FreeBSD/Linux Kernel Cross Reference
sys/dev/acpica/acpi_cpu.c

     /*-
      * Copyright (c) 2003-2005 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.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD: releng/5.4/sys/dev/acpica/acpi_cpu.c 142509 2005-02-25 21:43:38Z njl $");
    
    #include "opt_acpi.h"
    #include <sys/param.h>
    #include <sys/bus.h>
    #include <sys/cpu.h>
    #include <sys/kernel.h>
    #include <sys/malloc.h>
    #include <sys/module.h>
    #include <sys/pcpu.h>
    #include <sys/power.h>
    #include <sys/proc.h>
    #include <sys/sbuf.h>
    #include <sys/smp.h>
    
    #include <dev/pci/pcivar.h>
    #include <machine/atomic.h>
    #include <machine/bus.h>
    #include <sys/rman.h>
    
    #include "acpi.h"
    #include <dev/acpica/acpivar.h>
    
    /*
     * Support for ACPI Processor devices, including 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). */
        int                  res_type;      /* Resource type for p_lvlx. */
    };
    #define MAX_CX_STATES    8
    
    struct acpi_cpu_softc {
        device_t             cpu_dev;
        ACPI_HANDLE          cpu_handle;
        struct pcpu         *cpu_pcpu;
        uint32_t             cpu_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 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. */
    };
    
    struct acpi_cpu_device {
        struct resource_list        ad_rl;
    };
    
    #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)))
    
    #define PM_USEC(x)       ((x) >> 2)     /* ~4 clocks per usec (3.57955 Mhz) */
    
    #define ACPI_NOTIFY_CX_STATES   0x81    /* _CST changed. */
    
    #define CPU_QUIRK_NO_C3         (1<<0)  /* C3-type states are not usable. */
   #define CPU_QUIRK_NO_BM_CTRL    (1<<2)  /* No bus mastering control. */
   
   #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_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 struct sysctl_ctx_list acpi_cpu_sysctl_ctx;
   static struct sysctl_oid *acpi_cpu_sysctl_tree;
   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;
   ACPI_SERIAL_DECL(cpu, "ACPI CPU");
   
   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 struct resource_list *acpi_cpu_get_rlist(device_t dev, device_t child);
   static device_t acpi_cpu_add_child(device_t dev, int order, const char *name,
                       int unit);
   static int      acpi_cpu_read_ivar(device_t dev, device_t child, int index,
                       uintptr_t *result);
   static int      acpi_cpu_shutdown(device_t dev);
   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_cx(void);
   static void     acpi_cpu_idle(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_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_detach,    bus_generic_detach),
       DEVMETHOD(device_shutdown,  acpi_cpu_shutdown),
       DEVMETHOD(device_suspend,   bus_generic_suspend),
       DEVMETHOD(device_resume,    bus_generic_resume),
   
       /* Bus interface */
       DEVMETHOD(bus_add_child,    acpi_cpu_add_child),
       DEVMETHOD(bus_read_ivar,    acpi_cpu_read_ivar),
       DEVMETHOD(bus_get_resource_list, acpi_cpu_get_rlist),
       DEVMETHOD(bus_get_resource, bus_generic_rl_get_resource),
       DEVMETHOD(bus_set_resource, bus_generic_rl_set_resource),
       DEVMETHOD(bus_alloc_resource, bus_generic_rl_alloc_resource),
       DEVMETHOD(bus_release_resource, bus_generic_rl_release_resource),
       DEVMETHOD(bus_driver_added, bus_generic_driver_added),
       DEVMETHOD(bus_activate_resource, bus_generic_activate_resource),
       DEVMETHOD(bus_deactivate_resource, bus_generic_deactivate_resource),
       DEVMETHOD(bus_setup_intr,   bus_generic_setup_intr),
       DEVMETHOD(bus_teardown_intr, bus_generic_teardown_intr),
   
