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/pm_qos_params.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 ACPI_PROCESSOR_CLASS            "processor"
#define _COMPONENT              ACPI_PROCESSOR_COMPONENT
ACPI_MODULE_NAME("processor_idle");
#define ACPI_PROCESSOR_FILE_POWER	"power"
#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 unsigned int latency_factor __read_mostly = 2;
module_param(latency_factor, uint, 0644);

static s64 us_to_pm_timer_ticks(s64 t)
{
	return div64_u64(t * PM_TIMER_FREQUENCY, 1000000);
}
/*
 * 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)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, "Clevo 5600D", {
	  DMI_MATCH(DMI_BIOS_VENDOR,"Phoenix Technologies LTD"),
	  DMI_MATCH(DMI_BIOS_VERSION,"SHE845M0.86C.0013.D.0302131307")},
	 (void *)2},
	{},
};


/*
 * Callers should disable interrupts before the call and enable
 * interrupts after return.
 */
static void acpi_safe_halt(void)
{
	current_thread_info()->status &= ~TS_POLLING;
	/*
	 * TS_POLLING-cleared state must be visible before we
	 * test NEED_RESCHED:
	 */
	smp_mb();
	if (!need_resched()) {
		safe_halt();
		local_irq_disable();
	}
	current_thread_info()->status |= TS_POLLING;
}

#ifdef ARCH_APICTIMER_STOPS_ON_C3

/*
 * Some BIOS implementations switch to C3 in the published C2 state.
 * This seems to be a common problem on AMD boxen, but other vendors
 * are affected too. We pick the most conservative approach: we assume
 * that the local APIC stops in both C2 and C3.
 */
static void acpi_timer_check_state(int state, struct acpi_processor *pr,
				   struct acpi_processor_cx *cx)
{
	struct acpi_processor_power *pwr = &pr->power;
	u8 type = local_apic_timer_c2_ok ? ACPI_STATE_C3 : ACPI_STATE_C2;

	if (cpu_has(&cpu_data(pr->id), X86_FEATURE_ARAT))
		return;

	/*
	 * Check, if one of the previous states already marked the lapic
	 * unstable
	 */
	if (pwr->timer_broadcast_on_state < state)
		return;

	if (cx->type >= type)
		pr->power.timer_broadcast_on_state = state;
}

static void acpi_propagate_timer_broadcast(struct acpi_processor *pr)
{
	unsigned long reason;

	reason = pr->power.timer_broadcast_on_state < INT_MAX ?
		CLOCK_EVT_NOTIFY_BROADCAST_ON : CLOCK_EVT_NOTIFY_BROADCAST_OFF;

	clockevents_notify(reason, &pr->id);
}

/* Power(C) State timer broadcast control */
static void acpi_state_timer_broadcast(struct acpi_processor *pr,
				       struct acpi_processor_cx *cx,
				       int broadcast)
{
	int state = cx - pr->power.states;

	if (state >= pr->power.timer_broadcast_on_state) {
		unsigned long reason;

		reason = broadcast ?  CLOCK_EVT_NOTIFY_BROADCAST_ENTER :
			CLOCK_EVT_NOTIFY_BROADCAST_EXIT;
		clockevents_notify(reason, &pr->id);
	}
}

#else

static void acpi_timer_check_state(int state, struct acpi_processor *pr,
				   struct acpi_processor_cx *cstate) { }
static void acpi_propagate_timer_broadcast(struct acpi_processor *pr) { }
static void acpi_state_timer_broadcast(struct acpi_processor *pr,
				       struct acpi_processor_cx *cx,
				       int broadcast)
{
}

#endif

/*
 * Suspend / resume control
 */
static int acpi_idle_suspend;

int acpi_processor_suspend(struct acpi_device * device, pm_message_t state)
{
	acpi_idle_suspend = 1;
	return 0;
}

int acpi_processor_resume(struct acpi_device * device)
{
	acpi_idle_suspend = 0;
	return 0;
}

#if defined (CONFIG_GENERIC_TIME) && defined (CONFIG_X86)
static int tsc_halts_in_c(int state)
{
	switch (boot_cpu_data.x86_vendor) {
	case X86_VENDOR_AMD:
	case X86_VENDOR_INTEL:
		/*
		 * AMD Fam10h TSC will tick in all
		 * C/P/S0/S1 states when this bit is set.
		 */
		if (boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
			return 0;

