cpufreq_device.cc

// Copyright 2015 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "thermald/cpufreq_device.h"

#include <string>
#include <vector>

#include "base/check.h"
#include "base/files/file_enumerator.h"
#include "base/files/file_util.h"
#include "base/logging.h"
#include "base/strings/stringprintf.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_split.h"
#include "base/strings/string_util.h"

static const char *kCpuSysfsDir = "/sys/devices/system/cpu";

using std::string;
using std::vector;

namespace thermald {

CpufreqDevice::CpufreqDevice(int cpu_id)
    : cpu_id_(cpu_id),
      sysfs_base_path_(base::StringPrintf("%s/cpu%d/cpufreq", kCpuSysfsDir,
                                          cpu_id)) {
}

bool CpufreqDevice::SetMaximumFrequency(int max_frequency) {
  base::FilePath sysfs_attr_path = sysfs_base_path_.Append("scaling_max_freq");
  if (!base::PathExists(sysfs_attr_path)) {
    LOG(ERROR) << "Failed to set maximum cpu frequency: "
               << sysfs_attr_path.value() << " does not exist";
    return false;
  }

  const string str(base::NumberToString(max_frequency));
  if (!base::WriteFile(sysfs_attr_path, str.c_str(), str.length())) {
    return false;
  }

  DLOG(INFO) << "Set maximum frequency of CPU " << cpu_id_ << " to "
             << (max_frequency / 1000) << " MHz";

  return true;
}

bool CpufreqDevice::GetAvailableFrequencies(
    vector<int> *available_frequencies) {
  DCHECK(available_frequencies);

  base::FilePath sysfs_attr_path(sysfs_base_path_.Append(
      "scaling_available_frequencies"));
  string str;
  if (!base::ReadFileToString(sysfs_attr_path, &str)) {
    LOG(ERROR) << "Failed to read from '" << sysfs_attr_path.value() << "'";
    return false;
  }
  base::TrimWhitespaceASCII(str, base::TRIM_TRAILING, &str);

  available_frequencies->clear();

  vector<string> frequency_strings =
      base::SplitString(str, " ", base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
  for (const string &frequency_string : frequency_strings) {
    int freq;
    base::StringToInt(frequency_string, &freq);
    available_frequencies->push_back(freq);
  }

  return true;
}

bool CpufreqDevice::GetDevices(
    std::vector<std::unique_ptr<CpufreqDevice>> *cpufreq_devices) {
  DCHECK(cpufreq_devices);

  base::FilePath cpufreq_sysfs_dir(string(kCpuSysfsDir) + "/cpufreq");
  if (!DirectoryExists(cpufreq_sysfs_dir)) {
    LOG(INFO) << "cpufreq is not enabled";
    return false;
  }

  base::FilePath cpu_sysfs_dir(kCpuSysfsDir);
  base::FileEnumerator enumerator(cpu_sysfs_dir, false,
                                  base::FileEnumerator::DIRECTORIES,
                                  FILE_PATH_LITERAL("cpu[0-9]*"));
  for (base::FilePath cpu = enumerator.Next(); !cpu.empty();
       cpu = enumerator.Next()) {
    int cpu_id;
    base::StringToInt(cpu.BaseName().value().substr(3), &cpu_id);
    cpufreq_devices->push_back(std::make_unique<CpufreqDevice>(cpu_id));
  }

  return true;
}

}  // namespace thermald