lwkt_runnable is declared in <sys/thread2.h>

[dragonfly.git] / sys / dev / acpica5 / acpi_cpu.c

/*-
 * Copyright (c) 2003 Nate Lawson (SDG)
 * Copyright (c) 2001 Michael Smith
 * 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: src/sys/dev/acpica/acpi_cpu.c,v 1.41 2004/06/24 00:38:51 njl Exp $
 * $DragonFly: src/sys/dev/acpica5/acpi_cpu.c,v 1.8 2004/11/21 09:07:14 y0netan1 Exp $
 */

#include "opt_acpi.h"
#include <sys/param.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/globaldata.h>
#include <sys/power.h>
#include <sys/proc.h>
#include <sys/sbuf.h>
#include <sys/thread2.h>

#include <bus/pci/pcivar.h>
#include <machine/atomic.h>
#include <machine/bus.h>
#include <machine/globaldata.h>
#include <machine/smp.h>
#include <sys/rman.h>

#include "acpi.h"
#include "acpivar.h"

/*
 * Support for ACPI Processor devices, including ACPI 2.0 throttling
 * and C[1-3] sleep states.
 *
 * TODO: implement scans of all CPUs to be sure all Cx states are
 * equivalent.
 */

/* Hooks for the ACPI CA debugging infrastructure */
#define _COMPONENT      ACPI_PROCESSOR
ACPI_MODULE_NAME("PROCESSOR")

struct acpi_cx {
    struct resource     *p_lvlx;        /* Register to read to enter state. */
    uint32_t             type;          /* C1-3 (C4 and up treated as C3). */
    uint32_t             trans_lat;     /* Transition latency (usec). */
    uint32_t             power;         /* Power consumed (mW). */
};
#define MAX_CX_STATES    8

struct acpi_cpu_softc {
    device_t             cpu_dev;
    ACPI_HANDLE          cpu_handle;
    uint32_t             acpi_id;       /* ACPI processor id */
    uint32_t             cpu_p_blk;     /* ACPI P_BLK location */
    uint32_t             cpu_p_blk_len; /* P_BLK length (must be 6). */
    struct resource     *cpu_p_cnt;     /* Throttling control register */
    struct acpi_cx       cpu_cx_states[MAX_CX_STATES];
    int                  cpu_cx_count;  /* Number of valid Cx states. */
    int                  cpu_prev_sleep;/* Last idle sleep duration. */
};

#define CPU_GET_REG(reg, width)                                         \
    (bus_space_read_ ## width(rman_get_bustag((reg)),                   \
                      rman_get_bushandle((reg)), 0))
#define CPU_SET_REG(reg, width, val)                                    \
    (bus_space_write_ ## width(rman_get_bustag((reg)),                  \
                       rman_get_bushandle((reg)), 0, (val)))

/*
 * Speeds are stored in counts, from 1 to CPU_MAX_SPEED, and
 * reported to the user in tenths of a percent.
 */
static uint32_t          cpu_duty_offset;
static uint32_t          cpu_duty_width;
#define CPU_MAX_SPEED           (1 << cpu_duty_width)
#define CPU_SPEED_PERCENT(x)    ((1000 * (x)) / CPU_MAX_SPEED)
#define CPU_SPEED_PRINTABLE(x)  (CPU_SPEED_PERCENT(x) / 10),    \
                                (CPU_SPEED_PERCENT(x) % 10)
#define CPU_P_CNT_THT_EN (1<<4)
#define PM_USEC(x)       ((x) >> 2)     /* ~4 clocks per usec (3.57955 Mhz) */

#define ACPI_CPU_NOTIFY_PERF_STATES     0x80    /* _PSS changed. */
#define ACPI_CPU_NOTIFY_CX_STATES       0x81    /* _CST changed. */

#define CPU_QUIRK_NO_C3         0x0001  /* C3-type states are not usable. */
#define CPU_QUIRK_NO_THROTTLE   0x0002  /* Throttling is not usable. */

#define PCI_VENDOR_INTEL        0x8086
#define PCI_DEVICE_82371AB_3    0x7113  /* PIIX4 chipset for quirks. */
#define PCI_REVISION_A_STEP     0
#define PCI_REVISION_B_STEP     1
#define PCI_REVISION_4E         2
#define PCI_REVISION_4M         3

/* Platform hardware resource information. */
static uint32_t          cpu_smi_cmd;   /* Value to write to SMI_CMD. */
static uint8_t           cpu_pstate_cnt;/* Register to take over throttling. */
static uint8_t           cpu_cst_cnt;   /* Indicate we are _CST aware. */
static int               cpu_rid;       /* Driver-wide resource id. */
static int               cpu_quirks;    /* Indicate any hardware bugs. */

/* Runtime state. */
static int               cpu_cx_count;  /* Number of valid states */
static int               cpu_non_c3;    /* Index of lowest non-C3 state. */
static u_int             cpu_cx_stats[MAX_CX_STATES];/* Cx usage history. */

/* Values for sysctl. */
static uint32_t          cpu_throttle_state;
static uint32_t          cpu_throttle_max;
static uint32_t          cpu_throttle_performance;
static uint32_t          cpu_throttle_economy;
static int               cpu_cx_lowest;
static char              cpu_cx_supported[64];

static device_t         *cpu_devices;
static int               cpu_ndevices;
static struct acpi_cpu_softc **cpu_softc;

static struct sysctl_ctx_list   acpi_cpu_sysctl_ctx;
static struct sysctl_oid        *acpi_cpu_sysctl_tree;

