[dpdk-dev,v6,01/23] eventtimer: add event timer adapter API

diff --git a/lib/librte_eventdev/Makefile b/lib/librte_eventdev/Makefile
index 7fd78c7..685b474 100644
--- a/lib/librte_eventdev/Makefile
+++ b/lib/librte_eventdev/Makefile
@@ -27,6 +27,7 @@  SYMLINK-y-include += rte_eventdev_pmd_pci.h
 SYMLINK-y-include += rte_eventdev_pmd_vdev.h
 SYMLINK-y-include += rte_event_ring.h
 SYMLINK-y-include += rte_event_eth_rx_adapter.h
+SYMLINK-y-include += rte_event_timer_adapter.h
 
 # versioning export map
 EXPORT_MAP := rte_eventdev_version.map
diff --git a/lib/librte_eventdev/rte_event_timer_adapter.h b/lib/librte_eventdev/rte_event_timer_adapter.h
new file mode 100644
index 0000000..7d967e6
--- /dev/null
+++ b/lib/librte_eventdev/rte_event_timer_adapter.h
@@ -0,0 +1,566 @@ 
+/*-
+ *   BSD LICENSE
+ *
+ *   Copyright 2017 Cavium, Inc.
+ *   Copyright(c) 2017 Intel Corporation. All rights reserved.
+ *
+ *   Redistribution and use in source and binary forms, with or without
+ *   modification, are permitted provided that the following conditions
+ *   are met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in
+ *       the documentation and/or other materials provided with the
+ *       distribution.
+ *     * Neither the name of Intel Corporation nor the names of its
+ *       contributors may be used to endorse or promote products derived
+ *       from this software without specific prior written permission.
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#ifndef __RTE_EVENT_TIMER_ADAPTER_H__
+#define __RTE_EVENT_TIMER_ADAPTER_H__
+
+/**
+ * @file
+ *
+ * RTE Event Timer Adapter
+ *
+ * An event timer adapter has the following abstract working model:
+ *
+ *                               timer_tick_ns
+ *                                   +
+ *                      +-------+    |
+ *                      |       |    |
+ *              +-------+ bkt 0 +----v---+
+ *              |       |       |        |
+ *              |       +-------+        |
+ *          +---+---+                +---+---+  +---+---+---+---+
+ *          |       |                |       |  |   |   |   |   |
+ *          | bkt n |                | bkt 1 |<-> t0| t1| t2| tn|
+ *          |       |                |       |  |   |   |   |   |
+ *          +---+---+                +---+---+  +---+---+---+---+
+ *              |     Timer adapter      |
+ *          +---+---+                +---+---+
+ *          |       |                |       |
+ *          | bkt 4 |                | bkt 2 |<--- Current bucket
+ *          |       |                |       |
+ *          +---+---+                +---+---+
+ *               |      +-------+       |
+ *               |      |       |       |
+ *               +------+ bkt 3 +-------+
+ *                      |       |
+ *                      +-------+
+ *
+ * - It has a virtual monotonically increasing 64-bit timer adapter clock based
+ *   on *enum rte_event_timer_adapter_clk_src* clock source. The clock source
+ *   could be a CPU clock, or a platform depended external clock.
+ *
+ * - Application creates a timer adapter instance with given clock source,
+ *   the total number of event timers, resolution(expressed in ns) to traverse
+ *   between the buckets.
+ *
+ * - Each timer adapter may have 0 to n buckets based on the configured
+ *   max timeout(max_tmo_ns) and resolution(timer_tick_ns). On timer adapter
+ *   start, the timer starts ticking at *timer_tick_ns* resolution.
+ *
+ * - Application arms an event timer to be expired at the number of
+ *   *timer_tick_ns* from now.
+ *
+ * - Application can cancel the existing armed timer if required.
+ *
+ * - If not canceled by the application and the timer expires then the library
+ *   injects the timer expiry event to the designated event queue.
+ *
+ * - The timer expiry event will be received through *rte_event_dequeue_burst*
+ *
+ * - Application frees the created timer adapter instance.
+ *
+ * Multiple timer adapters can be created with a varying level of resolution
+ * for various expiry use cases that run in parallel.
+ *
+ * Before using the timer adapter, the application has to create and configure
+ * an event device along with the event ports. Based on the event device
+ * capability it might require creating an additional event port to be used
+ * by the timer adapter.
+ *
+ * The application creates the event timer adapter using the
+ * ``rte_event_timer_adapter_create()``. The event device id is passed to this
+ * function, inside this function the event device capability is checked,
+ * and if an in-built port is absent the application uses the default
+ * function to create a new producer port.
