drivers/cpufreq/speedstep-ich.c - linux - Git at Google

 /*
  * (C) 2001  Dave Jones, Arjan van de ven.
  * (C) 2002 - 2003  Dominik Brodowski <linux@brodo.de>
  *
  *  Licensed under the terms of the GNU GPL License version 2.
  *  Based upon reverse engineered information, and on Intel documentation
  *  for chipsets ICH2-M and ICH3-M.
  *
  *  Many thanks to Ducrot Bruno for finding and fixing the last
  *  "missing link" for ICH2-M/ICH3-M support, and to Thomas Winkler
  *  for extensive testing.
  *
  *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
  */


 /*********************************************************************
  *                        SPEEDSTEP - DEFINITIONS                    *
  *********************************************************************/

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/cpufreq.h>
 #include <linux/pci.h>
 #include <linux/sched.h>

 #include <asm/cpu_device_id.h>

 #include "speedstep-lib.h"


 /* speedstep_chipset:
  *   It is necessary to know which chipset is used. As accesses to
  * this device occur at various places in this module, we need a
  * static struct pci_dev * pointing to that device.
  */
 static struct pci_dev *speedstep_chipset_dev;


 /* speedstep_processor
  */
 static enum speedstep_processor speedstep_processor;

 static u32 pmbase;

 /*
  *   There are only two frequency states for each processor. Values
  * are in kHz for the time being.
  */
 static struct cpufreq_frequency_table speedstep_freqs[] = {
 	{SPEEDSTEP_HIGH,	0},
 	{SPEEDSTEP_LOW,		0},
 	{0,			CPUFREQ_TABLE_END},
 };


 /**
  * speedstep_find_register - read the PMBASE address
  *
  * Returns: -ENODEV if no register could be found
  */
 static int speedstep_find_register(void)
 {
 	if (!speedstep_chipset_dev)
 		return -ENODEV;

 	/* get PMBASE */
 	pci_read_config_dword(speedstep_chipset_dev, 0x40, &pmbase);
 	if (!(pmbase & 0x01)) {
 		printk(KERN_ERR "speedstep-ich: could not find speedstep register\n");
 		return -ENODEV;
 	}

 	pmbase &= 0xFFFFFFFE;
 	if (!pmbase) {
 		printk(KERN_ERR "speedstep-ich: could not find speedstep register\n");
 		return -ENODEV;
 	}

 	pr_debug("pmbase is 0x%x\n", pmbase);
 	return 0;
 }

 /**
  * speedstep_set_state - set the SpeedStep state
  * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
  *
  *   Tries to change the SpeedStep state.  Can be called from
  *   smp_call_function_single.
  */
 static void speedstep_set_state(unsigned int state)
 {
 	u8 pm2_blk;
 	u8 value;
 	unsigned long flags;

 	if (state > 0x1)
 		return;

 	/* Disable IRQs */
 	local_irq_save(flags);

 	/* read state */
 	value = inb(pmbase + 0x50);

 	pr_debug("read at pmbase 0x%x + 0x50 returned 0x%x\n", pmbase, value);

 	/* write new state */
 	value &= 0xFE;
 	value |= state;

 	pr_debug("writing 0x%x to pmbase 0x%x + 0x50\n", value, pmbase);

 	/* Disable bus master arbitration */
 	pm2_blk = inb(pmbase + 0x20);
 	pm2_blk |= 0x01;
 	outb(pm2_blk, (pmbase + 0x20));

 	/* Actual transition */
 	outb(value, (pmbase + 0x50));

 	/* Restore bus master arbitration */
 	pm2_blk &= 0xfe;
 	outb(pm2_blk, (pmbase + 0x20));

 	/* check if transition was successful */
 	value = inb(pmbase + 0x50);

 	/* Enable IRQs */
 	local_irq_restore(flags);

 	pr_debug("read at pmbase 0x%x + 0x50 returned 0x%x\n", pmbase, value);

 	if (state == (value & 0x1))
 		pr_debug("change to %u MHz succeeded\n",
 			speedstep_get_frequency(speedstep_processor) / 1000);
 	else
 		printk(KERN_ERR "cpufreq: change failed - I/O error\n");

 	return;
 }

 /* Wrapper for smp_call_function_single. */
 static void _speedstep_set_state(void *_state)
 {
 	speedstep_set_state(*(unsigned int *)_state);
 }