static int      acpi_cpu_probe(device_t dev);
static int      acpi_cpu_attach(device_t dev);
static int      acpi_pcpu_get_id(uint32_t idx, uint32_t *acpi_id,
                                 uint32_t *cpu_id);
static int      acpi_cpu_shutdown(device_t dev);
static int      acpi_cpu_throttle_probe(struct acpi_cpu_softc *sc);
static void     acpi_cpu_power_profile(void *arg);
static int      acpi_cpu_cx_probe(struct acpi_cpu_softc *sc);
static int      acpi_cpu_cx_cst(struct acpi_cpu_softc *sc);
static void     acpi_cpu_startup(void *arg);
static void     acpi_cpu_startup_throttling(void);
static void     acpi_cpu_startup_cx(void);
static void     acpi_cpu_throttle_set(uint32_t speed);
static void     acpi_cpu_idle(void);
static void     acpi_cpu_c1(void);
static void     acpi_cpu_notify(ACPI_HANDLE h, UINT32 notify, void *context);
static int      acpi_cpu_quirks(struct acpi_cpu_softc *sc);
static int      acpi_cpu_throttle_sysctl(SYSCTL_HANDLER_ARGS);
static int      acpi_cpu_usage_sysctl(SYSCTL_HANDLER_ARGS);
static int      acpi_cpu_cx_lowest_sysctl(SYSCTL_HANDLER_ARGS);

static device_method_t acpi_cpu_methods[] = {
    /* Device interface */
    DEVMETHOD(device_probe,     acpi_cpu_probe),
    DEVMETHOD(device_attach,    acpi_cpu_attach),
    DEVMETHOD(device_shutdown,  acpi_cpu_shutdown),

    {0, 0}
};

static driver_t acpi_cpu_driver = {
    "cpu",
    acpi_cpu_methods,
    sizeof(struct acpi_cpu_softc),
};

static devclass_t acpi_cpu_devclass;
DRIVER_MODULE(cpu, acpi, acpi_cpu_driver, acpi_cpu_devclass, 0, 0);
MODULE_DEPEND(cpu, acpi, 1, 1, 1);

static int
acpi_cpu_probe(device_t dev)
{
    int                    acpi_id, cpu_id, cx_count;
    ACPI_BUFFER            buf;
    ACPI_HANDLE            handle;
    char                   msg[32];
    ACPI_OBJECT            *obj;
    ACPI_STATUS            status;

    if (acpi_disabled("cpu") || acpi_get_type(dev) != ACPI_TYPE_PROCESSOR)
        return (ENXIO);

    handle = acpi_get_handle(dev);
    if (cpu_softc == NULL)
        cpu_softc = malloc(sizeof(struct acpi_cpu_softc *) *
            SMP_MAXCPU, M_TEMP /* XXX */, M_INTWAIT | M_ZERO);

    /* Get our Processor object. */
    buf.Pointer = NULL;
    buf.Length = ACPI_ALLOCATE_BUFFER;
    status = AcpiEvaluateObject(handle, NULL, NULL, &buf);
    if (ACPI_FAILURE(status)) {
        device_printf(dev, "probe failed to get Processor obj - %s\n",
                      AcpiFormatException(status));
        return (ENXIO);
    }
    obj = (ACPI_OBJECT *)buf.Pointer;
    if (obj->Type != ACPI_TYPE_PROCESSOR) {
        device_printf(dev, "Processor object has bad type %d\n", obj->Type);
        AcpiOsFree(obj);
        return (ENXIO);
    }

    /*
     * Find the processor associated with our unit.  We could use the
     * ProcId as a key, however, some boxes do not have the same values
     * in their Processor object as the ProcId values in the MADT.
     */
    acpi_id = obj->Processor.ProcId;
    AcpiOsFree(obj);
    if (acpi_pcpu_get_id(device_get_unit(dev), &acpi_id, &cpu_id) != 0)
        return (ENXIO);

    /*
     * Check if we already probed this processor.  We scan the bus twice
     * so it's possible we've already seen this one.
     */
    if (cpu_softc[cpu_id] != NULL)
        return (ENXIO);

    /* Get a count of Cx states for our device string. */
    cx_count = 0;
    buf.Pointer = NULL;
    buf.Length = ACPI_ALLOCATE_BUFFER;
    status = AcpiEvaluateObject(handle, "_CST", NULL, &buf);
    if (ACPI_SUCCESS(status)) {
        obj = (ACPI_OBJECT *)buf.Pointer;
        if (ACPI_PKG_VALID(obj, 2))
            acpi_PkgInt32(obj, 0, &cx_count);
        AcpiOsFree(obj);
    } else {
        if (AcpiGbl_FADT->Plvl2Lat <= 100)
            cx_count++;
        if (AcpiGbl_FADT->Plvl3Lat <= 1000)
            cx_count++;
        if (cx_count > 0)
            cx_count++;
    }
    if (cx_count > 0)
        snprintf(msg, sizeof(msg), "ACPI CPU (%d Cx states)", cx_count);
    else
        strlcpy(msg, "ACPI CPU", sizeof(msg));
    device_set_desc_copy(dev, msg);

    /* Mark this processor as in-use and save our derived id for attach. */
    cpu_softc[cpu_id] = (void *)1;
    acpi_set_magic(dev, cpu_id);

    return (0);
}

static int
acpi_cpu_attach(device_t dev)
{
    ACPI_BUFFER            buf;
    ACPI_OBJECT            *obj;
    struct acpi_cpu_softc *sc;
    struct acpi_softc     *acpi_sc;
    ACPI_STATUS            status;
    int                    thr_ret, cx_ret;

    ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);

