linux/drivers/cpufreq/arm_big_little_dt.c
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   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 */
  34static 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
  46static 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
  63static 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
  81static 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
  87static 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
  99static int generic_bL_remove(struct platform_device *pdev)
 100{
 101        bL_cpufreq_unregister(&dt_bL_ops);
 102        return 0;
 103}
 104
 105static 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};
 113module_platform_driver(generic_bL_platdrv);
 114
 115MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
 116MODULE_DESCRIPTION("Generic ARM big LITTLE cpufreq driver via DT");
 117MODULE_LICENSE("GPL");
 118
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