/* $OpenBSD: acpicpu_x86.c,v 1.2 2025/09/16 12:18:10 hshoexer Exp $ */
/*
 * Copyright (c) 2005 Marco Peereboom <marco@openbsd.org>
 * Copyright (c) 2015 Philip Guenther <guenther@openbsd.org>
 *
 * 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/kernel.h>         /* for tick */
#include <sys/signalvar.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <sys/device.h>
#include <sys/malloc.h>
#include <sys/queue.h>
#include <sys/atomic.h>

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

#include <dev/acpi/acpireg.h>
#include <dev/acpi/acpivar.h>
#include <dev/acpi/acpidev.h>
#include <dev/acpi/amltypes.h>
#include <dev/acpi/dsdt.h>

#include <sys/sensors.h>

int     acpicpu_match(struct device *, void *, void *);
void    acpicpu_attach(struct device *, struct device *, void *);
int     acpicpu_notify(struct aml_node *, int, void *);
void    acpicpu_setperf(int);
void    acpicpu_setperf_ppc_change(struct acpicpu_pss *, int);

#define ACPI_STATE_C0           0x00
#define ACPI_STATE_C1           0x01
#define ACPI_STATE_C2           0x02
#define ACPI_STATE_C3           0x03

#define ACPI_PDC_REVID          0x1
#define ACPI_PDC_SMP            0xa
#define ACPI_PDC_MSR            0x1

/* _PDC/_OSC Intel capabilities flags */
#define ACPI_PDC_P_FFH          0x0001
#define ACPI_PDC_C_C1_HALT      0x0002
#define ACPI_PDC_T_FFH          0x0004
#define ACPI_PDC_SMP_C1PT       0x0008
#define ACPI_PDC_SMP_C2C3       0x0010
#define ACPI_PDC_SMP_P_SWCOORD  0x0020
#define ACPI_PDC_SMP_C_SWCOORD  0x0040
#define ACPI_PDC_SMP_T_SWCOORD  0x0080
#define ACPI_PDC_C_C1_FFH       0x0100
#define ACPI_PDC_C_C2C3_FFH     0x0200
/* reserved                     0x0400 */
#define ACPI_PDC_P_HWCOORD      0x0800
#define ACPI_PDC_PPC_NOTIFY     0x1000

#define CST_METH_HALT           0
#define CST_METH_IO_HALT        1
#define CST_METH_MWAIT          2
#define CST_METH_GAS_IO         3

/* flags on Intel's FFH mwait method */
#define CST_FLAG_MWAIT_HW_COORD         0x1
#define CST_FLAG_MWAIT_BM_AVOIDANCE     0x2
#define CST_FLAG_FALLBACK               0x4000  /* fallback for broken _CST */
#define CST_FLAG_SKIP                   0x8000  /* state is worse choice */

#define FLAGS_MWAIT_ONLY        0x02
#define FLAGS_BMCHECK           0x04
#define FLAGS_NOTHROTTLE        0x08
#define FLAGS_NOPSS             0x10
#define FLAGS_NOPCT             0x20

#define CPU_THT_EN              (1L << 4)
#define CPU_MAXSTATE(sc)        (1L << (sc)->sc_duty_wid)
#define CPU_STATE(sc,pct)       ((pct * CPU_MAXSTATE(sc) / 100) << (sc)->sc_duty_off)
#define CPU_STATEMASK(sc)       ((CPU_MAXSTATE(sc) - 1) << (sc)->sc_duty_off)

#define ACPI_MAX_C2_LATENCY     100
#define ACPI_MAX_C3_LATENCY     1000

#define CSD_COORD_SW_ALL        0xFC
#define CSD_COORD_SW_ANY        0xFD
#define CSD_COORD_HW_ALL        0xFE

/* Make sure throttling bits are valid,a=addr,o=offset,w=width */
#define valid_throttle(o,w,a)   (a && w && (o+w)<=31 && (o>4 || (o+w)<=4))

struct acpi_cstate {
        SLIST_ENTRY(acpi_cstate) link;

        u_short         state;
        short           method;         /* CST_METH_* */
        u_short         flags;          /* CST_FLAG_* */
        u_short         latency;
        int             power;
        uint64_t        address;        /* or mwait hint */
};

unsigned long cst_stats[4] = { 0 };

struct acpicpu_softc {
        struct device           sc_dev;
        int                     sc_cpu;

        int                     sc_duty_wid;
        int                     sc_duty_off;
        uint32_t                sc_pblk_addr;
        int                     sc_pblk_len;
        int                     sc_flags;
        unsigned long           sc_prev_sleep;
        unsigned long           sc_last_itime;

        struct cpu_info         *sc_ci;
        SLIST_HEAD(,acpi_cstate) sc_cstates;

        bus_space_tag_t         sc_iot;
        bus_space_handle_t      sc_ioh;

        struct acpi_softc       *sc_acpi;
        struct aml_node         *sc_devnode;

        int                     sc_pss_len;     /* XXX */
        int                     sc_ppc;
        int                     sc_level;
        struct acpicpu_pss      *sc_pss;
        size_t                  sc_pssfulllen;

        struct acpicpu_pct      sc_pct;
        /* save compensation for pct access for lying bios' */
        uint32_t                sc_pct_stat_as;
        uint32_t                sc_pct_ctrl_as;
        uint32_t                sc_pct_stat_len;
        uint32_t                sc_pct_ctrl_len;
        /*
         * XXX: _PPC Change listener
         * PPC changes can occur when for example a machine is disconnected
         * from AC power and can no longer support the highest frequency or
         * voltage when driven from the battery.
         * Should probably be reimplemented as a list for now we assume only
         * one listener
         */
        void                    (*sc_notify)(struct acpicpu_pss *, int);
};

void    acpicpu_add_cstatepkg(struct aml_value *, void *);
void    acpicpu_add_cdeppkg(struct aml_value *, void *);
int     acpicpu_getppc(struct acpicpu_softc *);
int     acpicpu_getpct(struct acpicpu_softc *);
int     acpicpu_getpss(struct acpicpu_softc *);
int     acpicpu_getcst(struct acpicpu_softc *);
void    acpicpu_getcst_from_fadt(struct acpicpu_softc *);
void    acpicpu_print_one_cst(struct acpi_cstate *_cx);
void    acpicpu_print_cst(struct acpicpu_softc *_sc);
void    acpicpu_add_cstate(struct acpicpu_softc *_sc, int _state, int _method,
            int _flags, int _latency, int _power, uint64_t _address);
void    acpicpu_set_pdc(struct acpicpu_softc *);
void    acpicpu_idle(void);
void    acpicpu_suspend(void);

