xref: /freebsd/sys/kern/kern_cpu.c (revision 2b743a9e9ddc6736208dc8ca1ce06ce64ad20a19)
1 /*-
2  * Copyright (c) 2004-2005 Nate Lawson (SDG)
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  */
26 
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29 
30 #include <sys/param.h>
31 #include <sys/bus.h>
32 #include <sys/cpu.h>
33 #include <sys/eventhandler.h>
34 #include <sys/kernel.h>
35 #include <sys/lock.h>
36 #include <sys/malloc.h>
37 #include <sys/module.h>
38 #include <sys/proc.h>
39 #include <sys/queue.h>
40 #include <sys/sched.h>
41 #include <sys/sysctl.h>
42 #include <sys/systm.h>
43 #include <sys/sbuf.h>
44 #include <sys/sx.h>
45 #include <sys/timetc.h>
46 
47 #include "cpufreq_if.h"
48 
49 /*
50  * Common CPU frequency glue code.  Drivers for specific hardware can
51  * attach this interface to allow users to get/set the CPU frequency.
52  */
53 
54 /*
55  * Number of levels we can handle.  Levels are synthesized from settings
56  * so for M settings and N drivers, there may be M*N levels.
57  */
58 #define CF_MAX_LEVELS	64
59 
60 struct cf_saved_freq {
61 	struct cf_level			level;
62 	int				priority;
63 	SLIST_ENTRY(cf_saved_freq)	link;
64 };
65 
66 struct cpufreq_softc {
67 	struct sx			lock;
68 	struct cf_level			curr_level;
69 	int				curr_priority;
70 	SLIST_HEAD(, cf_saved_freq)	saved_freq;
71 	struct cf_level_lst		all_levels;
72 	int				all_count;
73 	int				max_mhz;
74 	device_t			dev;
75 	struct sysctl_ctx_list		sysctl_ctx;
76 };
77 
78 struct cf_setting_array {
79 	struct cf_setting		sets[MAX_SETTINGS];
80 	int				count;
81 	TAILQ_ENTRY(cf_setting_array)	link;
82 };
83 
84 TAILQ_HEAD(cf_setting_lst, cf_setting_array);
85 
86 #define CF_MTX_INIT(x)		sx_init((x), "cpufreq lock")
87 #define CF_MTX_LOCK(x)		sx_xlock((x))
88 #define CF_MTX_UNLOCK(x)	sx_xunlock((x))
89 #define CF_MTX_ASSERT(x)	sx_assert((x), SX_XLOCKED)
90 
91 #define CF_DEBUG(msg...)	do {		\
92 	if (cf_verbose)				\
93 		printf("cpufreq: " msg);	\
94 	} while (0)
95 
96 static int	cpufreq_attach(device_t dev);
97 static int	cpufreq_detach(device_t dev);
98 static void	cpufreq_evaluate(void *arg);
99 static int	cf_set_method(device_t dev, const struct cf_level *level,
100 		    int priority);
101 static int	cf_get_method(device_t dev, struct cf_level *level);
102 static int	cf_levels_method(device_t dev, struct cf_level *levels,
103 		    int *count);
104 static int	cpufreq_insert_abs(struct cpufreq_softc *sc,
105 		    struct cf_setting *sets, int count);
106 static int	cpufreq_expand_set(struct cpufreq_softc *sc,
107 		    struct cf_setting_array *set_arr);
108 static struct cf_level *cpufreq_dup_set(struct cpufreq_softc *sc,
109 		    struct cf_level *dup, struct cf_setting *set);
110 static int	cpufreq_curr_sysctl(SYSCTL_HANDLER_ARGS);
111 static int	cpufreq_levels_sysctl(SYSCTL_HANDLER_ARGS);
112 static int	cpufreq_settings_sysctl(SYSCTL_HANDLER_ARGS);
113 
114 static device_method_t cpufreq_methods[] = {
115 	DEVMETHOD(device_probe,		bus_generic_probe),
116 	DEVMETHOD(device_attach,	cpufreq_attach),
117 	DEVMETHOD(device_detach,	cpufreq_detach),
118 
119         DEVMETHOD(cpufreq_set,		cf_set_method),
120         DEVMETHOD(cpufreq_get,		cf_get_method),
121         DEVMETHOD(cpufreq_levels,	cf_levels_method),
122 	{0, 0}
123 };
124 static driver_t cpufreq_driver = {
125 	"cpufreq", cpufreq_methods, sizeof(struct cpufreq_softc)
126 };
127 static devclass_t cpufreq_dc;
128 DRIVER_MODULE(cpufreq, cpu, cpufreq_driver, cpufreq_dc, 0, 0);
129 
130 static eventhandler_tag	cf_ev_tag;
131 
132 static int		cf_lowest_freq;
133 static int		cf_verbose;
134 TUNABLE_INT("debug.cpufreq.lowest", &cf_lowest_freq);
135 TUNABLE_INT("debug.cpufreq.verbose", &cf_verbose);
136 SYSCTL_NODE(_debug, OID_AUTO, cpufreq, CTLFLAG_RD, NULL, "cpufreq debugging");
137 SYSCTL_INT(_debug_cpufreq, OID_AUTO, lowest, CTLFLAG_RW, &cf_lowest_freq, 1,
138     "Don't provide levels below this frequency.");
139 SYSCTL_INT(_debug_cpufreq, OID_AUTO, verbose, CTLFLAG_RW, &cf_verbose, 1,
140     "Print verbose debugging messages");
141 
142 static int
143 cpufreq_attach(device_t dev)
144 {
145 	struct cpufreq_softc *sc;
146 	device_t parent;
147 	int numdevs;
148 
149 	CF_DEBUG("initializing %s\n", device_get_nameunit(dev));
150 	sc = device_get_softc(dev);
151 	parent = device_get_parent(dev);
152 	sc->dev = dev;
153 	sysctl_ctx_init(&sc->sysctl_ctx);
154 	TAILQ_INIT(&sc->all_levels);
155 	CF_MTX_INIT(&sc->lock);
156 	sc->curr_level.total_set.freq = CPUFREQ_VAL_UNKNOWN;
157 	SLIST_INIT(&sc->saved_freq);
158 	sc->max_mhz = CPUFREQ_VAL_UNKNOWN;
159 
160 	/*
161 	 * Only initialize one set of sysctls for all CPUs.  In the future,
162 	 * if multiple CPUs can have different settings, we can move these
163 	 * sysctls to be under every CPU instead of just the first one.
