Move clock functions from sched/ to sched/clock

12 files changed, 1608 insertions, 0 deletions

diff --git a/nuttx/sched/clock/Make.defs b/nuttx/sched/clock/Make.defs
new file mode 100644
index 000000000..aa7dce762
--- /dev/null
+++ b/nuttx/sched/clock/Make.defs
@@ -0,0 +1,43 @@
+############################################################################
+# sched/clock/Make.defs
+#
+#   Copyright (C) 2014 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.
+#
+############################################################################
+
+CLOCK_SRCS  = clock_initialize.c clock_settime.c clock_gettime.c clock_getres.c
+CLOCK_SRCS += clock_time2ticks.c clock_abstime2ticks.c clock_ticks2time.c
+CLOCK_SRCS += clock_gettimeofday.c clock_systimer.c
+
+# Include clock build support
+
+DEPPATH += --dep-path clock
+VPATH += :clock
diff --git a/nuttx/sched/clock/clock.h b/nuttx/sched/clock/clock.h
new file mode 100644
index 000000000..976ec117f
--- /dev/null
+++ b/nuttx/sched/clock/clock.h
@@ -0,0 +1,93 @@
+/********************************************************************************
+ * sched/clock/clock.h
+ *
+ *   Copyright (C) 2007-2009, 2014 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.
+ *
+ ********************************************************************************/
+
+#ifndef __SCHED_CLOCK_CLOCK_H
+#define __SCHED_CLOCK_CLOCK_H
+
+/********************************************************************************
+ * Included Files
+ ********************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+
+#include <nuttx/clock.h>
+#include <nuttx/compiler.h>
+
+/********************************************************************************
+ * Pre-processor Definitions
+ ********************************************************************************/
+/* Configuration ************************************************************/
+/* If CONFIG_SYSTEM_TIME64 is selected and the CPU supports long long types,
+ * then a 64-bit system time will be used.
+ */
+
+#ifndef CONFIG_HAVE_LONG_LONG
+#  undef CONFIG_SYSTEM_TIME64
+#endif
+
+/********************************************************************************
+ * Public Type Definitions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Global Variables
+ ********************************************************************************/
+
+#ifdef CONFIG_SYSTEM_TIME64
+extern uint64_t        g_tickbias;
+#else
+extern uint32_t        g_tickbias;
+#endif
+
+extern struct timespec g_basetime;
+
+/********************************************************************************
+ * Public Function Prototypes
+ ********************************************************************************/
+
+void weak_function clock_initialize(void);
+#ifndef CONFIG_SCHED_TICKLESS
+void weak_function clock_timer(void);
+#endif
+
+int    clock_abstime2ticks(clockid_t clockid,
+                           FAR const struct timespec *abstime,
+                           FAR int *ticks);
+int    clock_time2ticks(FAR const struct timespec *reltime, FAR int *ticks);
+int    clock_ticks2time(int ticks, FAR struct timespec *reltime);
+
+#endif /* __SCHED_CLOCK_CLOCK_H */
diff --git a/nuttx/sched/clock/clock_abstime2ticks.c b/nuttx/sched/clock/clock_abstime2ticks.c
new file mode 100644
index 000000000..1f8845d05
--- /dev/null
+++ b/nuttx/sched/clock/clock_abstime2ticks.c
@@ -0,0 +1,126 @@
+/********************************************************************************
+ * sched/clock/clock_abstime2ticks.c
+ *
+ *   Copyright (C) 2007, 2008, 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 <nuttx/config.h>
+
+#include <time.h>
+#include <errno.h>
+#include <debug.h>
+#include "clock/clock.h"
+
+/********************************************************************************
+ * Pre-processor Definitions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Type Declarations
+ ********************************************************************************/
+
+/********************************************************************************
+ * Global Variables
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Variables
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Public Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Name: clock_abstime2ticks
+ *
+ * Description:
+ *   Convert an absolute timespec delay to system timer ticks.
+ *
+ * Parameters:
+ *   clockid - The timing source to use in the conversion
+ *   reltime - Convert this absolue time to system clock ticks.
+ *   ticks - Return the converted number of ticks here.
