drivers/cpufreq/vexpress-spc-cpufreq.c

   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
  30 static 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
  40 static int ve_spc_get_transition_latency(struct device *cpu_dev)
  41 {
  42         return 1000000; /* 1 ms */
  43 }
  44
  45 static const 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
  51 static int ve_spc_cpufreq_probe(struct platform_device *pdev)
  52 {
  53         return bL_cpufreq_register(&ve_spc_cpufreq_ops);
  54 }
  55
  56 static int ve_spc_cpufreq_remove(struct platform_device *pdev)
  57 {
  58         bL_cpufreq_unregister(&ve_spc_cpufreq_ops);
  59         return 0;
  60 }
  61
  62 static 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 };
  69 module_platform_driver(ve_spc_cpufreq_platdrv);
  70
  71 MODULE_LICENSE("GPL");