Update AccelerometerReader to support separate iio devices

chromeos/accelerometer/accelerometer_reader.cc

 // Copyright 2014 The Chromium 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 "chromeos/accelerometer/accelerometer_reader.h"
 
+#include <algorithm>
 #include <string>
+#include <vector>
 
 #include "base/bind.h"
+#include "base/files/file_enumerator.h"
 #include "base/files/file_util.h"
 #include "base/location.h"
 #include "base/memory/singleton.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/task_runner.h"
 #include "base/task_runner_util.h"
 #include "base/thread_task_runner_handle.h"
 #include "base/threading/platform_thread.h"
 #include "base/threading/sequenced_worker_pool.h"
 
 namespace chromeos {
 
 namespace {
 
 // Paths to access necessary data from the accelerometer device.
 const base::FilePath::CharType kAccelerometerTriggerPath[] =
     FILE_PATH_LITERAL("/sys/bus/iio/devices/trigger0/trigger_now");
 const base::FilePath::CharType kAccelerometerDevicePath[] =
     FILE_PATH_LITERAL("/dev/cros-ec-accel");
 const base::FilePath::CharType kAccelerometerIioBasePath[] =
     FILE_PATH_LITERAL("/sys/bus/iio/devices/");
 
-// File within the device in kAccelerometerIioBasePath containing the scale of
-// the accelerometers.
-const base::FilePath::CharType kScaleFileName[] = "in_accel_scale";
-
 // This is the per source scale file in use on kernels older than 3.18. We
 // should remove this when all devices having accelerometers are on kernel 3.18
 // or later or have been patched to use new format: http://crbug.com/510831
 const base::FilePath::CharType kSourceScaleNameFormatString[] =
     "in_accel_%s_scale";
 
+// File within kAccelerometerDevicePath/device* which denotes a single scale to
+// be used across all axes.
+const base::FilePath::CharType kAccelerometerScaleFileName[] = "scale";
+
+// File within kAccelerometerDevicePath/device* which denotes the
+// AccelerometerSource for the accelerometer.
+const base::FilePath::CharType kAccelerometerLocationFileName[] = "location";
+
 // The filename giving the path to read the scan index of each accelerometer
 // axis.
 const char kAccelerometerScanIndexPath[] =
     "scan_elements/in_accel_%s_%s_index";
 
+// The filename giving the path to read the scan index of each accelerometer
+// when they are separate device paths.
+const char kSeparateAccelerometerScanIndexPath[] =

[flackr, 2015/08/27 16:24:22]

nit: Let's consistently call variables only relevant to the old paths "Legacy".
SeperateAccelerometer and Unified makes it seem like the two need to be
simultaneously supported. This will also make it more evident what can be
removed / moved to a separate file if we split this up.

[jonross, 2015/08/27 21:17:45]

Done.

+    "scan_elements/in_accel_%s_index";
+
 // The names of the accelerometers. Matches up with the enum AccelerometerSource
 // in chromeos/accelerometer/accelerometer_types.h.
 const char kAccelerometerNames[ACCELEROMETER_SOURCE_COUNT][5] = {"lid", "base"};
 
 // The axes on each accelerometer.
-const char kAccelerometerAxes[][2] = {"y", "x", "z"};
+const char kSeparateAccelerometerAxes[][2] = {"x", "y", "z"};
+const char kUnifiedAccelerometerAxes[][2] = {"y", "x", "z"};
 
 // The length required to read uint values from configuration files.
 const size_t kMaxAsciiUintLength = 21;
 
 // The size of individual values.
 const size_t kDataSize = 2;
 
+// The size of reading values for an entire accelerometer, when they are
+// separate device paths.
+const size_t kDataSizeForSeparateDevices = 6;

[flackr, 2015/08/27 16:24:22]

This is technically the reading size regardless of if they're separate or not.

Use a formula here to show what it comes from: e.g. kDataSize * kNumberOfAxes

[jonross, 2015/08/27 21:17:45]

Done.

+
 // The mean acceleration due to gravity on Earth in m/s^2.
 const float kMeanGravity = 9.80665f;
 
 // The number of accelerometers.
 const int kNumberOfAccelerometers = 2;
 
 // The number of axes for which there are acceleration readings.
 const int kNumberOfAxes = 3;
 
 // The size of data in one reading of the accelerometers.

