1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Versatile Express SPC CPUFreq Interface driver
4  *
5  * Copyright (C) 2013 - 2019 ARM Ltd.
6  * Sudeep Holla <sudeep.holla@arm.com>
7  *
8  * Copyright (C) 2013 Linaro.
9  * Viresh Kumar <viresh.kumar@linaro.org>
10  */
11 
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13 
14 #include <linux/clk.h>
15 #include <linux/cpu.h>
16 #include <linux/cpufreq.h>
17 #include <linux/cpumask.h>
18 #include <linux/cpu_cooling.h>
19 #include <linux/device.h>
20 #include <linux/module.h>
21 #include <linux/mutex.h>
22 #include <linux/of_platform.h>
23 #include <linux/platform_device.h>
24 #include <linux/pm_opp.h>
25 #include <linux/slab.h>
26 #include <linux/topology.h>
27 #include <linux/types.h>
28 
29 /* Currently we support only two clusters */
30 #define A15_CLUSTER	0
31 #define A7_CLUSTER	1
32 #define MAX_CLUSTERS	2
33 
34 #ifdef CONFIG_BL_SWITCHER
35 #include <asm/bL_switcher.h>
36 static bool bL_switching_enabled;
37 #define is_bL_switching_enabled()	bL_switching_enabled
38 #define set_switching_enabled(x)	(bL_switching_enabled = (x))
39 #else
40 #define is_bL_switching_enabled()	false
41 #define set_switching_enabled(x)	do { } while (0)
42 #define bL_switch_request(...)		do { } while (0)
43 #define bL_switcher_put_enabled()	do { } while (0)
44 #define bL_switcher_get_enabled()	do { } while (0)
45 #endif
46 
47 #define ACTUAL_FREQ(cluster, freq)  ((cluster == A7_CLUSTER) ? freq << 1 : freq)
48 #define VIRT_FREQ(cluster, freq)    ((cluster == A7_CLUSTER) ? freq >> 1 : freq)
49 
50 static struct thermal_cooling_device *cdev[MAX_CLUSTERS];
51 static struct clk *clk[MAX_CLUSTERS];
52 static struct cpufreq_frequency_table *freq_table[MAX_CLUSTERS + 1];
53 static atomic_t cluster_usage[MAX_CLUSTERS + 1];
54 
55 static unsigned int clk_big_min;	/* (Big) clock frequencies */
56 static unsigned int clk_little_max;	/* Maximum clock frequency (Little) */
57 
58 static DEFINE_PER_CPU(unsigned int, physical_cluster);
59 static DEFINE_PER_CPU(unsigned int, cpu_last_req_freq);
60 
61 static struct mutex cluster_lock[MAX_CLUSTERS];
62 
63 static inline int raw_cpu_to_cluster(int cpu)
64 {
65 	return topology_physical_package_id(cpu);
66 }
67 
68 static inline int cpu_to_cluster(int cpu)
69 {
70 	return is_bL_switching_enabled() ?
71 		MAX_CLUSTERS : raw_cpu_to_cluster(cpu);
72 }
73 
74 static unsigned int find_cluster_maxfreq(int cluster)
75 {
76 	int j;
77 	u32 max_freq = 0, cpu_freq;
78 
79 	for_each_online_cpu(j) {
80 		cpu_freq = per_cpu(cpu_last_req_freq, j);
81 
82 		if (cluster == per_cpu(physical_cluster, j) &&
83 		    max_freq < cpu_freq)
84 			max_freq = cpu_freq;
85 	}
86 
87 	return max_freq;
88 }
89 
90 static unsigned int clk_get_cpu_rate(unsigned int cpu)
91 {
92 	u32 cur_cluster = per_cpu(physical_cluster, cpu);
93 	u32 rate = clk_get_rate(clk[cur_cluster]) / 1000;
94 
95 	/* For switcher we use virtual A7 clock rates */
96 	if (is_bL_switching_enabled())
97 		rate = VIRT_FREQ(cur_cluster, rate);
98 
99 	return rate;
100 }
101 
102 static unsigned int ve_spc_cpufreq_get_rate(unsigned int cpu)
103 {
104 	if (is_bL_switching_enabled())
105 		return per_cpu(cpu_last_req_freq, cpu);
106 	else
107 		return clk_get_cpu_rate(cpu);
108 }
109 
110 static unsigned int
111 ve_spc_cpufreq_set_rate(u32 cpu, u32 old_cluster, u32 new_cluster, u32 rate)
112 {
113 	u32 new_rate, prev_rate;
114 	int ret;
115 	bool bLs = is_bL_switching_enabled();
116 
117 	mutex_lock(&cluster_lock[new_cluster]);
118 
119 	if (bLs) {
120 		prev_rate = per_cpu(cpu_last_req_freq, cpu);
121 		per_cpu(cpu_last_req_freq, cpu) = rate;
122 		per_cpu(physical_cluster, cpu) = new_cluster;
123 
124 		new_rate = find_cluster_maxfreq(new_cluster);
125 		new_rate = ACTUAL_FREQ(new_cluster, new_rate);
126 	} else {
127 		new_rate = rate;
128 	}
129 
130 	ret = clk_set_rate(clk[new_cluster], new_rate * 1000);
131 	if (!ret) {
132 		/*
133 		 * FIXME: clk_set_rate hasn't returned an error here however it
134 		 * may be that clk_change_rate failed due to hardware or
135 		 * firmware issues and wasn't able to report that due to the
136 		 * current design of the clk core layer. To work around this
137 		 * problem we will read back the clock rate and check it is
138 		 * correct. This needs to be removed once clk core is fixed.
