freebsd-skq/sys/dev/acpica/acpi_cpu.c
Alexander Motin 3c5c555957 Add several performance optimizations to acpi_cpu_idle().
For C1 and C2 states use cpu_ticks() to measure sleep time instead of much
slower ACPI timer. We can't do it for C3, as TSC may stop there. But it is
less important there as wake up latency is high any way.

For C1 and C2 states do not check/clear bus mastering activity status, as
it is important only for C3. As side effect it can make CPU enter C2 instead
of C3 if last BM activity was two sleeps back (unlike one before), but
that may be even good because of collecting more statistics. Premature BM
wakeup from C3, entered because of overestimation, can easily be worse then
entering C2 from both performance and power consumption points of view.

Together on dual Xeon E5645 system on sequential 512 bytes read test this
change makes cpu_idle_acpi() as fast as simplest cpu_idle_hlt() and only
few percents slower then cpu_idle_mwait(), while deeper states are still
actively used during idle periods.

To help with diagnostics, add C-state type into dev.cpu.X.cx_supported.

Sponsored by:	iXsystems, Inc.
2012-07-31 10:58:50 +00:00

1276 lines
38 KiB
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("$FreeBSD$");
#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>
#if defined(__amd64__) || defined(__i386__)
#include <machine/clock.h>
#endif
#include <sys/rman.h>
#include <contrib/dev/acpica/include/acpi.h>
#include <contrib/dev/acpica/include/accommon.h>
#include <dev/acpica/acpivar.h>
/*
* Support for ACPI Processor devices, including C[1-3] sleep states.
*/
/* 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. */
int cpu_features; /* Child driver supported features. */
/* Runtime state. */
int cpu_non_c3; /* Index of lowest non-C3 state. */
u_int cpu_cx_stats[MAX_CX_STATES];/* Cx usage history. */
/* Values for sysctl. */
struct sysctl_ctx_list cpu_sysctl_ctx;
struct sysctl_oid *cpu_sysctl_tree;
int cpu_cx_lowest;
int cpu_cx_lowest_lim;
char cpu_cx_supported[64];
int cpu_rid;
};
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
#define PIIX4_DEVACTB_REG 0x58
#define PIIX4_BRLD_EN_IRQ0 (1<<0)
#define PIIX4_BRLD_EN_IRQ (1<<1)
#define PIIX4_BRLD_EN_IRQ8 (1<<5)
#define PIIX4_STOP_BREAK_MASK (PIIX4_BRLD_EN_IRQ0 | PIIX4_BRLD_EN_IRQ | PIIX4_BRLD_EN_IRQ8)
#define PIIX4_PCNTRL_BST_EN (1<<10)
/* Allow users to ignore processor orders in MADT. */
static int cpu_unordered;
TUNABLE_INT("debug.acpi.cpu_unordered", &cpu_unordered);
SYSCTL_INT(_debug_acpi, OID_AUTO, cpu_unordered, CTLFLAG_RDTUN,
&cpu_unordered, 0,
"Do not use the MADT to match ACPI Processor objects to CPUs.");
/* 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_quirks; /* Indicate any hardware bugs. */
/* Runtime state. */
static int cpu_disable_idle; /* Disable entry to idle function */
/* Values for sysctl. */
static struct sysctl_ctx_list cpu_sysctl_ctx;
static struct sysctl_oid *cpu_sysctl_tree;
static int cpu_cx_generic;
static int cpu_cx_lowest_lim;
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_cpu_suspend(device_t dev);
static int acpi_cpu_resume(device_t dev);
static int acpi_pcpu_get_id(device_t dev, 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, u_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 void acpi_cpu_cx_probe(struct acpi_cpu_softc *sc);
