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

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * cpufreq driver for Enhanced SpeedStep, as found in Intel's Pentium
  * M (part of the Centrino chipset).
  *
  * Since the original Pentium M, most new Intel CPUs support Enhanced
  * SpeedStep.
  *
  * Despite the "SpeedStep" in the name, this is almost entirely unlike
  * traditional SpeedStep.
  *
  * Modelled on speedstep.c
  *
  * Copyright (C) 2003 Jeremy Fitzhardinge <jeremy@goop.org>
  */

 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/cpufreq.h>
 #include <linux/sched.h>	/* current */
 #include <linux/delay.h>
 #include <linux/compiler.h>
 #include <linux/gfp.h>

 #include <asm/msr.h>
 #include <asm/processor.h>
 #include <asm/cpufeature.h>
 #include <asm/cpu_device_id.h>

 #define MAINTAINER	"linux-pm@vger.kernel.org"

 #define INTEL_MSR_RANGE	(0xffff)

 struct cpu_id
 {
 	__u8	x86;            /* CPU family */
 	__u8	x86_model;	/* model */
 	__u8	x86_stepping;	/* stepping */
 };

 enum {
 	CPU_BANIAS,
 	CPU_DOTHAN_A1,
 	CPU_DOTHAN_A2,
 	CPU_DOTHAN_B0,
 	CPU_MP4HT_D0,
 	CPU_MP4HT_E0,
 };

 static const struct cpu_id cpu_ids[] = {
 	[CPU_BANIAS]	= { 6,  9, 5 },
 	[CPU_DOTHAN_A1]	= { 6, 13, 1 },
 	[CPU_DOTHAN_A2]	= { 6, 13, 2 },
 	[CPU_DOTHAN_B0]	= { 6, 13, 6 },
 	[CPU_MP4HT_D0]	= {15,  3, 4 },
 	[CPU_MP4HT_E0]	= {15,  4, 1 },
 };
 #define N_IDS	ARRAY_SIZE(cpu_ids)

 struct cpu_model
 {
 	const struct cpu_id *cpu_id;
 	const char	*model_name;
 	unsigned	max_freq; /* max clock in kHz */

 	struct cpufreq_frequency_table *op_points; /* clock/voltage pairs */
 };
 static int centrino_verify_cpu_id(const struct cpuinfo_x86 *c,
 				  const struct cpu_id *x);

 /* Operating points for current CPU */
 static DEFINE_PER_CPU(struct cpu_model *, centrino_model);
 static DEFINE_PER_CPU(const struct cpu_id *, centrino_cpu);

 static struct cpufreq_driver centrino_driver;

 #ifdef CONFIG_X86_SPEEDSTEP_CENTRINO_TABLE

 /* Computes the correct form for IA32_PERF_CTL MSR for a particular
    frequency/voltage operating point; frequency in MHz, volts in mV.
    This is stored as "driver_data" in the structure. */
 #define OP(mhz, mv)							\
 	{								\
 		.frequency = (mhz) * 1000,				\
 		.driver_data = (((mhz)/100) << 8) | ((mv - 700) / 16)		\
 	}

 /*
  * These voltage tables were derived from the Intel Pentium M
  * datasheet, document 25261202.pdf, Table 5.  I have verified they
  * are consistent with my IBM ThinkPad X31, which has a 1.3GHz Pentium
  * M.
  */

 /* Ultra Low Voltage Intel Pentium M processor 900MHz (Banias) */
 static struct cpufreq_frequency_table banias_900[] =
 {
 	OP(600,  844),
 	OP(800,  988),
 	OP(900, 1004),
 	{ .frequency = CPUFREQ_TABLE_END }
 };

 /* Ultra Low Voltage Intel Pentium M processor 1000MHz (Banias) */
 static struct cpufreq_frequency_table banias_1000[] =
 {
 	OP(600,   844),
 	OP(800,   972),
 	OP(900,   988),
 	OP(1000, 1004),
 	{ .frequency = CPUFREQ_TABLE_END }
 };

 /* Low Voltage Intel Pentium M processor 1.10GHz (Banias) */
 static struct cpufreq_frequency_table banias_1100[] =
 {
 	OP( 600,  956),
 	OP( 800, 1020),
 	OP( 900, 1100),
 	OP(1000, 1164),
 	OP(1100, 1180),
 	{ .frequency = CPUFREQ_TABLE_END }
 };


 /* Low Voltage Intel Pentium M processor 1.20GHz (Banias) */
 static struct cpufreq_frequency_table banias_1200[] =
 {
 	OP( 600,  956),
 	OP( 800, 1004),
 	OP( 900, 1020),
 	OP(1000, 1100),
 	OP(1100, 1164),
 	OP(1200, 1180),
 	{ .frequency = CPUFREQ_TABLE_END }
 };

