kernel/sched/energy.c

   1 /*
   2  * Obtain energy cost data from DT and populate relevant scheduler data
   3  * structures.
   4  *
   5  * Copyright (C) 2015 ARM Ltd.
   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  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19 #define pr_fmt(fmt) "sched-energy: " fmt
  20
  21 #define DEBUG
  22
  23 #include <linux/gfp.h>
  24 #include <linux/of.h>
  25 #include <linux/printk.h>
  26 #include <linux/sched.h>
  27 #include <linux/sched_energy.h>
  28 #include <linux/stddef.h>
  29
  30 struct sched_group_energy *sge_array[NR_CPUS][NR_SD_LEVELS];
  31
  32 static void free_resources(void)
  33 {
  34         int cpu, sd_level;
  35         struct sched_group_energy *sge;
  36
  37         for_each_possible_cpu(cpu) {
  38                 for_each_possible_sd_level(sd_level) {
  39                         sge = sge_array[cpu][sd_level];
  40                         if (sge) {
  41                                 kfree(sge->cap_states);
  42                                 kfree(sge->idle_states);
  43                                 kfree(sge);
  44                         }
  45                 }
  46         }
  47 }
  48
  49 void init_sched_energy_costs(void)
  50 {
  51         struct device_node *cn, *cp;
  52         struct capacity_state *cap_states;
  53         struct idle_state *idle_states;
  54         struct sched_group_energy *sge;
  55         const struct property *prop;
  56         int sd_level, i, nstates, cpu;
  57         const __be32 *val;
  58
  59         for_each_possible_cpu(cpu) {
  60                 cn = of_get_cpu_node(cpu, NULL);
  61                 if (!cn) {
  62                         pr_warn("CPU device node missing for CPU %d\n", cpu);
  63                         return;
  64                 }
  65
  66                 if (!of_find_property(cn, "sched-energy-costs", NULL)) {
  67                         pr_warn("CPU device node has no sched-energy-costs\n");
  68                         return;
  69                 }
  70
  71                 for_each_possible_sd_level(sd_level) {
  72                         cp = of_parse_phandle(cn, "sched-energy-costs", sd_level);
  73                         if (!cp)
  74                                 break;
  75
  76                         prop = of_find_property(cp, "busy-cost-data", NULL);
  77                         if (!prop || !prop->value) {
  78                                 pr_warn("No busy-cost data, skipping sched_energy init\n");
  79                                 goto out;
  80                         }
  81
  82                         sge = kcalloc(1, sizeof(struct sched_group_energy),
  83                                       GFP_NOWAIT);
  84
  85                         nstates = (prop->length / sizeof(u32)) / 2;
  86                         cap_states = kcalloc(nstates,
  87                                              sizeof(struct capacity_state),
  88                                              GFP_NOWAIT);
  89
  90                         for (i = 0, val = prop->value; i < nstates; i++) {
  91                                 cap_states[i].cap = be32_to_cpup(val++);
  92                                 cap_states[i].power = be32_to_cpup(val++);
  93                         }
  94
  95                         sge->nr_cap_states = nstates;
  96                         sge->cap_states = cap_states;
  97
  98                         prop = of_find_property(cp, "idle-cost-data", NULL);
  99                         if (!prop || !prop->value) {
 100                                 pr_warn("No idle-cost data, skipping sched_energy init\n");
 101                                 goto out;
 102                         }
 103
 104                         nstates = (prop->length / sizeof(u32));
 105                         idle_states = kcalloc(nstates,
 106                                               sizeof(struct idle_state),
 107                                               GFP_NOWAIT);
 108
 109                         for (i = 0, val = prop->value; i < nstates; i++)
 110                                 idle_states[i].power = be32_to_cpup(val++);
 111
 112                         sge->nr_idle_states = nstates;
 113                         sge->idle_states = idle_states;
 114
 115                         sge_array[cpu][sd_level] = sge;
 116                 }
 117         }
 118
 119         pr_info("Sched-energy-costs installed from DT\n");
 120         return;
 121
 122 out:
 123         free_resources();
 124 }