Revert of Use chromeos accelerometer reader and support only lid accelerometer. (patchset #3 id:60001 of https://codereview.chromium.org/574113002/)

Reason for revert:
Breaks ChromeOS compilation http://build.chromium.org/p/chromium.chromiumos/builders/Linux%20ChromiumOS%20Full/builds/11155/steps/compile/logs/stdio

Original issue's description:
> Use chromeos accelerometer reader in athena and support only lid accelerometer.
>
> BUG=380831
> TEST=Glimmer/clapper still work, manually tested not having a base accelerometer.
>
> Committed: https://crrev.com/2aa8d2e93a06cc7673c872704c04e933bd6cc252
> Cr-Commit-Position: refs/heads/master@{#295258}

TBR=derat@chromium.org,oshima@chromium.org,flackr@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=380831

Review URL: https://codereview.chromium.org/571283006

Cr-Commit-Position: refs/heads/master@{#295262}

2 files changed, 58 insertions, 96 deletions

diff --git a/chromeos/accelerometer/accelerometer_reader.cc b/chromeos/accelerometer/accelerometer_reader.cc
index ae5e6a6..24ec490 100644
--- a/chromeos/accelerometer/accelerometer_reader.cc
+++ b/chromeos/accelerometer/accelerometer_reader.cc
@@ -27,29 +27,28 @@ const base::FilePath::CharType kAccelerometerDevicePath[] =
 const base::FilePath::CharType kAccelerometerIioBasePath[] =
     FILE_PATH_LITERAL("/sys/bus/iio/devices/");
 
-// File within the device in kAccelerometerIioBasePath containing the scale of
+// Files within the device in kAccelerometerIioBasePath containing the scales of
 // the accelerometers.
-const base::FilePath::CharType kScaleNameFormatString[] = "in_accel_%s_scale";
+const base::FilePath::CharType kAccelerometerBaseScaleName[] =
+    FILE_PATH_LITERAL("in_accel_base_scale");
+const base::FilePath::CharType kAccelerometerLidScaleName[] =
+    FILE_PATH_LITERAL("in_accel_lid_scale");
 
 // 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 names of the accelerometers. Matches up with the enum AccelerometerSource
-// in ui/accelerometer/accelerometer_types.h.
-const char kAccelerometerNames[ui::ACCELEROMETER_SOURCE_COUNT][5] = {
-    "lid", "base"};
-
-// The axes on each accelerometer.
-const char kAccelerometerAxes[][2] = {"y", "x", "z"};
+// The names of the accelerometers and axes in the order we want to read them.
+const char kAccelerometerNames[][5] = {"base", "lid"};
+const char kAccelerometerAxes[][2] = {"x", "y", "z"};
+const size_t kTriggerDataValues =
+    arraysize(kAccelerometerNames) * arraysize(kAccelerometerAxes);
+const size_t kTriggerDataLength = kTriggerDataValues * 2;
 
 // 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 time to wait between reading the accelerometer.
 const int kDelayBetweenReadsMs = 100;
 
@@ -58,14 +57,15 @@ const float kMeanGravity = 9.80665f;
 
 // 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) {
+bool ReadFileToUint(const base::FilePath& path, unsigned int* value) {
   std::string s;
   DCHECK(value);
   if (!base::ReadFileToString(path, &s, kMaxAsciiUintLength)) {
+    LOG(ERROR) << "Failed to read " << path.value();
     return false;
   }
   base::TrimWhitespaceASCII(s, base::TRIM_ALL, &s);
-  if (!base::StringToInt(s, value)) {
+  if (!base::StringToUint(s, value)) {
     LOG(ERROR) << "Failed to parse \"" << s << "\" from " << path.value();
     return false;
   }
@@ -90,62 +90,41 @@ bool DetectAndReadAccelerometerConfiguration(
 
   base::FilePath iio_path(base::FilePath(kAccelerometerIioBasePath).Append(
       device));
-  // 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) {
-    // Read scale of accelerometer.
-    std::string accelerometer_scale_path = base::StringPrintf(
-        kScaleNameFormatString, kAccelerometerNames[i]);
-    int scale_divisor;
-    if (!ReadFileToInt(iio_path.Append(accelerometer_scale_path.c_str()),
-        &scale_divisor)) {
-      configuration->data.has[i] = false;
-      continue;
-    }
+  // Read accelerometer scales
+  if (!ReadFileToUint(iio_path.Append(kAccelerometerBaseScaleName),
+                      &(configuration->data.base_scale))) {
+    return false;
+  }
+  if (!ReadFileToUint(iio_path.Append(kAccelerometerLidScaleName),
+                      &(configuration->data.lid_scale))) {
+    return false;
+  }
 
