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