2 * cpufreq driver for Enhanced SpeedStep, as found in Intel's Pentium
3 * M (part of the Centrino chipset).
5 * Since the original Pentium M, most new Intel CPUs support Enhanced
8 * Despite the "SpeedStep" in the name, this is almost entirely unlike
9 * traditional SpeedStep.
11 * Modelled on speedstep.c
13 * Copyright (C) 2003 Jeremy Fitzhardinge <jeremy@goop.org>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/init.h>
19 #include <linux/cpufreq.h>
20 #include <linux/sched.h> /* current */
21 #include <linux/delay.h>
22 #include <linux/compiler.h>
25 #include <asm/processor.h>
26 #include <asm/cpufeature.h>
28 #define PFX "speedstep-centrino: "
29 #define MAINTAINER "cpufreq@lists.linux.org.uk"
31 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "speedstep-centrino", msg)
33 #define INTEL_MSR_RANGE (0xffff)
37 __u8 x86; /* CPU family */
38 __u8 x86_model; /* model */
39 __u8 x86_mask; /* stepping */
51 static const struct cpu_id cpu_ids[] = {
52 [CPU_BANIAS] = { 6, 9, 5 },
53 [CPU_DOTHAN_A1] = { 6, 13, 1 },
54 [CPU_DOTHAN_A2] = { 6, 13, 2 },
55 [CPU_DOTHAN_B0] = { 6, 13, 6 },
56 [CPU_MP4HT_D0] = {15, 3, 4 },
57 [CPU_MP4HT_E0] = {15, 4, 1 },
59 #define N_IDS ARRAY_SIZE(cpu_ids)
63 const struct cpu_id *cpu_id;
64 const char *model_name;
65 unsigned max_freq; /* max clock in kHz */
67 struct cpufreq_frequency_table *op_points; /* clock/voltage pairs */
69 static int centrino_verify_cpu_id(const struct cpuinfo_x86 *c, const struct cpu_id *x);
71 /* Operating points for current CPU */
72 static struct cpu_model *centrino_model[NR_CPUS];
73 static const struct cpu_id *centrino_cpu[NR_CPUS];
75 static struct cpufreq_driver centrino_driver;
77 #ifdef CONFIG_X86_SPEEDSTEP_CENTRINO_TABLE
79 /* Computes the correct form for IA32_PERF_CTL MSR for a particular
80 frequency/voltage operating point; frequency in MHz, volts in mV.
81 This is stored as "index" in the structure. */
84 .frequency = (mhz) * 1000, \
85 .index = (((mhz)/100) << 8) | ((mv - 700) / 16) \
89 * These voltage tables were derived from the Intel Pentium M
90 * datasheet, document 25261202.pdf, Table 5. I have verified they
91 * are consistent with my IBM ThinkPad X31, which has a 1.3GHz Pentium
95 /* Ultra Low Voltage Intel Pentium M processor 900MHz (Banias) */
96 static struct cpufreq_frequency_table banias_900[] =
101 { .frequency = CPUFREQ_TABLE_END }
104 /* Ultra Low Voltage Intel Pentium M processor 1000MHz (Banias) */
105 static struct cpufreq_frequency_table banias_1000[] =
111 { .frequency = CPUFREQ_TABLE_END }
114 /* Low Voltage Intel Pentium M processor 1.10GHz (Banias) */
115 static struct cpufreq_frequency_table banias_1100[] =
122 { .frequency = CPUFREQ_TABLE_END }
126 /* Low Voltage Intel Pentium M processor 1.20GHz (Banias) */
127 static struct cpufreq_frequency_table banias_1200[] =
135 { .frequency = CPUFREQ_TABLE_END }
