[deliverable/linux.git] / drivers / acpi / acpi_pad.c

/*
 * acpi_pad.c ACPI Processor Aggregator Driver
 *
 * Copyright (c) 2009, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */

#include <linux/kernel.h>
#include <linux/cpumask.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/kthread.h>
#include <linux/freezer.h>
#include <linux/cpu.h>
#include <linux/clockchips.h>
#include <linux/slab.h>
#include <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>

#define ACPI_PROCESSOR_AGGREGATOR_CLASS	"acpi_pad"
#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
static DEFINE_MUTEX(isolated_cpus_lock);

#define MWAIT_SUBSTATE_MASK	(0xf)
#define MWAIT_CSTATE_MASK	(0xf)
#define MWAIT_SUBSTATE_SIZE	(4)
#define CPUID_MWAIT_LEAF (5)
#define CPUID5_ECX_EXTENSIONS_SUPPORTED (0x1)
#define CPUID5_ECX_INTERRUPT_BREAK	(0x2)
static unsigned long power_saving_mwait_eax;

static unsigned char tsc_detected_unstable;
static unsigned char tsc_marked_unstable;

static void power_saving_mwait_init(void)
{
	unsigned int eax, ebx, ecx, edx;
	unsigned int highest_cstate = 0;
	unsigned int highest_subcstate = 0;
	int i;

	if (!boot_cpu_has(X86_FEATURE_MWAIT))
		return;
	if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
		return;

	cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);

	if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
	    !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
		return;

	edx >>= MWAIT_SUBSTATE_SIZE;
	for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
		if (edx & MWAIT_SUBSTATE_MASK) {
			highest_cstate = i;
			highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
		}
	}
	power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
		(highest_subcstate - 1);

	for_each_online_cpu(i)
		clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ON, &i);

#if defined(CONFIG_GENERIC_TIME) && defined(CONFIG_X86)
	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;

		/*FALL THROUGH*/
	default:
		/* TSC could halt in idle */
		tsc_detected_unstable = 1;
	}
#endif
}

static unsigned long cpu_weight[NR_CPUS];
static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1};
static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS);
static void round_robin_cpu(unsigned int tsk_index)
{
	struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
	cpumask_var_t tmp;
	int cpu;
	unsigned long min_weight = -1;
	unsigned long uninitialized_var(preferred_cpu);

	if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
		return;

	mutex_lock(&isolated_cpus_lock);
	cpumask_clear(tmp);
	for_each_cpu(cpu, pad_busy_cpus)
		cpumask_or(tmp, tmp, topology_thread_cpumask(cpu));
	cpumask_andnot(tmp, cpu_online_mask, tmp);
	/* avoid HT sibilings if possible */
	if (cpumask_empty(tmp))
		cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
	if (cpumask_empty(tmp)) {
		mutex_unlock(&isolated_cpus_lock);
		return;
	}
	for_each_cpu(cpu, tmp) {
		if (cpu_weight[cpu] < min_weight) {
			min_weight = cpu_weight[cpu];
			preferred_cpu = cpu;
		}
	}

	if (tsk_in_cpu[tsk_index] != -1)
		cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
	tsk_in_cpu[tsk_index] = preferred_cpu;
	cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
	cpu_weight[preferred_cpu]++;
	mutex_unlock(&isolated_cpus_lock);

	set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
}

static void exit_round_robin(unsigned int tsk_index)
{
	struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
	cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
	tsk_in_cpu[tsk_index] = -1;
}

static unsigned int idle_pct = 5; /* percentage */
static unsigned int round_robin_time = 10; /* second */
static int power_saving_thread(void *data)
{
	struct sched_param param = {.sched_priority = 1};
	int do_sleep;
	unsigned int tsk_index = (unsigned long)data;
	u64 last_jiffies = 0;

	sched_setscheduler(current, SCHED_RR, &param);

	while (!kthread_should_stop()) {
		int cpu;
		u64 expire_time;

		try_to_freeze();