-    configuration->data.has[i] = true;
-    configuration->data.count++;
+  // Read indices of each accelerometer axis from each accelerometer from
+  // /sys/bus/iio/devices/iio:deviceX/scan_elements/in_accel_{x,y,z}_%s_index
+  for (size_t i = 0; i < arraysize(kAccelerometerNames); ++i) {
     for (size_t j = 0; j < arraysize(kAccelerometerAxes); ++j) {
-      configuration->data.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->data.index[i][j]))) {
+      unsigned int index = 0;
+      if (!ReadFileToUint(iio_path.Append(accelerometer_index_path.c_str()),
+                          &index)) {
         return false;
       }
-    }
-  }
-
-  // Adjust the directions of accelerometers to match the AccelerometerUpdate
-  // type specified in ui/accelerometer/accelerometer_types.h.
-  configuration->data.scale[ui::ACCELEROMETER_SOURCE_SCREEN][0] *= -1.0f;
-  for (int i = 0; i < 3; ++i) {
-    configuration->data.scale[ui::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD][i] *=
-        -1.0f;
-  }
-
-  // Verify indices are within bounds.
-  for (int i = 0; i < ui::ACCELEROMETER_SOURCE_COUNT; ++i) {
-    if (!configuration->data.has[i])
-      continue;
-    for (int j = 0; j < 3; ++j) {
-      if (configuration->data.index[i][j] < 0 ||
-          configuration->data.index[i][j] >=
-              3 * static_cast<int>(configuration->data.count)) {
-        LOG(ERROR) << "Field index for " << kAccelerometerNames[i] << " "
-                   << kAccelerometerAxes[j] << " axis out of bounds.";
+      if (index >= kTriggerDataValues) {
+        LOG(ERROR) << "Field index from " << accelerometer_index_path
+                   << " out of bounds: " << index;
         return false;
       }
+      configuration->data.index.push_back(index);
     }
   }
-  configuration->data.length = kDataSize * 3 * configuration->data.count;
   return true;
 }
 
 bool ReadAccelerometer(
-    scoped_refptr<AccelerometerReader::Reading> reading,
-    size_t length) {
+    scoped_refptr<AccelerometerReader::Reading> reading) {
   // Initiate the trigger to read accelerometers simultaneously
   int bytes_written = base::WriteFile(
       base::FilePath(kAccelerometerTriggerPath), "1\n", 2);
@@ -156,10 +135,10 @@ bool ReadAccelerometer(
 
   // Read resulting sample from /dev/cros-ec-accel.
   int bytes_read = base::ReadFile(base::FilePath(kAccelerometerDevicePath),
-                                  reading->data, length);
-  if (bytes_read < static_cast<int>(length)) {
+                                  reading->data, kTriggerDataLength);
+  if (bytes_read < static_cast<int>(kTriggerDataLength)) {
     LOG(ERROR) << "Read " << bytes_read << " byte(s), expected "
-               << length << " bytes from accelerometer";
+               << kTriggerDataLength << " bytes from accelerometer";
     return false;
   }
   return true;
@@ -167,24 +146,16 @@ bool ReadAccelerometer(
 
 }  // namespace
 
-AccelerometerReader::ConfigurationData::ConfigurationData()
-    : count(0) {
-  for (int i = 0; i < ui::ACCELEROMETER_SOURCE_COUNT; ++i) {
-    has[i] = false;
-    for (int j = 0; j < 3; ++j) {
-      scale[i][j] = 0;
-      index[i][j] = -1;
-    }
-  }
+AccelerometerReader::ConfigurationData::ConfigurationData() {
 }
 