138 /* Intel Pentium M processor 1.30GHz (Banias) */
139 static struct cpufreq_frequency_table banias_1300[] =
146 { .frequency = CPUFREQ_TABLE_END }
149 /* Intel Pentium M processor 1.40GHz (Banias) */
150 static struct cpufreq_frequency_table banias_1400[] =
157 { .frequency = CPUFREQ_TABLE_END }
160 /* Intel Pentium M processor 1.50GHz (Banias) */
161 static struct cpufreq_frequency_table banias_1500[] =
169 { .frequency = CPUFREQ_TABLE_END }
172 /* Intel Pentium M processor 1.60GHz (Banias) */
173 static struct cpufreq_frequency_table banias_1600[] =
181 { .frequency = CPUFREQ_TABLE_END }
184 /* Intel Pentium M processor 1.70GHz (Banias) */
185 static struct cpufreq_frequency_table banias_1700[] =
193 { .frequency = CPUFREQ_TABLE_END }
197 #define _BANIAS(cpuid, max, name) \
199 .model_name = "Intel(R) Pentium(R) M processor " name "MHz", \
200 .max_freq = (max)*1000, \
201 .op_points = banias_##max, \
203 #define BANIAS(max) _BANIAS(&cpu_ids[CPU_BANIAS], max, #max)
205 /* CPU models, their operating frequency range, and freq/voltage
207 static struct cpu_model models[] =
209 _BANIAS(&cpu_ids[CPU_BANIAS], 900, " 900"),
219 /* NULL model_name is a wildcard */
220 { &cpu_ids[CPU_DOTHAN_A1], NULL, 0, NULL },
221 { &cpu_ids[CPU_DOTHAN_A2], NULL, 0, NULL },
222 { &cpu_ids[CPU_DOTHAN_B0], NULL, 0, NULL },
223 { &cpu_ids[CPU_MP4HT_D0], NULL, 0, NULL },
224 { &cpu_ids[CPU_MP4HT_E0], NULL, 0, NULL },
231 static int centrino_cpu_init_table(struct cpufreq_policy *policy)
233 struct cpuinfo_x86 *cpu = &cpu_data[policy->cpu];
234 struct cpu_model *model;
236 for(model = models; model->cpu_id != NULL; model++)
237 if (centrino_verify_cpu_id(cpu, model->cpu_id) &&
238 (model->model_name == NULL ||
239 strcmp(cpu->x86_model_id, model->model_name) == 0))
242 if (model->cpu_id == NULL) {
243 /* No match at all */
244 dprintk("no support for CPU model \"%s\": "
245 "send /proc/cpuinfo to " MAINTAINER "\n",
250 if (model->op_points == NULL) {
251 /* Matched a non-match */
252 dprintk("no table support for CPU model \"%s\"\n",
254 dprintk("try using the acpi-cpufreq driver\n");
258 centrino_model[policy->cpu] = model;
260 dprintk("found \"%s\": max frequency: %dkHz\n",
261 model->model_name, model->max_freq);
267 static inline int centrino_cpu_init_table(struct cpufreq_policy *policy) { return -ENODEV; }
268 #endif /* CONFIG_X86_SPEEDSTEP_CENTRINO_TABLE */
270 static int centrino_verify_cpu_id(const struct cpuinfo_x86 *c, const struct cpu_id *x)
272 if ((c->x86 == x->x86) &&
273 (c->x86_model == x->x86_model) &&
274 (c->x86_mask == x->x86_mask))
279 /* To be called only after centrino_model is initialized */
280 static unsigned extract_clock(unsigned msr, unsigned int cpu, int failsafe)
285 * Extract clock in kHz from PERF_CTL value
286 * for centrino, as some DSDTs are buggy.
287 * Ideally, this can be done using the acpi_data structure.
