1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * cpufreq driver for Enhanced SpeedStep, as found in Intel's Pentium
4 * M (part of the Centrino chipset).
5 *
6 * Since the original Pentium M, most new Intel CPUs support Enhanced
7 * SpeedStep.
8 *
9 * Despite the "SpeedStep" in the name, this is almost entirely unlike
10 * traditional SpeedStep.
11 *
12 * Modelled on speedstep.c
13 *
14 * Copyright (C) 2003 Jeremy Fitzhardinge <jeremy@goop.org>
15 */
16
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/init.h>
22 #include <linux/cpufreq.h>
23 #include <linux/sched.h> /* current */
24 #include <linux/delay.h>
25 #include <linux/compiler.h>
26 #include <linux/gfp.h>
27
28 #include <asm/msr.h>
29 #include <asm/processor.h>
30 #include <asm/cpufeature.h>
31 #include <asm/cpu_device_id.h>
32
33 #define MAINTAINER "linux-pm@vger.kernel.org"
34
35 #define INTEL_MSR_RANGE (0xffff)
36
37 struct cpu_id
38 {
39 __u8 x86; /* CPU family */
40 __u8 x86_model; /* model */
41 __u8 x86_stepping; /* stepping */
42 };
43
44 enum {
45 CPU_BANIAS,
46 CPU_DOTHAN_A1,
47 CPU_DOTHAN_A2,
48 CPU_DOTHAN_B0,
49 CPU_MP4HT_D0,
50 CPU_MP4HT_E0,
51 };
52
53 static const struct cpu_id cpu_ids[] = {
54 [CPU_BANIAS] = { 6, 9, 5 },
55 [CPU_DOTHAN_A1] = { 6, 13, 1 },
56 [CPU_DOTHAN_A2] = { 6, 13, 2 },
57 [CPU_DOTHAN_B0] = { 6, 13, 6 },
58 [CPU_MP4HT_D0] = {15, 3, 4 },
59 [CPU_MP4HT_E0] = {15, 4, 1 },
60 };
61 #define N_IDS ARRAY_SIZE(cpu_ids)
62
63 struct cpu_model
64 {
65 const struct cpu_id *cpu_id;
66 const char *model_name;
67 unsigned max_freq; /* max clock in kHz */
68
69 struct cpufreq_frequency_table *op_points; /* clock/voltage pairs */
70 };
71 static int centrino_verify_cpu_id(const struct cpuinfo_x86 *c,
72 const struct cpu_id *x);
73
74 /* Operating points for current CPU */
75 static DEFINE_PER_CPU(struct cpu_model *, centrino_model);
76 static DEFINE_PER_CPU(const struct cpu_id *, centrino_cpu);
77
78 static struct cpufreq_driver centrino_driver;
79
80 #ifdef CONFIG_X86_SPEEDSTEP_CENTRINO_TABLE
81
82 /* Computes the correct form for IA32_PERF_CTL MSR for a particular
83 frequency/voltage operating point; frequency in MHz, volts in mV.
84 This is stored as "driver_data" in the structure. */
85 #define OP(mhz, mv) \
86 { \
87 .frequency = (mhz) * 1000, \
88 .driver_data = (((mhz)/100) << 8) | ((mv - 700) / 16) \
89 }
90
91 /*
92 * These voltage tables were derived from the Intel Pentium M
93 * datasheet, document 25261202.pdf, Table 5. I have verified they
94 * are consistent with my IBM ThinkPad X31, which has a 1.3GHz Pentium
95 * M.
