linux/drivers/cpufreq/vexpress-spc-cpufreq.c
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   1/*
   2 * Versatile Express SPC CPUFreq Interface driver
   3 *
   4 * It provides necessary ops to arm_big_little cpufreq driver.
   5 *
   6 * Copyright (C) 2013 ARM Ltd.
   7 * Sudeep KarkadaNagesha <sudeep.karkadanagesha@arm.com>
   8 *
   9 * This program is free software; you can redistribute it and/or modify
  10 * it under the terms of the GNU General Public License version 2 as
  11 * published by the Free Software Foundation.
  12 *
  13 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
  14 * kind, whether express or implied; without even the implied warranty
  15 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16 * GNU General Public License for more details.
  17 */
  18
  19#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  20
  21#include <linux/cpu.h>
  22#include <linux/cpufreq.h>
  23#include <linux/module.h>
  24#include <linux/platform_device.h>
  25#include <linux/pm_opp.h>
  26#include <linux/types.h>
  27
  28#include "arm_big_little.h"
  29
  30static int ve_spc_init_opp_table(const struct cpumask *cpumask)
  31{
  32        struct device *cpu_dev = get_cpu_device(cpumask_first(cpumask));
  33        /*
  34         * platform specific SPC code must initialise the opp table
  35         * so just check if the OPP count is non-zero
  36         */
  37        return dev_pm_opp_get_opp_count(cpu_dev) <= 0;
  38}
  39
  40static int ve_spc_get_transition_latency(struct device *cpu_dev)
  41{
  42        return 1000000; /* 1 ms */
  43}
  44
  45static struct cpufreq_arm_bL_ops ve_spc_cpufreq_ops = {
  46        .name   = "vexpress-spc",
  47        .get_transition_latency = ve_spc_get_transition_latency,
  48        .init_opp_table = ve_spc_init_opp_table,
  49};
  50
  51static int ve_spc_cpufreq_probe(struct platform_device *pdev)
  52{
  53        return bL_cpufreq_register(&ve_spc_cpufreq_ops);
  54}
  55
  56static int ve_spc_cpufreq_remove(struct platform_device *pdev)
  57{
  58        bL_cpufreq_unregister(&ve_spc_cpufreq_ops);
  59        return 0;
  60}
  61
  62static struct platform_driver ve_spc_cpufreq_platdrv = {
  63        .driver = {
  64                .name   = "vexpress-spc-cpufreq",
  65        },
  66        .probe          = ve_spc_cpufreq_probe,
  67        .remove         = ve_spc_cpufreq_remove,
  68};
  69module_platform_driver(ve_spc_cpufreq_platdrv);
  70
  71MODULE_LICENSE("GPL");
  72
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