 /**
  * speedstep_activate - activate SpeedStep control in the chipset
  *
  *   Tries to activate the SpeedStep status and control registers.
  * Returns -EINVAL on an unsupported chipset, and zero on success.
  */
 static int speedstep_activate(void)
 {
 	u16 value = 0;

 	if (!speedstep_chipset_dev)
 		return -EINVAL;

 	pci_read_config_word(speedstep_chipset_dev, 0x00A0, &value);
 	if (!(value & 0x08)) {
 		value |= 0x08;
 		pr_debug("activating SpeedStep (TM) registers\n");
 		pci_write_config_word(speedstep_chipset_dev, 0x00A0, value);
 	}

 	return 0;
 }


 /**
  * speedstep_detect_chipset - detect the Southbridge which contains SpeedStep logic
  *
  *   Detects ICH2-M, ICH3-M and ICH4-M so far. The pci_dev points to
  * the LPC bridge / PM module which contains all power-management
  * functions. Returns the SPEEDSTEP_CHIPSET_-number for the detected
  * chipset, or zero on failure.
  */
 static unsigned int speedstep_detect_chipset(void)
 {
 	speedstep_chipset_dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
 			      PCI_DEVICE_ID_INTEL_82801DB_12,
 			      PCI_ANY_ID, PCI_ANY_ID,
 			      NULL);
 	if (speedstep_chipset_dev)
 		return 4; /* 4-M */

 	speedstep_chipset_dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
 			      PCI_DEVICE_ID_INTEL_82801CA_12,
 			      PCI_ANY_ID, PCI_ANY_ID,
 			      NULL);
 	if (speedstep_chipset_dev)
 		return 3; /* 3-M */


 	speedstep_chipset_dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
 			      PCI_DEVICE_ID_INTEL_82801BA_10,
 			      PCI_ANY_ID, PCI_ANY_ID,
 			      NULL);
 	if (speedstep_chipset_dev) {
 		/* speedstep.c causes lockups on Dell Inspirons 8000 and
 		 * 8100 which use a pretty old revision of the 82815
 		 * host bridge. Abort on these systems.
 		 */
 		static struct pci_dev *hostbridge;

 		hostbridge  = pci_get_subsys(PCI_VENDOR_ID_INTEL,
 			      PCI_DEVICE_ID_INTEL_82815_MC,
 			      PCI_ANY_ID, PCI_ANY_ID,
 			      NULL);

 		if (!hostbridge)
 			return 2; /* 2-M */

 		if (hostbridge->revision < 5) {
 			pr_debug("hostbridge does not support speedstep\n");
 			speedstep_chipset_dev = NULL;
 			pci_dev_put(hostbridge);
 			return 0;
 		}

 		pci_dev_put(hostbridge);
 		return 2; /* 2-M */
 	}

 	return 0;
 }

 static void get_freq_data(void *_speed)
 {
 	unsigned int *speed = _speed;

 	*speed = speedstep_get_frequency(speedstep_processor);
 }

 static unsigned int speedstep_get(unsigned int cpu)
 {
 	unsigned int speed;

 	/* You're supposed to ensure CPU is online. */
 	if (smp_call_function_single(cpu, get_freq_data, &speed, 1) != 0)
 		BUG();

 	pr_debug("detected %u kHz as current frequency\n", speed);
 	return speed;
 }

 /**
  * speedstep_target - set a new CPUFreq policy
  * @policy: new policy
  * @target_freq: the target frequency
  * @relation: how that frequency relates to achieved frequency
  *	(CPUFREQ_RELATION_L or CPUFREQ_RELATION_H)
  *
  * Sets a new CPUFreq policy.
  */
 static int speedstep_target(struct cpufreq_policy *policy,
 			     unsigned int target_freq,
 			     unsigned int relation)
 {
 	unsigned int newstate = 0, policy_cpu;
 	struct cpufreq_freqs freqs;

 	if (cpufreq_frequency_table_target(policy, &speedstep_freqs[0],
 				target_freq, relation, &newstate))
 		return -EINVAL;

 	policy_cpu = cpumask_any_and(policy->cpus, cpu_online_mask);
 	freqs.old = speedstep_get(policy_cpu);
 	freqs.new = speedstep_freqs[newstate].frequency;

 	pr_debug("transiting from %u to %u kHz\n", freqs.old, freqs.new);

