[linux-2.6-block.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 <acpi/acpi_bus.h>
#include <acpi/acpi_drivers.h>

#define ACPI_PROCESSOR_AGGREGATOR_CLASS	"processor_aggregator"
#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 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, so notify users */
		mark_tsc_unstable("TSC halts in idle");
	}
#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;

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

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

		while (!need_resched()) {
			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_thread_info()->status |= TS_POLLING;

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