+ *
+ * Return Value:
+ *   OK on success; A non-zero error number on failure;
+ *
+ * Assumptions:
+ *   Interrupts should be disabled so that the time is not changing during the
+ *   calculation
+ *
+ ********************************************************************************/
+
+int clock_abstime2ticks(clockid_t clockid, FAR const struct timespec *abstime,
+                        FAR int *ticks)
+{
+  struct timespec currtime;
+  struct timespec reltime;
+  int             ret;
+
+  /* Convert the timespec to clock ticks.  NOTE: Here we use internal knowledge
+   * that CLOCK_REALTIME is defined to be zero!
+   */
+
+  ret = clock_gettime(clockid, &currtime);
+  if (ret)
+    {
+      return EINVAL;
+    }
+
+  /* The relative time to wait is the absolute time minus the current time. */
+
+  reltime.tv_nsec = (abstime->tv_nsec - currtime.tv_nsec);
+  reltime.tv_sec  = (abstime->tv_sec  - currtime.tv_sec);
+
+  /* Check if we were supposed to borrow from the seconds to borrow from the
+   * seconds
+   */
+
+  if (reltime.tv_nsec < 0)
+    {
+      reltime.tv_nsec += NSEC_PER_SEC;
+      reltime.tv_sec  -= 1;
+    }
+
+  /* Convert this relative time into clock ticks. */
+
+  return clock_time2ticks(&reltime, ticks);
+}
diff --git a/nuttx/sched/clock/clock_dow.c b/nuttx/sched/clock/clock_dow.c
new file mode 100644
index 000000000..00e9703bc
--- /dev/null
+++ b/nuttx/sched/clock/clock_dow.c
@@ -0,0 +1,88 @@
+/****************************************************************************
+ * sched/clock/clock_dow.c
+ *
+ *   Copyright (C) 2012 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 <nuttx/config.h>
+
+#include <stdint.h>
+
+#include <nuttx/clock.h>
+
+#include "clock/clock.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/* 23 * (month + 1) / 9, month = 0..11 */
+
+static const uint8_t g_lookup[12] = {2, 5, 7, 10, 12, 15, 17, 20, 23, 25, 28, 30};
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: clock_dow
+ *
+ * Description:
+ *   Calculate the day of week (DOW) from they year month and day.  Based on
+ *   an algorithm pubished in 1990 by Michael Keith and Tom Craver with some
+ *   tweaks to handle months in the range 0-11.
+ *
+ * Parameters:
+ *   year  - year (e.g., 1988)
+ *   month - 0 through 11
+ *   day   - 1 through 31
+ *
+ * Return Value:
+ *   The day of the week as days since Sunday: 0 = Sunday, 1 = Monday, etc.
+ *
+ * Assumptions:
+ *
+ ****************************************************************************/
+
+int clock_dow(int year, int month, int day)
+{
+  day += month < 2 ? year-- : year - 2;
+  return ((int)g_lookup[month] + day + 4 + year/4 - year/100 + year/400) % 7;
+}
diff --git a/nuttx/sched/clock/clock_getres.c b/nuttx/sched/clock/clock_getres.c
new file mode 100644
index 000000000..5f4a0b6e8
--- /dev/null
+++ b/nuttx/sched/clock/clock_getres.c
@@ -0,0 +1,114 @@
+/************************************************************************
+ * sched/clock/clock_getres.c
+ *
+ *   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.
