1 /*
2  *  drivers/cpufreq/cpufreq_stats.c
3  *
4  *  Copyright (C) 2003-2004 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
5  *  (C) 2004 Zou Nan hai <nanhai.zou@intel.com>.
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  */
11 
12 #include <linux/kernel.h>
13 #include <linux/slab.h>
14 #include <linux/cpu.h>
15 #include <linux/sysfs.h>
16 #include <linux/cpufreq.h>
17 #include <linux/module.h>
18 #include <linux/jiffies.h>
19 #include <linux/percpu.h>
20 #include <linux/kobject.h>
21 #include <linux/spinlock.h>
22 #include <linux/notifier.h>
23 #include <asm/cputime.h>
24 
25 static spinlock_t cpufreq_stats_lock;
26 
27 struct cpufreq_stats {
28 	unsigned int cpu;
29 	unsigned int total_trans;
30 	unsigned long long last_time;
31 	unsigned int max_state;
32 	unsigned int state_num;
33 	unsigned int last_index;
34 	u64 *time_in_state;
35 	unsigned int *freq_table;
36 #ifdef CONFIG_CPU_FREQ_STAT_DETAILS
37 	unsigned int *trans_table;
38 #endif
39 };
40 
41 static DEFINE_PER_CPU(struct cpufreq_stats *, cpufreq_stats_table);
42 
43 struct cpufreq_stats_attribute {
44 	struct attribute attr;
45 	ssize_t(*show) (struct cpufreq_stats *, char *);
46 };
47 
48 static int cpufreq_stats_update(unsigned int cpu)
49 {
50 	struct cpufreq_stats *stat;
51 	unsigned long long cur_time;
52 
53 	cur_time = get_jiffies_64();
54 	spin_lock(&cpufreq_stats_lock);
55 	stat = per_cpu(cpufreq_stats_table, cpu);
56 	if (stat->time_in_state)
57 		stat->time_in_state[stat->last_index] +=
58 			cur_time - stat->last_time;
59 	stat->last_time = cur_time;
60 	spin_unlock(&cpufreq_stats_lock);
61 	return 0;
62 }
63 
64 static ssize_t show_total_trans(struct cpufreq_policy *policy, char *buf)
65 {
66 	struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, policy->cpu);
67 	if (!stat)
68 		return 0;
69 	return sprintf(buf, "%d\n",
70 			per_cpu(cpufreq_stats_table, stat->cpu)->total_trans);
71 }
72 
73 static ssize_t show_time_in_state(struct cpufreq_policy *policy, char *buf)
74 {
75 	ssize_t len = 0;
76 	int i;
77 	struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, policy->cpu);
78 	if (!stat)
79 		return 0;
80 	cpufreq_stats_update(stat->cpu);
81 	for (i = 0; i < stat->state_num; i++) {
82 		len += sprintf(buf + len, "%u %llu\n", stat->freq_table[i],
83 			(unsigned long long)
84 			cputime64_to_clock_t(stat->time_in_state[i]));
85 	}
86 	return len;
87 }
88 
89 #ifdef CONFIG_CPU_FREQ_STAT_DETAILS
90 static ssize_t show_trans_table(struct cpufreq_policy *policy, char *buf)
91 {
92 	ssize_t len = 0;
93 	int i, j;
94 
95 	struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, policy->cpu);
96 	if (!stat)
97 		return 0;
98 	cpufreq_stats_update(stat->cpu);
99 	len += snprintf(buf + len, PAGE_SIZE - len, "   From  :    To\n");
100 	len += snprintf(buf + len, PAGE_SIZE - len, "         : ");
101 	for (i = 0; i < stat->state_num; i++) {
102 		if (len >= PAGE_SIZE)
103 			break;
104 		len += snprintf(buf + len, PAGE_SIZE - len, "%9u ",
105 				stat->freq_table[i]);
106 	}
107 	if (len >= PAGE_SIZE)
108 		return PAGE_SIZE;
