drivers/acpi/processor_core.c - maze/linux - Git at Google

 /*
  * Copyright (C) 2005 Intel Corporation
  * Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
  *
  *	Alex Chiang <achiang@hp.com>
  *	- Unified x86/ia64 implementations
  *	Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
  *	- Added _PDC for platforms with Intel CPUs
  */
 #include <linux/dmi.h>

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

 #include "internal.h"

 #define PREFIX			"ACPI: "
 #define _COMPONENT		ACPI_PROCESSOR_COMPONENT
 ACPI_MODULE_NAME("processor_core");

 static int set_no_mwait(const struct dmi_system_id *id)
 {
 	printk(KERN_NOTICE PREFIX "%s detected - "
 		"disabling mwait for CPU C-states\n", id->ident);
 	idle_nomwait = 1;
 	return 0;
 }

 static struct dmi_system_id __cpuinitdata processor_idle_dmi_table[] = {
 	{
 	set_no_mwait, "IFL91 board", {
 	DMI_MATCH(DMI_BIOS_VENDOR, "COMPAL"),
 	DMI_MATCH(DMI_SYS_VENDOR, "ZEPTO"),
 	DMI_MATCH(DMI_PRODUCT_VERSION, "3215W"),
 	DMI_MATCH(DMI_BOARD_NAME, "IFL91") }, NULL},
 	{
 	set_no_mwait, "Extensa 5220", {
 	DMI_MATCH(DMI_BIOS_VENDOR, "Phoenix Technologies LTD"),
 	DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
 	DMI_MATCH(DMI_PRODUCT_VERSION, "0100"),
 	DMI_MATCH(DMI_BOARD_NAME, "Columbia") }, NULL},
 	{},
 };

 #ifdef CONFIG_SMP
 static struct acpi_table_madt *madt;

 static int map_lapic_id(struct acpi_subtable_header *entry,
 		 u32 acpi_id, int *apic_id)
 {
 	struct acpi_madt_local_apic *lapic =
 		(struct acpi_madt_local_apic *)entry;
 	if ((lapic->lapic_flags & ACPI_MADT_ENABLED) &&
 	    lapic->processor_id == acpi_id) {
 		*apic_id = lapic->id;
 		return 1;
 	}
 	return 0;
 }

 static int map_x2apic_id(struct acpi_subtable_header *entry,
 			 int device_declaration, u32 acpi_id, int *apic_id)
 {
 	struct acpi_madt_local_x2apic *apic =
 		(struct acpi_madt_local_x2apic *)entry;
 	u32 tmp = apic->local_apic_id;

 	/* Only check enabled APICs*/
 	if (!(apic->lapic_flags & ACPI_MADT_ENABLED))
 		return 0;

 	/* Device statement declaration type */
 	if (device_declaration) {
 		if (apic->uid == acpi_id)
 			goto found;
 	}

 	return 0;
 found:
 	*apic_id = tmp;
 	return 1;
 }

 static int map_lsapic_id(struct acpi_subtable_header *entry,
 		int device_declaration, u32 acpi_id, int *apic_id)
 {
 	struct acpi_madt_local_sapic *lsapic =
 		(struct acpi_madt_local_sapic *)entry;
 	u32 tmp = (lsapic->id << 8) | lsapic->eid;

 	/* Only check enabled APICs*/
 	if (!(lsapic->lapic_flags & ACPI_MADT_ENABLED))
 		return 0;

 	/* Device statement declaration type */
 	if (device_declaration) {
 		if (entry->length < 16)
 			printk(KERN_ERR PREFIX
 			    "Invalid LSAPIC with Device type processor (SAPIC ID %#x)\n",
 			    tmp);
 		else if (lsapic->uid == acpi_id)
 			goto found;
 	/* Processor statement declaration type */
 	} else if (lsapic->processor_id == acpi_id)
 		goto found;

 	return 0;
 found:
 	*apic_id = tmp;
 	return 1;
 }

 static int map_madt_entry(int type, u32 acpi_id)
 {
 	unsigned long madt_end, entry;
 	int apic_id = -1;

 	if (!madt)
 		return apic_id;

 	entry = (unsigned long)madt;
 	madt_end = entry + madt->header.length;