164 	 */
165 	numdevs = devclass_get_count(cpufreq_dc);
166 	if (numdevs > 1)
167 		return (0);
168 
169 	CF_DEBUG("initializing one-time data for %s\n",
170 	    device_get_nameunit(dev));
171 	SYSCTL_ADD_PROC(&sc->sysctl_ctx,
172 	    SYSCTL_CHILDREN(device_get_sysctl_tree(parent)),
173 	    OID_AUTO, "freq", CTLTYPE_INT | CTLFLAG_RW, sc, 0,
174 	    cpufreq_curr_sysctl, "I", "Current CPU frequency");
175 	SYSCTL_ADD_PROC(&sc->sysctl_ctx,
176 	    SYSCTL_CHILDREN(device_get_sysctl_tree(parent)),
177 	    OID_AUTO, "freq_levels", CTLTYPE_STRING | CTLFLAG_RD, sc, 0,
178 	    cpufreq_levels_sysctl, "A", "CPU frequency levels");
179 	cf_ev_tag = EVENTHANDLER_REGISTER(cpufreq_changed, cpufreq_evaluate,
180 	    NULL, EVENTHANDLER_PRI_ANY);
181 
182 	return (0);
183 }
184 
185 static int
186 cpufreq_detach(device_t dev)
187 {
188 	struct cpufreq_softc *sc;
189 	struct cf_saved_freq *saved_freq;
190 	int numdevs;
191 
192 	CF_DEBUG("shutdown %s\n", device_get_nameunit(dev));
193 	sc = device_get_softc(dev);
194 	sysctl_ctx_free(&sc->sysctl_ctx);
195 
196 	while ((saved_freq = SLIST_FIRST(&sc->saved_freq)) != NULL) {
197 		SLIST_REMOVE_HEAD(&sc->saved_freq, link);
198 		free(saved_freq, M_TEMP);
199 	}
200 
201 	/* Only clean up these resources when the last device is detaching. */
202 	numdevs = devclass_get_count(cpufreq_dc);
203 	if (numdevs == 1) {
204 		CF_DEBUG("final shutdown for %s\n", device_get_nameunit(dev));
205 		EVENTHANDLER_DEREGISTER(cpufreq_changed, cf_ev_tag);
206 	}
207 
208 	return (0);
209 }
210 
211 static void
212 cpufreq_evaluate(void *arg)
213 {
214 	/* TODO: Re-evaluate when notified of changes to drivers. */
215 }
216 
217 static int
218 cf_set_method(device_t dev, const struct cf_level *level, int priority)
219 {
220 	struct cpufreq_softc *sc;
221 	const struct cf_setting *set;
222 	struct cf_saved_freq *saved_freq, *curr_freq;
223 	struct pcpu *pc;
224 	int cpu_id, error, i;
225 	static int once;
226 
227 	sc = device_get_softc(dev);
228 	error = 0;
229 	set = NULL;
230 	saved_freq = NULL;
231 
232 	/*
233 	 * Check that the TSC isn't being used as a timecounter.
234 	 * If it is, then return EBUSY and refuse to change the
235 	 * clock speed.
236 	 */
237 	if (strcmp(timecounter->tc_name, "TSC") == 0) {
238 		if (!once) {
239 			printf("cpufreq: frequency change with timecounter"
240 				" TSC not allowed, see cpufreq(4)\n");
241 			once = 1;
242 		}
243 		return (EBUSY);
244 	}
245 
246 	CF_MTX_LOCK(&sc->lock);
247 
248 	/*
249 	 * If the requested level has a lower priority, don't allow
250 	 * the new level right now.