		/*FALL THROUGH*/
	default:
		return state > ACPI_STATE_C1;
	}
}
#endif

static int acpi_processor_get_power_info_fadt(struct acpi_processor *pr)
{

	if (!pr)
		return -EINVAL;

	if (!pr->pblk)
		return -ENODEV;

	/* if info is obtained from pblk/fadt, type equals state */
	pr->power.states[ACPI_STATE_C2].type = ACPI_STATE_C2;
	pr->power.states[ACPI_STATE_C3].type = ACPI_STATE_C3;

#ifndef CONFIG_HOTPLUG_CPU
	/*
	 * Check for P_LVL2_UP flag before entering C2 and above on
	 * an SMP system.
	 */
	if ((num_online_cpus() > 1) &&
	    !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED))
		return -ENODEV;
#endif

	/* determine C2 and C3 address from pblk */
	pr->power.states[ACPI_STATE_C2].address = pr->pblk + 4;
	pr->power.states[ACPI_STATE_C3].address = pr->pblk + 5;

	/* determine latencies from FADT */
	pr->power.states[ACPI_STATE_C2].latency = acpi_gbl_FADT.C2latency;
	pr->power.states[ACPI_STATE_C3].latency = acpi_gbl_FADT.C3latency;

	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
			  "lvl2[0x%08x] lvl3[0x%08x]\n",
			  pr->power.states[ACPI_STATE_C2].address,
			  pr->power.states[ACPI_STATE_C3].address));

	return 0;
}

static int acpi_processor_get_power_info_default(struct acpi_processor *pr)
{
	if (!pr->power.states[ACPI_STATE_C1].valid) {
		/* set the first C-State to C1 */
		/* all processors need to support C1 */
		pr->power.states[ACPI_STATE_C1].type = ACPI_STATE_C1;
		pr->power.states[ACPI_STATE_C1].valid = 1;
		pr->power.states[ACPI_STATE_C1].entry_method = ACPI_CSTATE_HALT;
	}
	/* the C0 state only exists as a filler in our array */
	pr->power.states[ACPI_STATE_C0].valid = 1;
	return 0;
}

static int acpi_processor_get_power_info_cst(struct acpi_processor *pr)
{
	acpi_status status = 0;
	acpi_integer count;
	int current_count;
	int i;
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object *cst;


	if (nocst)
		return -ENODEV;

	current_count = 0;

	status = acpi_evaluate_object(pr->handle, "_CST", NULL, &buffer);
	if (ACPI_FAILURE(status)) {
		ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No _CST, giving up\n"));
		return -ENODEV;
	}

	cst = buffer.pointer;

	/* There must be at least 2 elements */
	if (!cst || (cst->type != ACPI_TYPE_PACKAGE) || cst->package.count < 2) {
		printk(KERN_ERR PREFIX "not enough elements in _CST\n");
		status = -EFAULT;
		goto end;
	}

	count = cst->package.elements[0].integer.value;

	/* Validate number of power states. */
	if (count < 1 || count != cst->package.count - 1) {
		printk(KERN_ERR PREFIX "count given by _CST is not valid\n");
		status = -EFAULT;
		goto end;
	}

	/* Tell driver that at least _CST is supported. */
	pr->flags.has_cst = 1;

	for (i = 1; i <= count; i++) {
		union acpi_object *element;
		union acpi_object *obj;
		struct acpi_power_register *reg;
		struct acpi_processor_cx cx;

		memset(&cx, 0, sizeof(cx));

		element = &(cst->package.elements[i]);
		if (element->type != ACPI_TYPE_PACKAGE)
			continue;

		if (element->package.count != 4)
			continue;

		obj = &(element->package.elements[0]);

		if (obj->type != ACPI_TYPE_BUFFER)
			continue;

		reg = (struct acpi_power_register *)obj->buffer.pointer;

		if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_IO &&
		    (reg->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE))
			continue;