+ *
+ ************************************************************************/
+
+/************************************************************************
+ * Included Files
+ ************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <time.h>
+#include <errno.h>
+#include <debug.h>
+
+#include "clock/clock.h"
+
+/************************************************************************
+ * Definitions
+ ************************************************************************/
+
+/************************************************************************
+ * Private Type Declarations
+ ************************************************************************/
+
+/************************************************************************
+ * Private Function Prototypes
+ ************************************************************************/
+
+/**********************************************************************
+ * Public Constant Data
+ **********************************************************************/
+
+/************************************************************************
+ * Public Variables
+ ************************************************************************/
+
+/**********************************************************************
+ * Private Variables
+ **********************************************************************/
+
+/************************************************************************
+ * Private Functions
+ ************************************************************************/
+
+/************************************************************************
+ * Public Functions
+ ************************************************************************/
+
+/************************************************************************
+ * Name: clock_getres
+ *
+ * Description:
+ *   Clock Functions based on POSIX APIs
+ *
+ ************************************************************************/
+
+int clock_getres(clockid_t clock_id, struct timespec *res)
+{
+  int      ret = OK;
+
+  sdbg("clock_id=%d\n", clock_id);
+
+  /* Only CLOCK_REALTIME is supported */
+
+  if (clock_id != CLOCK_REALTIME)
+    {
+      sdbg("Returning ERROR\n");
+      set_errno(EINVAL);
+      ret = ERROR;
+    }
+  else
+    {
+      /* Form the timspec using clock resolution in nanoseconds */
+
+      res->tv_sec  = 0;
+      res->tv_nsec = NSEC_PER_TICK;
+
+      sdbg("Returning res=(%d,%d)\n", (int)res->tv_sec, (int)res->tv_nsec);
+    }
+
+  return ret;
+}
diff --git a/nuttx/sched/clock/clock_gettime.c b/nuttx/sched/clock/clock_gettime.c
new file mode 100644
index 000000000..d0cc48370
--- /dev/null
+++ b/nuttx/sched/clock/clock_gettime.c
@@ -0,0 +1,225 @@
+/************************************************************************
+ * sched/clock/clock_gettime.c
+ *
+ *   Copyright (C) 2007, 2009, 2011, 2014 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 <nuttx/config.h>
+#include <nuttx/rtc.h>
+
+#include <stdint.h>
+#include <time.h>
+#include <assert.h>
+#include <errno.h>
+#include <debug.h>
+
+#include <arch/irq.h>
+
+#include "clock/clock.h"
+
+/************************************************************************
+ * Pre-processor Definitions
+ ************************************************************************/
+
+/************************************************************************
+ * Private Type Declarations
+ ************************************************************************/
+
+/************************************************************************
+ * Private Function Prototypes
+ ************************************************************************/
+
+/**********************************************************************
+ * Public Constant Data
+ **********************************************************************/
+
+/************************************************************************
+ * Public Variables
+ ************************************************************************/
+
+/**********************************************************************
+ * Private Variables
+ **********************************************************************/
+
+/************************************************************************
+ * Private Functions
+ ************************************************************************/
+
+/************************************************************************
+ * Public Functions
+ ************************************************************************/
+
+/************************************************************************
+ * Name: clock_gettime
+ *
+ * Description:
+ *   Clock Functions based on POSIX APIs
+ *
+ ************************************************************************/
+
+int clock_gettime(clockid_t clock_id, struct timespec *tp)
+{
+#ifdef CONFIG_SYSTEM_TIME64
+  uint64_t msecs;
+  uint64_t secs;
+  uint64_t nsecs;
+#else
+  uint32_t msecs;
+  uint32_t secs;
+  uint32_t nsecs;
+#endif
+  uint32_t carry;
+  int ret = OK;
+
+  sdbg("clock_id=%d\n", clock_id);
+  DEBUGASSERT(tp != NULL);
+
+#ifdef CONFIG_CLOCK_MONOTONIC
+  /* CLOCK_MONOTONIC is an optional under POSIX: "If the Monotonic Clock
+   * option is supported, all implementations shall support a clock_id
+   * of CLOCK_MONOTONIC defined in <time.h>. This clock represents the
+   * monotonic clock for the system. For this clock, the value returned
+   * by clock_gettime() represents the amount of time (in seconds and
+   * nanoseconds) since an unspecified point in the past (for example,
+   * system start-up time, or the Epoch). This point does not change
+   * after system start-up time. The value of the CLOCK_MONOTONIC clock
+   * cannot be set via clock_settime(). This function shall fail if it
+   * is invoked with a clock_id argument of CLOCK_MONOTONIC."
+   */
+
+  if (clock_id == CLOCK_MONOTONIC)
+    {
+      /* Get the time since power-on in seconds and milliseconds */
+
+      msecs = TICK2MSEC(clock_systimer());
+      secs  = msecs / MSEC_PER_SEC;
+
+      /* Return the elapsed time in seconds and nanoseconds */
+
+      nsecs = (msecs - (secs * MSEC_PER_SEC)) * NSEC_PER_MSEC;
+
+      tp->tv_sec  = (time_t)secs;
+      tp->tv_nsec = (long)nsecs;
+    }
+  else
+#endif
+
+  /* CLOCK_REALTIME - POSIX demands this to be present.  CLOCK_REALTIME
+   * represents the machine's best-guess as to the current wall-clock,
+   * time-of-day time. This means that CLOCK_REALTIME can jump forward and
+   * backward as the system time-of-day clock is changed.