251 	 */
252 	if (priority < sc->curr_priority) {
253 		CF_DEBUG("ignoring, curr prio %d less than %d\n", priority,
254 		    sc->curr_priority);
255 		error = EPERM;
256 		goto out;
257 	}
258 
259 	/*
260 	 * If the caller didn't specify a level and one is saved, prepare to
261 	 * restore the saved level.  If none has been saved, return an error.
262 	 */
263 	if (level == NULL) {
264 		saved_freq = SLIST_FIRST(&sc->saved_freq);
265 		if (saved_freq == NULL) {
266 			CF_DEBUG("NULL level, no saved level\n");
267 			error = ENXIO;
268 			goto out;
269 		}
270 		level = &saved_freq->level;
271 		priority = saved_freq->priority;
272 		CF_DEBUG("restoring saved level, freq %d prio %d\n",
273 		    level->total_set.freq, priority);
274 	}
275 
276 	/* Reject levels that are below our specified threshold. */
277 	if (level->total_set.freq < cf_lowest_freq) {
278 		CF_DEBUG("rejecting freq %d, less than %d limit\n",
279 		    level->total_set.freq, cf_lowest_freq);
280 		error = EINVAL;
281 		goto out;
282 	}
283 
284 	/* If already at this level, just return. */
285 	if (CPUFREQ_CMP(sc->curr_level.total_set.freq, level->total_set.freq)) {
286 		CF_DEBUG("skipping freq %d, same as current level %d\n",
287 		    level->total_set.freq, sc->curr_level.total_set.freq);
288 		goto skip;
289 	}
290 
291 	/* First, set the absolute frequency via its driver. */
292 	set = &level->abs_set;
293 	if (set->dev) {
294 		if (!device_is_attached(set->dev)) {
295 			error = ENXIO;
296 			goto out;
297 		}
298 
299 		/* Bind to the target CPU before switching, if necessary. */
300 		cpu_id = PCPU_GET(cpuid);
301 		pc = cpu_get_pcpu(set->dev);
302 		if (cpu_id != pc->pc_cpuid) {
303 			mtx_lock_spin(&sched_lock);
304 			sched_bind(curthread, pc->pc_cpuid);
305 			mtx_unlock_spin(&sched_lock);
306 		}
307 		CF_DEBUG("setting abs freq %d on %s (cpu %d)\n", set->freq,
308 		    device_get_nameunit(set->dev), PCPU_GET(cpuid));
309 		error = CPUFREQ_DRV_SET(set->dev, set);
310 		if (cpu_id != pc->pc_cpuid) {
311 			mtx_lock_spin(&sched_lock);
312 			sched_unbind(curthread);
313 			mtx_unlock_spin(&sched_lock);
314 		}
315 		if (error) {
316 			goto out;
317 		}
318 	}
319 
320 	/* Next, set any/all relative frequencies via their drivers. */
321 	for (i = 0; i < level->rel_count; i++) {
322 		set = &level->rel_set[i];
323 		if (!device_is_attached(set->dev)) {
324 			error = ENXIO;
325 			goto out;
326 		}
327 
328 		/* Bind to the target CPU before switching, if necessary. */
329 		cpu_id = PCPU_GET(cpuid);
330 		pc = cpu_get_pcpu(set->dev);
331 		if (cpu_id != pc->pc_cpuid) {
332 			mtx_lock_spin(&sched_lock);
333 			sched_bind(curthread, pc->pc_cpuid);
334 			mtx_unlock_spin(&sched_lock);
335 		}
336 		CF_DEBUG("setting rel freq %d on %s (cpu %d)\n", set->freq,
337 		    device_get_nameunit(set->dev), PCPU_GET(cpuid));
338 		error = CPUFREQ_DRV_SET(set->dev, set);
339 		if (cpu_id != pc->pc_cpuid) {
340 			mtx_lock_spin(&sched_lock);
341 			sched_unbind(curthread);
342 			mtx_unlock_spin(&sched_lock);
343 		}
344 		if (error) {
345 			/* XXX Back out any successful setting? */
346 			goto out;
347 		}
348 	}
349 
350 skip:
351 	/*
352 	 * Before recording the current level, check if we're going to a
353 	 * higher priority.  If so, save the previous level and priority.
