1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * drivers/cpufreq/cpufreq_stats.c
4 *
5 * Copyright (C) 2003-2004 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
6 * (C) 2004 Zou Nan hai <nanhai.zou@intel.com>.
7 */
8
9 #include <linux/cpu.h>
10 #include <linux/cpufreq.h>
11 #include <linux/module.h>
12 #include <linux/sched/clock.h>
13 #include <linux/slab.h>
14
15 struct cpufreq_stats {
16 unsigned int total_trans;
17 unsigned long long last_time;
18 unsigned int max_state;
19 unsigned int state_num;
20 unsigned int last_index;
21 u64 *time_in_state;
22 unsigned int *freq_table;
23 unsigned int *trans_table;
24
25 /* Deferred reset */
26 unsigned int reset_pending;
27 unsigned long long reset_time;
28 };
29
cpufreq_stats_update(struct cpufreq_stats * stats,unsigned long long time)30 static void cpufreq_stats_update(struct cpufreq_stats *stats,
31 unsigned long long time)
32 {
33 unsigned long long cur_time = local_clock();
34
35 stats->time_in_state[stats->last_index] += cur_time - time;
36 stats->last_time = cur_time;
37 }
38
cpufreq_stats_reset_table(struct cpufreq_stats * stats)39 static void cpufreq_stats_reset_table(struct cpufreq_stats *stats)
40 {
41 unsigned int count = stats->max_state;
42
43 memset(stats->time_in_state, 0, count * sizeof(u64));
44 memset(stats->trans_table, 0, count * count * sizeof(int));
45 stats->last_time = local_clock();
46 stats->total_trans = 0;
47
48 /* Adjust for the time elapsed since reset was requested */
49 WRITE_ONCE(stats->reset_pending, 0);
50 /*
51 * Prevent the reset_time read from being reordered before the
52 * reset_pending accesses in cpufreq_stats_record_transition().
53 */
54 smp_rmb();
55 cpufreq_stats_update(stats, READ_ONCE(stats->reset_time));
56 }
57
show_total_trans(struct cpufreq_policy * policy,char * buf)58 static ssize_t show_total_trans(struct cpufreq_policy *policy, char *buf)
59 {
60 struct cpufreq_stats *stats = policy->stats;
61
62 if (READ_ONCE(stats->reset_pending))
63 return sprintf(buf, "%d\n", 0);
64 else
65 return sprintf(buf, "%u\n", stats->total_trans);
66 }
67 cpufreq_freq_attr_ro(total_trans);
68
show_time_in_state(struct cpufreq_policy * policy,char * buf)69 static ssize_t show_time_in_state(struct cpufreq_policy *policy, char *buf)
70 {
71 struct cpufreq_stats *stats = policy->stats;
72 bool pending = READ_ONCE(stats->reset_pending);
73 unsigned long long time;
74 ssize_t len = 0;
75 int i;
76
77 for (i = 0; i < stats->state_num; i++) {
78 if (pending) {
79 if (i == stats->last_index) {
80 /*
81 * Prevent the reset_time read from occurring
82 * before the reset_pending read above.
83 */
84 smp_rmb();
85 time = local_clock() - READ_ONCE(stats->reset_time);
86 } else {
87 time = 0;
88 }
89 } else {
90 time = stats->time_in_state[i];
91 if (i == stats->last_index)
92 time += local_clock() - stats->last_time;
93 }
94
95 len += sprintf(buf + len, "%u %llu\n", stats->freq_table[i],
96 nsec_to_clock_t(time));
97 }
98 return len;
99 }
100 cpufreq_freq_attr_ro(time_in_state);
101
102 /* We don't care what is written to the attribute */
store_reset(struct cpufreq_policy * policy,const char * buf,size_t count)103 static ssize_t store_reset(struct cpufreq_policy *policy, const char *buf,
104 size_t count)
105 {
106 struct cpufreq_stats *stats = policy->stats;
107
108 /*
109 * Defer resetting of stats to cpufreq_stats_record_transition() to
110 * avoid races.
111 */
112 WRITE_ONCE(stats->reset_time, local_clock());
113 /*
114 * The memory barrier below is to prevent the readers of reset_time from
115 * seeing a stale or partially updated value.
