drivers/cpufreq/scpi-cpufreq.c

   1 /*
   2  * System Control and Power Interface (SCPI) based CPUFreq Interface driver
   3  *
   4  * It provides necessary ops to arm_big_little cpufreq driver.
   5  *
   6  * Copyright (C) 2015 ARM Ltd.
   7  * Sudeep Holla <sudeep.holla@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/scpi_protocol.h>
  27 #include <linux/types.h>
  28
  29 #include "arm_big_little.h"
  30
  31 static struct scpi_ops *scpi_ops;
  32
  33 static int scpi_get_transition_latency(struct device *cpu_dev)
  34 {
  35         return scpi_ops->get_transition_latency(cpu_dev);
  36 }
  37
  38 static int scpi_init_opp_table(const struct cpumask *cpumask)
  39 {
  40         int ret;
  41         struct device *cpu_dev = get_cpu_device(cpumask_first(cpumask));
  42
  43         ret = scpi_ops->add_opps_to_device(cpu_dev);
  44         if (ret) {
  45                 dev_warn(cpu_dev, "failed to add opps to the device\n");
  46                 return ret;
  47         }
  48
  49         ret = dev_pm_opp_set_sharing_cpus(cpu_dev, cpumask);
  50         if (ret)
  51                 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
  52                         __func__, ret);
  53         return ret;
  54 }
  55
  56 static struct cpufreq_arm_bL_ops scpi_cpufreq_ops = {
  57         .name   = "scpi",
  58         .get_transition_latency = scpi_get_transition_latency,
  59         .init_opp_table = scpi_init_opp_table,
  60         .free_opp_table = dev_pm_opp_cpumask_remove_table,
  61 };
  62
  63 static int scpi_cpufreq_probe(struct platform_device *pdev)
  64 {
  65         scpi_ops = get_scpi_ops();
  66         if (!scpi_ops)
  67                 return -EIO;
  68
  69         return bL_cpufreq_register(&scpi_cpufreq_ops);
  70 }
  71
  72 static int scpi_cpufreq_remove(struct platform_device *pdev)
  73 {
  74         bL_cpufreq_unregister(&scpi_cpufreq_ops);
  75         scpi_ops = NULL;
  76         return 0;
  77 }
  78
  79 static struct platform_driver scpi_cpufreq_platdrv = {
  80         .driver = {
  81                 .name   = "scpi-cpufreq",
  82         },
  83         .probe          = scpi_cpufreq_probe,
  84         .remove         = scpi_cpufreq_remove,
  85 };
  86 module_platform_driver(scpi_cpufreq_platdrv);
  87
  88 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
  89 MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver");
  90 MODULE_LICENSE("GPL v2");