src/platforms/common: move to platforms/common

Script to update include paths: for i in $(grep -rl 'include <px4_work_queue' src platforms); do sed -i 's/#include <px4_work_queue/#include <px4_platform_common\/px4_work_queue/' $i; done
2026-05-16 13:07:34 +08:00 · 2019-08-27 10:57:38 +02:00
parent 5d0e72040c
commit f8e0441e7b
124 changed files with 91 additions and 91 deletions
@@ -0,0 +1,57 @@
+############################################################################
+#
+#   Copyright (c) 2015 PX4 Development Team. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name PX4 nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+############################################################################
+
+# nuttx uses internal work queue currently
+if (NOT "${PX4_PLATFORM}" MATCHES "nuttx")
+
+	add_library(work_queue
+		dq_addlast.c
+		dq_rem.c
+		dq_remfirst.c
+		hrt_queue.c
+		hrt_thread.c
+		hrt_work_cancel.c
+		queue.c
+		sq_addafter.c
+		sq_addlast.c
+		sq_remfirst.c
+		work_cancel.c
+		work_lock.c
+		work_queue.c
+		work_thread.c
+	)
+	target_compile_definitions(work_queue PRIVATE MODULE_NAME="work_queue")
+	target_compile_options(work_queue PRIVATE -Wno-cast-align) # TODO: fix and enable
+	add_dependencies(work_queue prebuild_targets)
+
+endif()
@@ -0,0 +1,73 @@
+/************************************************************
+ * libc/queue/dq_addlast.c
+ *
+ *   Copyright (C) 2007, 2011 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name NuttX 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.
+ *
+ ************************************************************/
+
+/************************************************************
+ * Compilation Switches
+ ************************************************************/
+
+/************************************************************
+ * Included Files
+ ************************************************************/
+
+#include <stddef.h>
+#include <queue.h>
+
+/************************************************************
+ * Public Functions
+ ************************************************************/
+
+/************************************************************
+ * Name: dq_addlast
+ *
+ * Description
+ *   dq_addlast adds 'node' to the end of 'queue'
+ *
+ ************************************************************/
+
+void dq_addlast(dq_entry_t *node, dq_queue_t *queue)
+{
+	node->flink = NULL;
+	node->blink = queue->tail;
+
+	if (!queue->head) {
+		queue->head = node;
+		queue->tail = node;
+
+	} else {
+		queue->tail->flink = node;
+		queue->tail        = node;
+	}
+}
+
@@ -0,0 +1,81 @@
+/************************************************************
+ * libc/queue/dq_rem.c
+ *
+ *   Copyright (C) 2007, 2011 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name NuttX 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.
+ *
+ ************************************************************/
+
+/************************************************************
+ * Compilation Switches
+ ************************************************************/
+
+/************************************************************
+ * Included Files
+ ************************************************************/
+
+#include <stddef.h>
+#include <queue.h>
+
+/************************************************************
+ * Public Functions
+ ************************************************************/
+
+/************************************************************
+ * Name: dq_rem
+ *
+ * Description:
+ *   dq_rem removes 'node' from 'queue'
+ *
+ ************************************************************/
+
+void dq_rem(dq_entry_t *node, dq_queue_t *queue)
+{
+	dq_entry_t *prev = node->blink;
+	dq_entry_t *next = node->flink;
+
+	if (!prev) {
+		queue->head = next;
+
+	} else {
+		prev->flink = next;
+	}
+
+	if (!next) {
+		queue->tail = prev;
+
+	} else {
+		next->blink = prev;
+	}
+
+	node->flink = NULL;
+	node->blink = NULL;
+}
+
@@ -0,0 +1,81 @@
+/************************************************************
+ * libc/queue/dq_remfirst.c
+ *
+ *   Copyright (C) 2007, 2011 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name NuttX 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.
+ *
+ ************************************************************/
+
+/************************************************************
+ * Compilation Switches
+ ************************************************************/
+
+/************************************************************
+ * Included Files
+ ************************************************************/
+
+#include <stddef.h>
+#include <queue.h>
+
+/************************************************************
+ * Public Functions
+ ************************************************************/
+
+/************************************************************
+ * Name: dq_remfirst
+ *
+ * Description:
+ *   dq_remfirst removes 'node' from the head of 'queue'
+ *
+ ************************************************************/
+
+dq_entry_t *dq_remfirst(dq_queue_t *queue)
+{
+	dq_entry_t *ret = queue->head;
+
+	if (ret) {
+		dq_entry_t *next = ret->flink;
+
+		if (!next) {
+			queue->head = NULL;
+			queue->tail = NULL;
+
+		} else {
+			queue->head = next;
+			next->blink = NULL;
+		}
+
+		ret->flink = NULL;
+		ret->blink = NULL;
+	}
+
+	return ret;
+}
+
@@ -0,0 +1,140 @@
+/****************************************************************************
+ * libc/wqueue/work_queue.c
+ *
+ *   Copyright (C) 2009-2011, 2013 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name NuttX 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <px4_config.h>
+#include <px4_defines.h>
+#include <px4_workqueue.h>
+#include <px4_tasks.h>
+
+#include <signal.h>
+#include <stdint.h>
+#include <queue.h>
+#include <stdio.h>
+#include <semaphore.h>
+#include <drivers/drv_hrt.h>
+#include <px4_workqueue.h>
+#include <px4_posix.h>
+#include "hrt_work.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: hrt_work_queue
+ *
+ * Description:
+ *   Queue work to be performed at a later time.  All queued work will be
+ *   performed on the worker thread of of execution (not the caller's).