 /* Intel Pentium M processor 1.30GHz (Banias) */
 static struct cpufreq_frequency_table banias_1300[] =
 {
 	OP( 600,  956),
 	OP( 800, 1260),
 	OP(1000, 1292),
 	OP(1200, 1356),
 	OP(1300, 1388),
 	{ .frequency = CPUFREQ_TABLE_END }
 };

 /* Intel Pentium M processor 1.40GHz (Banias) */
 static struct cpufreq_frequency_table banias_1400[] =
 {
 	OP( 600,  956),
 	OP( 800, 1180),
 	OP(1000, 1308),
 	OP(1200, 1436),
 	OP(1400, 1484),
 	{ .frequency = CPUFREQ_TABLE_END }
 };

 /* Intel Pentium M processor 1.50GHz (Banias) */
 static struct cpufreq_frequency_table banias_1500[] =
 {
 	OP( 600,  956),
 	OP( 800, 1116),
 	OP(1000, 1228),
 	OP(1200, 1356),
 	OP(1400, 1452),
 	OP(1500, 1484),
 	{ .frequency = CPUFREQ_TABLE_END }
 };

 /* Intel Pentium M processor 1.60GHz (Banias) */
 static struct cpufreq_frequency_table banias_1600[] =
 {
 	OP( 600,  956),
 	OP( 800, 1036),
 	OP(1000, 1164),
 	OP(1200, 1276),
 	OP(1400, 1420),
 	OP(1600, 1484),
 	{ .frequency = CPUFREQ_TABLE_END }
 };

 /* Intel Pentium M processor 1.70GHz (Banias) */
 static struct cpufreq_frequency_table banias_1700[] =
 {
 	OP( 600,  956),
 	OP( 800, 1004),
 	OP(1000, 1116),
 	OP(1200, 1228),
 	OP(1400, 1308),
 	OP(1700, 1484),
 	{ .frequency = CPUFREQ_TABLE_END }
 };
 #undef OP

 #define _BANIAS(cpuid, max, name)	\
 {	.cpu_id		= cpuid,	\
 	.model_name	= "Intel(R) Pentium(R) M processor " name "MHz", \
 	.max_freq	= (max)*1000,	\
 	.op_points	= banias_##max,	\
 }
 #define BANIAS(max)	_BANIAS(&cpu_ids[CPU_BANIAS], max, #max)

 /* CPU models, their operating frequency range, and freq/voltage
    operating points */
 static struct cpu_model models[] =
 {
 	_BANIAS(&cpu_ids[CPU_BANIAS], 900, " 900"),
 	BANIAS(1000),
 	BANIAS(1100),
 	BANIAS(1200),
 	BANIAS(1300),
 	BANIAS(1400),
 	BANIAS(1500),
 	BANIAS(1600),
 	BANIAS(1700),

 	/* NULL model_name is a wildcard */
 	{ &cpu_ids[CPU_DOTHAN_A1], NULL, 0, NULL },
 	{ &cpu_ids[CPU_DOTHAN_A2], NULL, 0, NULL },
 	{ &cpu_ids[CPU_DOTHAN_B0], NULL, 0, NULL },
 	{ &cpu_ids[CPU_MP4HT_D0], NULL, 0, NULL },
 	{ &cpu_ids[CPU_MP4HT_E0], NULL, 0, NULL },

 	{ NULL, }
 };
 #undef _BANIAS
 #undef BANIAS

 static int centrino_cpu_init_table(struct cpufreq_policy *policy)
 {
 	struct cpuinfo_x86 *cpu = &cpu_data(policy->cpu);
 	struct cpu_model *model;

 	for(model = models; model->cpu_id != NULL; model++)
 		if (centrino_verify_cpu_id(cpu, model->cpu_id) &&
 		    (model->model_name == NULL ||
 		     strcmp(cpu->x86_model_id, model->model_name) == 0))
 			break;

 	if (model->cpu_id == NULL) {
 		/* No match at all */
 		pr_debug("no support for CPU model \"%s\": "
 		       "send /proc/cpuinfo to " MAINTAINER "\n",
 		       cpu->x86_model_id);
 		return -ENOENT;
 	}

 	if (model->op_points == NULL) {
 		/* Matched a non-match */
 		pr_debug("no table support for CPU model \"%s\"\n",
 		       cpu->x86_model_id);
 		pr_debug("try using the acpi-cpufreq driver\n");
 		return -ENOENT;
 	}

 	per_cpu(centrino_model, policy->cpu) = model;

 	pr_debug("found \"%s\": max frequency: %dkHz\n",
 	       model->model_name, model->max_freq);

 	return 0;
 }

 #else
 static inline int centrino_cpu_init_table(struct cpufreq_policy *policy)
 {
 	return -ENODEV;
 }
 #endif /* CONFIG_X86_SPEEDSTEP_CENTRINO_TABLE */

 static int centrino_verify_cpu_id(const struct cpuinfo_x86 *c,
 				  const struct cpu_id *x)
 {
 	if ((c->x86 == x->x86) &&
 	    (c->x86_model == x->x86_model) &&
 	    (c->x86_stepping == x->x86_stepping))
 		return 1;
 	return 0;
 }

