1 files changed, 107 insertions, 0 deletions
diff --git a/presence/tach_sensor.hpp b/presence/tach_sensor.hpp
new file mode 100644
index 0000000..90d955b
--- /dev/null
+++ b/presence/tach_sensor.hpp
@@ -0,0 +1,107 @@
+#pragma once
+
+#include <sdbusplus/bus.hpp>
+#include <sdbusplus/server.hpp>
+#include "sensor_base.hpp"
+
+
+namespace phosphor
+{
+namespace fan
+{
+namespace presence
+{
+
+/**
+ * @class TachSensor
+ * @brief OpenBMC Tach feedback sensor presence implementation
+ * @details Derived sensor type that uses the tach feedback value to determine
+ * the presence of the fan enclosure that contains this sensor
+ */
+class TachSensor : public Sensor
+{
+    public:
+        TachSensor() = delete;
+        TachSensor(const TachSensor&) = delete;
+        TachSensor(TachSensor&&) = delete;
+        TachSensor& operator=(const TachSensor&) = delete;
+        TachSensor& operator=(TachSensor&&) = delete;
+        ~TachSensor() = default;
+
+        /**
+         * @brief Constructs Tach Sensor Object
+         *
+         * @param[in] bus - Dbus bus object
+         * @param[in] id - ID name of this sensor
+         * @param[in] fanEnc - Reference to the fan enclosure with this sensor
+         */
+        TachSensor(
+            sdbusplus::bus::bus& bus,
+            const std::string& id,
+            FanEnclosure& fanEnc) :
+                Sensor(id, fanEnc),
+                bus(bus),
+                tachSignal(bus,
+                           match(id).c_str(),
+                           handleTachChangeSignal,
+                           this)
+        {
+            // Nothing to do here
+        }
+
+        /**
+         * @brief Determine the presence of this sensor using the tach feedback
+         *
+         * @return Presence state based on tach feedback
+         */
+        bool isPresent();
+
+    private:
+        /** @brief Connection for sdbusplus bus */
+        sdbusplus::bus::bus& bus;
+        /** @brief Used to subscribe to dbus signals */
+        sdbusplus::server::match::match tachSignal;
+        /** @brief Tach speed value given from the signal */
+        int64_t tach = 0;
+
+        /**
+         * @brief Appends the fan sensor id to construct a match string
+         *
+         * @param[in] id - Fan sensor id
+         *
+         * @return Match string to register signal for the fan sensor id
+         */
+        static std::string match(const std::string& id)
+        {
+            return std::string("type='signal',"
+                               "interface='org.freedesktop.DBus.Properties',"
+                               "member='PropertiesChanged',"
+                               "path='/xyz/openbmc_project/sensors/fan_tach/" +
+                               id + "'");
+        }
+        /**
+         * @brief Callback function on tach change signals
+         *
+         * @param[out] msg - Data associated with the subscribed signal
+         * @param[out] data - Pointer to this tach sensor object instance
+         * @param[out] err - Contains any sdbus error reference if occurred
+         *
+         * @return 0
+         */
+        static int handleTachChangeSignal(sd_bus_message* msg,
+                                          void* data,
+                                          sd_bus_error* err);
+        /**
+         * @brief Determine & handle when the signal was a tach change
+         *
+         * @param[in] msg - Expanded sdbusplus message data
+         * @param[in] err - Contains any sdbus error reference if occurred
+         */
+        void handleTachChange(sdbusplus::message::message& msg,
+                              sd_bus_error* err);
+
+};
+
+} // namespace presence
+} // namespace fan
+} // namespace phosphor