+ *
+ *   The work structure is allocated by caller, but completely managed by
+ *   the work queue logic.  The caller should never modify the contents of
+ *   the work queue structure; the caller should not call work_queue()
+ *   again until either (1) the previous work has been performed and removed
+ *   from the queue, or (2) work_cancel() has been called to cancel the work
+ *   and remove it from the work queue.
+ *
+ * Input parameters:
+ *   work   - The work structure to queue
+ *   worker - The worker callback to be invoked.  The callback will invoked
+ *            on the worker thread of execution.
+ *   arg    - The argument that will be passed to the workder callback when
+ *            int is invoked.
+ *   delay  - Delay (in microseconds) from the time queue until the worker
+ *            is invoked. Zero means to perform the work immediately.
+ *
+ * Returned Value:
+ *   Zero on success, a negated errno on failure
+ *
+ ****************************************************************************/
+
+int hrt_work_queue(struct work_s *work, worker_t worker, void *arg, uint32_t delay)
+{
+	struct wqueue_s *wqueue = &g_hrt_work;
+
+	/* First, initialize the work structure */
+
+	work->worker = worker;           /* Work callback */
+	work->arg    = arg;              /* Callback argument */
+	work->delay  = delay;            /* Delay until work performed */
+
+	/* Now, time-tag that entry and put it in the work queue.  This must be
+	 * done with interrupts disabled.  This permits this function to be called
+	 * from with task logic or interrupt handlers.
+	 */
+
+	hrt_work_lock();
+	work->qtime  = hrt_absolute_time(); /* Time work queued */
+	//PX4_INFO("hrt work_queue adding work delay=%u time=%lu", delay, work->qtime);
+
+	dq_addlast((dq_entry_t *)work, &wqueue->q);
+
+	if (px4_getpid() != wqueue->pid) { /* only need to wake up if called from a different thread */
+#ifdef __PX4_QURT
+		px4_task_kill(wqueue->pid, SIGALRM);      /* Wake up the worker thread */
+#else
+		//wqueue->pid == own task? -> don't signal
+		px4_task_kill(wqueue->pid, SIGCONT);      /* Wake up the worker thread */
+#endif
+	}
+
+	hrt_work_unlock();
+	return PX4_OK;
+}
+
@@ -0,0 +1,296 @@
+/****************************************************************************
+ * libc/wqueue/work_thread.c
+ *
+ *   Copyright (C) 2009-2013 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *   Modified by: Mark Charlebois to use hrt compatible times
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name NuttX 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <px4_config.h>
+#include <px4_defines.h>
+#include <px4_posix.h>
+#include <px4_tasks.h>
+#include <px4_time.h>
+#include <stdint.h>
+#include <signal.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <queue.h>
+#include <px4_workqueue.h>
+#include <drivers/drv_hrt.h>
+#include "hrt_work.h"
+
+#include <string.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/* The state of each work queue. */
+struct wqueue_s g_hrt_work;
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+px4_sem_t _hrt_work_lock;
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+static void hrt_work_process(void);
+
+static void _sighandler(int sig_num);
+
+/****************************************************************************
+ * Name: _sighandler
+ *
+ * Description:
+ *   This is the handler for the signal to wake the queue processing thread
+ *
+ * Input parameters:
+ *   sig_num - the received signal
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+static void _sighandler(int sig_num)
+{
+	PX4_DEBUG("RECEIVED SIGNAL %d", sig_num);
+}
+
+/****************************************************************************
+ * Name: work_process
+ *
+ * Description:
+ *   This is the logic that performs actions placed on any work list.
+ *
+ * Input parameters:
+ *   wqueue - Describes the work queue to be processed
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+static void hrt_work_process()
+{
+	struct wqueue_s *wqueue = &g_hrt_work;
+	volatile struct work_s *work;
+	worker_t  worker;
+	void *arg;
+	uint64_t elapsed;
+	uint32_t remaining;
+	uint32_t next;
+
+	// set the threads name
+#ifdef __PX4_DARWIN
+	pthread_setname_np("HRT");
+#else
+	// The Linux headers do not actually contain this
+	//rv = pthread_setname_np(pthread_self(), "HRT");
+#endif
+
+	/* Then process queued work.  We need to keep interrupts disabled while
+	 * we process items in the work list.
+	 */
+
+	/* Default to sleeping for 1 sec */
+	next  = 1000000;
+
+	hrt_work_lock();
+
+	work  = (struct work_s *)wqueue->q.head;
+
+	while (work) {
+		/* Is this work ready?  It is ready if there is no delay or if
+		 * the delay has elapsed. qtime is the time that the work was added
+		 * to the work queue.  It will always be greater than or equal to
+		 * zero.  Therefore a delay of zero will always execute immediately.