96 */
97
98 /* Ultra Low Voltage Intel Pentium M processor 900MHz (Banias) */
99 static struct cpufreq_frequency_table banias_900[] =
100 {
101 OP(600, 844),
102 OP(800, 988),
103 OP(900, 1004),
104 { .frequency = CPUFREQ_TABLE_END }
105 };
106
107 /* Ultra Low Voltage Intel Pentium M processor 1000MHz (Banias) */
108 static struct cpufreq_frequency_table banias_1000[] =
109 {
110 OP(600, 844),
111 OP(800, 972),
112 OP(900, 988),
113 OP(1000, 1004),
114 { .frequency = CPUFREQ_TABLE_END }
115 };
116
117 /* Low Voltage Intel Pentium M processor 1.10GHz (Banias) */
118 static struct cpufreq_frequency_table banias_1100[] =
119 {
120 OP( 600, 956),
121 OP( 800, 1020),
122 OP( 900, 1100),
123 OP(1000, 1164),
124 OP(1100, 1180),
125 { .frequency = CPUFREQ_TABLE_END }
126 };
127
128
129 /* Low Voltage Intel Pentium M processor 1.20GHz (Banias) */
130 static struct cpufreq_frequency_table banias_1200[] =
131 {
132 OP( 600, 956),
133 OP( 800, 1004),
134 OP( 900, 1020),
135 OP(1000, 1100),
136 OP(1100, 1164),
137 OP(1200, 1180),
138 { .frequency = CPUFREQ_TABLE_END }
139 };
140
141 /* Intel Pentium M processor 1.30GHz (Banias) */
142 static struct cpufreq_frequency_table banias_1300[] =
143 {
144 OP( 600, 956),
145 OP( 800, 1260),
146 OP(1000, 1292),
147 OP(1200, 1356),
148 OP(1300, 1388),
149 { .frequency = CPUFREQ_TABLE_END }
150 };
151
152 /* Intel Pentium M processor 1.40GHz (Banias) */
153 static struct cpufreq_frequency_table banias_1400[] =
154 {
155 OP( 600, 956),
156 OP( 800, 1180),
157 OP(1000, 1308),
158 OP(1200, 1436),
159 OP(1400, 1484),
160 { .frequency = CPUFREQ_TABLE_END }
161 };
162
163 /* Intel Pentium M processor 1.50GHz (Banias) */
164 static struct cpufreq_frequency_table banias_1500[] =
165 {
166 OP( 600, 956),
167 OP( 800, 1116),
168 OP(1000, 1228),
169 OP(1200, 1356),
170 OP(1400, 1452),
171 OP(1500, 1484),
172 { .frequency = CPUFREQ_TABLE_END }
173 };
174
175 /* Intel Pentium M processor 1.60GHz (Banias) */
176 static struct cpufreq_frequency_table banias_1600[] =
177 {
178 OP( 600, 956),
179 OP( 800, 1036),
180 OP(1000, 1164),
181 OP(1200, 1276),
182 OP(1400, 1420),
183 OP(1600, 1484),
184 { .frequency = CPUFREQ_TABLE_END }
185 };
186
187 /* Intel Pentium M processor 1.70GHz (Banias) */
188 static struct cpufreq_frequency_table banias_1700[] =
189 {
190 OP( 600, 956),
191 OP( 800, 1004),
192 OP(1000, 1116),
193 OP(1200, 1228),
194 OP(1400, 1308),
195 OP(1700, 1484),
196 { .frequency = CPUFREQ_TABLE_END }
197 };
198 #undef OP
199
200 #define _BANIAS(cpuid, max, name) \
201 { .cpu_id = cpuid, \
202 .model_name = "Intel(R) Pentium(R) M processor " name "MHz", \
203 .max_freq = (max)*1000, \
204 .op_points = banias_##max, \
205 }
206 #define BANIAS(max) _BANIAS(&cpu_ids[CPU_BANIAS], max, #max)
207
208 /* CPU models, their operating frequency range, and freq/voltage
209 operating points */
210 static struct cpu_model models[] =
211 {
212 _BANIAS(&cpu_ids[CPU_BANIAS], 900, " 900"),
213 BANIAS(1000),
214 BANIAS(1100),
215 BANIAS(1200),
216 BANIAS(1300),
217 BANIAS(1400),
218 BANIAS(1500),
219 BANIAS(1600),
220 BANIAS(1700),
221
222 /* NULL model_name is a wildcard */
223 { &cpu_ids[CPU_DOTHAN_A1], NULL, 0, NULL },
224 { &cpu_ids[CPU_DOTHAN_A2], NULL, 0, NULL },
225 { &cpu_ids[CPU_DOTHAN_B0], NULL, 0, NULL },
226 { &cpu_ids[CPU_MP4HT_D0], NULL, 0, NULL },
227 { &cpu_ids[CPU_MP4HT_E0], NULL, 0, NULL },