 	/* Parse all entries looking for a match. */

 	entry += sizeof(struct acpi_table_madt);
 	while (entry + sizeof(struct acpi_subtable_header) < madt_end) {
 		struct acpi_subtable_header *header =
 			(struct acpi_subtable_header *)entry;
 		if (header->type == ACPI_MADT_TYPE_LOCAL_APIC) {
 			if (map_lapic_id(header, acpi_id, &apic_id))
 				break;
 		} else if (header->type == ACPI_MADT_TYPE_LOCAL_X2APIC) {
 			if (map_x2apic_id(header, type, acpi_id, &apic_id))
 				break;
 		} else if (header->type == ACPI_MADT_TYPE_LOCAL_SAPIC) {
 			if (map_lsapic_id(header, type, acpi_id, &apic_id))
 				break;
 		}
 		entry += header->length;
 	}
 	return apic_id;
 }

 static int map_mat_entry(acpi_handle handle, int type, u32 acpi_id)
 {
 	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 	union acpi_object *obj;
 	struct acpi_subtable_header *header;
 	int apic_id = -1;

 	if (ACPI_FAILURE(acpi_evaluate_object(handle, "_MAT", NULL, &buffer)))
 		goto exit;

 	if (!buffer.length || !buffer.pointer)
 		goto exit;

 	obj = buffer.pointer;
 	if (obj->type != ACPI_TYPE_BUFFER ||
 	    obj->buffer.length < sizeof(struct acpi_subtable_header)) {
 		goto exit;
 	}

 	header = (struct acpi_subtable_header *)obj->buffer.pointer;
 	if (header->type == ACPI_MADT_TYPE_LOCAL_APIC) {
 		map_lapic_id(header, acpi_id, &apic_id);
 	} else if (header->type == ACPI_MADT_TYPE_LOCAL_SAPIC) {
 		map_lsapic_id(header, type, acpi_id, &apic_id);
 	}

 exit:
 	if (buffer.pointer)
 		kfree(buffer.pointer);
 	return apic_id;
 }

 int acpi_get_cpuid(acpi_handle handle, int type, u32 acpi_id)
 {
 	int i;
 	int apic_id = -1;

 	apic_id = map_mat_entry(handle, type, acpi_id);
 	if (apic_id == -1)
 		apic_id = map_madt_entry(type, acpi_id);
 	if (apic_id == -1)
 		return apic_id;

 	for_each_possible_cpu(i) {
 		if (cpu_physical_id(i) == apic_id)
 			return i;
 	}
 	return -1;
 }
 EXPORT_SYMBOL_GPL(acpi_get_cpuid);
 #endif

 static bool processor_physically_present(acpi_handle handle)
 {
 	int cpuid, type;
 	u32 acpi_id;
 	acpi_status status;
 	acpi_object_type acpi_type;
 	unsigned long long tmp;
 	union acpi_object object = { 0 };
 	struct acpi_buffer buffer = { sizeof(union acpi_object), &object };

 	status = acpi_get_type(handle, &acpi_type);
 	if (ACPI_FAILURE(status))
 		return false;

 	switch (acpi_type) {
 	case ACPI_TYPE_PROCESSOR:
 		status = acpi_evaluate_object(handle, NULL, NULL, &buffer);
 		if (ACPI_FAILURE(status))
 			return false;
 		acpi_id = object.processor.proc_id;
 		break;
 	case ACPI_TYPE_DEVICE:
 		status = acpi_evaluate_integer(handle, "_UID", NULL, &tmp);
 		if (ACPI_FAILURE(status))
 			return false;
 		acpi_id = tmp;
 		break;
 	default:
 		return false;
 	}

 	type = (acpi_type == ACPI_TYPE_DEVICE) ? 1 : 0;
 	cpuid = acpi_get_cpuid(handle, type, acpi_id);

 	if (cpuid == -1)
 		return false;

 	return true;
 }

 static void acpi_set_pdc_bits(u32 *buf)
 {
 	buf[0] = ACPI_PDC_REVISION_ID;
 	buf[1] = 1;