354 	 */
355 	if (sc->curr_level.total_set.freq != CPUFREQ_VAL_UNKNOWN &&
356 	    priority > sc->curr_priority) {
357 		CF_DEBUG("saving level, freq %d prio %d\n",
358 		    sc->curr_level.total_set.freq, sc->curr_priority);
359 		curr_freq = malloc(sizeof(*curr_freq), M_TEMP, M_NOWAIT);
360 		if (curr_freq == NULL) {
361 			error = ENOMEM;
362 			goto out;
363 		}
364 		curr_freq->level = sc->curr_level;
365 		curr_freq->priority = sc->curr_priority;
366 		SLIST_INSERT_HEAD(&sc->saved_freq, curr_freq, link);
367 	}
368 	sc->curr_level = *level;
369 	sc->curr_priority = priority;
370 
371 	/* If we were restoring a saved state, reset it to "unused". */
372 	if (saved_freq != NULL) {
373 		CF_DEBUG("resetting saved level\n");
374 		sc->curr_level.total_set.freq = CPUFREQ_VAL_UNKNOWN;
375 		SLIST_REMOVE_HEAD(&sc->saved_freq, link);
376 		free(saved_freq, M_TEMP);
377 	}
378 
379 out:
380 	CF_MTX_UNLOCK(&sc->lock);
381 	if (error && set)
382 		device_printf(set->dev, "set freq failed, err %d\n", error);
383 	return (error);
384 }
385 
386 static int
387 cf_get_method(device_t dev, struct cf_level *level)
388 {
389 	struct cpufreq_softc *sc;
390 	struct cf_level *levels;
391 	struct cf_setting *curr_set, set;
392 	struct pcpu *pc;
393 	device_t *devs;
394 	int count, error, i, numdevs;
395 	uint64_t rate;
396 
397 	sc = device_get_softc(dev);
398 	error = 0;
399 	levels = NULL;
400 
401 	/* If we already know the current frequency, we're done. */
402 	CF_MTX_LOCK(&sc->lock);
403 	curr_set = &sc->curr_level.total_set;
404 	if (curr_set->freq != CPUFREQ_VAL_UNKNOWN) {
405 		CF_DEBUG("get returning known freq %d\n", curr_set->freq);
406 		goto out;
407 	}
408 	CF_MTX_UNLOCK(&sc->lock);
409 
410 	/*
411 	 * We need to figure out the current level.  Loop through every
412 	 * driver, getting the current setting.  Then, attempt to get a best
413 	 * match of settings against each level.
414 	 */
415 	count = CF_MAX_LEVELS;
416 	levels = malloc(count * sizeof(*levels), M_TEMP, M_NOWAIT);
417 	if (levels == NULL)
418 		return (ENOMEM);
419 	error = CPUFREQ_LEVELS(sc->dev, levels, &count);
420 	if (error) {
421 		if (error == E2BIG)
422 			printf("cpufreq: need to increase CF_MAX_LEVELS\n");
423 		free(levels, M_TEMP);
424 		return (error);
425 	}
426 	error = device_get_children(device_get_parent(dev), &devs, &numdevs);
427 	if (error) {
428 		free(levels, M_TEMP);
429 		return (error);
430 	}
431 
432 	/*
433 	 * Reacquire the lock and search for the given level.
434 	 *
435 	 * XXX Note: this is not quite right since we really need to go
436 	 * through each level and compare both absolute and relative
437 	 * settings for each driver in the system before making a match.
438 	 * The estimation code below catches this case though.
439 	 */
440 	CF_MTX_LOCK(&sc->lock);
441 	for (i = 0; i < numdevs && curr_set->freq == CPUFREQ_VAL_UNKNOWN; i++) {
442 		if (!device_is_attached(devs[i]))
443 			continue;
444 		error = CPUFREQ_DRV_GET(devs[i], &set);
445 		if (error)
446 			continue;
447 		for (i = 0; i < count; i++) {
448 			if (CPUFREQ_CMP(set.freq, levels[i].total_set.freq)) {
449 				sc->curr_level = levels[i];
450 				break;
451 			}
452 		}
453 	}
454 	free(devs, M_TEMP);
455 	if (curr_set->freq != CPUFREQ_VAL_UNKNOWN) {
456 		CF_DEBUG("get matched freq %d from drivers\n", curr_set->freq);
457 		goto out;
458 	}
459 
460 	/*
461 	 * We couldn't find an exact match, so attempt to estimate and then
462 	 * match against a level.
463 	 */
464 	pc = cpu_get_pcpu(dev);
465 	if (pc == NULL) {
466 		error = ENXIO;
467 		goto out;
468 	}
469 	cpu_est_clockrate(pc->pc_cpuid, &rate);
470 	rate /= 1000000;
471 	for (i = 0; i < count; i++) {
472 		if (CPUFREQ_CMP(rate, levels[i].total_set.freq)) {
473 			sc->curr_level = levels[i];
474 			CF_DEBUG("get estimated freq %d\n", curr_set->freq);
475 			break;
476 		}
477 	}
478 
479 out:
480 	if (error == 0)
481 		*level = sc->curr_level;
482 
483 	CF_MTX_UNLOCK(&sc->lock);
484 	if (levels)
485 		free(levels, M_TEMP);
486 	return (error);
487 }
488 
489 static int
490 cf_levels_method(device_t dev, struct cf_level *levels, int *count)
491 {
492 	struct cf_setting_array *set_arr;
493 	struct cf_setting_lst rel_sets;
494 	struct cpufreq_softc *sc;
495 	struct cf_level *lev;
496 	struct cf_setting *sets;
497 	struct pcpu *pc;
498 	device_t *devs;
499 	int error, i, numdevs, set_count, type;
500 	uint64_t rate;
501 
502 	if (levels == NULL || count == NULL)
503 		return (EINVAL);
504 
505 	TAILQ_INIT(&rel_sets);
506 	sc = device_get_softc(dev);
507 	error = device_get_children(device_get_parent(dev), &devs, &numdevs);
508 	if (error)
509 		return (error);
510 	sets = malloc(MAX_SETTINGS * sizeof(*sets), M_TEMP, M_NOWAIT);
511 	if (sets == NULL) {
512 		free(devs, M_TEMP);
513 		return (ENOMEM);
514 	}
515 
516 	/* Get settings from all cpufreq drivers. */
517 	CF_MTX_LOCK(&sc->lock);
518 	for (i = 0; i < numdevs; i++) {
519 		/* Skip devices that aren't ready. */
520 		if (!device_is_attached(devs[i]))
521 			continue;
522 
523 		/*
524 		 * Get settings, skipping drivers that offer no settings or
525 		 * provide settings for informational purposes only.