 	/* no transition necessary */
 	if (freqs.old == freqs.new)
 		return 0;

 	cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);

 	smp_call_function_single(policy_cpu, _speedstep_set_state, &newstate,
 				 true);

 	cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);

 	return 0;
 }


 struct get_freqs {
 	struct cpufreq_policy *policy;
 	int ret;
 };

 static void get_freqs_on_cpu(void *_get_freqs)
 {
 	struct get_freqs *get_freqs = _get_freqs;

 	get_freqs->ret =
 		speedstep_get_freqs(speedstep_processor,
 			    &speedstep_freqs[SPEEDSTEP_LOW].frequency,
 			    &speedstep_freqs[SPEEDSTEP_HIGH].frequency,
 			    &get_freqs->policy->cpuinfo.transition_latency,
 			    &speedstep_set_state);
 }

 static int speedstep_cpu_init(struct cpufreq_policy *policy)
 {
 	unsigned int policy_cpu, speed;
 	struct get_freqs gf;

 	/* only run on CPU to be set, or on its sibling */
 #ifdef CONFIG_SMP
 	cpumask_copy(policy->cpus, cpu_sibling_mask(policy->cpu));
 #endif
 	policy_cpu = cpumask_any_and(policy->cpus, cpu_online_mask);

 	/* detect low and high frequency and transition latency */
 	gf.policy = policy;
 	smp_call_function_single(policy_cpu, get_freqs_on_cpu, &gf, 1);
 	if (gf.ret)
 		return gf.ret;

 	/* get current speed setting */
 	speed = speedstep_get(policy_cpu);
 	if (!speed)
 		return -EIO;

 	pr_debug("currently at %s speed setting - %i MHz\n",
 		(speed == speedstep_freqs[SPEEDSTEP_LOW].frequency)
 		? "low" : "high",
 		(speed / 1000));

 	/* cpuinfo and default policy values */
 	policy->cur = speed;

 	return cpufreq_table_validate_and_show(policy, speedstep_freqs);
 }


 static struct cpufreq_driver speedstep_driver = {
 	.name	= "speedstep-ich",
 	.verify	= cpufreq_generic_frequency_table_verify,
 	.target	= speedstep_target,
 	.init	= speedstep_cpu_init,
 	.exit	= cpufreq_generic_exit,
 	.get	= speedstep_get,
 	.attr	= cpufreq_generic_attr,
 };

 static const struct x86_cpu_id ss_smi_ids[] = {
 	{ X86_VENDOR_INTEL, 6, 0xb, },
 	{ X86_VENDOR_INTEL, 6, 0x8, },
 	{ X86_VENDOR_INTEL, 15, 2 },
 	{}
 };
 #if 0
 /* Autoload or not? Do not for now. */
 MODULE_DEVICE_TABLE(x86cpu, ss_smi_ids);
 #endif

 /**
  * speedstep_init - initializes the SpeedStep CPUFreq driver
  *
  *   Initializes the SpeedStep support. Returns -ENODEV on unsupported
  * devices, -EINVAL on problems during initiatization, and zero on
  * success.
  */
 static int __init speedstep_init(void)
 {
 	if (!x86_match_cpu(ss_smi_ids))
 		return -ENODEV;

 	/* detect processor */
 	speedstep_processor = speedstep_detect_processor();
 	if (!speedstep_processor) {
 		pr_debug("Intel(R) SpeedStep(TM) capable processor "
 				"not found\n");
 		return -ENODEV;
 	}

 	/* detect chipset */
 	if (!speedstep_detect_chipset()) {
 		pr_debug("Intel(R) SpeedStep(TM) for this chipset not "
 				"(yet) available.\n");
 		return -ENODEV;
 	}

 	/* activate speedstep support */
 	if (speedstep_activate()) {
 		pci_dev_put(speedstep_chipset_dev);
 		return -EINVAL;
 	}

 	if (speedstep_find_register())
 		return -ENODEV;

 	return cpufreq_register_driver(&speedstep_driver);
 }


 /**
  * speedstep_exit - unregisters SpeedStep support
  *
  *   Unregisters SpeedStep support.
  */
 static void __exit speedstep_exit(void)
 {
 	pci_dev_put(speedstep_chipset_dev);
 	cpufreq_unregister_driver(&speedstep_driver);
 }


