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/cpufreq.h>
  22#include <linux/module.h>
  23#include <linux/platform_device.h>
  24#include <linux/pm_opp.h>
  25#include <linux/types.h>
  26
  27#include "arm_big_little.h"
  28
  29static int ve_spc_init_opp_table(struct device *cpu_dev)
  30{
  31        /*
  32         * platform specific SPC code must initialise the opp table
  33         * so just check if the OPP count is non-zero
  34         */
  35        return dev_pm_opp_get_opp_count(cpu_dev) <= 0;
  36}
  37
  38static int ve_spc_get_transition_latency(struct device *cpu_dev)
  39{
  40        return 1000000; /* 1 ms */
  41}
  42
  43static struct cpufreq_arm_bL_ops ve_spc_cpufreq_ops = {
  44        .name   = "vexpress-spc",
  45        .get_transition_latency = ve_spc_get_transition_latency,
  46        .init_opp_table = ve_spc_init_opp_table,
  47};
  48
  49static int ve_spc_cpufreq_probe(struct platform_device *pdev)
  50{
  51        return bL_cpufreq_register(&ve_spc_cpufreq_ops);
  52}
  53
  54static int ve_spc_cpufreq_remove(struct platform_device *pdev)
  55{
  56        bL_cpufreq_unregister(&ve_spc_cpufreq_ops);
  57        return 0;
  58}
  59
  60static struct platform_driver ve_spc_cpufreq_platdrv = {
  61        .driver = {
  62                .name   = "vexpress-spc-cpufreq",
  63                .owner  = THIS_MODULE,
  64        },
  65        .probe          = ve_spc_cpufreq_probe,
  66        .remove         = ve_spc_cpufreq_remove,
  67};
  68module_platform_driver(ve_spc_cpufreq_platdrv);
  69
  70MODULE_LICENSE("GPL");
  71
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