526 		 */
527 		error = CPUFREQ_DRV_TYPE(devs[i], &type);
528 		if (error || (type & CPUFREQ_FLAG_INFO_ONLY)) {
529 			if (error == 0) {
530 				CF_DEBUG("skipping info-only driver %s\n",
531 				    device_get_nameunit(devs[i]));
532 			}
533 			continue;
534 		}
535 		set_count = MAX_SETTINGS;
536 		error = CPUFREQ_DRV_SETTINGS(devs[i], sets, &set_count);
537 		if (error || set_count == 0)
538 			continue;
539 
540 		/* Add the settings to our absolute/relative lists. */
541 		switch (type & CPUFREQ_TYPE_MASK) {
542 		case CPUFREQ_TYPE_ABSOLUTE:
543 			error = cpufreq_insert_abs(sc, sets, set_count);
544 			break;
545 		case CPUFREQ_TYPE_RELATIVE:
546 			CF_DEBUG("adding %d relative settings\n", set_count);
547 			set_arr = malloc(sizeof(*set_arr), M_TEMP, M_NOWAIT);
548 			if (set_arr == NULL) {
549 				error = ENOMEM;
550 				goto out;
551 			}
552 			bcopy(sets, set_arr->sets, set_count * sizeof(*sets));
553 			set_arr->count = set_count;
554 			TAILQ_INSERT_TAIL(&rel_sets, set_arr, link);
555 			break;
556 		default:
557 			error = EINVAL;
558 		}
559 		if (error)
560 			goto out;
561 	}
562 
563 	/*
564 	 * If there are no absolute levels, create a fake one at 100%.  We
565 	 * then cache the clockrate for later use as our base frequency.
566 	 *
567 	 * XXX This assumes that the first time through, if we only have
568 	 * relative drivers, the CPU is currently running at 100%.
569 	 */
570 	if (TAILQ_EMPTY(&sc->all_levels)) {
571 		if (sc->max_mhz == CPUFREQ_VAL_UNKNOWN) {
572 			pc = cpu_get_pcpu(dev);
573 			cpu_est_clockrate(pc->pc_cpuid, &rate);
574 			sc->max_mhz = rate / 1000000;
575 		}
576 		memset(&sets[0], CPUFREQ_VAL_UNKNOWN, sizeof(*sets));
577 		sets[0].freq = sc->max_mhz;
578 		sets[0].dev = NULL;
579 		error = cpufreq_insert_abs(sc, sets, 1);
580 		if (error)
581 			goto out;
582 	}
583 
584 	/* Create a combined list of absolute + relative levels. */
585 	TAILQ_FOREACH(set_arr, &rel_sets, link)
586 		cpufreq_expand_set(sc, set_arr);
587 
588 	/* If the caller doesn't have enough space, return the actual count. */
589 	if (sc->all_count > *count) {
590 		*count = sc->all_count;
591 		error = E2BIG;
592 		goto out;
593 	}
594 
595 	/* Finally, output the list of levels. */
596 	i = 0;
597 	TAILQ_FOREACH(lev, &sc->all_levels, link) {
598 		/* Skip levels that have a frequency that is too low. */
599 		if (lev->total_set.freq < cf_lowest_freq) {
600 			sc->all_count--;
601 			continue;
602 		}
603 
604 		levels[i] = *lev;
605 		i++;
606 	}
607 	*count = sc->all_count;
608 	error = 0;
609 
610 out:
611 	/* Clear all levels since we regenerate them each time. */
612 	while ((lev = TAILQ_FIRST(&sc->all_levels)) != NULL) {
613 		TAILQ_REMOVE(&sc->all_levels, lev, link);
614 		free(lev, M_TEMP);
615 	}
616 	sc->all_count = 0;
617 
618 	CF_MTX_UNLOCK(&sc->lock);
619 	while ((set_arr = TAILQ_FIRST(&rel_sets)) != NULL) {
620 		TAILQ_REMOVE(&rel_sets, set_arr, link);
621 		free(set_arr, M_TEMP);
622 	}
623 	free(devs, M_TEMP);
624 	free(sets, M_TEMP);
625 	return (error);
626 }
627 
628 /*
629  * Create levels for an array of absolute settings and insert them in
630  * sorted order in the specified list.