[flackr, 2015/08/27 16:24:21]

nit: This (and above) should be the "maximum" size. We only actually use this
for the buffer size to read into but there can actually be fewer accelerometers
and we only actually read reading_data.length bytes.

[jonross, 2015/08/27 21:17:45]

Merged with above to represent the size of one read, and calculated vs the
length of reading_data.sources.

 const int kSizeOfReading = kDataSize * kNumberOfAccelerometers * kNumberOfAxes;
 
 // Reads |path| to the unsigned int pointed to by |value|. Returns true on
 // success or false on failure.
 bool ReadFileToInt(const base::FilePath& path, int* value) {
   std::string s;
   DCHECK(value);
   if (!base::ReadFileToString(path, &s, kMaxAsciiUintLength)) {
     return false;
   }
   base::TrimWhitespaceASCII(s, base::TRIM_ALL, &s);
   if (!base::StringToInt(s, value)) {
-    LOG(ERROR) << "Failed to parse \"" << s << "\" from " << path.value();
+    LOG(ERROR) << "Failed to parse int \"" << s << "\" from " << path.value();
     return false;
   }
   return true;
+}
+
+// Reads |path| to the double pointed to by |value|. Returns true on success or
+// false on failure.
+bool ReadFileToDouble(const base::FilePath& path, double* value) {
+  std::string s;
+  DCHECK(value);
+  if (!base::ReadFileToString(path, &s)) {
+    return false;
+  }
+  base::TrimWhitespaceASCII(s, base::TRIM_ALL, &s);
+  if (!base::StringToDouble(s, value)) {
+    LOG(ERROR) << "Failed to parse double \"" << s << "\" from "
+               << path.value();
+    return false;
+  }
+  return true;
 }
 
 }  // namespace
 
 const int AccelerometerReader::kDelayBetweenReadsMs = 100;
 
 // Work that runs on a base::TaskRunner. It determines the accelerometer
 // configuartion, and reads the data. Upon a successful read it will notify
 // all observers.
 class AccelerometerFileReader
@@ skipping 11 matching lines @@
   // read at the current sampling rate.
   void Read();
 
   // Add/Remove observers.
   void AddObserver(AccelerometerReader::Observer* observer);
   void RemoveObserver(AccelerometerReader::Observer* observer);
 
  private:
   friend class base::RefCountedThreadSafe<AccelerometerFileReader>;
 
+  // Represents necessary information in order to read an accelerometer device.
+  struct ReadingData {
+    // The full path to the accelerometer device to read.
+    base::FilePath path;
+
+    // The length of accelerometer updates to be read.
+    size_t length;
+
+    // All readings are placed in the same buffer, this is the offset to begin
+    // reading into for this accelerometer.
+    size_t offset;
+  };
+
   // Configuration structure for accelerometer device.
   struct ConfigurationData {
     ConfigurationData();
     ~ConfigurationData();
 
     // Number of accelerometers on device.
     size_t count;
 
-    // Length of accelerometer updates.
-    size_t length;
-
     // Which accelerometers are present on device.
     bool has[ACCELEROMETER_SOURCE_COUNT];
 
     // Scale of accelerometers (i.e. raw value * scale = m/s^2).
     float scale[ACCELEROMETER_SOURCE_COUNT][3];
 
     // Index of each accelerometer axis in data stream.
     int index[ACCELEROMETER_SOURCE_COUNT][3];
+
+    // The information for each accelerometer device to be read. In kernel 3.18
+    // there is one per ACCELEROMETER_SOURCE_COUNT, on 3.14 there is only one.
+    std::vector<ReadingData> reading_data;
   };
 
   ~AccelerometerFileReader() {}
 
+  // When accelerometers are presented as separate iio_devices this will perform
+  // the initialize for one of the devices, at the given |iio_path| and the
+  // symbolic link |name|. |location| is defined by AccelerometerSoure.
+  bool InitializeAccelerometer(const base::FilePath& iio_path,
+                               const base::FilePath& name,
+                               const std::string& location);
+
+  // When accelerometers are presented as a single iio_device this will perform
+  // the initialization for both of them.
+  bool InitializeLegacyAccelerometers(const base::FilePath& iio_path,
+                                      const base::FilePath& name);
+
   // Attempts to read the accelerometer data. Upon a success, converts the raw
   // reading to an AccelerometerUpdate and notifies observers.
   void ReadFileAndNotify();
 
