Add gamepad data fetcher for Linux

BUG=79050

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=116724

Review URL: http://codereview.chromium.org/8899017

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@116752 0039d316-1c4b-4281-b951-d872f2087c98

14 files changed, 603 insertions, 71 deletions

diff --git a/build/linux/system.gyp b/build/linux/system.gyp
index 90c8b45..cc50d59 100644
--- a/build/linux/system.gyp
+++ b/build/linux/system.gyp
@@ -625,5 +625,26 @@
         }],
       ],
     },
+    {
+      'target_name': 'udev',
+      'type': 'none',
+      'conditions': [
+        ['_toolset=="target"', {
+          'direct_dependent_settings': {
+            'cflags': [
+              '<!@(<(pkg-config) --cflags libudev)'
+            ],
+          },
+          'link_settings': {
+            'ldflags': [
+              '<!@(<(pkg-config) --libs-only-L --libs-only-other libudev)',
+            ],
+            'libraries': [
+              '<!@(<(pkg-config) --libs-only-l libudev)',
+            ],
+          },
+        }],
+      ],
+    },
   ],
 }
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 6517f87..7fdf402 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -470,7 +470,7 @@ const Experiment kExperiments[] = {
     "enable-gamepad",
     IDS_FLAGS_ENABLE_GAMEPAD_NAME,
     IDS_FLAGS_ENABLE_GAMEPAD_DESCRIPTION,
-    kOsMac | kOsWin,
+    kOsAll,
     SINGLE_VALUE_TYPE(switches::kEnableGamepad)
   },
 #if defined(USE_AURA)
diff --git a/content/browser/gamepad/gamepad_provider.cc b/content/browser/gamepad/gamepad_provider.cc
index 29492fa..4c00cc1 100644
--- a/content/browser/gamepad/gamepad_provider.cc
+++ b/content/browser/gamepad/gamepad_provider.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 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.
 
@@ -11,41 +11,14 @@
 #include "base/message_loop.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_restrictions.h"
-#include "content/public/browser/browser_thread.h"
-#include "content/browser/gamepad/gamepad_provider.h"
 #include "content/browser/gamepad/data_fetcher.h"
+#include "content/browser/gamepad/gamepad_provider.h"
+#include "content/browser/gamepad/platform_data_fetcher.h"
 #include "content/common/gamepad_messages.h"
-
-#if defined(OS_WIN)
-#include "content/browser/gamepad/data_fetcher_win.h"
-#elif defined(OS_MACOSX)
-#include "content/browser/gamepad/data_fetcher_mac.h"
-#endif
+#include "content/public/browser/browser_thread.h"
 
 namespace content {
 
-// Define the default data fetcher that GamepadProvider will use if none is
-// supplied. (GamepadPlatformDataFetcher).
-#if defined(OS_WIN)
-
-typedef GamepadDataFetcherWindows GamepadPlatformDataFetcher;
-
-#elif defined(OS_MACOSX)
-
-typedef GamepadDataFetcherMac GamepadPlatformDataFetcher;
-
-#else
-
-class GamepadEmptyDataFetcher : public GamepadDataFetcher {
- public:
-  void GetGamepadData(WebKit::WebGamepads* pads, bool) {
-    pads->length = 0;
-  }
-};
-typedef GamepadEmptyDataFetcher GamepadPlatformDataFetcher;
-
-#endif
-
 GamepadProvider::GamepadProvider(GamepadDataFetcher* fetcher)
     : is_paused_(false),
       devices_changed_(true),
@@ -61,7 +34,8 @@ GamepadProvider::GamepadProvider(GamepadDataFetcher* fetcher)
   memset(hwbuf, 0, sizeof(GamepadHardwareBuffer));
 
   polling_thread_.reset(new base::Thread("Gamepad polling thread"));
-  polling_thread_->Start();
+  polling_thread_->StartWithOptions(
+      base::Thread::Options(MessageLoop::TYPE_IO, 0));
 
   MessageLoop* polling_loop = polling_thread_->message_loop();
   polling_loop->PostTask(
diff --git a/content/browser/gamepad/gamepad_provider.h b/content/browser/gamepad/gamepad_provider.h
index f0e25de..b1bdb74 100644
--- a/content/browser/gamepad/gamepad_provider.h
+++ b/content/browser/gamepad/gamepad_provider.h
@@ -1,9 +1,9 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 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.
 