 MODULE_AUTHOR("Dave Jones <davej@redhat.com>, "
 		"Dominik Brodowski <linux@brodo.de>");
 MODULE_DESCRIPTION("Speedstep driver for Intel mobile processors on chipsets "
 		"with ICH-M southbridges.");
 MODULE_LICENSE("GPL");

 module_init(speedstep_init);
 module_exit(speedstep_exit);
	/*
	* (C) 2001 Dave Jones, Arjan van de ven.
	* (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
	*
	* Licensed under the terms of the GNU GPL License version 2.
	* Based upon reverse engineered information, and on Intel documentation
	* for chipsets ICH2-M and ICH3-M.
	*
	* Many thanks to Ducrot Bruno for finding and fixing the last
	* "missing link" for ICH2-M/ICH3-M support, and to Thomas Winkler
	* for extensive testing.
	*
	* BIG FAT DISCLAIMER: Work in progress code. Possibly dangerous
	*/


	/*********************************************************************
	* SPEEDSTEP - DEFINITIONS *
	*********************************************************************/

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/cpufreq.h>
	#include <linux/pci.h>
	#include <linux/sched.h>

	#include <asm/cpu_device_id.h>

	#include "speedstep-lib.h"


	/* speedstep_chipset:
	* It is necessary to know which chipset is used. As accesses to
	* this device occur at various places in this module, we need a
	* static struct pci_dev * pointing to that device.
	*/
	static struct pci_dev *speedstep_chipset_dev;


	/* speedstep_processor
	*/
	static enum speedstep_processor speedstep_processor;

	static u32 pmbase;

	/*
	* There are only two frequency states for each processor. Values
	* are in kHz for the time being.
	*/
	static struct cpufreq_frequency_table speedstep_freqs[] = {
	{SPEEDSTEP_HIGH, 0},
	{SPEEDSTEP_LOW, 0},
	{0, CPUFREQ_TABLE_END},
	};


	/**
	* speedstep_find_register - read the PMBASE address
	*
	* Returns: -ENODEV if no register could be found
	*/
	static int speedstep_find_register(void)
	{
	if (!speedstep_chipset_dev)
	return -ENODEV;

	/* get PMBASE */
	pci_read_config_dword(speedstep_chipset_dev, 0x40, &pmbase);
	if (!(pmbase & 0x01)) {
	printk(KERN_ERR "speedstep-ich: could not find speedstep register\n");
	return -ENODEV;
	}

	pmbase &= 0xFFFFFFFE;
	if (!pmbase) {
	printk(KERN_ERR "speedstep-ich: could not find speedstep register\n");
	return -ENODEV;
	}

	pr_debug("pmbase is 0x%x\n", pmbase);
	return 0;
	}

	/**
	* speedstep_set_state - set the SpeedStep state
	* @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
	*
	* Tries to change the SpeedStep state. Can be called from
	* smp_call_function_single.
	*/
	static void speedstep_set_state(unsigned int state)
	{
	u8 pm2_blk;
	u8 value;
	unsigned long flags;

	if (state > 0x1)
	return;

	/* Disable IRQs */
	local_irq_save(flags);

	/* read state */
	value = inb(pmbase + 0x50);

	pr_debug("read at pmbase 0x%x + 0x50 returned 0x%x\n", pmbase, value);

	/* write new state */
	value &= 0xFE;
	value \|= state;

	pr_debug("writing 0x%x to pmbase 0x%x + 0x50\n", value, pmbase);

	/* Disable bus master arbitration */
	pm2_blk = inb(pmbase + 0x20);
	pm2_blk \|= 0x01;
	outb(pm2_blk, (pmbase + 0x20));

	/* Actual transition */
	outb(value, (pmbase + 0x50));

	/* Restore bus master arbitration */
	pm2_blk &= 0xfe;
	outb(pm2_blk, (pmbase + 0x20));

	/* check if transition was successful */
	value = inb(pmbase + 0x50);

	/* Enable IRQs */
	local_irq_restore(flags);

	pr_debug("read at pmbase 0x%x + 0x50 returned 0x%x\n", pmbase, value);

	if (state == (value & 0x1))
	pr_debug("change to %u MHz succeeded\n",
	speedstep_get_frequency(speedstep_processor) / 1000);
	else
	printk(KERN_ERR "cpufreq: change failed - I/O error\n");

	return;
	}

	/* Wrapper for smp_call_function_single. */
	static void _speedstep_set_state(void *_state)
	{
	speedstep_set_state((unsigned int )_state);
	}