 /* To be called only after centrino_model is initialized */
 static unsigned extract_clock(unsigned msr, unsigned int cpu, int failsafe)
 {
 	int i;

 	/*
 	 * Extract clock in kHz from PERF_CTL value
 	 * for centrino, as some DSDTs are buggy.
 	 * Ideally, this can be done using the acpi_data structure.
 	 */
 	if ((per_cpu(centrino_cpu, cpu) == &cpu_ids[CPU_BANIAS]) ||
 	    (per_cpu(centrino_cpu, cpu) == &cpu_ids[CPU_DOTHAN_A1]) ||
 	    (per_cpu(centrino_cpu, cpu) == &cpu_ids[CPU_DOTHAN_B0])) {
 		msr = (msr >> 8) & 0xff;
 		return msr * 100000;
 	}

 	if ((!per_cpu(centrino_model, cpu)) ||
 	    (!per_cpu(centrino_model, cpu)->op_points))
 		return 0;

 	msr &= 0xffff;
 	for (i = 0;
 		per_cpu(centrino_model, cpu)->op_points[i].frequency
 							!= CPUFREQ_TABLE_END;
 	     i++) {
 		if (msr == per_cpu(centrino_model, cpu)->op_points[i].driver_data)
 			return per_cpu(centrino_model, cpu)->
 							op_points[i].frequency;
 	}
 	if (failsafe)
 		return per_cpu(centrino_model, cpu)->op_points[i-1].frequency;
 	else
 		return 0;
 }

 /* Return the current CPU frequency in kHz */
 static unsigned int get_cur_freq(unsigned int cpu)
 {
 	unsigned l, h;
 	unsigned clock_freq;

 	rdmsr_on_cpu(cpu, MSR_IA32_PERF_STATUS, &l, &h);
 	clock_freq = extract_clock(l, cpu, 0);

 	if (unlikely(clock_freq == 0)) {
 		/*
 		 * On some CPUs, we can see transient MSR values (which are
 		 * not present in _PSS), while CPU is doing some automatic
 		 * P-state transition (like TM2). Get the last freq set
 		 * in PERF_CTL.
 		 */
 		rdmsr_on_cpu(cpu, MSR_IA32_PERF_CTL, &l, &h);
 		clock_freq = extract_clock(l, cpu, 1);
 	}
 	return clock_freq;
 }


 static int centrino_cpu_init(struct cpufreq_policy *policy)
 {
 	struct cpuinfo_x86 *cpu = &cpu_data(policy->cpu);
 	unsigned l, h;
 	int i;

 	/* Only Intel makes Enhanced Speedstep-capable CPUs */
 	if (cpu->x86_vendor != X86_VENDOR_INTEL ||
 	    !cpu_has(cpu, X86_FEATURE_EST))
 		return -ENODEV;

 	if (cpu_has(cpu, X86_FEATURE_CONSTANT_TSC))
 		centrino_driver.flags |= CPUFREQ_CONST_LOOPS;

 	if (policy->cpu != 0)
 		return -ENODEV;

 	for (i = 0; i < N_IDS; i++)
 		if (centrino_verify_cpu_id(cpu, &cpu_ids[i]))
 			break;

 	if (i != N_IDS)
 		per_cpu(centrino_cpu, policy->cpu) = &cpu_ids[i];

 	if (!per_cpu(centrino_cpu, policy->cpu)) {
 		pr_debug("found unsupported CPU with "
 		"Enhanced SpeedStep: send /proc/cpuinfo to "
 		MAINTAINER "\n");
 		return -ENODEV;
 	}

 	if (centrino_cpu_init_table(policy))
 		return -ENODEV;

 	/* Check to see if Enhanced SpeedStep is enabled, and try to
 	   enable it if not. */
 	rdmsr(MSR_IA32_MISC_ENABLE, l, h);

 	if (!(l & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
 		l |= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
 		pr_debug("trying to enable Enhanced SpeedStep (%x)\n", l);
 		wrmsr(MSR_IA32_MISC_ENABLE, l, h);