-#ifndef CONTENT_BROWSER_GAMEPAD_PROVIDER_H_
-#define CONTENT_BROWSER_GAMEPAD_PROVIDER_H_
+#ifndef CONTENT_BROWSER_GAMEPAD_GAMEPAD_PROVIDER_H_
+#define CONTENT_BROWSER_GAMEPAD_GAMEPAD_PROVIDER_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
@@ -88,4 +88,4 @@ class CONTENT_EXPORT GamepadProvider :
 
 }  // namespace content
 
-#endif  // CONTENT_BROWSER_GAMEPAD_PROVIDER_H_
+#endif  // CONTENT_BROWSER_GAMEPAD_GAMEPAD_PROVIDER_H_
diff --git a/content/browser/gamepad/gamepad_standard_mappings_linux.cc b/content/browser/gamepad/gamepad_standard_mappings_linux.cc
new file mode 100644
index 0000000..99d9ba7
--- /dev/null
+++ b/content/browser/gamepad/gamepad_standard_mappings_linux.cc
@@ -0,0 +1,156 @@
+// Copyright (c) 2012 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 "content/browser/gamepad/gamepad_standard_mappings_linux.h"
+
+#include "content/common/gamepad_hardware_buffer.h"
+
+namespace content {
+
+namespace {
+
+// This defines our canonical mapping order for gamepad-like devices. If these
+// items cannot all be satisfied, it is a case-by-case judgement as to whether
+// it is better to leave the device unmapped, or to partially map it. In
+// general, err towards leaving it *unmapped* so that content can handle
+// appropriately.
+
+enum CanonicalButtonIndex {
+  kButtonPrimary,
+  kButtonSecondary,
+  kButtonTertiary,
+  kButtonQuaternary,
+  kButtonLeftShoulder,
+  kButtonRightShoulder,
+  kButtonLeftTrigger,
+  kButtonRightTrigger,
+  kButtonBackSelect,
+  kButtonStart,
+  kButtonLeftThumbstick,
+  kButtonRightThumbstick,
+  kButtonDpadUp,
+  kButtonDpadDown,
+  kButtonDpadLeft,
+  kButtonDpadRight,
+  kButtonMeta,
+  kNumButtons
+};
+
+enum CanonicalAxisIndex {
+  kAxisLeftStickX,
+  kAxisLeftStickY,
+  kAxisRightStickX,
+  kAxisRightStickY,
+  kNumAxes
+};
+
+float AxisToButton(float input) {
+  return (input + 1.f) / 2.f;
+}
+
+float AxisNegativeAsButton(float input) {
+  return (input < -0.5f) ? 1.f : 0.f;
+}
+
+float AxisPositiveAsButton(float input) {
+  return (input > 0.5f) ? 1.f : 0.f;
+}
+
+void MapperXInputStyleGamepad(
+    const WebKit::WebGamepad& input,
+    WebKit::WebGamepad* mapped) {
+  *mapped = input;
+  mapped->buttons[kButtonLeftTrigger] = AxisToButton(input.axes[2]);
+  mapped->buttons[kButtonRightTrigger] = AxisToButton(input.axes[5]);
+  mapped->buttons[kButtonBackSelect] = input.buttons[6];
+  mapped->buttons[kButtonStart] = input.buttons[7];
+  mapped->buttons[kButtonLeftThumbstick] = input.buttons[9];
+  mapped->buttons[kButtonRightThumbstick] = input.buttons[10];
+  mapped->buttons[kButtonDpadUp] = AxisNegativeAsButton(input.axes[7]);
+  mapped->buttons[kButtonDpadDown] = AxisPositiveAsButton(input.axes[7]);
+  mapped->buttons[kButtonDpadLeft] = AxisNegativeAsButton(input.axes[6]);
+  mapped->buttons[kButtonDpadRight] = AxisPositiveAsButton(input.axes[6]);
+  mapped->buttons[kButtonMeta] = input.buttons[8];
+  mapped->axes[kAxisRightStickX] = input.axes[3];
+  mapped->axes[kAxisRightStickY] = input.axes[4];
+  mapped->buttonsLength = kNumButtons;
+  mapped->axesLength = kNumAxes;
+}
+
+void MapperMP8866(
+    const WebKit::WebGamepad& input,
+    WebKit::WebGamepad* mapped) {
+  *mapped = input;
+  mapped->buttons[kButtonPrimary] = input.buttons[2];
+  mapped->buttons[kButtonTertiary] = input.buttons[3];
+  mapped->buttons[kButtonQuaternary] = input.buttons[0];
+  mapped->buttons[kButtonLeftShoulder] = input.buttons[6];
+  mapped->buttons[kButtonRightShoulder] = input.buttons[7];
+  mapped->buttons[kButtonLeftTrigger] = input.buttons[4];
+  mapped->buttons[kButtonRightTrigger] = input.buttons[5];
+  mapped->buttons[kButtonBackSelect] = input.buttons[9];
+  mapped->buttons[kButtonStart] = input.buttons[8];
+  mapped->buttons[kButtonDpadUp] = AxisNegativeAsButton(input.axes[5]);
+  mapped->buttons[kButtonDpadDown] = AxisPositiveAsButton(input.axes[5]);
+  mapped->buttons[kButtonDpadLeft] = AxisNegativeAsButton(input.axes[4]);
+  mapped->buttons[kButtonDpadRight] = AxisPositiveAsButton(input.axes[4]);
+  mapped->buttonsLength = kNumButtons - 1; // no Meta on this device
+  mapped->axesLength = kNumAxes;
+}
+
+void MapperPlaystationSixAxis(
+    const WebKit::WebGamepad& input,
+    WebKit::WebGamepad* mapped) {
+  *mapped = input;
+  mapped->buttons[kButtonPrimary] = input.buttons[14];
+  mapped->buttons[kButtonSecondary] = input.buttons[13];
+  mapped->buttons[kButtonTertiary] = input.buttons[15];
+  mapped->buttons[kButtonQuaternary] = input.buttons[12];
+  mapped->buttons[kButtonLeftShoulder] = input.buttons[10];
+  mapped->buttons[kButtonRightShoulder] = input.buttons[11];
+  mapped->buttons[kButtonLeftTrigger] = AxisToButton(input.axes[12]);
+  mapped->buttons[kButtonRightTrigger] = AxisToButton(input.axes[13]);
+  mapped->buttons[kButtonBackSelect] = input.buttons[0];
+  mapped->buttons[kButtonStart] = input.buttons[3];