#if 0
void    acpicpu_set_throttle(struct acpicpu_softc *, int);
struct acpi_cstate *acpicpu_find_cstate(struct acpicpu_softc *, int);
#endif

const struct cfattach acpicpu_ca = {
        sizeof(struct acpicpu_softc), acpicpu_match, acpicpu_attach
};

struct cfdriver acpicpu_cd = {
        NULL, "acpicpu", DV_DULL, CD_COCOVM
};

const char *acpicpu_hids[] = {
        "ACPI0007",
        NULL
};

extern int setperf_prio;

#if 0
void
acpicpu_set_throttle(struct acpicpu_softc *sc, int level)
{
        uint32_t pbval;

        if (sc->sc_flags & FLAGS_NOTHROTTLE)
                return;

        /* Disable throttling control */
        pbval = inl(sc->sc_pblk_addr);
        outl(sc->sc_pblk_addr, pbval & ~CPU_THT_EN);
        if (level < 100) {
                pbval &= ~CPU_STATEMASK(sc);
                pbval |= CPU_STATE(sc, level);
                outl(sc->sc_pblk_addr, pbval & ~CPU_THT_EN);
                outl(sc->sc_pblk_addr, pbval | CPU_THT_EN);
        }
}

struct acpi_cstate *
acpicpu_find_cstate(struct acpicpu_softc *sc, int state)
{
        struct acpi_cstate      *cx;

        SLIST_FOREACH(cx, &sc->sc_cstates, link)
                if (cx->state == state)
                        return cx;
        return (NULL);
}
#endif


void
acpicpu_set_pdc(struct acpicpu_softc *sc)
{
        struct aml_value cmd, osc_cmd[4];
        struct aml_value res;
        uint32_t cap;
        uint32_t buf[3];

        /* 4077A616-290C-47BE-9EBD-D87058713953 */
        static uint8_t cpu_oscuuid[16] = { 0x16, 0xA6, 0x77, 0x40, 0x0C, 0x29,
                                           0xBE, 0x47, 0x9E, 0xBD, 0xD8, 0x70,
                                           0x58, 0x71, 0x39, 0x53 };
        cap = ACPI_PDC_C_C1_HALT | ACPI_PDC_P_FFH | ACPI_PDC_C_C1_FFH
            | ACPI_PDC_C_C2C3_FFH | ACPI_PDC_SMP_P_SWCOORD | ACPI_PDC_SMP_C2C3
            | ACPI_PDC_SMP_C1PT;

        if (aml_searchname(sc->sc_devnode, "_OSC")) {
                /* Query _OSC */
                memset(&osc_cmd, 0, sizeof(osc_cmd));
                osc_cmd[0].type = AML_OBJTYPE_BUFFER;
                osc_cmd[0].v_buffer = (uint8_t *)&cpu_oscuuid;
                osc_cmd[0].length = sizeof(cpu_oscuuid);

                osc_cmd[1].type = AML_OBJTYPE_INTEGER;
                osc_cmd[1].v_integer = 1;
                osc_cmd[1].length = 1;

                osc_cmd[2].type = AML_OBJTYPE_INTEGER;
                osc_cmd[2].v_integer = 2;
                osc_cmd[2].length = 1;

                buf[0] = 1;
                buf[1] = cap;
                osc_cmd[3].type = AML_OBJTYPE_BUFFER;
                osc_cmd[3].v_buffer = (int8_t *)&buf;
                osc_cmd[3].length = sizeof(buf);

                aml_evalname(sc->sc_acpi, sc->sc_devnode, "_OSC",
                    4, osc_cmd, &res);

                if (res.type != AML_OBJTYPE_BUFFER || res.length < 8) {
                        printf(": unable to query capabilities\n");
                        aml_freevalue(&res);
                        return;
                }

                /* Evaluate _OSC */
                memset(&osc_cmd, 0, sizeof(osc_cmd));
                osc_cmd[0].type = AML_OBJTYPE_BUFFER;
                osc_cmd[0].v_buffer = (uint8_t *)&cpu_oscuuid;
                osc_cmd[0].length = sizeof(cpu_oscuuid);

                osc_cmd[1].type = AML_OBJTYPE_INTEGER;
                osc_cmd[1].v_integer = 1;
                osc_cmd[1].length = 1;

                osc_cmd[2].type = AML_OBJTYPE_INTEGER;
                osc_cmd[2].v_integer = 2;
                osc_cmd[2].length = 1;

                buf[0] = 0;
                buf[1] = (*(uint32_t *)&res.v_buffer[4]) & cap;
                osc_cmd[3].type = AML_OBJTYPE_BUFFER;
                osc_cmd[3].v_buffer = (int8_t *)&buf;
                osc_cmd[3].length = sizeof(buf);

                aml_freevalue(&res);

                aml_evalname(sc->sc_acpi, sc->sc_devnode, "_OSC",
                    4, osc_cmd, NULL);
        } else {
                /* Evaluate _PDC */
                memset(&cmd, 0, sizeof(cmd));
                cmd.type = AML_OBJTYPE_BUFFER;
                cmd.v_buffer = (uint8_t *)&buf;
                cmd.length = sizeof(buf);

                buf[0] = ACPI_PDC_REVID;
                buf[1] = 1;
                buf[2] = cap;

                aml_evalname(sc->sc_acpi, sc->sc_devnode, "_PDC",
                    1, &cmd, NULL);
        }
}

/*
 * sanity check mwait hints against what cpuid told us
 * ...but because intel screwed up, just check whether cpuid says
 * the given state has _any_ substates.
 */
static int
check_mwait_hints(int state, int hints)
{
        int cstate;
        int num_substates;

        if (cpu_mwait_size == 0)
                return (0);
        cstate = ((hints >> 4) & 0xf) + 1;
        if (cstate == 16)
                cstate = 0;
        else if (cstate > 7) {
                /* out of range of test against CPUID; just trust'em */
                return (1);
        }
        num_substates = (cpu_mwait_states >> (4 * cstate)) & 0xf;
        if (num_substates == 0) {
                printf(": C%d bad (state %d has no substates)", state, cstate);
                return (0);
        }
        return (1);
}

void
acpicpu_add_cstate(struct acpicpu_softc *sc, int state, int method,
    int flags, int latency, int power, uint64_t address)
{
        struct acpi_cstate      *cx;

        dnprintf(10," C%d: latency:.%4x power:%.4x addr:%.16llx\n",
            state, latency, power, address);