 		/* check to see if it stuck */
 		rdmsr(MSR_IA32_MISC_ENABLE, l, h);
 		if (!(l & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
 			pr_info("couldn't enable Enhanced SpeedStep\n");
 			return -ENODEV;
 		}
 	}

 	policy->cpuinfo.transition_latency = 10000;
 						/* 10uS transition latency */
 	policy->freq_table = per_cpu(centrino_model, policy->cpu)->op_points;

 	return 0;
 }

 static void centrino_cpu_exit(struct cpufreq_policy *policy)
 {
 	unsigned int cpu = policy->cpu;

 	if (per_cpu(centrino_model, cpu))
 		per_cpu(centrino_model, cpu) = NULL;
 }

 /**
  * centrino_target - set a new CPUFreq policy
  * @policy: new policy
  * @index: index of target frequency
  *
  * Sets a new CPUFreq policy.
  */
 static int centrino_target(struct cpufreq_policy *policy, unsigned int index)
 {
 	unsigned int	msr, oldmsr = 0, h = 0, cpu = policy->cpu;
 	int			retval = 0;
 	unsigned int		j, first_cpu;
 	struct cpufreq_frequency_table *op_points;
 	cpumask_var_t covered_cpus;

 	if (unlikely(!zalloc_cpumask_var(&covered_cpus, GFP_KERNEL)))
 		return -ENOMEM;

 	if (unlikely(per_cpu(centrino_model, cpu) == NULL)) {
 		retval = -ENODEV;
 		goto out;
 	}

 	first_cpu = 1;
 	op_points = &per_cpu(centrino_model, cpu)->op_points[index];
 	for_each_cpu(j, policy->cpus) {
 		int good_cpu;

 		/*
 		 * Support for SMP systems.
 		 * Make sure we are running on CPU that wants to change freq
 		 */
 		if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
 			good_cpu = cpumask_any_and(policy->cpus,
 						   cpu_online_mask);
 		else
 			good_cpu = j;

 		if (good_cpu >= nr_cpu_ids) {
 			pr_debug("couldn't limit to CPUs in this domain\n");
 			retval = -EAGAIN;
 			if (first_cpu) {
 				/* We haven't started the transition yet. */
 				goto out;
 			}
 			break;
 		}

 		msr = op_points->driver_data;

 		if (first_cpu) {
 			rdmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, &oldmsr, &h);
 			if (msr == (oldmsr & 0xffff)) {
 				pr_debug("no change needed - msr was and needs "
 					"to be %x\n", oldmsr);
 				retval = 0;
 				goto out;
 			}

 			first_cpu = 0;
 			/* all but 16 LSB are reserved, treat them with care */
 			oldmsr &= ~0xffff;
 			msr &= 0xffff;
 			oldmsr |= msr;
 		}

 		wrmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, oldmsr, h);
 		if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
 			break;

 		cpumask_set_cpu(j, covered_cpus);
 	}

 	if (unlikely(retval)) {
 		/*
 		 * We have failed halfway through the frequency change.
 		 * We have sent callbacks to policy->cpus and
 		 * MSRs have already been written on coverd_cpus.
 		 * Best effort undo..
 		 */

 		for_each_cpu(j, covered_cpus)
 			wrmsr_on_cpu(j, MSR_IA32_PERF_CTL, oldmsr, h);
 	}
 	retval = 0;

 out:
 	free_cpumask_var(covered_cpus);
 	return retval;
 }

 static struct cpufreq_driver centrino_driver = {
 	.name		= "centrino", /* should be speedstep-centrino,
 					 but there's a 16 char limit */
 	.init		= centrino_cpu_init,
 	.exit		= centrino_cpu_exit,
 	.verify		= cpufreq_generic_frequency_table_verify,
 	.target_index	= centrino_target,
 	.get		= get_cur_freq,
 	.attr		= cpufreq_generic_attr,
 };

 /*
  * This doesn't replace the detailed checks above because
  * the generic CPU IDs don't have a way to match for steppings
  * or ASCII model IDs.
  */
 static const struct x86_cpu_id centrino_ids[] = {
 	X86_MATCH_VFM_FEATURE(IFM( 6,  9), X86_FEATURE_EST, NULL),
 	X86_MATCH_VFM_FEATURE(IFM( 6, 13), X86_FEATURE_EST, NULL),
 	X86_MATCH_VFM_FEATURE(IFM(15,  3), X86_FEATURE_EST, NULL),
 	X86_MATCH_VFM_FEATURE(IFM(15,  4), X86_FEATURE_EST, NULL),
 	{}
 };

 /**
  * centrino_init - initializes the Enhanced SpeedStep CPUFreq driver
  *
  * Initializes the Enhanced SpeedStep support. Returns -ENODEV on
  * unsupported devices, -ENOENT if there's no voltage table for this
  * particular CPU model, -EINVAL on problems during initiatization,
  * and zero on success.
  *
  * This is quite picky.  Not only does the CPU have to advertise the
  * "est" flag in the cpuid capability flags, we look for a specific
  * CPU model and stepping, and we need to have the exact model name in
  * our voltage tables.  That is, be paranoid about not releasing
  * someone's valuable magic smoke.
  */
 static int __init centrino_init(void)
 {
 	if (!x86_match_cpu(centrino_ids))
 		return -ENODEV;
 	return cpufreq_register_driver(&centrino_driver);
 }

 static void __exit centrino_exit(void)
 {
 	cpufreq_unregister_driver(&centrino_driver);
 }