    ACPI_ASSERTLOCK;

    sc = device_get_softc(dev);
    sc->cpu_dev = dev;
    sc->cpu_handle = acpi_get_handle(dev);
    cpu_softc[acpi_get_magic(dev)] = sc;

    buf.Pointer = NULL;
    buf.Length = ACPI_ALLOCATE_BUFFER;
    status = AcpiEvaluateObject(sc->cpu_handle, NULL, NULL, &buf);
    if (ACPI_FAILURE(status)) {
        device_printf(dev, "attach failed to get Processor obj - %s\n",
                      AcpiFormatException(status));
        return (ENXIO);
    }
    obj = (ACPI_OBJECT *)buf.Pointer;
    sc->cpu_p_blk = obj->Processor.PblkAddress;
    sc->cpu_p_blk_len = obj->Processor.PblkLength;
    sc->acpi_id = obj->Processor.ProcId;
    AcpiOsFree(obj);
    ACPI_DEBUG_PRINT((ACPI_DB_INFO, "acpi_cpu%d: P_BLK at %#x/%d\n",
                     device_get_unit(dev), sc->cpu_p_blk, sc->cpu_p_blk_len));

    acpi_sc = acpi_device_get_parent_softc(dev);
    sysctl_ctx_init(&acpi_cpu_sysctl_ctx);
    acpi_cpu_sysctl_tree = SYSCTL_ADD_NODE(&acpi_cpu_sysctl_ctx,
                                SYSCTL_CHILDREN(acpi_sc->acpi_sysctl_tree),
                                OID_AUTO, "cpu", CTLFLAG_RD, 0, "");

    /* If this is the first device probed, check for quirks. */
    if (device_get_unit(dev) == 0)
        acpi_cpu_quirks(sc);

    /*
     * Probe for throttling and Cx state support.
     * If none of these is present, free up unused resources.
     */
    thr_ret = acpi_cpu_throttle_probe(sc);
    cx_ret = acpi_cpu_cx_probe(sc);
    if (thr_ret == 0 || cx_ret == 0) {
        status = AcpiInstallNotifyHandler(sc->cpu_handle, ACPI_DEVICE_NOTIFY,
                                          acpi_cpu_notify, sc);
        if (device_get_unit(dev) == 0)
            AcpiOsQueueForExecution(OSD_PRIORITY_LO, acpi_cpu_startup, NULL);
    } else {
        sysctl_ctx_free(&acpi_cpu_sysctl_ctx);
    }

    return_VALUE (0);
}

/*
 * Find the nth present CPU and return its pc_cpuid as well as set the
 * pc_acpi_id from the most reliable source.
 */
static int
acpi_pcpu_get_id(uint32_t idx, uint32_t *acpi_id, uint32_t *cpu_id)
{
    struct mdglobaldata *md;
    uint32_t     i;

    KASSERT(acpi_id != NULL, ("Null acpi_id"));
    KASSERT(cpu_id != NULL, ("Null cpu_id"));
    for (i = 0; i <= ncpus; i++) {
        if ((smp_active_mask & (1 << i)) == 0)
            continue;
        md = (struct mdglobaldata *)globaldata_find(i);
        KASSERT(md != NULL, ("no pcpu data for %d", i));
        if (idx-- == 0) {
            /*
             * If pc_acpi_id was not initialized (e.g., a non-APIC UP box)
             * override it with the value from the ASL.  Otherwise, if the
             * two don't match, prefer the MADT-derived value.  Finally,
             * return the pc_cpuid to reference this processor.
             */
            if (md->gd_acpi_id == 0xffffffff)
                 md->gd_acpi_id = *acpi_id;
            else if (md->gd_acpi_id != *acpi_id)
                *acpi_id = md->gd_acpi_id;
            *cpu_id = md->mi.gd_cpuid;
            return (0);
        }
    }

    return (ESRCH);
}

static int
acpi_cpu_shutdown(device_t dev)
{
    ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);

    /* Disable any entry to the idle function. */
    cpu_cx_count = 0;

    /* Signal and wait for all processors to exit acpi_cpu_idle(). */
#ifdef SMP
    /*smp_rendezvous(NULL, NULL, NULL, NULL);*/
    KKASSERT(0);        /* XXX use rendezvous */
#endif
    DELAY(1);

    return_VALUE (0);
}

static int
acpi_cpu_throttle_probe(struct acpi_cpu_softc *sc)
{
    uint32_t             duty_end;
    ACPI_BUFFER          buf;
    ACPI_OBJECT          obj;
    ACPI_GENERIC_ADDRESS gas;
    ACPI_STATUS          status;

    ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);

    ACPI_ASSERTLOCK;

    /* Get throttling parameters from the FADT.  0 means not supported. */
    if (device_get_unit(sc->cpu_dev) == 0) {
        cpu_smi_cmd = AcpiGbl_FADT->SmiCmd;
        cpu_pstate_cnt = AcpiGbl_FADT->PstateCnt;
        cpu_cst_cnt = AcpiGbl_FADT->CstCnt;
        cpu_duty_offset = AcpiGbl_FADT->DutyOffset;
        cpu_duty_width = AcpiGbl_FADT->DutyWidth;
    }
    if (cpu_duty_width == 0 || (cpu_quirks & CPU_QUIRK_NO_THROTTLE) != 0)
        return (ENXIO);

    /* Validate the duty offset/width. */
    duty_end = cpu_duty_offset + cpu_duty_width - 1;
    if (duty_end > 31) {
        device_printf(sc->cpu_dev, "CLK_VAL field overflows P_CNT register\n");
        return (ENXIO);
    }
    if (cpu_duty_offset <= 4 && duty_end >= 4) {
        device_printf(sc->cpu_dev, "CLK_VAL field overlaps THT_EN bit\n");
        return (ENXIO);
    }