228
229 { NULL, }
230 };
231 #undef _BANIAS
232 #undef BANIAS
233
centrino_cpu_init_table(struct cpufreq_policy * policy)234 static int centrino_cpu_init_table(struct cpufreq_policy *policy)
235 {
236 struct cpuinfo_x86 *cpu = &cpu_data(policy->cpu);
237 struct cpu_model *model;
238
239 for(model = models; model->cpu_id != NULL; model++)
240 if (centrino_verify_cpu_id(cpu, model->cpu_id) &&
241 (model->model_name == NULL ||
242 strcmp(cpu->x86_model_id, model->model_name) == 0))
243 break;
244
245 if (model->cpu_id == NULL) {
246 /* No match at all */
247 pr_debug("no support for CPU model \"%s\": "
248 "send /proc/cpuinfo to " MAINTAINER "\n",
249 cpu->x86_model_id);
250 return -ENOENT;
251 }
252
253 if (model->op_points == NULL) {
254 /* Matched a non-match */
255 pr_debug("no table support for CPU model \"%s\"\n",
256 cpu->x86_model_id);
257 pr_debug("try using the acpi-cpufreq driver\n");
258 return -ENOENT;
259 }
260
261 per_cpu(centrino_model, policy->cpu) = model;
262
263 pr_debug("found \"%s\": max frequency: %dkHz\n",
264 model->model_name, model->max_freq);
265
266 return 0;
267 }
268
269 #else
centrino_cpu_init_table(struct cpufreq_policy * policy)270 static inline int centrino_cpu_init_table(struct cpufreq_policy *policy)
271 {
272 return -ENODEV;
273 }
274 #endif /* CONFIG_X86_SPEEDSTEP_CENTRINO_TABLE */
275
centrino_verify_cpu_id(const struct cpuinfo_x86 * c,const struct cpu_id * x)276 static int centrino_verify_cpu_id(const struct cpuinfo_x86 *c,
277 const struct cpu_id *x)
278 {
279 if ((c->x86 == x->x86) &&
280 (c->x86_model == x->x86_model) &&
281 (c->x86_stepping == x->x86_stepping))
282 return 1;
283 return 0;
284 }
285
286 /* To be called only after centrino_model is initialized */
extract_clock(unsigned msr,unsigned int cpu,int failsafe)287 static unsigned extract_clock(unsigned msr, unsigned int cpu, int failsafe)
288 {
289 int i;
290
291 /*
292 * Extract clock in kHz from PERF_CTL value
293 * for centrino, as some DSDTs are buggy.
294 * Ideally, this can be done using the acpi_data structure.
295 */
296 if ((per_cpu(centrino_cpu, cpu) == &cpu_ids[CPU_BANIAS]) ||
297 (per_cpu(centrino_cpu, cpu) == &cpu_ids[CPU_DOTHAN_A1]) ||
298 (per_cpu(centrino_cpu, cpu) == &cpu_ids[CPU_DOTHAN_B0])) {
299 msr = (msr >> 8) & 0xff;
300 return msr * 100000;
301 }
302
303 if ((!per_cpu(centrino_model, cpu)) ||
304 (!per_cpu(centrino_model, cpu)->op_points))
305 return 0;
306
307 msr &= 0xffff;
308 for (i = 0;
309 per_cpu(centrino_model, cpu)->op_points[i].frequency
310 != CPUFREQ_TABLE_END;
311 i++) {
312 if (msr == per_cpu(centrino_model, cpu)->op_points[i].driver_data)
313 return per_cpu(centrino_model, cpu)->
314 op_points[i].frequency;
315 }
316 if (failsafe)
317 return per_cpu(centrino_model, cpu)->op_points[i-1].frequency;
318 else
319 return 0;
320 }
321
322 /* Return the current CPU frequency in kHz */
get_cur_freq(unsigned int cpu)323 static unsigned int get_cur_freq(unsigned int cpu)
324 {
325 unsigned l, h;
326 unsigned clock_freq;
327
328 rdmsr_on_cpu(cpu, MSR_IA32_PERF_STATUS, &l, &h);
329 clock_freq = extract_clock(l, cpu, 0);
330
331 if (unlikely(clock_freq == 0)) {
332 /*
333 * On some CPUs, we can see transient MSR values (which are
334 * not present in _PSS), while CPU is doing some automatic
335 * P-state transition (like TM2). Get the last freq set
336 * in PERF_CTL.