+ *
+ * The application may also use the function
+ * ``rte_event_timer_adapter_create_ext()`` to have granular control over
+ * producer port creation in a case where the in-built port is absent.
+ *
+ * After creating the timer adapter, the application has to start it
+ * using ``rte_event_timer_adapter_start()``. The buckets are traversed from
+ * 0 to n, the list per each bucket is processed, and the expired timer events
+ * are sent to the designated event queue.
+ *
+ * The application can arm one or more event timers using the
+ * ``rte_event_timer_arm_burst()``. The *timeout_ticks* represents the number
+ * of *timer_tick_ns* after which the timer has to expire. The timeout at
+ * which the timers expire can be grouped or be independent of each
+ * event timer instance. ``rte_event_timer_arm_tmo_tick_burst()`` address the
+ * former case and ``rte_event_timer_arm_burst()`` address the latter case.
+ *
+ * The application can cancel the timers from expiring using the
+ * ``rte_event_timer_cancel_burst()``.
+ *
+ * On the secondary process, ``rte_event_timer_adapter_lookup()`` can be used
+ * to get the timer adapter pointer from its id and use it to invoke fastpath
+ * operations such as arm and cancel.
+ *
+ * Some of the use cases of event timer adapter are Beacon Timers,
+ * Generic SW Timeout, Wireless MAC Scheduling, 3G Frame Protocols,
+ * Packet Scheduling, Protocol Retransmission Timers, Supervision Timers.
+ * All these use cases require high resolution and low time drift.
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <rte_spinlock.h>
+#include <rte_memory.h>
+
+#include "rte_eventdev.h"
+
+#define RTE_EVENT_TIMER_ADAPTER_NUM_MAX 64
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this enum may change without prior notice
+ *
+ * Timer adapter clock source
+ */
+enum rte_event_timer_adapter_clk_src {
+	RTE_EVENT_TIMER_ADAPTER_CPU_CLK,
+	/**< Use CPU clock as the clock source. */
+	RTE_EVENT_TIMER_ADAPTER_EXT_CLK0,
+	/**< Platform dependent external clock source 0. */
+	RTE_EVENT_TIMER_ADAPTER_EXT_CLK1,
+	/**< Platform dependent external clock source 1. */
+	RTE_EVENT_TIMER_ADAPTER_EXT_CLK2,
+	/**< Platform dependent external clock source 2. */
+	RTE_EVENT_TIMER_ADAPTER_EXT_CLK3,
+	/**< Platform dependent external clock source 3. */
+};
+
+#define RTE_EVENT_TIMER_ADAPTER_F_ADJUST_RES	(1ULL << 0)
+/**< The event timer adapter implementation may have constraints on the
+ * resolution (timer_tick_ns) and maximum timer expiry timeout(max_tmo_ns)
+ * based on the given timer adapter or system.  If this flag is set, the
+ * implementation adjusts the resolution and maximum timeout to the best
+ * possible configuration. On successful timer adapter creation, the
+ * application can get the configured resolution and max timeout with
+ * ``rte_event_timer_adapter_get_info()``.
+ */
+#define RTE_EVENT_TIMER_ADAPTER_F_SP_PUT	(1ULL << 1)
+/**< ``rte_event_timer_arm_burst()`` API to be used in single producer mode.
+ *
+ * @see struct rte_event_timer_adapter_conf::flags
+ */
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this structure may change without prior notice
+ *
+ * Timer adapter configuration structure
+ */
+struct rte_event_timer_adapter_conf {
+	uint8_t event_dev_id;
+	/**< Event device identifier */
+	uint16_t timer_adapter_id;
+	/**< Event timer adapter identifier */
+	uint32_t socket_id;
+	/**< Identifer of socket from which to allocate memory for adapter */
+	enum rte_event_timer_adapter_clk_src clk_src;
+	/**< Clock source for timer adapter */
+	uint64_t timer_tick_ns;
+	/**< Timer adapter resolution in ns */
+	uint64_t max_tmo_ns;
+	/**< Maximum timer timeout(expiry) in ns */
+	uint64_t nb_timers;
+	/**< Total number of timers per adapter */
+	uint64_t flags;
+	/**< Timer adapter config flags (RTE_EVENT_TIMER_ADAPTER_F_*) */
+};
+
+struct rte_event_timer_adapter;
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Callback function type for producer port creation.