 	/* Enable coordination with firmware's _TSD info */
 	buf[2] = ACPI_PDC_SMP_T_SWCOORD;

 	/* Twiddle arch-specific bits needed for _PDC */
 	arch_acpi_set_pdc_bits(buf);
 }

 static struct acpi_object_list *acpi_processor_alloc_pdc(void)
 {
 	struct acpi_object_list *obj_list;
 	union acpi_object *obj;
 	u32 *buf;

 	/* allocate and initialize pdc. It will be used later. */
 	obj_list = kmalloc(sizeof(struct acpi_object_list), GFP_KERNEL);
 	if (!obj_list) {
 		printk(KERN_ERR "Memory allocation error\n");
 		return NULL;
 	}

 	obj = kmalloc(sizeof(union acpi_object), GFP_KERNEL);
 	if (!obj) {
 		printk(KERN_ERR "Memory allocation error\n");
 		kfree(obj_list);
 		return NULL;
 	}

 	buf = kmalloc(12, GFP_KERNEL);
 	if (!buf) {
 		printk(KERN_ERR "Memory allocation error\n");
 		kfree(obj);
 		kfree(obj_list);
 		return NULL;
 	}

 	acpi_set_pdc_bits(buf);

 	obj->type = ACPI_TYPE_BUFFER;
 	obj->buffer.length = 12;
 	obj->buffer.pointer = (u8 *) buf;
 	obj_list->count = 1;
 	obj_list->pointer = obj;

 	return obj_list;
 }

 /*
  * _PDC is required for a BIOS-OS handshake for most of the newer
  * ACPI processor features.
  */
 static int
 acpi_processor_eval_pdc(acpi_handle handle, struct acpi_object_list *pdc_in)
 {
 	acpi_status status = AE_OK;

 	if (idle_nomwait) {
 		/*
 		 * If mwait is disabled for CPU C-states, the C2C3_FFH access
 		 * mode will be disabled in the parameter of _PDC object.
 		 * Of course C1_FFH access mode will also be disabled.
 		 */
 		union acpi_object *obj;
 		u32 *buffer = NULL;

 		obj = pdc_in->pointer;
 		buffer = (u32 *)(obj->buffer.pointer);
 		buffer[2] &= ~(ACPI_PDC_C_C2C3_FFH | ACPI_PDC_C_C1_FFH);

 	}
 	status = acpi_evaluate_object(handle, "_PDC", pdc_in, NULL);

 	if (ACPI_FAILURE(status))
 		ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 		    "Could not evaluate _PDC, using legacy perf. control.\n"));

 	return status;
 }

 static int early_pdc_done;

 void acpi_processor_set_pdc(acpi_handle handle)
 {
 	struct acpi_object_list *obj_list;

 	if (arch_has_acpi_pdc() == false)
 		return;

 	if (early_pdc_done)
 		return;

 	obj_list = acpi_processor_alloc_pdc();
 	if (!obj_list)
 		return;

 	acpi_processor_eval_pdc(handle, obj_list);

 	kfree(obj_list->pointer->buffer.pointer);
 	kfree(obj_list->pointer);
 	kfree(obj_list);
 }
 EXPORT_SYMBOL_GPL(acpi_processor_set_pdc);

 static int early_pdc_optin;
 static int set_early_pdc_optin(const struct dmi_system_id *id)
 {
 	early_pdc_optin = 1;
 	return 0;
 }

