presence: Add new tach sensor implementation

Add a new fan speed (tach) presence implementation for the new
PresenceSensor interface.

This fan tach sensor behaves mostly like the existing one, with
the addition of support for multiple tach sensors for the
single PresenceSensor instance, and implementation of the
PresenceSensor start and stop interfaces.

Change-Id: I535a3e2c78ef0f06f10b6f4cda9a7e2d0e9c11db
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>

3 files changed, 259 insertions, 0 deletions

diff --git a/presence/Makefile.am b/presence/Makefile.am
index e06a135..2ea4929 100644
--- a/presence/Makefile.am
+++ b/presence/Makefile.am
@@ -6,6 +6,7 @@ sbin_PROGRAMS = \
 
 phosphor_fan_presence_tach_SOURCES = \
 	fan.cpp \
+	tach.cpp \
 	fan_enclosure.cpp \
 	tach_sensor.cpp \
 	tach_detect.cpp
diff --git a/presence/tach.cpp b/presence/tach.cpp
new file mode 100644
index 0000000..deed040
--- /dev/null
+++ b/presence/tach.cpp
@@ -0,0 +1,148 @@
+/**
+ * Copyright © 2017 IBM 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 <string>
+#include <tuple>
+#include <vector>
+#include "tach.hpp"
+#include "rpolicy.hpp"
+
+namespace phosphor
+{
+namespace fan
+{
+namespace presence
+{
+
+using namespace std::literals::string_literals;
+
+static const auto tachNamespace = "/xyz/openbmc_project/sensors/fan_tach/"s;
+static const auto tachIface = "xyz.openbmc_project.Sensor.Value"s;
+static const auto tachProperty = "Value"s;
+
+Tach::Tach(
+        const std::vector<std::string>& sensors) : currentState(false)
+{
+    // Initialize state.
+    for (const auto& s : sensors)
+    {
+        state.emplace_back(s, nullptr, 0);
+    }
+}
+
+bool Tach::start()
+{
+    for (size_t i = 0; i < state.size(); ++i)
+    {
+        auto& s = state[i];
+        auto tachPath = tachNamespace + std::get<std::string>(s);
+
+        // Register for signal callbacks.
+        std::get<1>(s) = std::make_unique<sdbusplus::bus::match::match>(
+                util::SDBusPlus::getBus(),
+                sdbusplus::bus::match::rules::propertiesChanged(
+                    tachPath, tachIface),
+                [this, i](auto& msg){ this->propertiesChanged(i, msg);});
+
+        // Get an initial tach speed.
+        std::get<int64_t>(s) = util::SDBusPlus::getProperty<int64_t>(
+                tachPath,
+                tachIface,
+                tachProperty);
+    }
+
+    // Set the initial state of the sensor.
+    currentState = std::any_of(
+            state.begin(),
+            state.end(),
+            [](const auto & s)
+            {
+                return std::get<int64_t>(s) != 0;
+            });
+
+    return currentState;
+}
+
+void Tach::stop()
+{
+    for (auto& s : state)
+    {
+        // De-register signal callbacks.
+        std::get<1>(s) = nullptr;
+    }
+}
+
+bool Tach::present()
+{
+    // Live query the tach readings.
+    std::vector<int64_t> values;
+    for (const auto& s : state)
+    {
+        values.push_back(
+                util::SDBusPlus::getProperty<int64_t>(
+                        tachNamespace + std::get<std::string>(s),
+                        tachIface,
+                        tachProperty));
+    }
+
+    return std::any_of(
+            values.begin(),
+            values.end(),
+            [](const auto & v) {return v != 0;});
+}
+
+void Tach::propertiesChanged(
+        size_t sensor,
+        sdbusplus::message::message& msg)
+{
+    std::string iface;
+    util::Properties<int64_t> properties;
+    msg.read(iface, properties);
+
+    propertiesChanged(sensor, properties);
+}
+
+void Tach::propertiesChanged(
+        size_t sensor,
+        const util::Properties<int64_t>& props)
+{
+    auto& s = state[sensor];
+
+    // Find the Value property containing the speed.
+    auto it = props.find(tachProperty);
+    if (it != props.end())
+    {
+        std::get<int64_t>(s) =
+            sdbusplus::message::variant_ns::get<int64_t>(it->second);
+
+        auto newState = std::any_of(
+                state.begin(),
+                state.end(),
+                [](const auto & s)
+                {
+                    return std::get<int64_t>(s) != 0;
+                });
+
+        if (currentState != newState)
+        {
+            getPolicy().stateChanged(newState);
+            currentState = newState;
+        }
+    }
+}
+
+} // namespace presence
+} // namespace fan
+} // namespace phosphor
diff --git a/presence/tach.hpp b/presence/tach.hpp
new file mode 100644
index 0000000..4f02521
--- /dev/null
+++ b/presence/tach.hpp
@@ -0,0 +1,110 @@
+#pragma once
+
+#include <sdbusplus/message.hpp>
+#include <sdbusplus/bus/match.hpp>
+#include <string>
+#include <vector>
+#include "psensor.hpp"
+#include "sdbusplus.hpp"
+
+namespace phosphor
+{
+namespace fan
+{
+namespace presence
+{
+class RedundancyPolicy;
+
+/**
+ * @class Tach
+ * @brief Fan tach sensor presence implementation.
+ *
+ * The Tach class uses one or more tach speed indicators
+ * to determine presence state.
+ */
+class Tach : public PresenceSensor
+{
+    public:
+        /**
+         * @brief
+         *
+         * Cannot move or copy due to this ptr as context
+         * for sdbus callbacks.
+         */
+        Tach() = delete;
+        Tach(const Tach&) = delete;
+        Tach& operator=(const Tach&) = delete;
+        Tach(Tach&&) = delete;
+        Tach& operator=(Tach&&) = delete;
+        ~Tach() = default;
+
+        /**
+         * @brief ctor
+         *
+         * @param[in] sensors - Fan tach sensors for this psensor.
+         */
+        Tach(const std::vector<std::string>& sensors);
+
+        /**
+         * @brief start
+         *
+         * Register for dbus signal callbacks on fan
+         * tach sensor change.  Query initial tach speeds.
+         *
+         * @return The current sensor state.
+         */
+        bool start() override;
+
+        /**
+         * @brief stop
+         *
+         * De-register dbus signal callbacks.
+         */
+        void stop() override;
+
+        /**
+         * @brief Check the sensor.
+         *
+         * Query the tach speeds.
+         */
+        bool present() override;
+
+    private :
+        /**
+         * @brief Get the policy associated with this sensor.
+         */
+        virtual RedundancyPolicy& getPolicy() = 0;
+
+        /**
+         * @brief Properties changed handler for tach sensor updates.
+         *
+         * @param[in] sensor - The sensor that changed.
+         * @param[in] props - The properties that changed.
+         */
+        void propertiesChanged(
+            size_t sensor,
+            const phosphor::fan::util::Properties<int64_t>& props);
+
+        /**
+         * @brief Properties changed handler for tach sensor updates.
+         *
+         * @param[in] sensor - The sensor that changed.
+         * @param[in] msg - The sdbusplus signal message.
+         */
+        void propertiesChanged(
+            size_t sensor,
+            sdbusplus::message::message& msg);
+
+        /** @brief array of tach sensors dbus matches, and tach values. */
+        std::vector<std::tuple<
+            std::string,
+            std::unique_ptr<sdbusplus::bus::match::match>,
+            int64_t>> state;
+
+        /** The current state of the sensor. */
+        bool currentState;
+};
+
+} // namespace presence
+} // namespace fan
+} // namespace phosphor