 MODULE_AUTHOR ("Jeremy Fitzhardinge <jeremy@goop.org>");
 MODULE_DESCRIPTION ("Enhanced SpeedStep driver for Intel Pentium M processors.");
 MODULE_LICENSE ("GPL");

 late_initcall(centrino_init);
 module_exit(centrino_exit);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* cpufreq driver for Enhanced SpeedStep, as found in Intel's Pentium
	* M (part of the Centrino chipset).
	*
	* Since the original Pentium M, most new Intel CPUs support Enhanced
	* SpeedStep.
	*
	* Despite the "SpeedStep" in the name, this is almost entirely unlike
	* traditional SpeedStep.
	*
	* Modelled on speedstep.c
	*
	* Copyright (C) 2003 Jeremy Fitzhardinge <jeremy@goop.org>
	*/

	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/cpufreq.h>
	#include <linux/sched.h> /* current */
	#include <linux/delay.h>
	#include <linux/compiler.h>
	#include <linux/gfp.h>

	#include <asm/msr.h>
	#include <asm/processor.h>
	#include <asm/cpufeature.h>
	#include <asm/cpu_device_id.h>

	#define MAINTAINER "linux-pm@vger.kernel.org"

	#define INTEL_MSR_RANGE (0xffff)

	struct cpu_id
	{
	__u8 x86; /* CPU family */
	__u8 x86_model; /* model */
	__u8 x86_stepping; /* stepping */
	};

	enum {
	CPU_BANIAS,
	CPU_DOTHAN_A1,
	CPU_DOTHAN_A2,
	CPU_DOTHAN_B0,
	CPU_MP4HT_D0,
	CPU_MP4HT_E0,
	};

	static const struct cpu_id cpu_ids[] = {
	[CPU_BANIAS] = { 6, 9, 5 },
	[CPU_DOTHAN_A1] = { 6, 13, 1 },
	[CPU_DOTHAN_A2] = { 6, 13, 2 },
	[CPU_DOTHAN_B0] = { 6, 13, 6 },
	[CPU_MP4HT_D0] = {15, 3, 4 },
	[CPU_MP4HT_E0] = {15, 4, 1 },
	};
	#define N_IDS ARRAY_SIZE(cpu_ids)

	struct cpu_model
	{
	const struct cpu_id *cpu_id;
	const char *model_name;
	unsigned max_freq; /* max clock in kHz */

	struct cpufreq_frequency_table op_points; / clock/voltage pairs */
	};
	static int centrino_verify_cpu_id(const struct cpuinfo_x86 *c,
	const struct cpu_id *x);

	/* Operating points for current CPU */
	static DEFINE_PER_CPU(struct cpu_model *, centrino_model);
	static DEFINE_PER_CPU(const struct cpu_id *, centrino_cpu);

	static struct cpufreq_driver centrino_driver;

	#ifdef CONFIG_X86_SPEEDSTEP_CENTRINO_TABLE

	/* Computes the correct form for IA32_PERF_CTL MSR for a particular
	frequency/voltage operating point; frequency in MHz, volts in mV.
	This is stored as "driver_data" in the structure. */
	#define OP(mhz, mv) \
	{ \
	.frequency = (mhz) * 1000, \
	.driver_data = (((mhz)/100) << 8) \| ((mv - 700) / 16) \
	}

	/*
	* These voltage tables were derived from the Intel Pentium M
	* datasheet, document 25261202.pdf, Table 5. I have verified they
	* are consistent with my IBM ThinkPad X31, which has a 1.3GHz Pentium
	* M.
	*/

	/* Ultra Low Voltage Intel Pentium M processor 900MHz (Banias) */
	static struct cpufreq_frequency_table banias_900[] =
	{
	OP(600, 844),
	OP(800, 988),
	OP(900, 1004),
	{ .frequency = CPUFREQ_TABLE_END }
	};

	/* Ultra Low Voltage Intel Pentium M processor 1000MHz (Banias) */
	static struct cpufreq_frequency_table banias_1000[] =
	{
	OP(600, 844),
	OP(800, 972),
	OP(900, 988),
	OP(1000, 1004),
	{ .frequency = CPUFREQ_TABLE_END }
	};

	/* Low Voltage Intel Pentium M processor 1.10GHz (Banias) */
	static struct cpufreq_frequency_table banias_1100[] =
	{
	OP( 600, 956),
	OP( 800, 1020),
	OP( 900, 1100),
	OP(1000, 1164),
	OP(1100, 1180),
	{ .frequency = CPUFREQ_TABLE_END }
	};