	/**
	* speedstep_activate - activate SpeedStep control in the chipset
	*
	* Tries to activate the SpeedStep status and control registers.
	* Returns -EINVAL on an unsupported chipset, and zero on success.
	*/
	static int speedstep_activate(void)
	{
	u16 value = 0;

	if (!speedstep_chipset_dev)
	return -EINVAL;

	pci_read_config_word(speedstep_chipset_dev, 0x00A0, &value);
	if (!(value & 0x08)) {
	value \|= 0x08;
	pr_debug("activating SpeedStep (TM) registers\n");
	pci_write_config_word(speedstep_chipset_dev, 0x00A0, value);
	}

	return 0;
	}


	/**
	* speedstep_detect_chipset - detect the Southbridge which contains SpeedStep logic
	*
	* Detects ICH2-M, ICH3-M and ICH4-M so far. The pci_dev points to
	* the LPC bridge / PM module which contains all power-management
	* functions. Returns the SPEEDSTEP_CHIPSET_-number for the detected
	* chipset, or zero on failure.
	*/
	static unsigned int speedstep_detect_chipset(void)
	{
	speedstep_chipset_dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
	PCI_DEVICE_ID_INTEL_82801DB_12,
	PCI_ANY_ID, PCI_ANY_ID,
	NULL);
	if (speedstep_chipset_dev)
	return 4; /* 4-M */

	speedstep_chipset_dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
	PCI_DEVICE_ID_INTEL_82801CA_12,
	PCI_ANY_ID, PCI_ANY_ID,
	NULL);
	if (speedstep_chipset_dev)
	return 3; /* 3-M */


	speedstep_chipset_dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
	PCI_DEVICE_ID_INTEL_82801BA_10,
	PCI_ANY_ID, PCI_ANY_ID,
	NULL);
	if (speedstep_chipset_dev) {
	/* speedstep.c causes lockups on Dell Inspirons 8000 and
	* 8100 which use a pretty old revision of the 82815
	* host bridge. Abort on these systems.
	*/
	static struct pci_dev *hostbridge;

	hostbridge = pci_get_subsys(PCI_VENDOR_ID_INTEL,
	PCI_DEVICE_ID_INTEL_82815_MC,
	PCI_ANY_ID, PCI_ANY_ID,
	NULL);

	if (!hostbridge)
	return 2; /* 2-M */

	if (hostbridge->revision < 5) {
	pr_debug("hostbridge does not support speedstep\n");
	speedstep_chipset_dev = NULL;
	pci_dev_put(hostbridge);
	return 0;
	}

	pci_dev_put(hostbridge);
	return 2; /* 2-M */
	}

	return 0;
	}

	static void get_freq_data(void *_speed)
	{
	unsigned int *speed = _speed;

	*speed = speedstep_get_frequency(speedstep_processor);
	}

	static unsigned int speedstep_get(unsigned int cpu)
	{
	unsigned int speed;

	/* You're supposed to ensure CPU is online. */
	if (smp_call_function_single(cpu, get_freq_data, &speed, 1) != 0)
	BUG();

	pr_debug("detected %u kHz as current frequency\n", speed);
	return speed;
	}

	/**
	* speedstep_target - set a new CPUFreq policy
	* @policy: new policy
	* @target_freq: the target frequency
	* @relation: how that frequency relates to achieved frequency
	* (CPUFREQ_RELATION_L or CPUFREQ_RELATION_H)
	*
	* Sets a new CPUFreq policy.
	*/
	static int speedstep_target(struct cpufreq_policy *policy,
	unsigned int target_freq,
	unsigned int relation)
	{
	unsigned int newstate = 0, policy_cpu;
	struct cpufreq_freqs freqs;

	if (cpufreq_frequency_table_target(policy, &speedstep_freqs[0],
	target_freq, relation, &newstate))
	return -EINVAL;

	policy_cpu = cpumask_any_and(policy->cpus, cpu_online_mask);
	freqs.old = speedstep_get(policy_cpu);
	freqs.new = speedstep_freqs[newstate].frequency;

	pr_debug("transiting from %u to %u kHz\n", freqs.old, freqs.new);