+ */
+typedef int (*rte_event_timer_adapter_port_conf_cb_t)(uint16_t id,
+						      uint8_t event_dev_id,
+						      uint8_t *event_port_id,
+						      void *conf_arg);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Create an event timer adapter.
+ *
+ * This function must be invoked first before any other function in the API.
+ *
+ * @param conf
+ *   The event timer adapter configuration structure.
+ *
+ * @return
+ *   A pointer to the new allocated event timer adapter on success.
+ *   NULL on error with rte_errno set appropriately.
+ *   Possible rte_errno values include:
+ *   - ERANGE: timer_tick_ns is not in supported range.
+ */
+struct rte_event_timer_adapter *rte_event_timer_adapter_create(
+			const struct rte_event_timer_adapter_conf *conf);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Create a timer adapter with the supplied callback.
+ *
+ * This function can be used to have a more granular control over the timer
+ * adapter creation.  If a built-in port is absent, then the function uses the
+ * callback provided to create and get the port id to be used as a producer
+ * port.
+ *
+ * @param conf
+ *   The timer adapter configuration structure
+ * @param conf_cb
+ *   The port config callback function.
+ * @param conf_arg
+ *   Opaque pointer to the argument for the callback function
+ *
+ * @return
+ *   A pointer to the new allocated event timer adapter on success.
+ *   NULL on error with rte_errno set appropriately.
+ *   Possible rte_errno values include:
+ *   - ERANGE: timer_tick_ns is not in supported range.
+ *   - ENOMEM: unable to allocate sufficient memory for adapter instances
+ *   - EINVAL: invalid event device identifier specified in config
+ *   - ENOSPC: maximum number of adapters already created
+ */
+struct rte_event_timer_adapter *rte_event_timer_adapter_create_ext(
+			const struct rte_event_timer_adapter_conf *conf,
+			rte_event_timer_adapter_port_conf_cb_t conf_cb,
+			void *conf_arg);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this structure may change without prior notice
+ *
+ * Timer adapter info structure.
+ */
+struct rte_event_timer_adapter_info {
+	uint64_t min_resolution_ns;
+	/**< Minimum timer adapter resolution in ns */
+	uint64_t max_tmo_ns;
+	/**< Maximum timer timeout(expire) in ns */
+	struct rte_event_timer_adapter_conf conf;
+	/**< Configured timer adapter attributes */
+	uint32_t caps;
+	/**< Event timer adapter capabilities */
+	int16_t event_dev_port_id;
+	/**< Event device port ID, if applicable */
+	int32_t service_id;
+	/**< Service ID, if applicable */
+};
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Retrieve the contextual information of an event timer adapter.
+ *
+ * @param adapter
+ *   A pointer to the event timer adapter structure.
+ *
+ * @param[out] adapter_info
+ *   A pointer to a structure of type *rte_event_timer_adapter_info* to be
+ *   filled with the contextual information of the adapter.
+ *
+ * @return
+ *   - 0: Success, driver updates the contextual information of the
+ *   timer adapter
+ *   - <0: Error code returned by the driver info get function.
+ *   - -EINVAL if adapter identifier invalid
+ *
+ * @see RTE_EVENT_TIMER_ADAPTER_F_ADJUST_RES,
+ *   struct rte_event_timer_adapter_info
+ *
+ */
+int rte_event_timer_adapter_get_info(
+		const struct rte_event_timer_adapter *adapter,
+		struct rte_event_timer_adapter_info *adapter_info);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Start a timer adapter.
+ *
+ * The adapter start step is the last one and consists of setting the timer
+ * adapter to start accepting the timers and schedules to event queues.
+ *
+ * On success, all basic functions exported by the API (timer arm,
+ * timer cancel and so on) can be invoked.
+ *
+ * @param adapter
+ *   A pointer to the event timer adapter structure.
+ *
+ * @return
+ *   - 0: Success, adapter started.
+ *   - <0: Error code returned by the driver start function.
+ *   - -EINVAL if adapter identifier invalid
+ */
+int rte_event_timer_adapter_start(
+		const struct rte_event_timer_adapter *adapter);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Stop an event timer adapter.
+ *
+ * The adapter can be restarted with a call to
+ * ``rte_event_timer_adapter_start()``.
+ *
+ * @param adapter
+ *   A pointer to the event timer adapter structure.
+ *
+ * @return
+ *   - 0: Success, adapter stopped.
+ *   - <0: Error code returned by the driver stop function.