        /* add a new state, or overwrite the fallback C1 state? */
        if (state != ACPI_STATE_C1 ||
            (cx = SLIST_FIRST(&sc->sc_cstates)) == NULL ||
            (cx->flags & CST_FLAG_FALLBACK) == 0) {
                cx = malloc(sizeof(*cx), M_DEVBUF, M_WAITOK);
                SLIST_INSERT_HEAD(&sc->sc_cstates, cx, link);
        }

        cx->state = state;
        cx->method = method;
        cx->flags = flags;
        cx->latency = latency;
        cx->power = power;
        cx->address = address;
}

/* Found a _CST object, add new cstate for each entry */
void
acpicpu_add_cstatepkg(struct aml_value *val, void *arg)
{
        struct acpicpu_softc    *sc = arg;
        uint64_t addr;
        struct acpi_grd *grd;
        int state, method, flags;

#if defined(ACPI_DEBUG) && !defined(SMALL_KERNEL)
        aml_showvalue(val);
#endif
        if (val->type != AML_OBJTYPE_PACKAGE || val->length != 4)
                return;

        /* range and sanity checks */
        state = val->v_package[1]->v_integer;
        if (state < 0 || state > 4)
                return;
        if (val->v_package[0]->type != AML_OBJTYPE_BUFFER) {
                printf(": C%d (unexpected ACPI object type %d)",
                    state, val->v_package[0]->type);
                return;
        }
        grd = (struct acpi_grd *)val->v_package[0]->v_buffer;
        if (val->v_package[0]->length != sizeof(*grd) + 2 ||
            grd->grd_descriptor != LR_GENREGISTER ||
            grd->grd_length != sizeof(grd->grd_gas) ||
            val->v_package[0]->v_buffer[sizeof(*grd)] != SRT_ENDTAG) {
                printf(": C%d (bogo buffer)", state);
                return;
        }

        flags = 0;
        switch (grd->grd_gas.address_space_id) {
        case GAS_FUNCTIONAL_FIXED:
                if (grd->grd_gas.register_bit_width == 0) {
                        method = CST_METH_HALT;
                        addr = 0;
                } else {
                        /*
                         * In theory we should only do this for
                         * vendor 1 == Intel but other values crop up,
                         * presumably due to the normal ACPI spec confusion.
                         */
                        switch (grd->grd_gas.register_bit_offset) {
                        case 0x1:
                                method = CST_METH_IO_HALT;
                                addr = grd->grd_gas.address;

                                /* i386 and amd64 I/O space is 16bits */
                                if (addr > 0xffff) {
                                        printf(": C%d (bogo I/O addr %llx)",
                                            state, addr);
                                        return;
                                }
                                break;
                        case 0x2:
                                addr = grd->grd_gas.address;
                                if (!check_mwait_hints(state, addr))
                                        return;
                                method = CST_METH_MWAIT;
                                flags = grd->grd_gas.access_size;
                                break;
                        default:
                                printf(": C%d (unknown FFH class %d)",
                                    state, grd->grd_gas.register_bit_offset);
                                return;
                        }
                }
                break;

        case GAS_SYSTEM_IOSPACE:
                addr = grd->grd_gas.address;
                if (grd->grd_gas.register_bit_width != 8 ||
                    grd->grd_gas.register_bit_offset != 0) {
                        printf(": C%d (unhandled %s spec: %d/%d)", state,
                            "I/O", grd->grd_gas.register_bit_width,
                            grd->grd_gas.register_bit_offset);
                        return;
                }
                method = CST_METH_GAS_IO;
                break;

        default:
                /* dump the GAS for analysis */
                {
                        int i;
                        printf(": C%d (unhandled GAS:", state);
                        for (i = 0; i < sizeof(grd->grd_gas); i++)
                                printf(" %#x", ((u_char *)&grd->grd_gas)[i]);
                        printf(")");

                }
                return;
        }

        acpicpu_add_cstate(sc, state, method, flags,
            val->v_package[2]->v_integer, val->v_package[3]->v_integer, addr);
}


/* Found a _CSD object, print the dependency  */
void
acpicpu_add_cdeppkg(struct aml_value *val, void *arg)
{
        int64_t num_proc, coord_type, domain, cindex;

        /*
         * errors: unexpected object type, bad length, mismatched length,
         * and bad CSD revision
         */
        if (val->type != AML_OBJTYPE_PACKAGE || val->length < 6 ||
            val->length != val->v_package[0]->v_integer ||
            val->v_package[1]->v_integer != 0) {
#if 1 || defined(ACPI_DEBUG) && !defined(SMALL_KERNEL)
                aml_showvalue(val);
#endif
                printf("bogus CSD\n");
                return;
        }

        /* coordinating 'among' one CPU is trivial, ignore */
        num_proc = val->v_package[4]->v_integer;
        if (num_proc == 1)
                return;

        /* we practically assume the hardware will coordinate, so ignore */
        coord_type = val->v_package[3]->v_integer;
        if (coord_type == CSD_COORD_HW_ALL)
                return;

        domain = val->v_package[2]->v_integer;
        cindex = val->v_package[5]->v_integer;
        printf(": CSD (c=%#llx d=%lld n=%lld i=%lli)",
            coord_type, domain, num_proc, cindex);
}

int
acpicpu_getcst(struct acpicpu_softc *sc)
{
        struct aml_value        res;
        struct acpi_cstate      *cx, *next_cx;
        int                     use_nonmwait;

        /* delete the existing list */
        while ((cx = SLIST_FIRST(&sc->sc_cstates)) != NULL) {
                SLIST_REMOVE_HEAD(&sc->sc_cstates, link);
                free(cx, M_DEVBUF, sizeof(*cx));
        }