   // True if Initialize completed successfully, and there is an accelerometer
   // file to read.
   bool initialization_successful_;
 
   // The accelerometer configuration.
   ConfigurationData configuration_;
@@ skipping 19 matching lines @@
 
 void AccelerometerFileReader::Initialize(
     scoped_refptr<base::SequencedTaskRunner> sequenced_task_runner) {
   DCHECK(
       base::SequencedWorkerPool::GetSequenceTokenForCurrentThread().IsValid());
   task_runner_ = sequenced_task_runner;
 
   // Check for accelerometer symlink which will be created by the udev rules
   // file on detecting the device.
   base::FilePath device;
-  if (!base::ReadSymbolicLink(base::FilePath(kAccelerometerDevicePath),
-                              &device)) {
+
+  if (base::IsDirectoryEmpty(base::FilePath(kAccelerometerDevicePath))) {
+    LOG(ERROR) << "Accelerometer device directory is empty at "
+               << kAccelerometerDevicePath;
     return;
   }
 
   if (!base::PathExists(base::FilePath(kAccelerometerTriggerPath))) {
     LOG(ERROR) << "Accelerometer trigger does not exist at"
                << kAccelerometerTriggerPath;
     return;
   }
 
-  base::FilePath iio_path(base::FilePath(kAccelerometerIioBasePath).Append(
-      device));
-
-  // Read the scale for all axes.
-  int scale_divisor = 0;
-  bool per_source_scale =
-      !ReadFileToInt(iio_path.Append(kScaleFileName), &scale_divisor);
-  if (!per_source_scale && scale_divisor == 0) {
-    LOG(ERROR) << "Accelerometer " << kScaleFileName
-               << "has scale of 0 and will not be used.";
-    return;
-  }
-
-  // Read configuration of each accelerometer axis from each accelerometer from
-  // /sys/bus/iio/devices/iio:deviceX/.
-  for (size_t i = 0; i < arraysize(kAccelerometerNames); ++i) {
-    if (per_source_scale) {
-      configuration_.has[i] = false;
-      // Read scale of accelerometer.
-      std::string accelerometer_scale_path = base::StringPrintf(
-          kSourceScaleNameFormatString, kAccelerometerNames[i]);
-      if (!ReadFileToInt(iio_path.Append(accelerometer_scale_path.c_str()),
-                         &scale_divisor)) {
-        continue;
-      }
-      if (scale_divisor == 0) {
-        LOG(ERROR) << "Accelerometer " << accelerometer_scale_path
-                   << "has scale of 0 and will not be used.";
-        continue;
-      }
+  base::FileEnumerator symlink_dir(base::FilePath(kAccelerometerDevicePath),
+                                   false, base::FileEnumerator::FILES);
+  bool separate_devices = false;
+  for (base::FilePath name = symlink_dir.Next(); !name.empty();
+       name = symlink_dir.Next()) {
+    base::FilePath iio_device;
+    if (!base::ReadSymbolicLink(name, &iio_device)) {
+      LOG(ERROR) << "Failed to read symbolic link " << kAccelerometerDevicePath
+                 << "/" << name.MaybeAsASCII() << "\n";
+      return;
     }
 
-    configuration_.has[i] = true;
-    for (size_t j = 0; j < arraysize(kAccelerometerAxes); ++j) {
-      configuration_.scale[i][j] = kMeanGravity / scale_divisor;
-      std::string accelerometer_index_path = base::StringPrintf(
-          kAccelerometerScanIndexPath, kAccelerometerAxes[j],
-          kAccelerometerNames[i]);
-      if (!ReadFileToInt(iio_path.Append(accelerometer_index_path.c_str()),
-                         &(configuration_.index[i][j]))) {
-        configuration_.has[i] = false;
-        break;
-      }
+    base::FilePath iio_path(base::FilePath(kAccelerometerIioBasePath)
+                                .Append(iio_device.BaseName()));
+    std::string location;
+    separate_devices = base::ReadFileToString(
+        base::FilePath(iio_path).Append(kAccelerometerLocationFileName),
+        &location);
+    if (separate_devices) {
+      base::TrimWhitespaceASCII(location, base::TRIM_ALL, &location);
+      if (!InitializeAccelerometer(iio_path, name, location))
+        return;
+    } else {
+      if (!InitializeLegacyAccelerometers(iio_path, name))
+        return;
     }
-    if (configuration_.has[i])
-      configuration_.count++;
-  }
-
-  // Adjust the directions of accelerometers to match the AccelerometerUpdate
-  // type specified in chromeos/accelerometer/accelerometer_types.h.
-  configuration_.scale[ACCELEROMETER_SOURCE_SCREEN][0] *= -1.0f;
-  for (int i = 0; i < 3; ++i) {
-    configuration_.scale[ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD][i] *= -1.0f;
   }
 
