diff -urN oldtree/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c newtree/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c
--- oldtree/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c	2006-02-18 15:18:21.574037496 +0000
+++ newtree/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c	2006-02-18 16:47:17.767812736 +0000
@@ -472,6 +472,151 @@
 static inline int centrino_cpu_init_acpi(struct cpufreq_policy *policy) { return -ENODEV; }
 #endif
 
+static int centrino_target (struct cpufreq_policy *policy,
+			    unsigned int target_freq,
+			    unsigned int relation);
+
+/************************** sysfs interface for user defined voltage table ************************/
+static ssize_t show_user_voltage (struct cpufreq_policy *policy, char *buf)
+{
+	ssize_t       bytes_written = 0;
+	unsigned int  cpu          = policy->cpu;
+	unsigned int  op_index     = 0;
+	unsigned int  voltage      = 0;
+
+	//dprintk("showing user voltage table in sysfs\n");
+
+	while (centrino_model[cpu]->op_points[op_index].frequency != CPUFREQ_TABLE_END)
+	{
+		//dprintk("getting state %i \n", i);
+		voltage = centrino_model[cpu]->op_points[op_index].index;
+		voltage = 700 + ((voltage & 0xFF) << 4); 
+		//dprintk("writing voltage %i: %u mV \n", i, voltage);
+		bytes_written += snprintf (&buf[bytes_written],PAGE_SIZE, "%u",voltage);
+		op_index++;
+		if (centrino_model[cpu]->op_points[op_index].frequency != CPUFREQ_TABLE_END)
+			bytes_written += snprintf (&buf[bytes_written],PAGE_SIZE, ",");
+		else
+			bytes_written += snprintf (&buf[bytes_written],PAGE_SIZE, "\n");	
+	}
+	buf[PAGE_SIZE-1] = 0;
+	return bytes_written;
+}
+
+static ssize_t 
+store_user_voltage (struct cpufreq_policy *policy, const char *buf, size_t count) 
+{
+	unsigned int  cpu;
+	const char   *curr_buf;
+	unsigned int  curr_freq;
+	unsigned int  op_index;
+	int           i;
+	int           isok;
+	char         *next_buf;
+	unsigned int  op_point;
+	ssize_t       retval;
+	unsigned int  voltage;
+
+	static struct cpufreq_frequency_table **original_table = NULL;
+
+	if (!policy)
+	    return -ENODEV;
+	cpu = policy->cpu;
+	if (!centrino_model[cpu] || !centrino_model[cpu]->op_points)
+	    return -ENODEV;
+
+	if (!original_table) 
+	{
+		original_table = kmalloc(sizeof(struct cpufreq_frequency_table *)*NR_CPUS, GFP_KERNEL);
+		for (i=0; i < NR_CPUS; i++)
+		{
+			original_table[i] = NULL;
+		}
+	}
+
+	if (!original_table[cpu]) 
+	{
+		/* Count number of frequencies and allocate memory for a copy */
+		for (i=0; centrino_model[cpu]->op_points[i].frequency != CPUFREQ_TABLE_END; i++);
+		/* Allocate memory to store the copy */
+		original_table[cpu] = (struct cpufreq_frequency_table*) kmalloc(sizeof(struct cpufreq_frequency_table)*(i+1), GFP_KERNEL);
+		/* Make copy of frequency/voltage pairs */
+		for (i=0; centrino_model[cpu]->op_points[i].frequency != CPUFREQ_TABLE_END; i++) 
+		{
+			original_table[cpu][i].frequency = centrino_model[cpu]->op_points[i].frequency;
+			original_table[cpu][i].index = centrino_model[cpu]->op_points[i].index;
+		}
+		original_table[cpu][i].frequency = CPUFREQ_TABLE_END;
+	}
+
+	op_index = 0;
+	curr_buf = buf;
+	next_buf = NULL;
+	isok     = 1;
+	
+	while ((centrino_model[cpu]->op_points[op_index].frequency != CPUFREQ_TABLE_END) 
+		&& (isok))
+	{
+		voltage = simple_strtoul(curr_buf, &next_buf, 10);
+		if ((next_buf != curr_buf) && (next_buf != NULL))
+		{
+			if ((voltage >= 700) && (voltage<=1600))
+			{
+				voltage = ((voltage - 700) >> 4) & 0xFF;
+				op_point = (original_table[cpu])[op_index].index;
+				if (voltage <= (op_point & 0xFF))