        /* provide a fallback C1-via-halt in case _CST's C1 is bogus */
        acpicpu_add_cstate(sc, ACPI_STATE_C1, CST_METH_HALT,
            CST_FLAG_FALLBACK, 1, -1, 0);

        if (aml_evalname(sc->sc_acpi, sc->sc_devnode, "_CST", 0, NULL, &res))
                return (1);

        aml_foreachpkg(&res, 1, acpicpu_add_cstatepkg, sc);
        aml_freevalue(&res);

        /* only have fallback state?  then no _CST objects were understood */
        cx = SLIST_FIRST(&sc->sc_cstates);
        if (cx->flags & CST_FLAG_FALLBACK)
                return (1);

        /*
         * Skip states >= C2 if the CPU's LAPIC timer stops in deep
         * states (i.e., it doesn't have the 'ARAT' bit set).
         * Also keep track if all the states we'll use use mwait.
         */
        use_nonmwait = 0;
        while ((next_cx = SLIST_NEXT(cx, link)) != NULL) {
                if (cx->state > 1 &&
                    (sc->sc_ci->ci_feature_tpmflags & TPM_ARAT) == 0)
                        cx->flags |= CST_FLAG_SKIP;
                else if (cx->method != CST_METH_MWAIT)
                        use_nonmwait = 1;
                cx = next_cx;
        }
        if (use_nonmwait)
                sc->sc_flags &= ~FLAGS_MWAIT_ONLY;
        else
                sc->sc_flags |= FLAGS_MWAIT_ONLY;

        if (!aml_evalname(sc->sc_acpi, sc->sc_devnode, "_CSD", 0, NULL, &res)) {
                aml_foreachpkg(&res, 1, acpicpu_add_cdeppkg, sc);
                aml_freevalue(&res);
        }

        return (0);
}

/*
 * old-style fixed C-state info in the FADT.
 * Note that this has extra restrictions on values and flags.
 */
void
acpicpu_getcst_from_fadt(struct acpicpu_softc *sc)
{
        struct acpi_fadt        *fadt = sc->sc_acpi->sc_fadt;
        int flags;

        /* FADT has to set flag to do C2 and higher on MP */
        if ((fadt->flags & FADT_P_LVL2_UP) == 0 && ncpus > 1)
                return;

        /* skip these C2 and C3 states if the CPU doesn't have ARAT */
        flags = (sc->sc_ci->ci_feature_tpmflags & TPM_ARAT)
            ? 0 : CST_FLAG_SKIP;

        /* Some systems don't export a full PBLK; reduce functionality */
        if (sc->sc_pblk_len >= 5 && fadt->p_lvl2_lat <= ACPI_MAX_C2_LATENCY) {
                acpicpu_add_cstate(sc, ACPI_STATE_C2, CST_METH_GAS_IO, flags,
                    fadt->p_lvl2_lat, -1, sc->sc_pblk_addr + 4);
        }
        if (sc->sc_pblk_len >= 6 && fadt->p_lvl3_lat <= ACPI_MAX_C3_LATENCY)
                acpicpu_add_cstate(sc, ACPI_STATE_C3, CST_METH_GAS_IO, flags,
                    fadt->p_lvl3_lat, -1, sc->sc_pblk_addr + 5);
}


void
acpicpu_print_one_cst(struct acpi_cstate *cx)
{
        const char *meth = "";
        int show_addr = 0;

        switch (cx->method) {
        case CST_METH_IO_HALT:
                show_addr = 1;
                /* fallthrough */
        case CST_METH_HALT:
                meth = " halt";
                break;

        case CST_METH_MWAIT:
                meth = " mwait";
                show_addr = cx->address != 0;
                break;

        case CST_METH_GAS_IO:
                meth = " io";
                show_addr = 1;
                break;

        }

        printf(" %sC%d(", (cx->flags & CST_FLAG_SKIP ? "!" : ""), cx->state);
        if (cx->power != -1)
                printf("%d", cx->power);
        printf("@%d%s", cx->latency, meth);
        if (cx->flags & ~CST_FLAG_SKIP) {
                if (cx->flags & CST_FLAG_FALLBACK)
                        printf("!");
                else
                        printf(".%x", (cx->flags & ~CST_FLAG_SKIP));
        }
        if (show_addr)
                printf("@0x%llx", cx->address);
        printf(")");
}

void
acpicpu_print_cst(struct acpicpu_softc *sc)
{
        struct acpi_cstate      *cx;
        int i;

        if (!SLIST_EMPTY(&sc->sc_cstates)) {
                printf(":");

                i = 0;
                SLIST_FOREACH(cx, &sc->sc_cstates, link) {
                        if (i++)
                                printf(",");
                        acpicpu_print_one_cst(cx);
                }
        }
}


int
acpicpu_match(struct device *parent, void *match, void *aux)
{
        struct acpi_attach_args *aa = aux;
        struct cfdata           *cf = match;
        struct acpi_softc       *acpi = (struct acpi_softc *)parent;
        CPU_INFO_ITERATOR       cii;
        struct cpu_info         *ci;
        int64_t                 uid;

        if (acpi_matchhids(aa, acpicpu_hids, cf->cf_driver->cd_name) &&
            aa->aaa_node && aa->aaa_node->value &&
            aa->aaa_node->value->type == AML_OBJTYPE_DEVICE) {
                /*
                 * Record that we've seen a Device() CPU object,
                 * so we won't attach any Processor() nodes.
                 */
                acpi->sc_skip_processor = 1;

                /* Only match if we can find a CPU with the right ID */
                if (aml_evalinteger(acpi, aa->aaa_node, "_UID", 0,
                    NULL, &uid) == 0)
                        CPU_INFO_FOREACH(cii, ci)
                                if (ci->ci_acpi_proc_id == uid)
                                        return (1);

                return (0);
        }

        /* 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
acpicpu_attach(struct device *parent, struct device *self, void *aux)
{
        struct acpicpu_softc    *sc = (struct acpicpu_softc *)self;
        struct acpi_attach_args *aa = aux;
        struct aml_value        res;
        int64_t                 uid;
        int                     i;
        uint32_t                status = 0;
        CPU_INFO_ITERATOR       cii;
        struct cpu_info         *ci;

        sc->sc_acpi = (struct acpi_softc *)parent;
        sc->sc_devnode = aa->aaa_node;