		/* round robin to cpus */
		if (last_jiffies + round_robin_time * HZ < jiffies) {
			last_jiffies = jiffies;
			round_robin_cpu(tsk_index);
		}

		do_sleep = 0;

		expire_time = jiffies + HZ * (100 - idle_pct) / 100;

		while (!need_resched()) {
			if (tsc_detected_unstable && !tsc_marked_unstable) {
				/* TSC could halt in idle, so notify users */
				mark_tsc_unstable("TSC halts in idle");
				tsc_marked_unstable = 1;
			}
			local_irq_disable();
			cpu = smp_processor_id();
			clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
				&cpu);
			stop_critical_timings();

			__monitor((void *)&current_thread_info()->flags, 0, 0);
			smp_mb();
			if (!need_resched())
				__mwait(power_saving_mwait_eax, 1);

			start_critical_timings();
			clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
				&cpu);
			local_irq_enable();

			if (jiffies > expire_time) {
				do_sleep = 1;
				break;
			}
		}

		/*
		 * current sched_rt has threshold for rt task running time.
		 * When a rt task uses 95% CPU time, the rt thread will be
		 * scheduled out for 5% CPU time to not starve other tasks. But
		 * the mechanism only works when all CPUs have RT task running,
		 * as if one CPU hasn't RT task, RT task from other CPUs will
		 * borrow CPU time from this CPU and cause RT task use > 95%
		 * CPU time. To make 'avoid starvation' work, takes a nap here.
		 */
		if (do_sleep)
			schedule_timeout_killable(HZ * idle_pct / 100);
	}

	exit_round_robin(tsk_index);
	return 0;
}

static struct task_struct *ps_tsks[NR_CPUS];
static unsigned int ps_tsk_num;
static int create_power_saving_task(void)
{
	int rc = -ENOMEM;

	ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
		(void *)(unsigned long)ps_tsk_num,
		"power_saving/%d", ps_tsk_num);
	rc = IS_ERR(ps_tsks[ps_tsk_num]) ? PTR_ERR(ps_tsks[ps_tsk_num]) : 0;
	if (!rc)
		ps_tsk_num++;
	else
		ps_tsks[ps_tsk_num] = NULL;

	return rc;
}

static void destroy_power_saving_task(void)
{
	if (ps_tsk_num > 0) {
		ps_tsk_num--;
		kthread_stop(ps_tsks[ps_tsk_num]);
		ps_tsks[ps_tsk_num] = NULL;
	}
}

static void set_power_saving_task_num(unsigned int num)
{
	if (num > ps_tsk_num) {
		while (ps_tsk_num < num) {
			if (create_power_saving_task())
				return;
		}
	} else if (num < ps_tsk_num) {
		while (ps_tsk_num > num)
			destroy_power_saving_task();
	}
}

static void acpi_pad_idle_cpus(unsigned int num_cpus)
{
	get_online_cpus();

	num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
	set_power_saving_task_num(num_cpus);

	put_online_cpus();
}

static uint32_t acpi_pad_idle_cpus_num(void)
{
	return ps_tsk_num;
}

static ssize_t acpi_pad_rrtime_store(struct device *dev,
	struct device_attribute *attr, const char *buf, size_t count)
{
	unsigned long num;
	if (strict_strtoul(buf, 0, &num))
		return -EINVAL;
	if (num < 1 || num >= 100)
		return -EINVAL;
	mutex_lock(&isolated_cpus_lock);
	round_robin_time = num;
	mutex_unlock(&isolated_cpus_lock);
	return count;
}

static ssize_t acpi_pad_rrtime_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	return scnprintf(buf, PAGE_SIZE, "%d", round_robin_time);
}
static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR,
	acpi_pad_rrtime_show,
	acpi_pad_rrtime_store);

static ssize_t acpi_pad_idlepct_store(struct device *dev,
	struct device_attribute *attr, const char *buf, size_t count)
{
	unsigned long num;
	if (strict_strtoul(buf, 0, &num))
		return -EINVAL;
	if (num < 1 || num >= 100)
		return -EINVAL;
	mutex_lock(&isolated_cpus_lock);
	idle_pct = num;
	mutex_unlock(&isolated_cpus_lock);
	return count;
}

static ssize_t acpi_pad_idlepct_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	return scnprintf(buf, PAGE_SIZE, "%d", idle_pct);
}
static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR,
	acpi_pad_idlepct_show,
	acpi_pad_idlepct_store);