+   *
+   * If an RTC is supported, then the non-standard CLOCK_ACTIVETIME is also
+   * supported to manage time based on the system timer interrupt separately
+   * from the RTC.  This may be necessary, for example, in certain cases where
+   * the system timer interrupt has been stopped in low power modes.
+   */
+
+#ifdef CONFIG_RTC
+  if (clock_id == CLOCK_REALTIME || clock_id == CLOCK_ACTIVETIME)
+#else
+  if (clock_id == CLOCK_REALTIME)
+#endif
+    {
+      /* Do we have a high-resolution RTC that can provide us with the time? */
+
+#ifdef CONFIG_RTC_HIRES
+      if (g_rtc_enabled && clock_id != CLOCK_ACTIVETIME)
+        {
+          /* Yes.. Get the hi-resolution time from the RTC unless the caller
+           * has specifically asked for the system timer (CLOCK_ACTIVETIME)
+           */
+
+          ret = up_rtc_gettime(tp);
+        }
+      else
+#endif
+        {
+          /* Get the elapsed time since the time-of-day was last set.
+           * clock_systimer() provides the number of clock times since
+           * power was applied; the bias value corresponds to the time
+           * when the time-of-day was last set.
+           */
+
+          msecs = TICK2MSEC((clock_systimer() - g_tickbias));
+
+          sdbg("msecs = %d g_tickbias=%d\n",
+               (int)msecs, (int)g_tickbias);
+
+          /* Get the elapsed time in seconds and nanoseconds. */
+
+          secs  = msecs / MSEC_PER_SEC;
+          nsecs = (msecs - (secs * MSEC_PER_SEC)) * NSEC_PER_MSEC;
+
+          sdbg("secs = %d + %d nsecs = %d + %d\n",
+               (int)msecs, (int)g_basetime.tv_sec,
+               (int)nsecs, (int)g_basetime.tv_nsec);
+
+          /* Add the base time to this.  The base time is the time-of-day
+           * setting.  When added to the elapsed time since the time-of-day
+           * was last set, this gives us the current time.
+           */
+
+          secs  += (uint32_t)g_basetime.tv_sec;
+          nsecs += (uint32_t)g_basetime.tv_nsec;
+
+          /* Handle carry to seconds. */
+
+          if (nsecs > NSEC_PER_SEC)
+            {
+              carry  = nsecs / NSEC_PER_SEC;
+              secs  += carry;
+              nsecs -= (carry * NSEC_PER_SEC);
+            }
+
+          /* And return the result to the caller. */
+
+          tp->tv_sec  = (time_t)secs;
+          tp->tv_nsec = (long)nsecs;
+        }
+
+      sdbg("Returning tp=(%d,%d)\n", (int)tp->tv_sec, (int)tp->tv_nsec);
+    }
+  else
+    {
+      sdbg("Returning ERROR\n");
+
+      set_errno(EINVAL);
+      ret = ERROR;
+    }
+
+  return ret;
+}
diff --git a/nuttx/sched/clock/clock_gettimeofday.c b/nuttx/sched/clock/clock_gettimeofday.c
new file mode 100644
index 000000000..46db6e698
--- /dev/null
+++ b/nuttx/sched/clock/clock_gettimeofday.c
@@ -0,0 +1,113 @@
+/****************************************************************************
+ * sched/clock/clock_gettimeofday.c
+ *
+ *   Copyright (C) 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/time.h>
+#include <errno.h>
+#include <debug.h>
+
+#include "clock/clock.h"
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/**************************************************************************
+ * Public Constant Data
+ **************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/**************************************************************************
+ * Private Variables
+ **************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: gettimeofday
+ *
+ * Description:
+ *  Get the current time
+ *
+ ****************************************************************************/
+
+int gettimeofday(struct timeval *tp, void *tzp)
+{
+  struct timespec ts;
+  int ret;
+
+#ifdef CONFIG_DEBUG
+  if (!tp)
+    {
+      errno = EINVAL;
+      return ERROR;
+    }
+#endif
+
+  /* Let clock_gettime do most of the work */
+
+  ret = clock_gettime(CLOCK_REALTIME, &ts);