+  mapped->buttons[kButtonLeftThumbstick] = input.buttons[1];
+  mapped->buttons[kButtonRightThumbstick] = input.buttons[2];
+  mapped->buttons[kButtonDpadUp] = AxisToButton(input.axes[8]);
+  mapped->buttons[kButtonDpadDown] = AxisToButton(input.axes[10]);
+  mapped->buttons[kButtonDpadLeft] = input.buttons[7];
+  mapped->buttons[kButtonDpadRight] = AxisToButton(input.axes[9]);
+  mapped->buttons[kButtonMeta] = input.buttons[16];
+
+  mapped->buttonsLength = kNumButtons;
+  mapped->axesLength = kNumAxes;
+}
+
+struct MappingData {
+  const char* const vendor_id;
+  const char* const product_id;
+  GamepadStandardMappingFunction function;
+} AvailableMappings[] = {
+  // http://www.linux-usb.org/usb.ids
+  { "045e", "028e", MapperXInputStyleGamepad }, // Xbox 360 Controller
+  { "045e", "028f", MapperXInputStyleGamepad }, // Xbox 360 Wireless Controller
+  { "046d", "c21d", MapperXInputStyleGamepad }, // Logitech F310
+  { "046d", "c21e", MapperXInputStyleGamepad }, // Logitech F510
+  { "046d", "c21f", MapperXInputStyleGamepad }, // Logitech F710
+  { "054c", "0268", MapperPlaystationSixAxis }, // Playstation SIXAXIS
+  { "0925", "8866", MapperMP8866 }, // WiseGroup MP-8866
+};
+
+}  // namespace
+
+GamepadStandardMappingFunction GetGamepadStandardMappingFunction(
+    const base::StringPiece& vendor_id,
+    const base::StringPiece& product_id) {
+  for (size_t i = 0; i < arraysize(AvailableMappings); ++i) {
+    MappingData& item = AvailableMappings[i];
+    if (vendor_id == item.vendor_id && product_id == item.product_id)
+      return item.function;
+  }
+  return NULL;
+}
+
+}  // namespace content
diff --git a/content/browser/gamepad/gamepad_standard_mappings_linux.h b/content/browser/gamepad/gamepad_standard_mappings_linux.h
new file mode 100644
index 0000000..6d06fc6
--- /dev/null
+++ b/content/browser/gamepad/gamepad_standard_mappings_linux.h
@@ -0,0 +1,26 @@
+// Copyright (c) 2012 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.
+
+#ifndef CONTENT_BROWSER_GAMEPAD_GAMEPAD_STANDARD_MAPPINGS_LINUX_H_
+#define CONTENT_BROWSER_GAMEPAD_GAMEPAD_STANDARD_MAPPINGS_LINUX_H_
+
+#include "base/string_piece.h"
+
+namespace WebKit {
+class WebGamepad;
+}
+
+namespace content {
+
+typedef void (*GamepadStandardMappingFunction)(
+    const WebKit::WebGamepad& original,
+    WebKit::WebGamepad* mapped);
+
+GamepadStandardMappingFunction GetGamepadStandardMappingFunction(
+    const base::StringPiece& vendor_id,
+    const base::StringPiece& product_id);
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_GAMEPAD_GAMEPAD_STANDARD_MAPPINGS_LINUX_H_
diff --git a/content/browser/gamepad/platform_data_fetcher.h b/content/browser/gamepad/platform_data_fetcher.h
new file mode 100644
index 0000000..b9f64af
--- /dev/null
+++ b/content/browser/gamepad/platform_data_fetcher.h
@@ -0,0 +1,47 @@
+// Copyright (c) 2012 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.
+
+// Define the default data fetcher that GamepadProvider will use if none is
+// supplied. (GamepadPlatformDataFetcher).
+
+#ifndef CONTENT_BROWSER_GAMEPAD_PLATFORM_DATA_FETCHER_H_
+#define CONTENT_BROWSER_GAMEPAD_PLATFORM_DATA_FETCHER_H_
+
+#if defined(OS_WIN)
+#include "content/browser/gamepad/platform_data_fetcher_win.h"
+#elif defined(OS_MACOSX)
+#include "content/browser/gamepad/platform_data_fetcher_mac.h"
+#elif defined(OS_LINUX)
+#include "content/browser/gamepad/platform_data_fetcher_linux.h"
+#endif
+
+namespace content {
+
+#if defined(OS_WIN)
+
+typedef GamepadPlatformDataFetcherWin GamepadPlatformDataFetcher;
+
+#elif defined(OS_MACOSX)
+
+typedef GamepadPlatformDataFetcherMac GamepadPlatformDataFetcher;
+
+#elif defined(OS_LINUX)
+
+typedef GamepadPlatformDataFetcherLinux GamepadPlatformDataFetcher;
+
+#else
+
+class GamepadDataFetcherEmpty : public GamepadDataFetcher {
+ public:
+  void GetGamepadData(WebKit::WebGamepads* pads, bool) {
+    pads->length = 0;
+  }
+};
+typedef GamepadDataFetcherEmpty GamepadPlatformDataFetcher;
+
+#endif
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_GAMEPAD_PLATFORM_DATA_FETCHER_H_
diff --git a/content/browser/gamepad/platform_data_fetcher_linux.cc b/content/browser/gamepad/platform_data_fetcher_linux.cc
new file mode 100644
index 0000000..9c2a6bf
--- /dev/null
+++ b/content/browser/gamepad/platform_data_fetcher_linux.cc
@@ -0,0 +1,228 @@
+// Copyright (c) 2012 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 "content/browser/gamepad/platform_data_fetcher_linux.h"
+
+#include <dlfcn.h>
+#include <fcntl.h>
+#include <libudev.h>
+#include <linux/joystick.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include "base/debug/trace_event.h"
+#include "base/eintr_wrapper.h"
+#include "base/message_loop.h"
+#include "base/string_number_conversions.h"
+#include "base/stringprintf.h"
+#include "base/string_util.h"
+#include "base/utf_string_conversions.h"