631  */
632 static int
633 cpufreq_insert_abs(struct cpufreq_softc *sc, struct cf_setting *sets,
634     int count)
635 {
636 	struct cf_level_lst *list;
637 	struct cf_level *level, *search;
638 	int i;
639 
640 	CF_MTX_ASSERT(&sc->lock);
641 
642 	list = &sc->all_levels;
643 	for (i = 0; i < count; i++) {
644 		level = malloc(sizeof(*level), M_TEMP, M_NOWAIT | M_ZERO);
645 		if (level == NULL)
646 			return (ENOMEM);
647 		level->abs_set = sets[i];
648 		level->total_set = sets[i];
649 		level->total_set.dev = NULL;
650 		sc->all_count++;
651 
652 		if (TAILQ_EMPTY(list)) {
653 			CF_DEBUG("adding abs setting %d at head\n",
654 			    sets[i].freq);
655 			TAILQ_INSERT_HEAD(list, level, link);
656 			continue;
657 		}
658 
659 		TAILQ_FOREACH_REVERSE(search, list, cf_level_lst, link) {
660 			if (sets[i].freq <= search->total_set.freq) {
661 				CF_DEBUG("adding abs setting %d after %d\n",
662 				    sets[i].freq, search->total_set.freq);
663 				TAILQ_INSERT_AFTER(list, search, level, link);
664 				break;
665 			}
666 		}
667 	}
668 	return (0);
669 }
670 
671 /*
672  * Expand a group of relative settings, creating derived levels from them.
673  */
674 static int
675 cpufreq_expand_set(struct cpufreq_softc *sc, struct cf_setting_array *set_arr)
676 {
677 	struct cf_level *fill, *search;
678 	struct cf_setting *set;
679 	int i;
680 
681 	CF_MTX_ASSERT(&sc->lock);
682 
683 	/*
684 	 * Walk the set of all existing levels in reverse.  This is so we
685 	 * create derived states from the lowest absolute settings first
686 	 * and discard duplicates created from higher absolute settings.
687 	 * For instance, a level of 50 Mhz derived from 100 Mhz + 50% is
688 	 * preferable to 200 Mhz + 25% because absolute settings are more
689 	 * efficient since they often change the voltage as well.
690 	 */
691 	TAILQ_FOREACH_REVERSE(search, &sc->all_levels, cf_level_lst, link) {
692 		/* Add each setting to the level, duplicating if necessary. */
693 		for (i = 0; i < set_arr->count; i++) {
694 			set = &set_arr->sets[i];
695 
696 			/*
697 			 * If this setting is less than 100%, split the level
698 			 * into two and add this setting to the new level.
699 			 */
700 			fill = search;
701 			if (set->freq < 10000) {
702 				fill = cpufreq_dup_set(sc, search, set);
703 
704 				/*
705 				 * The new level was a duplicate of an existing
706 				 * level or its absolute setting is too high
707 				 * so we freed it.  For example, we discard a
708 				 * derived level of 1000 MHz/25% if a level
709 				 * of 500 MHz/100% already exists.
710 				 */
711 				if (fill == NULL)
712 					break;
713 			}
714 
715 			/* Add this setting to the existing or new level. */
716 			KASSERT(fill->rel_count < MAX_SETTINGS,
717 			    ("cpufreq: too many relative drivers (%d)",
718 			    MAX_SETTINGS));
719 			fill->rel_set[fill->rel_count] = *set;
720 			fill->rel_count++;
721 			CF_DEBUG(
722 			"expand set added rel setting %d%% to %d level\n",
723 			    set->freq / 100, fill->total_set.freq);
724 		}
725 	}
726 
727 	return (0);
728 }
729 
730 static struct cf_level *
731 cpufreq_dup_set(struct cpufreq_softc *sc, struct cf_level *dup,
732     struct cf_setting *set)
733 {
734 	struct cf_level_lst *list;
735 	struct cf_level *fill, *itr;
736 	struct cf_setting *fill_set, *itr_set;
737 	int i;
738 
739 	CF_MTX_ASSERT(&sc->lock);
740 
741 	/*
742 	 * Create a new level, copy it from the old one, and update the
743 	 * total frequency and power by the percentage specified in the
744 	 * relative setting.
745 	 */
746 	fill = malloc(sizeof(*fill), M_TEMP, M_NOWAIT);
747 	if (fill == NULL)
748 		return (NULL);
749 	*fill = *dup;
750 	fill_set = &fill->total_set;
751 	fill_set->freq =
752 	    ((uint64_t)fill_set->freq * set->freq) / 10000;
753 	if (fill_set->power != CPUFREQ_VAL_UNKNOWN) {
754 		fill_set->power = ((uint64_t)fill_set->power * set->freq)
755 		    / 10000;
756 	}
757 	if (set->lat != CPUFREQ_VAL_UNKNOWN) {
758 		if (fill_set->lat != CPUFREQ_VAL_UNKNOWN)
759 			fill_set->lat += set->lat;
760 		else
761 			fill_set->lat = set->lat;
762 	}
763 	CF_DEBUG("dup set considering derived setting %d\n", fill_set->freq);
764 
765 	/*
766 	 * If we copied an old level that we already modified (say, at 100%),
767 	 * we need to remove that setting before adding this one.  Since we
768 	 * process each setting array in order, we know any settings for this
769 	 * driver will be found at the end.
