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/cpufreq.h>
  22 #include <linux/module.h>
  23 #include <linux/platform_device.h>
  24 #include <linux/pm_opp.h>
  25 #include <linux/scpi_protocol.h>
  26 #include <linux/types.h>
  27
  28 #include "arm_big_little.h"
  29
  30 static struct scpi_ops *scpi_ops;
  31
  32 static struct scpi_dvfs_info *scpi_get_dvfs_info(struct device *cpu_dev)
  33 {
  34         u8 domain = topology_physical_package_id(cpu_dev->id);
  35
  36         if (domain < 0)
  37                 return ERR_PTR(-EINVAL);
  38         return scpi_ops->dvfs_get_info(domain);
  39 }
  40
  41 static int scpi_opp_table_ops(struct device *cpu_dev, bool remove)
  42 {
  43         int idx, ret = 0;
  44         struct scpi_opp *opp;
  45         struct scpi_dvfs_info *info = scpi_get_dvfs_info(cpu_dev);
  46
  47         if (IS_ERR(info))
  48                 return PTR_ERR(info);
  49
  50         if (!info->opps)
  51                 return -EIO;
  52
  53         for (opp = info->opps, idx = 0; idx < info->count; idx++, opp++) {
  54                 if (remove)
  55                         dev_pm_opp_remove(cpu_dev, opp->freq);
  56                 else
  57                         ret = dev_pm_opp_add(cpu_dev, opp->freq,
  58                                              opp->m_volt * 1000);
  59                 if (ret) {
  60                         dev_warn(cpu_dev, "failed to add opp %uHz %umV\n",
  61                                  opp->freq, opp->m_volt);
  62                         while (idx-- > 0)
  63                                 dev_pm_opp_remove(cpu_dev, (--opp)->freq);
  64                         return ret;
  65                 }
  66         }
  67         return ret;
  68 }
  69
  70 static int scpi_get_transition_latency(struct device *cpu_dev)
  71 {
  72         struct scpi_dvfs_info *info = scpi_get_dvfs_info(cpu_dev);
  73
  74         if (IS_ERR(info))
  75                 return PTR_ERR(info);
  76         return info->latency;
  77 }
  78
  79 static int scpi_init_opp_table(struct device *cpu_dev)
  80 {
  81         return scpi_opp_table_ops(cpu_dev, false);
  82 }
  83
  84 static void scpi_free_opp_table(struct device *cpu_dev)
  85 {
  86         scpi_opp_table_ops(cpu_dev, true);
  87 }
  88
  89 static struct cpufreq_arm_bL_ops scpi_cpufreq_ops = {
  90         .name   = "scpi",
  91         .get_transition_latency = scpi_get_transition_latency,
  92         .init_opp_table = scpi_init_opp_table,
  93         .free_opp_table = scpi_free_opp_table,
  94 };
  95
  96 static int scpi_cpufreq_probe(struct platform_device *pdev)
  97 {
  98         scpi_ops = get_scpi_ops();
  99         if (!scpi_ops)
 100                 return -EIO;
 101
 102         return bL_cpufreq_register(&scpi_cpufreq_ops);
 103 }
 104
 105 static int scpi_cpufreq_remove(struct platform_device *pdev)
 106 {
 107         bL_cpufreq_unregister(&scpi_cpufreq_ops);
 108         scpi_ops = NULL;
 109         return 0;
 110 }
 111
 112 static struct platform_driver scpi_cpufreq_platdrv = {
 113         .driver = {
 114                 .name   = "scpi-cpufreq",
 115                 .owner  = THIS_MODULE,
 116         },
 117         .probe          = scpi_cpufreq_probe,
 118         .remove         = scpi_cpufreq_remove,
 119 };
 120 module_platform_driver(scpi_cpufreq_platdrv);
 121
 122 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
 123 MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver");
 124 MODULE_LICENSE("GPL v2");