449 lines
12 KiB
C
449 lines
12 KiB
C
/*
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* intel_idle.c - native hardware idle loop for modern Intel processors
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*
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* Copyright (c) 2010, Intel Corporation.
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* Len Brown <len.brown@intel.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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/*
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* intel_idle is a cpuidle driver that loads on specific Intel processors
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* in lieu of the legacy ACPI processor_idle driver. The intent is to
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* make Linux more efficient on these processors, as intel_idle knows
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* more than ACPI, as well as make Linux more immune to ACPI BIOS bugs.
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*/
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/*
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* Design Assumptions
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*
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* All CPUs have same idle states as boot CPU
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*
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* Chipset BM_STS (bus master status) bit is a NOP
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* for preventing entry into deep C-stats
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*/
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/*
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* Known limitations
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*
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* The driver currently initializes for_each_online_cpu() upon modprobe.
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* It it unaware of subsequent processors hot-added to the system.
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* This means that if you boot with maxcpus=n and later online
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* processors above n, those processors will use C1 only.
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*
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* ACPI has a .suspend hack to turn off deep c-statees during suspend
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* to avoid complications with the lapic timer workaround.
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* Have not seen issues with suspend, but may need same workaround here.
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*
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* There is currently no kernel-based automatic probing/loading mechanism
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* if the driver is built as a module.
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*/
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/* un-comment DEBUG to enable pr_debug() statements */
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#define DEBUG
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#include <linux/kernel.h>
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#include <linux/cpuidle.h>
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#include <linux/clockchips.h>
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#include <linux/hrtimer.h> /* ktime_get_real() */
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#include <trace/events/power.h>
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#include <linux/sched.h>
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#include <asm/mwait.h>
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#define INTEL_IDLE_VERSION "0.4"
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#define PREFIX "intel_idle: "
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static struct cpuidle_driver intel_idle_driver = {
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.name = "intel_idle",
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.owner = THIS_MODULE,
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};
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/* intel_idle.max_cstate=0 disables driver */
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static int max_cstate = MWAIT_MAX_NUM_CSTATES - 1;
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static unsigned int mwait_substates;
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/* Reliable LAPIC Timer States, bit 1 for C1 etc. */
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static unsigned int lapic_timer_reliable_states = (1 << 1); /* Default to only C1 */
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static struct cpuidle_device __percpu *intel_idle_cpuidle_devices;
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static int intel_idle(struct cpuidle_device *dev, struct cpuidle_state *state);
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static struct cpuidle_state *cpuidle_state_table;
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/*
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* States are indexed by the cstate number,
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* which is also the index into the MWAIT hint array.
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* Thus C0 is a dummy.
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*/
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static struct cpuidle_state nehalem_cstates[MWAIT_MAX_NUM_CSTATES] = {
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{ /* MWAIT C0 */ },
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{ /* MWAIT C1 */
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.name = "NHM-C1",
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.desc = "MWAIT 0x00",
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.driver_data = (void *) 0x00,
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.flags = CPUIDLE_FLAG_TIME_VALID,
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.exit_latency = 3,
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.target_residency = 6,
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.enter = &intel_idle },
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{ /* MWAIT C2 */
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.name = "NHM-C3",
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.desc = "MWAIT 0x10",
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.driver_data = (void *) 0x10,
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.flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
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.exit_latency = 20,
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.target_residency = 80,
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.enter = &intel_idle },
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{ /* MWAIT C3 */
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.name = "NHM-C6",
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.desc = "MWAIT 0x20",
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.driver_data = (void *) 0x20,
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.flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
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.exit_latency = 200,
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.target_residency = 800,
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.enter = &intel_idle },
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};
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static struct cpuidle_state snb_cstates[MWAIT_MAX_NUM_CSTATES] = {
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{ /* MWAIT C0 */ },
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{ /* MWAIT C1 */
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.name = "SNB-C1",
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.desc = "MWAIT 0x00",
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.driver_data = (void *) 0x00,
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.flags = CPUIDLE_FLAG_TIME_VALID,
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.exit_latency = 1,
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.target_residency = 4,
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.enter = &intel_idle },
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{ /* MWAIT C2 */
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.name = "SNB-C3",
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.desc = "MWAIT 0x10",
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.driver_data = (void *) 0x10,
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.flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
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.exit_latency = 80,
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.target_residency = 160,
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.enter = &intel_idle },
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{ /* MWAIT C3 */
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.name = "SNB-C6",
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.desc = "MWAIT 0x20",
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.driver_data = (void *) 0x20,
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.flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
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.exit_latency = 104,
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.target_residency = 208,
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.enter = &intel_idle },
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{ /* MWAIT C4 */
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.name = "SNB-C7",
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.desc = "MWAIT 0x30",