		/* There should be an easy way to extract an integer... */
		obj = &(element->package.elements[1]);
		if (obj->type != ACPI_TYPE_INTEGER)
			continue;

		cx.type = obj->integer.value;
		/*
		 * Some buggy BIOSes won't list C1 in _CST -
		 * Let acpi_processor_get_power_info_default() handle them later
		 */
		if (i == 1 && cx.type != ACPI_STATE_C1)
			current_count++;

		cx.address = reg->address;
		cx.index = current_count + 1;

		cx.entry_method = ACPI_CSTATE_SYSTEMIO;
		if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
			if (acpi_processor_ffh_cstate_probe
					(pr->id, &cx, reg) == 0) {
				cx.entry_method = ACPI_CSTATE_FFH;
			} else if (cx.type == ACPI_STATE_C1) {
				/*
				 * C1 is a special case where FIXED_HARDWARE
				 * can be handled in non-MWAIT way as well.
				 * In that case, save this _CST entry info.
				 * Otherwise, ignore this info and continue.
				 */
				cx.entry_method = ACPI_CSTATE_HALT;
				snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI HLT");
			} else {
				continue;
			}
			if (cx.type == ACPI_STATE_C1 &&
					(idle_halt || idle_nomwait)) {
				/*
				 * In most cases the C1 space_id obtained from
				 * _CST object is FIXED_HARDWARE access mode.
				 * But when the option of idle=halt is added,
				 * the entry_method type should be changed from
				 * CSTATE_FFH to CSTATE_HALT.
				 * When the option of idle=nomwait is added,
				 * the C1 entry_method type should be
				 * CSTATE_HALT.
				 */
				cx.entry_method = ACPI_CSTATE_HALT;
				snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI HLT");
			}
		} else {
			snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI IOPORT 0x%x",
				 cx.address);
		}

		if (cx.type == ACPI_STATE_C1) {
			cx.valid = 1;
		}

		obj = &(element->package.elements[2]);
		if (obj->type != ACPI_TYPE_INTEGER)
			continue;

		cx.latency = obj->integer.value;

		obj = &(element->package.elements[3]);
		if (obj->type != ACPI_TYPE_INTEGER)
			continue;

		cx.power = obj->integer.value;

		current_count++;
		memcpy(&(pr->power.states[current_count]), &cx, sizeof(cx));

		/*
		 * We support total ACPI_PROCESSOR_MAX_POWER - 1
		 * (From 1 through ACPI_PROCESSOR_MAX_POWER - 1)
		 */
		if (current_count >= (ACPI_PROCESSOR_MAX_POWER - 1)) {
			printk(KERN_WARNING
			       "Limiting number of power states to max (%d)\n",
			       ACPI_PROCESSOR_MAX_POWER);
			printk(KERN_WARNING
			       "Please increase ACPI_PROCESSOR_MAX_POWER if needed.\n");
			break;
		}
	}

	ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d power states\n",
			  current_count));

	/* Validate number of power states discovered */
	if (current_count < 2)
		status = -EFAULT;

      end:
	kfree(buffer.pointer);

	return status;
}

static void acpi_processor_power_verify_c2(struct acpi_processor_cx *cx)
{

	if (!cx->address)
		return;

	/*
	 * C2 latency must be less than or equal to 100
	 * microseconds.
	 */
	else if (cx->latency > ACPI_PROCESSOR_MAX_C2_LATENCY) {
		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
				  "latency too large [%d]\n", cx->latency));
		return;
	}

	/*
	 * Otherwise we've met all of our C2 requirements.
	 * Normalize the C2 latency to expidite policy
	 */
	cx->valid = 1;

	cx->latency_ticks = cx->latency;

	return;
}

static void acpi_processor_power_verify_c3(struct acpi_processor *pr,
					   struct acpi_processor_cx *cx)
{
	static int bm_check_flag;


	if (!cx->address)
		return;

	/*
	 * C3 latency must be less than or equal to 1000
	 * microseconds.
	 */
	else if (cx->latency > ACPI_PROCESSOR_MAX_C3_LATENCY) {
		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
				  "latency too large [%d]\n", cx->latency));
		return;
	}

	/*
	 * PIIX4 Erratum #18: We don't support C3 when Type-F (fast)
	 * DMA transfers are used by any ISA device to avoid livelock.
	 * Note that we could disable Type-F DMA (as recommended by
	 * the erratum), but this is known to disrupt certain ISA
	 * devices thus we take the conservative approach.
	 */
	else if (errata.piix4.fdma) {
		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
				  "C3 not supported on PIIX4 with Type-F DMA\n"));
		return;
	}