+  if (ret == OK)
+    {
+       /* Convert the struct timespec to a struct timeval */
+
+       tp->tv_sec  = ts.tv_sec;
+       tp->tv_usec = ts.tv_nsec / NSEC_PER_USEC;
+    }
+
+  return ret;
+}
diff --git a/nuttx/sched/clock/clock_initialize.c b/nuttx/sched/clock/clock_initialize.c
new file mode 100644
index 000000000..62a41cd69
--- /dev/null
+++ b/nuttx/sched/clock/clock_initialize.c
@@ -0,0 +1,280 @@
+/****************************************************************************
+ * sched/clock/clock_initialize.c
+ *
+ *   Copyright (C) 2007, 2009, 2011-2012 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 <nuttx/config.h>
+#include <nuttx/compiler.h>
+
+#include <stdint.h>
+#include <time.h>
+#include <errno.h>
+#include <debug.h>
+
+#ifdef CONFIG_RTC
+#  include <arch/irq.h>
+#endif
+
+#include <nuttx/clock.h>
+#include <nuttx/time.h>
+#include <nuttx/rtc.h>
+
+#include "clock/clock.h"
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+/* Standard time definitions (in units of seconds) */
+
+#define SEC_PER_MIN  ((time_t)60)
+#define SEC_PER_HOUR ((time_t)60 * SEC_PER_MIN)
+#define SEC_PER_DAY  ((time_t)24 * SEC_PER_HOUR)
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/**************************************************************************
+ * Public Constant Data
+ **************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+#ifndef CONFIG_SCHED_TICKLESS
+#ifdef CONFIG_SYSTEM_TIME64
+volatile uint64_t g_system_timer;
+#else
+volatile uint32_t g_system_timer;
+#endif
+#endif
+
+#ifdef CONFIG_SYSTEM_TIME64
+uint64_t          g_tickbias;
+#else
+uint32_t          g_tickbias;
+#endif
+
+struct timespec   g_basetime;
+
+/**************************************************************************
+ * Private Variables
+ **************************************************************************/
+
+/**************************************************************************
+ * Private Functions
+ **************************************************************************/
+
+/****************************************************************************
+ * Name: clock_basetime
+ *
+ * Description:
+ *   Get the initial time value from the best source available.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_RTC
+#if defined(CONFIG_RTC_DATETIME)
+/* Initialize the system time using a broken out date/time structure */
+
+static inline void clock_basetime(FAR struct timespec *tp)
+{
+  struct tm rtctime;
+
+  /* Get the broken-out time from the date/time RTC. */
+
+  (void)up_rtc_getdatetime(&rtctime);
+
+  /* And use the broken-out time to initialize the system time */
+
+  tp->tv_sec  = mktime(&rtctime);
+  tp->tv_nsec = 0;
+}
+
+#elif defined(CONFIG_RTC_HIRES)
+
+/* Initialize the system time using a high-resolution structure */
+
+static inline void clock_basetime(FAR struct timespec *tp)
+{
+  /* Get the complete time from the hi-res RTC. */
+
+  (void)up_rtc_gettime(tp);
+}
+
+#else
+
+/* Initialize the system time using seconds only */
+
+static inline void clock_basetime(FAR struct timespec *tp)
+{
+  /* Get the seconds (only) from the lo-resolution RTC */
+
+  tp->tv_sec  = up_rtc_time();
+  tp->tv_nsec = 0;
+}
+
+#endif /* CONFIG_RTC_HIRES */
+#else /* CONFIG_RTC */
+
+static inline void clock_basetime(FAR struct timespec *tp)
+{
+  time_t jdn = 0;
+
+  /* Get the EPOCH-relative julian date from the calendar year,
+   * month, and date
+   */
+
+  jdn = clock_calendar2utc(CONFIG_START_YEAR, CONFIG_START_MONTH,
+                           CONFIG_START_DAY);
+
+  /* Set the base time as seconds into this julian day. */
+
+  tp->tv_sec  = jdn * SEC_PER_DAY;
+  tp->tv_nsec = 0;
+}
+
+#endif /* CONFIG_RTC */
+
+/****************************************************************************
+ * Name: clock_inittime
+ *
+ * Description:
+ *   Get the initial time value from the best source available.