139 		 */
140 		if (clk_get_rate(clk[new_cluster]) != new_rate * 1000)
141 			ret = -EIO;
142 	}
143 
144 	if (WARN_ON(ret)) {
145 		if (bLs) {
146 			per_cpu(cpu_last_req_freq, cpu) = prev_rate;
147 			per_cpu(physical_cluster, cpu) = old_cluster;
148 		}
149 
150 		mutex_unlock(&cluster_lock[new_cluster]);
151 
152 		return ret;
153 	}
154 
155 	mutex_unlock(&cluster_lock[new_cluster]);
156 
157 	/* Recalc freq for old cluster when switching clusters */
158 	if (old_cluster != new_cluster) {
159 		/* Switch cluster */
160 		bL_switch_request(cpu, new_cluster);
161 
162 		mutex_lock(&cluster_lock[old_cluster]);
163 
164 		/* Set freq of old cluster if there are cpus left on it */
165 		new_rate = find_cluster_maxfreq(old_cluster);
166 		new_rate = ACTUAL_FREQ(old_cluster, new_rate);
167 
168 		if (new_rate &&
169 		    clk_set_rate(clk[old_cluster], new_rate * 1000)) {
170 			pr_err("%s: clk_set_rate failed: %d, old cluster: %d\n",
171 			       __func__, ret, old_cluster);
172 		}
173 		mutex_unlock(&cluster_lock[old_cluster]);
174 	}
175 
176 	return 0;
177 }
178 
179 /* Set clock frequency */
180 static int ve_spc_cpufreq_set_target(struct cpufreq_policy *policy,
181 				     unsigned int index)
182 {
183 	u32 cpu = policy->cpu, cur_cluster, new_cluster, actual_cluster;
184 	unsigned int freqs_new;
185 
186 	cur_cluster = cpu_to_cluster(cpu);
187 	new_cluster = actual_cluster = per_cpu(physical_cluster, cpu);
188 
189 	freqs_new = freq_table[cur_cluster][index].frequency;
190 
191 	if (is_bL_switching_enabled()) {
192 		if (actual_cluster == A15_CLUSTER && freqs_new < clk_big_min)
193 			new_cluster = A7_CLUSTER;
194 		else if (actual_cluster == A7_CLUSTER &&
195 			 freqs_new > clk_little_max)
196 			new_cluster = A15_CLUSTER;
197 	}
198 
199 	return ve_spc_cpufreq_set_rate(cpu, actual_cluster, new_cluster,
200 				       freqs_new);
201 }
202 
203 static inline u32 get_table_count(struct cpufreq_frequency_table *table)
204 {
205 	int count;
206 
207 	for (count = 0; table[count].frequency != CPUFREQ_TABLE_END; count++)
208 		;
209 
210 	return count;
211 }
212 
213 /* get the minimum frequency in the cpufreq_frequency_table */
214 static inline u32 get_table_min(struct cpufreq_frequency_table *table)
215 {
216 	struct cpufreq_frequency_table *pos;
217 	u32 min_freq = ~0;
218 
219 	cpufreq_for_each_entry(pos, table)
220 		if (pos->frequency < min_freq)
221 			min_freq = pos->frequency;
222 	return min_freq;
223 }
224 
225 /* get the maximum frequency in the cpufreq_frequency_table */
226 static inline u32 get_table_max(struct cpufreq_frequency_table *table)
227 {
228 	struct cpufreq_frequency_table *pos;
229 	u32 max_freq = 0;
230 
231 	cpufreq_for_each_entry(pos, table)
232 		if (pos->frequency > max_freq)
233 			max_freq = pos->frequency;
234 	return max_freq;
235 }
236 
237 static bool search_frequency(struct cpufreq_frequency_table *table, int size,
238 			     unsigned int freq)
239 {
240 	int count;
241 
242 	for (count = 0; count < size; count++) {
243 		if (table[count].frequency == freq)
244 			return true;
245 	}
246 
247 	return false;
248 }
249 
250 static int merge_cluster_tables(void)
251 {
252 	int i, j, k = 0, count = 1;
253 	struct cpufreq_frequency_table *table;