109 
110 	len += snprintf(buf + len, PAGE_SIZE - len, "\n");
111 
112 	for (i = 0; i < stat->state_num; i++) {
113 		if (len >= PAGE_SIZE)
114 			break;
115 
116 		len += snprintf(buf + len, PAGE_SIZE - len, "%9u: ",
117 				stat->freq_table[i]);
118 
119 		for (j = 0; j < stat->state_num; j++) {
120 			if (len >= PAGE_SIZE)
121 				break;
122 			len += snprintf(buf + len, PAGE_SIZE - len, "%9u ",
123 					stat->trans_table[i*stat->max_state+j]);
124 		}
125 		if (len >= PAGE_SIZE)
126 			break;
127 		len += snprintf(buf + len, PAGE_SIZE - len, "\n");
128 	}
129 	if (len >= PAGE_SIZE)
130 		return PAGE_SIZE;
131 	return len;
132 }
133 cpufreq_freq_attr_ro(trans_table);
134 #endif
135 
136 cpufreq_freq_attr_ro(total_trans);
137 cpufreq_freq_attr_ro(time_in_state);
138 
139 static struct attribute *default_attrs[] = {
140 	&total_trans.attr,
141 	&time_in_state.attr,
142 #ifdef CONFIG_CPU_FREQ_STAT_DETAILS
143 	&trans_table.attr,
144 #endif
145 	NULL
146 };
147 static struct attribute_group stats_attr_group = {
148 	.attrs = default_attrs,
149 	.name = "stats"
150 };
151 
152 static int freq_table_get_index(struct cpufreq_stats *stat, unsigned int freq)
153 {
154 	int index;
155 	for (index = 0; index < stat->max_state; index++)
156 		if (stat->freq_table[index] == freq)
157 			return index;
158 	return -1;
159 }
160 
161 /* should be called late in the CPU removal sequence so that the stats
162  * memory is still available in case someone tries to use it.
163  */
164 static void cpufreq_stats_free_table(unsigned int cpu)
165 {
166 	struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, cpu);
167 
168 	if (stat) {
169 		pr_debug("%s: Free stat table\n", __func__);
170 		kfree(stat->time_in_state);
171 		kfree(stat);
172 		per_cpu(cpufreq_stats_table, cpu) = NULL;
173 	}
174 }
175 
176 /* must be called early in the CPU removal sequence (before
177  * cpufreq_remove_dev) so that policy is still valid.
178  */
179 static void cpufreq_stats_free_sysfs(unsigned int cpu)
180 {
181 	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
182 
183 	if (!policy)
184 		return;
185 
186 	if (!cpufreq_frequency_get_table(cpu))
187 		goto put_ref;
188 
189 	if (!policy_is_shared(policy)) {
190 		pr_debug("%s: Free sysfs stat\n", __func__);
191 		sysfs_remove_group(&policy->kobj, &stats_attr_group);
192 	}
193 
194 put_ref:
195 	cpufreq_cpu_put(policy);
196 }
197 
198 static int cpufreq_stats_create_table(struct cpufreq_policy *policy,
199 		struct cpufreq_frequency_table *table)
200 {
201 	unsigned int i, j, count = 0, ret = 0;
202 	struct cpufreq_stats *stat;
203 	struct cpufreq_policy *data;
204 	unsigned int alloc_size;
205 	unsigned int cpu = policy->cpu;
206 	if (per_cpu(cpufreq_stats_table, cpu))
207 		return -EBUSY;
208 	stat = kzalloc(sizeof(struct cpufreq_stats), GFP_KERNEL);
209 	if ((stat) == NULL)
210 		return -ENOMEM;
211 
212 	data = cpufreq_cpu_get(cpu);
213 	if (data == NULL) {
214 		ret = -EINVAL;
215 		goto error_get_fail;
216 	}
217 
218 	ret = sysfs_create_group(&data->kobj, &stats_attr_group);
