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>

1 files changed, 148 insertions, 0 deletions

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