linux/drivers/cpufreq/cpufreq_stats.c
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   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/cpu.h>
  13#include <linux/cpufreq.h>
  14#include <linux/module.h>
  15#include <linux/slab.h>
  16#include <asm/cputime.h>
  17
  18static spinlock_t cpufreq_stats_lock;
  19
  20struct cpufreq_stats {
  21        unsigned int cpu;
  22        unsigned int total_trans;
  23        unsigned long long last_time;
  24        unsigned int max_state;
  25        unsigned int state_num;
  26        unsigned int last_index;
  27        u64 *time_in_state;
  28        unsigned int *freq_table;
  29#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
  30        unsigned int *trans_table;
  31#endif
  32};
  33
  34static DEFINE_PER_CPU(struct cpufreq_stats *, cpufreq_stats_table);
  35
  36struct cpufreq_stats_attribute {
  37        struct attribute attr;
  38        ssize_t(*show) (struct cpufreq_stats *, char *);
  39};
  40
  41static int cpufreq_stats_update(unsigned int cpu)
  42{
  43        struct cpufreq_stats *stat;
  44        unsigned long long cur_time;
  45
  46        cur_time = get_jiffies_64();
  47        spin_lock(&cpufreq_stats_lock);
  48        stat = per_cpu(cpufreq_stats_table, cpu);
  49        if (stat->time_in_state)
  50                stat->time_in_state[stat->last_index] +=
  51                        cur_time - stat->last_time;
  52        stat->last_time = cur_time;
  53        spin_unlock(&cpufreq_stats_lock);
  54        return 0;
  55}
  56
  57static ssize_t show_total_trans(struct cpufreq_policy *policy, char *buf)
  58{
  59        struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, policy->cpu);
  60        if (!stat)
  61                return 0;
  62        return sprintf(buf, "%d\n",
  63                        per_cpu(cpufreq_stats_table, stat->cpu)->total_trans);
  64}
  65
  66static ssize_t show_time_in_state(struct cpufreq_policy *policy, char *buf)
  67{
  68        ssize_t len = 0;
  69        int i;
  70        struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, policy->cpu);
  71        if (!stat)
  72                return 0;
  73        cpufreq_stats_update(stat->cpu);
  74        for (i = 0; i < stat->state_num; i++) {
  75                len += sprintf(buf + len, "%u %llu\n", stat->freq_table[i],
  76                        (unsigned long long)
  77                        jiffies_64_to_clock_t(stat->time_in_state[i]));
  78        }
  79        return len;
  80}
  81
  82#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
  83static ssize_t show_trans_table(struct cpufreq_policy *policy, char *buf)
  84{
  85        ssize_t len = 0;
  86        int i, j;
  87
  88        struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, policy->cpu);
  89        if (!stat)
  90                return 0;
  91        cpufreq_stats_update(stat->cpu);
  92        len += snprintf(buf + len, PAGE_SIZE - len, "   From  :    To\n");
  93        len += snprintf(buf + len, PAGE_SIZE - len, "         : ");
  94        for (i = 0; i < stat->state_num; i++) {
  95                if (len >= PAGE_SIZE)
  96                        break;
  97                len += snprintf(buf + len, PAGE_SIZE - len, "%9u ",
  98                                stat->freq_table[i]);
  99        }
 100        if (len >= PAGE_SIZE)
 101                return PAGE_SIZE;
 102
 103        len += snprintf(buf + len, PAGE_SIZE - len, "\n");
 104
 105        for (i = 0; i < stat->state_num; i++) {
 106                if (len >= PAGE_SIZE)
 107                        break;
 108
 109                len += snprintf(buf + len, PAGE_SIZE - len, "%9u: ",
 110                                stat->freq_table[i]);
 111
 112                for (j = 0; j < stat->state_num; j++) {
 113                        if (len >= PAGE_SIZE)
 114                                break;
 115                        len += snprintf(buf + len, PAGE_SIZE - len, "%9u ",
 116                                        stat->trans_table[i*stat->max_state+j]);
 117                }
 118                if (len >= PAGE_SIZE)
 119                        break;
 120                len += snprintf(buf + len, PAGE_SIZE - len, "\n");
 121        }
 122        if (len >= PAGE_SIZE)
 123                return PAGE_SIZE;
 124        return len;
 125}
 126cpufreq_freq_attr_ro(trans_table);
 127#endif
 128
 129cpufreq_freq_attr_ro(total_trans);
 130cpufreq_freq_attr_ro(time_in_state);
 131
 132static struct attribute *default_attrs[] = {
 133        &total_trans.attr,
 134        &time_in_state.attr,
 135#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
 136        &trans_table.attr,
 137#endif
 138        NULL
 139};
 140static struct attribute_group stats_attr_group = {
 141        .attrs = default_attrs,
 142        .name = "stats"
 143};
 144
 145static int freq_table_get_index(struct cpufreq_stats *stat, unsigned int freq)
 146{
 147        int index;
 148        for (index = 0; index < stat->max_state; index++)
 149                if (stat->freq_table[index] == freq)
 150                        return index;
 151        return -1;
 152}
 153
 154/* should be called late in the CPU removal sequence so that the stats
 155 * memory is still available in case someone tries to use it.