	/* Low Voltage Intel Pentium M processor 1.20GHz (Banias) */
	static struct cpufreq_frequency_table banias_1200[] =
	{
	OP( 600, 956),
	OP( 800, 1004),
	OP( 900, 1020),
	OP(1000, 1100),
	OP(1100, 1164),
	OP(1200, 1180),
	{ .frequency = CPUFREQ_TABLE_END }
	};

	/* Intel Pentium M processor 1.30GHz (Banias) */
	static struct cpufreq_frequency_table banias_1300[] =
	{
	OP( 600, 956),
	OP( 800, 1260),
	OP(1000, 1292),
	OP(1200, 1356),
	OP(1300, 1388),
	{ .frequency = CPUFREQ_TABLE_END }
	};

	/* Intel Pentium M processor 1.40GHz (Banias) */
	static struct cpufreq_frequency_table banias_1400[] =
	{
	OP( 600, 956),
	OP( 800, 1180),
	OP(1000, 1308),
	OP(1200, 1436),
	OP(1400, 1484),
	{ .frequency = CPUFREQ_TABLE_END }
	};

	/* Intel Pentium M processor 1.50GHz (Banias) */
	static struct cpufreq_frequency_table banias_1500[] =
	{
	OP( 600, 956),
	OP( 800, 1116),
	OP(1000, 1228),
	OP(1200, 1356),
	OP(1400, 1452),
	OP(1500, 1484),
	{ .frequency = CPUFREQ_TABLE_END }
	};

	/* Intel Pentium M processor 1.60GHz (Banias) */
	static struct cpufreq_frequency_table banias_1600[] =
	{
	OP( 600, 956),
	OP( 800, 1036),
	OP(1000, 1164),
	OP(1200, 1276),
	OP(1400, 1420),
	OP(1600, 1484),
	{ .frequency = CPUFREQ_TABLE_END }
	};

	/* Intel Pentium M processor 1.70GHz (Banias) */
	static struct cpufreq_frequency_table banias_1700[] =
	{
	OP( 600, 956),
	OP( 800, 1004),
	OP(1000, 1116),
	OP(1200, 1228),
	OP(1400, 1308),
	OP(1700, 1484),
	{ .frequency = CPUFREQ_TABLE_END }
	};
	#undef OP

	#define _BANIAS(cpuid, max, name) \
	{ .cpu_id = cpuid, \
	.model_name = "Intel(R) Pentium(R) M processor " name "MHz", \
	.max_freq = (max)*1000, \
	.op_points = banias_##max, \
	}
	#define BANIAS(max) _BANIAS(&cpu_ids[CPU_BANIAS], max, #max)

	/* CPU models, their operating frequency range, and freq/voltage
	operating points */
	static struct cpu_model models[] =
	{
	_BANIAS(&cpu_ids[CPU_BANIAS], 900, " 900"),
	BANIAS(1000),
	BANIAS(1100),
	BANIAS(1200),
	BANIAS(1300),
	BANIAS(1400),
	BANIAS(1500),
	BANIAS(1600),
	BANIAS(1700),

	/* NULL model_name is a wildcard */
	{ &cpu_ids[CPU_DOTHAN_A1], NULL, 0, NULL },
	{ &cpu_ids[CPU_DOTHAN_A2], NULL, 0, NULL },
	{ &cpu_ids[CPU_DOTHAN_B0], NULL, 0, NULL },
	{ &cpu_ids[CPU_MP4HT_D0], NULL, 0, NULL },
	{ &cpu_ids[CPU_MP4HT_E0], NULL, 0, NULL },

	{ NULL, }
	};
	#undef _BANIAS
	#undef BANIAS

	static int centrino_cpu_init_table(struct cpufreq_policy *policy)
	{
	struct cpuinfo_x86 *cpu = &cpu_data(policy->cpu);
	struct cpu_model *model;

	for(model = models; model->cpu_id != NULL; model++)
	if (centrino_verify_cpu_id(cpu, model->cpu_id) &&
	(model->model_name == NULL \|\|
	strcmp(cpu->x86_model_id, model->model_name) == 0))
	break;

	if (model->cpu_id == NULL) {
	/* No match at all */
	pr_debug("no support for CPU model \"%s\": "
	"send /proc/cpuinfo to " MAINTAINER "\n",
	cpu->x86_model_id);
	return -ENOENT;
	}

	if (model->op_points == NULL) {
	/* Matched a non-match */
	pr_debug("no table support for CPU model \"%s\"\n",
	cpu->x86_model_id);
	pr_debug("try using the acpi-cpufreq driver\n");
	return -ENOENT;
	}

	per_cpu(centrino_model, policy->cpu) = model;

	pr_debug("found \"%s\": max frequency: %dkHz\n",
	model->model_name, model->max_freq);

	return 0;
	}

	#else
	static inline int centrino_cpu_init_table(struct cpufreq_policy *policy)
	{
	return -ENODEV;
	}
	#endif /* CONFIG_X86_SPEEDSTEP_CENTRINO_TABLE */

	static int centrino_verify_cpu_id(const struct cpuinfo_x86 *c,
	const struct cpu_id *x)
	{
	if ((c->x86 == x->x86) &&
	(c->x86_model == x->x86_model) &&
	(c->x86_stepping == x->x86_stepping))
	return 1;
	return 0;
	}