    /*
     * If not present, fall back to using the processor's P_BLK to find
     * the P_CNT register.
     *
     * Note that some systems seem to duplicate the P_BLK pointer
     * across multiple CPUs, so not getting the resource is not fatal.
     */
    buf.Pointer = &obj;
    buf.Length = sizeof(obj);
    status = AcpiEvaluateObject(sc->cpu_handle, "_PTC", NULL, &buf);
    if (ACPI_SUCCESS(status)) {
        if (obj.Buffer.Length < sizeof(ACPI_GENERIC_ADDRESS) + 3) {
            device_printf(sc->cpu_dev, "_PTC buffer too small\n");
            return (ENXIO);
        }
        memcpy(&gas, obj.Buffer.Pointer + 3, sizeof(gas));
        sc->cpu_p_cnt = acpi_bus_alloc_gas(sc->cpu_dev, &cpu_rid, &gas);
        if (sc->cpu_p_cnt != NULL) {
            ACPI_DEBUG_PRINT((ACPI_DB_INFO, "acpi_cpu%d: P_CNT from _PTC\n",
                             device_get_unit(sc->cpu_dev)));
        }
    }

    /* If _PTC not present or other failure, try the P_BLK. */
    if (sc->cpu_p_cnt == NULL) {
        /* 
         * The spec says P_BLK must be 6 bytes long.  However, some
         * systems use it to indicate a fractional set of features
         * present so we take anything >= 4.
         */
        if (sc->cpu_p_blk_len < 4)
            return (ENXIO);
        gas.Address = sc->cpu_p_blk;
        gas.AddressSpaceId = ACPI_ADR_SPACE_SYSTEM_IO;
        gas.RegisterBitWidth = 32;
        sc->cpu_p_cnt = acpi_bus_alloc_gas(sc->cpu_dev, &cpu_rid, &gas);
        if (sc->cpu_p_cnt != NULL) {
            ACPI_DEBUG_PRINT((ACPI_DB_INFO, "acpi_cpu%d: P_CNT from P_BLK\n",
                             device_get_unit(sc->cpu_dev)));
        } else {
            device_printf(sc->cpu_dev, "Failed to attach throttling P_CNT\n");
            return (ENXIO);
        }
    }
    cpu_rid++;

    return (0);
}

static int
acpi_cpu_cx_probe(struct acpi_cpu_softc *sc)
{
    ACPI_GENERIC_ADDRESS gas;
    struct acpi_cx      *cx_ptr;
    int                  error;

    ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);

    /* Bus mastering arbitration control is needed for C3. */
    if (AcpiGbl_FADT->V1_Pm2CntBlk == 0 || AcpiGbl_FADT->Pm2CntLen == 0) {
        cpu_quirks |= CPU_QUIRK_NO_C3;
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                         "acpi_cpu%d: No BM control, C3 disabled\n",
                         device_get_unit(sc->cpu_dev)));
    }

    /*
     * First, check for the ACPI 2.0 _CST sleep states object.
     * If not usable, fall back to the P_BLK's P_LVL2 and P_LVL3.
     */
    sc->cpu_cx_count = 0;
    error = acpi_cpu_cx_cst(sc);
    if (error != 0) {
        cx_ptr = sc->cpu_cx_states;

        /* C1 has been required since just after ACPI 1.0 */
        cx_ptr->type = ACPI_STATE_C1;
        cx_ptr->trans_lat = 0;
        cpu_non_c3 = 0;
        cx_ptr++;
        sc->cpu_cx_count++;

        /* 
         * The spec says P_BLK must be 6 bytes long.  However, some systems
         * use it to indicate a fractional set of features present so we
         * take 5 as C2.  Some may also have a value of 7 to indicate
         * another C3 but most use _CST for this (as required) and having
         * "only" C1-C3 is not a hardship.
         */
        if (sc->cpu_p_blk_len < 5)
            goto done;

        /* Validate and allocate resources for C2 (P_LVL2). */
        gas.AddressSpaceId = ACPI_ADR_SPACE_SYSTEM_IO;
        gas.RegisterBitWidth = 8;
        if (AcpiGbl_FADT->Plvl2Lat <= 100) {
            gas.Address = sc->cpu_p_blk + 4;
            cx_ptr->p_lvlx = acpi_bus_alloc_gas(sc->cpu_dev, &cpu_rid, &gas);
            if (cx_ptr->p_lvlx != NULL) {
                cpu_rid++;
                cx_ptr->type = ACPI_STATE_C2;
                cx_ptr->trans_lat = AcpiGbl_FADT->Plvl2Lat;
                cpu_non_c3 = 1;
                cx_ptr++;
                sc->cpu_cx_count++;
            }
        }
        if (sc->cpu_p_blk_len < 6)
            goto done;

        /* Validate and allocate resources for C3 (P_LVL3). */
        if (AcpiGbl_FADT->Plvl3Lat <= 1000 &&
            (cpu_quirks & CPU_QUIRK_NO_C3) == 0) {

            gas.Address = sc->cpu_p_blk + 5;
            cx_ptr->p_lvlx = acpi_bus_alloc_gas(sc->cpu_dev, &cpu_rid, &gas);
            if (cx_ptr->p_lvlx != NULL) {
                cpu_rid++;
                cx_ptr->type = ACPI_STATE_C3;
                cx_ptr->trans_lat = AcpiGbl_FADT->Plvl3Lat;
                cx_ptr++;
                sc->cpu_cx_count++;
            }
        }
    }

done:
    /* If no valid registers were found, don't attach. */
    if (sc->cpu_cx_count == 0)
        return (ENXIO);

    /* Use initial sleep value of 1 sec. to start with lowest idle state. */
    sc->cpu_prev_sleep = 1000000;

    return (0);
}

/*
 * Parse a _CST package and set up its Cx states.  Since the _CST object
 * can change dynamically, our notify handler may call this function
 * to clean up and probe the new _CST package.
 */
static int
acpi_cpu_cx_cst(struct acpi_cpu_softc *sc)
{
    struct       acpi_cx *cx_ptr;
    ACPI_STATUS  status;
    ACPI_BUFFER  buf;
    ACPI_OBJECT *top;
    ACPI_OBJECT *pkg;
    uint32_t     count;
    int          i;

    ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);

    buf.Pointer = NULL;
    buf.Length = ACPI_ALLOCATE_BUFFER;
    status = AcpiEvaluateObject(sc->cpu_handle, "_CST", NULL, &buf);
    if (ACPI_FAILURE(status))
        return (ENXIO);

    /* _CST is a package with a count and at least one Cx package. */
    top = (ACPI_OBJECT *)buf.Pointer;
    if (!ACPI_PKG_VALID(top, 2) || acpi_PkgInt32(top, 0, &count) != 0) {
        device_printf(sc->cpu_dev, "Invalid _CST package\n");
        AcpiOsFree(buf.Pointer);
        return (ENXIO);
    }
    if (count != top->Package.Count - 1) {
        device_printf(sc->cpu_dev, "Invalid _CST state count (%d != %d)\n",
               count, top->Package.Count - 1);
        count = top->Package.Count - 1;
    }
    if (count > MAX_CX_STATES) {
        device_printf(sc->cpu_dev, "_CST has too many states (%d)\n", count);
        count = MAX_CX_STATES;
    }

    /* Set up all valid states. */
    sc->cpu_cx_count = 0;
    cx_ptr = sc->cpu_cx_states;
    for (i = 0; i < count; i++) {
        pkg = &top->Package.Elements[i + 1];
        if (!ACPI_PKG_VALID(pkg, 4) ||
            acpi_PkgInt32(pkg, 1, &cx_ptr->type) != 0 ||
            acpi_PkgInt32(pkg, 2, &cx_ptr->trans_lat) != 0 ||
            acpi_PkgInt32(pkg, 3, &cx_ptr->power) != 0) {

            device_printf(sc->cpu_dev, "Skipping invalid Cx state package\n");
            continue;
        }

        /* Validate the state to see if we should use it. */
        switch (cx_ptr->type) {
        case ACPI_STATE_C1:
            cpu_non_c3 = i;
            cx_ptr++;
            sc->cpu_cx_count++;
            continue;
        case ACPI_STATE_C2:
            if (cx_ptr->trans_lat > 100) {
                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                                 "acpi_cpu%d: C2[%d] not available.\n",
                                 device_get_unit(sc->cpu_dev), i));
                continue;
            }
            cpu_non_c3 = i;
            break;
        case ACPI_STATE_C3:
        default:
            if (cx_ptr->trans_lat > 1000 ||
                (cpu_quirks & CPU_QUIRK_NO_C3) != 0) {

                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                                 "acpi_cpu%d: C3[%d] not available.\n",
                                 device_get_unit(sc->cpu_dev), i));
                continue;
            }
            break;
        }

#ifdef notyet
        /* Free up any previous register. */
        if (cx_ptr->p_lvlx != NULL) {
            bus_release_resource(sc->cpu_dev, 0, 0, cx_ptr->p_lvlx);
            cx_ptr->p_lvlx = NULL;
        }
#endif

        /* Allocate the control register for C2 or C3. */
        acpi_PkgGas(sc->cpu_dev, pkg, 0, &cpu_rid, &cx_ptr->p_lvlx);
        if (cx_ptr->p_lvlx != NULL) {
            cpu_rid++;
            ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                             "acpi_cpu%d: Got C%d - %d latency\n",
                             device_get_unit(sc->cpu_dev), cx_ptr->type,
                             cx_ptr->trans_lat));
            cx_ptr++;
            sc->cpu_cx_count++;
        }
    }
    AcpiOsFree(buf.Pointer);

    return (0);
}

/*
 * Call this *after* all CPUs have been attached.
 */
static void
acpi_cpu_startup(void *arg)
{
    struct acpi_cpu_softc *sc;
    int count, i;

    /* Get set of CPU devices */
    devclass_get_devices(acpi_cpu_devclass, &cpu_devices, &cpu_ndevices);

    /*
     * Make sure all the processors' Cx counts match.  We should probably
     * also check the contents of each.  However, no known systems have
     * non-matching Cx counts so we'll deal with this later.
     */
    count = MAX_CX_STATES;
    for (i = 0; i < cpu_ndevices; i++) {
        sc = device_get_softc(cpu_devices[i]);
        count = min(sc->cpu_cx_count, count);
    }
    cpu_cx_count = count;

    /* Perform throttling and Cx final initialization. */
    sc = device_get_softc(cpu_devices[0]);
    if (sc->cpu_p_cnt != NULL)
        acpi_cpu_startup_throttling();
    if (cpu_cx_count > 0)
        acpi_cpu_startup_cx();

    /* register performance profile change handler */
    EVENTHANDLER_REGISTER(power_profile_change, acpi_cpu_power_profile, NULL, 0);
}

/*
 * Power profile change hook.
 *
 * Uses the ACPI lock to avoid reentrancy.
 */
static void
acpi_cpu_power_profile(void *arg)
{
    int state;
    int speed;
    ACPI_LOCK_DECL;

    state = power_profile_get_state();
    if (state != POWER_PROFILE_PERFORMANCE &&
        state != POWER_PROFILE_ECONOMY) {
        return;
    }

    ACPI_LOCK;
    switch(state) {
    case POWER_PROFILE_PERFORMANCE:
        speed = cpu_throttle_performance;
        break;
    case POWER_PROFILE_ECONOMY:
        speed = cpu_throttle_economy;
        break;
    default:
        speed = cpu_throttle_state;
        break;
    }
    if (speed != cpu_throttle_state)
        acpi_cpu_throttle_set(speed);
    ACPI_UNLOCK;
}

/*
 * Takes the ACPI lock to avoid fighting anyone over the SMI command
 * port.
 */
static void
acpi_cpu_startup_throttling()
{
    ACPI_LOCK_DECL;

    /* Initialise throttling states */
    cpu_throttle_max = CPU_MAX_SPEED;
    cpu_throttle_state = CPU_MAX_SPEED;
    cpu_throttle_performance = cpu_throttle_max;
    cpu_throttle_economy = cpu_throttle_performance / 2;