static ssize_t acpi_pad_idlecpus_store(struct device *dev,
	struct device_attribute *attr, const char *buf, size_t count)
{
	unsigned long num;
	if (strict_strtoul(buf, 0, &num))
		return -EINVAL;
	mutex_lock(&isolated_cpus_lock);
	acpi_pad_idle_cpus(num);
	mutex_unlock(&isolated_cpus_lock);
	return count;
}

static ssize_t acpi_pad_idlecpus_show(struct device *dev,
	struct device_attribute *attr, char *buf)
{
	return cpumask_scnprintf(buf, PAGE_SIZE,
		to_cpumask(pad_busy_cpus_bits));
}
static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR,
	acpi_pad_idlecpus_show,
	acpi_pad_idlecpus_store);

static int acpi_pad_add_sysfs(struct acpi_device *device)
{
	int result;

	result = device_create_file(&device->dev, &dev_attr_idlecpus);
	if (result)
		return -ENODEV;
	result = device_create_file(&device->dev, &dev_attr_idlepct);
	if (result) {
		device_remove_file(&device->dev, &dev_attr_idlecpus);
		return -ENODEV;
	}
	result = device_create_file(&device->dev, &dev_attr_rrtime);
	if (result) {
		device_remove_file(&device->dev, &dev_attr_idlecpus);
		device_remove_file(&device->dev, &dev_attr_idlepct);
		return -ENODEV;
	}
	return 0;
}

static void acpi_pad_remove_sysfs(struct acpi_device *device)
{
	device_remove_file(&device->dev, &dev_attr_idlecpus);
	device_remove_file(&device->dev, &dev_attr_idlepct);
	device_remove_file(&device->dev, &dev_attr_rrtime);
}

/* Query firmware how many CPUs should be idle */
static int acpi_pad_pur(acpi_handle handle, int *num_cpus)
{
	struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
	union acpi_object *package;
	int rev, num, ret = -EINVAL;

	if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
		return -EINVAL;

	if (!buffer.length || !buffer.pointer)
		return -EINVAL;

	package = buffer.pointer;
	if (package->type != ACPI_TYPE_PACKAGE || package->package.count != 2)
		goto out;
	rev = package->package.elements[0].integer.value;
	num = package->package.elements[1].integer.value;
	if (rev != 1 || num < 0)
		goto out;
	*num_cpus = num;
	ret = 0;
out:
	kfree(buffer.pointer);
	return ret;
}

/* Notify firmware how many CPUs are idle */
static void acpi_pad_ost(acpi_handle handle, int stat,
	uint32_t idle_cpus)
{
	union acpi_object params[3] = {
		{.type = ACPI_TYPE_INTEGER,},
		{.type = ACPI_TYPE_INTEGER,},
		{.type = ACPI_TYPE_BUFFER,},
	};
	struct acpi_object_list arg_list = {3, params};

	params[0].integer.value = ACPI_PROCESSOR_AGGREGATOR_NOTIFY;
	params[1].integer.value =  stat;
	params[2].buffer.length = 4;
	params[2].buffer.pointer = (void *)&idle_cpus;
	acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
}

static void acpi_pad_handle_notify(acpi_handle handle)
{
	int num_cpus;
	uint32_t idle_cpus;

	mutex_lock(&isolated_cpus_lock);
	if (acpi_pad_pur(handle, &num_cpus)) {
		mutex_unlock(&isolated_cpus_lock);
		return;
	}
	acpi_pad_idle_cpus(num_cpus);
	idle_cpus = acpi_pad_idle_cpus_num();
	acpi_pad_ost(handle, 0, idle_cpus);
	mutex_unlock(&isolated_cpus_lock);
}

static void acpi_pad_notify(acpi_handle handle, u32 event,
	void *data)
{
	struct acpi_device *device = data;

	switch (event) {
	case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
		acpi_pad_handle_notify(handle);
		acpi_bus_generate_proc_event(device, event, 0);
		acpi_bus_generate_netlink_event(device->pnp.device_class,
			dev_name(&device->dev), event, 0);
		break;
	default:
		printk(KERN_WARNING"Unsupported event [0x%x]\n", event);
		break;
	}
}

static int acpi_pad_add(struct acpi_device *device)
{
	acpi_status status;

	strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
	strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);

	if (acpi_pad_add_sysfs(device))
		return -ENODEV;

	status = acpi_install_notify_handler(device->handle,
		ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
	if (ACPI_FAILURE(status)) {
		acpi_pad_remove_sysfs(device);
		return -ENODEV;
	}

	return 0;
}

static int acpi_pad_remove(struct acpi_device *device,
	int type)
{
	mutex_lock(&isolated_cpus_lock);
	acpi_pad_idle_cpus(0);
	mutex_unlock(&isolated_cpus_lock);

	acpi_remove_notify_handler(device->handle,
		ACPI_DEVICE_NOTIFY, acpi_pad_notify);
	acpi_pad_remove_sysfs(device);
	return 0;
}

static const struct acpi_device_id pad_device_ids[] = {
	{"ACPI000C", 0},
	{"", 0},
};
MODULE_DEVICE_TABLE(acpi, pad_device_ids);

static struct acpi_driver acpi_pad_driver = {
	.name = "processor_aggregator",
	.class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
	.ids = pad_device_ids,
	.ops = {
		.add = acpi_pad_add,
		.remove = acpi_pad_remove,
	},
};

static int __init acpi_pad_init(void)
{
	power_saving_mwait_init();
	if (power_saving_mwait_eax == 0)
		return -EINVAL;

	return acpi_bus_register_driver(&acpi_pad_driver);
}

static void __exit acpi_pad_exit(void)
{
	acpi_bus_unregister_driver(&acpi_pad_driver);
}