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.driver_data = (void *) 0x30,
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.flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
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.exit_latency = 109,
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.target_residency = 300,
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.enter = &intel_idle },
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};
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static struct cpuidle_state atom_cstates[MWAIT_MAX_NUM_CSTATES] = {
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{ /* MWAIT C0 */ },
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{ /* MWAIT C1 */
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.name = "ATM-C1",
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.desc = "MWAIT 0x00",
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.driver_data = (void *) 0x00,
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.flags = CPUIDLE_FLAG_TIME_VALID,
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.exit_latency = 1,
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.target_residency = 4,
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.enter = &intel_idle },
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{ /* MWAIT C2 */
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.name = "ATM-C2",
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.desc = "MWAIT 0x10",
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.driver_data = (void *) 0x10,
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.flags = CPUIDLE_FLAG_TIME_VALID,
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.exit_latency = 20,
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.target_residency = 80,
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.enter = &intel_idle },
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{ /* MWAIT C3 */ },
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{ /* MWAIT C4 */
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.name = "ATM-C4",
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.desc = "MWAIT 0x30",
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.driver_data = (void *) 0x30,
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.flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
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.exit_latency = 100,
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.target_residency = 400,
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.enter = &intel_idle },
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{ /* MWAIT C5 */ },
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{ /* MWAIT C6 */
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.name = "ATM-C6",
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.desc = "MWAIT 0x52",
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.driver_data = (void *) 0x52,
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.flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
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.exit_latency = 140,
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.target_residency = 560,
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.enter = &intel_idle },
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};
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/**
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* intel_idle
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* @dev: cpuidle_device
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* @state: cpuidle state
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*
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*/
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static int intel_idle(struct cpuidle_device *dev, struct cpuidle_state *state)
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{
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unsigned long ecx = 1; /* break on interrupt flag */
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unsigned long eax = (unsigned long)cpuidle_get_statedata(state);
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unsigned int cstate;
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ktime_t kt_before, kt_after;
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s64 usec_delta;
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int cpu = smp_processor_id();
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cstate = (((eax) >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) + 1;
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local_irq_disable();
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/*
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* leave_mm() to avoid costly and often unnecessary wakeups
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* for flushing the user TLB's associated with the active mm.
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*/
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if (state->flags & CPUIDLE_FLAG_TLB_FLUSHED)
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leave_mm(cpu);
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if (!(lapic_timer_reliable_states & (1 << (cstate))))
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clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
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kt_before = ktime_get_real();
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stop_critical_timings();
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#ifndef MODULE
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trace_power_start(POWER_CSTATE, (eax >> 4) + 1, cpu);
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#endif
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if (!need_resched()) {
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__monitor((void *)¤t_thread_info()->flags, 0, 0);
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smp_mb();
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if (!need_resched())
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__mwait(eax, ecx);
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}
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start_critical_timings();
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kt_after = ktime_get_real();
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usec_delta = ktime_to_us(ktime_sub(kt_after, kt_before));
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local_irq_enable();
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if (!(lapic_timer_reliable_states & (1 << (cstate))))
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clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
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return usec_delta;
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}
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/*
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* intel_idle_probe()
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*/
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static int intel_idle_probe(void)
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{
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unsigned int eax, ebx, ecx;
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if (max_cstate == 0) {
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pr_debug(PREFIX "disabled\n");
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return -EPERM;
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}
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if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
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return -ENODEV;
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if (!boot_cpu_has(X86_FEATURE_MWAIT))
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return -ENODEV;
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if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
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return -ENODEV;
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cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates);
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if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
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!(ecx & CPUID5_ECX_INTERRUPT_BREAK))
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return -ENODEV;
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pr_debug(PREFIX "MWAIT substates: 0x%x\n", mwait_substates);
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if (boot_cpu_has(X86_FEATURE_ARAT)) /* Always Reliable APIC Timer */
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lapic_timer_reliable_states = 0xFFFFFFFF;
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if (boot_cpu_data.x86 != 6) /* family 6 */
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return -ENODEV;
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switch (boot_cpu_data.x86_model) {
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case 0x1A: /* Core i7, Xeon 5500 series */
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case 0x1E: /* Core i7 and i5 Processor - Lynnfield Jasper Forest */
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case 0x1F: /* Core i7 and i5 Processor - Nehalem */
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case 0x2E: /* Nehalem-EX Xeon */
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case 0x2F: /* Westmere-EX Xeon */
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lapic_timer_reliable_states = (1 << 1); /* C1 */
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case 0x25: /* Westmere */
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case 0x2C: /* Westmere */
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cpuidle_state_table = nehalem_cstates;
