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/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_init_opp_table(struct device *cpu_dev)
  47 {
  48         struct device_node *np;
  49         int ret;
  50
  51         np = of_node_get(cpu_dev->of_node);
  52         if (!np) {
  53                 pr_err("failed to find cpu%d node\n", cpu_dev->id);
  54                 return -ENOENT;
  55         }
  56
  57         ret = of_init_opp_table(cpu_dev);
  58         of_node_put(np);
  59
  60         return ret;
  61 }
  62
  63 static int dt_get_transition_latency(struct device *cpu_dev)
  64 {
  65         struct device_node *np;
  66         u32 transition_latency = CPUFREQ_ETERNAL;
  67
  68         np = of_node_get(cpu_dev->of_node);
  69         if (!np) {
  70                 pr_info("Failed to find cpu node. Use CPUFREQ_ETERNAL transition latency\n");
  71                 return CPUFREQ_ETERNAL;
  72         }
  73
  74         of_property_read_u32(np, "clock-latency", &transition_latency);
  75         of_node_put(np);
  76
  77         pr_debug("%s: clock-latency: %d\n", __func__, transition_latency);
  78         return transition_latency;
  79 }
  80
  81 static struct cpufreq_arm_bL_ops dt_bL_ops = {
  82         .name   = "dt-bl",
  83         .get_transition_latency = dt_get_transition_latency,
  84         .init_opp_table = dt_init_opp_table,
  85 };
  86
  87 static int generic_bL_probe(struct platform_device *pdev)
  88 {
  89         struct device_node *np;
  90
  91         np = get_cpu_node_with_valid_op(0);
  92         if (!np)
  93                 return -ENODEV;
  94
  95         of_node_put(np);
  96         return bL_cpufreq_register(&dt_bL_ops);
  97 }
  98
  99 static int generic_bL_remove(struct platform_device *pdev)
 100 {
 101         bL_cpufreq_unregister(&dt_bL_ops);
 102         return 0;
 103 }
 104
 105 static struct platform_driver generic_bL_platdrv = {
 106         .driver = {
 107                 .name   = "arm-bL-cpufreq-dt",
 108                 .owner  = THIS_MODULE,
 109         },
 110         .probe          = generic_bL_probe,
 111         .remove         = generic_bL_remove,
 112 };
 113 module_platform_driver(generic_bL_platdrv);
 114
 115 MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
 116 MODULE_DESCRIPTION("Generic ARM big LITTLE cpufreq driver via DT");
 117 MODULE_LICENSE("GPL");