       {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 *) *
               (mp_maxid + 1), M_TEMP /* XXX */, M_WAITOK | 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 pcpu            *pcpu_data;
       struct acpi_cpu_softc *sc;
       struct acpi_softc     *acpi_sc;
       ACPI_STATUS            status;
       int                    cpu_id;
   
       ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
   
       sc = device_get_softc(dev);
       sc->cpu_dev = dev;
       sc->cpu_handle = acpi_get_handle(dev);
       cpu_id = acpi_get_magic(dev);
       cpu_softc[cpu_id] = sc;
       pcpu_data = pcpu_find(cpu_id);
       pcpu_data->pc_device = dev;
       sc->cpu_pcpu = pcpu_data;
       cpu_smi_cmd = AcpiGbl_FADT->SmiCmd;
       cpu_cst_cnt = AcpiGbl_FADT->CstCnt;
   
       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->cpu_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, "");
   
       /*
        * Probe for Cx state support.  If it isn't present, free up unused
        * resources.
        */
       if (acpi_cpu_cx_probe(sc) == 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);
   
       /* Call identify and then probe/attach for cpu child drivers. */
       bus_generic_probe(dev);
       bus_generic_attach(dev);
   
       return (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 pcpu *pcpu_data;
       uint32_t     i;
   
       KASSERT(acpi_id != NULL, ("Null acpi_id"));
       KASSERT(cpu_id != NULL, ("Null cpu_id"));
       for (i = 0; i <= mp_maxid; i++) {
           if (CPU_ABSENT(i))
               continue;
           pcpu_data = pcpu_find(i);
           KASSERT(pcpu_data != 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 (pcpu_data->pc_acpi_id == 0xffffffff)
                    pcpu_data->pc_acpi_id = *acpi_id;
               else if (pcpu_data->pc_acpi_id != *acpi_id)
                   *acpi_id = pcpu_data->pc_acpi_id;
               *cpu_id = pcpu_data->pc_cpuid;
               return (0);
           }
       }
   
       return (ESRCH);
   }
   
   static struct resource_list *
   acpi_cpu_get_rlist(device_t dev, device_t child)
   {
       struct acpi_cpu_device *ad;
   
       ad = device_get_ivars(child);
       if (ad == NULL)
           return (NULL);
       return (&ad->ad_rl);
   }
   
   static device_t
   acpi_cpu_add_child(device_t dev, int order, const char *name, int unit)
   {
       struct acpi_cpu_device  *ad;
       device_t            child;
   
       if ((ad = malloc(sizeof(*ad), M_TEMP, M_NOWAIT | M_ZERO)) == NULL)
           return (NULL);
   
       resource_list_init(&ad->ad_rl);
       
       child = device_add_child_ordered(dev, order, name, unit);
       if (child != NULL)
           device_set_ivars(child, ad);
       return (child);
   }
   
   static int
   acpi_cpu_read_ivar(device_t dev, device_t child, int index, uintptr_t *result)
   {
       struct acpi_cpu_softc *sc;
   
       sc = device_get_softc(dev);
       switch (index) {
       case ACPI_IVAR_HANDLE:
           *result = (uintptr_t)sc->cpu_handle;
           break;
       case CPU_IVAR_PCPU:
           *result = (uintptr_t)sc->cpu_pcpu;
           break;
       default:
           return (ENOENT);
       }
       return (0);
   }
   
   static int
   acpi_cpu_shutdown(device_t dev)
   {
       ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
   
       /* Allow children to shutdown first. */
       bus_generic_shutdown(dev);
   
       /* Disable any entry to the idle function. */
       cpu_cx_count = 0;
   