	/* All the logic here assumes flags.bm_check is same across all CPUs */
	if (!bm_check_flag) {
		/* Determine whether bm_check is needed based on CPU  */
		acpi_processor_power_init_bm_check(&(pr->flags), pr->id);
		bm_check_flag = pr->flags.bm_check;
	} else {
		pr->flags.bm_check = bm_check_flag;
	}

	if (pr->flags.bm_check) {
		if (!pr->flags.bm_control) {
			if (pr->flags.has_cst != 1) {
				/* bus mastering control is necessary */
				ACPI_DEBUG_PRINT((ACPI_DB_INFO,
					"C3 support requires BM control\n"));
				return;
			} else {
				/* Here we enter C3 without bus mastering */
				ACPI_DEBUG_PRINT((ACPI_DB_INFO,
					"C3 support without BM control\n"));
			}
		}
	} else {
		/*
		 * WBINVD should be set in fadt, for C3 state to be
		 * supported on when bm_check is not required.
		 */
		if (!(acpi_gbl_FADT.flags & ACPI_FADT_WBINVD)) {
			ACPI_DEBUG_PRINT((ACPI_DB_INFO,
					  "Cache invalidation should work properly"
					  " for C3 to be enabled on SMP systems\n"));
			return;
		}
	}

	/*
	 * Otherwise we've met all of our C3 requirements.
	 * Normalize the C3 latency to expidite policy.  Enable
	 * checking of bus mastering status (bm_check) so we can
	 * use this in our C3 policy
	 */
	cx->valid = 1;

	cx->latency_ticks = cx->latency;
	/*
	 * On older chipsets, BM_RLD needs to be set
	 * in order for Bus Master activity to wake the
	 * system from C3.  Newer chipsets handle DMA
	 * during C3 automatically and BM_RLD is a NOP.
	 * In either case, the proper way to
	 * handle BM_RLD is to set it and leave it set.
	 */
	acpi_write_bit_register(ACPI_BITREG_BUS_MASTER_RLD, 1);

	return;
}

static int acpi_processor_power_verify(struct acpi_processor *pr)
{
	unsigned int i;
	unsigned int working = 0;

	pr->power.timer_broadcast_on_state = INT_MAX;

	for (i = 1; i < ACPI_PROCESSOR_MAX_POWER; i++) {
		struct acpi_processor_cx *cx = &pr->power.states[i];

		switch (cx->type) {
		case ACPI_STATE_C1:
			cx->valid = 1;
			break;

		case ACPI_STATE_C2:
			acpi_processor_power_verify_c2(cx);
			if (cx->valid)
				acpi_timer_check_state(i, pr, cx);
			break;

		case ACPI_STATE_C3:
			acpi_processor_power_verify_c3(pr, cx);
			if (cx->valid)
				acpi_timer_check_state(i, pr, cx);
			break;
		}

		if (cx->valid)
			working++;
	}

	acpi_propagate_timer_broadcast(pr);

	return (working);
}

static int acpi_processor_get_power_info(struct acpi_processor *pr)
{
	unsigned int i;
	int result;


	/* NOTE: the idle thread may not be running while calling
	 * this function */

	/* Zero initialize all the C-states info. */
	memset(pr->power.states, 0, sizeof(pr->power.states));

	result = acpi_processor_get_power_info_cst(pr);
	if (result == -ENODEV)
		result = acpi_processor_get_power_info_fadt(pr);

	if (result)
		return result;

	acpi_processor_get_power_info_default(pr);

	pr->power.count = acpi_processor_power_verify(pr);

	/*
	 * if one state of type C2 or C3 is available, mark this
	 * CPU as being "idle manageable"
	 */
	for (i = 1; i < ACPI_PROCESSOR_MAX_POWER; i++) {
		if (pr->power.states[i].valid) {
			pr->power.count = i;
			if (pr->power.states[i].type >= ACPI_STATE_C2)
				pr->flags.power = 1;
		}
	}

	return 0;
}

static int acpi_processor_power_seq_show(struct seq_file *seq, void *offset)
{
	struct acpi_processor *pr = seq->private;
	unsigned int i;


	if (!pr)
		goto end;

	seq_printf(seq, "active state:            C%zd\n"
		   "max_cstate:              C%d\n"
		   "bus master activity:     %08x\n"
		   "maximum allowed latency: %d usec\n",
		   pr->power.state ? pr->power.state - pr->power.states : 0,
		   max_cstate, (unsigned)pr->power.bm_activity,
		   pm_qos_requirement(PM_QOS_CPU_DMA_LATENCY));