static void acpi_cpu_generic_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(struct acpi_cpu_softc *sc);
static void acpi_cpu_cx_list(struct acpi_cpu_softc *sc);
static void acpi_cpu_idle(void);
static void acpi_cpu_notify(ACPI_HANDLE h, UINT32 notify, void *context);
static int acpi_cpu_quirks(void);
static int acpi_cpu_usage_sysctl(SYSCTL_HANDLER_ARGS);
static int acpi_cpu_set_cx_lowest(struct acpi_cpu_softc *sc);
static int acpi_cpu_cx_lowest_sysctl(SYSCTL_HANDLER_ARGS);
static int acpi_cpu_global_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, acpi_cpu_suspend),
DEVMETHOD(device_resume, acpi_cpu_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_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),
DEVMETHOD_END
};
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;
ACPI_BUFFER buf;
ACPI_HANDLE handle;
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(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);
/* Mark this processor as in-use and save our derived id for attach. */
cpu_softc[cpu_id] = (void *)1;
acpi_set_private(dev, (void*)(intptr_t)cpu_id);
device_set_desc(dev, "ACPI CPU");
return (0);
}
static int
acpi_cpu_attach(device_t dev)
{
ACPI_BUFFER buf;
ACPI_OBJECT arg[4], *obj;
ACPI_OBJECT_LIST arglist;
struct pcpu *pcpu_data;
struct acpi_cpu_softc *sc;
struct acpi_softc *acpi_sc;
ACPI_STATUS status;
u_int features;
int cpu_id, drv_count, i;
driver_t **drivers;
uint32_t cap_set[3];
/* UUID needed by _OSC evaluation */
static uint8_t cpu_oscuuid[16] = { 0x16, 0xA6, 0x77, 0x40, 0x0C, 0x29,
0xBE, 0x47, 0x9E, 0xBD, 0xD8, 0x70,
0x58, 0x71, 0x39, 0x53 };
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 = (int)(intptr_t)acpi_get_private(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.SmiCommand;
cpu_cst_cnt = AcpiGbl_FADT.CstControl;
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));
/*
* If this is the first cpu we attach, create and initialize the generic
* resources that will be used by all acpi cpu devices.
*/
if (device_get_unit(dev) == 0) {
/* Assume we won't be using generic Cx mode by default */
cpu_cx_generic = FALSE;
/* Install hw.acpi.cpu sysctl tree */
acpi_sc = acpi_device_get_parent_softc(dev);
sysctl_ctx_init(&cpu_sysctl_ctx);
cpu_sysctl_tree = SYSCTL_ADD_NODE(&cpu_sysctl_ctx,
SYSCTL_CHILDREN(acpi_sc->acpi_sysctl_tree), OID_AUTO, "cpu",
CTLFLAG_RD, 0, "node for CPU children");
/* Queue post cpu-probing task handler */
AcpiOsExecute(OSL_NOTIFY_HANDLER, acpi_cpu_startup, NULL);
}
/*
* Before calling any CPU methods, collect child driver feature hints
* and notify ACPI of them. We support unified SMP power control
* so advertise this ourselves. Note this is not the same as independent
* SMP control where each CPU can have different settings.
*/
sc->cpu_features = ACPI_CAP_SMP_SAME | ACPI_CAP_SMP_SAME_C3;
if (devclass_get_drivers(acpi_cpu_devclass, &drivers, &drv_count) == 0) {
for (i = 0; i < drv_count; i++) {
if (ACPI_GET_FEATURES(drivers[i], &features) == 0)
sc->cpu_features |= features;
}
free(drivers, M_TEMP);
}
/*
* CPU capabilities are specified in
* Intel Processor Vendor-Specific ACPI Interface Specification.