+				{
+					//dprintk("setting control value %i to %04x\n", op_index, op_point);
+					op_point = (op_point & 0xFFFFFF00) | voltage;
+					centrino_model[cpu]->op_points[op_index].index = op_point;
+				}
+				else
+				{
+					op_point = (op_point & 0xFFFFFF00) | voltage;
+					dprintk("not setting control value %i to %04x because requested voltage is not lower than the default value\n", op_index, op_point);
+					//isok = 0;
+				}
+			}
+			else
+			{
+				dprintk("voltage value %i is out of bounds: %u mV\n", op_index, voltage);
+				isok = 0;
+			}
+			curr_buf = next_buf;
+			if (*curr_buf==',')
+				curr_buf++;
+			next_buf = NULL;
+		}
+		else
+		{
+			dprintk("failed to parse voltage value %i\n", op_index);
+			isok = 0;
+		}
+		op_index++;
+	}
+
+	if (isok)
+	{
+		retval = count;
+		curr_freq = cpufreq_get(policy->cpu);
+		centrino_target(policy, curr_freq, CPUFREQ_RELATION_L);
+	}
+	else
+	{
+		retval = -EINVAL;
+	}
+
+	return retval;
+}
+
+static struct freq_attr centrino_freq_attr_voltage_table = 
+{
+	.attr = { .name = "voltage_table", .mode = 0644, .owner = THIS_MODULE },
+	.show = show_user_voltage,
+	.store = store_user_voltage,
+};
+
+
 static int centrino_cpu_init(struct cpufreq_policy *policy)
 {
 	struct cpuinfo_x86 *cpu = &cpu_data[policy->cpu];
@@ -655,6 +800,7 @@
 
 static struct freq_attr* centrino_attr[] = {
 	&cpufreq_freq_attr_scaling_available_freqs,
+	&centrino_freq_attr_voltage_table,
 	NULL,
 };
 
diff -urN oldtree/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c.orig newtree/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c.orig
--- oldtree/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c.orig	1970-01-01 00:00:00.000000000 +0000
+++ newtree/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c.orig	2006-02-18 15:18:21.000000000 +0000
@@ -0,0 +1,708 @@
+/*
+ * cpufreq driver for Enhanced SpeedStep, as found in Intel's Pentium
+ * M (part of the Centrino chipset).
+ *
+ * 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>
+ *
+ * WARNING WARNING WARNING
+ *
+ * This driver manipulates the PERF_CTL MSR, which is only somewhat
+ * documented.  While it seems to work on my laptop, it has not been
+ * tested anywhere else, and it may not work for you, do strange
+ * things or simply crash.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/cpufreq.h>
+#include <linux/config.h>
+#include <linux/sched.h>	/* current */
+#include <linux/delay.h>
+#include <linux/compiler.h>
+
+#ifdef CONFIG_X86_SPEEDSTEP_CENTRINO_ACPI
+#include <linux/acpi.h>
+#include <acpi/processor.h>
+#endif
+
+#include <asm/msr.h>
+#include <asm/processor.h>
+#include <asm/cpufeature.h>
+
+#define PFX		"speedstep-centrino: "
+#define MAINTAINER	"Jeremy Fitzhardinge <jeremy@goop.org>"
+
+#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "speedstep-centrino", msg)
+
+
+struct cpu_id
+{
+	__u8	x86;            /* CPU family */
+	__u8	x86_model;	/* model */
+	__u8	x86_mask;	/* 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 struct cpu_model *centrino_model[NR_CPUS];
+static const struct cpu_id *centrino_cpu[NR_CPUS];
+
+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 "index" in the structure. */
+#define OP(mhz, mv)							\
+	{								\
+		.frequency = (mhz) * 1000,				\
+		.index = (((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 */
+		dprintk(KERN_INFO PFX "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 */
+		dprintk(KERN_INFO PFX "no table support for CPU model \"%s\"\n",
+		       cpu->x86_model_id);
+#ifndef CONFIG_X86_SPEEDSTEP_CENTRINO_ACPI