289 if ((centrino_cpu[cpu] == &cpu_ids[CPU_BANIAS]) ||
290 (centrino_cpu[cpu] == &cpu_ids[CPU_DOTHAN_A1]) ||
291 (centrino_cpu[cpu] == &cpu_ids[CPU_DOTHAN_B0])) {
292 msr = (msr >> 8) & 0xff;
296 if ((!centrino_model[cpu]) || (!centrino_model[cpu]->op_points))
300 for (i=0;centrino_model[cpu]->op_points[i].frequency != CPUFREQ_TABLE_END; i++) {
301 if (msr == centrino_model[cpu]->op_points[i].index)
302 return centrino_model[cpu]->op_points[i].frequency;
305 return centrino_model[cpu]->op_points[i-1].frequency;
310 /* Return the current CPU frequency in kHz */
311 static unsigned int get_cur_freq(unsigned int cpu)
315 cpumask_t saved_mask;
317 saved_mask = current->cpus_allowed;
318 set_cpus_allowed(current, cpumask_of_cpu(cpu));
319 if (smp_processor_id() != cpu)
322 rdmsr(MSR_IA32_PERF_STATUS, l, h);
323 clock_freq = extract_clock(l, cpu, 0);
325 if (unlikely(clock_freq == 0)) {
327 * On some CPUs, we can see transient MSR values (which are
328 * not present in _PSS), while CPU is doing some automatic
329 * P-state transition (like TM2). Get the last freq set
332 rdmsr(MSR_IA32_PERF_CTL, l, h);
333 clock_freq = extract_clock(l, cpu, 1);
336 set_cpus_allowed(current, saved_mask);
341 static int centrino_cpu_init(struct cpufreq_policy *policy)
343 struct cpuinfo_x86 *cpu = &cpu_data[policy->cpu];
349 /* Only Intel makes Enhanced Speedstep-capable CPUs */
350 if (cpu->x86_vendor != X86_VENDOR_INTEL || !cpu_has(cpu, X86_FEATURE_EST))
353 if (cpu_has(cpu, X86_FEATURE_CONSTANT_TSC))
354 centrino_driver.flags |= CPUFREQ_CONST_LOOPS;
356 if (policy->cpu != 0)
359 for (i = 0; i < N_IDS; i++)
360 if (centrino_verify_cpu_id(cpu, &cpu_ids[i]))
364 centrino_cpu[policy->cpu] = &cpu_ids[i];
366 if (!centrino_cpu[policy->cpu]) {
367 dprintk("found unsupported CPU with "
368 "Enhanced SpeedStep: send /proc/cpuinfo to "
373 if (centrino_cpu_init_table(policy)) {
377 /* Check to see if Enhanced SpeedStep is enabled, and try to
379 rdmsr(MSR_IA32_MISC_ENABLE, l, h);
381 if (!(l & (1<<16))) {
383 dprintk("trying to enable Enhanced SpeedStep (%x)\n", l);
384 wrmsr(MSR_IA32_MISC_ENABLE, l, h);
386 /* check to see if it stuck */
387 rdmsr(MSR_IA32_MISC_ENABLE, l, h);
388 if (!(l & (1<<16))) {
389 printk(KERN_INFO PFX "couldn't enable Enhanced SpeedStep\n");
394 freq = get_cur_freq(policy->cpu);
396 policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
397 policy->cpuinfo.transition_latency = 10000; /* 10uS transition latency */
400 dprintk("centrino_cpu_init: cur=%dkHz\n", policy->cur);
402 ret = cpufreq_frequency_table_cpuinfo(policy, centrino_model[policy->cpu]->op_points);
406 cpufreq_frequency_table_get_attr(centrino_model[policy->cpu]->op_points, policy->cpu);
411 static int centrino_cpu_exit(struct cpufreq_policy *policy)
413 unsigned int cpu = policy->cpu;
415 if (!centrino_model[cpu])
418 cpufreq_frequency_table_put_attr(cpu);
420 centrino_model[cpu] = NULL;
426 * centrino_verify - verifies a new CPUFreq policy
427 * @policy: new policy
429 * Limit must be within this model's frequency range at least one
432 static int centrino_verify (struct cpufreq_policy *policy)
434 return cpufreq_frequency_table_verify(policy, centrino_model[policy->cpu]->op_points);
438 * centrino_setpolicy - set a new CPUFreq policy
439 * @policy: new policy
440 * @target_freq: the target frequency
441 * @relation: how that frequency relates to achieved frequency (CPUFREQ_RELATION_L or CPUFREQ_RELATION_H)
443 * Sets a new CPUFreq policy.
445 static int centrino_target (struct cpufreq_policy *policy,
446 unsigned int target_freq,
447 unsigned int relation)
449 unsigned int newstate = 0;
450 unsigned int msr, oldmsr = 0, h = 0, cpu = policy->cpu;
451 struct cpufreq_freqs freqs;
452 cpumask_t online_policy_cpus;
453 cpumask_t saved_mask;
455 cpumask_t covered_cpus;
457 unsigned int j, k, first_cpu, tmp;
459 if (unlikely(centrino_model[cpu] == NULL))
462 if (unlikely(cpufreq_frequency_table_target(policy,
463 centrino_model[cpu]->op_points,
470 #ifdef CONFIG_HOTPLUG_CPU
471 /* cpufreq holds the hotplug lock, so we are safe from here on */
472 cpus_and(online_policy_cpus, cpu_online_map, policy->cpus);
474 online_policy_cpus = policy->cpus;
477 saved_mask = current->cpus_allowed;
479 cpus_clear(covered_cpus);
480 for_each_cpu_mask(j, online_policy_cpus) {
482 * Support for SMP systems.