337 */
338 rdmsr_on_cpu(cpu, MSR_IA32_PERF_CTL, &l, &h);
339 clock_freq = extract_clock(l, cpu, 1);
340 }
341 return clock_freq;
342 }
343
344
centrino_cpu_init(struct cpufreq_policy * policy)345 static int centrino_cpu_init(struct cpufreq_policy *policy)
346 {
347 struct cpuinfo_x86 *cpu = &cpu_data(policy->cpu);
348 unsigned l, h;
349 int i;
350
351 /* Only Intel makes Enhanced Speedstep-capable CPUs */
352 if (cpu->x86_vendor != X86_VENDOR_INTEL ||
353 !cpu_has(cpu, X86_FEATURE_EST))
354 return -ENODEV;
355
356 if (cpu_has(cpu, X86_FEATURE_CONSTANT_TSC))
357 centrino_driver.flags |= CPUFREQ_CONST_LOOPS;
358
359 if (policy->cpu != 0)
360 return -ENODEV;
361
362 for (i = 0; i < N_IDS; i++)
363 if (centrino_verify_cpu_id(cpu, &cpu_ids[i]))
364 break;
365
366 if (i != N_IDS)
367 per_cpu(centrino_cpu, policy->cpu) = &cpu_ids[i];
368
369 if (!per_cpu(centrino_cpu, policy->cpu)) {
370 pr_debug("found unsupported CPU with "
371 "Enhanced SpeedStep: send /proc/cpuinfo to "
372 MAINTAINER "\n");
373 return -ENODEV;
374 }
375
376 if (centrino_cpu_init_table(policy))
377 return -ENODEV;
378
379 /* Check to see if Enhanced SpeedStep is enabled, and try to
380 enable it if not. */
381 rdmsr(MSR_IA32_MISC_ENABLE, l, h);
382
383 if (!(l & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
384 l |= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
385 pr_debug("trying to enable Enhanced SpeedStep (%x)\n", l);
386 wrmsr(MSR_IA32_MISC_ENABLE, l, h);
387
388 /* check to see if it stuck */
389 rdmsr(MSR_IA32_MISC_ENABLE, l, h);
390 if (!(l & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
391 pr_info("couldn't enable Enhanced SpeedStep\n");
392 return -ENODEV;
393 }
394 }
395
396 policy->cpuinfo.transition_latency = 10000;
397 /* 10uS transition latency */
398 policy->freq_table = per_cpu(centrino_model, policy->cpu)->op_points;
399
400 return 0;
401 }
402
centrino_cpu_exit(struct cpufreq_policy * policy)403 static void centrino_cpu_exit(struct cpufreq_policy *policy)
404 {
405 unsigned int cpu = policy->cpu;
406
407 if (per_cpu(centrino_model, cpu))
408 per_cpu(centrino_model, cpu) = NULL;
409 }
410
411 /**
412 * centrino_target - set a new CPUFreq policy
413 * @policy: new policy
414 * @index: index of target frequency
415 *
416 * Sets a new CPUFreq policy.
417 */
centrino_target(struct cpufreq_policy * policy,unsigned int index)418 static int centrino_target(struct cpufreq_policy *policy, unsigned int index)
419 {
420 unsigned int msr, oldmsr = 0, h = 0, cpu = policy->cpu;
421 int retval = 0;
422 unsigned int j, first_cpu;
423 struct cpufreq_frequency_table *op_points;
424 cpumask_var_t covered_cpus;
425
426 if (unlikely(!zalloc_cpumask_var(&covered_cpus, GFP_KERNEL)))
427 return -ENOMEM;
428
429 if (unlikely(per_cpu(centrino_model, cpu) == NULL)) {
430 retval = -ENODEV;
431 goto out;
432 }
433
434 first_cpu = 1;
435 op_points = &per_cpu(centrino_model, cpu)->op_points[index];
436 for_each_cpu(j, policy->cpus) {
437 int good_cpu;
438
439 /*
440 * Support for SMP systems.