    SYSCTL_ADD_INT(&acpi_cpu_sysctl_ctx,
                   SYSCTL_CHILDREN(acpi_cpu_sysctl_tree),
                   OID_AUTO, "throttle_max", CTLFLAG_RD,
                   &cpu_throttle_max, 0, "maximum CPU speed");
    SYSCTL_ADD_PROC(&acpi_cpu_sysctl_ctx,
                    SYSCTL_CHILDREN(acpi_cpu_sysctl_tree),
                    OID_AUTO, "throttle_state",
                    CTLTYPE_INT | CTLFLAG_RW, &cpu_throttle_state,
                    0, acpi_cpu_throttle_sysctl, "I", "current CPU speed");

    /*
     * Performance/Economy throttle settings
     */
    SYSCTL_ADD_PROC(&acpi_cpu_sysctl_ctx, 
                    SYSCTL_CHILDREN(acpi_cpu_sysctl_tree),
                    OID_AUTO, "performance_speed",
                    CTLTYPE_INT | CTLFLAG_RW, &cpu_throttle_performance,
                    0, acpi_cpu_throttle_sysctl, "I", "performance CPU speed");
    SYSCTL_ADD_PROC(&acpi_cpu_sysctl_ctx,
                    SYSCTL_CHILDREN(acpi_cpu_sysctl_tree),
                    OID_AUTO, "economy_speed",
                    CTLTYPE_INT | CTLFLAG_RW, &cpu_throttle_economy,
                    0, acpi_cpu_throttle_sysctl, "I", "economy CPU speed");

    /* If ACPI 2.0+, signal platform that we are taking over throttling. */
    ACPI_LOCK;
    if (cpu_pstate_cnt != 0)
        AcpiOsWritePort(cpu_smi_cmd, cpu_pstate_cnt, 8);

    /* Set initial speed to maximum. */
    acpi_cpu_throttle_set(cpu_throttle_max);
    ACPI_UNLOCK;

    printf("acpi_cpu: throttling enabled, %d steps (100%% to %d.%d%%), "
           "currently %d.%d%%\n", CPU_MAX_SPEED, CPU_SPEED_PRINTABLE(1),
           CPU_SPEED_PRINTABLE(cpu_throttle_state));
}

/* XXX: not here */
extern void (*cpu_idle_hook)(void);

static void
acpi_cpu_startup_cx()
{
    struct acpi_cpu_softc *sc;
    struct sbuf          sb;
    int i;

    sc = device_get_softc(cpu_devices[0]);
    sbuf_new(&sb, cpu_cx_supported, sizeof(cpu_cx_supported), SBUF_FIXEDLEN);
    for (i = 0; i < cpu_cx_count; i++)
        sbuf_printf(&sb, "C%d/%d ", i + 1, sc->cpu_cx_states[i].trans_lat);
    sbuf_trim(&sb);
    sbuf_finish(&sb);
    SYSCTL_ADD_STRING(&acpi_cpu_sysctl_ctx,
                      SYSCTL_CHILDREN(acpi_cpu_sysctl_tree),
                      OID_AUTO, "cx_supported", CTLFLAG_RD, cpu_cx_supported,
                      0, "Cx/microsecond values for supported Cx states");
    SYSCTL_ADD_PROC(&acpi_cpu_sysctl_ctx,
                    SYSCTL_CHILDREN(acpi_cpu_sysctl_tree),
                    OID_AUTO, "cx_lowest", CTLTYPE_STRING | CTLFLAG_RW,
                    NULL, 0, acpi_cpu_cx_lowest_sysctl, "A",
                    "lowest Cx sleep state to use");
    SYSCTL_ADD_PROC(&acpi_cpu_sysctl_ctx,
                    SYSCTL_CHILDREN(acpi_cpu_sysctl_tree),
                    OID_AUTO, "cx_usage", CTLTYPE_STRING | CTLFLAG_RD,
                    NULL, 0, acpi_cpu_usage_sysctl, "A",
                    "percent usage for each Cx state");

#ifdef notyet
    /* Signal platform that we can handle _CST notification. */
    if (cpu_cst_cnt != 0) {
        ACPI_LOCK;
        AcpiOsWritePort(cpu_smi_cmd, cpu_cst_cnt, 8);
        ACPI_UNLOCK;
    }
#endif

    /* Take over idling from cpu_idle_default_hook(). */
    KKASSERT(0);
    /* XXX only set this if ncpus == 1, for now XXX */
    cpu_idle_hook = acpi_cpu_idle;
}

/*
 * Set CPUs to the new state.
 *
 * Must be called with the ACPI lock held.
 */
static void
acpi_cpu_throttle_set(uint32_t speed)
{
    struct acpi_cpu_softc       *sc;
    int                         i;
    uint32_t                    p_cnt, clk_val;

    ACPI_ASSERTLOCK;

    /* Iterate over processors */
    for (i = 0; i < cpu_ndevices; i++) {
        sc = device_get_softc(cpu_devices[i]);
        if (sc->cpu_p_cnt == NULL)
            continue;

        /* Get the current P_CNT value and disable throttling */
        p_cnt = CPU_GET_REG(sc->cpu_p_cnt, 4);
        p_cnt &= ~CPU_P_CNT_THT_EN;
        CPU_SET_REG(sc->cpu_p_cnt, 4, p_cnt);

        /* If we're at maximum speed, that's all */
        if (speed < CPU_MAX_SPEED) {
            /* Mask the old CLK_VAL off and or-in the new value */
            clk_val = (CPU_MAX_SPEED - 1) << cpu_duty_offset;
            p_cnt &= ~clk_val;
            p_cnt |= (speed << cpu_duty_offset);