module_init(acpi_pad_init);
module_exit(acpi_pad_exit);
MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
MODULE_LICENSE("GPL");
Commit	Line	Data
8e0af514 SL	1	/*
	2	* acpi_pad.c ACPI Processor Aggregator Driver
	3	*
	4	* Copyright (c) 2009, Intel Corporation.
	5	*
	6	* This program is free software; you can redistribute it and/or modify it
	7	* under the terms and conditions of the GNU General Public License,
	8	* version 2, as published by the Free Software Foundation.
	9	*
	10	* This program is distributed in the hope it will be useful, but WITHOUT
	11	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	12	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
	13	* more details.
	14	*
	15	* You should have received a copy of the GNU General Public License along with
	16	* this program; if not, write to the Free Software Foundation, Inc.,
	17	* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
	18	*
	19	*/
	20
	21	#include <linux/kernel.h>
	22	#include <linux/cpumask.h>
	23	#include <linux/module.h>
	24	#include <linux/init.h>
	25	#include <linux/types.h>
	26	#include <linux/kthread.h>
	27	#include <linux/freezer.h>
	28	#include <linux/cpu.h>
	29	#include <linux/clockchips.h>
5a0e3ad6	30	#include <linux/slab.h>
8e0af514 SL	31	#include <acpi/acpi_bus.h>
	32	#include <acpi/acpi_drivers.h>
	33
a40770a9	34	#define ACPI_PROCESSOR_AGGREGATOR_CLASS "acpi_pad"
8e0af514 SL	35	#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
	36	#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
	37	static DEFINE_MUTEX(isolated_cpus_lock);
	38
	39	#define MWAIT_SUBSTATE_MASK (0xf)
	40	#define MWAIT_CSTATE_MASK (0xf)
	41	#define MWAIT_SUBSTATE_SIZE (4)
	42	#define CPUID_MWAIT_LEAF (5)
	43	#define CPUID5_ECX_EXTENSIONS_SUPPORTED (0x1)
	44	#define CPUID5_ECX_INTERRUPT_BREAK (0x2)
	45	static unsigned long power_saving_mwait_eax;
0dc698b9 VP	46
	47	static unsigned char tsc_detected_unstable;
	48	static unsigned char tsc_marked_unstable;
	49
8e0af514 SL	50	static void power_saving_mwait_init(void)
	51	{
	52	unsigned int eax, ebx, ecx, edx;
	53	unsigned int highest_cstate = 0;
	54	unsigned int highest_subcstate = 0;
	55	int i;
	56
	57	if (!boot_cpu_has(X86_FEATURE_MWAIT))
	58	return;
	59	if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
	60	return;
	61
	62	cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
	63
	64	if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) \|\|
	65	!(ecx & CPUID5_ECX_INTERRUPT_BREAK))
	66	return;
	67
	68	edx >>= MWAIT_SUBSTATE_SIZE;
	69	for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
	70	if (edx & MWAIT_SUBSTATE_MASK) {
	71	highest_cstate = i;
	72	highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
	73	}
	74	}
	75	power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) \|
	76	(highest_subcstate - 1);
	77
	78	for_each_online_cpu(i)
	79	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ON, &i);
	80
	81	#if defined(CONFIG_GENERIC_TIME) && defined(CONFIG_X86)
	82	switch (boot_cpu_data.x86_vendor) {
	83	case X86_VENDOR_AMD:
	84	case X86_VENDOR_INTEL:
	85	/*
	86	* AMD Fam10h TSC will tick in all
	87	* C/P/S0/S1 states when this bit is set.
	88	*/
	89	if (boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
	90	return;
	91
	92	/FALL THROUGH/
	93	default:
0dc698b9 VP	94	/* TSC could halt in idle */
0dc698b9 VP	95	tsc_detected_unstable = 1;
8e0af514 SL	96	}
	97	#endif
	98	}
	99
	100	static unsigned long cpu_weight[NR_CPUS];
	101	static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1};
	102	static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS);
	103	static void round_robin_cpu(unsigned int tsk_index)
	104	{
	105	struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
	106	cpumask_var_t tmp;
	107	int cpu;
f67538f8 AM	108	unsigned long min_weight = -1;
f67538f8 AM	109	unsigned long uninitialized_var(preferred_cpu);
8e0af514 SL	110
	111	if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
	112	return;
	113
	114	mutex_lock(&isolated_cpus_lock);
	115	cpumask_clear(tmp);