 156 */
 157static void cpufreq_stats_free_table(unsigned int cpu)
 158{
 159        struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, cpu);
 160
 161        if (stat) {
 162                pr_debug("%s: Free stat table\n", __func__);
 163                kfree(stat->time_in_state);
 164                kfree(stat);
 165                per_cpu(cpufreq_stats_table, cpu) = NULL;
 166        }
 167}
 168
 169/* must be called early in the CPU removal sequence (before
 170 * cpufreq_remove_dev) so that policy is still valid.
 171 */
 172static void cpufreq_stats_free_sysfs(unsigned int cpu)
 173{
 174        struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
 175
 176        if (!policy)
 177                return;
 178
 179        if (!cpufreq_frequency_get_table(cpu))
 180                goto put_ref;
 181
 182        if (!policy_is_shared(policy)) {
 183                pr_debug("%s: Free sysfs stat\n", __func__);
 184                sysfs_remove_group(&policy->kobj, &stats_attr_group);
 185        }
 186
 187put_ref:
 188        cpufreq_cpu_put(policy);
 189}
 190
 191static int cpufreq_stats_create_table(struct cpufreq_policy *policy,
 192                struct cpufreq_frequency_table *table)
 193{
 194        unsigned int i, j, count = 0, ret = 0;
 195        struct cpufreq_stats *stat;
 196        struct cpufreq_policy *current_policy;
 197        unsigned int alloc_size;
 198        unsigned int cpu = policy->cpu;
 199        if (per_cpu(cpufreq_stats_table, cpu))
 200                return -EBUSY;
 201        stat = kzalloc(sizeof(*stat), GFP_KERNEL);
 202        if ((stat) == NULL)
 203                return -ENOMEM;
 204
 205        current_policy = cpufreq_cpu_get(cpu);
 206        if (current_policy == NULL) {
 207                ret = -EINVAL;
 208                goto error_get_fail;
 209        }
 210
 211        ret = sysfs_create_group(&current_policy->kobj, &stats_attr_group);
 212        if (ret)
 213                goto error_out;
 214
 215        stat->cpu = cpu;
 216        per_cpu(cpufreq_stats_table, cpu) = stat;
 217
 218        for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
 219                unsigned int freq = table[i].frequency;
 220                if (freq == CPUFREQ_ENTRY_INVALID)
 221                        continue;
 222                count++;
 223        }
 224
 225        alloc_size = count * sizeof(int) + count * sizeof(u64);
 226
 227#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
 228        alloc_size += count * count * sizeof(int);
 229#endif
 230        stat->max_state = count;
 231        stat->time_in_state = kzalloc(alloc_size, GFP_KERNEL);
 232        if (!stat->time_in_state) {
 233                ret = -ENOMEM;
 234                goto error_out;
 235        }
 236        stat->freq_table = (unsigned int *)(stat->time_in_state + count);
 237
 238#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
 239        stat->trans_table = stat->freq_table + count;
 240#endif
 241        j = 0;
 242        for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
 243                unsigned int freq = table[i].frequency;
 244                if (freq == CPUFREQ_ENTRY_INVALID)
 245                        continue;
 246                if (freq_table_get_index(stat, freq) == -1)
 247                        stat->freq_table[j++] = freq;
 248        }
 249        stat->state_num = j;
 250        spin_lock(&cpufreq_stats_lock);
 251        stat->last_time = get_jiffies_64();
 252        stat->last_index = freq_table_get_index(stat, policy->cur);
 253        spin_unlock(&cpufreq_stats_lock);
 254        cpufreq_cpu_put(current_policy);
 255        return 0;
 256error_out:
 257        cpufreq_cpu_put(current_policy);
 258error_get_fail:
 259        kfree(stat);
 260        per_cpu(cpufreq_stats_table, cpu) = NULL;
 261        return ret;
 262}
 263
 264static void cpufreq_stats_update_policy_cpu(struct cpufreq_policy *policy)
 265{
 266        struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table,
 267                        policy->last_cpu);
 268
 269        pr_debug("Updating stats_table for new_cpu %u from last_cpu %u\n",
 270                        policy->cpu, policy->last_cpu);
 271        per_cpu(cpufreq_stats_table, policy->cpu) = per_cpu(cpufreq_stats_table,
 272                        policy->last_cpu);
 273        per_cpu(cpufreq_stats_table, policy->last_cpu) = NULL;
 274        stat->cpu = policy->cpu;
 275}
 276
 277static int cpufreq_stat_notifier_policy(struct notifier_block *nb,
 278                unsigned long val, void *data)
 279{
 280        int ret;
 281        struct cpufreq_policy *policy = data;