219 	if (ret)
220 		goto error_out;
221 
222 	stat->cpu = cpu;
223 	per_cpu(cpufreq_stats_table, cpu) = stat;
224 
225 	for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
226 		unsigned int freq = table[i].frequency;
227 		if (freq == CPUFREQ_ENTRY_INVALID)
228 			continue;
229 		count++;
230 	}
231 
232 	alloc_size = count * sizeof(int) + count * sizeof(u64);
233 
234 #ifdef CONFIG_CPU_FREQ_STAT_DETAILS
235 	alloc_size += count * count * sizeof(int);
236 #endif
237 	stat->max_state = count;
238 	stat->time_in_state = kzalloc(alloc_size, GFP_KERNEL);
239 	if (!stat->time_in_state) {
240 		ret = -ENOMEM;
241 		goto error_out;
242 	}
243 	stat->freq_table = (unsigned int *)(stat->time_in_state + count);
244 
245 #ifdef CONFIG_CPU_FREQ_STAT_DETAILS
246 	stat->trans_table = stat->freq_table + count;
247 #endif
248 	j = 0;
249 	for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
250 		unsigned int freq = table[i].frequency;
251 		if (freq == CPUFREQ_ENTRY_INVALID)
252 			continue;
253 		if (freq_table_get_index(stat, freq) == -1)
254 			stat->freq_table[j++] = freq;
255 	}
256 	stat->state_num = j;
257 	spin_lock(&cpufreq_stats_lock);
258 	stat->last_time = get_jiffies_64();
259 	stat->last_index = freq_table_get_index(stat, policy->cur);
260 	spin_unlock(&cpufreq_stats_lock);
261 	cpufreq_cpu_put(data);
262 	return 0;
263 error_out:
264 	cpufreq_cpu_put(data);
265 error_get_fail:
266 	kfree(stat);
267 	per_cpu(cpufreq_stats_table, cpu) = NULL;
268 	return ret;
269 }
270 
271 static void cpufreq_stats_update_policy_cpu(struct cpufreq_policy *policy)
272 {
273 	struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table,
274 			policy->last_cpu);
275 
276 	pr_debug("Updating stats_table for new_cpu %u from last_cpu %u\n",
277 			policy->cpu, policy->last_cpu);
278 	per_cpu(cpufreq_stats_table, policy->cpu) = per_cpu(cpufreq_stats_table,
279 			policy->last_cpu);
280 	per_cpu(cpufreq_stats_table, policy->last_cpu) = NULL;
281 	stat->cpu = policy->cpu;
282 }
283 
284 static int cpufreq_stat_notifier_policy(struct notifier_block *nb,
285 		unsigned long val, void *data)
286 {
287 	int ret;
288 	struct cpufreq_policy *policy = data;
289 	struct cpufreq_frequency_table *table;
290 	unsigned int cpu = policy->cpu;
291 
292 	if (val == CPUFREQ_UPDATE_POLICY_CPU) {
293 		cpufreq_stats_update_policy_cpu(policy);
294 		return 0;
295 	}
296 
297 	if (val != CPUFREQ_NOTIFY)
298 		return 0;
299 	table = cpufreq_frequency_get_table(cpu);
300 	if (!table)
301 		return 0;
302 	ret = cpufreq_stats_create_table(policy, table);
303 	if (ret)
304 		return ret;
305 	return 0;
306 }
307 
308 static int cpufreq_stat_notifier_trans(struct notifier_block *nb,
309 		unsigned long val, void *data)
310 {
311 	struct cpufreq_freqs *freq = data;
312 	struct cpufreq_stats *stat;
313 	int old_index, new_index;
314 
315 	if (val != CPUFREQ_POSTCHANGE)
316 		return 0;
317 
318 	stat = per_cpu(cpufreq_stats_table, freq->cpu);
319 	if (!stat)
320 		return 0;
321 
322 	old_index = stat->last_index;
323 	new_index = freq_table_get_index(stat, freq->new);