*/
if (sc->cpu_features) {
arglist.Pointer = arg;
arglist.Count = 4;
arg[0].Type = ACPI_TYPE_BUFFER;
arg[0].Buffer.Length = sizeof(cpu_oscuuid);
arg[0].Buffer.Pointer = cpu_oscuuid; /* UUID */
arg[1].Type = ACPI_TYPE_INTEGER;
arg[1].Integer.Value = 1; /* revision */
arg[2].Type = ACPI_TYPE_INTEGER;
arg[2].Integer.Value = 1; /* count */
arg[3].Type = ACPI_TYPE_BUFFER;
arg[3].Buffer.Length = sizeof(cap_set); /* Capabilities buffer */
arg[3].Buffer.Pointer = (uint8_t *)cap_set;
cap_set[0] = 0; /* status */
cap_set[1] = sc->cpu_features;
status = AcpiEvaluateObject(sc->cpu_handle, "_OSC", &arglist, NULL);
if (ACPI_SUCCESS(status)) {
if (cap_set[0] != 0)
device_printf(dev, "_OSC returned status %#x\n", cap_set[0]);
}
else {
arglist.Pointer = arg;
arglist.Count = 1;
arg[0].Type = ACPI_TYPE_BUFFER;
arg[0].Buffer.Length = sizeof(cap_set);
arg[0].Buffer.Pointer = (uint8_t *)cap_set;
cap_set[0] = 1; /* revision */
cap_set[1] = 1; /* number of capabilities integers */
cap_set[2] = sc->cpu_features;
AcpiEvaluateObject(sc->cpu_handle, "_PDC", &arglist, NULL);
}
}
/* Probe for Cx state support. */
acpi_cpu_cx_probe(sc);
return (0);
}
static void
acpi_cpu_postattach(void *unused __unused)
{
device_t *devices;
int err;
int i, n;
err = devclass_get_devices(acpi_cpu_devclass, &devices, &n);
if (err != 0) {
printf("devclass_get_devices(acpi_cpu_devclass) failed\n");
return;
}
for (i = 0; i < n; i++)
bus_generic_probe(devices[i]);
for (i = 0; i < n; i++)
bus_generic_attach(devices[i]);
free(devices, M_TEMP);
}
SYSINIT(acpi_cpu, SI_SUB_CONFIGURE, SI_ORDER_MIDDLE,
acpi_cpu_postattach, NULL);
/*
* Disable any entry to the idle function during suspend and re-enable it
* during resume.
*/
static int
acpi_cpu_suspend(device_t dev)
{
int error;
error = bus_generic_suspend(dev);
if (error)
return (error);
cpu_disable_idle = TRUE;
return (0);
}
static int
acpi_cpu_resume(device_t dev)
{
cpu_disable_idle = FALSE;
return (bus_generic_resume(dev));
}
/*
* Find the processor associated with a given ACPI ID. By default,
* use the MADT to map ACPI IDs to APIC IDs and use that to locate a
* processor. Some systems have inconsistent ASL and MADT however.
* For these systems the cpu_unordered tunable can be set in which
* case we assume that Processor objects are listed in the same order
* in both the MADT and ASL.
*/
static int
acpi_pcpu_get_id(device_t dev, uint32_t *acpi_id, uint32_t *cpu_id)
{
struct pcpu *pc;
uint32_t i, idx;
KASSERT(acpi_id != NULL, ("Null acpi_id"));
KASSERT(cpu_id != NULL, ("Null cpu_id"));
idx = device_get_unit(dev);
/*
* If pc_acpi_id for CPU 0 is not initialized (e.g. a non-APIC
* UP box) use the ACPI ID from the first processor we find.
*/
if (idx == 0 && mp_ncpus == 1) {
pc = pcpu_find(0);
if (pc->pc_acpi_id == 0xffffffff)
pc->pc_acpi_id = *acpi_id;
*cpu_id = 0;
return (0);
}
CPU_FOREACH(i) {
pc = pcpu_find(i);
KASSERT(pc != NULL, ("no pcpu data for %d", i));
if (cpu_unordered) {
if (idx-- == 0) {
/*
* If pc_acpi_id doesn't match the ACPI ID from the
* ASL, prefer the MADT-derived value.