   // Verify indices are within bounds.
   for (int i = 0; i < ACCELEROMETER_SOURCE_COUNT; ++i) {
     if (!configuration_.has[i])
       continue;
     for (int j = 0; j < 3; ++j) {
       if (configuration_.index[i][j] < 0 ||
           configuration_.index[i][j] >=
               3 * static_cast<int>(configuration_.count)) {
+        const char* axis = separate_devices ? kSeparateAccelerometerAxes[j]
+                                            : kUnifiedAccelerometerAxes[j];
         LOG(ERROR) << "Field index for " << kAccelerometerNames[i] << " "
-                   << kAccelerometerAxes[j] << " axis out of bounds.";
+                   << axis << " axis out of bounds.";
         return;
       }
     }
   }
-  configuration_.length = kDataSize * 3 * configuration_.count;
+
   initialization_successful_ = true;
   Read();
 }
 
 void AccelerometerFileReader::Read() {
   DCHECK(
       base::SequencedWorkerPool::GetSequenceTokenForCurrentThread().IsValid());
   ReadFileAndNotify();
   task_runner_->PostNonNestableDelayedTask(
       FROM_HERE, base::Bind(&AccelerometerFileReader::Read, this),
       base::TimeDelta::FromMilliseconds(
           AccelerometerReader::kDelayBetweenReadsMs));
 }
 
 void AccelerometerFileReader::AddObserver(
     AccelerometerReader::Observer* observer) {
   observers_->AddObserver(observer);
   if (initialization_successful_) {
     task_runner_->PostNonNestableTask(
         FROM_HERE,
         base::Bind(&AccelerometerFileReader::ReadFileAndNotify, this));
   }
 }
 
 void AccelerometerFileReader::RemoveObserver(
     AccelerometerReader::Observer* observer) {
   observers_->RemoveObserver(observer);
 }
 