+		 */
+
+		elapsed = hrt_absolute_time() - work->qtime;
+
+		//PX4_INFO("hrt work_process: in usec elapsed=%lu delay=%u work=%p", elapsed, work->delay, work);
+		if (elapsed >= work->delay) {
+			/* Remove the ready-to-execute work from the list */
+
+			(void)dq_rem((struct dq_entry_s *) & (work->dq), &(wqueue->q));
+			//PX4_INFO("Dequeued work=%p", work);
+
+			/* Extract the work description from the entry (in case the work
+			 * instance by the re-used after it has been de-queued).
+			 */
+
+			worker = work->worker;
+			arg    = work->arg;
+
+			/* Mark the work as no longer being queued */
+
+			work->worker = NULL;
+
+			/* Do the work.  Re-enable interrupts while the work is being
+			 * performed... we don't have any idea how long that will take!
+			 */
+
+			hrt_work_unlock();
+
+			if (!worker) {
+				PX4_ERR("MESSED UP: worker = 0");
+
+			} else {
+				worker(arg);
+			}
+
+			/* Now, unfortunately, since we re-enabled interrupts we don't
+			 * know the state of the work list and we will have to start
+			 * back at the head of the list.
+			 */
+
+			hrt_work_lock();
+			work  = (struct work_s *)wqueue->q.head;
+
+		} else {
+			/* This one is not ready.. will it be ready before the next
+			 * scheduled wakeup interval?
+			 */
+
+			/* Here: elapsed < work->delay */
+			remaining = work->delay - elapsed;
+
+			//PX4_INFO("remaining=%u delay=%u elapsed=%lu", remaining, work->delay, elapsed);
+			if (remaining < next) {
+				/* Yes.. Then schedule to wake up when the work is ready */
+
+				next = remaining;
+			}
+
+			/* Then try the next in the list. */
+
+			work = (struct work_s *)work->dq.flink;
+			//PX4_INFO("next %u work %p", next, work);
+		}
+	}
+
+	/* Wait awhile to check the work list.  We will wait here until either
+	 * the time elapses or until we are awakened by a signal.
+	 */
+	hrt_work_unlock();
+
+	/* might sleep less if a signal received and new item was queued */
+	//PX4_INFO("Sleeping for %u usec", next);
+	px4_usleep(next);
+}
+
+/****************************************************************************
+ * Name: work_hrtthread
+ *
+ * Description:
+ *   This is the worker threads that performs actions placed on the ISR work
+ *   list.
+ *
+ *   work_hpthread and work_lpthread:  These are the kernel mode work queues
+ *     (also build in the flat build).  One of these threads also performs
+ *     periodic garbage collection (that is otherwise performed by the idle
+ *     thread if CONFIG_SCHED_WORKQUEUE is not defined).
+ *
+ *     These worker threads are started by the OS during normal bringup.
+ *
+ *   All of these entrypoints are referenced by OS internally and should not
+ *   not be accessed by application logic.
+ *
+ * Input parameters:
+ *   argc, argv (not used)
+ *
+ * Returned Value:
+ *   Does not return
+ *
+ ****************************************************************************/
+
+static int work_hrtthread(int argc, char *argv[])
+{
+	/* Loop forever */
+
+	for (;;) {
+		/* First, perform garbage collection.  This cleans-up memory de-allocations
+		 * that were queued because they could not be freed in that execution
+		 * context (for example, if the memory was freed from an interrupt handler).
+		 * NOTE: If the work thread is disabled, this clean-up is performed by
+		 * the IDLE thread (at a very, very low priority).
+		 */
+
+		/* Then process queued work.  We need to keep interrupts disabled while
+		 * we process items in the work list.
+		 */
+
+		hrt_work_process();
+	}
+
+	return PX4_OK; /* To keep some compilers happy */
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+void hrt_work_queue_init(void)
+{
+	px4_sem_init(&_hrt_work_lock, 0, 1);
+	memset(&g_hrt_work, 0, sizeof(g_hrt_work));
+
+	// Create high priority worker thread
+	g_hrt_work.pid = px4_task_spawn_cmd("wkr_hrt",
+					    SCHED_DEFAULT,
+					    SCHED_PRIORITY_MAX,
+					    2000,
+					    work_hrtthread,
+					    (char *const *)NULL);
+
+
+#ifdef __PX4_QURT
+	signal(SIGALRM, _sighandler);
+#else
+	signal(SIGCONT, _sighandler);
+#endif
+}
+
@@ -0,0 +1,111 @@
+/****************************************************************************
+ * libc/wqueue/work_cancel.c
+ *
+ *   Copyright (C) 2009-2010, 2012-2013 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name NuttX 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <px4_config.h>
+#include <px4_defines.h>
+#include <px4_workqueue.h>
+
+#include "hrt_work.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: hrt_work_cancel
+ *
+ * Description:
+ *   Cancel previously queued work.  This removes work from the work queue.
+ *   After work has been canceled, it may be re-queue by calling
+ *   hrt_work_queue() again.
+ *
+ * Input parameters:
+ *   work   - The previously queue work structure to cancel
+ *
+ ****************************************************************************/
+
+void hrt_work_cancel(struct work_s *work)
+{
+	struct wqueue_s *wqueue = &g_hrt_work;
+
+	//DEBUGASSERT(work != NULL && (unsigned)qid < NWORKERS);
+
+	/* Cancelling the work is simply a matter of removing the work structure
+	 * from the work queue.  This must be done with interrupts disabled because
+	 * new work is typically added to the work queue from interrupt handlers.