*/
if (pc->pc_acpi_id != *acpi_id)
*acpi_id = pc->pc_acpi_id;
*cpu_id = pc->pc_cpuid;
return (0);
}
} else {
if (pc->pc_acpi_id == *acpi_id) {
if (bootverbose)
device_printf(dev,
"Processor %s (ACPI ID %u) -> APIC ID %d\n",
acpi_name(acpi_get_handle(dev)), *acpi_id,
pc->pc_cpuid);
*cpu_id = pc->pc_cpuid;
return (0);
}
}
}
if (bootverbose)
printf("ACPI: Processor %s (ACPI ID %u) ignored\n",
acpi_name(acpi_get_handle(dev)), *acpi_id);
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, u_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);
else
free(ad, M_TEMP);
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;
#if defined(__amd64__) || defined(__i386__)
case CPU_IVAR_NOMINAL_MHZ:
if (tsc_is_invariant) {
*result = (uintptr_t)(atomic_load_acq_64(&tsc_freq) / 1000000);
break;
}
/* FALLTHROUGH */
#endif
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. There is a small race where
* an idle thread have passed this check but not gone to sleep. This
* is ok since device_shutdown() does not free the softc, otherwise
* we'd have to be sure all threads were evicted before returning.
*/
cpu_disable_idle = TRUE;
return_VALUE (0);
}
static void
acpi_cpu_cx_probe(struct acpi_cpu_softc *sc)
{
ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
/* Use initial sleep value of 1 sec. to start with lowest idle state. */
sc->cpu_prev_sleep = 1000000;
sc->cpu_cx_lowest = 0;
sc->cpu_cx_lowest_lim = 0;
/*
* Check for the ACPI 2.0 _CST sleep states object. If we can't find
* any, we'll revert to generic FADT/P_BLK Cx control method which will
* be handled by acpi_cpu_startup. We need to defer to after having
* probed all the cpus in the system before probing for generic Cx
* states as we may already have found cpus with valid _CST packages
*/
if (!cpu_cx_generic && acpi_cpu_cx_cst(sc) != 0) {
/*
* We were unable to find a _CST package for this cpu or there
* was an error parsing it. Switch back to generic mode.
*/
cpu_cx_generic = TRUE;
if (bootverbose)
device_printf(sc->cpu_dev, "switching to generic Cx mode\n");
}
/*
* TODO: _CSD Package should be checked here.
*/
}
static void
acpi_cpu_generic_cx_probe(struct acpi_cpu_softc *sc)
{
ACPI_GENERIC_ADDRESS gas;
struct acpi_cx *cx_ptr;
sc->cpu_cx_count = 0;
cx_ptr = sc->cpu_cx_states;
/* Use initial sleep value of 1 sec. to start with lowest idle state. */
sc->cpu_prev_sleep = 1000000;
/* C1 has been required since just after ACPI 1.0 */
cx_ptr->type = ACPI_STATE_C1;
cx_ptr->trans_lat = 0;
cx_ptr++;
sc->cpu_non_c3 = sc->cpu_cx_count;
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)
return;
/* Validate and allocate resources for C2 (P_LVL2). */
gas.SpaceId = ACPI_ADR_SPACE_SYSTEM_IO;
gas.BitWidth = 8;
if (AcpiGbl_FADT.C2Latency <= 100) {
gas.Address = sc->cpu_p_blk + 4;
acpi_bus_alloc_gas(sc->cpu_dev, &cx_ptr->res_type, &sc->cpu_rid,
&gas, &cx_ptr->p_lvlx, RF_SHAREABLE);
if (cx_ptr->p_lvlx != NULL) {
sc->cpu_rid++;
cx_ptr->type = ACPI_STATE_C2;
cx_ptr->trans_lat = AcpiGbl_FADT.C2Latency;
cx_ptr++;
sc->cpu_non_c3 = sc->cpu_cx_count;
sc->cpu_cx_count++;
}
}
if (sc->cpu_p_blk_len < 6)
return;
/* Validate and allocate resources for C3 (P_LVL3). */
if (AcpiGbl_FADT.C3Latency <= 1000 && !(cpu_quirks & CPU_QUIRK_NO_C3)) {
gas.Address = sc->cpu_p_blk + 5;
acpi_bus_alloc_gas(sc->cpu_dev, &cx_ptr->res_type, &sc->cpu_rid, &gas,
&cx_ptr->p_lvlx, RF_SHAREABLE);
if (cx_ptr->p_lvlx != NULL) {
sc->cpu_rid++;
cx_ptr->type = ACPI_STATE_C3;
cx_ptr->trans_lat = AcpiGbl_FADT.C3Latency;
cx_ptr++;
sc->cpu_cx_count++;
cpu_can_deep_sleep = 1;
}
}
}
/*
* 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;
}
sc->cpu_non_c3 = 0;
sc->cpu_cx_count = 0;
cx_ptr = sc->cpu_cx_states;
/*
* C1 has been required since just after ACPI 1.0.