+		dprintk(KERN_INFO PFX "try compiling with CONFIG_X86_SPEEDSTEP_CENTRINO_ACPI enabled\n");
+#endif
+		return -ENOENT;
+	}
+
+	centrino_model[policy->cpu] = model;
+
+	dprintk("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_mask == x->x86_mask))
+		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 ((centrino_cpu[cpu] == &cpu_ids[CPU_BANIAS]) ||
+	    (centrino_cpu[cpu] == &cpu_ids[CPU_DOTHAN_A1]) ||
+	    (centrino_cpu[cpu] == &cpu_ids[CPU_DOTHAN_B0])) {
+		msr = (msr >> 8) & 0xff;
+		return msr * 100000;
+	}
+
+	if ((!centrino_model[cpu]) || (!centrino_model[cpu]->op_points))
+		return 0;
+
+	msr &= 0xffff;
+	for (i=0;centrino_model[cpu]->op_points[i].frequency != CPUFREQ_TABLE_END; i++) {
+		if (msr == centrino_model[cpu]->op_points[i].index)
+			return centrino_model[cpu]->op_points[i].frequency;
+	}
+	if (failsafe)
+		return 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;
+	cpumask_t saved_mask;
+
+	saved_mask = current->cpus_allowed;
+	set_cpus_allowed(current, cpumask_of_cpu(cpu));
+	if (smp_processor_id() != cpu)
+		return 0;
+
+	rdmsr(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(MSR_IA32_PERF_CTL, l, h);
+		clock_freq = extract_clock(l, cpu, 1);
+	}
+
+	set_cpus_allowed(current, saved_mask);
+	return clock_freq;
+}
+
+
+#ifdef CONFIG_X86_SPEEDSTEP_CENTRINO_ACPI
+
+static struct acpi_processor_performance p;
+
+/*
+ * centrino_cpu_init_acpi - register with ACPI P-States library
+ *
+ * Register with the ACPI P-States library (part of drivers/acpi/processor.c)
+ * in order to determine correct frequency and voltage pairings by reading
+ * the _PSS of the ACPI DSDT or SSDT tables.
+ */
+static int centrino_cpu_init_acpi(struct cpufreq_policy *policy)
+{
+	unsigned long			cur_freq;
+	int				result = 0, i;
+	unsigned int			cpu = policy->cpu;
+
+	/* register with ACPI core */
+	if (acpi_processor_register_performance(&p, cpu)) {
+		dprintk(KERN_INFO PFX "obtaining ACPI data failed\n");
+		return -EIO;
+	}
+
+	/* verify the acpi_data */
+	if (p.state_count <= 1) {
+		dprintk("No P-States\n");
+		result = -ENODEV;
+		goto err_unreg;
+	}
+
+	if ((p.control_register.space_id != ACPI_ADR_SPACE_FIXED_HARDWARE) ||
+	    (p.status_register.space_id != ACPI_ADR_SPACE_FIXED_HARDWARE)) {
+		dprintk("Invalid control/status registers (%x - %x)\n",
+			p.control_register.space_id, p.status_register.space_id);
+		result = -EIO;
+		goto err_unreg;
+	}
+
+	for (i=0; i<p.state_count; i++) {
+		if (p.states[i].control != p.states[i].status) {
+			dprintk("Different control (%llu) and status values (%llu)\n",
+				p.states[i].control, p.states[i].status);
+			result = -EINVAL;
+			goto err_unreg;
+		}
+
+		if (!p.states[i].core_frequency) {
+			dprintk("Zero core frequency for state %u\n", i);
+			result = -EINVAL;
+			goto err_unreg;
+		}
+
+		if (p.states[i].core_frequency > p.states[0].core_frequency) {
+			dprintk("P%u has larger frequency (%llu) than P0 (%llu), skipping\n", i,
+				p.states[i].core_frequency, p.states[0].core_frequency);
+			p.states[i].core_frequency = 0;
+			continue;
+		}
+	}
+
+	centrino_model[cpu] = kzalloc(sizeof(struct cpu_model), GFP_KERNEL);
+	if (!centrino_model[cpu]) {
+		result = -ENOMEM;
+		goto err_unreg;
+	}
+
+	centrino_model[cpu]->model_name=NULL;
+	centrino_model[cpu]->max_freq = p.states[0].core_frequency * 1000;
+	centrino_model[cpu]->op_points =  kmalloc(sizeof(struct cpufreq_frequency_table) *
+					     (p.state_count + 1), GFP_KERNEL);
+        if (!centrino_model[cpu]->op_points) {
+                result = -ENOMEM;
+                goto err_kfree;
+        }
+