 static int param_early_pdc_optin(char *s)
 {
 	early_pdc_optin = 1;
 	return 1;
 }
 __setup("acpi_early_pdc_eval", param_early_pdc_optin);

 static struct dmi_system_id __cpuinitdata early_pdc_optin_table[] = {
 	{
 	set_early_pdc_optin, "HP Envy", {
 	DMI_MATCH(DMI_BIOS_VENDOR, "Hewlett-Packard"),
 	DMI_MATCH(DMI_PRODUCT_NAME, "HP Envy") }, NULL},
 	{
 	set_early_pdc_optin, "HP Pavilion dv6", {
 	DMI_MATCH(DMI_BIOS_VENDOR, "Hewlett-Packard"),
 	DMI_MATCH(DMI_PRODUCT_NAME, "HP Pavilion dv6") }, NULL},
 	{
 	set_early_pdc_optin, "HP Pavilion dv7", {
 	DMI_MATCH(DMI_BIOS_VENDOR, "Hewlett-Packard"),
 	DMI_MATCH(DMI_PRODUCT_NAME, "HP Pavilion dv7") }, NULL},
 	{},
 };

 static acpi_status
 early_init_pdc(acpi_handle handle, u32 lvl, void *context, void **rv)
 {
 	if (processor_physically_present(handle) == false)
 		return AE_OK;

 	acpi_processor_set_pdc(handle);
 	return AE_OK;
 }

 void __init acpi_early_processor_set_pdc(void)
 {

 #ifdef CONFIG_SMP
 	if (ACPI_FAILURE(acpi_get_table(ACPI_SIG_MADT, 0,
 				(struct acpi_table_header **)&madt)))
 		madt = NULL;
 #endif

 	/*
 	 * Check whether the system is DMI table. If yes, OSPM
 	 * should not use mwait for CPU-states.
 	 */
 	dmi_check_system(processor_idle_dmi_table);

 	/*
 	 * Allow systems to opt-in to early _PDC evaluation.
 	 */
 	dmi_check_system(early_pdc_optin_table);
 	if (!early_pdc_optin)
 		return;

 	acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,
 			    ACPI_UINT32_MAX,
 			    early_init_pdc, NULL, NULL, NULL);

 	early_pdc_done = 1;
 }
	/*
	* Copyright (C) 2005 Intel Corporation
	* Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
	*
	* Alex Chiang <achiang@hp.com>
	* - Unified x86/ia64 implementations
	* Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
	* - Added _PDC for platforms with Intel CPUs
	*/
	#include <linux/dmi.h>

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

	#include "internal.h"

	#define PREFIX "ACPI: "
	#define _COMPONENT ACPI_PROCESSOR_COMPONENT
	ACPI_MODULE_NAME("processor_core");

	static int set_no_mwait(const struct dmi_system_id *id)
	{
	printk(KERN_NOTICE PREFIX "%s detected - "
	"disabling mwait for CPU C-states\n", id->ident);
	idle_nomwait = 1;
	return 0;
	}

	static struct dmi_system_id __cpuinitdata processor_idle_dmi_table[] = {
	{
	set_no_mwait, "IFL91 board", {
	DMI_MATCH(DMI_BIOS_VENDOR, "COMPAL"),
	DMI_MATCH(DMI_SYS_VENDOR, "ZEPTO"),
	DMI_MATCH(DMI_PRODUCT_VERSION, "3215W"),
	DMI_MATCH(DMI_BOARD_NAME, "IFL91") }, NULL},
	{
	set_no_mwait, "Extensa 5220", {
	DMI_MATCH(DMI_BIOS_VENDOR, "Phoenix Technologies LTD"),
	DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
	DMI_MATCH(DMI_PRODUCT_VERSION, "0100"),
	DMI_MATCH(DMI_BOARD_NAME, "Columbia") }, NULL},
	{},
	};