* Reserve the first slot for it.
*/
cx_ptr->type = ACPI_STATE_C0;
cx_ptr++;
sc->cpu_cx_count++;
/* Set up all valid 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:
if (sc->cpu_cx_states[0].type == ACPI_STATE_C0) {
/* This is the first C1 state. Use the reserved slot. */
sc->cpu_cx_states[0] = *cx_ptr;
} else {
sc->cpu_non_c3 = sc->cpu_cx_count;
cx_ptr++;
sc->cpu_cx_count++;
}
continue;
case ACPI_STATE_C2:
sc->cpu_non_c3 = sc->cpu_cx_count;
break;
case ACPI_STATE_C3:
default:
if ((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;
} else
cpu_can_deep_sleep = 1;
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, &sc->cpu_rid,
&cx_ptr->p_lvlx, RF_SHAREABLE);
if (cx_ptr->p_lvlx) {
sc->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);
/* If C1 state was not found, we need one now. */
cx_ptr = sc->cpu_cx_states;
if (cx_ptr->type == ACPI_STATE_C0) {
cx_ptr->type = ACPI_STATE_C1;
cx_ptr->trans_lat = 0;
}
return (0);
}
/*
* Call this *after* all CPUs have been attached.
*/
static void
acpi_cpu_startup(void *arg)
{
struct acpi_cpu_softc *sc;
int i;
/* Get set of CPU devices */
devclass_get_devices(acpi_cpu_devclass, &cpu_devices, &cpu_ndevices);
/*
* Setup any quirks that might necessary now that we have probed
* all the CPUs
*/
acpi_cpu_quirks();
if (cpu_cx_generic) {
/*
* We are using generic Cx mode, probe for available Cx states
* for all processors.
*/
for (i = 0; i < cpu_ndevices; i++) {
sc = device_get_softc(cpu_devices[i]);
acpi_cpu_generic_cx_probe(sc);
}
} else {
/*
* We are using _CST mode, remove C3 state if necessary.
* As we now know for sure that we will be using _CST mode
* install our notify handler.