        SLIST_INIT(&sc->sc_cstates);

        if (aml_evalinteger(sc->sc_acpi, sc->sc_devnode,
            "_UID", 0, NULL, &uid) == 0)
                sc->sc_cpu = uid;

        if (aml_evalnode(sc->sc_acpi, sc->sc_devnode, 0, NULL, &res) == 0) {
                if (res.type == AML_OBJTYPE_PROCESSOR) {
                        sc->sc_cpu = res.v_processor.proc_id;
                        sc->sc_pblk_addr = res.v_processor.proc_addr;
                        sc->sc_pblk_len = res.v_processor.proc_len;
                }
                aml_freevalue(&res);
        }
        sc->sc_duty_off = sc->sc_acpi->sc_fadt->duty_offset;
        sc->sc_duty_wid = sc->sc_acpi->sc_fadt->duty_width;

        /* link in the matching cpu_info */
        CPU_INFO_FOREACH(cii, ci)
                if (ci->ci_acpi_proc_id == sc->sc_cpu) {
                        ci->ci_acpicpudev = self;
                        sc->sc_ci = ci;
                        break;
                }
        if (ci == NULL) {
                printf(": no cpu matching ACPI ID %d\n", sc->sc_cpu);
                return;
        }

        sc->sc_prev_sleep = 1000000;

        acpicpu_set_pdc(sc);

        if (!valid_throttle(sc->sc_duty_off, sc->sc_duty_wid, sc->sc_pblk_addr))
                sc->sc_flags |= FLAGS_NOTHROTTLE;
#ifdef ACPI_DEBUG
        printf(": %s: ", sc->sc_devnode->name);
        printf("\n: hdr:%x pblk:%x,%x duty:%x,%x pstate:%x "
               "(%ld throttling states)\n", sc->sc_acpi->sc_fadt->hdr_revision,
                sc->sc_pblk_addr, sc->sc_pblk_len, sc->sc_duty_off,
                sc->sc_duty_wid, sc->sc_acpi->sc_fadt->pstate_cnt,
                CPU_MAXSTATE(sc));
#endif

        /* Get C-States from _CST or FADT */
        if (acpicpu_getcst(sc) || SLIST_EMPTY(&sc->sc_cstates))
                acpicpu_getcst_from_fadt(sc);
        else {
                /* Notify BIOS we use _CST objects */
                if (sc->sc_acpi->sc_fadt->cst_cnt) {
                        acpi_write_pmreg(sc->sc_acpi, ACPIREG_SMICMD, 0,
                            sc->sc_acpi->sc_fadt->cst_cnt);
                }
        }
        if (!SLIST_EMPTY(&sc->sc_cstates)) {
                extern uint32_t acpi_force_bm;

                cpu_idle_cycle_fcn = &acpicpu_idle;
                cpu_suspend_cycle_fcn = &acpicpu_suspend;

                /*
                 * C3 (and maybe C2?) needs BM_RLD to be set to
                 * wake the system
                 */
                if (SLIST_FIRST(&sc->sc_cstates)->state > 1 && acpi_force_bm == 0) {
                        uint16_t en = acpi_read_pmreg(sc->sc_acpi,
                            ACPIREG_PM1_CNT, 0);
                        if ((en & ACPI_PM1_BM_RLD) == 0) {
                                acpi_write_pmreg(sc->sc_acpi, ACPIREG_PM1_CNT,
                                    0, en | ACPI_PM1_BM_RLD);
                                acpi_force_bm = ACPI_PM1_BM_RLD;
                        }
                }
        }

        if (acpicpu_getpss(sc)) {
                sc->sc_flags |= FLAGS_NOPSS;
        } else {
#ifdef ACPI_DEBUG
                for (i = 0; i < sc->sc_pss_len; i++) {
                        dnprintf(20, "%d %d %d %d %d %d\n",
                            sc->sc_pss[i].pss_core_freq,
                            sc->sc_pss[i].pss_power,
                            sc->sc_pss[i].pss_trans_latency,
                            sc->sc_pss[i].pss_bus_latency,
                            sc->sc_pss[i].pss_ctrl,
                            sc->sc_pss[i].pss_status);
                }
                dnprintf(20, "\n");
#endif
                if (sc->sc_pss_len == 0) {
                        /* this should never happen */
                        printf("%s: invalid _PSS length\n", DEVNAME(sc));
                        sc->sc_flags |= FLAGS_NOPSS;
                }

                acpicpu_getppc(sc);
                if (acpicpu_getpct(sc))
                        sc->sc_flags |= FLAGS_NOPCT;
                else if (sc->sc_pss_len > 0) {
                        /* Notify BIOS we are handling p-states */
                        if (sc->sc_acpi->sc_fadt->pstate_cnt) {
                                acpi_write_pmreg(sc->sc_acpi, ACPIREG_SMICMD,
                                    0, sc->sc_acpi->sc_fadt->pstate_cnt);
                        }

                        aml_register_notify(sc->sc_devnode, NULL,
                            acpicpu_notify, sc, ACPIDEV_NOPOLL);

                        acpi_gasio(sc->sc_acpi, ACPI_IOREAD,
                            sc->sc_pct.pct_status.grd_gas.address_space_id,
                            sc->sc_pct.pct_status.grd_gas.address,
                            sc->sc_pct_stat_as, sc->sc_pct_stat_as, &status);
                        sc->sc_level = (100 / sc->sc_pss_len) *
                            (sc->sc_pss_len - status);
                        dnprintf(20, "%s: cpu index %d, percentage %d\n",
                            DEVNAME(sc), status, sc->sc_level);
                        if (setperf_prio < 30) {
                                cpu_setperf = acpicpu_setperf;
                                acpicpu_set_notify(acpicpu_setperf_ppc_change);
                                setperf_prio = 30;
                                acpi_hasprocfvs = 1;
                        }
                }
        }

        /*
         * Nicely enumerate what power management capabilities
         * ACPI CPU provides.
         */
        acpicpu_print_cst(sc);
        if (!(sc->sc_flags & (FLAGS_NOPSS | FLAGS_NOPCT)) ||
            !(sc->sc_flags & FLAGS_NOPSS)) {
                printf("%c ", SLIST_EMPTY(&sc->sc_cstates) ? ':' : ',');