+	 */
+
+	hrt_work_lock();
+
+	if (work->worker != NULL) {
+		/* A little test of the integrity of the work queue */
+
+		//DEBUGASSERT(work->dq.flink ||(dq_entry_t *)work == wqueue->q.tail);
+		//DEBUGASSERT(work->dq.blink ||(dq_entry_t *)work == wqueue->q.head);
+
+		/* Remove the entry from the work queue and make sure that it is
+		 * mark as availalbe (i.e., the worker field is nullified).
+		 */
+
+		dq_rem((dq_entry_t *)work, &wqueue->q);
+		work->worker = NULL;
+	}
+
+	hrt_work_unlock();
+}
@@ -0,0 +1,98 @@
+/************************************************************************
+ *
+ *   Copyright (C) 2007-2009 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name NuttX 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.
+ *
+ * Modified for use in Linux by Mark Charlebois
+ *
+ ************************************************************************/
+
+// FIXME - need px4_queue
+#include <queue.h>
+#include <stddef.h>
+
+__EXPORT void sq_rem(sq_entry_t *node, sq_queue_t *queue);
+sq_entry_t *sq_remafter(sq_entry_t *node, sq_queue_t *queue);
+void sq_rem(sq_entry_t *node, sq_queue_t *queue)
+{
+	if (queue->head && node) {
+		if (node == queue->head) {
+			queue->head = node->flink;
+
+			if (node == queue->tail) {
+				queue->tail = NULL;
+			}
+
+		} else {
+			sq_entry_t *prev;
+
+			for (prev = (sq_entry_t *)queue->head;
+			     prev && prev->flink != node;
+			     prev = prev->flink);
+
+			if (prev) {
+				sq_remafter(prev, queue);
+			}
+		}
+	}
+}
+
+sq_entry_t *sq_remafter(sq_entry_t *node, sq_queue_t *queue)
+{
+	sq_entry_t *ret = node->flink;
+
+	if (queue->head && ret) {
+		if (queue->tail == ret) {
+			queue->tail = node;
+			node->flink = NULL;
+
+		} else {
+			node->flink = ret->flink;
+		}
+
+		ret->flink = NULL;
+	}
+
+	return ret;
+}
+
+__EXPORT void sq_addfirst(sq_entry_t *node, sq_queue_t *queue);
+void sq_addfirst(sq_entry_t *node, sq_queue_t *queue)
+{
+	node->flink = queue->head;
+
+	if (!queue->head) {
+		queue->tail = node;
+	}
+
+	queue->head = node;
+}
+
+
@@ -0,0 +1,69 @@
+/************************************************************
+ * libc/queue/sq_addafter.c
+ *
+ *   Copyright (C) 2007, 2011 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name NuttX 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.
+ *
+ ************************************************************/
+
+/************************************************************
+ * Compilation Switches
+ ************************************************************/
+
+/************************************************************
+ * Included Files
+ ************************************************************/
+
+#include <queue.h>
+
+/************************************************************
+ * Public Functions
+ ************************************************************/
+
+/************************************************************
+ * Name: sq_addafter.c
+ *
+ * Description:
+ *  The sq_addafter function adds 'node' after 'prev' in the
+ *  'queue.'
+ *
+ ************************************************************/
+
+void sq_addafter(sq_entry_t *prev, sq_entry_t *node,
+		 sq_queue_t *queue)
+{
+	if (!queue->head || prev == queue->tail) {
+		sq_addlast(node, queue);
+
+	} else {
+		node->flink = prev->flink;
+		prev->flink = node;
+	}
+}
@@ -0,0 +1,72 @@
+/************************************************************
+ * libc/queue/sq_addlast.c
+ *
+ *   Copyright (C) 2007, 2011 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name NuttX 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.
+ *
+ ************************************************************/
+
+/************************************************************
+ * Compilation Switches
+ ************************************************************/
+
+/************************************************************
+ * Included Files
+ ************************************************************/
+
+#include <stddef.h>
+#include <queue.h>
+
+/************************************************************
+ * Public Functions
+ ************************************************************/
+
+/************************************************************
+ * Name: sq_addlast
+ *
+ * Description:
+ *   The sq_addlast function places the 'node' at the tail of
+ *   the 'queue'
+ ************************************************************/
+
+void sq_addlast(sq_entry_t *node, sq_queue_t *queue)
+{
+	node->flink = NULL;
+
+	if (!queue->head) {
+		queue->head = node;
+		queue->tail = node;
+
+	} else {
+		queue->tail->flink = node;
+		queue->tail        = node;
+	}
+}
+
@@ -0,0 +1,76 @@
+/************************************************************
+ * libc/queue/sq_remfirst.c
+ *
+ *   Copyright (C) 2007, 2011 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name NuttX 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.