*/
for (i = 0; i < cpu_ndevices; i++) {
sc = device_get_softc(cpu_devices[i]);
if (cpu_quirks & CPU_QUIRK_NO_C3) {
sc->cpu_cx_count = sc->cpu_non_c3 + 1;
}
AcpiInstallNotifyHandler(sc->cpu_handle, ACPI_DEVICE_NOTIFY,
acpi_cpu_notify, sc);
}
}
/* Perform Cx final initialization. */
for (i = 0; i < cpu_ndevices; i++) {
sc = device_get_softc(cpu_devices[i]);
acpi_cpu_startup_cx(sc);
}
/* Add a sysctl handler to handle global Cx lowest setting */
SYSCTL_ADD_PROC(&cpu_sysctl_ctx, SYSCTL_CHILDREN(cpu_sysctl_tree),
OID_AUTO, "cx_lowest", CTLTYPE_STRING | CTLFLAG_RW,
NULL, 0, acpi_cpu_global_cx_lowest_sysctl, "A",
"Global lowest Cx sleep state to use");
/* Take over idling from cpu_idle_default(). */
cpu_cx_lowest_lim = 0;
cpu_disable_idle = FALSE;
cpu_idle_hook = acpi_cpu_idle;
}
static void
acpi_cpu_cx_list(struct acpi_cpu_softc *sc)
{
struct sbuf sb;
int i;
/*
* Set up the list of Cx states
*/
sbuf_new(&sb, sc->cpu_cx_supported, sizeof(sc->cpu_cx_supported),
SBUF_FIXEDLEN);
for (i = 0; i < sc->cpu_cx_count; i++)
sbuf_printf(&sb, "C%d/%d/%d ", i + 1, sc->cpu_cx_states[i].type,
sc->cpu_cx_states[i].trans_lat);
sbuf_trim(&sb);
sbuf_finish(&sb);
}
static void
acpi_cpu_startup_cx(struct acpi_cpu_softc *sc)
{
acpi_cpu_cx_list(sc);
SYSCTL_ADD_STRING(&sc->cpu_sysctl_ctx,
SYSCTL_CHILDREN(device_get_sysctl_tree(sc->cpu_dev)),
OID_AUTO, "cx_supported", CTLFLAG_RD,
sc->cpu_cx_supported, 0,
"Cx/microsecond values for supported Cx states");
SYSCTL_ADD_PROC(&sc->cpu_sysctl_ctx,
SYSCTL_CHILDREN(device_get_sysctl_tree(sc->cpu_dev)),
OID_AUTO, "cx_lowest", CTLTYPE_STRING | CTLFLAG_RW,
(void *)sc, 0, acpi_cpu_cx_lowest_sysctl, "A",
"lowest Cx sleep state to use");
SYSCTL_ADD_PROC(&sc->cpu_sysctl_ctx,
SYSCTL_CHILDREN(device_get_sysctl_tree(sc->cpu_dev)),
OID_AUTO, "cx_usage", CTLTYPE_STRING | CTLFLAG_RD,
(void *)sc, 0, acpi_cpu_usage_sysctl, "A",
"percent usage for each Cx state");
/* Signal platform that we can handle _CST notification. */
if (!cpu_cx_generic && cpu_cst_cnt != 0) {
ACPI_LOCK(acpi);
AcpiOsWritePort(cpu_smi_cmd, cpu_cst_cnt, 8);
ACPI_UNLOCK(acpi);
}
}
/*
* 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;
uint64_t cputicks;
uint32_t start_time, end_time;
int bm_active, cx_next_idx, i;
/* If disabled, return immediately. */
if (cpu_disable_idle) {
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;
}
/* Find the lowest state that has small enough latency. */
cx_next_idx = 0;
if (cpu_disable_deep_sleep)
i = min(sc->cpu_cx_lowest, sc->cpu_non_c3);
else
i = sc->cpu_cx_lowest;
for (; i >= 0; i--) {
if (sc->cpu_cx_states[i].trans_lat * 3 <= 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 &&
cx_next_idx > sc->cpu_non_c3) {
AcpiReadBitRegister(ACPI_BITREG_BUS_MASTER_STATUS, &bm_active);
if (bm_active != 0) {
AcpiWriteBitRegister(ACPI_BITREG_BUS_MASTER_STATUS, 1);
cx_next_idx = sc->cpu_non_c3;
}
}
/* Select the next state and update statistics. */
cx_next = &sc->cpu_cx_states[cx_next_idx];
sc->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
* precisely calculate the time spent in C1 since the place we wake up
* is an ISR. Assume we slept no more then half of quantum, unless
* we are called inside critical section, delaying context switch.
