dcmi : implement get temperature readings

This commit implements the plumbing around the 'Get Temperature
Readings' command. It doesn't read the temperatures from the relevant
sensors. That code is coming up in a subsequent commit.

Change-Id: I4514b65eb3ca65d52dd35185338a2c397e9a76ca
Signed-off-by: Deepak Kodihalli <dkodihal@in.ibm.com>

1 files changed, 82 insertions, 0 deletions

diff --git a/dcmihandler.hpp b/dcmihandler.hpp
index 288e4d7..a7cfe8a 100644
--- a/dcmihandler.hpp
+++ b/dcmihandler.hpp
@@ -20,6 +20,7 @@ enum Commands
     SET_ASSET_TAG = 0x08,
     GET_MGMNT_CTRL_ID_STR = 0x09,
     SET_MGMNT_CTRL_ID_STR = 0x0A,
+    GET_TEMP_READINGS = 0x10,
 };
 
 static constexpr auto propIntf = "org.freedesktop.DBus.Properties";
@@ -32,6 +33,7 @@ static constexpr auto networkConfigObj =
 static constexpr auto networkConfigIntf =
         "xyz.openbmc_project.Network.SystemConfiguration";
 static constexpr auto hostNameProp = "HostName";
+static constexpr auto temperatureSensorType = 0x01;
 
 namespace assettag
 {
@@ -43,6 +45,33 @@ namespace assettag
 
 } //namespace assettag
 
+namespace temp_readings
+{
+    static constexpr auto maxDataSets = 8;
+    static constexpr auto maxInstances = 255;
+    static constexpr auto maxTemp = 128; // degrees C
+
+    /** @struct Response
+     *
+     *  DCMI payload for Get Temperature Readings response
+     */
+    struct Response
+    {
+#if BYTE_ORDER == LITTLE_ENDIAN
+        uint8_t temperature: 7;   //!< Temperature reading in Celsius
+        uint8_t sign: 1;          //!< Sign bit
+#endif
+#if BYTE_ORDER == BIG_ENDIAN
+        uint8_t sign: 1;          //!< Sign bit
+        uint8_t temperature: 7;   //!< Temperature reading in Celsius
+#endif
+        uint8_t instance;       //!< Entity instance number
+    } __attribute__((packed));
+
+    using ResponseList = std::vector<Response>;
+    using NumInstances = size_t;
+}
+
 static constexpr auto groupExtId = 0xDC;
 
 static constexpr auto assetTagMaxOffset = 62;
@@ -320,6 +349,59 @@ struct DCMICapEntry
 
 using DCMICaps = std::map<DCMICapParameters, DCMICapEntry>;
 
+/** @struct GetTempReadingsRequest
+ *
+ *  DCMI payload for Get Temperature Readings request
+ */
+struct GetTempReadingsRequest
+{
+    uint8_t groupID;             //!< Group extension identification.
+    uint8_t sensorType;          //!< Type of the sensor
+    uint8_t entityId;            //!< Entity ID
+    uint8_t entityInstance;      //!< Entity Instance (0 means all instances)
+    uint8_t instanceStart;       //!< Instance start (used if instance is 0)
+} __attribute__((packed));
+
+/** @struct GetTempReadingsResponse
+ *
+ *  DCMI header for Get Temperature Readings response
+ */
+struct GetTempReadingsResponseHdr
+{
+    uint8_t groupID;                //!< Group extension identification.
+    uint8_t numInstances;           //!< No. of instances for requested id
+    uint8_t numDataSets;            //!< No. of sets of temperature data
+} __attribute__((packed));
+
+namespace temp_readings
+{
+    /** @brief Read temperatures and fill up DCMI response for the Get
+     *         Temperature Readings command. This looks at a specific
+     *         instance.
+     *
+     *  @param[in] type - one of "inlet", "cpu", "baseboard"
+     *  @param[in] instance - A non-zero Entity instance number
+     *
+     *  @return A tuple, containing a temperature reading and the
+     *          number of instances.
+     */
+    std::tuple<Response, NumInstances> read (const std::string& type,
+                                             uint8_t instance);
+
+    /** @brief Read temperatures and fill up DCMI response for the Get
+     *         Temperature Readings command. This looks at a range of
+     *         instances.
+     *
+     *  @param[in] type - one of "inlet", "cpu", "baseboard"
+     *  @param[in] instanceStart - Entity instance start index
+     *
+     *  @return A tuple, containing a list of temperature readings and the
+     *          number of instances.
+     */
+    std::tuple<ResponseList, NumInstances> readAll(const std::string& type,
+                                                   uint8_t instanceStart);
+}
+
 } // namespace dcmi
 
 #endif