	116	for_each_cpu(cpu, pad_busy_cpus)
	117	cpumask_or(tmp, tmp, topology_thread_cpumask(cpu));
	118	cpumask_andnot(tmp, cpu_online_mask, tmp);
	119	/* avoid HT sibilings if possible */
	120	if (cpumask_empty(tmp))
	121	cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
	122	if (cpumask_empty(tmp)) {
	123	mutex_unlock(&isolated_cpus_lock);
	124	return;
	125	}
	126	for_each_cpu(cpu, tmp) {
	127	if (cpu_weight[cpu] < min_weight) {
	128	min_weight = cpu_weight[cpu];
	129	preferred_cpu = cpu;
	130	}
	131	}
	132
	133	if (tsk_in_cpu[tsk_index] != -1)
	134	cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
	135	tsk_in_cpu[tsk_index] = preferred_cpu;
	136	cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
	137	cpu_weight[preferred_cpu]++;
	138	mutex_unlock(&isolated_cpus_lock);
	139
	140	set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
	141	}
	142
	143	static void exit_round_robin(unsigned int tsk_index)
	144	{
	145	struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
	146	cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
	147	tsk_in_cpu[tsk_index] = -1;
	148	}
	149
	150	static unsigned int idle_pct = 5; /* percentage */
	151	static unsigned int round_robin_time = 10; /* second */
	152	static int power_saving_thread(void *data)
	153	{
	154	struct sched_param param = {.sched_priority = 1};
	155	int do_sleep;
	156	unsigned int tsk_index = (unsigned long)data;
	157	u64 last_jiffies = 0;
	158
	159	sched_setscheduler(current, SCHED_RR, &param);
	160
	161	while (!kthread_should_stop()) {
	162	int cpu;
	163	u64 expire_time;
	164
	165	try_to_freeze();
	166
	167	/* round robin to cpus */
	168	if (last_jiffies + round_robin_time * HZ < jiffies) {
	169	last_jiffies = jiffies;
	170	round_robin_cpu(tsk_index);
	171	}
	172
	173	do_sleep = 0;
174
8e0af514 SL	175	expire_time = jiffies + HZ * (100 - idle_pct) / 100;
	176
	177	while (!need_resched()) {
0dc698b9 VP	178	if (tsc_detected_unstable && !tsc_marked_unstable) {
	179	/* TSC could halt in idle, so notify users */
	180	mark_tsc_unstable("TSC halts in idle");
	181	tsc_marked_unstable = 1;
	182	}
8e0af514 SL	183	local_irq_disable();
	184	cpu = smp_processor_id();
	185	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
	186	&cpu);
	187	stop_critical_timings();
	188
	189	__monitor((void *)&current_thread_info()->flags, 0, 0);
	190	smp_mb();
	191	if (!need_resched())
	192	__mwait(power_saving_mwait_eax, 1);
	193
	194	start_critical_timings();
	195	clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
	196	&cpu);
	197	local_irq_enable();
	198
	199	if (jiffies > expire_time) {
	200	do_sleep = 1;
	201	break;
	202	}
	203	}
	204
8e0af514 SL	205	/*
	206	* current sched_rt has threshold for rt task running time.
	207	* When a rt task uses 95% CPU time, the rt thread will be
	208	* scheduled out for 5% CPU time to not starve other tasks. But
	209	* the mechanism only works when all CPUs have RT task running,
	210	* as if one CPU hasn't RT task, RT task from other CPUs will
	211	* borrow CPU time from this CPU and cause RT task use > 95%
3b8cb427	212	* CPU time. To make 'avoid starvation' work, takes a nap here.
8e0af514 SL	213	*/
	214	if (do_sleep)
	215	schedule_timeout_killable(HZ * idle_pct / 100);
	216	}
	217
	218	exit_round_robin(tsk_index);
	219	return 0;
	220	}
	221
	222	static struct task_struct *ps_tsks[NR_CPUS];
	223	static unsigned int ps_tsk_num;
	224	static int create_power_saving_task(void)
	225	{
3b8cb427 CG	226	int rc = -ENOMEM;
3b8cb427 CG	227
8e0af514 SL	228	ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
	229	(void *)(unsigned long)ps_tsk_num,
	230	"power_saving/%d", ps_tsk_num);
3b8cb427 CG	231	rc = IS_ERR(ps_tsks[ps_tsk_num]) ? PTR_ERR(ps_tsks[ps_tsk_num]) : 0;
3b8cb427 CG	232	if (!rc)
8e0af514	233	ps_tsk_num++;
3b8cb427 CG	234	else
	235	ps_tsks[ps_tsk_num] = NULL;
	236
	237	return rc;
8e0af514 SL	238	}
	239
	240	static void destroy_power_saving_task(void)
	241	{
	242	if (ps_tsk_num > 0) {
	243	ps_tsk_num--;
	244	kthread_stop(ps_tsks[ps_tsk_num]);