*/
if (cx_next->type == ACPI_STATE_C1) {
cputicks = cpu_ticks();
acpi_cpu_c1();
end_time = ((cpu_ticks() - cputicks) << 20) / cpu_tickrate();
if (curthread->td_critnest == 0)
end_time = min(end_time, 500000 / hz);
sc->cpu_prev_sleep = (sc->cpu_prev_sleep * 3 + end_time) / 4;
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) {
AcpiWriteBitRegister(ACPI_BITREG_ARB_DISABLE, 1);
AcpiWriteBitRegister(ACPI_BITREG_BUS_MASTER_RLD, 1);
} 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.
*/
if (cx_next->type == ACPI_STATE_C3) {
AcpiHwRead(&start_time, &AcpiGbl_FADT.XPmTimerBlock);
cputicks = 0;
} else {
start_time = 0;
cputicks = cpu_ticks();
}
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.
*/
AcpiHwRead(&end_time, &AcpiGbl_FADT.XPmTimerBlock);
if (cx_next->type == ACPI_STATE_C3) {
AcpiHwRead(&end_time, &AcpiGbl_FADT.XPmTimerBlock);
end_time = acpi_TimerDelta(end_time, start_time);
} else
end_time = ((cpu_ticks() - cputicks) << 20) / cpu_tickrate();
/* Enable bus master arbitration and disable bus master wakeup. */
if (cx_next->type == ACPI_STATE_C3 &&
(cpu_quirks & CPU_QUIRK_NO_BM_CTRL) == 0) {
AcpiWriteBitRegister(ACPI_BITREG_ARB_DISABLE, 0);
AcpiWriteBitRegister(ACPI_BITREG_BUS_MASTER_RLD, 0);
}
ACPI_ENABLE_IRQS();
sc->cpu_prev_sleep = (sc->cpu_prev_sleep * 3 + PM_USEC(end_time)) / 4;
}
/*
* 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;
/* Update the list of Cx states. */
acpi_cpu_cx_cst(sc);
acpi_cpu_cx_list(sc);
ACPI_SERIAL_BEGIN(cpu);
acpi_cpu_set_cx_lowest(sc);
ACPI_SERIAL_END(cpu);
}
static int
acpi_cpu_quirks(void)
{
device_t acpi_dev;
uint32_t val;
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.Pm2ControlBlock == 0 ||
AcpiGbl_FADT.Pm2ControlLength == 0) {
if ((AcpiGbl_FADT.Flags & ACPI_FADT_WBINVD) &&
(AcpiGbl_FADT.Flags & ACPI_FADT_WBINVD_FLUSH) == 0) {
cpu_quirks |= CPU_QUIRK_NO_BM_CTRL;
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"acpi_cpu: no BM control, using flush cache method\n"));
} else {
cpu_quirks |= CPU_QUIRK_NO_C3;
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"acpi_cpu: no BM control, C3 not available\n"));
}
}
/*
* If we are using generic Cx mode, C3 on multiple CPUs requires using
* the expensive flush cache instruction.
*/
if (cpu_cx_generic && mp_ncpus > 1) {
cpu_quirks |= CPU_QUIRK_NO_BM_CTRL;
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"acpi_cpu: SMP, using flush cache mode for C3\n"));
}
/* 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.
*
* Also, make sure that all interrupts cause a "Stop Break"
* event to exit from C2 state.
* Also, BRLD_EN_BM (ACPI_BITREG_BUS_MASTER_RLD in ACPI-speak)
* should be set to zero, otherwise it causes C2 to short-sleep.
* PIIX4 doesn't properly support C3 and bus master activity
* need not break out of C2.