483 * Make sure we are running on CPU that wants to change freq
485 cpus_clear(set_mask);
486 if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
487 cpus_or(set_mask, set_mask, online_policy_cpus);
489 cpu_set(j, set_mask);
491 set_cpus_allowed(current, set_mask);
493 if (unlikely(!cpu_isset(smp_processor_id(), set_mask))) {
494 dprintk("couldn't limit to CPUs in this domain\n");
497 /* We haven't started the transition yet. */
504 msr = centrino_model[cpu]->op_points[newstate].index;
507 rdmsr(MSR_IA32_PERF_CTL, oldmsr, h);
508 if (msr == (oldmsr & 0xffff)) {
509 dprintk("no change needed - msr was and needs "
510 "to be %x\n", oldmsr);
515 freqs.old = extract_clock(oldmsr, cpu, 0);
516 freqs.new = extract_clock(msr, cpu, 0);
518 dprintk("target=%dkHz old=%d new=%d msr=%04x\n",
519 target_freq, freqs.old, freqs.new, msr);
521 for_each_cpu_mask(k, online_policy_cpus) {
523 cpufreq_notify_transition(&freqs,
528 /* all but 16 LSB are reserved, treat them with care */
534 wrmsr(MSR_IA32_PERF_CTL, oldmsr, h);
535 if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) {
540 cpu_set(j, covered_cpus);
544 for_each_cpu_mask(k, online_policy_cpus) {
546 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
549 if (unlikely(retval)) {
551 * We have failed halfway through the frequency change.
552 * We have sent callbacks to policy->cpus and
553 * MSRs have already been written on coverd_cpus.
557 if (!cpus_empty(covered_cpus)) {
558 for_each_cpu_mask(j, covered_cpus) {
559 set_cpus_allowed(current, cpumask_of_cpu(j));
560 wrmsr(MSR_IA32_PERF_CTL, oldmsr, h);
565 freqs.new = freqs.old;
567 for_each_cpu_mask(j, online_policy_cpus) {
569 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
570 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
573 set_cpus_allowed(current, saved_mask);
578 set_cpus_allowed(current, saved_mask);
582 static struct freq_attr* centrino_attr[] = {
583 &cpufreq_freq_attr_scaling_available_freqs,
587 static struct cpufreq_driver centrino_driver = {
588 .name = "centrino", /* should be speedstep-centrino,
589 but there's a 16 char limit */
590 .init = centrino_cpu_init,
591 .exit = centrino_cpu_exit,
592 .verify = centrino_verify,
593 .target = centrino_target,
595 .attr = centrino_attr,
596 .owner = THIS_MODULE,
601 * centrino_init - initializes the Enhanced SpeedStep CPUFreq driver
603 * Initializes the Enhanced SpeedStep support. Returns -ENODEV on
604 * unsupported devices, -ENOENT if there's no voltage table for this
605 * particular CPU model, -EINVAL on problems during initiatization,
606 * and zero on success.
608 * This is quite picky. Not only does the CPU have to advertise the
609 * "est" flag in the cpuid capability flags, we look for a specific
610 * CPU model and stepping, and we need to have the exact model name in
611 * our voltage tables. That is, be paranoid about not releasing
612 * someone's valuable magic smoke.
614 static int __init centrino_init(void)
616 struct cpuinfo_x86 *cpu = cpu_data;
618 if (!cpu_has(cpu, X86_FEATURE_EST))
621 return cpufreq_register_driver(¢rino_driver);
624 static void __exit centrino_exit(void)
626 cpufreq_unregister_driver(¢rino_driver);
629 MODULE_AUTHOR ("Jeremy Fitzhardinge <jeremy@goop.org>");
630 MODULE_DESCRIPTION ("Enhanced SpeedStep driver for Intel Pentium M processors.");
631 MODULE_LICENSE ("GPL");
633 late_initcall(centrino_init);
634 module_exit(centrino_exit);