3b8cb427	245	ps_tsks[ps_tsk_num] = NULL;
8e0af514 SL	246	}
	247	}
	248
	249	static void set_power_saving_task_num(unsigned int num)
	250	{
	251	if (num > ps_tsk_num) {
	252	while (ps_tsk_num < num) {
	253	if (create_power_saving_task())
	254	return;
	255	}
	256	} else if (num < ps_tsk_num) {
	257	while (ps_tsk_num > num)
	258	destroy_power_saving_task();
	259	}
	260	}
	261
3b8cb427	262	static void acpi_pad_idle_cpus(unsigned int num_cpus)
8e0af514 SL	263	{
	264	get_online_cpus();
	265
	266	num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
	267	set_power_saving_task_num(num_cpus);
	268
	269	put_online_cpus();
8e0af514 SL	270	}
	271
	272	static uint32_t acpi_pad_idle_cpus_num(void)
	273	{
	274	return ps_tsk_num;
	275	}
	276
	277	static ssize_t acpi_pad_rrtime_store(struct device *dev,
	278	struct device_attribute attr, const char buf, size_t count)
	279	{
	280	unsigned long num;
	281	if (strict_strtoul(buf, 0, &num))
	282	return -EINVAL;
	283	if (num < 1 \|\| num >= 100)
	284	return -EINVAL;
	285	mutex_lock(&isolated_cpus_lock);
	286	round_robin_time = num;
	287	mutex_unlock(&isolated_cpus_lock);
	288	return count;
	289	}
	290
	291	static ssize_t acpi_pad_rrtime_show(struct device *dev,
	292	struct device_attribute attr, char buf)
	293	{
	294	return scnprintf(buf, PAGE_SIZE, "%d", round_robin_time);
	295	}
	296	static DEVICE_ATTR(rrtime, S_IRUGO\|S_IWUSR,
	297	acpi_pad_rrtime_show,
	298	acpi_pad_rrtime_store);
	299
	300	static ssize_t acpi_pad_idlepct_store(struct device *dev,
	301	struct device_attribute attr, const char buf, size_t count)
	302	{
	303	unsigned long num;
	304	if (strict_strtoul(buf, 0, &num))
	305	return -EINVAL;
	306	if (num < 1 \|\| num >= 100)
	307	return -EINVAL;
	308	mutex_lock(&isolated_cpus_lock);
	309	idle_pct = num;
	310	mutex_unlock(&isolated_cpus_lock);
	311	return count;
	312	}
	313
	314	static ssize_t acpi_pad_idlepct_show(struct device *dev,
	315	struct device_attribute attr, char buf)
	316	{
	317	return scnprintf(buf, PAGE_SIZE, "%d", idle_pct);
	318	}
	319	static DEVICE_ATTR(idlepct, S_IRUGO\|S_IWUSR,
	320	acpi_pad_idlepct_show,
	321	acpi_pad_idlepct_store);
	322
	323	static ssize_t acpi_pad_idlecpus_store(struct device *dev,
	324	struct device_attribute attr, const char buf, size_t count)
	325	{
	326	unsigned long num;
	327	if (strict_strtoul(buf, 0, &num))
	328	return -EINVAL;
	329	mutex_lock(&isolated_cpus_lock);
	330	acpi_pad_idle_cpus(num);
	331	mutex_unlock(&isolated_cpus_lock);
	332	return count;
	333	}
334
335	static ssize_t acpi_pad_idlecpus_show(struct device *dev,
336	struct device_attribute attr, char buf)
337	{
338	return cpumask_scnprintf(buf, PAGE_SIZE,
339	to_cpumask(pad_busy_cpus_bits));
340	}
341	static DEVICE_ATTR(idlecpus, S_IRUGO\|S_IWUSR,
342	acpi_pad_idlecpus_show,
343	acpi_pad_idlecpus_store);
344
345	static int acpi_pad_add_sysfs(struct acpi_device *device)
346	{
347	int result;
348
349	result = device_create_file(&device->dev, &dev_attr_idlecpus);
350	if (result)
351	return -ENODEV;
352	result = device_create_file(&device->dev, &dev_attr_idlepct);
353	if (result) {
354	device_remove_file(&device->dev, &dev_attr_idlecpus);
355	return -ENODEV;
356	}
357	result = device_create_file(&device->dev, &dev_attr_rrtime);
358	if (result) {
359	device_remove_file(&device->dev, &dev_attr_idlecpus);
360	device_remove_file(&device->dev, &dev_attr_idlepct);
361	return -ENODEV;
362	}
363	return 0;
364	}
365
366	static void acpi_pad_remove_sysfs(struct acpi_device *device)
367	{
368	device_remove_file(&device->dev, &dev_attr_idlecpus);
369	device_remove_file(&device->dev, &dev_attr_idlepct);
370	device_remove_file(&device->dev, &dev_attr_rrtime);
371	}
372
373	/* Query firmware how many CPUs should be idle */
374	static int acpi_pad_pur(acpi_handle handle, int *num_cpus)
375	{
376	struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
8e0af514 SL	377	union acpi_object *package;
	378	int rev, num, ret = -EINVAL;
	379
3b8cb427	380	if (ACPI_FAILURE(acpi_evaluate_object(handle, "_PUR", NULL, &buffer)))