+ *
+ ****************************************************************************/
+
+static void clock_inittime(void)
+{
+  /* (Re-)initialize the time value to match the RTC */
+
+  clock_basetime(&g_basetime);
+#ifndef CONFIG_SCHED_TICKLESS
+  g_system_timer = 0;
+#endif
+  g_tickbias     = 0;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: clock_initialize
+ *
+ * Description:
+ *   Perform one-time initialization of the timing facilities.
+ *
+ ****************************************************************************/
+
+void clock_initialize(void)
+{
+  /* Initialize the RTC hardware */
+
+#ifdef CONFIG_RTC
+  up_rtcinitialize();
+#endif
+
+  /* Initialize the time value to match the RTC */
+
+  clock_inittime();
+}
+
+/****************************************************************************
+ * Name: clock_synchronize
+ *
+ * Description:
+ *   Synchronize the system timer to a hardware RTC.  This operation is
+ *   normally performed automatically by the system during clock
+ *   initialization.  However, the user may also need to explicitly re-
+ *   synchronize the system timer to the RTC under certain conditions where
+ *   the system timer is known to be in error.  For example, in certain low-
+ *   power states, the system timer may be stopped but the RTC will continue
+ *   keep correct time.  After recovering from such low-power state, this
+ *   function should be called to restore the correct system time.
+ *
+ *   Calling this function could result in system time going "backward" in
+ *   time, especially with certain lower resolution RTC implementations.
+ *   Time going backward could have bad consequences if there are ongoing
+ *   timers and delays.  So use this interface with care.
+ *
+ * Parameters:
+ *   None
+ *
+ * Return Value:
+ *   None
+ *
+ * Assumptions:
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_RTC
+void clock_synchronize(void)
+{
+  irqstate_t flags;
+
+  /* Re-initialize the time value to match the RTC */
+
+  flags = irqsave();
+  clock_inittime();
+  irqrestore(flags);
+}
+#endif
+
+/****************************************************************************
+ * Name: clock_timer
+ *
+ * Description:
+ *   This function must be called once every time the real time clock
+ *   interrupt occurs.  The interval of this clock interrupt must be
+ *   USEC_PER_TICK
+ *
+ ****************************************************************************/
+
+#ifndef CONFIG_SCHED_TICKLESS
+void clock_timer(void)
+{
+  /* Increment the per-tick system counter */
+
+  g_system_timer++;
+}
+#endif
diff --git a/nuttx/sched/clock/clock_settime.c b/nuttx/sched/clock/clock_settime.c
new file mode 100644
index 000000000..8d26da155
--- /dev/null
+++ b/nuttx/sched/clock/clock_settime.c
@@ -0,0 +1,149 @@
+/************************************************************************
+ * sched/clock/clock_settime.c
+ *
+ *   Copyright (C) 2007, 2009, 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.
+ *
+ ************************************************************************/
+
+/************************************************************************
+ * Included Files
+ ************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/rtc.h>
+
+#include <time.h>
+#include <assert.h>
+#include <errno.h>
+#include <debug.h>
+
+#include <arch/irq.h>
+#include "clock/clock.h"
+
+/************************************************************************
+ * Definitions
+ ************************************************************************/
+
+/************************************************************************
+ * Private Type Declarations
+ ************************************************************************/
+
+/************************************************************************
+ * Private Function Prototypes
+ ************************************************************************/
+
+/**********************************************************************
+ * Public Constant Data
+ **********************************************************************/
+
+/************************************************************************
+ * Public Variables
+ ************************************************************************/
+
+/**********************************************************************
+ * Private Variables
+ **********************************************************************/
+
+/************************************************************************
+ * Private Functions
+ ************************************************************************/
+
+/************************************************************************
+ * Public Functions
+ ************************************************************************/
+
+/************************************************************************
+ * Name: clock_settime
+ *
+ * Description:
+ *   Clock Functions based on POSIX APIs
+ *
+ ************************************************************************/
+
+int clock_settime(clockid_t clock_id, FAR const struct timespec *tp)
+{
+  irqstate_t flags;
+  int ret = OK;
+
+  sdbg("clock_id=%d\n", clock_id);
+  DEBUGASSERT(tp != NULL);
+
+  /* CLOCK_REALTIME - POSIX demands this to be present. This is the wall
+   * time clock.
+   */
+
+#ifdef CONFIG_RTC
+  if (clock_id == CLOCK_REALTIME || clock_id == CLOCK_ACTIVETIME)
+#else
+  if (clock_id == CLOCK_REALTIME)
+#endif
+    {
+      /* Interrupts are disabled here so that the in-memory time
+       * representation and the RTC setting will be as close as
+       * possible.
