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