	seq_puts(seq, "states:\n");

	for (i = 1; i <= pr->power.count; i++) {
		seq_printf(seq, "   %cC%d:                  ",
			   (&pr->power.states[i] ==
			    pr->power.state ? '*' : ' '), i);

		if (!pr->power.states[i].valid) {
			seq_puts(seq, "<not supported>\n");
			continue;
		}

		switch (pr->power.states[i].type) {
		case ACPI_STATE_C1:
			seq_printf(seq, "type[C1] ");
			break;
		case ACPI_STATE_C2:
			seq_printf(seq, "type[C2] ");
			break;
		case ACPI_STATE_C3:
			seq_printf(seq, "type[C3] ");
			break;
		default:
			seq_printf(seq, "type[--] ");
			break;
		}

		if (pr->power.states[i].promotion.state)
			seq_printf(seq, "promotion[C%zd] ",
				   (pr->power.states[i].promotion.state -
				    pr->power.states));
		else
			seq_puts(seq, "promotion[--] ");

		if (pr->power.states[i].demotion.state)
			seq_printf(seq, "demotion[C%zd] ",
				   (pr->power.states[i].demotion.state -
				    pr->power.states));
		else
			seq_puts(seq, "demotion[--] ");

		seq_printf(seq, "latency[%03d] usage[%08d] duration[%020llu]\n",
			   pr->power.states[i].latency,
			   pr->power.states[i].usage,
			   (unsigned long long)pr->power.states[i].time);
	}

      end:
	return 0;
}

static int acpi_processor_power_open_fs(struct inode *inode, struct file *file)
{
	return single_open(file, acpi_processor_power_seq_show,
			   PDE(inode)->data);
}

static const struct file_operations acpi_processor_power_fops = {
	.owner = THIS_MODULE,
	.open = acpi_processor_power_open_fs,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = single_release,
};


/**
 * acpi_idle_bm_check - checks if bus master activity was detected
 */
static int acpi_idle_bm_check(void)
{
	u32 bm_status = 0;

	acpi_read_bit_register(ACPI_BITREG_BUS_MASTER_STATUS, &bm_status);
	if (bm_status)
		acpi_write_bit_register(ACPI_BITREG_BUS_MASTER_STATUS, 1);
	/*
	 * PIIX4 Erratum #18: Note that BM_STS doesn't always reflect
	 * the true state of bus mastering activity; forcing us to
	 * manually check the BMIDEA bit of each IDE channel.
	 */
	else if (errata.piix4.bmisx) {
		if ((inb_p(errata.piix4.bmisx + 0x02) & 0x01)
		    || (inb_p(errata.piix4.bmisx + 0x0A) & 0x01))
			bm_status = 1;
	}
	return bm_status;
}

/**
 * acpi_idle_do_entry - a helper function that does C2 and C3 type entry
 * @cx: cstate data
 *
 * Caller disables interrupt before call and enables interrupt after return.
 */
static inline void acpi_idle_do_entry(struct acpi_processor_cx *cx)
{
	/* Don't trace irqs off for idle */
	stop_critical_timings();
	if (cx->entry_method == ACPI_CSTATE_FFH) {
		/* Call into architectural FFH based C-state */
		acpi_processor_ffh_cstate_enter(cx);
	} else if (cx->entry_method == ACPI_CSTATE_HALT) {
		acpi_safe_halt();
	} else {
		int unused;
		/* IO port based C-state */
		inb(cx->address);
		/* Dummy wait op - must do something useless after P_LVL2 read
		   because chipsets cannot guarantee that STPCLK# signal
		   gets asserted in time to freeze execution properly. */
		unused = inl(acpi_gbl_FADT.xpm_timer_block.address);
	}
	start_critical_timings();
}

/**
 * acpi_idle_enter_c1 - enters an ACPI C1 state-type
 * @dev: the target CPU
 * @state: the state data
 *
 * This is equivalent to the HALT instruction.
 */
static int acpi_idle_enter_c1(struct cpuidle_device *dev,
			      struct cpuidle_state *state)
{
	ktime_t  kt1, kt2;
	s64 idle_time;
	struct acpi_processor *pr;
	struct acpi_processor_cx *cx = cpuidle_get_statedata(state);

	pr = __get_cpu_var(processors);

	if (unlikely(!pr))
		return 0;

	local_irq_disable();