+bool AccelerometerFileReader::InitializeAccelerometer(
+    const base::FilePath& iio_path,
+    const base::FilePath& name,
+    const std::string& location) {
+  int config_index = std::find(std::begin(kAccelerometerNames),
+                               std::end(kAccelerometerNames), location) -
+                     std::begin(kAccelerometerNames);
+  if (config_index == -1) {
+    LOG(ERROR) << "Unrecognized location: " << location << " for device "
+               << name.MaybeAsASCII() << "\n";
+    return false;
+  }
+
+  double scale;
+  if (!ReadFileToDouble(iio_path.Append(kAccelerometerScaleFileName), &scale))
+    return false;
+
+  const int number_axes = arraysize(kSeparateAccelerometerAxes);
+  for (size_t j = 0; j < number_axes; ++j) {
+    std::string accelerometer_index_path = base::StringPrintf(
+        kSeparateAccelerometerScanIndexPath, kSeparateAccelerometerAxes[j]);
+    if (!ReadFileToInt(iio_path.Append(accelerometer_index_path.c_str()),
+                       &(configuration_.index[config_index][j]))) {
+      LOG(ERROR) << "Index file " << accelerometer_index_path
+                 << " could not be parsed\n";
+      return false;
+    }
+    configuration_.index[config_index][j] += config_index * number_axes;
+    configuration_.scale[config_index][j] = scale;
+  }
+  configuration_.has[config_index] = true;
+  configuration_.count++;
+
+  ReadingData reading_data;
+  reading_data.path =
+      base::FilePath(kAccelerometerDevicePath).Append(name.BaseName());
+  reading_data.offset = config_index * kDataSizeForSeparateDevices;
+  reading_data.length = kDataSizeForSeparateDevices;
+
+  configuration_.reading_data.push_back(reading_data);
+
+  return true;
+}
+
+bool AccelerometerFileReader::InitializeLegacyAccelerometers(
+    const base::FilePath& iio_path,
+    const base::FilePath& name) {
+  // Read the scale for all axes.
+  int scale_divisor = 0;
+  // Read configuration of each accelerometer axis from each accelerometer from
+  // /sys/bus/iio/devices/iio:deviceX/.
+  for (size_t i = 0; i < arraysize(kAccelerometerNames); ++i) {
+    configuration_.has[i] = false;
+    // Read scale of accelerometer.
+    std::string accelerometer_scale_path = base::StringPrintf(
+        kSourceScaleNameFormatString, kAccelerometerNames[i]);
+    if (!ReadFileToInt(iio_path.Append(accelerometer_scale_path.c_str()),
+                       &scale_divisor)) {
+      continue;
+    }
+    if (scale_divisor == 0) {
+      LOG(ERROR) << "Accelerometer " << accelerometer_scale_path
+                 << "has scale of 0 and will not be used.";
+      continue;
+    }
+
+    configuration_.has[i] = true;
+    for (size_t j = 0; j < arraysize(kUnifiedAccelerometerAxes); ++j) {
+      configuration_.scale[i][j] = kMeanGravity / scale_divisor;
+      std::string accelerometer_index_path = base::StringPrintf(
+          kAccelerometerScanIndexPath, kUnifiedAccelerometerAxes[j],
+          kAccelerometerNames[i]);
+      if (!ReadFileToInt(iio_path.Append(accelerometer_index_path.c_str()),
+                         &(configuration_.index[i][j]))) {
+        configuration_.has[i] = false;
+        LOG(ERROR) << "Index file " << accelerometer_index_path
+                   << " could not be parsed\n";
+        return false;
+      }
+    }
+    if (configuration_.has[i])
+      configuration_.count++;
+  }
+
+  // Adjust the directions of accelerometers to match the AccelerometerUpdate
+  // type specified in chromeos/accelerometer/accelerometer_types.h.
+  configuration_.scale[ACCELEROMETER_SOURCE_SCREEN][1] *= -1.0f;
+  configuration_.scale[ACCELEROMETER_SOURCE_SCREEN][2] *= -1.0f;
+
+  ReadingData reading_data;
+  reading_data.path =
+      base::FilePath(kAccelerometerDevicePath).Append(name.BaseName());
+  reading_data.offset = 0;
+  reading_data.length = kDataSize * 3 * configuration_.count;
+
+  configuration_.reading_data.push_back(reading_data);
+  return true;
+}
+
 void AccelerometerFileReader::ReadFileAndNotify() {
   DCHECK(initialization_successful_);
-  char reading[kSizeOfReading];
 
   // Initiate the trigger to read accelerometers simultaneously
   int bytes_written = base::WriteFile(
       base::FilePath(kAccelerometerTriggerPath), "1\n", 2);
   if (bytes_written < 2) {
     PLOG(ERROR) << "Accelerometer trigger failure: " << bytes_written;
     return;
   }
 
   // Read resulting sample from /dev/cros-ec-accel.
-  int bytes_read = base::ReadFile(base::FilePath(kAccelerometerDevicePath),
-                                  reading, configuration_.length);
-  if (bytes_read < static_cast<int>(configuration_.length)) {
-    LOG(ERROR) << "Read " << bytes_read << " byte(s), expected "
-               << configuration_.length << " bytes from accelerometer";
-    return;
+  char reading[kSizeOfReading];
+  int bytes_read;
+  for (auto reading_data : configuration_.reading_data) {
+    bytes_read = base::ReadFile(
+        reading_data.path, reading + reading_data.offset, reading_data.length);
+    if (bytes_read < static_cast<int>(reading_data.length)) {
+      LOG(ERROR) << "Accelerometer Read " << bytes_read << " byte(s), expected "
+                 << reading_data.length << " bytes from accelerometer "
+                 << reading_data.path.MaybeAsASCII();
+      return;
+    }
   }
 
   update_ = new AccelerometerUpdate();
 
   for (int i = 0; i < ACCELEROMETER_SOURCE_COUNT; ++i) {
     if (!configuration_.has[i])
       continue;
 
     int16* values = reinterpret_cast<int16*>(reading);
     update_->Set(
@@ skipping 46 matching lines @@
 }
 
 AccelerometerReader::AccelerometerReader()
     : accelerometer_file_reader_(new AccelerometerFileReader()) {
 }
 
 AccelerometerReader::~AccelerometerReader() {
 }
 
 }  // namespace chromeos