+#include "content/common/gamepad_hardware_buffer.h"
+
+namespace content {
+
+using WebKit::WebGamepad;
+using WebKit::WebGamepads;
+
+GamepadPlatformDataFetcherLinux::GamepadPlatformDataFetcherLinux() {
+  for (size_t i = 0; i < arraysize(device_fds_); ++i)
+    device_fds_[i] = -1;
+
+  udev_ = udev_new();
+
+  monitor_ = udev_monitor_new_from_netlink(udev_, "udev");
+  udev_monitor_filter_add_match_subsystem_devtype(monitor_, "input", NULL);
+  udev_monitor_enable_receiving(monitor_);
+  monitor_fd_ = udev_monitor_get_fd(monitor_);
+  MessageLoopForIO::current()->WatchFileDescriptor(monitor_fd_, true,
+      MessageLoopForIO::WATCH_READ, &monitor_watcher_, this);
+
+  EnumerateDevices();
+}
+
+GamepadPlatformDataFetcherLinux::~GamepadPlatformDataFetcherLinux() {
+  monitor_watcher_.StopWatchingFileDescriptor();
+  udev_unref(udev_);
+  for (size_t i = 0; i < WebGamepads::itemsLengthCap; ++i) {
+    if (device_fds_[i] >= 0)
+      close(device_fds_[i]);
+  }
+}
+
+void GamepadPlatformDataFetcherLinux::GetGamepadData(WebGamepads* pads, bool) {
+  TRACE_EVENT0("GAMEPAD", "GetGamepadData");
+
+  data_.length = WebGamepads::itemsLengthCap;
+
+  // Update our internal state.
+  for (size_t i = 0; i < WebGamepads::itemsLengthCap; ++i) {
+    if (device_fds_[i] >= 0) {
+      ReadDeviceData(i);
+    }
+  }
+
+  // Copy to the current state to the output buffer, using the mapping
+  // function, if there is one available.
+  pads->length = data_.length;
+  for (size_t i = 0; i < WebGamepads::itemsLengthCap; ++i) {
+    if (mappers_[i])
+      mappers_[i](data_.items[i], &pads->items[i]);
+    else
+      pads->items[i] = data_.items[i];
+  }
+}
+
+void GamepadPlatformDataFetcherLinux::OnFileCanReadWithoutBlocking(int fd) {
+  // Events occur when devices attached to the system are added, removed, or
+  // change state. udev_monitor_receive_device() will return a device object
+  // representing the device which changed and what type of change occured.
+  DCHECK(monitor_fd_ == fd);
+  udev_device* dev = udev_monitor_receive_device(monitor_);
+  RefreshDevice(dev);
+  udev_device_unref(dev);
+}
+
+void GamepadPlatformDataFetcherLinux::OnFileCanWriteWithoutBlocking(int fd) {
+}
+
+bool GamepadPlatformDataFetcherLinux::IsGamepad(
+    udev_device* dev,
+    int& index,
+    std::string& path) {
+  if (!udev_device_get_property_value(dev, "ID_INPUT_JOYSTICK"))
+    return false;
+
+  const char* node_path = udev_device_get_devnode(dev);
+  if (!node_path)
+    return false;
+
+  static const char kJoystickRoot[] = "/dev/input/js";
+  bool is_gamepad =
+      strncmp(kJoystickRoot, node_path, sizeof(kJoystickRoot) - 1) == 0;
+  if (is_gamepad) {
+    const int base_len = sizeof(kJoystickRoot) - 1;
+    if (!base::StringToInt(base::StringPiece(
+            &node_path[base_len],
+            strlen(node_path) - base_len),
+        &index))
+      return false;
+    if (index < 0 || index >= static_cast<int>(WebGamepads::itemsLengthCap))
+      return false;
+    path = std::string(node_path);
+  }
+  return is_gamepad;
+}
+
+// Used during enumeration, and monitor notifications.
+void GamepadPlatformDataFetcherLinux::RefreshDevice(udev_device* dev) {
+  int index;
+  std::string node_path;
+  if (IsGamepad(dev, index, node_path)) {
+    int& device_fd = device_fds_[index];
+    WebGamepad& pad = data_.items[index];
+    GamepadStandardMappingFunction& mapper = mappers_[index];
+
+    if (device_fd >= 0)
+      close(device_fd);
+
+    // The device pointed to by dev contains information about the input
+    // device. In order to get the information about the USB device, get the
+    // parent device with the subsystem/devtype pair of "usb"/"usb_device".
+    // This function walks up the tree several levels.
+    dev = udev_device_get_parent_with_subsystem_devtype(
+        dev,
+        "usb",
+        "usb_device");
+    if (!dev) {
+      // Unable to get device information, don't use this device.
+      device_fd = -1;
+      pad.connected = false;
+      return;
+    }
+
+    device_fd = HANDLE_EINTR(open(node_path.c_str(), O_RDONLY | O_NONBLOCK));
+    if (device_fd < 0) {
+      // Unable to open device, don't use.
+      pad.connected = false;
+      return;
+    }
+
+    const char* vendor_id = udev_device_get_sysattr_value(dev, "idVendor");
+    const char* product_id = udev_device_get_sysattr_value(dev, "idProduct");
+    mapper = GetGamepadStandardMappingFunction(vendor_id, product_id);
+
+    const char* manufacturer =
+        udev_device_get_sysattr_value(dev, "manufacturer");
+    const char* product = udev_device_get_sysattr_value(dev, "product");
+
+    // Driver returns utf-8 strings here, so combine in utf-8 and then convert
+    // to WebUChar to build the id string.
+    std::string id;
+    if (mapper) {
