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 struct scpi_dvfs_info *scpi_get_dvfs_info(struct device *cpu_dev)
  34 {
  35         int domain = topology_physical_package_id(cpu_dev->id);
  36
  37         if (domain < 0)
  38                 return ERR_PTR(-EINVAL);
  39         return scpi_ops->dvfs_get_info(domain);
  40 }
  41
  42 static int scpi_get_transition_latency(struct device *cpu_dev)
  43 {
  44         struct scpi_dvfs_info *info = scpi_get_dvfs_info(cpu_dev);
  45
  46         if (IS_ERR(info))
  47                 return PTR_ERR(info);
  48         return info->latency;
  49 }
  50
  51 static int scpi_init_opp_table(const struct cpumask *cpumask)
  52 {
  53         int idx, ret;
  54         struct scpi_opp *opp;
  55         struct device *cpu_dev = get_cpu_device(cpumask_first(cpumask));
  56         struct scpi_dvfs_info *info = scpi_get_dvfs_info(cpu_dev);
  57
  58         if (IS_ERR(info))
  59                 return PTR_ERR(info);
  60
  61         if (!info->opps)
  62                 return -EIO;
  63
  64         for (opp = info->opps, idx = 0; idx < info->count; idx++, opp++) {
  65                 ret = dev_pm_opp_add(cpu_dev, opp->freq, opp->m_volt * 1000);
  66                 if (ret) {
  67                         dev_warn(cpu_dev, "failed to add opp %uHz %umV\n",
  68                                  opp->freq, opp->m_volt);
  69                         while (idx-- > 0)
  70                                 dev_pm_opp_remove(cpu_dev, (--opp)->freq);
  71                         return ret;
  72                 }
  73         }
  74
  75         ret = dev_pm_opp_set_sharing_cpus(cpu_dev, cpumask);
  76         if (ret)
  77                 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
  78                         __func__, ret);
  79         return ret;
  80 }
  81
  82 static struct cpufreq_arm_bL_ops scpi_cpufreq_ops = {
  83         .name   = "scpi",
  84         .get_transition_latency = scpi_get_transition_latency,
  85         .init_opp_table = scpi_init_opp_table,
  86         .free_opp_table = dev_pm_opp_cpumask_remove_table,
  87 };
  88
  89 static int scpi_cpufreq_probe(struct platform_device *pdev)
  90 {
  91         scpi_ops = get_scpi_ops();
  92         if (!scpi_ops)
  93                 return -EIO;
  94
  95         return bL_cpufreq_register(&scpi_cpufreq_ops);
  96 }
  97
  98 static int scpi_cpufreq_remove(struct platform_device *pdev)
  99 {
 100         bL_cpufreq_unregister(&scpi_cpufreq_ops);
 101         scpi_ops = NULL;
 102         return 0;
 103 }
 104
 105 static struct platform_driver scpi_cpufreq_platdrv = {
 106         .driver = {
 107                 .name   = "scpi-cpufreq",
 108                 .owner  = THIS_MODULE,
 109         },
 110         .probe          = scpi_cpufreq_probe,
 111         .remove         = scpi_cpufreq_remove,
 112 };
 113 module_platform_driver(scpi_cpufreq_platdrv);
 114
 115 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
 116 MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver");
 117 MODULE_LICENSE("GPL v2");