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/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/acpi.h>
#include <linux/dmi.h>
#include <linux/moduleparam.h>
#include <linux/sched.h>	/* need_resched() */
#include <linux/latency.h>

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

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

#define ACPI_PROCESSOR_COMPONENT        0x01000000
#define ACPI_PROCESSOR_CLASS            "processor"
#define _COMPONENT              ACPI_PROCESSOR_COMPONENT
ACPI_MODULE_NAME("processor_idle");
#define ACPI_PROCESSOR_FILE_POWER	"power"
#define US_TO_PM_TIMER_TICKS(t)		((t * (PM_TIMER_FREQUENCY/1000)) / 1000)
#define C2_OVERHEAD			4	/* 1us (3.579 ticks per us) */
#define C3_OVERHEAD			4	/* 1us (3.579 ticks per us) */
static void (*pm_idle_save) (void) __read_mostly;
module_param(max_cstate, uint, 0644);

static unsigned int nocst __read_mostly;
module_param(nocst, uint, 0000);

/*
 * bm_history -- bit-mask with a bit per jiffy of bus-master activity
 * 1000 HZ: 0xFFFFFFFF: 32 jiffies = 32ms
 * 800 HZ: 0xFFFFFFFF: 32 jiffies = 40ms
 * 100 HZ: 0x0000000F: 4 jiffies = 40ms
 * reduce history for more aggressive entry into C3
 */
static unsigned int bm_history __read_mostly =
    (HZ >= 800 ? 0xFFFFFFFF : ((1U << (HZ / 25)) - 1));
module_param(bm_history, uint, 0644);
/* --------------------------------------------------------------------------
                                Power Management
   -------------------------------------------------------------------------- */

/*
 * 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(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)id->driver_data, ACPI_PROCESSOR_MAX_POWER + 1);

	max_cstate = (long)id->driver_data;

	return 0;
}

/* Actually this shouldn't be __cpuinitdata, would be better to fix the
   callers to only run once -AK */
static struct dmi_system_id __cpuinitdata processor_power_dmi_table[] = {
	{ set_max_cstate, "IBM ThinkPad R40e", {
	  DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
	  DMI_MATCH(DMI_BIOS_VERSION,"1SET70WW")}, (void *)1},
	{ set_max_cstate, "IBM ThinkPad R40e", {
	  DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
	  DMI_MATCH(DMI_BIOS_VERSION,"1SET60WW")}, (void *)1},
	{ set_max_cstate, "IBM ThinkPad R40e", {
	  DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
	  DMI_MATCH(DMI_BIOS_VERSION,"1SET43WW") }, (void*)1},
	{ set_max_cstate, "IBM ThinkPad R40e", {
	  DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
	  DMI_MATCH(DMI_BIOS_VERSION,"1SET45WW") }, (void*)1</