                /*
                 * If acpicpu is itself providing the capability to transition
                 * states, enumerate them in the fashion that est and powernow
                 * would.
                 */
                if (!(sc->sc_flags & (FLAGS_NOPSS | FLAGS_NOPCT))) {
                        printf("FVS, ");
                        for (i = 0; i < sc->sc_pss_len - 1; i++)
                                printf("%d, ", sc->sc_pss[i].pss_core_freq);
                        printf("%d MHz", sc->sc_pss[i].pss_core_freq);
                } else
                        printf("PSS");
        }

        printf("\n");
}

int
acpicpu_getppc(struct acpicpu_softc *sc)
{
        struct aml_value        res;

        sc->sc_ppc = 0;

        if (aml_evalname(sc->sc_acpi, sc->sc_devnode, "_PPC", 0, NULL, &res)) {
                dnprintf(10, "%s: no _PPC\n", DEVNAME(sc));
                return (1);
        }

        sc->sc_ppc = aml_val2int(&res);
        dnprintf(10, "%s: _PPC: %d\n", DEVNAME(sc), sc->sc_ppc);
        aml_freevalue(&res);

        return (0);
}

int
acpicpu_getpct(struct acpicpu_softc *sc)
{
        struct aml_value        res;
        int                     rv = 1;

        if (aml_evalname(sc->sc_acpi, sc->sc_devnode, "_PCT", 0, NULL, &res)) {
                dnprintf(20, "%s: no _PCT\n", DEVNAME(sc));
                return (1);
        }

        if (res.length != 2) {
                dnprintf(20, "%s: %s: invalid _PCT length\n", DEVNAME(sc),
                    sc->sc_devnode->name);
                return (1);
        }

        memcpy(&sc->sc_pct.pct_ctrl, res.v_package[0]->v_buffer,
            sizeof sc->sc_pct.pct_ctrl);
        if (sc->sc_pct.pct_ctrl.grd_gas.address_space_id ==
            GAS_FUNCTIONAL_FIXED) {
                dnprintf(20, "CTRL GASIO is functional fixed hardware.\n");
                goto ffh;
        }

        memcpy(&sc->sc_pct.pct_status, res.v_package[1]->v_buffer,
            sizeof sc->sc_pct.pct_status);
        if (sc->sc_pct.pct_status.grd_gas.address_space_id ==
            GAS_FUNCTIONAL_FIXED) {
                dnprintf(20, "CTRL GASIO is functional fixed hardware.\n");
                goto ffh;
        }

        dnprintf(10, "_PCT(ctrl)  : %02x %04x %02x %02x %02x %02x %016llx\n",
            sc->sc_pct.pct_ctrl.grd_descriptor,
            sc->sc_pct.pct_ctrl.grd_length,
            sc->sc_pct.pct_ctrl.grd_gas.address_space_id,
            sc->sc_pct.pct_ctrl.grd_gas.register_bit_width,
            sc->sc_pct.pct_ctrl.grd_gas.register_bit_offset,
            sc->sc_pct.pct_ctrl.grd_gas.access_size,
            sc->sc_pct.pct_ctrl.grd_gas.address);

        dnprintf(10, "_PCT(status): %02x %04x %02x %02x %02x %02x %016llx\n",
            sc->sc_pct.pct_status.grd_descriptor,
            sc->sc_pct.pct_status.grd_length,
            sc->sc_pct.pct_status.grd_gas.address_space_id,
            sc->sc_pct.pct_status.grd_gas.register_bit_width,
            sc->sc_pct.pct_status.grd_gas.register_bit_offset,
            sc->sc_pct.pct_status.grd_gas.access_size,
            sc->sc_pct.pct_status.grd_gas.address);

        /* if not set assume single 32 bit access */
        sc->sc_pct_stat_as = sc->sc_pct.pct_status.grd_gas.register_bit_width
            / 8;
        if (sc->sc_pct_stat_as == 0)
                sc->sc_pct_stat_as = 4;
        sc->sc_pct_ctrl_as = sc->sc_pct.pct_ctrl.grd_gas.register_bit_width / 8;
        if (sc->sc_pct_ctrl_as == 0)
                sc->sc_pct_ctrl_as = 4;
        sc->sc_pct_stat_len = sc->sc_pct.pct_status.grd_gas.access_size;
        if (sc->sc_pct_stat_len == 0)
                sc->sc_pct_stat_len = sc->sc_pct_stat_as;
        sc->sc_pct_ctrl_len = sc->sc_pct.pct_ctrl.grd_gas.access_size;
        if (sc->sc_pct_ctrl_len == 0)
                sc->sc_pct_ctrl_len = sc->sc_pct_ctrl_as;

        rv = 0;
ffh:
        aml_freevalue(&res);
        return (rv);
}

int
acpicpu_getpss(struct acpicpu_softc *sc)
{
        struct aml_value        res;
        int                     i, c, cf;

        if (aml_evalname(sc->sc_acpi, sc->sc_devnode, "_PSS", 0, NULL, &res)) {
                dprintf("%s: no _PSS\n", DEVNAME(sc));
                return (1);
        }

        free(sc->sc_pss, M_DEVBUF, sc->sc_pssfulllen);

        sc->sc_pss = mallocarray(res.length, sizeof(*sc->sc_pss), M_DEVBUF,
            M_WAITOK | M_ZERO);
        sc->sc_pssfulllen = res.length * sizeof(*sc->sc_pss);

        c = 0;
        for (i = 0; i < res.length; i++) {
                cf = aml_val2int(res.v_package[i]->v_package[0]);

                /* This heuristic comes from FreeBSDs
                 * dev/acpica/acpi_perf.c to weed out invalid PSS entries.
                 */
                if (cf == sc->sc_pss[c].pss_core_freq) {
                        printf("%s: struck PSS entry, core frequency equals "
                            " last\n", sc->sc_dev.dv_xname);
                        continue;
                }

                if (cf == 0xFFFF || cf == 0x9999 || cf == 99999 || cf == 0) {
                        printf("%s: struck PSS entry, inappropriate core "
                            "frequency value\n", sc->sc_dev.dv_xname);
                        continue;
                }

                sc->sc_pss[c].pss_core_freq = cf;
                sc->sc_pss[c].pss_power = aml_val2int(
                    res.v_package[i]->v_package[1]);
                sc->sc_pss[c].pss_trans_latency = aml_val2int(
                    res.v_package[i]->v_package[2]);
                sc->sc_pss[c].pss_bus_latency = aml_val2int(
                    res.v_package[i]->v_package[3]);
                sc->sc_pss[c].pss_ctrl = aml_val2int(
                    res.v_package[i]->v_package[4]);
                sc->sc_pss[c].pss_status = aml_val2int(
                    res.v_package[i]->v_package[5]);
                c++;
        }
        sc->sc_pss_len = c;

        aml_freevalue(&res);

        return (0);
}

int
acpicpu_fetch_pss(struct acpicpu_pss **pss)
{
        struct acpicpu_softc    *sc;

