drivers/cpuquiet/driver.c

   1 /*
   2  * Copyright (c) 2012 NVIDIA CORPORATION.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; version 2 of the License.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  16  *
  17  */
  18
  19 #include <linux/mutex.h>
  20 #include <linux/module.h>
  21 #include <linux/cpuquiet.h>
  22 #include <linux/cpu.h>
  23 #include <linux/jiffies.h>
  24 #include <linux/slab.h>
  25 #include <asm/cputime.h>
  26
  27 #include "cpuquiet.h"
  28
  29 struct cpuquiet_cpu_stat {
  30         cputime64_t time_up_total;
  31         u64 last_update;
  32         unsigned int up_down_count;
  33         struct kobject cpu_kobject;
  34 };
  35
  36 struct cpu_attribute {
  37         struct attribute attr;
  38         enum { up_down_count, time_up_total } type;
  39 };
  40
  41 static struct cpuquiet_driver *cpuquiet_curr_driver;
  42 struct cpuquiet_cpu_stat *stats;
  43
  44 #define CPU_ATTRIBUTE(_name) \
  45         static struct cpu_attribute _name ## _attr = {                  \
  46                 .attr =  {.name = __stringify(_name), .mode = 0444 },   \
  47                 .type   = _name,                                        \
  48 }
  49
  50 CPU_ATTRIBUTE(up_down_count);
  51 CPU_ATTRIBUTE(time_up_total);
  52
  53 static struct attribute *cpu_attributes[] = {
  54         &up_down_count_attr.attr,
  55         &time_up_total_attr.attr,
  56         NULL,
  57 };
  58
  59 static void stats_update(struct cpuquiet_cpu_stat *stat, bool up)
  60 {
  61         u64 cur_jiffies = get_jiffies_64();
  62         bool was_up = stat->up_down_count & 0x1;
  63
  64         if (was_up)
  65                 stat->time_up_total += cur_jiffies - stat->last_update;
  66
  67         if (was_up != up)
  68                 stat->up_down_count++;
  69
  70         stat->last_update = cur_jiffies;
  71 }
  72
  73 int cpuquiet_quiesence_cpu(unsigned int cpunumber)
  74 {
  75         int err = -EPERM;
  76
  77         if (cpuquiet_curr_driver && cpuquiet_curr_driver->quiesence_cpu)
  78                 err = cpuquiet_curr_driver->quiesence_cpu(cpunumber);
  79
  80         if (!err)
  81                 stats_update(stats + cpunumber, 0);
  82
  83         return err;
  84 }
  85 EXPORT_SYMBOL(cpuquiet_quiesence_cpu);
  86
  87 int cpuquiet_wake_cpu(unsigned int cpunumber)
  88 {
  89         int err = -EPERM;
  90
  91         if (cpuquiet_curr_driver && cpuquiet_curr_driver->wake_cpu)
  92                 err = cpuquiet_curr_driver->wake_cpu(cpunumber);
  93
  94         if (!err)
  95                 stats_update(stats + cpunumber, 1);
  96
  97         return err;
  98 }
  99 EXPORT_SYMBOL(cpuquiet_wake_cpu);
 100
 101 static ssize_t stats_sysfs_show(struct kobject *kobj,
 102                         struct attribute *attr, char *buf)
 103 {
 104         struct cpu_attribute *cattr =
 105                 container_of(attr, struct cpu_attribute, attr);
 106         struct cpuquiet_cpu_stat *stat  =
 107                 container_of(kobj, struct cpuquiet_cpu_stat, cpu_kobject);
 108         ssize_t len = 0;
 109         bool was_up = stat->up_down_count & 0x1;
 110
 111         stats_update(stat, was_up);
 112
 113         switch (cattr->type) {
 114         case up_down_count:
 115                 len = sprintf(buf, "%u\n", stat->up_down_count);
 116                 break;
 117         case time_up_total:
 118                 len =  sprintf(buf, "%llu\n", stat->time_up_total);
 119                 break;
 120         }
 121
 122         return len;
 123 }
 124
 125 static const struct sysfs_ops stats_sysfs_ops = {
 126         .show = stats_sysfs_show,
 127 };
 128
 129 static struct kobj_type ktype_cpu_stats = {
 130         .sysfs_ops = &stats_sysfs_ops,
 131         .default_attrs = cpu_attributes,
 132 };
 133
 134 int cpuquiet_register_driver(struct cpuquiet_driver *drv)
 135 {
 136         int err = -EBUSY;
 137         unsigned int cpu;
 138         struct device *dev;
 139         u64 cur_jiffies;
 140
 141         if (!drv)
 142                 return -EINVAL;
 143
 144         stats = kzalloc(nr_cpu_ids * sizeof(*stats), GFP_KERNEL);
 145         if (!stats)
 146                 return -ENOMEM;
 147
 148         for_each_possible_cpu(cpu) {
 149                 cur_jiffies = get_jiffies_64();
 150                 stats[cpu].last_update = cur_jiffies;
 151                 if (cpu_online(cpu))
 152                         stats[cpu].up_down_count = 1;
 153                 dev = get_cpu_device(cpu);
 154                 if (dev) {
 155                         cpuquiet_add_dev(dev, cpu);
 156                         cpuquiet_cpu_kobject_init(&stats[cpu].cpu_kobject,
 157                                         &ktype_cpu_stats, "stats", cpu);
 158                 }
 159         }
 160
 161         mutex_lock(&cpuquiet_lock);
 162         if (!cpuquiet_curr_driver) {
 163                 err = 0;
 164                 cpuquiet_curr_driver = drv;
 165                 cpuquiet_switch_governor(cpuquiet_get_first_governor());
 166         }
 167         mutex_unlock(&cpuquiet_lock);
 168
 169         return err;
 170 }
 171 EXPORT_SYMBOL(cpuquiet_register_driver);
 172
 173 struct cpuquiet_driver *cpuquiet_get_driver(void)
 174 {
 175         return cpuquiet_curr_driver;
 176 }
 177
 178 void cpuquiet_unregister_driver(struct cpuquiet_driver *drv)
 179 {
 180         unsigned int cpu;
 181
 182         if (drv != cpuquiet_curr_driver) {
 183                 WARN(1, "invalid cpuquiet_unregister_driver(%s)\n",
 184                         drv->name);
 185                 return;
 186         }
 187
 188         /* stop current governor first */
 189         cpuquiet_switch_governor(NULL);
 190
 191         mutex_lock(&cpuquiet_lock);
 192         cpuquiet_curr_driver = NULL;
 193
 194         for_each_possible_cpu(cpu) {
 195                 kobject_put(&stats[cpu].cpu_kobject);
 196                 cpuquiet_remove_dev(cpu);
 197         }
 198
 199         mutex_unlock(&cpuquiet_lock);
 200 }
 201 EXPORT_SYMBOL(cpuquiet_unregister_driver);