254 
255 	for (i = 0; i < MAX_CLUSTERS; i++)
256 		count += get_table_count(freq_table[i]);
257 
258 	table = kcalloc(count, sizeof(*table), GFP_KERNEL);
259 	if (!table)
260 		return -ENOMEM;
261 
262 	freq_table[MAX_CLUSTERS] = table;
263 
264 	/* Add in reverse order to get freqs in increasing order */
265 	for (i = MAX_CLUSTERS - 1; i >= 0; i--, count = k) {
266 		for (j = 0; freq_table[i][j].frequency != CPUFREQ_TABLE_END;
267 		     j++) {
268 			if (i == A15_CLUSTER &&
269 			    search_frequency(table, count, freq_table[i][j].frequency))
270 				continue; /* skip duplicates */
271 			table[k++].frequency =
272 				VIRT_FREQ(i, freq_table[i][j].frequency);
273 		}
274 	}
275 
276 	table[k].driver_data = k;
277 	table[k].frequency = CPUFREQ_TABLE_END;
278 
279 	return 0;
280 }
281 
282 static void _put_cluster_clk_and_freq_table(struct device *cpu_dev,
283 					    const struct cpumask *cpumask)
284 {
285 	u32 cluster = raw_cpu_to_cluster(cpu_dev->id);
286 
287 	if (!freq_table[cluster])
288 		return;
289 
290 	clk_put(clk[cluster]);
291 	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);
292 }
293 
294 static void put_cluster_clk_and_freq_table(struct device *cpu_dev,
295 					   const struct cpumask *cpumask)
296 {
297 	u32 cluster = cpu_to_cluster(cpu_dev->id);
298 	int i;
299 
300 	if (atomic_dec_return(&cluster_usage[cluster]))
301 		return;
302 
303 	if (cluster < MAX_CLUSTERS)
304 		return _put_cluster_clk_and_freq_table(cpu_dev, cpumask);
305 
306 	for_each_present_cpu(i) {
307 		struct device *cdev = get_cpu_device(i);
308 
309 		if (!cdev)
310 			return;
311 
312 		_put_cluster_clk_and_freq_table(cdev, cpumask);
313 	}
314 
315 	/* free virtual table */
316 	kfree(freq_table[cluster]);
317 }
318 
319 static int _get_cluster_clk_and_freq_table(struct device *cpu_dev,
320 					   const struct cpumask *cpumask)
321 {
322 	u32 cluster = raw_cpu_to_cluster(cpu_dev->id);
323 	int ret;
324 
325 	if (freq_table[cluster])
326 		return 0;
327 
328 	/*
329 	 * platform specific SPC code must initialise the opp table
330 	 * so just check if the OPP count is non-zero
331 	 */
332 	ret = dev_pm_opp_get_opp_count(cpu_dev) <= 0;
333 	if (ret)
334 		goto out;
335 
336 	ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table[cluster]);
337 	if (ret)
338 		goto out;
339 
340 	clk[cluster] = clk_get(cpu_dev, NULL);
341 	if (!IS_ERR(clk[cluster]))
342 		return 0;
343 
344 	dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d, cluster: %d\n",
345 		__func__, cpu_dev->id, cluster);
346 	ret = PTR_ERR(clk[cluster]);
347 	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);
348 
349 out:
350 	dev_err(cpu_dev, "%s: Failed to get data for cluster: %d\n", __func__,
351 		cluster);
352 	return ret;
353 }
354 
355 static int get_cluster_clk_and_freq_table(struct device *cpu_dev,
356 					  const struct cpumask *cpumask)
357 {
358 	u32 cluster = cpu_to_cluster(cpu_dev->id);
359 	int i, ret;
360 
361 	if (atomic_inc_return(&cluster_usage[cluster]) != 1)
362 		return 0;
363 
364 	if (cluster < MAX_CLUSTERS) {
365 		ret = _get_cluster_clk_and_freq_table(cpu_dev, cpumask);
366 		if (ret)
367 			atomic_dec(&cluster_usage[cluster]);
368 		return ret;
369 	}
370 
371 	/*