	#ifdef CONFIG_SMP
	static struct acpi_table_madt *madt;

	static int map_lapic_id(struct acpi_subtable_header *entry,
	u32 acpi_id, int *apic_id)
	{
	struct acpi_madt_local_apic *lapic =
	(struct acpi_madt_local_apic *)entry;
	if ((lapic->lapic_flags & ACPI_MADT_ENABLED) &&
	lapic->processor_id == acpi_id) {
	*apic_id = lapic->id;
	return 1;
	}
	return 0;
	}

	static int map_x2apic_id(struct acpi_subtable_header *entry,
	int device_declaration, u32 acpi_id, int *apic_id)
	{
	struct acpi_madt_local_x2apic *apic =
	(struct acpi_madt_local_x2apic *)entry;
	u32 tmp = apic->local_apic_id;

	/* Only check enabled APICs*/
	if (!(apic->lapic_flags & ACPI_MADT_ENABLED))
	return 0;

	/* Device statement declaration type */
	if (device_declaration) {
	if (apic->uid == acpi_id)
	goto found;
	}

	return 0;
	found:
	*apic_id = tmp;
	return 1;
	}

	static int map_lsapic_id(struct acpi_subtable_header *entry,
	int device_declaration, u32 acpi_id, int *apic_id)
	{
	struct acpi_madt_local_sapic *lsapic =
	(struct acpi_madt_local_sapic *)entry;
	u32 tmp = (lsapic->id << 8) \| lsapic->eid;

	/* Only check enabled APICs*/
	if (!(lsapic->lapic_flags & ACPI_MADT_ENABLED))
	return 0;

	/* Device statement declaration type */
	if (device_declaration) {
	if (entry->length < 16)
	printk(KERN_ERR PREFIX
	"Invalid LSAPIC with Device type processor (SAPIC ID %#x)\n",
	tmp);
	else if (lsapic->uid == acpi_id)
	goto found;
	/* Processor statement declaration type */
	} else if (lsapic->processor_id == acpi_id)
	goto found;

	return 0;
	found:
	*apic_id = tmp;
	return 1;
	}

	static int map_madt_entry(int type, u32 acpi_id)
	{
	unsigned long madt_end, entry;
	int apic_id = -1;

	if (!madt)
	return apic_id;

	entry = (unsigned long)madt;
	madt_end = entry + madt->header.length;

	/* Parse all entries looking for a match. */

	entry += sizeof(struct acpi_table_madt);
	while (entry + sizeof(struct acpi_subtable_header) < madt_end) {
	struct acpi_subtable_header *header =
	(struct acpi_subtable_header *)entry;
	if (header->type == ACPI_MADT_TYPE_LOCAL_APIC) {
	if (map_lapic_id(header, acpi_id, &apic_id))
	break;
	} else if (header->type == ACPI_MADT_TYPE_LOCAL_X2APIC) {
	if (map_x2apic_id(header, type, acpi_id, &apic_id))
	break;
	} else if (header->type == ACPI_MADT_TYPE_LOCAL_SAPIC) {
	if (map_lsapic_id(header, type, acpi_id, &apic_id))
	break;
	}
	entry += header->length;
	}
	return apic_id;
	}

	static int map_mat_entry(acpi_handle handle, int type, u32 acpi_id)
	{
	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
	union acpi_object *obj;
	struct acpi_subtable_header *header;
	int apic_id = -1;

	if (ACPI_FAILURE(acpi_evaluate_object(handle, "_MAT", NULL, &buffer)))
	goto exit;

	if (!buffer.length \|\| !buffer.pointer)
	goto exit;

	obj = buffer.pointer;
	if (obj->type != ACPI_TYPE_BUFFER \|\|
	obj->buffer.length < sizeof(struct acpi_subtable_header)) {
	goto exit;
	}