+ *   - -EINVAL if adapter identifier invalid
+ */
+int rte_event_timer_adapter_stop(const struct rte_event_timer_adapter *adapter);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Lookup an event timer adapter using its identifier.
+ *
+ * If an event timer adapter was created in another process with the same
+ * identifier, this function will locate its state and set up access to it
+ * so that it can be used in this process.
+ *
+ * @param adapter_id
+ *  The event timer adapter identifier.
+ *
+ * @return
+ *  A pointer to the event timer adapter matching the identifier on success.
+ *  NULL on error with rte_errno set appropriately.
+ *  Possible rte_errno values include:
+ *   - ENOENT - required entry not available to return.
+ */
+struct rte_event_timer_adapter *rte_event_timer_adapter_lookup(
+							uint16_t adapter_id);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Free an event timer adapter.
+ *
+ * Destroy an event timer adapter, freeing all resources.
+ *
+ * Before invoking this function, the application must wait for all the
+ * armed timers to expire or cancel the outstanding armed timers.
+ *
+ * @param adapter
+ *   A pointer to an event timer adapter structure.
+ *
+ * @return
+ *   - 0: Successfully freed the event timer adapter resources.
+ *   - <0: Failed to free the event timer adapter resources.
+ *   - -EAGAIN:  adapter is busy; timers outstanding
+ *   - -EBUSY: stop hasn't been called for this adapter yet
+ *   - -EINVAL: adapter id invalid, or adapter invalid
+ */
+int rte_event_timer_adapter_free(struct rte_event_timer_adapter *adapter);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this structure may change without prior notice
+ *
+ * Event timer state.
+ */
+enum rte_event_timer_state {
+	RTE_EVENT_TIMER_NOT_ARMED = 0,
+	/**< Event timer is in not armed state. */
+	RTE_EVENT_TIMER_ARMED = 1,
+	/**< Event timer successfully armed. */
+	RTE_EVENT_TIMER_CANCELED = 2,
+	/**< Event timer successfully canceled. */
+	RTE_EVENT_TIMER_ERROR = -1,
+	/**< Generic event timer error. */
+	RTE_EVENT_TIMER_ERROR_TOOEARLY = -2,
+	/**< Event timer timeout tick is too small to add to the adapter. */
+	RTE_EVENT_TIMER_ERROR_TOOLATE = -3,
+	/**< Event timer timeout tick is greater than the maximum timeout.*/
+};
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this structure may change without prior notice
+ *
+ * The generic *rte_event_timer* structure to hold the event timer attributes
+ * for arm and cancel operations.
+ */
+RTE_STD_C11
+struct rte_event_timer {
+	struct rte_event ev;
+	/**<
+	 * Expiry event attributes.  On successful event timer timeout,
+	 * the following attributes will be used to inject the expiry event to
+	 * the eventdev:
+	 *  - event_queue_id: Targeted event queue id for expiry events.
+	 *  - event_priority: Event priority of the event expiry event in the
+	 *  event queue relative to other events.
+	 *  - sched_type: Scheduling type of the expiry event.
+	 *  - flow_id: Flow id of the expiry event.
+	 *  - op: RTE_EVENT_OP_NEW
+	 *  - event_type: RTE_EVENT_TYPE_TIMER
+	 */
+	enum rte_event_timer_state state;
+	/**< State of the event timer. */
+	uint64_t timeout_ticks;
+	/**< Expiry timer ticks expressed in number of *timer_ticks_ns* from
+	 * now.
+	 * @see struct rte_event_timer_adapter_info::adapter_conf::timer_tick_ns
+	 */
+	uint64_t impl_opaque[2];
+	/**< Implementation-specific opaque data.
+	 * An event timer adapter implementation use this field to hold
+	 * implementation specific values to share between the arm and cancel
+	 * operations.  The application should not modify this field.
+	 */
+	uint8_t user_meta[];
+	/**< Memory to store user specific metadata.
+	 * The event timer adapter implementation should not modify this area.
+	 */
+} __rte_cache_aligned;
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Arm a burst of event timers with separate expiration timeout tick for each
+ * event timer.
+ *
+ * Before calling this function, the application allocates
+ * ``struct rte_event_timer`` objects from mempool or huge page backed
+ * application buffers of desired size. On successful allocation,
+ * application updates the `struct rte_event_timer`` attributes such as
+ * expiry event attributes, timeout ticks from now.
+ * This function submits the event timer arm requests to the event timer adapter
+ * and on expiry, the events will be injected to designated event queue.
+ *
+ * @param adapter
+ *   A pointer to an event timer adapter structure.