372 	 * Get data for all clusters and fill virtual cluster with a merge of
373 	 * both
374 	 */
375 	for_each_present_cpu(i) {
376 		struct device *cdev = get_cpu_device(i);
377 
378 		if (!cdev)
379 			return -ENODEV;
380 
381 		ret = _get_cluster_clk_and_freq_table(cdev, cpumask);
382 		if (ret)
383 			goto put_clusters;
384 	}
385 
386 	ret = merge_cluster_tables();
387 	if (ret)
388 		goto put_clusters;
389 
390 	/* Assuming 2 cluster, set clk_big_min and clk_little_max */
391 	clk_big_min = get_table_min(freq_table[A15_CLUSTER]);
392 	clk_little_max = VIRT_FREQ(A7_CLUSTER,
393 				   get_table_max(freq_table[A7_CLUSTER]));
394 
395 	return 0;
396 
397 put_clusters:
398 	for_each_present_cpu(i) {
399 		struct device *cdev = get_cpu_device(i);
400 
401 		if (!cdev)
402 			return -ENODEV;
403 
404 		_put_cluster_clk_and_freq_table(cdev, cpumask);
405 	}
406 
407 	atomic_dec(&cluster_usage[cluster]);
408 
409 	return ret;
410 }
411 
412 /* Per-CPU initialization */
413 static int ve_spc_cpufreq_init(struct cpufreq_policy *policy)
414 {
415 	u32 cur_cluster = cpu_to_cluster(policy->cpu);
416 	struct device *cpu_dev;
417 	int ret;
418 
419 	cpu_dev = get_cpu_device(policy->cpu);
420 	if (!cpu_dev) {
421 		pr_err("%s: failed to get cpu%d device\n", __func__,
422 		       policy->cpu);
423 		return -ENODEV;
424 	}
425 
426 	if (cur_cluster < MAX_CLUSTERS) {
427 		int cpu;
428 
429 		dev_pm_opp_get_sharing_cpus(cpu_dev, policy->cpus);
430 
431 		for_each_cpu(cpu, policy->cpus)
432 			per_cpu(physical_cluster, cpu) = cur_cluster;
433 	} else {
434 		/* Assumption: during init, we are always running on A15 */
435 		per_cpu(physical_cluster, policy->cpu) = A15_CLUSTER;
436 	}
437 
438 	ret = get_cluster_clk_and_freq_table(cpu_dev, policy->cpus);
439 	if (ret)
440 		return ret;
441 
442 	policy->freq_table = freq_table[cur_cluster];
443 	policy->cpuinfo.transition_latency = 1000000; /* 1 ms */
444 
445 	dev_pm_opp_of_register_em(cpu_dev, policy->cpus);
446 
447 	if (is_bL_switching_enabled())
448 		per_cpu(cpu_last_req_freq, policy->cpu) =
449 						clk_get_cpu_rate(policy->cpu);
450 
451 	dev_info(cpu_dev, "%s: CPU %d initialized\n", __func__, policy->cpu);
452 	return 0;
453 }
454 
455 static int ve_spc_cpufreq_exit(struct cpufreq_policy *policy)
456 {
457 	struct device *cpu_dev;
458 	int cur_cluster = cpu_to_cluster(policy->cpu);
459 
460 	if (cur_cluster < MAX_CLUSTERS) {
461 		cpufreq_cooling_unregister(cdev[cur_cluster]);
462 		cdev[cur_cluster] = NULL;
463 	}
464 
465 	cpu_dev = get_cpu_device(policy->cpu);
466 	if (!cpu_dev) {
467 		pr_err("%s: failed to get cpu%d device\n", __func__,
468 		       policy->cpu);
469 		return -ENODEV;
470 	}
471 
472 	put_cluster_clk_and_freq_table(cpu_dev, policy->related_cpus);
473 	return 0;
474 }
475 
476 static void ve_spc_cpufreq_ready(struct cpufreq_policy *policy)
477 {
478 	int cur_cluster = cpu_to_cluster(policy->cpu);
479 
480 	/* Do not register a cpu_cooling device if we are in IKS mode */
481 	if (cur_cluster >= MAX_CLUSTERS)
482 		return;
483 
484 	cdev[cur_cluster] = of_cpufreq_cooling_register(policy);
485 }
486 
487 static struct cpufreq_driver ve_spc_cpufreq_driver = {
488 	.name			= "vexpress-spc",
489 	.flags			= CPUFREQ_STICKY |