	/* To be called only after centrino_model is initialized */
	static unsigned extract_clock(unsigned msr, unsigned int cpu, int failsafe)
	{
	int i;

	/*
	* Extract clock in kHz from PERF_CTL value
	* for centrino, as some DSDTs are buggy.
	* Ideally, this can be done using the acpi_data structure.
	*/
	if ((per_cpu(centrino_cpu, cpu) == &cpu_ids[CPU_BANIAS]) \|\|
	(per_cpu(centrino_cpu, cpu) == &cpu_ids[CPU_DOTHAN_A1]) \|\|
	(per_cpu(centrino_cpu, cpu) == &cpu_ids[CPU_DOTHAN_B0])) {
	msr = (msr >> 8) & 0xff;
	return msr * 100000;
	}

	if ((!per_cpu(centrino_model, cpu)) \|\|
	(!per_cpu(centrino_model, cpu)->op_points))
	return 0;

	msr &= 0xffff;
	for (i = 0;
	per_cpu(centrino_model, cpu)->op_points[i].frequency
	!= CPUFREQ_TABLE_END;
	i++) {
	if (msr == per_cpu(centrino_model, cpu)->op_points[i].driver_data)
	return per_cpu(centrino_model, cpu)->
	op_points[i].frequency;
	}
	if (failsafe)
	return per_cpu(centrino_model, cpu)->op_points[i-1].frequency;
	else
	return 0;
	}

	/* Return the current CPU frequency in kHz */
	static unsigned int get_cur_freq(unsigned int cpu)
	{
	unsigned l, h;
	unsigned clock_freq;

	rdmsr_on_cpu(cpu, MSR_IA32_PERF_STATUS, &l, &h);
	clock_freq = extract_clock(l, cpu, 0);

	if (unlikely(clock_freq == 0)) {
	/*
	* On some CPUs, we can see transient MSR values (which are
	* not present in _PSS), while CPU is doing some automatic
	* P-state transition (like TM2). Get the last freq set
	* in PERF_CTL.
	*/
	rdmsr_on_cpu(cpu, MSR_IA32_PERF_CTL, &l, &h);
	clock_freq = extract_clock(l, cpu, 1);
	}
	return clock_freq;
	}


	static int centrino_cpu_init(struct cpufreq_policy *policy)
	{
	struct cpuinfo_x86 *cpu = &cpu_data(policy->cpu);
	unsigned l, h;
	int i;

	/* Only Intel makes Enhanced Speedstep-capable CPUs */
	if (cpu->x86_vendor != X86_VENDOR_INTEL \|\|
	!cpu_has(cpu, X86_FEATURE_EST))
	return -ENODEV;

	if (cpu_has(cpu, X86_FEATURE_CONSTANT_TSC))
	centrino_driver.flags \|= CPUFREQ_CONST_LOOPS;

	if (policy->cpu != 0)
	return -ENODEV;

	for (i = 0; i < N_IDS; i++)
	if (centrino_verify_cpu_id(cpu, &cpu_ids[i]))
	break;

	if (i != N_IDS)
	per_cpu(centrino_cpu, policy->cpu) = &cpu_ids[i];

	if (!per_cpu(centrino_cpu, policy->cpu)) {
	pr_debug("found unsupported CPU with "
	"Enhanced SpeedStep: send /proc/cpuinfo to "
	MAINTAINER "\n");
	return -ENODEV;
	}

	if (centrino_cpu_init_table(policy))
	return -ENODEV;

	/* Check to see if Enhanced SpeedStep is enabled, and try to
	enable it if not. */
	rdmsr(MSR_IA32_MISC_ENABLE, l, h);

	if (!(l & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
	l \|= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
	pr_debug("trying to enable Enhanced SpeedStep (%x)\n", l);
	wrmsr(MSR_IA32_MISC_ENABLE, l, h);