*/
case PCI_REVISION_A_STEP:
case PCI_REVISION_B_STEP:
case PCI_REVISION_4E:
case PCI_REVISION_4M:
cpu_quirks |= CPU_QUIRK_NO_C3;
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"acpi_cpu: working around PIIX4 bug, disabling C3\n"));
val = pci_read_config(acpi_dev, PIIX4_DEVACTB_REG, 4);
if ((val & PIIX4_STOP_BREAK_MASK) != PIIX4_STOP_BREAK_MASK) {
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"acpi_cpu: PIIX4: enabling IRQs to generate Stop Break\n"));
val |= PIIX4_STOP_BREAK_MASK;
pci_write_config(acpi_dev, PIIX4_DEVACTB_REG, val, 4);
}
AcpiReadBitRegister(ACPI_BITREG_BUS_MASTER_RLD, &val);
if (val) {
ACPI_DEBUG_PRINT((ACPI_DB_INFO,
"acpi_cpu: PIIX4: reset BRLD_EN_BM\n"));
AcpiWriteBitRegister(ACPI_BITREG_BUS_MASTER_RLD, 0);
}
break;
default:
break;
}
}
return (0);
}
static int
acpi_cpu_usage_sysctl(SYSCTL_HANDLER_ARGS)
{
struct acpi_cpu_softc *sc;
struct sbuf sb;
char buf[128];
int i;
uintmax_t fract, sum, whole;
sc = (struct acpi_cpu_softc *) arg1;
sum = 0;
for (i = 0; i < sc->cpu_cx_count; i++)
sum += sc->cpu_cx_stats[i];
sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN);
for (i = 0; i < sc->cpu_cx_count; i++) {
if (sum > 0) {
whole = (uintmax_t)sc->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, "0.00%% ");
}
sbuf_printf(&sb, "last %dus", sc->cpu_prev_sleep);
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_set_cx_lowest(struct acpi_cpu_softc *sc)
{
int i;
ACPI_SERIAL_ASSERT(cpu);
sc->cpu_cx_lowest = min(sc->cpu_cx_lowest_lim, sc->cpu_cx_count - 1);
/* If not disabling, cache the new lowest non-C3 state. */
sc->cpu_non_c3 = 0;
for (i = sc->cpu_cx_lowest; i >= 0; i--) {
if (sc->cpu_cx_states[i].type < ACPI_STATE_C3) {
sc->cpu_non_c3 = i;
break;
}
}
/* Reset the statistics counters. */
bzero(sc->cpu_cx_stats, sizeof(sc->cpu_cx_stats));
return (0);
}
static int
acpi_cpu_cx_lowest_sysctl(SYSCTL_HANDLER_ARGS)
{
struct acpi_cpu_softc *sc;
char state[8];
int val, error;
sc = (struct acpi_cpu_softc *) arg1;
snprintf(state, sizeof(state), "C%d", sc->cpu_cx_lowest_lim + 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);
if (strcasecmp(state, "Cmax") == 0)
val = MAX_CX_STATES;
else {
val = (int) strtol(state + 1, NULL, 10);
if (val < 1 || val > MAX_CX_STATES)
return (EINVAL);
}
ACPI_SERIAL_BEGIN(cpu);
sc->cpu_cx_lowest_lim = val - 1;
acpi_cpu_set_cx_lowest(sc);
ACPI_SERIAL_END(cpu);
return (0);
}
static int
acpi_cpu_global_cx_lowest_sysctl(SYSCTL_HANDLER_ARGS)
{
struct acpi_cpu_softc *sc;
char state[8];
int val, error, i;
snprintf(state, sizeof(state), "C%d", cpu_cx_lowest_lim + 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);
if (strcasecmp(state, "Cmax") == 0)
val = MAX_CX_STATES;
else {
val = (int) strtol(state + 1, NULL, 10);
if (val < 1 || val > MAX_CX_STATES)
return (EINVAL);
}
/* Update the new lowest useable Cx state for all CPUs. */
ACPI_SERIAL_BEGIN(cpu);
cpu_cx_lowest_lim = val - 1;
for (i = 0; i < cpu_ndevices; i++) {
sc = device_get_softc(cpu_devices[i]);
sc->cpu_cx_lowest_lim = cpu_cx_lowest_lim;
acpi_cpu_set_cx_lowest(sc);
}
ACPI_SERIAL_END(cpu);
return (0);
}