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 int centrino_cpu_exit(struct cpufreq_policy *policy)
404 {
405 	unsigned int cpu = policy->cpu;
406 
407 	if (!per_cpu(centrino_model, cpu))
408 		return -ENODEV;
409 
410 	per_cpu(centrino_model, cpu) = NULL;
411 
412 	return 0;
413 }
414 
415 /**
416  * centrino_target - set a new CPUFreq policy
417  * @policy: new policy
418  * @index: index of target frequency
419  *
420  * Sets a new CPUFreq policy.
421  */
centrino_target(struct cpufreq_policy * policy,unsigned int index)422 static int centrino_target(struct cpufreq_policy *policy, unsigned int index)
423 {
424 	unsigned int	msr, oldmsr = 0, h = 0, cpu = policy->cpu;
425 	int			retval = 0;
426 	unsigned int		j, first_cpu;
427 	struct cpufreq_frequency_table *op_points;
428 	cpumask_var_t covered_cpus;
429 
430 	if (unlikely(!zalloc_cpumask_var(&covered_cpus, GFP_KERNEL)))
431 		return -ENOMEM;
432 
433 	if (unlikely(per_cpu(centrino_model, cpu) == NULL)) {
434 		retval = -ENODEV;
435 		goto out;
436 	}
437 
438 	first_cpu = 1;
439 	op_points = &per_cpu(centrino_model, cpu)->op_points[index];
440 	for_each_cpu(j, policy->cpus) {
441 		int good_cpu;
442 
443 		/*
444 		 * Support for SMP systems.
445 		 * Make sure we are running on CPU that wants to change freq
446 		 */
447 		if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
448 			good_cpu = cpumask_any_and(policy->cpus,
449 						   cpu_online_mask);
450 		else
451 			good_cpu = j;
452 
453 		if (good_cpu >= nr_cpu_ids) {
454 			pr_debug("couldn't limit to CPUs in this domain\n");
455 			retval = -EAGAIN;
456 			if (first_cpu) {
457 				/* We haven't started the transition yet. */
458 				goto out;
459 			}
460 			break;
461 		}
462 
463 		msr = op_points->driver_data;
464 
465 		if (first_cpu) {
466 			rdmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, &oldmsr, &h);
467 			if (msr == (oldmsr & 0xffff)) {
468 				pr_debug("no change needed - msr was and needs "
469 					"to be %x\n", oldmsr);
470 				retval = 0;
471 				goto out;
472 			}
473 
474 			first_cpu = 0;
475 			/* all but 16 LSB are reserved, treat them with care */
476 			oldmsr &= ~0xffff;
477 			msr &= 0xffff;
478 			oldmsr |= msr;
479 		}
480 
481 		wrmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, oldmsr, h);
482 		if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
483 			break;
484 
485 		cpumask_set_cpu(j, covered_cpus);
486 	}
487 
488 	if (unlikely(retval)) {
489 		/*
490 		 * We have failed halfway through the frequency change.
491 		 * We have sent callbacks to policy->cpus and
492 		 * MSRs have already been written on coverd_cpus.
493 		 * Best effort undo..
494 		 */
495 
496 		for_each_cpu(j, covered_cpus)
497 			wrmsr_on_cpu(j, MSR_IA32_PERF_CTL, oldmsr, h);
498 	}
499 	retval = 0;
500 
501 out:
502 	free_cpumask_var(covered_cpus);
503 	return retval;
504 }
505 
506 static struct cpufreq_driver centrino_driver = {
507 	.name		= "centrino", /* should be speedstep-centrino,
508 					 but there's a 16 char limit */
509 	.init		= centrino_cpu_init,
510 	.exit		= centrino_cpu_exit,
511 	.verify		= cpufreq_generic_frequency_table_verify,
512 	.target_index	= centrino_target,
513 	.get		= get_cur_freq,
514 	.attr		= cpufreq_generic_attr,
515 };
516 
517 /*
518  * This doesn't replace the detailed checks above because
519  * the generic CPU IDs don't have a way to match for steppings
520  * or ASCII model IDs.
521  */
522 static const struct x86_cpu_id centrino_ids[] = {
523 	X86_MATCH_VENDOR_FAM_MODEL_FEATURE(INTEL,  6,  9, X86_FEATURE_EST, NULL),
524 	X86_MATCH_VENDOR_FAM_MODEL_FEATURE(INTEL,  6, 13, X86_FEATURE_EST, NULL),
525 	X86_MATCH_VENDOR_FAM_MODEL_FEATURE(INTEL, 15,  3, X86_FEATURE_EST, NULL),
526 	X86_MATCH_VENDOR_FAM_MODEL_FEATURE(INTEL, 15,  4, X86_FEATURE_EST, NULL),
527 	{}
528 };
529 
530 /**
531  * centrino_init - initializes the Enhanced SpeedStep CPUFreq driver
532  *
533  * Initializes the Enhanced SpeedStep support. Returns -ENODEV on
534  * unsupported devices, -ENOENT if there's no voltage table for this
535  * particular CPU model, -EINVAL on problems during initiatization,
536  * and zero on success.
537  *
538  * This is quite picky.  Not only does the CPU have to advertise the
539  * "est" flag in the cpuid capability flags, we look for a specific
540  * CPU model and stepping, and we need to have the exact model name in
541  * our voltage tables.  That is, be paranoid about not releasing
542  * someone's valuable magic smoke.
543  */
centrino_init(void)544 static int __init centrino_init(void)
545 {
546 	if (!x86_match_cpu(centrino_ids))
547 		return -ENODEV;
548 	return cpufreq_register_driver(&centrino_driver);
549 }
550 
centrino_exit(void)551 static void __exit centrino_exit(void)
552 {
553 	cpufreq_unregister_driver(&centrino_driver);
554 }
555 
556 MODULE_AUTHOR ("Jeremy Fitzhardinge <jeremy@goop.org>");
557 MODULE_DESCRIPTION ("Enhanced SpeedStep driver for Intel Pentium M processors.");
558 MODULE_LICENSE ("GPL");
559 
560 late_initcall(centrino_init);
561 module_exit(centrino_exit);
562