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break;
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case 0x1C: /* 28 - Atom Processor */
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case 0x26: /* 38 - Lincroft Atom Processor */
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lapic_timer_reliable_states = (1 << 1); /* C1 */
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cpuidle_state_table = atom_cstates;
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break;
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case 0x2A: /* SNB */
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case 0x2D: /* SNB Xeon */
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cpuidle_state_table = snb_cstates;
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break;
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#ifdef FUTURE_USE
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case 0x17: /* 23 - Core 2 Duo */
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lapic_timer_reliable_states = (1 << 2) | (1 << 1); /* C2, C1 */
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#endif
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default:
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pr_debug(PREFIX "does not run on family %d model %d\n",
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boot_cpu_data.x86, boot_cpu_data.x86_model);
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return -ENODEV;
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}
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pr_debug(PREFIX "v" INTEL_IDLE_VERSION
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" model 0x%X\n", boot_cpu_data.x86_model);
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pr_debug(PREFIX "lapic_timer_reliable_states 0x%x\n",
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lapic_timer_reliable_states);
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return 0;
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}
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/*
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* intel_idle_cpuidle_devices_uninit()
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* unregister, free cpuidle_devices
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*/
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static void intel_idle_cpuidle_devices_uninit(void)
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{
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int i;
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struct cpuidle_device *dev;
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for_each_online_cpu(i) {
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dev = per_cpu_ptr(intel_idle_cpuidle_devices, i);
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cpuidle_unregister_device(dev);
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}
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free_percpu(intel_idle_cpuidle_devices);
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return;
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}
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/*
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* intel_idle_cpuidle_devices_init()
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* allocate, initialize, register cpuidle_devices
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*/
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static int intel_idle_cpuidle_devices_init(void)
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{
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int i, cstate;
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struct cpuidle_device *dev;
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intel_idle_cpuidle_devices = alloc_percpu(struct cpuidle_device);
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if (intel_idle_cpuidle_devices == NULL)
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return -ENOMEM;
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for_each_online_cpu(i) {
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dev = per_cpu_ptr(intel_idle_cpuidle_devices, i);
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dev->state_count = 1;
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for (cstate = 1; cstate < MWAIT_MAX_NUM_CSTATES; ++cstate) {
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int num_substates;
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if (cstate > max_cstate) {
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printk(PREFIX "max_cstate %d reached\n",
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max_cstate);
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break;
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}
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/* does the state exist in CPUID.MWAIT? */
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num_substates = (mwait_substates >> ((cstate) * 4))
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& MWAIT_SUBSTATE_MASK;
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if (num_substates == 0)
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continue;
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/* is the state not enabled? */
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if (cpuidle_state_table[cstate].enter == NULL) {
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/* does the driver not know about the state? */
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if (*cpuidle_state_table[cstate].name == '\0')
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pr_debug(PREFIX "unaware of model 0x%x"
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" MWAIT %d please"
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" contact lenb@kernel.org",
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boot_cpu_data.x86_model, cstate);
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continue;
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}
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if ((cstate > 2) &&
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!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
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mark_tsc_unstable("TSC halts in idle"
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" states deeper than C2");
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dev->states[dev->state_count] = /* structure copy */
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cpuidle_state_table[cstate];
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dev->state_count += 1;
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}
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dev->cpu = i;
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if (cpuidle_register_device(dev)) {
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pr_debug(PREFIX "cpuidle_register_device %d failed!\n",
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i);
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intel_idle_cpuidle_devices_uninit();
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return -EIO;
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}
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}
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return 0;
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}
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static int __init intel_idle_init(void)
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{
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int retval;
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retval = intel_idle_probe();
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if (retval)
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return retval;
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retval = cpuidle_register_driver(&intel_idle_driver);
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if (retval) {
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printk(KERN_DEBUG PREFIX "intel_idle yielding to %s",
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cpuidle_get_driver()->name);
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return retval;
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}
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retval = intel_idle_cpuidle_devices_init();
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if (retval) {
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cpuidle_unregister_driver(&intel_idle_driver);
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return retval;
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}
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return 0;
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}
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static void __exit intel_idle_exit(void)
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{
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intel_idle_cpuidle_devices_uninit();
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cpuidle_unregister_driver(&intel_idle_driver);
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return;
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}
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module_init(intel_idle_init);
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module_exit(intel_idle_exit);
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module_param(max_cstate, int, 0444);
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MODULE_AUTHOR("Len Brown <len.brown@intel.com>");
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MODULE_DESCRIPTION("Cpuidle driver for Intel Hardware v" INTEL_IDLE_VERSION);
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MODULE_LICENSE("GPL");
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