	/* Do not access any ACPI IO ports in suspend path */
	if (acpi_idle_suspend) {
		acpi_safe_halt();
		local_irq_enable();
		return 0;
	}

	kt1 = ktime_get_real();
	acpi_idle_do_entry(cx);
	kt2 = ktime_get_real();
	idle_time =  ktime_to_us(ktime_sub(kt2, kt1));

	local_irq_enable();
	cx->usage++;

	return idle_time;
}

/**
 * acpi_idle_enter_simple - enters an ACPI state without BM handling
 * @dev: the target CPU
 * @state: the state data
 */
static int acpi_idle_enter_simple(struct cpuidle_device *dev,
				  struct cpuidle_state *state)
{
	struct acpi_processor *pr;
	struct acpi_processor_cx *cx = cpuidle_get_statedata(state);
	ktime_t  kt1, kt2;
	s64 idle_time;
	s64 sleep_ticks = 0;

	pr = __get_cpu_var(processors);

	if (unlikely(!pr))
		return 0;

	if (acpi_idle_suspend)
		return(acpi_idle_enter_c1(dev, state));

	local_irq_disable();
	current_thread_info()->status &= ~TS_POLLING;
	/*
	 * TS_POLLING-cleared state must be visible before we test
	 * NEED_RESCHED:
	 */
	smp_mb();

	if (unlikely(need_resched())) {
		current_thread_info()->status |= TS_POLLING;
		local_irq_enable();
		return 0;
	}

	/*
	 * Must be done before busmaster disable as we might need to
	 * access HPET !
	 */
	acpi_state_timer_broadcast(pr, cx, 1);

	if (cx->type == ACPI_STATE_C3)
		ACPI_FLUSH_CPU_CACHE();

	kt1 = ktime_get_real();
	/* Tell the scheduler that we are going deep-idle: */
	sched_clock_idle_sleep_event();
	acpi_idle_do_entry(cx);
	kt2 = ktime_get_real();
	idle_time =  ktime_to_us(ktime_sub(kt2, kt1));

#if defined (CONFIG_GENERIC_TIME) && defined (CONFIG_X86)
	/* TSC could halt in idle, so notify users */
	if (tsc_halts_in_c(cx->type))
		mark_tsc_unstable("TSC halts in idle");;
#endif
	sleep_ticks = us_to_pm_timer_ticks(idle_time);

	/* Tell the scheduler how much we idled: */
	sched_clock_idle_wakeup_event(sleep_ticks*PM_TIMER_TICK_NS);

	local_irq_enable();
	current_thread_info()->status |= TS_POLLING;

	cx->usage++;

	acpi_state_timer_broadcast(pr, cx, 0);
	cx->time += sleep_ticks;
	return idle_time;
}

static int c3_cpu_count;
static DEFINE_SPINLOCK(c3_lock);

/**
 * acpi_idle_enter_bm - enters C3 with proper BM handling
 * @dev: the target CPU
 * @state: the state data
 *
 * If BM is detected, the deepest non-C3 idle state is entered instead.
 */
static int acpi_idle_enter_bm(struct cpuidle_device *dev,
			      struct cpuidle_state *state)
{
	struct acpi_processor *pr;
	struct acpi_processor_cx *cx = cpuidle_get_statedata(state);
	ktime_t  kt1, kt2;
	s64 idle_time;
	s64 sleep_ticks = 0;


	pr = __get_cpu_var(processors);

	if (unlikely(!pr))
		return 0;

	if (acpi_idle_suspend)
		return(acpi_idle_enter_c1(dev, state));

	if (acpi_idle_bm_check()) {
		if (dev->safe_state) {
			dev->last_state = dev->safe_state;
			return dev->safe_state->enter(dev, dev->safe_state);
		} else {
			local_irq_disable();
			acpi_safe_halt();
			local_irq_enable();
			return 0;
		}
	}

	local_irq_disable();
	current_thread_info()->status &= ~TS_POLLING;
	/*
	 * TS_POLLING-cleared state must be visible before we test
	 * NEED_RESCHED:
	 */
	smp_mb();

	if (unlikely(need_resched())) {
		current_thread_info()->status |= TS_POLLING;
		local_irq_enable();
		return 0;
	}

	acpi_unlazy_tlb(smp_processor_id());