+ *
+ ************************************************************/
+
+/************************************************************
+ * Compilation Switches
+ ************************************************************/
+
+/************************************************************
+ * Included Files
+ ************************************************************/
+
+#include <stddef.h>
+#include <queue.h>
+
+/************************************************************
+ * Public Functions
+ ************************************************************/
+
+/************************************************************
+ * Name: sq_remfirst
+ *
+ * Description:
+ *   sq_remfirst function removes the first entry from
+ *   'queue'
+ *
+ ************************************************************/
+
+sq_entry_t *sq_remfirst(sq_queue_t *queue)
+{
+	sq_entry_t *ret = queue->head;
+
+	if (ret) {
+		queue->head = ret->flink;
+
+		if (!queue->head) {
+			queue->tail = NULL;
+		}
+
+		ret->flink = NULL;
+	}
+
+	return ret;
+}
+
@@ -0,0 +1,120 @@
+/****************************************************************************
+ * libc/wqueue/work_cancel.c
+ *
+ *   Copyright (C) 2009-2010, 2012-2013 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name NuttX 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <px4_config.h>
+#include <px4_defines.h>
+#include <queue.h>
+#include <px4_workqueue.h>
+#include "work_lock.h"
+
+#ifdef CONFIG_SCHED_WORKQUEUE
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: work_cancel
+ *
+ * Description:
+ *   Cancel previously queued work.  This removes work from the work queue.
+ *   After work has been canceled, it may be re-queue by calling work_queue()
+ *   again.
+ *
+ * Input parameters:
+ *   qid    - The work queue ID
+ *   work   - The previously queue work structure to cancel
+ *
+ * Returned Value:
+ *   Zero on success, a negated errno on failure
+ *
+ ****************************************************************************/
+
+int work_cancel(int qid, struct work_s *work)
+{
+	struct wqueue_s *wqueue = &g_work[qid];
+
+	//DEBUGASSERT(work != NULL && (unsigned)qid < NWORKERS);
+
+	/* Cancelling the work is simply a matter of removing the work structure
+	 * from the work queue.  This must be done with interrupts disabled because
+	 * new work is typically added to the work queue from interrupt handlers.
+	 */
+
+	work_lock(qid);
+
+	if (work->worker != NULL) {
+		/* A little test of the integrity of the work queue */
+
+		//DEBUGASSERT(work->dq.flink ||(dq_entry_t *)work == wqueue->q.tail);
+		//DEBUGASSERT(work->dq.blink ||(dq_entry_t *)work == wqueue->q.head);
+
+		/* Remove the entry from the work queue and make sure that it is
+		 * mark as availalbe (i.e., the worker field is nullified).
+		 */
+
+		dq_rem((dq_entry_t *)work, &wqueue->q);
+		work->worker = NULL;
+	}
+
+	work_unlock(qid);
+	return PX4_OK;
+}
+
+#endif /* CONFIG_SCHED_WORKQUEUE */
@@ -0,0 +1,49 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2015 Mark Charlebois. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name PX4 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.
+ *
+ ****************************************************************************/
+#include <px4_log.h>
+#include <px4_posix.h>
+#include <stdio.h>
+#include "work_lock.h"
+
+
+extern px4_sem_t _work_lock[];
+
+void work_lock(int id)
+{
+	px4_sem_wait(&_work_lock[id]);
+}
+
+void work_unlock(int id)
+{
+	px4_sem_post(&_work_lock[id]);
+}
@@ -0,0 +1,43 @@
+/****************************************************************************
+ *
+ * Copyright (C) 2015 Mark Charlebois. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name PX4 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 _work_lock_h_
+#define _work_lock_h_
+
+
+//#pragma once
+
+void work_lock(int id);
+void work_unlock(int id);
+
+#endif // _work_lock_h_
@@ -0,0 +1,138 @@
+/****************************************************************************
+ * libc/wqueue/work_queue.c
+ *
+ *   Copyright (C) 2009-2011, 2013 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name NuttX 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <px4_config.h>
+#include <px4_defines.h>
+#include <px4_workqueue.h>
+#include <px4_tasks.h>
+
+#include <signal.h>
+#include <stdint.h>
+#include <queue.h>
+#include <stdio.h>
+#include <semaphore.h>
+#include "work_lock.h"
+
+#ifdef CONFIG_SCHED_WORKQUEUE
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: work_queue
+ *
+ * Description:
+ *   Queue work to be performed at a later time.  All queued work will be
+ *   performed on the worker thread of of execution (not the caller's).
+ *
+ *   The work structure is allocated by caller, but completely managed by
+ *   the work queue logic.  The caller should never modify the contents of
+ *   the work queue structure; the caller should not call work_queue()
+ *   again until either (1) the previous work has been performed and removed
+ *   from the queue, or (2) work_cancel() has been called to cancel the work
+ *   and remove it from the work queue.
+ *
+ * Input parameters:
+ *   qid    - The work queue ID (index)
+ *   work   - The work structure to queue
+ *   worker - The worker callback to be invoked.  The callback will invoked
+ *            on the worker thread of execution.
+ *   arg    - The argument that will be passed to the workder callback when
+ *            int is invoked.
+ *   delay  - Delay (in clock ticks) from the time queue until the worker
+ *            is invoked. Zero means to perform the work immediately.
+ *
+ * Returned Value:
+ *   Zero on success, a negated errno on failure
+ *
+ ****************************************************************************/
+
+int work_queue(int qid, struct work_s *work, worker_t worker, void *arg, uint32_t delay)
+{
+	struct wqueue_s *wqueue = &g_work[qid];
+
+	//DEBUGASSERT(work != NULL && (unsigned)qid < NWORKERS);
+
+	/* First, initialize the work structure */
+
+	work->worker = worker;           /* Work callback */
+	work->arg    = arg;              /* Callback argument */
+	work->delay  = delay;            /* Delay until work performed */
+
+	/* Now, time-tag that entry and put it in the work queue.  This must be
+	 * done with interrupts disabled.  This permits this function to be called
+	 * from with task logic or interrupt handlers.