+      id = base::StringPrintf("%s %s (STANDARD GAMEPAD)",
+          manufacturer,
+          product);
+    } else {
+      id = base::StringPrintf("%s %s (Vendor: %s Product: %s)",
+          manufacturer,
+          product,
+          vendor_id,
+          product_id);
+    }
+    TruncateUTF8ToByteSize(id, WebGamepad::idLengthCap - 1, &id);
+    string16 tmp16 = UTF8ToUTF16(id);
+    memset(pad.id, 0, sizeof(pad.id));
+    tmp16.copy(pad.id, arraysize(pad.id) - 1);
+
+    pad.connected = true;
+  }
+}
+
+void GamepadPlatformDataFetcherLinux::EnumerateDevices() {
+  udev_enumerate* enumerate = udev_enumerate_new(udev_);
+  udev_enumerate_add_match_subsystem(enumerate, "input");
+  udev_enumerate_scan_devices(enumerate);
+
+  udev_list_entry* devices = udev_enumerate_get_list_entry(enumerate);
+  for (udev_list_entry* dev_list_entry = devices;
+       dev_list_entry != NULL;
+       dev_list_entry = udev_list_entry_get_next(dev_list_entry)) {
+    // Get the filename of the /sys entry for the device and create a
+    // udev_device object (dev) representing it
+    const char* path = udev_list_entry_get_name(dev_list_entry);
+    udev_device* dev = udev_device_new_from_syspath(udev_, path);
+    RefreshDevice(dev);
+    udev_device_unref(dev);
+  }
+  // Free the enumerator object
+  udev_enumerate_unref(enumerate);
+}
+
+void GamepadPlatformDataFetcherLinux::ReadDeviceData(size_t index) {
+  int& fd = device_fds_[index];
+  WebGamepad& pad = data_.items[index];
+  DCHECK(fd >= 0);
+
+  js_event event;
+  while (HANDLE_EINTR(read(fd, &event, sizeof(struct js_event)) > 0)) {
+    size_t item = event.number;
+    if (event.type & JS_EVENT_AXIS) {
+      if (item >= WebGamepad::axesLengthCap)
+        continue;
+      pad.axes[item] = event.value / 32767.f;
+      if (item >= pad.axesLength)
+        pad.axesLength = item + 1;
+    } else if (event.type & JS_EVENT_BUTTON) {
+      if (item >= WebGamepad::buttonsLengthCap)
+        continue;
+      pad.buttons[item] = event.value ? 1.0 : 0.0;
+      if (item >= pad.buttonsLength)
+        pad.buttonsLength = item + 1;
+    }
+    pad.timestamp = event.time;
+  }
+}
+
+
+}  // namespace content
diff --git a/content/browser/gamepad/platform_data_fetcher_linux.h b/content/browser/gamepad/platform_data_fetcher_linux.h
new file mode 100644
index 0000000..3f395cf
--- /dev/null
+++ b/content/browser/gamepad/platform_data_fetcher_linux.h
@@ -0,0 +1,66 @@
+// Copyright (c) 2012 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.
+
+#ifndef CONTENT_BROWSER_GAMEPAD_DATA_FETCHER_LINUX_H_
+#define CONTENT_BROWSER_GAMEPAD_DATA_FETCHER_LINUX_H_
+
+#include <string>
+
+#include "base/compiler_specific.h"
+#include "base/message_pump_libevent.h"
+#include "build/build_config.h"
+#include "content/browser/gamepad/data_fetcher.h"
+#include "content/browser/gamepad/gamepad_standard_mappings_linux.h"
+#include "content/common/gamepad_hardware_buffer.h"
+
+extern "C" {
+struct udev;
+struct udev_device;
+struct udev_monitor;
+}
+
+namespace content {
+
+class GamepadPlatformDataFetcherLinux :
+    public GamepadDataFetcher,
+    public base::MessagePumpLibevent::Watcher {
+ public:
+  GamepadPlatformDataFetcherLinux();
+  virtual ~GamepadPlatformDataFetcherLinux();
+
+  // GamepadDataFetcher:
+  virtual void GetGamepadData(WebKit::WebGamepads* pads,
+                              bool devices_changed_hint) OVERRIDE;
+
+  // base::MessagePump:Libevent::Watcher:
+  virtual void OnFileCanReadWithoutBlocking(int fd) OVERRIDE;
+  virtual void OnFileCanWriteWithoutBlocking(int fd) OVERRIDE;
+
+ private:
+  bool IsGamepad(udev_device* dev, int& index, std::string& path);
+  void RefreshDevice(udev_device* dev);
+  void EnumerateDevices();
+  void ReadDeviceData(size_t index);
+
+  // libudev-related items, the main context, and the monitoring context to be
+  // notified about changes to device states.
+  udev* udev_;
+  udev_monitor* monitor_;
+  int monitor_fd_;
+  base::MessagePumpLibevent::FileDescriptorWatcher monitor_watcher_;
+
+  // File descriptors for the /dev/input/js* devices. -1 if not in use.
+  int device_fds_[WebKit::WebGamepads::itemsLengthCap];
+
+  // Functions to map from device data to standard layout, if available. May
+  // be null if no mapping is available.
+  GamepadStandardMappingFunction mappers_[WebKit::WebGamepads::itemsLengthCap];
+
+  // Data that's returned to the consumer.
+  WebKit::WebGamepads data_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_GAMEPAD_DATA_FETCHER_LINUX_H_
diff --git a/content/browser/gamepad/data_fetcher_mac.h b/content/browser/gamepad/platform_data_fetcher_mac.h
index 34f7d4b..360a183 100644
--- a/content/browser/gamepad/data_fetcher_mac.h
+++ b/content/browser/gamepad/platform_data_fetcher_mac.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 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.
 