	/* Tell the scheduler that we are going deep-idle: */
	sched_clock_idle_sleep_event();
	/*
	 * Must be done before busmaster disable as we might need to
	 * access HPET !
	 */
	acpi_state_timer_broadcast(pr, cx, 1);

	/*
	 * disable bus master
	 * bm_check implies we need ARB_DIS
	 * !bm_check implies we need cache flush
	 * bm_control implies whether we can do ARB_DIS
	 *
	 * That leaves a case where bm_check is set and bm_control is
	 * not set. In that case we cannot do much, we enter C3
	 * without doing anything.
	 */
	if (pr->flags.bm_check && pr->flags.bm_control) {
		spin_lock(&c3_lock);
		c3_cpu_count++;
		/* Disable bus master arbitration when all CPUs are in C3 */
		if (c3_cpu_count == num_online_cpus())
			acpi_write_bit_register(ACPI_BITREG_ARB_DISABLE, 1);
		spin_unlock(&c3_lock);
	} else if (!pr->flags.bm_check) {
		ACPI_FLUSH_CPU_CACHE();
	}

	kt1 = ktime_get_real();
	acpi_idle_do_entry(cx);
	kt2 = ktime_get_real();
	idle_time =  ktime_to_us(ktime_sub(kt2, kt1));

	/* Re-enable bus master arbitration */
	if (pr->flags.bm_check && pr->flags.bm_control) {
		spin_lock(&c3_lock);
		acpi_write_bit_register(ACPI_BITREG_ARB_DISABLE, 0);
		c3_cpu_count--;
		spin_unlock(&c3_lock);
	}

#if defined (CONFIG_GENERIC_TIME) && defined (CONFIG_X86)
	/* TSC could halt in idle, so notify users */
	if (tsc_halts_in_c(ACPI_STATE_C3))
		mark_tsc_unstable("TSC halts in idle");
#endif
	sleep_ticks = us_to_pm_timer_ticks(idle_time);
	/* Tell the scheduler how much we idled: */
	sched_clock_idle_wakeup_event(sleep_ticks*PM_TIMER_TICK_NS);

	local_irq_enable();
	current_thread_info()->status |= TS_POLLING;

	cx->usage++;

	acpi_state_timer_broadcast(pr, cx, 0);
	cx->time += sleep_ticks;
	return idle_time;
}

struct cpuidle_driver acpi_idle_driver = {
	.name =		"acpi_idle",
	.owner =	THIS_MODULE,
};

/**
 * acpi_processor_setup_cpuidle - prepares and configures CPUIDLE
 * @pr: the ACPI processor
 */
static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
{
	int i, count = CPUIDLE_DRIVER_STATE_START;
	struct acpi_processor_cx *cx;
	struct cpuidle_state *state;
	struct cpuidle_device *dev = &pr->power.dev;

	if (!pr->flags.power_setup_done)
		return -EINVAL;

	if (pr->flags.power == 0) {
		return -EINVAL;
	}

	dev->cpu = pr->id;
	for (i = 0; i < CPUIDLE_STATE_MAX; i++) {
		dev->states[i].name[0] = '\0';
		dev->states[i].desc[0] = '\0';
	}

	for (i = 1; i < ACPI_PROCESSOR_MAX_POWER && i <= max_cstate; i++) {
		cx = &pr->power.states[i];
		state = &dev->states[count];

		if (!cx->valid)
			continue;

#ifdef CONFIG_HOTPLUG_CPU
		if ((cx->type != ACPI_STATE_C1) && (num_online_cpus() > 1) &&
		    !pr->flags.has_cst &&
		    !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED))
			continue;
#endif
		cpuidle_set_statedata(state, cx);

		snprintf(state->name, CPUIDLE_NAME_LEN, "C%d", i);
		strncpy(state->desc, cx->desc, CPUIDLE_DESC_LEN);
		state->exit_latency = cx->latency;
		state->target_residency = cx->latency * latency_factor;
		state->power_usage = cx->power;

		state->flags = 0;
		switch (cx->type) {
			case ACPI_STATE_C1:
			state->flags |= CPUIDLE_FLAG_SHALLOW;
			if (cx->entry_method == ACPI_CSTATE_FFH)
				state->flags |= CPUIDLE_FLAG_TIME_VALID;