+	 */
+
+	work_lock(qid);
+	work->qtime  = clock_systimer(); /* Time work queued */
+
+	dq_addlast((dq_entry_t *)work, &wqueue->q);
+#ifdef __PX4_QURT
+	px4_task_kill(wqueue->pid, SIGALRM);      /* Wake up the worker thread */
+#else
+	px4_task_kill(wqueue->pid, SIGCONT);      /* Wake up the worker thread */
+#endif
+
+	work_unlock(qid);
+	return PX4_OK;
+}
+
+#endif /* CONFIG_SCHED_WORKQUEUE */
@@ -0,0 +1,337 @@
+/****************************************************************************
+ * libc/wqueue/work_thread.c
+ *
+ *   Copyright (C) 2009-2013 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name NuttX 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <px4_config.h>
+#include <px4_defines.h>
+#include <px4_posix.h>
+#include <px4_time.h>
+#include <px4_tasks.h>
+#include <px4_workqueue.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <queue.h>
+#include <pthread.h>
+#include <drivers/drv_hrt.h>
+#include "work_lock.h"
+
+#ifdef CONFIG_SCHED_WORKQUEUE
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/* The state of each work queue. */
+struct wqueue_s g_work[NWORKERS];
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+px4_sem_t _work_lock[NWORKERS];
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: work_process
+ *
+ * Description:
+ *   This is the logic that performs actions placed on any work list.
+ *
+ * Input parameters:
+ *   wqueue - Describes the work queue to be processed
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+static void work_process(struct wqueue_s *wqueue, int lock_id)
+{
+	volatile struct work_s *work;
+	worker_t  worker;
+	void *arg;
+	uint64_t elapsed;
+	uint32_t remaining;
+	uint32_t next;
+
+	/* Then process queued work.  We need to keep interrupts disabled while
+	 * we process items in the work list.
+	 */
+
+	next  = CONFIG_SCHED_WORKPERIOD;
+
+	work_lock(lock_id);
+
+	work  = (struct work_s *)wqueue->q.head;
+
+	while (work) {
+		/* Is this work ready?  It is ready if there is no delay or if
+		 * the delay has elapsed. qtime is the time that the work was added
+		 * to the work queue.  It will always be greater than or equal to
+		 * zero.  Therefore a delay of zero will always execute immediately.
+		 */
+
+		elapsed = USEC2TICK(clock_systimer() - work->qtime);
+
+		//printf("work_process: in ticks elapsed=%lu delay=%u\n", elapsed, work->delay);
+		if (elapsed >= work->delay) {
+			/* Remove the ready-to-execute work from the list */
+
+			(void)dq_rem((struct dq_entry_s *)work, &wqueue->q);
+
+			/* Extract the work description from the entry (in case the work
+			 * instance by the re-used after it has been de-queued).
+			 */
+
+			worker = work->worker;
+			arg    = work->arg;
+
+			/* Mark the work as no longer being queued */
+
+			work->worker = NULL;
+
+			/* Do the work.  Re-enable interrupts while the work is being
+			 * performed... we don't have any idea how long that will take!
+			 */
+
+			work_unlock(lock_id);
+
+			if (!worker) {
+				PX4_WARN("MESSED UP: worker = 0\n");
+
+			} else {
+				worker(arg);
+			}
+
+			/* Now, unfortunately, since we re-enabled interrupts we don't
+			 * know the state of the work list and we will have to start
+			 * back at the head of the list.
+			 */
+
+			work_lock(lock_id);
+			work  = (struct work_s *)wqueue->q.head;
+
+		} else {
+			/* This one is not ready.. will it be ready before the next
+			 * scheduled wakeup interval?
+			 */
+
+			/* Here: elapsed < work->delay */
+			remaining = USEC_PER_TICK * (work->delay - elapsed);
+
+			if (remaining < next) {
+				/* Yes.. Then schedule to wake up when the work is ready */
+
+				next = remaining;
+			}
+
+			/* Then try the next in the list. */
+
+			work = (struct work_s *)work->dq.flink;
+		}
+	}
+
+	/* Wait awhile to check the work list.  We will wait here until either
+	 * the time elapses or until we are awakened by a signal.
+	 */
+	work_unlock(lock_id);
+
+	px4_usleep(next);
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+void work_queues_init(void)
+{
+	px4_sem_init(&_work_lock[HPWORK], 0, 1);
+	px4_sem_init(&_work_lock[LPWORK], 0, 1);
+#ifdef CONFIG_SCHED_USRWORK
+	px4_sem_init(&_work_lock[USRWORK], 0, 1);
+#endif
+
+	// Create high priority worker thread
+	g_work[HPWORK].pid = px4_task_spawn_cmd("hpwork",
+						SCHED_DEFAULT,
+						SCHED_PRIORITY_MAX - 1,
+						2000,
+						work_hpthread,
+						(char *const *)NULL);
+
+	// Create low priority worker thread
+	g_work[LPWORK].pid = px4_task_spawn_cmd("lpwork",
+						SCHED_DEFAULT,
+						SCHED_PRIORITY_MIN,
+						2000,
+						work_lpthread,
+						(char *const *)NULL);
+
+}
+
+/****************************************************************************
+ * Name: work_hpthread, work_lpthread, and work_usrthread
+ *
+ * Description:
+ *   These are the worker threads that performs actions placed on the work
+ *   lists.