770 	 */
771 	for (i = fill->rel_count; i != 0; i--) {
772 		if (fill->rel_set[i - 1].dev != set->dev)
773 			break;
774 		CF_DEBUG("removed last relative driver: %s\n",
775 		    device_get_nameunit(set->dev));
776 		fill->rel_count--;
777 	}
778 
779 	/*
780 	 * Insert the new level in sorted order.  If it is a duplicate of an
781 	 * existing level (1) or has an absolute setting higher than the
782 	 * existing level (2), do not add it.  We can do this since any such
783 	 * level is guaranteed use less power.  For example (1), a level with
784 	 * one absolute setting of 800 Mhz uses less power than one composed
785 	 * of an absolute setting of 1600 Mhz and a relative setting at 50%.
786 	 * Also for example (2), a level of 800 Mhz/75% is preferable to
787 	 * 1600 Mhz/25% even though the latter has a lower total frequency.
788 	 */
789 	list = &sc->all_levels;
790 	KASSERT(!TAILQ_EMPTY(list), ("all levels list empty in dup set"));
791 	TAILQ_FOREACH_REVERSE(itr, list, cf_level_lst, link) {
792 		itr_set = &itr->total_set;
793 		if (CPUFREQ_CMP(fill_set->freq, itr_set->freq)) {
794 			CF_DEBUG("dup set rejecting %d (dupe)\n",
795 			    fill_set->freq);
796 			itr = NULL;
797 			break;
798 		} else if (fill_set->freq < itr_set->freq) {
799 			if (fill->abs_set.freq <= itr->abs_set.freq) {
800 				CF_DEBUG(
801 			"dup done, inserting new level %d after %d\n",
802 				    fill_set->freq, itr_set->freq);
803 				TAILQ_INSERT_AFTER(list, itr, fill, link);
804 				sc->all_count++;
805 			} else {
806 				CF_DEBUG("dup set rejecting %d (abs too big)\n",
807 				    fill_set->freq);
808 				itr = NULL;
809 			}
810 			break;
811 		}
812 	}
813 
814 	/* We didn't find a good place for this new level so free it. */
815 	if (itr == NULL) {
816 		CF_DEBUG("dup set freeing new level %d (not optimal)\n",
817 		    fill_set->freq);
818 		free(fill, M_TEMP);
819 		fill = NULL;
820 	}
821 
822 	return (fill);
823 }
824 
825 static int
826 cpufreq_curr_sysctl(SYSCTL_HANDLER_ARGS)
827 {
828 	struct cpufreq_softc *sc;
829 	struct cf_level *levels;
830 	int count, devcount, error, freq, i, n;
831 	device_t *devs;
832 
833 	devs = NULL;
834 	sc = oidp->oid_arg1;
835 	levels = malloc(CF_MAX_LEVELS * sizeof(*levels), M_TEMP, M_NOWAIT);
836 	if (levels == NULL)
837 		return (ENOMEM);
838 
839 	error = CPUFREQ_GET(sc->dev, &levels[0]);
840 	if (error)
841 		goto out;
842 	freq = levels[0].total_set.freq;
843 	error = sysctl_handle_int(oidp, &freq, 0, req);
844 	if (error != 0 || req->newptr == NULL)
845 		goto out;
846 
847 	/*
848 	 * While we only call cpufreq_get() on one device (assuming all
849 	 * CPUs have equal levels), we call cpufreq_set() on all CPUs.
850 	 * This is needed for some MP systems.
851 	 */
852 	error = devclass_get_devices(cpufreq_dc, &devs, &devcount);
853 	if (error)
854 		goto out;
855 	for (n = 0; n < devcount; n++) {
856 		count = CF_MAX_LEVELS;
857 		error = CPUFREQ_LEVELS(devs[n], levels, &count);
858 		if (error) {
859 			if (error == E2BIG)
860 				printf(
861 			"cpufreq: need to increase CF_MAX_LEVELS\n");
862 			break;
863 		}
864 		for (i = 0; i < count; i++) {
865 			if (CPUFREQ_CMP(levels[i].total_set.freq, freq)) {
866 				error = CPUFREQ_SET(devs[n], &levels[i],
867 				    CPUFREQ_PRIO_USER);
868 				break;
869 			}
870 		}
871 		if (i == count) {
872 			error = EINVAL;
873 			break;
874 		}
875 	}
876 
877 out:
878 	if (devs)
879 		free(devs, M_TEMP);
880 	if (levels)
881 		free(levels, M_TEMP);
882 	return (error);
883 }
884 
885 static int
886 cpufreq_levels_sysctl(SYSCTL_HANDLER_ARGS)
887 {
888 	struct cpufreq_softc *sc;
889 	struct cf_level *levels;
890 	struct cf_setting *set;
891 	struct sbuf sb;
892 	int count, error, i;
893 
894 	sc = oidp->oid_arg1;
895 	sbuf_new(&sb, NULL, 128, SBUF_AUTOEXTEND);
