device/gamepad/gamepad_device_linux.cc

// Copyright 2018 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 "device/gamepad/gamepad_device_linux.h"

#include <fcntl.h>
#include <limits.h>
#include <linux/input.h>
#include <linux/joystick.h>
#include <sys/ioctl.h>

#include "base/posix/eintr_wrapper.h"
#include "base/strings/stringprintf.h"
#include "device/udev_linux/udev_linux.h"

namespace device {

namespace {

const char kInputSubsystem[] = "input";
const char kUsbSubsystem[] = "usb";
const char kUsbDeviceType[] = "usb_device";
const float kMaxLinuxAxisValue = 32767.0;
const int kInvalidEffectId = -1;
const uint16_t kRumbleMagnitudeMax = 0xffff;

#define LONG_BITS (CHAR_BIT * sizeof(long))
#define BITS_TO_LONGS(x) (((x) + LONG_BITS - 1) / LONG_BITS)

static inline bool test_bit(int bit, const unsigned long* data) {
  return data[bit / LONG_BITS] & (1UL << (bit % LONG_BITS));
}

bool HasRumbleCapability(int fd) {
  unsigned long evbit[BITS_TO_LONGS(EV_MAX)];
  unsigned long ffbit[BITS_TO_LONGS(FF_MAX)];

  if (HANDLE_EINTR(ioctl(fd, EVIOCGBIT(0, EV_MAX), evbit)) < 0 ||
      HANDLE_EINTR(ioctl(fd, EVIOCGBIT(EV_FF, FF_MAX), ffbit)) < 0) {
    return false;
  }

  if (!test_bit(EV_FF, evbit)) {
    return false;
  }

  return test_bit(FF_RUMBLE, ffbit);
}

int StoreRumbleEffect(int fd,
                      int effect_id,
                      uint16_t duration,
                      uint16_t start_delay,
                      uint16_t strong_magnitude,
                      uint16_t weak_magnitude) {
  struct ff_effect effect;
  memset(&effect, 0, sizeof(effect));
  effect.type = FF_RUMBLE;
  effect.id = effect_id;
  effect.replay.length = duration;
  effect.replay.delay = start_delay;
  effect.u.rumble.strong_magnitude = strong_magnitude;
  effect.u.rumble.weak_magnitude = weak_magnitude;

  if (HANDLE_EINTR(ioctl(fd, EVIOCSFF, (const void*)&effect)) < 0)
    return kInvalidEffectId;
  return effect.id;
}

void DestroyEffect(int fd, int effect_id) {
  HANDLE_EINTR(ioctl(fd, EVIOCRMFF, effect_id));
}

bool StartOrStopEffect(int fd, int effect_id, bool do_start) {
  struct input_event start_stop;
  memset(&start_stop, 0, sizeof(start_stop));
  start_stop.type = EV_FF;
  start_stop.code = effect_id;
  start_stop.value = do_start ? 1 : 0;
  ssize_t nbytes =
      HANDLE_EINTR(write(fd, (const void*)&start_stop, sizeof(start_stop)));
  return nbytes == sizeof(start_stop);
}

}  // namespace

GamepadDeviceLinux::GamepadDeviceLinux(const std::string& parent_syspath)
    : parent_syspath_(parent_syspath),
      joydev_fd_(-1),
      joydev_index_(-1),
      evdev_fd_(-1),
      effect_id_(kInvalidEffectId),
      supports_vibration_(false) {}

GamepadDeviceLinux::~GamepadDeviceLinux() = default;

void GamepadDeviceLinux::DoShutdown() {
  CloseJoydevNode();
  CloseEvdevNode();
}

void GamepadDeviceLinux::ReadPadState(Gamepad* pad) const {
  DCHECK_GE(joydev_fd_, 0);

  js_event event;
  while (HANDLE_EINTR(read(joydev_fd_, &event, sizeof(struct js_event))) > 0) {
    size_t item = event.number;
    if (event.type & JS_EVENT_AXIS) {
      if (item >= Gamepad::kAxesLengthCap)
        continue;

      pad->axes[item] = event.value / kMaxLinuxAxisValue;

      if (item >= pad->axes_length)
        pad->axes_length = item + 1;
    } else if (event.type & JS_EVENT_BUTTON) {
      if (item >= Gamepad::kButtonsLengthCap)
        continue;

      pad->buttons[item].pressed = event.value;
      pad->buttons[item].value = event.value ? 1.0 : 0.0;

      if (item >= pad->buttons_length)
        pad->buttons_length = item + 1;
    }
    pad->timestamp = event.time;
  }
}