       /* Signal and wait for all processors to exit acpi_cpu_idle(). */
       smp_rendezvous(NULL, NULL, NULL, NULL);
   
       return_VALUE (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 to keep caches coherent
        * while sleeping in C3.  If it's not present but a working flush cache
        * instruction is present, flush the caches before entering C3 instead.
        * Otherwise, just disable C3 completely.
        */
       if (AcpiGbl_FADT->V1_Pm2CntBlk == 0 || AcpiGbl_FADT->Pm2CntLen == 0) {
           if (AcpiGbl_FADT->WbInvd && AcpiGbl_FADT->WbInvdFlush == 0) {
               cpu_quirks |= CPU_QUIRK_NO_BM_CTRL;
               ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                   "acpi_cpu%d: no BM control, using flush cache method\n",
                   device_get_unit(sc->cpu_dev)));
           } else {
               cpu_quirks |= CPU_QUIRK_NO_C3;
               ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                   "acpi_cpu%d: no BM control, C3 not available\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;
               acpi_bus_alloc_gas(sc->cpu_dev, &cx_ptr->res_type, &cpu_rid, &gas,
                   &cx_ptr->p_lvlx);
               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;
               acpi_bus_alloc_gas(sc->cpu_dev, &cx_ptr->res_type, &cpu_rid, &gas,
                   &cx_ptr->p_lvlx);
               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, &cx_ptr->res_type, &cpu_rid,
               &cx_ptr->p_lvlx);
           if (cx_ptr->p_lvlx) {
               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);
   
       /* Check for quirks via the first CPU device. */
       sc = device_get_softc(cpu_devices[0]);
       acpi_cpu_quirks(sc);
   
       /*
        * 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 Cx final initialization. */
       sc = device_get_softc(cpu_devices[0]);
       if (cpu_cx_count > 0)
           acpi_cpu_startup_cx();
   }
   
   static void
   acpi_cpu_startup_cx()
   {
       struct acpi_cpu_softc *sc;
       struct sbuf sb;
       int i;
   
       /*
        * Set up the list of Cx states, eliminating C3 states by truncating
        * cpu_cx_count if quirks indicate C3 is not usable.
        */
       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++) {
           if ((cpu_quirks & CPU_QUIRK_NO_C3) == 0 ||
               sc->cpu_cx_states[i].type != ACPI_STATE_C3)
               sbuf_printf(&sb, "C%d/%d ", i + 1, sc->cpu_cx_states[i].trans_lat);
           else
               cpu_cx_count = i;
       }
       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(acpi);
           AcpiOsWritePort(cpu_smi_cmd, cpu_cst_cnt, 8);
           ACPI_UNLOCK(acpi);
       }
   #endif
   
       /* Take over idling from cpu_idle_default(). */
       cpu_idle_hook = acpi_cpu_idle;
   }
   
   /*
    * 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[PCPU_GET(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.
        */
       if ((cpu_quirks & CPU_QUIRK_NO_BM_CTRL) == 0) {
           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 BM control is available, otherwise flush the CPU cache.
        */
       if (cx_next->type == ACPI_STATE_C3) {
           if ((cpu_quirks & CPU_QUIRK_NO_BM_CTRL) == 0) {
               AcpiSetRegister(ACPI_BITREG_ARB_DISABLE, 1, ACPI_MTX_DO_NOT_LOCK);
               AcpiSetRegister(ACPI_BITREG_BUS_MASTER_RLD, 1,
                   ACPI_MTX_DO_NOT_LOCK);
           } else
               ACPI_FLUSH_CPU_CACHE();
       }
   
       /*
        * 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 &&
           (cpu_quirks & CPU_QUIRK_NO_BM_CTRL) == 0) {
           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();
   }
   
   /*
    * Re-evaluate the _CST object when we are notified that it 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;
   
       if (notify != ACPI_NOTIFY_CX_STATES)
           return;
   
       device_printf(sc->cpu_dev, "Cx states changed\n");
       /* acpi_cpu_cx_cst(sc); */
   }
   
   static int
   acpi_cpu_quirks(struct acpi_cpu_softc *sc)
   {
       device_t acpi_dev;
   
       /*
        * C3 on multiple CPUs requires using the expensive flush cache
        * instruction.
        */
       if (mp_ncpus > 1)
           cpu_quirks |= CPU_QUIRK_NO_BM_CTRL;
   
       /* 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 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;
           }
       }
   
       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);
   
       ACPI_SERIAL_BEGIN(cpu);
       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));
       ACPI_SERIAL_END(cpu);
   
       return (0);
   }

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