@@ -23,10 +23,10 @@ class NSArray;
 
 namespace content {
 
-class GamepadDataFetcherMac : public GamepadDataFetcher {
+class GamepadPlatformDataFetcherMac : public GamepadDataFetcher {
  public:
-  GamepadDataFetcherMac();
-  virtual ~GamepadDataFetcherMac();
+  GamepadPlatformDataFetcherMac();
+  virtual ~GamepadPlatformDataFetcherMac();
   virtual void GetGamepadData(WebKit::WebGamepads* pads,
                               bool devices_changed_hint) OVERRIDE;
   virtual void PauseHint(bool paused) OVERRIDE;
@@ -34,7 +34,7 @@ class GamepadDataFetcherMac : public GamepadDataFetcher {
   bool enabled_;
   base::mac::ScopedCFTypeRef<IOHIDManagerRef> hid_manager_ref_;
 
-  static GamepadDataFetcherMac* InstanceFromContext(void* context);
+  static GamepadPlatformDataFetcherMac* InstanceFromContext(void* context);
   static void DeviceAddCallback(void* context,
                                 IOReturn result,
                                 void* sender,
diff --git a/content/browser/gamepad/data_fetcher_mac.mm b/content/browser/gamepad/platform_data_fetcher_mac.mm
index b06f01a..5e4ba8f 100644
--- a/content/browser/gamepad/data_fetcher_mac.mm
+++ b/content/browser/gamepad/platform_data_fetcher_mac.mm
@@ -1,8 +1,8 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 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 "content/browser/gamepad/data_fetcher_mac.h"
+#include "content/browser/gamepad/platform_data_fetcher_mac.h"
 
 #include "base/mac/foundation_util.h"
 #include "base/memory/scoped_nsobject.h"
@@ -41,7 +41,8 @@ const uint32_t kAxisMaximumUsageNumber = 0x35;
 