+       */
+
+      flags = irqsave();
+
+      /* Save the new base time. */
+
+      g_basetime.tv_sec  = tp->tv_sec;
+      g_basetime.tv_nsec = tp->tv_nsec;
+
+      /* Get the elapsed time since power up (in milliseconds) biased
+       * as appropriate.
+       */
+
+      g_tickbias = clock_systimer();
+
+      /* Setup the RTC (lo- or high-res) */
+
+#ifdef CONFIG_RTC
+      if (g_rtc_enabled && clock_id != CLOCK_ACTIVETIME)
+        {
+          up_rtc_settime(tp);
+        }
+#endif
+      irqrestore(flags);
+
+      sdbg("basetime=(%d,%d) tickbias=%d\n",
+          (int)g_basetime.tv_sec, (int)g_basetime.tv_nsec,
+          (int)g_tickbias);
+    }
+  else
+    {
+      sdbg("Returning ERROR\n");
+      set_errno(EINVAL);
+      ret = ERROR;
+    }
+
+  return ret;
+}
diff --git a/nuttx/sched/clock/clock_systimer.c b/nuttx/sched/clock/clock_systimer.c
new file mode 100644
index 000000000..1d24803ef
--- /dev/null
+++ b/nuttx/sched/clock/clock_systimer.c
@@ -0,0 +1,147 @@
+/****************************************************************************
+ * sched/clock/clock_systimer.c
+ *
+ *   Copyright (C) 2011, 2014 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 <nuttx/config.h>
+
+#include <stdint.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/clock.h>
+
+#include "clock/clock.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: clock_systimer
+ *
+ * Description:
+ *   Return the current value of the 32-bit system timer counter
+ *
+ * Parameters:
+ *   None
+ *
+ * Return Value:
+ *   The current value of the system timer counter
+ *
+ * Assumptions:
+ *
+ ****************************************************************************/
+
+#if !defined(clock_systimer) /* See nuttx/clock.h */
+uint32_t clock_systimer(void)
+{
+#ifdef CONFIG_SCHED_TICKLESS
+  struct timespec ts;
+  uint64_t tmp;
+
+  /* Get the time from the platform specific hardware */
+
+  (void)up_timer_gettime(&ts);
+
+  /* Convert to a 64- then 32-bit value */
+
+  tmp = MSEC2TICK(1000 * (uint64_t)ts.tv_sec + (uint64_t)ts.tv_nsec / 1000000);
+  return (uint32_t)(tmp & 0x00000000ffffffff);
+
+#else
+
+#ifdef CONFIG_SYSTEM_TIME64
+  /* Return the current system time truncated to 32-bits */
+
+  return (uint32_t)(g_system_timer & 0x00000000ffffffff);
+#else
+  /* Return the current system time */
+
+  return g_system_timer;
+#endif
+
+#endif
+}
+#endif
+
+/****************************************************************************
+ * Name: clock_systimer64
+ *
+ * Description:
+ *   Return the current value of the 64-bit system timer counter
+ *
+ * Parameters:
+ *   None
+ *
+ * Return Value:
+ *   The current value of the system timer counter
+ *
+ * Assumptions:
+ *
+ ****************************************************************************/
+
+#if !defined(clock_systimer) /* See nuttx/clock.h */
+#ifdef CONFIG_SYSTEM_TIME64
+uint64_t clock_systimer64(void)
+{
+#ifdef CONFIG_SCHED_TICKLESS
+  struct timespec ts;
+
+  /* Get the time from the platform specific hardware */
+
+  (void)up_timer_gettime(&ts);
+
+  /* Convert to a 64- then 32-bit value */
+
+  return MSEC2TICK(1000 * (uint64_t)ts.tv_sec + (uint64_t)ts.tv_nsec / 1000000);
+
+#else
+  /* Return the current system time */
+
+  return g_system_timer;
+#endif
+}
+#endif
+#endif
diff --git a/nuttx/sched/clock/clock_ticks2time.c b/nuttx/sched/clock/clock_ticks2time.c
new file mode 100644
index 000000000..416487667
--- /dev/null
+++ b/nuttx/sched/clock/clock_ticks2time.c
@@ -0,0 +1,94 @@
+/********************************************************************************
+ * sched/clock/clock_ticks2time.c
+ *
+ *   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.