            /* Write the new P_CNT value and then enable throttling */
            CPU_SET_REG(sc->cpu_p_cnt, 4, p_cnt);
            p_cnt |= CPU_P_CNT_THT_EN;
            CPU_SET_REG(sc->cpu_p_cnt, 4, p_cnt);
        }
        ACPI_VPRINT(sc->cpu_dev, acpi_device_get_parent_softc(sc->cpu_dev),
                    "set speed to %d.%d%%\n", CPU_SPEED_PRINTABLE(speed));
    }
    cpu_throttle_state = speed;
}

/*
 * Idle the CPU in the lowest state possible.  This function is called with
 * interrupts disabled.  Note that once it re-enables interrupts, a task
 * switch can occur so do not access shared data (i.e. the softc) after
 * interrupts are re-enabled.
 */
static void
acpi_cpu_idle()
{
    struct      acpi_cpu_softc *sc;
    struct      acpi_cx *cx_next;
    uint32_t    start_time, end_time;
    int         bm_active, cx_next_idx, i;

    /* If disabled, return immediately. */
    if (cpu_cx_count == 0) {
        ACPI_ENABLE_IRQS();
        return;
    }

    /*
     * Look up our CPU id to get our softc.  If it's NULL, we'll use C1
     * since there is no ACPI processor object for this CPU.  This occurs
     * for logical CPUs in the HTT case.
     */
    sc = cpu_softc[mdcpu->mi.gd_cpuid];
    if (sc == NULL) {
        acpi_cpu_c1();
        return;
    }

    /*
     * If we slept 100 us or more, use the lowest Cx state.  Otherwise,
     * find the lowest state that has a latency less than or equal to
     * the length of our last sleep.
     */
    cx_next_idx = cpu_cx_lowest;
    if (sc->cpu_prev_sleep < 100)
        for (i = cpu_cx_lowest; i >= 0; i--)
            if (sc->cpu_cx_states[i].trans_lat <= sc->cpu_prev_sleep) {
                cx_next_idx = i;
                break;
            }

    /*
     * Check for bus master activity.  If there was activity, clear
     * the bit and use the lowest non-C3 state.  Note that the USB
     * driver polling for new devices keeps this bit set all the
     * time if USB is loaded.
     */
    AcpiGetRegister(ACPI_BITREG_BUS_MASTER_STATUS, &bm_active,
                    ACPI_MTX_DO_NOT_LOCK);
    if (bm_active != 0) {
        AcpiSetRegister(ACPI_BITREG_BUS_MASTER_STATUS, 1,
                        ACPI_MTX_DO_NOT_LOCK);
        cx_next_idx = min(cx_next_idx, cpu_non_c3);
    }

    /* Select the next state and update statistics. */
    cx_next = &sc->cpu_cx_states[cx_next_idx];
    cpu_cx_stats[cx_next_idx]++;
    KASSERT(cx_next->type != ACPI_STATE_C0, ("acpi_cpu_idle: C0 sleep"));

    /*
     * Execute HLT (or equivalent) and wait for an interrupt.  We can't
     * calculate the time spent in C1 since the place we wake up is an
     * ISR.  Assume we slept one quantum and return.
     */
    if (cx_next->type == ACPI_STATE_C1) {
        sc->cpu_prev_sleep = 1000000 / hz;
        acpi_cpu_c1();
        return;
    }

    /* For C3, disable bus master arbitration and enable bus master wake. */
    if (cx_next->type == ACPI_STATE_C3) {
        AcpiSetRegister(ACPI_BITREG_ARB_DISABLE, 1, ACPI_MTX_DO_NOT_LOCK);
        AcpiSetRegister(ACPI_BITREG_BUS_MASTER_RLD, 1, ACPI_MTX_DO_NOT_LOCK);
    }

    /*
     * Read from P_LVLx to enter C2(+), checking time spent asleep.
     * Use the ACPI timer for measuring sleep time.  Since we need to
     * get the time very close to the CPU start/stop clock logic, this
     * is the only reliable time source.
     */
    AcpiHwLowLevelRead(32, &start_time, &AcpiGbl_FADT->XPmTmrBlk);
    CPU_GET_REG(cx_next->p_lvlx, 1);

    /*
     * Read the end time twice.  Since it may take an arbitrary time
     * to enter the idle state, the first read may be executed before
     * the processor has stopped.  Doing it again provides enough
     * margin that we are certain to have a correct value.
     */
    AcpiHwLowLevelRead(32, &end_time, &AcpiGbl_FADT->XPmTmrBlk);
    AcpiHwLowLevelRead(32, &end_time, &AcpiGbl_FADT->XPmTmrBlk);

    /* Enable bus master arbitration and disable bus master wakeup. */
    if (cx_next->type == ACPI_STATE_C3) {
        AcpiSetRegister(ACPI_BITREG_ARB_DISABLE, 0, ACPI_MTX_DO_NOT_LOCK);
        AcpiSetRegister(ACPI_BITREG_BUS_MASTER_RLD, 0, ACPI_MTX_DO_NOT_LOCK);
    }

    /* Find the actual time asleep in microseconds, minus overhead. */
    end_time = acpi_TimerDelta(end_time, start_time);
    sc->cpu_prev_sleep = PM_USEC(end_time) - cx_next->trans_lat;
    ACPI_ENABLE_IRQS();
}

/* Put the CPU in C1 in a machine-dependant way. */
static void
acpi_cpu_c1()
{
#ifdef __ia64__
    ia64_call_pal_static(PAL_HALT_LIGHT, 0, 0, 0);
#else
    splz();
#ifdef SMP
    if (!lwkt_runnable())
        __asm __volatile("sti; hlt");
    else
        __asm __volatile("sti; pause");
#else
    if (!lwkt_runnable())
        __asm __volatile("sti; hlt");
    else
        __asm __volatile("sti");
#endif
#endif /* !__ia64__ */
}