441 * Make sure we are running on CPU that wants to change freq
442 */
443 if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
444 good_cpu = cpumask_any_and(policy->cpus,
445 cpu_online_mask);
446 else
447 good_cpu = j;
448
449 if (good_cpu >= nr_cpu_ids) {
450 pr_debug("couldn't limit to CPUs in this domain\n");
451 retval = -EAGAIN;
452 if (first_cpu) {
453 /* We haven't started the transition yet. */
454 goto out;
455 }
456 break;
457 }
458
459 msr = op_points->driver_data;
460
461 if (first_cpu) {
462 rdmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, &oldmsr, &h);
463 if (msr == (oldmsr & 0xffff)) {
464 pr_debug("no change needed - msr was and needs "
465 "to be %x\n", oldmsr);
466 retval = 0;
467 goto out;
468 }
469
470 first_cpu = 0;
471 /* all but 16 LSB are reserved, treat them with care */
472 oldmsr &= ~0xffff;
473 msr &= 0xffff;
474 oldmsr |= msr;
475 }
476
477 wrmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, oldmsr, h);
478 if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
479 break;
480
481 cpumask_set_cpu(j, covered_cpus);
482 }
483
484 if (unlikely(retval)) {
485 /*
486 * We have failed halfway through the frequency change.
487 * We have sent callbacks to policy->cpus and
488 * MSRs have already been written on coverd_cpus.
489 * Best effort undo..
490 */
491
492 for_each_cpu(j, covered_cpus)
493 wrmsr_on_cpu(j, MSR_IA32_PERF_CTL, oldmsr, h);
494 }
495 retval = 0;
496
497 out:
498 free_cpumask_var(covered_cpus);
499 return retval;
500 }
501
502 static struct cpufreq_driver centrino_driver = {
503 .name = "centrino", /* should be speedstep-centrino,
504 but there's a 16 char limit */
505 .init = centrino_cpu_init,
506 .exit = centrino_cpu_exit,
507 .verify = cpufreq_generic_frequency_table_verify,
508 .target_index = centrino_target,
509 .get = get_cur_freq,
510 .attr = cpufreq_generic_attr,
511 };
512
513 /*
514 * This doesn't replace the detailed checks above because
515 * the generic CPU IDs don't have a way to match for steppings
516 * or ASCII model IDs.
517 */
518 static const struct x86_cpu_id centrino_ids[] = {
519 X86_MATCH_VFM_FEATURE(IFM( 6, 9), X86_FEATURE_EST, NULL),
520 X86_MATCH_VFM_FEATURE(IFM( 6, 13), X86_FEATURE_EST, NULL),
521 X86_MATCH_VFM_FEATURE(IFM(15, 3), X86_FEATURE_EST, NULL),
522 X86_MATCH_VFM_FEATURE(IFM(15, 4), X86_FEATURE_EST, NULL),
523 {}
524 };
525
526 /**
527 * centrino_init - initializes the Enhanced SpeedStep CPUFreq driver
528 *
529 * Initializes the Enhanced SpeedStep support. Returns -ENODEV on
530 * unsupported devices, -ENOENT if there's no voltage table for this
531 * particular CPU model, -EINVAL on problems during initiatization,
532 * and zero on success.
533 *
534 * This is quite picky. Not only does the CPU have to advertise the
535 * "est" flag in the cpuid capability flags, we look for a specific
536 * CPU model and stepping, and we need to have the exact model name in
537 * our voltage tables. That is, be paranoid about not releasing
538 * someone's valuable magic smoke.
539 */
centrino_init(void)540 static int __init centrino_init(void)
541 {
542 if (!x86_match_cpu(centrino_ids))
543 return -ENODEV;
544 return cpufreq_register_driver(¢rino_driver);
545 }
546
centrino_exit(void)547 static void __exit centrino_exit(void)
548 {
549 cpufreq_unregister_driver(¢rino_driver);
550 }
551
552 MODULE_AUTHOR ("Jeremy Fitzhardinge <jeremy@goop.org>");
553 MODULE_DESCRIPTION ("Enhanced SpeedStep driver for Intel Pentium M processors.");
554 MODULE_LICENSE ("GPL");
555
556 late_initcall(centrino_init);
557 module_exit(centrino_exit);
558