896 
897 	/* Get settings from the device and generate the output string. */
898 	count = CF_MAX_LEVELS;
899 	levels = malloc(count * sizeof(*levels), M_TEMP, M_NOWAIT);
900 	if (levels == NULL)
901 		return (ENOMEM);
902 	error = CPUFREQ_LEVELS(sc->dev, levels, &count);
903 	if (error) {
904 		if (error == E2BIG)
905 			printf("cpufreq: need to increase CF_MAX_LEVELS\n");
906 		goto out;
907 	}
908 	if (count) {
909 		for (i = 0; i < count; i++) {
910 			set = &levels[i].total_set;
911 			sbuf_printf(&sb, "%d/%d ", set->freq, set->power);
912 		}
913 	} else
914 		sbuf_cpy(&sb, "0");
915 	sbuf_trim(&sb);
916 	sbuf_finish(&sb);
917 	error = sysctl_handle_string(oidp, sbuf_data(&sb), sbuf_len(&sb), req);
918 
919 out:
920 	free(levels, M_TEMP);
921 	sbuf_delete(&sb);
922 	return (error);
923 }
924 
925 static int
926 cpufreq_settings_sysctl(SYSCTL_HANDLER_ARGS)
927 {
928 	device_t dev;
929 	struct cf_setting *sets;
930 	struct sbuf sb;
931 	int error, i, set_count;
932 
933 	dev = oidp->oid_arg1;
934 	sbuf_new(&sb, NULL, 128, SBUF_AUTOEXTEND);
935 
936 	/* Get settings from the device and generate the output string. */
937 	set_count = MAX_SETTINGS;
938 	sets = malloc(set_count * sizeof(*sets), M_TEMP, M_NOWAIT);
939 	if (sets == NULL)
940 		return (ENOMEM);
941 	error = CPUFREQ_DRV_SETTINGS(dev, sets, &set_count);
942 	if (error)
943 		goto out;
944 	if (set_count) {
945 		for (i = 0; i < set_count; i++)
946 			sbuf_printf(&sb, "%d/%d ", sets[i].freq, sets[i].power);
947 	} else
948 		sbuf_cpy(&sb, "0");
949 	sbuf_trim(&sb);
950 	sbuf_finish(&sb);
951 	error = sysctl_handle_string(oidp, sbuf_data(&sb), sbuf_len(&sb), req);
952 
953 out:
954 	free(sets, M_TEMP);
955 	sbuf_delete(&sb);
956 	return (error);
957 }
958 
959 int
960 cpufreq_register(device_t dev)
961 {
962 	struct cpufreq_softc *sc;
963 	device_t cf_dev, cpu_dev;
964 
965 	/* Add a sysctl to get each driver's settings separately. */
966 	SYSCTL_ADD_PROC(device_get_sysctl_ctx(dev),
967 	    SYSCTL_CHILDREN(device_get_sysctl_tree(dev)),
968 	    OID_AUTO, "freq_settings", CTLTYPE_STRING | CTLFLAG_RD, dev, 0,
969 	    cpufreq_settings_sysctl, "A", "CPU frequency driver settings");
970 
971 	/*
972 	 * Add only one cpufreq device to each CPU.  Currently, all CPUs
973 	 * must offer the same levels and be switched at the same time.
974 	 */
975 	cpu_dev = device_get_parent(dev);
976 	if ((cf_dev = device_find_child(cpu_dev, "cpufreq", -1))) {
977 		sc = device_get_softc(cf_dev);
978 		sc->max_mhz = CPUFREQ_VAL_UNKNOWN;
979 		return (0);
980 	}
981 
982 	/* Add the child device and possibly sysctls. */
983 	cf_dev = BUS_ADD_CHILD(cpu_dev, 0, "cpufreq", -1);
984 	if (cf_dev == NULL)
985 		return (ENOMEM);
986 	device_quiet(cf_dev);
987 
988 	return (device_probe_and_attach(cf_dev));
989 }
990 
991 int
992 cpufreq_unregister(device_t dev)
993 {
994 	device_t cf_dev, *devs;
995 	int cfcount, devcount, error, i, type;
996 
997 	/*
998 	 * If this is the last cpufreq child device, remove the control
999 	 * device as well.  We identify cpufreq children by calling a method
1000 	 * they support.
1001 	 */
1002 	error = device_get_children(device_get_parent(dev), &devs, &devcount);
1003 	if (error)
1004 		return (error);
1005 	cf_dev = device_find_child(device_get_parent(dev), "cpufreq", -1);
1006 	if (cf_dev == NULL) {
1007 		device_printf(dev,
1008 	"warning: cpufreq_unregister called with no cpufreq device active\n");
1009 		return (0);
1010 	}
1011 	cfcount = 0;
1012 	for (i = 0; i < devcount; i++) {
1013 		if (!device_is_attached(devs[i]))
1014 			continue;
1015 		if (CPUFREQ_DRV_TYPE(devs[i], &type) == 0)
1016 			cfcount++;
1017 	}
1018 	if (cfcount <= 1)
1019 		device_delete_child(device_get_parent(cf_dev), cf_dev);
1020 	free(devs, M_TEMP);
1021 
1022 	return (0);
1023 }
1024