path: root/drivers/acpi/processor_idle.c

/*
 * processor_idle - idle state submodule to the ACPI processor driver
 *
 *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
 *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
 *  Copyright (C) 2004, 2005 Dominik Brodowski <linux@brodo.de>
 *  Copyright (C) 2004  Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
 *  			- Added processor hotplug support
 *  Copyright (C) 2005  Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
 *  			- Added support for C3 on SMP
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or (at
 *  your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/slab.h>
#include <linux/acpi.h>
#include <linux/dmi.h>
#include <linux/moduleparam.h>
#include <linux/sched.h>	/* need_resched() */
#include <linux/pm_qos.h>
#include <linux/clockchips.h>
#include <linux/cpuidle.h>
#include <linux/irqflags.h>

/*
 * Include the apic definitions for x86 to have the APIC timer related defines
 * available also for UP (on SMP it gets magically included via linux/smp.h).
 * asm/acpi.h is not an option, as it would require more include magic. Also
 * creating an empty asm-ia64/apic.h would just trade pest vs. cholera.
 */
#ifdef CONFIG_X86
#include <asm/apic.h>
#endif

#include <asm/io.h>
#include <asm/uaccess.h>

#include <acpi/acpi_bus.h>
#include <acpi/processor.h>
#include <asm/processor.h>

#define PREFIX "ACPI: "

#define ACPI_PROCESSOR_CLASS            "processor"
#define _COMPONENT              ACPI_PROCESSOR_COMPONENT
ACPI_MODULE_NAME("processor_idle");
#define PM_TIMER_TICK_NS		(1000000000ULL/PM_TIMER_FREQUENCY)
#define C2_OVERHEAD			1	/* 1us */
#define C3_OVERHEAD			1	/* 1us */
#define PM_TIMER_TICKS_TO_US(p)		(((p) * 1000)/(PM_TIMER_FREQUENCY/1000))

static unsigned int max_cstate __read_mostly = ACPI_PROCESSOR_MAX_POWER;
module_param(max_cstate, uint, 0000);
static unsigned int nocst __read_mostly;
module_param(nocst, uint, 0000);
static int bm_check_disable __read_mostly;
module_param(bm_check_disable, uint, 0000);

static unsigned int latency_factor __read_mostly = 2;
module_param(latency_factor, uint, 0644);

static int disabled_by_idle_boot_param(void)
{
	return boot_option_idle_override == IDLE_POLL ||
		boot_option_idle_override == IDLE_FORCE_MWAIT ||
		boot_option_idle_override == IDLE_HALT;
}

/*
 * IBM ThinkPad R40e crashes mysteriously when going into C2 or C3.
 * For now disable this. Probably a bug somewhere else.
 *
 * To skip this limit, boot/load with a large max_cstate limit.
 */
static int set_max_cstate(const struct dmi_system_id *id)
{
	if (max_cstate > ACPI_PROCESSOR_MAX_POWER)
		return 0;

	printk(KERN_NOTICE PREFIX "%s detected - limiting to C%ld max_cstate."
	       " Override with \"processor.max_cstate=%d\"\n", id->ident,
	       (long)