        /*
         * XXX: According to the ACPI spec in an SMP system all processors
         * are supposed to support the same states. For now we pray
         * the bios ensures this...
         */

        sc = (struct acpicpu_softc *)cpu_info_primary.ci_acpicpudev;
        if (!sc)
                return 0;
        *pss = sc->sc_pss;

        return (sc->sc_pss_len);
}

int
acpicpu_notify(struct aml_node *node, int notify_type, void *arg)
{
        struct acpicpu_softc    *sc = arg;

        dnprintf(10, "acpicpu_notify: %.2x %s\n", notify_type,
            sc->sc_devnode->name);

        switch (notify_type) {
        case 0x80:      /* _PPC changed, retrieve new values */
                acpicpu_getppc(sc);
                acpicpu_getpss(sc);
                if (sc->sc_notify)
                        sc->sc_notify(sc->sc_pss, sc->sc_pss_len);
                break;

        case 0x81:      /* _CST changed, retrieve new values */
                acpicpu_getcst(sc);
                printf("%s: notify", DEVNAME(sc));
                acpicpu_print_cst(sc);
                printf("\n");
                break;

        default:
                printf("%s: unhandled cpu event %x\n", DEVNAME(sc),
                    notify_type);
                break;
        }

        return (0);
}

void
acpicpu_set_notify(void (*func)(struct acpicpu_pss *, int))
{
        struct acpicpu_softc    *sc;

        sc = (struct acpicpu_softc *)cpu_info_primary.ci_acpicpudev;
        if (sc != NULL)
                sc->sc_notify = func;
}

void
acpicpu_setperf_ppc_change(struct acpicpu_pss *pss, int npss)
{
        struct acpicpu_softc    *sc;

        sc = (struct acpicpu_softc *)cpu_info_primary.ci_acpicpudev;

        if (sc != NULL)
                cpu_setperf(sc->sc_level);
}

void
acpicpu_setperf(int level)
{
        struct acpicpu_softc    *sc;
        struct acpicpu_pss      *pss = NULL;
        int                     idx, len;
        uint32_t                status = 0;

        sc = (struct acpicpu_softc *)curcpu()->ci_acpicpudev;

        dnprintf(10, "%s: acpicpu setperf level %d\n",
            sc->sc_devnode->name, level);

        if (level < 0 || level > 100) {
                dnprintf(10, "%s: acpicpu setperf illegal percentage\n",
                    sc->sc_devnode->name);
                return;
        }

        /*
         * XXX this should be handled more gracefully and it needs to also do
         * the duty cycle method instead of pss exclusively
         */
        if (sc->sc_flags & FLAGS_NOPSS || sc->sc_flags & FLAGS_NOPCT) {
                dnprintf(10, "%s: acpicpu no _PSS or _PCT\n",
                    sc->sc_devnode->name);
                return;
        }

        if (sc->sc_ppc)
                len = sc->sc_ppc;
        else
                len = sc->sc_pss_len;
        idx = (len - 1) - (level / (100 / len));
        if (idx < 0)
                idx = 0;

        if (sc->sc_ppc)
                idx += sc->sc_pss_len - sc->sc_ppc;

        if (idx > sc->sc_pss_len)
                idx = sc->sc_pss_len - 1;

        dnprintf(10, "%s: acpicpu setperf index %d pss_len %d ppc %d\n",
            sc->sc_devnode->name, idx, sc->sc_pss_len, sc->sc_ppc);

        pss = &sc->sc_pss[idx];

#ifdef ACPI_DEBUG
        /* keep this for now since we will need this for debug in the field */
        printf("0 status: %x %llx %u %u ctrl: %x %llx %u %u\n",
            sc->sc_pct.pct_status.grd_gas.address_space_id,
            sc->sc_pct.pct_status.grd_gas.address,
            sc->sc_pct_stat_as, sc->sc_pct_stat_len,
            sc->sc_pct.pct_ctrl.grd_gas.address_space_id,
            sc->sc_pct.pct_ctrl.grd_gas.address,
            sc->sc_pct_ctrl_as, sc->sc_pct_ctrl_len);
#endif
        acpi_gasio(sc->sc_acpi, ACPI_IOREAD,
            sc->sc_pct.pct_status.grd_gas.address_space_id,
            sc->sc_pct.pct_status.grd_gas.address, sc->sc_pct_stat_as,
            sc->sc_pct_stat_len, &status);
        dnprintf(20, "1 status: %u <- %u\n", status, pss->pss_status);

        /* Are we already at the requested frequency? */
        if (status == pss->pss_status)
                return;

        acpi_gasio(sc->sc_acpi, ACPI_IOWRITE,
            sc->sc_pct.pct_ctrl.grd_gas.address_space_id,
            sc->sc_pct.pct_ctrl.grd_gas.address, sc->sc_pct_ctrl_as,
            sc->sc_pct_ctrl_len, &pss->pss_ctrl);
        dnprintf(20, "pss_ctrl: %x\n", pss->pss_ctrl);

        acpi_gasio(sc->sc_acpi, ACPI_IOREAD,
            sc->sc_pct.pct_status.grd_gas.address_space_id,
            sc->sc_pct.pct_status.grd_gas.address, sc->sc_pct_stat_as,
            sc->sc_pct_stat_as, &status);
        dnprintf(20, "2 status: %d\n", status);

        /* Did the transition succeed? */
        if (status == pss->pss_status) {
                cpuspeed = pss->pss_core_freq;
                sc->sc_level = level;
        } else
                printf("%s: acpicpu setperf failed to alter frequency\n",
                    sc->sc_devnode->name);
}

void
acpicpu_idle(void)
{
        struct cpu_info *ci = curcpu();
        struct acpicpu_softc *sc = (struct acpicpu_softc *)ci->ci_acpicpudev;
        struct acpi_cstate *best, *cx;
        unsigned long itime;

        if (sc == NULL) {
                __asm volatile("sti");
                panic("null acpicpu");
        }

