Implement phosphor-buttons based C++ and sdbusplus interfaces.

This phosphor-buttons module handles all the physical buttons
like Reset/Power/ID button pressed/released signals and the
simulate signals on button pressed/released in WebUI.

All the signals are exposed into dbus and let other
modules be aware.

Change-Id: I52144718ef54d403c5221e5afd0216b9494f8523
Signed-off-by: Kuiying Wang <kuiying.wang@intel.com>
diff --git a/src/gpio.cpp b/src/gpio.cpp
new file mode 100644
index 0000000..72c569a
--- /dev/null
+++ b/src/gpio.cpp
@@ -0,0 +1,193 @@
+/*
+// Copyright (c) 2018 Intel Corporation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+*/
+
+#include <experimental/filesystem>
+#include <fcntl.h>
+#include <fstream>
+#include <phosphor-logging/elog-errors.hpp>
+#include <unistd.h>
+#include <xyz/openbmc_project/Common/error.hpp>
+#include "gpio.hpp"
+
+const static constexpr char* SYSMGR_SERVICE = "org.openbmc.managers.System";
+const static constexpr char* SYSMGR_OBJ_PATH = "/org/openbmc/managers/System";
+const static constexpr char* SYSMGR_INTERFACE = "org.openbmc.managers.System";
+
+void closeGpio(int fd)
+{
+    if (fd > 0)
+    {
+        ::close(fd);
+    }
+}
+
+int configGpio(const char* gpioName, int* fd, sdbusplus::bus::bus& bus)
+{
+    auto method = bus.new_method_call(SYSMGR_SERVICE, SYSMGR_OBJ_PATH,
+                                      SYSMGR_INTERFACE, "gpioInit");
+
+    method.append(gpioName);
+
+    auto result = bus.call(method);
+
+    if (result.is_method_error())
+    {
+        phosphor::logging::log<phosphor::logging::level::ERR>(
+            "bus call error!");
+        return -1;
+    }
+
+    int32_t gpioNum;
+    std::string gpioDev;
+    std::string gpioDirection;
+
+    result.read(gpioDev, gpioNum, gpioDirection);
+
+    std::string devPath;
+
+    std::fstream stream;
+
+    stream.exceptions(std::ifstream::failbit | std::ifstream::badbit);
+
+    devPath.clear();
+    devPath = gpioDev + "/gpio" + std::to_string(gpioNum) + "/value";
+
+    std::experimental::filesystem::path fullPath(devPath);
+
+    if (std::experimental::filesystem::exists(fullPath))
+    {
+        phosphor::logging::log<phosphor::logging::level::INFO>(
+            "GPIO exported",
+            phosphor::logging::entry("PATH=%s", devPath.c_str()));
+    }
+    else
+    {
+        devPath.clear();
+        devPath = gpioDev + "/export";
+
+        stream.open(devPath, std::fstream::out);
+        try
+        {
+            stream << gpioNum;
+            stream.close();
+        }
+
+        catch (const std::exception &e)
+        {
+            phosphor::logging::log<phosphor::logging::level::ERR>(
+                "Error in writing!",
+                phosphor::logging::entry("PATH=%s", devPath.c_str()),
+                phosphor::logging::entry("NUM=%d", gpioNum));
+            return -1;
+        }
+    }
+
+    if (gpioDirection == "out")
+    {
+        devPath.clear();
+        devPath = gpioDev + "/gpio" + std::to_string(gpioNum) + "/value";
+
+        uint32_t currentValue;
+
+        stream.open(devPath, std::fstream::in);
+        try
+        {
+            stream >> currentValue;
+            stream.close();
+        }
+
+        catch (const std::exception& e)
+        {
+            phosphor::logging::log<phosphor::logging::level::ERR>(
+                "Error in reading!",
+                phosphor::logging::entry("PATH=%s", devPath.c_str()));
+            return -1;
+        }
+
+        const char* direction = currentValue ? "high" : "low";
+
+        devPath.clear();
+        devPath = gpioDev + "/gpio" + std::to_string(gpioNum) + "/direction";
+
+        stream.open(devPath, std::fstream::out);
+        try
+        {
+            stream << direction;
+            stream.close();
+        }
+
+        catch (const std::exception& e)
+        {
+            phosphor::logging::log<phosphor::logging::level::ERR>(
+                "Error in writing!");
+            return -1;
+        }
+    }
+    else if (gpioDirection == "in")
+    {
+        devPath.clear();
+        devPath = gpioDev + "/gpio" + std::to_string(gpioNum) + "/direction";
+
+        stream.open(devPath, std::fstream::out);
+        try
+        {
+            stream << gpioDirection;
+            stream.close();
+        }
+
+        catch (const std::exception& e)
+        {
+            phosphor::logging::log<phosphor::logging::level::ERR>(
+                "Error in writing!");
+            return -1;
+        }
+    }
+    else if ((gpioDirection == "both"))
+    {
+
+        // For gpio configured as ‘both’, it is an interrupt pin and trigged on
+        // both rising and falling signals
+        devPath.clear();
+        devPath = gpioDev + "/gpio" + std::to_string(gpioNum) + "/edge";
+
+        stream.open(devPath, std::fstream::out);
+        try
+        {
+            stream << gpioDirection;
+            stream.close();
+        }
+
+        catch (const std::exception& e)
+        {
+            phosphor::logging::log<phosphor::logging::level::ERR>(
+                "Error in writing!");
+            return -1;
+        }
+    }
+
+    devPath.clear();
+    devPath = gpioDev + "/gpio" + std::to_string(gpioNum) + "/value";
+
+    *fd = ::open(devPath.c_str(), O_RDWR | O_NONBLOCK);
+
+    if (*fd < 0)
+    {
+        phosphor::logging::log<phosphor::logging::level::ERR>("open error!");
+        return -1;
+    }
+
+    return 0;
+}