 282        struct cpufreq_frequency_table *table;
 283        unsigned int cpu = policy->cpu;
 284
 285        if (val == CPUFREQ_UPDATE_POLICY_CPU) {
 286                cpufreq_stats_update_policy_cpu(policy);
 287                return 0;
 288        }
 289
 290        if (val != CPUFREQ_NOTIFY)
 291                return 0;
 292        table = cpufreq_frequency_get_table(cpu);
 293        if (!table)
 294                return 0;
 295        ret = cpufreq_stats_create_table(policy, table);
 296        if (ret)
 297                return ret;
 298        return 0;
 299}
 300
 301static int cpufreq_stat_notifier_trans(struct notifier_block *nb,
 302                unsigned long val, void *data)
 303{
 304        struct cpufreq_freqs *freq = data;
 305        struct cpufreq_stats *stat;
 306        int old_index, new_index;
 307
 308        if (val != CPUFREQ_POSTCHANGE)
 309                return 0;
 310
 311        stat = per_cpu(cpufreq_stats_table, freq->cpu);
 312        if (!stat)
 313                return 0;
 314
 315        old_index = stat->last_index;
 316        new_index = freq_table_get_index(stat, freq->new);
 317
 318        /* We can't do stat->time_in_state[-1]= .. */
 319        if (old_index == -1 || new_index == -1)
 320                return 0;
 321
 322        cpufreq_stats_update(freq->cpu);
 323
 324        if (old_index == new_index)
 325                return 0;
 326
 327        spin_lock(&cpufreq_stats_lock);
 328        stat->last_index = new_index;
 329#ifdef CONFIG_CPU_FREQ_STAT_DETAILS
 330        stat->trans_table[old_index * stat->max_state + new_index]++;
 331#endif
 332        stat->total_trans++;
 333        spin_unlock(&cpufreq_stats_lock);
 334        return 0;
 335}
 336
 337static int cpufreq_stat_cpu_callback(struct notifier_block *nfb,
 338                                               unsigned long action,
 339                                               void *hcpu)
 340{
 341        unsigned int cpu = (unsigned long)hcpu;
 342
 343        switch (action) {
 344        case CPU_DOWN_PREPARE:
 345                cpufreq_stats_free_sysfs(cpu);
 346                break;
 347        case CPU_DEAD:
 348                cpufreq_stats_free_table(cpu);
 349                break;
 350        }
 351        return NOTIFY_OK;
 352}
 353
 354/* priority=1 so this will get called before cpufreq_remove_dev */
 355static struct notifier_block cpufreq_stat_cpu_notifier __refdata = {
 356        .notifier_call = cpufreq_stat_cpu_callback,
 357        .priority = 1,
 358};
 359
 360static struct notifier_block notifier_policy_block = {
 361        .notifier_call = cpufreq_stat_notifier_policy
 362};
 363
 364static struct notifier_block notifier_trans_block = {
 365        .notifier_call = cpufreq_stat_notifier_trans
 366};
 367
 368static int __init cpufreq_stats_init(void)
 369{
 370        int ret;
 371        unsigned int cpu;
 372
 373        spin_lock_init(&cpufreq_stats_lock);
 374        ret = cpufreq_register_notifier(&notifier_policy_block,
 375                                CPUFREQ_POLICY_NOTIFIER);
 376        if (ret)
 377                return ret;
 378
 379        register_hotcpu_notifier(&cpufreq_stat_cpu_notifier);
 380
 381        ret = cpufreq_register_notifier(&notifier_trans_block,
 382                                CPUFREQ_TRANSITION_NOTIFIER);
 383        if (ret) {
 384                cpufreq_unregister_notifier(&notifier_policy_block,
 385                                CPUFREQ_POLICY_NOTIFIER);
 386                unregister_hotcpu_notifier(&cpufreq_stat_cpu_notifier);
 387                for_each_online_cpu(cpu)
 388                        cpufreq_stats_free_table(cpu);
 389                return ret;
 390        }
 391
 392        return 0;
 393}
 394static void __exit cpufreq_stats_exit(void)
 395{
 396        unsigned int cpu;
 397
 398        cpufreq_unregister_notifier(&notifier_policy_block,
 399                        CPUFREQ_POLICY_NOTIFIER);
 400        cpufreq_unregister_notifier(&notifier_trans_block,
 401                        CPUFREQ_TRANSITION_NOTIFIER);
 402        unregister_hotcpu_notifier(&cpufreq_stat_cpu_notifier);
 403        for_each_online_cpu(cpu) {
 404                cpufreq_stats_free_table(cpu);
 405                cpufreq_stats_free_sysfs(cpu);
 406        }
 407}
 408
 409MODULE_AUTHOR("Zou Nan hai <nanhai.zou@intel.com>");
 410MODULE_DESCRIPTION("'cpufreq_stats' - A driver to export cpufreq stats "
 411                                "through sysfs filesystem");
 412MODULE_LICENSE("GPL");
 413
 414module_init(cpufreq_stats_init);
 415module_exit(cpufreq_stats_exit);
 416
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