+ * @param evtims
+ *   Pointer to an array of objects of type *rte_event_timer* structure.
+ * @param nb_evtims
+ *   Number of event timers in the supplied array.
+ *
+ * @return
+ *   The number of successfully armed event timers. The return value can be less
+ *   than the value of the *nb_timers* parameter. If the return value is less
+ *   than *nb_events*, the remaining event timers at the end of *tim*
+ *   are not consumed, and the caller has to take care of them, and rte_errno
+ *   is set accordingly. Possible errno values include:
+ *   - -EINVAL  Invalid timer adapter identifier, expiry event queue ID is
+ *   invalid, or an expiry event's sched type doesn't match the capabilities of
+ *   the destination event queue.
+ *   - -EAGAIN Specified timer adapter is not running
+ */
+int rte_event_timer_arm_burst(const struct rte_event_timer_adapter *adapter,
+			      struct rte_event_timer **evtims,
+			      uint16_t nb_evtims);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Arm a burst of event timers with same expiration timeout tick.
+ *
+ * Provides the same functionality as ``rte_event_timer_arm_burst()``, except
+ * that application can use this API when all the event timers have the
+ * same timeout expiration tick. This specialized function can provide the
+ * additional hint to the adapter implementation and optimize if possible.
+ *
+ * @param adapter
+ *   A pointer to an event timer adapter structure.
+ * @param evtims
+ *   Points to an array of objects of type *rte_event_timer* structure.
+ * @param timeout_ticks
+ *   The number of ticks in which the timers should expire.
+ * @param nb_evtims
+ *   Number of event timers in the supplied array.
+ *
+ * @return
+ *   The number of successfully armed event timers. The return value can be less
+ *   than the value of the *nb_timers* parameter. If the return value is less
+ *   than *nb_events*, the remaining event timers at the end of *tim*
+ *   are not consumed, and the caller has to take care of them, and rte_errno
+ *   is set accordingly. Possible errno values include:
+ *   - -EINVAL  Invalid timer adapter identifier, expiry event queue ID is
+ *   invalid, or an expiry event's sched type doesn't match the capabilities of
+ *   the destination event queue.
+ *   - -EAGAIN Specified event timer adapter is not running
+ */
+int rte_event_timer_arm_tmo_tick_burst(
+			const struct rte_event_timer_adapter *adapter,
+			struct rte_event_timer **evtims,
+			const uint64_t timeout_ticks,
+			const uint16_t nb_evtims);
+
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice
+ *
+ * Cancel a burst of event timer from being scheduled to the event device.
+ *
+ * @param adapter
+ *   A pointer to an event timer adapter structure.
+ * @param event_timers
+ *   Points to an array of objects of type *rte_event_timer* structure
+ * @param nb_event_timers
+ *   Number of event timer instances in the supplied array.
+ *
+ * @return
+ *   The number of successfully canceled event timers. The return value can be
+ *   less than the value of the *nb_timers* parameter. If the return value is
+ *   less than *nb_events*, the remaining event timers at the end of *tim*
+ *   are not consumed, and the caller has to take care of them, and rte_errno
+ *   is set accordingly. Possible errno values include:
+ *   - -EINVAL  Invalid timer adapter identifier
+ *   - -EAGAIN  Specified timer adapter is not running
+ */
+int rte_event_timer_cancel_burst(const struct rte_event_timer_adapter *adapter,
+				 struct rte_event_timer **event_timers,
+				 uint16_t nb_event_timers);
+
+#endif /* __RTE_EVENT_TIMER_ADAPTER_H__ */
diff --git a/lib/librte_eventdev/rte_eventdev.h b/lib/librte_eventdev/rte_eventdev.h
index f1949ff..a650f7a 100644
--- a/lib/librte_eventdev/rte_eventdev.h
+++ b/lib/librte_eventdev/rte_eventdev.h
@@ -875,8 +875,8 @@  rte_event_dev_close(uint8_t dev_id);
 /**< The event generated from ethdev subsystem */
 #define RTE_EVENT_TYPE_CRYPTODEV        0x1
 /**< The event generated from crypodev subsystem */
-#define RTE_EVENT_TYPE_TIMERDEV         0x2
-/**< The event generated from timerdev subsystem */
+#define RTE_EVENT_TYPE_TIMER		0x2
+/**< The event generated from event timer adapter */
 #define RTE_EVENT_TYPE_CPU              0x3
 /**< The event generated from cpu for pipelining.
  * Application may use *sub_event_type* to further classify the event