+        for (i=0; i<p.state_count; i++) {
+		centrino_model[cpu]->op_points[i].index = p.states[i].control;
+		centrino_model[cpu]->op_points[i].frequency = p.states[i].core_frequency * 1000;
+		dprintk("adding state %i with frequency %u and control value %04x\n", 
+			i, centrino_model[cpu]->op_points[i].frequency, centrino_model[cpu]->op_points[i].index);
+	}
+	centrino_model[cpu]->op_points[p.state_count].frequency = CPUFREQ_TABLE_END;
+
+	cur_freq = get_cur_freq(cpu);
+
+	for (i=0; i<p.state_count; i++) {
+		if (!p.states[i].core_frequency) {
+			dprintk("skipping state %u\n", i);
+			centrino_model[cpu]->op_points[i].frequency = CPUFREQ_ENTRY_INVALID;
+			continue;
+		}
+		
+		if (extract_clock(centrino_model[cpu]->op_points[i].index, cpu, 0) !=
+		    (centrino_model[cpu]->op_points[i].frequency)) {
+			dprintk("Invalid encoded frequency (%u vs. %u)\n",
+				extract_clock(centrino_model[cpu]->op_points[i].index, cpu, 0),
+				centrino_model[cpu]->op_points[i].frequency);
+			result = -EINVAL;
+			goto err_kfree_all;
+		}
+
+		if (cur_freq == centrino_model[cpu]->op_points[i].frequency)
+			p.state = i;
+	}
+
+	/* notify BIOS that we exist */
+	acpi_processor_notify_smm(THIS_MODULE);
+
+	return 0;
+
+ err_kfree_all:
+	kfree(centrino_model[cpu]->op_points);
+ err_kfree:
+	kfree(centrino_model[cpu]);
+ err_unreg:
+	acpi_processor_unregister_performance(&p, cpu);
+	dprintk(KERN_INFO PFX "invalid ACPI data\n");
+	return (result);
+}
+#else
+static inline int centrino_cpu_init_acpi(struct cpufreq_policy *policy) { return -ENODEV; }
+#endif
+
+static int centrino_cpu_init(struct cpufreq_policy *policy)
+{
+	struct cpuinfo_x86 *cpu = &cpu_data[policy->cpu];
+	unsigned freq;
+	unsigned l, h;
+	int ret;
+	int i;
+	struct cpuinfo_x86 *c = &cpu_data[policy->cpu];
+
+	/* 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(c, X86_FEATURE_CONSTANT_TSC)) {
+		centrino_driver.flags |= CPUFREQ_CONST_LOOPS;
+	}
+
+	if (centrino_cpu_init_acpi(policy)) {
+		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)
+			centrino_cpu[policy->cpu] = &cpu_ids[i];
+
+		if (!centrino_cpu[policy->cpu]) {
+			dprintk(KERN_INFO PFX "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 & (1<<16))) {
+		l |= (1<<16);
+		dprintk("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 & (1<<16))) {
+			printk(KERN_INFO PFX "couldn't enable Enhanced SpeedStep\n");
+			return -ENODEV;
+		}
+	}
+
+	freq = get_cur_freq(policy->cpu);
+
+	policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
+	policy->cpuinfo.transition_latency = 10000; /* 10uS transition latency */
+	policy->cur = freq;
+
+	dprintk("centrino_cpu_init: cur=%dkHz\n", policy->cur);
+
+	ret = cpufreq_frequency_table_cpuinfo(policy, centrino_model[policy->cpu]->op_points);
+	if (ret)
+		return (ret);
+
+	cpufreq_frequency_table_get_attr(centrino_model[policy->cpu]->op_points, policy->cpu);
+
+	return 0;
+}
+
+static int centrino_cpu_exit(struct cpufreq_policy *policy)
+{
+	unsigned int cpu = policy->cpu;
+
+	if (!centrino_model[cpu])
+		return -ENODEV;
+
+	cpufreq_frequency_table_put_attr(cpu);
+
+#ifdef CONFIG_X86_SPEEDSTEP_CENTRINO_ACPI
+	if (!centrino_model[cpu]->model_name) {
+		dprintk("unregistering and freeing ACPI data\n");
+		acpi_processor_unregister_performance(&p, cpu);
+		kfree(centrino_model[cpu]->op_points);
+		kfree(centrino_model[cpu]);
+	}
+#endif
+
+	centrino_model[cpu] = NULL;
+
+	return 0;
+}
+
+/**
+ * centrino_verify - verifies a new CPUFreq policy
+ * @policy: new policy
+ *
+ * Limit must be within this model's frequency range at least one
+ * border included.