	/* no transition necessary */
	if (freqs.old == freqs.new)
	return 0;

	cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);

	smp_call_function_single(policy_cpu, _speedstep_set_state, &newstate,
	true);

	cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);

	return 0;
	}


	struct get_freqs {
	struct cpufreq_policy *policy;
	int ret;
	};

	static void get_freqs_on_cpu(void *_get_freqs)
	{
	struct get_freqs *get_freqs = _get_freqs;

	get_freqs->ret =
	speedstep_get_freqs(speedstep_processor,
	&speedstep_freqs[SPEEDSTEP_LOW].frequency,
	&speedstep_freqs[SPEEDSTEP_HIGH].frequency,
	&get_freqs->policy->cpuinfo.transition_latency,
	&speedstep_set_state);
	}

	static int speedstep_cpu_init(struct cpufreq_policy *policy)
	{
	unsigned int policy_cpu, speed;
	struct get_freqs gf;

	/* only run on CPU to be set, or on its sibling */
	#ifdef CONFIG_SMP
	cpumask_copy(policy->cpus, cpu_sibling_mask(policy->cpu));
	#endif
	policy_cpu = cpumask_any_and(policy->cpus, cpu_online_mask);

	/* detect low and high frequency and transition latency */
	gf.policy = policy;
	smp_call_function_single(policy_cpu, get_freqs_on_cpu, &gf, 1);
	if (gf.ret)
	return gf.ret;

	/* get current speed setting */
	speed = speedstep_get(policy_cpu);
	if (!speed)
	return -EIO;

	pr_debug("currently at %s speed setting - %i MHz\n",
	(speed == speedstep_freqs[SPEEDSTEP_LOW].frequency)
	? "low" : "high",
	(speed / 1000));

	/* cpuinfo and default policy values */
	policy->cur = speed;

	return cpufreq_table_validate_and_show(policy, speedstep_freqs);
	}


	static struct cpufreq_driver speedstep_driver = {
	.name = "speedstep-ich",
	.verify = cpufreq_generic_frequency_table_verify,
	.target = speedstep_target,
	.init = speedstep_cpu_init,
	.exit = cpufreq_generic_exit,
	.get = speedstep_get,
	.attr = cpufreq_generic_attr,
	};

	static const struct x86_cpu_id ss_smi_ids[] = {
	{ X86_VENDOR_INTEL, 6, 0xb, },
	{ X86_VENDOR_INTEL, 6, 0x8, },
	{ X86_VENDOR_INTEL, 15, 2 },
	{}
	};
	#if 0
	/* Autoload or not? Do not for now. */
	MODULE_DEVICE_TABLE(x86cpu, ss_smi_ids);
	#endif

	/**
	* speedstep_init - initializes the SpeedStep CPUFreq driver
	*
	* Initializes the SpeedStep support. Returns -ENODEV on unsupported
	* devices, -EINVAL on problems during initiatization, and zero on
	* success.
	*/
	static int __init speedstep_init(void)
	{
	if (!x86_match_cpu(ss_smi_ids))
	return -ENODEV;

	/* detect processor */
	speedstep_processor = speedstep_detect_processor();
	if (!speedstep_processor) {
	pr_debug("Intel(R) SpeedStep(TM) capable processor "
	"not found\n");
	return -ENODEV;
	}

	/* detect chipset */
	if (!speedstep_detect_chipset()) {
	pr_debug("Intel(R) SpeedStep(TM) for this chipset not "
	"(yet) available.\n");
	return -ENODEV;
	}

	/* activate speedstep support */
	if (speedstep_activate()) {
	pci_dev_put(speedstep_chipset_dev);
	return -EINVAL;
	}

	if (speedstep_find_register())
	return -ENODEV;

	return cpufreq_register_driver(&speedstep_driver);
	}


	/**
	* speedstep_exit - unregisters SpeedStep support
	*
	* Unregisters SpeedStep support.
	*/
	static void __exit speedstep_exit(void)
	{
	pci_dev_put(speedstep_chipset_dev);
	cpufreq_unregister_driver(&speedstep_driver);
	}


	MODULE_AUTHOR("Dave Jones <davej@redhat.com>, "
	"Dominik Brodowski <linux@brodo.de>");
	MODULE_DESCRIPTION("Speedstep driver for Intel mobile processors on chipsets "
	"with ICH-M southbridges.");
	MODULE_LICENSE("GPL");

	module_init(speedstep_init);
	module_exit(speedstep_exit);