 }  // namespace
 
-GamepadDataFetcherMac::GamepadDataFetcherMac() : enabled_(true) {
+GamepadPlatformDataFetcherMac::GamepadPlatformDataFetcherMac()
+    : enabled_(true) {
   hid_manager_ref_.reset(IOHIDManagerCreate(kCFAllocatorDefault,
                                             kIOHIDOptionsTypeNone));
   if (CFGetTypeID(hid_manager_ref_) != IOHIDManagerGetTypeID()) {
@@ -61,7 +62,7 @@ GamepadDataFetcherMac::GamepadDataFetcherMac() : enabled_(true) {
   RegisterForNotifications();
 }
 
-void GamepadDataFetcherMac::RegisterForNotifications() {
+void GamepadPlatformDataFetcherMac::RegisterForNotifications() {
   // Register for plug/unplug notifications.
   IOHIDManagerRegisterDeviceMatchingCallback(
       hid_manager_ref_,
@@ -87,7 +88,7 @@ void GamepadDataFetcherMac::RegisterForNotifications() {
                               kIOHIDOptionsTypeSeizeDevice) == kIOReturnSuccess;
 }
 
-void GamepadDataFetcherMac::UnregisterFromNotifications() {
+void GamepadPlatformDataFetcherMac::UnregisterFromNotifications() {
   IOHIDManagerUnscheduleFromRunLoop(
       hid_manager_ref_,
       CFRunLoopGetCurrent(),
@@ -95,44 +96,45 @@ void GamepadDataFetcherMac::UnregisterFromNotifications() {
   IOHIDManagerClose(hid_manager_ref_, kIOHIDOptionsTypeNone);
 }
 
-void GamepadDataFetcherMac::PauseHint(bool pause) {
+void GamepadPlatformDataFetcherMac::PauseHint(bool pause) {
   if (pause)
     UnregisterFromNotifications();
   else
     RegisterForNotifications();
 }
 
-GamepadDataFetcherMac::~GamepadDataFetcherMac() {
+GamepadPlatformDataFetcherMac::~GamepadPlatformDataFetcherMac() {
   UnregisterFromNotifications();
 }
 
-GamepadDataFetcherMac* GamepadDataFetcherMac::InstanceFromContext(
+GamepadPlatformDataFetcherMac*
+GamepadPlatformDataFetcherMac::InstanceFromContext(
     void* context) {
-  return reinterpret_cast<GamepadDataFetcherMac*>(context);
+  return reinterpret_cast<GamepadPlatformDataFetcherMac*>(context);
 }
 
-void GamepadDataFetcherMac::DeviceAddCallback(void* context,
+void GamepadPlatformDataFetcherMac::DeviceAddCallback(void* context,
                                               IOReturn result,
                                               void* sender,
                                               IOHIDDeviceRef ref) {
   InstanceFromContext(context)->DeviceAdd(ref);
 }
 
-void GamepadDataFetcherMac::DeviceRemoveCallback(void* context,
+void GamepadPlatformDataFetcherMac::DeviceRemoveCallback(void* context,
                                                  IOReturn result,
                                                  void* sender,
                                                  IOHIDDeviceRef ref) {
   InstanceFromContext(context)->DeviceRemove(ref);
 }
 
-void GamepadDataFetcherMac::ValueChangedCallback(void* context,
+void GamepadPlatformDataFetcherMac::ValueChangedCallback(void* context,
                                                  IOReturn result,
                                                  void* sender,
                                                  IOHIDValueRef ref) {
   InstanceFromContext(context)->ValueChanged(ref);
 }
 
-void GamepadDataFetcherMac::AddButtonsAndAxes(NSArray* elements,
+void GamepadPlatformDataFetcherMac::AddButtonsAndAxes(NSArray* elements,
                                               size_t slot) {
   WebKit::WebGamepad& pad = data_.items[slot];
   AssociatedData& associated = associated_[slot];
@@ -168,7 +170,7 @@ void GamepadDataFetcherMac::AddButtonsAndAxes(NSArray* elements,
   }
 }
 
-void GamepadDataFetcherMac::DeviceAdd(IOHIDDeviceRef device) {
+void GamepadPlatformDataFetcherMac::DeviceAdd(IOHIDDeviceRef device) {
   using WebKit::WebGamepad;
   using WebKit::WebGamepads;
   using base::mac::CFToNSCast;
@@ -221,7 +223,7 @@ void GamepadDataFetcherMac::DeviceAdd(IOHIDDeviceRef device) {
     data_.length = slot + 1;
 }
 
-void GamepadDataFetcherMac::DeviceRemove(IOHIDDeviceRef device) {
+void GamepadPlatformDataFetcherMac::DeviceRemove(IOHIDDeviceRef device) {
   using WebKit::WebGamepads;
   size_t slot;
   if (!enabled_)
@@ -238,7 +240,7 @@ void GamepadDataFetcherMac::DeviceRemove(IOHIDDeviceRef device) {
   data_.items[slot].connected = false;
 }
 