+ *
+ *   work_hpthread and work_lpthread:  These are the kernel mode work queues
+ *     (also build in the flat build).  One of these threads also performs
+ *     periodic garbage collection (that is otherwise performed by the idle
+ *     thread if CONFIG_SCHED_WORKQUEUE is not defined).
+ *
+ *     These worker threads are started by the OS during normal bringup.
+ *
+ *   work_usrthread:  This is a user mode work queue.  It must be built into
+ *     the applicatino blob during the user phase of a kernel build.  The
+ *     user work thread will then automatically be started when the system
+ *     boots by calling through the pointer found in the header on the user
+ *     space blob.
+ *
+ *   All of these entrypoints are referenced by OS internally and should not
+ *   not be accessed by application logic.
+ *
+ * Input parameters:
+ *   argc, argv (not used)
+ *
+ * Returned Value:
+ *   Does not return
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_SCHED_HPWORK
+
+int work_hpthread(int argc, char *argv[])
+{
+	/* Loop forever */
+
+	for (;;) {
+		/* First, perform garbage collection.  This cleans-up memory de-allocations
+		 * that were queued because they could not be freed in that execution
+		 * context (for example, if the memory was freed from an interrupt handler).
+		 * NOTE: If the work thread is disabled, this clean-up is performed by
+		 * the IDLE thread (at a very, very low priority).
+		 */
+
+#ifndef CONFIG_SCHED_LPWORK
+		sched_garbagecollection();
+#endif
+
+		/* Then process queued work.  We need to keep interrupts disabled while
+		 * we process items in the work list.
+		 */
+
+		work_process(&g_work[HPWORK], HPWORK);
+	}
+
+	return PX4_OK; /* To keep some compilers happy */
+}
+
+#ifdef CONFIG_SCHED_LPWORK
+
+int work_lpthread(int argc, char *argv[])
+{
+	/* Loop forever */
+
+	for (;;) {
+		/* First, perform garbage collection.  This cleans-up memory de-allocations
+		 * that were queued because they could not be freed in that execution
+		 * context (for example, if the memory was freed from an interrupt handler).
+		 * NOTE: If the work thread is disabled, this clean-up is performed by
+		 * the IDLE thread (at a very, very low priority).
+		 */
+
+		//sched_garbagecollection();
+
+		/* Then process queued work.  We need to keep interrupts disabled while
+		 * we process items in the work list.
+		 */
+
+		work_process(&g_work[LPWORK], LPWORK);
+	}
+
+	return PX4_OK; /* To keep some compilers happy */
+}
+
+#endif /* CONFIG_SCHED_LPWORK */
+#endif /* CONFIG_SCHED_HPWORK */
+
+#ifdef CONFIG_SCHED_USRWORK
+
+int work_usrthread(int argc, char *argv[])
+{
+	/* Loop forever */
+
+	int rv;
+	// set the threads name
+#ifdef __PX4_DARWIN
+	rv = pthread_setname_np("USR");
+#else
+	rv = pthread_setname_np(pthread_self(), "USR");
+#endif
+
+	for (;;) {
+		/* Then process queued work.  We need to keep interrupts disabled while
+		 * we process items in the work list.
+		 */
+
+		work_process(&g_work[USRWORK], USRWORK);
+	}
+
+	return PX4_OK; /* To keep some compilers happy */
+}
+
+#endif /* CONFIG_SCHED_USRWORK */
+
+uint32_t clock_systimer()
+{
+	//printf("clock_systimer: %0lx\n", hrt_absolute_time());
+	return (0x00000000ffffffff & hrt_absolute_time());
+}
+#endif /* CONFIG_SCHED_WORKQUEUE */
@@ -0,0 +1,41 @@
+############################################################################
+#
+#   Copyright (c) 2015 PX4 Development Team. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. 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.
+# 3. Neither the name PX4 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.
+#
+############################################################################
+px4_add_module(
+	MODULE platforms__posix__tests__wqueue
+	MAIN wqueue_test
+	SRCS
+		wqueue_main.cpp
+		wqueue_start_posix.cpp
+		wqueue_test.cpp
+	DEPENDS
+	)
@@ -0,0 +1,57 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2015 Mark Charlebois. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name PX4 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.
+ *
+ ****************************************************************************/
+
+/**
+ * @file wqueue_main.cpp
+ * Example for Linux
+ *
+ * @author Mark Charlebois <charlebm@gmail.com>
+ */
+#include "wqueue_test.h"
+
+#include <px4_log.h>
+#include <px4_middleware.h>
+#include <px4_app.h>
+#include <stdio.h>
+
+int PX4_MAIN(int argc, char **argv)
+{
+	px4::init(argc, argv, "wqueue_test");
+
+	PX4_INFO("wqueue hello\n");
+	WQueueTest wq;
+	wq.main();
+
+	PX4_INFO("goodbye\n");
+	return 0;
+}
@@ -0,0 +1,98 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2015 Mark Charlebois. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name PX4 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.