			state->enter = acpi_idle_enter_c1;
			dev->safe_state = state;
			break;

			case ACPI_STATE_C2:
			state->flags |= CPUIDLE_FLAG_BALANCED;
			state->flags |= CPUIDLE_FLAG_TIME_VALID;
			state->enter = acpi_idle_enter_simple;
			dev->safe_state = state;
			break;

			case ACPI_STATE_C3:
			state->flags |= CPUIDLE_FLAG_DEEP;
			state->flags |= CPUIDLE_FLAG_TIME_VALID;
			state->flags |= CPUIDLE_FLAG_CHECK_BM;
			state->enter = pr->flags.bm_check ?
					acpi_idle_enter_bm :
					acpi_idle_enter_simple;
			break;
		}

		count++;
		if (count == CPUIDLE_STATE_MAX)
			break;
	}

	dev->state_count = count;

	if (!count)
		return -EINVAL;

	return 0;
}

int acpi_processor_cst_has_changed(struct acpi_processor *pr)
{
	int ret = 0;

	if (boot_option_idle_override)
		return 0;

	if (!pr)
		return -EINVAL;

	if (nocst) {
		return -ENODEV;
	}

	if (!pr->flags.power_setup_done)
		return -ENODEV;

	cpuidle_pause_and_lock();
	cpuidle_disable_device(&pr->power.dev);
	acpi_processor_get_power_info(pr);
	if (pr->flags.power) {
		acpi_processor_setup_cpuidle(pr);
		ret = cpuidle_enable_device(&pr->power.dev);
	}
	cpuidle_resume_and_unlock();

	return ret;
}

int __cpuinit acpi_processor_power_init(struct acpi_processor *pr,
			      struct acpi_device *device)
{
	acpi_status status = 0;
	static int first_run;
	struct proc_dir_entry *entry = NULL;
	unsigned int i;

	if (boot_option_idle_override)
		return 0;

	if (!first_run) {
		if (idle_halt) {
			/*
			 * When the boot option of "idle=halt" is added, halt
			 * is used for CPU IDLE.
			 * In such case C2/C3 is meaningless. So the max_cstate
			 * is set to one.
			 */
			max_cstate = 1;
		}
		dmi_check_system(processor_power_dmi_table);
		max_cstate = acpi_processor_cstate_check(max_cstate);
		if (max_cstate < ACPI_C_STATES_MAX)
			printk(KERN_NOTICE
			       "ACPI: processor limited to max C-state %d\n",
			       max_cstate);
		first_run++;
	}

	if (!pr)
		return -EINVAL;

	if (acpi_gbl_FADT.cst_control && !nocst) {
		status =
		    acpi_os_write_port(acpi_gbl_FADT.smi_command, acpi_gbl_FADT.cst_control, 8);
		if (ACPI_FAILURE(status)) {
			ACPI_EXCEPTION((AE_INFO, status,
					"Notifying BIOS of _CST ability failed"));
		}
	}

	acpi_processor_get_power_info(pr);
	pr->flags.power_setup_done = 1;

	/*
	 * Install the idle handler if processor power management is supported.
	 * Note that we use previously set idle handler will be used on
	 * platforms that only support C1.
	 */
	if (pr->flags.power) {
		acpi_processor_setup_cpuidle(pr);
		if (cpuidle_register_device(&pr->power.dev))
			return -EIO;

		printk(KERN_INFO PREFIX "CPU%d (power states:", pr->id);
		for (i = 1; i <= pr->power.count; i++)
			if (pr->power.states[i].valid)
				printk(" C%d[C%d]", i,
				       pr->power.states[i].type);
		printk(")\n");
	}

	/* 'power' [R] */
	entry = proc_create_data(ACPI_PROCESSOR_FILE_POWER,
				 S_IRUGO, acpi_device_dir(device),
				 &acpi_processor_power_fops,
				 acpi_driver_data(device));
	if (!entry)
		return -EIO;
	return 0;
}

int acpi_processor_power_exit(struct acpi_processor *pr,
			      struct acpi_device *device)
{
	if (boot_option_idle_override)
		return 0;

	cpuidle_unregister_device(&pr->power.dev);
	pr->flags.power_setup_done = 0;

	if (acpi_device_dir(device))
		remove_proc_entry(ACPI_PROCESSOR_FILE_POWER,
				  acpi_device_dir(device));

	return 0;
}