	header = (struct acpi_subtable_header *)obj->buffer.pointer;
	if (header->type == ACPI_MADT_TYPE_LOCAL_APIC) {
	map_lapic_id(header, acpi_id, &apic_id);
	} else if (header->type == ACPI_MADT_TYPE_LOCAL_SAPIC) {
	map_lsapic_id(header, type, acpi_id, &apic_id);
	}

	exit:
	if (buffer.pointer)
	kfree(buffer.pointer);
	return apic_id;
	}

	int acpi_get_cpuid(acpi_handle handle, int type, u32 acpi_id)
	{
	int i;
	int apic_id = -1;

	apic_id = map_mat_entry(handle, type, acpi_id);
	if (apic_id == -1)
	apic_id = map_madt_entry(type, acpi_id);
	if (apic_id == -1)
	return apic_id;

	for_each_possible_cpu(i) {
	if (cpu_physical_id(i) == apic_id)
	return i;
	}
	return -1;
	}
	EXPORT_SYMBOL_GPL(acpi_get_cpuid);
	#endif

	static bool processor_physically_present(acpi_handle handle)
	{
	int cpuid, type;
	u32 acpi_id;
	acpi_status status;
	acpi_object_type acpi_type;
	unsigned long long tmp;
	union acpi_object object = { 0 };
	struct acpi_buffer buffer = { sizeof(union acpi_object), &object };

	status = acpi_get_type(handle, &acpi_type);
	if (ACPI_FAILURE(status))
	return false;

	switch (acpi_type) {
	case ACPI_TYPE_PROCESSOR:
	status = acpi_evaluate_object(handle, NULL, NULL, &buffer);
	if (ACPI_FAILURE(status))
	return false;
	acpi_id = object.processor.proc_id;
	break;
	case ACPI_TYPE_DEVICE:
	status = acpi_evaluate_integer(handle, "_UID", NULL, &tmp);
	if (ACPI_FAILURE(status))
	return false;
	acpi_id = tmp;
	break;
	default:
	return false;
	}

	type = (acpi_type == ACPI_TYPE_DEVICE) ? 1 : 0;
	cpuid = acpi_get_cpuid(handle, type, acpi_id);

	if (cpuid == -1)
	return false;

	return true;
	}

	static void acpi_set_pdc_bits(u32 *buf)
	{
	buf[0] = ACPI_PDC_REVISION_ID;
	buf[1] = 1;

	/* Enable coordination with firmware's _TSD info */
	buf[2] = ACPI_PDC_SMP_T_SWCOORD;

	/* Twiddle arch-specific bits needed for _PDC */
	arch_acpi_set_pdc_bits(buf);
	}

	static struct acpi_object_list *acpi_processor_alloc_pdc(void)
	{
	struct acpi_object_list *obj_list;
	union acpi_object *obj;
	u32 *buf;

	/* allocate and initialize pdc. It will be used later. */
	obj_list = kmalloc(sizeof(struct acpi_object_list), GFP_KERNEL);
	if (!obj_list) {
	printk(KERN_ERR "Memory allocation error\n");
	return NULL;
	}

	obj = kmalloc(sizeof(union acpi_object), GFP_KERNEL);
	if (!obj) {
	printk(KERN_ERR "Memory allocation error\n");
	kfree(obj_list);
	return NULL;
	}

	buf = kmalloc(12, GFP_KERNEL);
	if (!buf) {
	printk(KERN_ERR "Memory allocation error\n");
	kfree(obj);
	kfree(obj_list);
	return NULL;
	}

	acpi_set_pdc_bits(buf);

	obj->type = ACPI_TYPE_BUFFER;
	obj->buffer.length = 12;
	obj->buffer.pointer = (u8 *) buf;
	obj_list->count = 1;
	obj_list->pointer = obj;

	return obj_list;
	}

	/*
	* _PDC is required for a BIOS-OS handshake for most of the newer
	* ACPI processor features.
	*/
	static int
	acpi_processor_eval_pdc(acpi_handle handle, struct acpi_object_list *pdc_in)
	{
	acpi_status status = AE_OK;

	if (idle_nomwait) {
	/*
	* If mwait is disabled for CPU C-states, the C2C3_FFH access
	* mode will be disabled in the parameter of _PDC object.
	* Of course C1_FFH access mode will also be disabled.
	*/
	union acpi_object *obj;
	u32 *buffer = NULL;

	obj = pdc_in->pointer;
	buffer = (u32 *)(obj->buffer.pointer);
	buffer[2] &= ~(ACPI_PDC_C_C2C3_FFH \| ACPI_PDC_C_C1_FFH);