bool GamepadDeviceLinux::OpenJoydevNode(const std::string& path,
                                        udev_device* device,
                                        int joydev_index) {
  CloseJoydevNode();
  joydev_fd_ = open(path.c_str(), O_RDONLY | O_NONBLOCK);
  if (joydev_fd_ < 0)
    return false;

  udev_device* parent_device =
      device::udev_device_get_parent_with_subsystem_devtype(
          device, kInputSubsystem, nullptr);

  const char* vendor_id =
      udev_device_get_sysattr_value(parent_device, "id/vendor");
  const char* product_id =
      udev_device_get_sysattr_value(parent_device, "id/product");
  const char* version_number =
      udev_device_get_sysattr_value(parent_device, "id/version");
  const char* name = udev_device_get_sysattr_value(parent_device, "name");
  std::string name_string(name ? name : "");

  // In many cases the information the input subsystem contains isn't
  // as good as the information that the device bus has, walk up further
  // to the subsystem/device type "usb"/"usb_device" and if this device
  // has the same vendor/product id, prefer the description from that.
  struct udev_device* usb_device =
      udev_device_get_parent_with_subsystem_devtype(
          parent_device, kUsbSubsystem, kUsbDeviceType);
  if (usb_device) {
    const char* usb_vendor_id =
        udev_device_get_sysattr_value(usb_device, "idVendor");
    const char* usb_product_id =
        udev_device_get_sysattr_value(usb_device, "idProduct");

    if (vendor_id && product_id && strcmp(vendor_id, usb_vendor_id) == 0 &&
        strcmp(product_id, usb_product_id) == 0) {
      const char* manufacturer =
          udev_device_get_sysattr_value(usb_device, "manufacturer");
      const char* product =
          udev_device_get_sysattr_value(usb_device, "product");

      // Replace the previous name string with one containing the better
      // information.
      name_string = base::StringPrintf("%s %s", manufacturer, product);
    }
  }

  joydev_index_ = joydev_index;
  vendor_id_ = vendor_id ? vendor_id : "";
  product_id_ = product_id ? product_id : "";
  version_number_ = version_number ? version_number : "";
  name_ = name_string;
  return true;
}

void GamepadDeviceLinux::CloseJoydevNode() {
  if (joydev_fd_ >= 0) {
    close(joydev_fd_);
    joydev_fd_ = -1;
  }
  joydev_index_ = -1;
  vendor_id_.clear();
  product_id_.clear();
  version_number_.clear();
  name_.clear();
}

bool GamepadDeviceLinux::OpenEvdevNode(const std::string& path) {
  CloseEvdevNode();
  evdev_fd_ = open(path.c_str(), O_RDWR | O_NONBLOCK);
  if (evdev_fd_ < 0)
    return false;

  supports_vibration_ = HasRumbleCapability(evdev_fd_);

  return true;
}

void GamepadDeviceLinux::CloseEvdevNode() {
  if (evdev_fd_ >= 0) {
    if (effect_id_ != kInvalidEffectId)
      DestroyEffect(evdev_fd_, effect_id_);
    close(evdev_fd_);
    evdev_fd_ = -1;
  }
  supports_vibration_ = false;
}

void GamepadDeviceLinux::SetVibration(double strong_magnitude,
                                      double weak_magnitude) {
  uint16_t strong_magnitude_scaled =
      static_cast<uint16_t>(strong_magnitude * kRumbleMagnitudeMax);
  uint16_t weak_magnitude_scaled =
      static_cast<uint16_t>(weak_magnitude * kRumbleMagnitudeMax);

  // AbstractHapticGamepad will call SetZeroVibration when the effect is
  // complete, so we don't need to set the duration here except to make sure it
  // is at least as long as the maximum duration.
  uint16_t duration_millis =
      static_cast<uint16_t>(GamepadHapticActuator::kMaxEffectDurationMillis);

  // Upload the effect and get the new effect ID. If we already created an
  // effect on this device, reuse its ID.
  effect_id_ =
      StoreRumbleEffect(evdev_fd_, effect_id_, duration_millis, 0,
                        strong_magnitude_scaled, weak_magnitude_scaled);

  if (effect_id_ != kInvalidEffectId)
    StartOrStopEffect(evdev_fd_, effect_id_, true);
}

void GamepadDeviceLinux::SetZeroVibration() {
  if (effect_id_ != kInvalidEffectId)
    StartOrStopEffect(evdev_fd_, effect_id_, false);
}

}  // namespace device