table = map_table(addr, 0, sig);
	if (table == NULL)
		return (0);
	acpi_unmap_table(table);

	return (addr);
}

/*
 * ACPI nexus(4) driver.
 */
static int
nexus_acpi_probe(device_t dev)
{
	int error;

	error = acpi_identify();
	if (error)
		return (error);

	return (BUS_PROBE_DEFAULT);
}

static int
nexus_acpi_attach(device_t dev)
{

	nexus_init_resources();
	bus_generic_probe(dev);
	if (BUS_ADD_CHILD(dev, 10, "acpi", 0) == NULL)
		panic("failed to add acpi0 device");

	return (bus_generic_attach(dev));
}

static device_method_t nexus_acpi_methods[] = {
	/* Device interface */
	DEVMETHOD(device_probe,		nexus_acpi_probe),
	DEVMETHOD(device_attach,	nexus_acpi_attach),

	{ 0, 0 }
};

DEFINE_CLASS_1(nexus, nexus_acpi_driver, nexus_acpi_methods, 1, nexus_driver);
static devclass_t nexus_devclass;

DRIVER_MODULE(nexus_acpi, root, nexus_acpi_driver, nexus_devclass, 0, 0);