processor_idle.c

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 * acpi_idle_do_entry - a helper function that does C2 and C3 type entry
 * @cx: cstate data
 */
static inline void acpi_idle_do_entry(struct acpi_processor_cx *cx)
{
	if (cx->space_id == ACPI_CSTATE_FFH) {
		/* Call into architectural FFH based C-state */
		acpi_processor_ffh_cstate_enter(cx);
	} 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);
	}
}

/**
 * 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)
{
	struct acpi_processor *pr;
	struct acpi_processor_cx *cx = cpuidle_get_statedata(state);
	pr = processors[smp_processor_id()];

	if (unlikely(!pr))
		return 0;

	if (pr->flags.bm_check)
		acpi_idle_update_bm_rld(pr, cx);

	acpi_safe_halt();

	cx->usage++;

	return 0;
}

/**
 * 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);
	u32 t1, t2;
	int sleep_ticks = 0;

	pr = processors[smp_processor_id()];

	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 (pr->flags.bm_check)
		acpi_idle_update_bm_rld(pr, cx);

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

	t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
	/* Tell the scheduler that we are going deep-idle: */
	sched_clock_idle_sleep_event();
	acpi_idle_do_entry(cx);
	t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);

#if defined (CONFIG_GENERIC_TIME) && defined (CONFIG_X86_TSC)
	/* TSC could halt in idle, so notify users */
	mark_tsc_unstable("TSC halts in idle");;
#endif
	sleep_ticks = ticks_elapsed(t1, t2);

	/* 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 ticks_elapsed_in_us(t1, t2);
}

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);
	u32 t1, t2;
	int sleep_ticks = 0;

	pr = processors[smp_processor_id()];

	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) {
			return dev->safe_state->enter(dev, dev->safe_state);
		} else {
			acpi_safe_halt();
			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;
	}

	/* 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);

	acpi_idle_update_bm_rld(pr, cx);

	/*
	 * 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_set_register(ACPI_BITREG_ARB_DISABLE, 1);
		spin_unlock(&c3_lock);
	} else if (!pr->flags.bm_check) {
		ACPI_FLUSH_CPU_CACHE();
	}

	t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
	acpi_idle_do_entry(cx);
	t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);

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

#if defined (CONFIG_GENERIC_TIME) && defined (CONFIG_X86_TSC)
	/* TSC could halt in idle, so notify users */
	mark_tsc_unstable("TSC halts in idle");
#endif
	sleep_ticks = ticks_elapsed(t1, t2);
	/* 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 ticks_elapsed_in_us(t1, t2);
}

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 = 0;
	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;
	}

	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);
		state->exit_latency = cx->latency;
		state->target_residency = cx->latency * 6;
		state->power_usage = cx->power;

		state->flags = 0;
		switch (cx->type) {
			case ACPI_STATE_C1:
			state->flags |= CPUIDLE_FLAG_SHALLOW;
			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++;
	}

	dev->state_count = count;

	if (!count)
		return -EINVAL;

	return 0;
}

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

	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);
	acpi_processor_setup_cpuidle(pr);
	ret = cpuidle_enable_device(&pr->power.dev);
	cpuidle_resume_and_unlock();

	return ret;
}

#endif /* CONFIG_CPU_IDLE */

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 (!first_run) {
		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 !defined (CONFIG_CPU_IDLE) && defined (CONFIG_SMP)
		register_latency_notifier(&acpi_processor_latency_notifier);
#endif
	}

	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) && (!boot_option_idle_override)) {
#ifdef CONFIG_CPU_IDLE
		acpi_processor_setup_cpuidle(pr);
		pr->power.dev.cpu = pr->id;
		if (cpuidle_register_device(&pr->power.dev))
			return -EIO;
#endif

		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");

#ifndef CONFIG_CPU_IDLE
		if (pr->id == 0) {
			pm_idle_save = pm_idle;
			pm_idle = acpi_processor_idle;
		}
#endif
	}

	/* 'power' [R] */
	entry = create_proc_entry(ACPI_PROCESSOR_FILE_POWER,
				  S_IRUGO, acpi_device_dir(device));
	if (!entry)
		return -EIO;
	else {
		entry->proc_fops = &acpi_processor_power_fops;
		entry->data = acpi_driver_data(device);
		entry->owner = THIS_MODULE;
	}

	return 0;
}

int acpi_processor_power_exit(struct acpi_processor *pr,
			      struct acpi_device *device)
{
#ifdef CONFIG_CPU_IDLE
	if ((pr->flags.power) && (!boot_option_idle_override))
		cpuidle_unregister_device(&pr->power.dev);
#endif
	pr->flags.power_setup_done = 0;

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

#ifndef CONFIG_CPU_IDLE

	/* Unregister the idle handler when processor #0 is removed. */
	if (pr->id == 0) {
		pm_idle = pm_idle_save;

		/*
		 * We are about to unload the current idle thread pm callback
		 * (pm_idle), Wait for all processors to update cached/local
		 * copies of pm_idle before proceeding.
		 */
		cpu_idle_wait();
#ifdef CONFIG_SMP
		unregister_latency_notifier(&acpi_processor_latency_notifier);
#endif
	}
#endif

	return 0;
}