+ *
+ ****************************************************************************/
+
+/**
+ * @file wqueue_start_posix.cpp
+ *
+ * @author Thomas Gubler <thomasgubler@gmail.com>
+ * @author Mark Charlebois <mcharleb@gmail.com>
+ */
+#include "wqueue_test.h"
+
+#include <px4_app.h>
+#include <px4_log.h>
+#include <px4_tasks.h>
+#include <stdio.h>
+#include <string.h>
+#include <sched.h>
+
+static int daemon_task;             /* Handle of deamon task / thread */
+
+//using namespace px4;
+
+extern "C" __EXPORT int wqueue_test_main(int argc, char *argv[]);
+int wqueue_test_main(int argc, char *argv[])
+{
+
+	if (argc < 2) {
+		PX4_INFO("usage: wqueue_test {start|stop|status}\n");
+		return 1;
+	}
+
+	if (!strcmp(argv[1], "start")) {
+
+		if (WQueueTest::appState.isRunning()) {
+			PX4_INFO("already running\n");
+			/* this is not an error */
+			return 0;
+		}
+
+		daemon_task = px4_task_spawn_cmd("wqueue",
+						 SCHED_DEFAULT,
+						 SCHED_PRIORITY_MAX - 5,
+						 2000,
+						 PX4_MAIN,
+						 (argv) ? (char *const *)&argv[2] : (char *const *)nullptr);
+
+		return 0;
+	}
+
+	if (!strcmp(argv[1], "stop")) {
+		WQueueTest::appState.requestExit();
+		return 0;
+	}
+
+	if (!strcmp(argv[1], "status")) {
+		if (WQueueTest::appState.isRunning()) {
+			PX4_INFO("is running\n");
+
+		} else {
+			PX4_INFO("not started\n");
+		}
+
+		return 0;
+	}
+
+	PX4_INFO("usage: wqueue_test {start|stop|status}\n");
+	return 1;
+}
@@ -0,0 +1,113 @@
+
+/****************************************************************************
+ *
+ *   Copyright (C) 2015 Mark Charlebois. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name PX4 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.
+ *
+ ****************************************************************************/
+
+/**
+ * @file wqueue_example.cpp
+ * Example for Linux
+ *
+ * @author Mark Charlebois <charlebm@gmail.com>
+ */
+
+#include "wqueue_test.h"
+
+#include <px4_time.h>
+#include <px4_workqueue.h>
+#include <unistd.h>
+#include <stdio.h>
+
+px4::AppState WQueueTest::appState;
+
+void WQueueTest::hp_worker_cb(void *p)
+{
+	WQueueTest *wqep = (WQueueTest *)p;
+
+	wqep->do_hp_work();
+}
+
+void WQueueTest::lp_worker_cb(void *p)
+{
+	WQueueTest *wqep = (WQueueTest *)p;
+
+	wqep->do_lp_work();
+}
+
+void WQueueTest::do_lp_work()
+{
+	static int iter = 0;
+	printf("done lp work\n");
+
+	if (iter > 5) {
+		_lpwork_done = true;
+	}
+
+	++iter;
+
+	work_queue(LPWORK, &_lpwork, (worker_t)&lp_worker_cb, this, 1000);
+}
+
+void WQueueTest::do_hp_work()
+{
+	static int iter = 0;
+	printf("done hp work\n");
+
+	if (iter > 5) {
+		_hpwork_done = true;
+	}
+
+	++iter;
+
+	// requeue
+	work_queue(HPWORK, &_hpwork, (worker_t)&hp_worker_cb, this, 1000);
+}
+
+int WQueueTest::main()
+{
+	appState.setRunning(true);
+
+	//Put work on HP work queue
+	work_queue(HPWORK, &_hpwork, (worker_t)&hp_worker_cb, this, 1000);
+
+
+	//Put work on LP work queue
+	work_queue(LPWORK, &_lpwork, (worker_t)&lp_worker_cb, this, 1000);
+
+
+	// Wait for work to finsh
+	while (!appState.exitRequested() && !(_hpwork_done && _lpwork_done)) {
+		printf("  Sleeping for 2 sec...\n");
+		sleep(2);
+	}
+
+	return 0;
+}
@@ -0,0 +1,73 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2015 Mark Charlebois. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name PX4 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.
+ *
+ ****************************************************************************/
+
+/**
+ * @file wqueue_test.h
+ * Example app for Linux
+ *
+ * @author Mark Charlebois <charlebm@gmail.com>
+ */
+#pragma once
+
+#include <px4_app.h>
+#include <px4_workqueue.h>
+#include <string.h>
+
+class WQueueTest
+{
+public:
+	WQueueTest() :
+		_lpwork_done(false),
+		_hpwork_done(false)
+	{
+		memset(&_lpwork, 0, sizeof(_lpwork));
+		memset(&_hpwork, 0, sizeof(_hpwork));
+	};
+
+	~WQueueTest() {}
+
+	int main();
+
+	static px4::AppState appState; /* track requests to terminate app */
+private:
+	static void hp_worker_cb(void *p);
+	static void lp_worker_cb(void *p);
+
+	void do_lp_work(void);
+	void do_hp_work(void);
+
+	bool _lpwork_done;
+	bool _hpwork_done;
+	work_s _lpwork;
+	work_s _hpwork;
+};