490 					CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
491 					CPUFREQ_NEED_INITIAL_FREQ_CHECK,
492 	.verify			= cpufreq_generic_frequency_table_verify,
493 	.target_index		= ve_spc_cpufreq_set_target,
494 	.get			= ve_spc_cpufreq_get_rate,
495 	.init			= ve_spc_cpufreq_init,
496 	.exit			= ve_spc_cpufreq_exit,
497 	.ready			= ve_spc_cpufreq_ready,
498 	.attr			= cpufreq_generic_attr,
499 };
500 
501 #ifdef CONFIG_BL_SWITCHER
502 static int bL_cpufreq_switcher_notifier(struct notifier_block *nfb,
503 					unsigned long action, void *_arg)
504 {
505 	pr_debug("%s: action: %ld\n", __func__, action);
506 
507 	switch (action) {
508 	case BL_NOTIFY_PRE_ENABLE:
509 	case BL_NOTIFY_PRE_DISABLE:
510 		cpufreq_unregister_driver(&ve_spc_cpufreq_driver);
511 		break;
512 
513 	case BL_NOTIFY_POST_ENABLE:
514 		set_switching_enabled(true);
515 		cpufreq_register_driver(&ve_spc_cpufreq_driver);
516 		break;
517 
518 	case BL_NOTIFY_POST_DISABLE:
519 		set_switching_enabled(false);
520 		cpufreq_register_driver(&ve_spc_cpufreq_driver);
521 		break;
522 
523 	default:
524 		return NOTIFY_DONE;
525 	}
526 
527 	return NOTIFY_OK;
528 }
529 
530 static struct notifier_block bL_switcher_notifier = {
531 	.notifier_call = bL_cpufreq_switcher_notifier,
532 };
533 
534 static int __bLs_register_notifier(void)
535 {
536 	return bL_switcher_register_notifier(&bL_switcher_notifier);
537 }
538 
539 static int __bLs_unregister_notifier(void)
540 {
541 	return bL_switcher_unregister_notifier(&bL_switcher_notifier);
542 }
543 #else
544 static int __bLs_register_notifier(void) { return 0; }
545 static int __bLs_unregister_notifier(void) { return 0; }
546 #endif
547 
548 static int ve_spc_cpufreq_probe(struct platform_device *pdev)
549 {
550 	int ret, i;
551 
552 	set_switching_enabled(bL_switcher_get_enabled());
553 
554 	for (i = 0; i < MAX_CLUSTERS; i++)
555 		mutex_init(&cluster_lock[i]);
556 
557 	ret = cpufreq_register_driver(&ve_spc_cpufreq_driver);
558 	if (ret) {
559 		pr_info("%s: Failed registering platform driver: %s, err: %d\n",
560 			__func__, ve_spc_cpufreq_driver.name, ret);
561 	} else {
562 		ret = __bLs_register_notifier();
563 		if (ret)
564 			cpufreq_unregister_driver(&ve_spc_cpufreq_driver);
565 		else
566 			pr_info("%s: Registered platform driver: %s\n",
567 				__func__, ve_spc_cpufreq_driver.name);
568 	}
569 
570 	bL_switcher_put_enabled();
571 	return ret;
572 }
573 
574 static int ve_spc_cpufreq_remove(struct platform_device *pdev)
575 {
576 	bL_switcher_get_enabled();
577 	__bLs_unregister_notifier();
578 	cpufreq_unregister_driver(&ve_spc_cpufreq_driver);
579 	bL_switcher_put_enabled();
580 	pr_info("%s: Un-registered platform driver: %s\n", __func__,
581 		ve_spc_cpufreq_driver.name);
582 	return 0;
583 }
584 
585 static struct platform_driver ve_spc_cpufreq_platdrv = {
586 	.driver = {
587 		.name	= "vexpress-spc-cpufreq",
588 	},
589 	.probe		= ve_spc_cpufreq_probe,
590 	.remove		= ve_spc_cpufreq_remove,
591 };
592 module_platform_driver(ve_spc_cpufreq_platdrv);
593 
594 MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
595 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
596 MODULE_DESCRIPTION("Vexpress SPC ARM big LITTLE cpufreq driver");
597 MODULE_LICENSE("GPL v2");
598