drivers/cpufreq/arm_big_little_dt.c

   1 /*
   2  * Generic big.LITTLE CPUFreq Interface driver
   3  *
   4  * It provides necessary ops to arm_big_little cpufreq driver and gets
   5  * Frequency information from Device Tree. Freq table in DT must be in KHz.
   6  *
   7  * Copyright (C) 2013 Linaro.
   8  * Viresh Kumar <viresh.kumar@linaro.org>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  *
  14  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
  15  * kind, whether express or implied; without even the implied warranty
  16  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  17  * GNU General Public License for more details.
  18  */
  19
  20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  21
  22 #include <linux/cpufreq.h>
  23 #include <linux/device.h>
  24 #include <linux/export.h>
  25 #include <linux/module.h>
  26 #include <linux/of.h>
  27 #include <linux/opp.h>
  28 #include <linux/slab.h>
  29 #include <linux/types.h>
  30 #include "arm_big_little.h"
  31
  32 static int dt_init_opp_table(struct device *cpu_dev)
  33 {
  34         struct device_node *np = NULL;
  35         int count = 0, ret;
  36
  37         for_each_child_of_node(of_find_node_by_path("/cpus"), np) {
  38                 if (count++ != cpu_dev->id)
  39                         continue;
  40                 if (!of_get_property(np, "operating-points", NULL))
  41                         return -ENODATA;
  42
  43                 cpu_dev->of_node = np;
  44
  45                 ret = of_init_opp_table(cpu_dev);
  46                 if (ret)
  47                         return ret;
  48
  49                 return 0;
  50         }
  51
  52         return -ENODEV;
  53 }
  54
  55 static int dt_get_transition_latency(struct device *cpu_dev)
  56 {
  57         struct device_node *np = NULL;
  58         u32 transition_latency = CPUFREQ_ETERNAL;
  59         int count = 0;
  60
  61         for_each_child_of_node(of_find_node_by_path("/cpus"), np) {
  62                 if (count++ != cpu_dev->id)
  63                         continue;
  64
  65                 of_property_read_u32(np, "clock-latency", &transition_latency);
  66                 return 0;
  67         }
  68
  69         return -ENODEV;
  70 }
  71
  72 static struct cpufreq_arm_bL_ops dt_bL_ops = {
  73         .name   = "dt-bl",
  74         .get_transition_latency = dt_get_transition_latency,
  75         .init_opp_table = dt_init_opp_table,
  76 };
  77
  78 static int generic_bL_init(void)
  79 {
  80         return bL_cpufreq_register(&dt_bL_ops);
  81 }
  82 module_init(generic_bL_init);
  83
  84 static void generic_bL_exit(void)
  85 {
  86         return bL_cpufreq_unregister(&dt_bL_ops);
  87 }
  88 module_exit(generic_bL_exit);
  89
  90 MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
  91 MODULE_DESCRIPTION("Generic ARM big LITTLE cpufreq driver via DT");
  92 MODULE_LICENSE("GPL");