324 
325 	/* We can't do stat->time_in_state[-1]= .. */
326 	if (old_index == -1 || new_index == -1)
327 		return 0;
328 
329 	cpufreq_stats_update(freq->cpu);
330 
331 	if (old_index == new_index)
332 		return 0;
333 
334 	spin_lock(&cpufreq_stats_lock);
335 	stat->last_index = new_index;
336 #ifdef CONFIG_CPU_FREQ_STAT_DETAILS
337 	stat->trans_table[old_index * stat->max_state + new_index]++;
338 #endif
339 	stat->total_trans++;
340 	spin_unlock(&cpufreq_stats_lock);
341 	return 0;
342 }
343 
344 static int cpufreq_stat_cpu_callback(struct notifier_block *nfb,
345 					       unsigned long action,
346 					       void *hcpu)
347 {
348 	unsigned int cpu = (unsigned long)hcpu;
349 
350 	switch (action) {
351 	case CPU_ONLINE:
352 	case CPU_ONLINE_FROZEN:
353 		cpufreq_update_policy(cpu);
354 		break;
355 	case CPU_DOWN_PREPARE:
356 	case CPU_DOWN_PREPARE_FROZEN:
357 		cpufreq_stats_free_sysfs(cpu);
358 		break;
359 	case CPU_DEAD:
360 	case CPU_DEAD_FROZEN:
361 		cpufreq_stats_free_table(cpu);
362 		break;
363 	}
364 	return NOTIFY_OK;
365 }
366 
367 /* priority=1 so this will get called before cpufreq_remove_dev */
368 static struct notifier_block cpufreq_stat_cpu_notifier __refdata = {
369 	.notifier_call = cpufreq_stat_cpu_callback,
370 	.priority = 1,
371 };
372 
373 static struct notifier_block notifier_policy_block = {
374 	.notifier_call = cpufreq_stat_notifier_policy
375 };
376 
377 static struct notifier_block notifier_trans_block = {
378 	.notifier_call = cpufreq_stat_notifier_trans
379 };
380 
381 static int __init cpufreq_stats_init(void)
382 {
383 	int ret;
384 	unsigned int cpu;
385 
386 	spin_lock_init(&cpufreq_stats_lock);
387 	ret = cpufreq_register_notifier(&notifier_policy_block,
388 				CPUFREQ_POLICY_NOTIFIER);
389 	if (ret)
390 		return ret;
391 
392 	register_hotcpu_notifier(&cpufreq_stat_cpu_notifier);
393 	for_each_online_cpu(cpu)
394 		cpufreq_update_policy(cpu);
395 
396 	ret = cpufreq_register_notifier(&notifier_trans_block,
397 				CPUFREQ_TRANSITION_NOTIFIER);
398 	if (ret) {
399 		cpufreq_unregister_notifier(&notifier_policy_block,
400 				CPUFREQ_POLICY_NOTIFIER);
401 		unregister_hotcpu_notifier(&cpufreq_stat_cpu_notifier);
402 		for_each_online_cpu(cpu)
403 			cpufreq_stats_free_table(cpu);
404 		return ret;
405 	}
406 
407 	return 0;
408 }
409 static void __exit cpufreq_stats_exit(void)
410 {
411 	unsigned int cpu;
412 
413 	cpufreq_unregister_notifier(&notifier_policy_block,
414 			CPUFREQ_POLICY_NOTIFIER);
415 	cpufreq_unregister_notifier(&notifier_trans_block,
416 			CPUFREQ_TRANSITION_NOTIFIER);
417 	unregister_hotcpu_notifier(&cpufreq_stat_cpu_notifier);
418 	for_each_online_cpu(cpu) {
419 		cpufreq_stats_free_table(cpu);
420 		cpufreq_stats_free_sysfs(cpu);
421 	}
422 }
423 
424 MODULE_AUTHOR("Zou Nan hai <nanhai.zou@intel.com>");
425 MODULE_DESCRIPTION("'cpufreq_stats' - A driver to export cpufreq stats "
426 				"through sysfs filesystem");
427 MODULE_LICENSE("GPL");
428 
429 module_init(cpufreq_stats_init);
430 module_exit(cpufreq_stats_exit);
431