	/* check to see if it stuck */
	rdmsr(MSR_IA32_MISC_ENABLE, l, h);
	if (!(l & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
	pr_info("couldn't enable Enhanced SpeedStep\n");
	return -ENODEV;
	}
	}

	policy->cpuinfo.transition_latency = 10000;
	/* 10uS transition latency */
	policy->freq_table = per_cpu(centrino_model, policy->cpu)->op_points;

	return 0;
	}

	static void centrino_cpu_exit(struct cpufreq_policy *policy)
	{
	unsigned int cpu = policy->cpu;

	if (per_cpu(centrino_model, cpu))
	per_cpu(centrino_model, cpu) = NULL;
	}

	/**
	* centrino_target - set a new CPUFreq policy
	* @policy: new policy
	* @index: index of target frequency
	*
	* Sets a new CPUFreq policy.
	*/
	static int centrino_target(struct cpufreq_policy *policy, unsigned int index)
	{
	unsigned int msr, oldmsr = 0, h = 0, cpu = policy->cpu;
	int retval = 0;
	unsigned int j, first_cpu;
	struct cpufreq_frequency_table *op_points;
	cpumask_var_t covered_cpus;

	if (unlikely(!zalloc_cpumask_var(&covered_cpus, GFP_KERNEL)))
	return -ENOMEM;

	if (unlikely(per_cpu(centrino_model, cpu) == NULL)) {
	retval = -ENODEV;
	goto out;
	}

	first_cpu = 1;
	op_points = &per_cpu(centrino_model, cpu)->op_points[index];
	for_each_cpu(j, policy->cpus) {
	int good_cpu;

	/*
	* Support for SMP systems.
	* Make sure we are running on CPU that wants to change freq
	*/
	if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
	good_cpu = cpumask_any_and(policy->cpus,
	cpu_online_mask);
	else
	good_cpu = j;

	if (good_cpu >= nr_cpu_ids) {
	pr_debug("couldn't limit to CPUs in this domain\n");
	retval = -EAGAIN;
	if (first_cpu) {
	/* We haven't started the transition yet. */
	goto out;
	}
	break;
	}

	msr = op_points->driver_data;

	if (first_cpu) {
	rdmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, &oldmsr, &h);
	if (msr == (oldmsr & 0xffff)) {
	pr_debug("no change needed - msr was and needs "
	"to be %x\n", oldmsr);
	retval = 0;
	goto out;
	}

	first_cpu = 0;
	/* all but 16 LSB are reserved, treat them with care */
	oldmsr &= ~0xffff;
	msr &= 0xffff;
	oldmsr \|= msr;
	}

	wrmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, oldmsr, h);
	if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
	break;

	cpumask_set_cpu(j, covered_cpus);
	}

	if (unlikely(retval)) {
	/*
	* We have failed halfway through the frequency change.
	* We have sent callbacks to policy->cpus and
	* MSRs have already been written on coverd_cpus.
	* Best effort undo..
	*/

	for_each_cpu(j, covered_cpus)
	wrmsr_on_cpu(j, MSR_IA32_PERF_CTL, oldmsr, h);
	}
	retval = 0;

	out:
	free_cpumask_var(covered_cpus);
	return retval;
	}

	static struct cpufreq_driver centrino_driver = {
	.name = "centrino", /* should be speedstep-centrino,
	but there's a 16 char limit */
	.init = centrino_cpu_init,
	.exit = centrino_cpu_exit,
	.verify = cpufreq_generic_frequency_table_verify,
	.target_index = centrino_target,
	.get = get_cur_freq,
	.attr = cpufreq_generic_attr,
	};

	/*
	* This doesn't replace the detailed checks above because
	* the generic CPU IDs don't have a way to match for steppings
	* or ASCII model IDs.
	*/
	static const struct x86_cpu_id centrino_ids[] = {
	X86_MATCH_VFM_FEATURE(IFM( 6, 9), X86_FEATURE_EST, NULL),
	X86_MATCH_VFM_FEATURE(IFM( 6, 13), X86_FEATURE_EST, NULL),
	X86_MATCH_VFM_FEATURE(IFM(15, 3), X86_FEATURE_EST, NULL),
	X86_MATCH_VFM_FEATURE(IFM(15, 4), X86_FEATURE_EST, NULL),
	{}
	};

	/**
	* centrino_init - initializes the Enhanced SpeedStep CPUFreq driver
	*
	* Initializes the Enhanced SpeedStep support. Returns -ENODEV on
	* unsupported devices, -ENOENT if there's no voltage table for this
	* particular CPU model, -EINVAL on problems during initiatization,
	* and zero on success.
	*
	* This is quite picky. Not only does the CPU have to advertise the
	* "est" flag in the cpuid capability flags, we look for a specific
	* CPU model and stepping, and we need to have the exact model name in
	* our voltage tables. That is, be paranoid about not releasing
	* someone's valuable magic smoke.
	*/
	static int __init centrino_init(void)
	{
	if (!x86_match_cpu(centrino_ids))
	return -ENODEV;
	return cpufreq_register_driver(&centrino_driver);
	}

	static void __exit centrino_exit(void)
	{
	cpufreq_unregister_driver(&centrino_driver);
	}

	MODULE_AUTHOR ("Jeremy Fitzhardinge <jeremy@goop.org>");
	MODULE_DESCRIPTION ("Enhanced SpeedStep driver for Intel Pentium M processors.");
	MODULE_LICENSE ("GPL");

	late_initcall(centrino_init);
	module_exit(centrino_exit);