116 */
117 smp_wmb();
118 WRITE_ONCE(stats->reset_pending, 1);
119
120 return count;
121 }
122 cpufreq_freq_attr_wo(reset);
123
show_trans_table(struct cpufreq_policy * policy,char * buf)124 static ssize_t show_trans_table(struct cpufreq_policy *policy, char *buf)
125 {
126 struct cpufreq_stats *stats = policy->stats;
127 bool pending = READ_ONCE(stats->reset_pending);
128 ssize_t len = 0;
129 int i, j, count;
130
131 len += scnprintf(buf + len, PAGE_SIZE - len, " From : To\n");
132 len += scnprintf(buf + len, PAGE_SIZE - len, " : ");
133 for (i = 0; i < stats->state_num; i++) {
134 if (len >= PAGE_SIZE)
135 break;
136 len += scnprintf(buf + len, PAGE_SIZE - len, "%9u ",
137 stats->freq_table[i]);
138 }
139 if (len >= PAGE_SIZE)
140 return PAGE_SIZE;
141
142 len += scnprintf(buf + len, PAGE_SIZE - len, "\n");
143
144 for (i = 0; i < stats->state_num; i++) {
145 if (len >= PAGE_SIZE)
146 break;
147
148 len += scnprintf(buf + len, PAGE_SIZE - len, "%9u: ",
149 stats->freq_table[i]);
150
151 for (j = 0; j < stats->state_num; j++) {
152 if (len >= PAGE_SIZE)
153 break;
154
155 if (pending)
156 count = 0;
157 else
158 count = stats->trans_table[i * stats->max_state + j];
159
160 len += scnprintf(buf + len, PAGE_SIZE - len, "%9u ", count);
161 }
162 if (len >= PAGE_SIZE)
163 break;
164 len += scnprintf(buf + len, PAGE_SIZE - len, "\n");
165 }
166
167 if (len >= PAGE_SIZE) {
168 pr_warn_once("cpufreq transition table exceeds PAGE_SIZE. Disabling\n");
169 return -EFBIG;
170 }
171 return len;
172 }
173 cpufreq_freq_attr_ro(trans_table);
174
175 static struct attribute *default_attrs[] = {
176 &total_trans.attr,
177 &time_in_state.attr,
178 &reset.attr,
179 &trans_table.attr,
180 NULL
181 };
182 static const struct attribute_group stats_attr_group = {
183 .attrs = default_attrs,
184 .name = "stats"
185 };
186
freq_table_get_index(struct cpufreq_stats * stats,unsigned int freq)187 static int freq_table_get_index(struct cpufreq_stats *stats, unsigned int freq)
188 {
189 int index;
190 for (index = 0; index < stats->max_state; index++)
191 if (stats->freq_table[index] == freq)
192 return index;
193 return -1;
194 }
195
cpufreq_stats_free_table(struct cpufreq_policy * policy)196 void cpufreq_stats_free_table(struct cpufreq_policy *policy)
197 {
198 struct cpufreq_stats *stats = policy->stats;
199
200 /* Already freed */
201 if (!stats)
202 return;
203
204 pr_debug("%s: Free stats table\n", __func__);
205
206 sysfs_remove_group(&policy->kobj, &stats_attr_group);
207 kfree(stats->time_in_state);
208 kfree(stats);
209 policy->stats = NULL;
210 }
211
cpufreq_stats_create_table(struct cpufreq_policy * policy)212 void cpufreq_stats_create_table(struct cpufreq_policy *policy)
213 {
214 unsigned int i = 0, count;
215 struct cpufreq_stats *stats;
216 unsigned int alloc_size;
217 struct cpufreq_frequency_table *pos;
218
219 count = cpufreq_table_count_valid_entries(policy);
220 if (!count)
221 return;
222
223 /* stats already initialized */
224 if (policy->stats)
225 return;
226
227 stats = kzalloc(sizeof(*stats), GFP_KERNEL);
228 if (!stats)
229 return;
230
231 alloc_size = count * sizeof(int) + count * sizeof(u64);
232
233 alloc_size += count * count * sizeof(int);
234
235 /* Allocate memory for time_in_state/freq_table/trans_table in one go */
236 stats->time_in_state = kzalloc(alloc_size, GFP_KERNEL);
237 if (!stats->time_in_state)
238 goto free_stat;
239
240 stats->freq_table = (unsigned int *)(stats->time_in_state + count);
241
242 stats->trans_table = stats->freq_table + count;
243
244 stats->max_state = count;
245
246 /* Find valid-unique entries */
247 cpufreq_for_each_valid_entry(pos, policy->freq_table)
248 if (freq_table_get_index(stats, pos->frequency) == -1)
249 stats->freq_table[i++] = pos->frequency;
250
251 stats->state_num = i;
252 stats->last_time = local_clock();
253 stats->last_index = freq_table_get_index(stats, policy->cur);
254
255 policy->stats = stats;
256 if (!sysfs_create_group(&policy->kobj, &stats_attr_group))
257 return;
258
259 /* We failed, release resources */
260 policy->stats = NULL;
261 kfree(stats->time_in_state);
262 free_stat:
263 kfree(stats);
264 }
265
cpufreq_stats_record_transition(struct cpufreq_policy * policy,unsigned int new_freq)266 void cpufreq_stats_record_transition(struct cpufreq_policy *policy,
267 unsigned int new_freq)
268 {
269 struct cpufreq_stats *stats = policy->stats;
270 int old_index, new_index;
271
272 if (unlikely(!stats))
273 return;
274
275 if (unlikely(READ_ONCE(stats->reset_pending)))
276 cpufreq_stats_reset_table(stats);
277
278 old_index = stats->last_index;
279 new_index = freq_table_get_index(stats, new_freq);
280
281 /* We can't do stats->time_in_state[-1]= .. */
282 if (unlikely(old_index == -1 || new_index == -1 || old_index == new_index))
283 return;
284
285 cpufreq_stats_update(stats, stats->last_time);
286
287 stats->last_index = new_index;
288 stats->trans_table[old_index * stats->max_state + new_index]++;
289 stats->total_trans++;
290 }
291