-void GamepadDataFetcherMac::ValueChanged(IOHIDValueRef value) {
+void GamepadPlatformDataFetcherMac::ValueChanged(IOHIDValueRef value) {
   if (!enabled_)
     return;
 
@@ -276,7 +278,9 @@ void GamepadDataFetcherMac::ValueChanged(IOHIDValueRef value) {
   }
 }
 
-void GamepadDataFetcherMac::GetGamepadData(WebKit::WebGamepads* pads, bool) {
+void GamepadPlatformDataFetcherMac::GetGamepadData(
+    WebKit::WebGamepads* pads,
+    bool) {
   if (!enabled_) {
     pads->length = 0;
     return;
diff --git a/content/browser/gamepad/data_fetcher_win.cc b/content/browser/gamepad/platform_data_fetcher_win.cc
index 4cb874d..7f6f417 100644
--- a/content/browser/gamepad/data_fetcher_win.cc
+++ b/content/browser/gamepad/platform_data_fetcher_win.cc
@@ -1,8 +1,8 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 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 "content/browser/gamepad/data_fetcher_win.h"
+#include "content/browser/gamepad/platform_data_fetcher_win.h"
 
 #include "base/debug/trace_event.h"
 #include "content/common/gamepad_messages.h"
@@ -78,11 +78,11 @@ bool EnableXInput() {
 
 }
 
-GamepadDataFetcherWindows::GamepadDataFetcherWindows()
+GamepadPlatformDataFetcherWin::GamepadPlatformDataFetcherWin()
     : xinput_available_(EnableXInput()) {
 }
 
-void GamepadDataFetcherWindows::GetGamepadData(WebGamepads* pads,
+void GamepadPlatformDataFetcherWin::GetGamepadData(WebGamepads* pads,
                                         bool devices_changed_hint) {
   TRACE_EVENT0("GAMEPAD", "GetGamepadData");
 
@@ -113,7 +113,7 @@ void GamepadDataFetcherWindows::GetGamepadData(WebGamepads* pads,
         pad.connected = true;
         base::swprintf(pad.id,
                        WebGamepad::idLengthCap,
-                       L"Xbox 360 Controller (XInput %ls)",
+                       L"Xbox 360 Controller (XInput STANDARD %ls)",
                        GamepadSubTypeName(caps.SubType));
       }
     }
diff --git a/content/browser/gamepad/data_fetcher_win.h b/content/browser/gamepad/platform_data_fetcher_win.h
index 9193f67..1c91059 100644
--- a/content/browser/gamepad/data_fetcher_win.h
+++ b/content/browser/gamepad/platform_data_fetcher_win.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 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.
 
@@ -18,9 +18,9 @@
 
 namespace content {
 
-class GamepadDataFetcherWindows : public GamepadDataFetcher {
+class GamepadPlatformDataFetcherWin : public GamepadDataFetcher {
  public:
-  GamepadDataFetcherWindows();
+  GamepadPlatformDataFetcherWin();
   virtual void GetGamepadData(WebKit::WebGamepads* pads,
                               bool devices_changed_hint) OVERRIDE;
  private:
diff --git a/content/content_browser.gypi b/content/content_browser.gypi
index 69db33a..1a5089c 100644
--- a/content/content_browser.gypi
+++ b/content/content_browser.gypi
@@ -232,14 +232,19 @@
     'browser/font_list_async.cc',
     'browser/font_list_async.h',
     'browser/gamepad/data_fetcher.h',
-    'browser/gamepad/data_fetcher_mac.mm',
-    'browser/gamepad/data_fetcher_mac.h',
-    'browser/gamepad/data_fetcher_win.cc',
-    'browser/gamepad/data_fetcher_win.h',
     'browser/gamepad/gamepad_provider.cc',
     'browser/gamepad/gamepad_provider.h',
     'browser/gamepad/gamepad_service.cc',
     'browser/gamepad/gamepad_service.h',
+    'browser/gamepad/gamepad_standard_mappings_linux.cc',
+    'browser/gamepad/gamepad_standard_mappings_linux.h',
+    'browser/gamepad/platform_data_fetcher.h',
+    'browser/gamepad/platform_data_fetcher_linux.cc',
+    'browser/gamepad/platform_data_fetcher_linux.h',
+    'browser/gamepad/platform_data_fetcher_mac.h',
+    'browser/gamepad/platform_data_fetcher_mac.mm',
+    'browser/gamepad/platform_data_fetcher_win.cc',
+    'browser/gamepad/platform_data_fetcher_win.h',
     'browser/geolocation/arbitrator_dependency_factory.cc',
     'browser/geolocation/arbitrator_dependency_factory.h',
     'browser/geolocation/core_location_data_provider_mac.h',
@@ -706,6 +711,11 @@
         }],
       ],
     }],
+    ['OS=="linux"', {
+      'dependencies': [
+        '../build/linux/system.gyp:udev',
+      ],
+    }],
     ['OS=="linux" and toolkit_uses_gtk==0', {
       'dependencies': [
         '../build/linux/system.gyp:dbus',