+ */
+static int centrino_verify (struct cpufreq_policy *policy)
+{
+	return cpufreq_frequency_table_verify(policy, centrino_model[policy->cpu]->op_points);
+}
+
+/**
+ * centrino_setpolicy - 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 centrino_target (struct cpufreq_policy *policy,
+			    unsigned int target_freq,
+			    unsigned int relation)
+{
+	unsigned int    newstate = 0;
+	unsigned int	msr, oldmsr, h, cpu = policy->cpu;
+	struct cpufreq_freqs	freqs;
+	cpumask_t		saved_mask;
+	int			retval;
+
+	if (centrino_model[cpu] == NULL)
+		return -ENODEV;
+
+	/*
+	 * Support for SMP systems.
+	 * Make sure we are running on the CPU that wants to change frequency
+	 */
+	saved_mask = current->cpus_allowed;
+	set_cpus_allowed(current, policy->cpus);
+	if (!cpu_isset(smp_processor_id(), policy->cpus)) {
+		dprintk("couldn't limit to CPUs in this domain\n");
+		return(-EAGAIN);
+	}
+
+	if (cpufreq_frequency_table_target(policy, centrino_model[cpu]->op_points, target_freq,
+					   relation, &newstate)) {
+		retval = -EINVAL;
+		goto migrate_end;
+	}
+
+	msr = centrino_model[cpu]->op_points[newstate].index;
+	rdmsr(MSR_IA32_PERF_CTL, oldmsr, h);
+
+	if (msr == (oldmsr & 0xffff)) {
+		retval = 0;
+		dprintk("no change needed - msr was and needs to be %x\n", oldmsr);
+		goto migrate_end;
+	}
+
+	freqs.cpu = cpu;
+	freqs.old = extract_clock(oldmsr, cpu, 0);
+	freqs.new = extract_clock(msr, cpu, 0);
+
+	dprintk("target=%dkHz old=%d new=%d msr=%04x\n",
+		target_freq, freqs.old, freqs.new, msr);
+
+	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+
+	/* all but 16 LSB are "reserved", so treat them with
+	   care */
+	oldmsr &= ~0xffff;
+	msr &= 0xffff;
+	oldmsr |= msr;
+
+	wrmsr(MSR_IA32_PERF_CTL, oldmsr, h);
+
+	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+
+	retval = 0;
+migrate_end:
+	set_cpus_allowed(current, saved_mask);
+	return (retval);
+}
+
+static struct freq_attr* centrino_attr[] = {
+	&cpufreq_freq_attr_scaling_available_freqs,
+	NULL,
+};
+
+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		= centrino_verify,
+	.target		= centrino_target,
+	.get		= get_cur_freq,
+	.attr           = centrino_attr,
+	.owner		= THIS_MODULE,
+};
+
+
+/**
+ * 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)
+{
+	struct cpuinfo_x86 *cpu = cpu_data;
+
+	if (!cpu_has(cpu, X86_FEATURE_EST))
+		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);