        /* possibly update the MWAIT_ONLY flag in cpu_info */
        if (sc->sc_flags & FLAGS_MWAIT_ONLY) {
                if ((ci->ci_mwait & MWAIT_ONLY) == 0)
                        atomic_setbits_int(&ci->ci_mwait, MWAIT_ONLY);
        } else if (ci->ci_mwait & MWAIT_ONLY)
                atomic_clearbits_int(&ci->ci_mwait, MWAIT_ONLY);

        /*
         * Find the first state with a latency we'll accept, ignoring
         * states marked skippable
         */
        best = cx = SLIST_FIRST(&sc->sc_cstates);
        while ((cx->flags & CST_FLAG_SKIP) ||
            cx->latency * 3 > sc->sc_prev_sleep) {
                if ((cx = SLIST_NEXT(cx, link)) == NULL)
                        break;
                best = cx;
        }

        if (best->state >= 3 &&
            (best->flags & CST_FLAG_MWAIT_BM_AVOIDANCE) &&
            acpi_read_pmreg(acpi_softc, ACPIREG_PM1_STS, 0) & ACPI_PM1_BM_STS) {
                /* clear it and back off */
                acpi_write_pmreg(acpi_softc, ACPIREG_PM1_STS, 0,
                    ACPI_PM1_BM_STS);
                while ((cx = SLIST_NEXT(cx, link)) != NULL) {
                        if (cx->flags & CST_FLAG_SKIP)
                                continue;
                        if (cx->state < 3 ||
                            (cx->flags & CST_FLAG_MWAIT_BM_AVOIDANCE) == 0)
                                break;
                }
                best = cx;
        }


        atomic_inc_long(&cst_stats[best->state]);

        itime = tick / 2;
        switch (best->method) {
        default:
        case CST_METH_HALT:
                __asm volatile("sti; hlt");
                break;

        case CST_METH_IO_HALT:
                inb((u_short)best->address);
                __asm volatile("sti; hlt");
                break;

        case CST_METH_MWAIT:
                {
                struct timeval start, stop;
                unsigned int hints;

#ifdef __LP64__
                if ((read_rflags() & PSL_I) == 0)
                        panic("idle with interrupts blocked!");
#else
                if ((read_eflags() & PSL_I) == 0)
                        panic("idle with interrupts blocked!");
#endif

                /* something already queued? */
                if (!cpu_is_idle(ci))
                        return;

                /*
                 * About to idle; setting the MWAIT_IN_IDLE bit tells
                 * cpu_unidle() that it can't be a no-op and tells cpu_kick()
                 * that it doesn't need to use an IPI.  We also set the
                 * MWAIT_KEEP_IDLING bit: those routines clear it to stop
                 * the mwait.  Once they're set, we do a final check of the
                 * queue, in case another cpu called setrunqueue() and added
                 * something to the queue and called cpu_unidle() between
                 * the check in sched_idle() and here.
                 */
                hints = (unsigned)best->address;
                microuptime(&start);
                atomic_setbits_int(&ci->ci_mwait, MWAIT_IDLING);
                if (cpu_is_idle(ci)) {
                        /* intel errata AAI65: cflush before monitor */
                        if (ci->ci_cflushsz != 0 &&
                            strcmp(cpu_vendor, "GenuineIntel") == 0) {
                                membar_sync();
                                clflush((unsigned long)&ci->ci_mwait);
                                membar_sync();
                        }

                        monitor(&ci->ci_mwait, 0, 0);
                        if ((ci->ci_mwait & MWAIT_IDLING) == MWAIT_IDLING)
                                mwait(0, hints);
                }

                microuptime(&stop);
                timersub(&stop, &start, &stop);
                itime = stop.tv_sec * 1000000 + stop.tv_usec;

                /* done idling; let cpu_kick() know that an IPI is required */
                atomic_clearbits_int(&ci->ci_mwait, MWAIT_IDLING);
                break;
                }

        case CST_METH_GAS_IO:
                inb((u_short)best->address);
                /* something harmless to give system time to change state */
                acpi_read_pmreg(acpi_softc, ACPIREG_PM1_STS, 0);
                break;

        }

        sc->sc_last_itime = itime;
        itime >>= 1;
        sc->sc_prev_sleep = (sc->sc_prev_sleep + (sc->sc_prev_sleep >> 1)
            + itime) >> 1;
}

void
acpicpu_suspend(void)
{
        extern int cpu_suspended;
        struct cpu_info *ci = curcpu();
        struct acpicpu_softc *sc = (struct acpicpu_softc *)ci->ci_acpicpudev;
        struct acpi_cstate *best, *cx;

        if (sc == NULL) {
                __asm volatile("sti");
                panic("null acpicpu");
        }

        /*
         * Find the lowest usable state.
         */
        best = cx = SLIST_FIRST(&sc->sc_cstates);
        while ((cx->flags & CST_FLAG_SKIP)) {
                if ((cx = SLIST_NEXT(cx, link)) == NULL)
                        break;
                best = cx;
        }

        switch (best->method) {
        default:
        case CST_METH_HALT:
                __asm volatile("sti; hlt");
                break;

        case CST_METH_IO_HALT:
                inb((u_short)best->address);
                __asm volatile("sti; hlt");
                break;

        case CST_METH_MWAIT:
                {
                unsigned int hints;

                hints = (unsigned)best->address;
                /* intel errata AAI65: cflush before monitor */
                if (ci->ci_cflushsz != 0 &&
                    strcmp(cpu_vendor, "GenuineIntel") == 0) {
                        membar_sync();
                        clflush((unsigned long)&cpu_suspended);
                        membar_sync();
                }

                monitor(&cpu_suspended, 0, 0);
                if (cpu_suspended || !CPU_IS_PRIMARY(ci))
                        mwait(0, hints);

                break;
                }

        case CST_METH_GAS_IO:
                inb((u_short)best->address);
                /* something harmless to give system time to change state */
                acpi_read_pmreg(acpi_softc, ACPIREG_PM1_STS, 0);
                break;

        }
}