+ *
+ ********************************************************************************/
+
+/********************************************************************************
+ * Included Files
+ ********************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <time.h>
+#include "clock/clock.h"
+
+/********************************************************************************
+ * Definitions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Type Declarations
+ ********************************************************************************/
+
+/********************************************************************************
+ * Global Variables
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Variables
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Public Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Name: clock_ticks2time
+ *
+ * Description:
+ *   Convert the system time tick value to a relative time.
+ *
+ * Parameters:
+ *   ticks - The number of system time ticks to convert.
+ *   reltime - Return the converted system time here.
+ *
+ * Return Value:
+ *   Always returns OK
+ *
+ * Assumptions:
+ *
+ ********************************************************************************/
+
+int clock_ticks2time(int ticks, FAR struct timespec *reltime)
+{
+  int remainder;
+
+  reltime->tv_sec  = ticks / TICK_PER_SEC;
+  remainder        = ticks - TICK_PER_SEC * reltime->tv_sec;
+  reltime->tv_nsec = remainder * NSEC_PER_TICK;
+  return OK;
+}
diff --git a/nuttx/sched/clock/clock_time2ticks.c b/nuttx/sched/clock/clock_time2ticks.c
new file mode 100644
index 000000000..c54cc949b
--- /dev/null
+++ b/nuttx/sched/clock/clock_time2ticks.c
@@ -0,0 +1,136 @@
+/********************************************************************************
+ * sched/clock/clock_time2ticks.c
+ *
+ *   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.
+ *
+ ********************************************************************************/
+
+/********************************************************************************
+ * Included Files
+ ********************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+#include <time.h>
+
+#include "clock/clock.h"
+
+/********************************************************************************
+ * Definitions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Type Declarations
+ ********************************************************************************/
+
+/********************************************************************************
+ * Global Variables
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Variables
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Public Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Name: clock_time2ticks
+ *
+ * Description:
+ *   Convert a timespec delay to system timer ticks.  This function is suitable
+ *   for calculating relative time delays and does not depend on the other
+ *   clock_* logic.
+ *
+ * Parameters:
+ *   reltime - Convert this relative time to system clock ticks.
+ *   ticks - Return the converted number of ticks here.
+ *
+ * Return Value:
+ *   Always returns OK
+ *
+ * Assumptions:
+ *
+ ********************************************************************************/
+
+int clock_time2ticks(FAR const struct timespec *reltime, FAR int *ticks)
+{
+#ifdef CONFIG_HAVE_LONG_LONG
+  int64_t relnsec;
+
+  /* Convert the relative time into nanoseconds.  The range of the int64_t is
+   * sufficiently large that there is no real need for range checking.
+   */
+
+  relnsec = (int64_t)reltime->tv_sec * NSEC_PER_SEC +
+            (int64_t)reltime->tv_nsec;
+
+  /* Convert nanoseconds to clock ticks, rounding up to the smallest integer
+   * that is greater than or equal to the exact number of tick.
+   */
+
+  *ticks = (int)((relnsec + NSEC_PER_TICK - 1) / NSEC_PER_TICK);
+  return OK;
+#else
+  int32_t relusec;
+
+  /* This function uses an int32_t to only the relative time in microseconds.
+   * that means that the maximum supported relative time is 2,147,487.647
+   * seconds
+   */
+
+#if 0 // overkill
+  DEBUGASSERT(reltime->tv_sec  <  2147487 ||
+              reltime->tv_sec  == 2147487 &&
+              reltime->tv_nsec <= 647 * NSEC_PER_MSEC);
+#endif
+
+  /* Convert the relative time into microseconds, rounding up to the smallest
+   * value that is greater than or equal to the exact number of microseconds.
+   */
+
+  relusec = reltime->tv_sec * USEC_PER_SEC +
+            (reltime->tv_nsec + NSEC_PER_USEC - 1) / NSEC_PER_USEC;
+
+  /* Convert microseconds to clock ticks, rounding up to the smallest integer
+   * that is greater than or equal to the exact number of tick.
+   */
+
+  *ticks = (int)((relusec + USEC_PER_TICK - 1) / USEC_PER_TICK);
+  return OK;
+#endif
+}