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_device.h>
  27 #include <linux/pm_opp.h>
  28 #include <linux/platform_device.h>
  29 #include <linux/slab.h>
  30 #include <linux/types.h>
  31 #include "arm_big_little.h"
  32
  33 /* get cpu node with valid operating-points */
  34 static struct device_node *get_cpu_node_with_valid_op(int cpu)
  35 {
  36         struct device_node *np = of_cpu_device_node_get(cpu);
  37
  38         if (!of_get_property(np, "operating-points", NULL)) {
  39                 of_node_put(np);
  40                 np = NULL;
  41         }
  42
  43         return np;
  44 }
  45
  46 static int dt_get_transition_latency(struct device *cpu_dev)
  47 {
  48         struct device_node *np;
  49         u32 transition_latency = CPUFREQ_ETERNAL;
  50
  51         np = of_node_get(cpu_dev->of_node);
  52         if (!np) {
  53                 pr_info("Failed to find cpu node. Use CPUFREQ_ETERNAL transition latency\n");
  54                 return CPUFREQ_ETERNAL;
  55         }
  56
  57         of_property_read_u32(np, "clock-latency", &transition_latency);
  58         of_node_put(np);
  59
  60         pr_debug("%s: clock-latency: %d\n", __func__, transition_latency);
  61         return transition_latency;
  62 }
  63
  64 static const struct cpufreq_arm_bL_ops dt_bL_ops = {
  65         .name   = "dt-bl",
  66         .get_transition_latency = dt_get_transition_latency,
  67         .init_opp_table = dev_pm_opp_of_cpumask_add_table,
  68         .free_opp_table = dev_pm_opp_of_cpumask_remove_table,
  69 };
  70
  71 static int generic_bL_probe(struct platform_device *pdev)
  72 {
  73         struct device_node *np;
  74
  75         np = get_cpu_node_with_valid_op(0);
  76         if (!np)
  77                 return -ENODEV;
  78
  79         of_node_put(np);
  80         return bL_cpufreq_register(&dt_bL_ops);
  81 }
  82
  83 static int generic_bL_remove(struct platform_device *pdev)
  84 {
  85         bL_cpufreq_unregister(&dt_bL_ops);
  86         return 0;
  87 }
  88
  89 static struct platform_driver generic_bL_platdrv = {
  90         .driver = {
  91                 .name   = "arm-bL-cpufreq-dt",
  92         },
  93         .probe          = generic_bL_probe,
  94         .remove         = generic_bL_remove,
  95 };
  96 module_platform_driver(generic_bL_platdrv);
  97
  98 MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
  99 MODULE_DESCRIPTION("Generic ARM big LITTLE cpufreq driver via DT");
 100 MODULE_LICENSE("GPL v2");