/*
 * Re-evaluate the _PSS and _CST objects when we are notified that they
 * have changed.
 *
 * XXX Re-evaluation disabled until locking is done.
 */
static void
acpi_cpu_notify(ACPI_HANDLE h, UINT32 notify, void *context)
{
    struct acpi_cpu_softc *sc = (struct acpi_cpu_softc *)context;

    switch (notify) {
    case ACPI_CPU_NOTIFY_PERF_STATES:
        device_printf(sc->cpu_dev, "Performance states changed\n");
        /* acpi_cpu_px_available(sc); */
        break;
    case ACPI_CPU_NOTIFY_CX_STATES:
        device_printf(sc->cpu_dev, "Cx states changed\n");
        /* acpi_cpu_cx_cst(sc); */
        break;
    default:
        device_printf(sc->cpu_dev, "Unknown notify %#x\n", notify);
        break;
    }
}

static int
acpi_cpu_quirks(struct acpi_cpu_softc *sc)
{

    /*
     * C3 is not supported on multiple CPUs since this would require
     * flushing all caches which is currently too expensive.
     */
    if (ncpus > 1)
        cpu_quirks |= CPU_QUIRK_NO_C3;

#ifdef notyet
    /* Look for various quirks of the PIIX4 part. */
    acpi_dev = pci_find_device(PCI_VENDOR_INTEL, PCI_DEVICE_82371AB_3);
    if (acpi_dev != NULL) {
        switch (pci_get_revid(acpi_dev)) {
        /*
         * Disable throttling control on PIIX4 A and B-step.
         * See specification changes #13 ("Manual Throttle Duty Cycle")
         * and #14 ("Enabling and Disabling Manual Throttle"), plus
         * erratum #5 ("STPCLK# Deassertion Time") from the January
         * 2002 PIIX4 specification update.  Note that few (if any)
         * mobile systems ever used this part.
         */
        case PCI_REVISION_A_STEP:
        case PCI_REVISION_B_STEP:
            cpu_quirks |= CPU_QUIRK_NO_THROTTLE;
            /* FALLTHROUGH */
        /*
         * Disable C3 support for all PIIX4 chipsets.  Some of these parts
         * do not report the BMIDE status to the BM status register and
         * others have a livelock bug if Type-F DMA is enabled.  Linux
         * works around the BMIDE bug by reading the BM status directly
         * but we take the simpler approach of disabling C3 for these
         * parts.
         *
         * See erratum #18 ("C3 Power State/BMIDE and Type-F DMA
         * Livelock") from the January 2002 PIIX4 specification update.
         * Applies to all PIIX4 models.
         */
        case PCI_REVISION_4E:
        case PCI_REVISION_4M:
            cpu_quirks |= CPU_QUIRK_NO_C3;
            break;
        default:
            break;
        }
    }
#endif

    return (0);
}

/* Handle changes in the CPU throttling setting. */
static int
acpi_cpu_throttle_sysctl(SYSCTL_HANDLER_ARGS)
{
    uint32_t    *argp;
    uint32_t     arg;
    int          error;
    ACPI_LOCK_DECL;

    argp = (uint32_t *)oidp->oid_arg1;
    arg = *argp;
    error = sysctl_handle_int(oidp, &arg, 0, req);

    /* Error or no new value */
    if (error != 0 || req->newptr == NULL)
        return (error);
    if (arg < 1 || arg > cpu_throttle_max)
        return (EINVAL);

    /* If throttling changed, notify the BIOS of the new rate. */
    ACPI_LOCK;
    if (*argp != arg) {
        *argp = arg;
        acpi_cpu_throttle_set(arg);
    }
    ACPI_UNLOCK;

    return (0);
}

static int
acpi_cpu_usage_sysctl(SYSCTL_HANDLER_ARGS)
{
    struct sbuf  sb;
    char         buf[128];
    int          i;
    uintmax_t    fract, sum, whole;

    sum = 0;
    for (i = 0; i < cpu_cx_count; i++)
        sum += cpu_cx_stats[i];
    sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN);
    for (i = 0; i < cpu_cx_count; i++) {
        if (sum > 0) {
            whole = (uintmax_t)cpu_cx_stats[i] * 100;
            fract = (whole % sum) * 100;
            sbuf_printf(&sb, "%u.%02u%% ", (u_int)(whole / sum),
                (u_int)(fract / sum));
        } else
            sbuf_printf(&sb, "0%% ");
    }
    sbuf_trim(&sb);
    sbuf_finish(&sb);
    sysctl_handle_string(oidp, sbuf_data(&sb), sbuf_len(&sb), req);
    sbuf_delete(&sb);

    return (0);
}

static int
acpi_cpu_cx_lowest_sysctl(SYSCTL_HANDLER_ARGS)
{
    struct       acpi_cpu_softc *sc;
    char         state[8];
    int          val, error, i;

    sc = device_get_softc(cpu_devices[0]);
    snprintf(state, sizeof(state), "C%d", cpu_cx_lowest + 1);
    error = sysctl_handle_string(oidp, state, sizeof(state), req);
    if (error != 0 || req->newptr == NULL)
        return (error);
    if (strlen(state) < 2 || toupper(state[0]) != 'C')
        return (EINVAL);
    val = (int) strtol(state + 1, NULL, 10) - 1;
    if (val < 0 || val > cpu_cx_count - 1)
        return (EINVAL);

    cpu_cx_lowest = val;

    /* If not disabling, cache the new lowest non-C3 state. */
    cpu_non_c3 = 0;
    for (i = cpu_cx_lowest; i >= 0; i--) {
        if (sc->cpu_cx_states[i].type < ACPI_STATE_C3) {
            cpu_non_c3 = i;
            break;
        }
    }

    /* Reset the statistics counters. */
    bzero(cpu_cx_stats, sizeof(cpu_cx_stats));

    return (0);
}