	}
	status = acpi_evaluate_object(handle, "_PDC", pdc_in, NULL);

	if (ACPI_FAILURE(status))
	ACPI_DEBUG_PRINT((ACPI_DB_INFO,
	"Could not evaluate _PDC, using legacy perf. control.\n"));

	return status;
	}

	static int early_pdc_done;

	void acpi_processor_set_pdc(acpi_handle handle)
	{
	struct acpi_object_list *obj_list;

	if (arch_has_acpi_pdc() == false)
	return;

	if (early_pdc_done)
	return;

	obj_list = acpi_processor_alloc_pdc();
	if (!obj_list)
	return;

	acpi_processor_eval_pdc(handle, obj_list);

	kfree(obj_list->pointer->buffer.pointer);
	kfree(obj_list->pointer);
	kfree(obj_list);
	}
	EXPORT_SYMBOL_GPL(acpi_processor_set_pdc);

	static int early_pdc_optin;
	static int set_early_pdc_optin(const struct dmi_system_id *id)
	{
	early_pdc_optin = 1;
	return 0;
	}

	static int param_early_pdc_optin(char *s)
	{
	early_pdc_optin = 1;
	return 1;
	}
	__setup("acpi_early_pdc_eval", param_early_pdc_optin);

	static struct dmi_system_id __cpuinitdata early_pdc_optin_table[] = {
	{
	set_early_pdc_optin, "HP Envy", {
	DMI_MATCH(DMI_BIOS_VENDOR, "Hewlett-Packard"),
	DMI_MATCH(DMI_PRODUCT_NAME, "HP Envy") }, NULL},
	{
	set_early_pdc_optin, "HP Pavilion dv6", {
	DMI_MATCH(DMI_BIOS_VENDOR, "Hewlett-Packard"),
	DMI_MATCH(DMI_PRODUCT_NAME, "HP Pavilion dv6") }, NULL},
	{
	set_early_pdc_optin, "HP Pavilion dv7", {
	DMI_MATCH(DMI_BIOS_VENDOR, "Hewlett-Packard"),
	DMI_MATCH(DMI_PRODUCT_NAME, "HP Pavilion dv7") }, NULL},
	{},
	};

	static acpi_status
	early_init_pdc(acpi_handle handle, u32 lvl, void context, void *rv)
	{
	if (processor_physically_present(handle) == false)
	return AE_OK;

	acpi_processor_set_pdc(handle);
	return AE_OK;
	}

	void __init acpi_early_processor_set_pdc(void)
	{

	#ifdef CONFIG_SMP
	if (ACPI_FAILURE(acpi_get_table(ACPI_SIG_MADT, 0,
	(struct acpi_table_header **)&madt)))
	madt = NULL;
	#endif

	/*
	* Check whether the system is DMI table. If yes, OSPM
	* should not use mwait for CPU-states.
	*/
	dmi_check_system(processor_idle_dmi_table);

	/*
	* Allow systems to opt-in to early _PDC evaluation.
	*/
	dmi_check_system(early_pdc_optin_table);
	if (!early_pdc_optin)
	return;

	acpi_walk_namespace(ACPI_TYPE_PROCESSOR, ACPI_ROOT_OBJECT,
	ACPI_UINT32_MAX,
	early_init_pdc, NULL, NULL, NULL);

	early_pdc_done = 1;
	}