 AccelerometerReader::ConfigurationData::~ConfigurationData() {
 }
 
 AccelerometerReader::AccelerometerReader(
-    base::TaskRunner* blocking_task_runner,
+    base::TaskRunner* task_runner,
     AccelerometerReader::Delegate* delegate)
-    : task_runner_(blocking_task_runner),
+    : task_runner_(task_runner),
       delegate_(delegate),
       configuration_(new AccelerometerReader::Configuration()),
       weak_factory_(this) {
@@ -215,8 +186,7 @@ void AccelerometerReader::TriggerRead() {
       new AccelerometerReader::Reading());
   base::PostTaskAndReplyWithResult(task_runner_.get(),
                                    FROM_HERE,
-                                   base::Bind(&ReadAccelerometer, reading,
-                                              configuration_->data.length),
+                                   base::Bind(&ReadAccelerometer, reading),
                                    base::Bind(&AccelerometerReader::OnDataRead,
                                               weak_factory_.GetWeakPtr(),
                                               reading));
@@ -228,19 +198,17 @@ void AccelerometerReader::OnDataRead(
   DCHECK(!task_runner_->RunsTasksOnCurrentThread());
 
   if (success) {
-    for (int i = 0; i < ui::ACCELEROMETER_SOURCE_COUNT; ++i) {
-      if (!configuration_->data.has[i])
-        continue;
-
-      int16* values = reinterpret_cast<int16*>(reading->data);
-      update_.Set(static_cast<ui::AccelerometerSource>(i),
-                  values[configuration_->data.index[i][0]] *
-                      configuration_->data.scale[i][0],
-                  values[configuration_->data.index[i][1]] *
-                      configuration_->data.scale[i][1],
-                  values[configuration_->data.index[i][2]] *
-                      configuration_->data.scale[i][2]);
-    }
+    int16* values = reinterpret_cast<int16*>(reading->data);
+    float lid_scale = kMeanGravity / configuration_->data.lid_scale;
+    update_.Set(ui::ACCELEROMETER_SOURCE_SCREEN,
+                -values[configuration_->data.index[4]] * lid_scale,
+                values[configuration_->data.index[3]] * lid_scale,
+                values[configuration_->data.index[5]] * lid_scale);
+    float base_scale = kMeanGravity / configuration_->data.base_scale;
+    update_.Set(ui::ACCELEROMETER_SOURCE_ATTACHED_KEYBOARD,
+                -values[configuration_->data.index[1]] * base_scale,
+                -values[configuration_->data.index[0]] * base_scale,
+                -values[configuration_->data.index[2]] * base_scale);
     delegate_->HandleAccelerometerUpdate(update_);
   }
 
diff --git a/chromeos/accelerometer/accelerometer_reader.h b/chromeos/accelerometer/accelerometer_reader.h
index a66b12c..c3c4efd 100644
--- a/chromeos/accelerometer/accelerometer_reader.h
+++ b/chromeos/accelerometer/accelerometer_reader.h
@@ -5,6 +5,8 @@
 #ifndef CHROMEOS_ACCELEROMETER_ACCELEROMETER_READER_H_
 #define CHROMEOS_ACCELEROMETER_ACCELEROMETER_READER_H_
 
+#include <vector>
+
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
@@ -26,20 +28,12 @@ class CHROMEOS_EXPORT AccelerometerReader {
     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[ui::ACCELEROMETER_SOURCE_COUNT];
-
-    // Scale of accelerometers (i.e. raw value * scale = m/s^2).
-    float scale[ui::ACCELEROMETER_SOURCE_COUNT][3];
+    // Scale of accelerometers (i.e. raw value * 1.0f / scale = G's).
+    unsigned int base_scale;
+    unsigned int lid_scale;
 
     // Index of each accelerometer axis in data stream.
-    int index[ui::ACCELEROMETER_SOURCE_COUNT][3];
+    std::vector<unsigned int> index;
   };
   typedef base::RefCountedData<ConfigurationData> Configuration;
   typedef base::RefCountedData<char[12]> Reading;