8e0af514	381	return -EINVAL;
3b8cb427 CG	382
	383	if (!buffer.length \|\| !buffer.pointer)
	384	return -EINVAL;
	385
8e0af514 SL	386	package = buffer.pointer;
	387	if (package->type != ACPI_TYPE_PACKAGE \|\| package->package.count != 2)
	388	goto out;
	389	rev = package->package.elements[0].integer.value;
	390	num = package->package.elements[1].integer.value;
3b8cb427	391	if (rev != 1 \|\| num < 0)
8e0af514 SL	392	goto out;
	393	*num_cpus = num;
	394	ret = 0;
	395	out:
	396	kfree(buffer.pointer);
	397	return ret;
	398	}
	399
	400	/* Notify firmware how many CPUs are idle */
	401	static void acpi_pad_ost(acpi_handle handle, int stat,
	402	uint32_t idle_cpus)
	403	{
	404	union acpi_object params[3] = {
	405	{.type = ACPI_TYPE_INTEGER,},
	406	{.type = ACPI_TYPE_INTEGER,},
	407	{.type = ACPI_TYPE_BUFFER,},
	408	};
	409	struct acpi_object_list arg_list = {3, params};
	410
	411	params[0].integer.value = ACPI_PROCESSOR_AGGREGATOR_NOTIFY;
	412	params[1].integer.value = stat;
	413	params[2].buffer.length = 4;
	414	params[2].buffer.pointer = (void *)&idle_cpus;
	415	acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
	416	}
	417
	418	static void acpi_pad_handle_notify(acpi_handle handle)
	419	{
3b8cb427	420	int num_cpus;
8e0af514 SL	421	uint32_t idle_cpus;
	422
	423	mutex_lock(&isolated_cpus_lock);
	424	if (acpi_pad_pur(handle, &num_cpus)) {
	425	mutex_unlock(&isolated_cpus_lock);
	426	return;
	427	}
3b8cb427	428	acpi_pad_idle_cpus(num_cpus);
8e0af514	429	idle_cpus = acpi_pad_idle_cpus_num();
3b8cb427	430	acpi_pad_ost(handle, 0, idle_cpus);
8e0af514 SL	431	mutex_unlock(&isolated_cpus_lock);
	432	}
	433
	434	static void acpi_pad_notify(acpi_handle handle, u32 event,
	435	void *data)
	436	{
	437	struct acpi_device *device = data;
	438
	439	switch (event) {
	440	case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
	441	acpi_pad_handle_notify(handle);
	442	acpi_bus_generate_proc_event(device, event, 0);
	443	acpi_bus_generate_netlink_event(device->pnp.device_class,
	444	dev_name(&device->dev), event, 0);
	445	break;
	446	default:
	447	printk(KERN_WARNING"Unsupported event [0x%x]\n", event);
	448	break;
	449	}
	450	}
	451
	452	static int acpi_pad_add(struct acpi_device *device)
	453	{
	454	acpi_status status;
	455
	456	strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
	457	strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
	458
	459	if (acpi_pad_add_sysfs(device))
	460	return -ENODEV;
	461
	462	status = acpi_install_notify_handler(device->handle,
	463	ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
	464	if (ACPI_FAILURE(status)) {
	465	acpi_pad_remove_sysfs(device);
	466	return -ENODEV;
	467	}
	468
	469	return 0;
	470	}
	471
	472	static int acpi_pad_remove(struct acpi_device *device,
	473	int type)
	474	{
	475	mutex_lock(&isolated_cpus_lock);
	476	acpi_pad_idle_cpus(0);
	477	mutex_unlock(&isolated_cpus_lock);
	478
	479	acpi_remove_notify_handler(device->handle,
	480	ACPI_DEVICE_NOTIFY, acpi_pad_notify);
	481	acpi_pad_remove_sysfs(device);
	482	return 0;
	483	}
	484
	485	static const struct acpi_device_id pad_device_ids[] = {
	486	{"ACPI000C", 0},
	487	{"", 0},
	488	};
	489	MODULE_DEVICE_TABLE(acpi, pad_device_ids);
	490
	491	static struct acpi_driver acpi_pad_driver = {
	492	.name = "processor_aggregator",
	493	.class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
	494	.ids = pad_device_ids,
495	.ops = {
496	.add = acpi_pad_add,
497	.remove = acpi_pad_remove,
498	},
499	};
500
501	static int __init acpi_pad_init(void)
502	{
503	power_saving_mwait_init();
504	if (power_saving_mwait_eax == 0)
505	return -EINVAL;
506
507	return acpi_bus_register_driver(&acpi_pad_driver);
508	}
509
510	static void __exit acpi_pad_exit(void)
511	{
512	acpi_bus_unregister_driver(&acpi_pad_driver);
513	}
514
515	module_init(acpi_pad_init);
516	module_exit(acpi_pad_exit);
517	MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
518	MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
519	MODULE_LICENSE("GPL");