sched/sched: Part 2: Add high-resolution timer (hrtimer) and os tick support with hrtimer to NuttX

arch/tricore/Kconfig

@@ -42,6 +42,7 @@ config ARCH_CHIP_TC397
 	select ALARM_ARCH
 	select ONESHOT
 	select ONESHOT_COUNT
+	select SYSTEM_TIME64
 	---help---
 		AURIX TC39x family: TC397
 

drivers/timers/arch_alarm.c

@@ -118,6 +118,9 @@ static void ndelay_accurate(unsigned long nanoseconds)
 static void oneshot_callback(FAR struct oneshot_lowerhalf_s *lower,
                              FAR void *arg)
 {
+#ifdef CONFIG_HRTIMER
+  nxsched_process_hrtimer();
+#else
   clock_t now;
 
   ONESHOT_TICK_CURRENT(g_oneshot_lower, &now);
@@ -138,6 +141,7 @@ static void oneshot_callback(FAR struct oneshot_lowerhalf_s *lower,
     }
 
   ONESHOT_TICK_ABSOLUTE(g_oneshot_lower, now + 1);
+#  endif
 #endif
 }
 

include/nuttx/arch.h

@@ -2442,6 +2442,10 @@ void up_ndelay(unsigned long nanoseconds);
 void nxsched_process_timer(void);
 #endif
 
+#ifdef CONFIG_HRTIMER
+void nxsched_process_hrtimer(void);
+#endif
+
 /****************************************************************************
  * Name:  nxsched_timer_expiration
  *

sched/hrtimer/hrtimer.h

@@ -120,7 +120,7 @@ static inline_function
 int hrtimer_starttimer(uint64_t ns)
 {
   struct timespec ts;
-  int ret;
+  int ret = OK;
 
   /* Convert nanoseconds to timespec */
 

sched/sched/CMakeLists.txt

@@ -118,4 +118,8 @@ if(CONFIG_SMP)
   list(APPEND SRCS sched_smp.c)
 endif()
 
+if(CONFIG_HRTIMER)
+  list(APPEND SRCS sched_processhrtimer.c)
+endif()
+
 target_sources(sched PRIVATE ${SRCS})

sched/sched/Make.defs

@@ -100,6 +100,10 @@ ifeq ($(CONFIG_SMP),y)
 CSRCS += sched_smp.c
 endif
 
+ifeq ($(CONFIG_HRTIMER),y)
+CSRCS += sched_processhrtimer.c
+endif
+
 # Include sched build support
 
 DEPPATH += --dep-path sched

sched/sched/sched.h

@@ -37,6 +37,7 @@
 #include <nuttx/queue.h>
 #include <nuttx/kmalloc.h>
 #include <nuttx/spinlock.h>
+#include "hrtimer/hrtimer.h"
 
 /****************************************************************************
  * Pre-processor Definitions
@@ -307,6 +308,10 @@ extern volatile spinlock_t g_cpu_tasklistlock;
  * Public Function Prototypes
  ****************************************************************************/
 
+#if defined(CONFIG_HRTIMER) && defined(CONFIG_SCHED_TICKLESS)
+int nxsched_hrtimer_start(clock_t ticks);
+#endif
+
 int nxthread_create(FAR const char *name, uint8_t ttype, int priority,
                     FAR void *stack_addr, int stack_size, main_t entry,
                     FAR char * const argv[], FAR char * const envp[]);

sched/sched/sched_processhrtimer.c

@@ -0,0 +1,149 @@
+/****************************************************************************
+ * sched/sched/sched_processhrtimer.c
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/compiler.h>
+#include <time.h>
+
+#include "sched/sched.h"
+#include "hrtimer/hrtimer.h"
+#include "clock/clock.h"
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/* Global high-resolution timer instance used by the scheduler */
+
+static hrtimer_t g_nxsched_hrtimer;
+
+/* Whether the scheduler high-resolution timer has been initialized */
+
+static bool g_sched_hrtimer_inited = false;
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: nxsched_hrtimer_callback
+ *
+ * Description:
+ *   High-resolution timer callback used for scheduler tick processing.
+ *
+ *   This callback updates the scheduler state and arms the next timer
+ *   event. The behavior differs depending on whether tickless mode is
+ *   enabled:
+ *
+ *   - In tickless mode, nxsched_tick_expiration() determines the next
+ *     expiration point.
+ *   - In non-tickless mode, a tick is generated unconditionally at
+ *     every timer interval.
+ *
+ * Input Parameters:
+ *   hrtimer - Pointer to the high-resolution timer instance that expired.
+ *
+ * Returned Value:
+ *   None.
+ *
+ ****************************************************************************/
+
+static uint32_t nxsched_hrtimer_callback(FAR hrtimer_t *hrtimer)
+{
+#ifdef CONFIG_SCHED_TICKLESS
+  uint64_t now = hrtimer_gettime();
+  nxsched_tick_expiration(NSEC2TICK(now));
+#else
+
+  /* Process a single scheduler tick */
+
+  nxsched_process_timer();
+
+  /* Schedule the next tick relative to now */
+
+  return NSEC_PER_TICK;
+#endif
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+#ifdef CONFIG_SCHED_TICKLESS
+int nxsched_hrtimer_start(clock_t ticks)
+{
+  return hrtimer_start(&g_nxsched_hrtimer,
+                       hrtimer->expired + ticks * NSEC_PER_TICK,
+                       HRTIMER_MODE_ABS);
+}
+#endif
+
+/****************************************************************************
+ * Name: nxsched_process_hrtimer
+ *
+ * Description:
+ *   Process pending high-resolution timer events for the scheduler.
+ *
+ *   This function performs lazy initialization of the scheduler's
+ *   high-resolution timer and processes expired timer events. It is intended
+ *   to be invoked periodically from architecture-specific high-resolution
+ *   timer handling code.
+ *
+ * Input Parameters:
+ *   None.
+ *
+ * Returned Value:
+ *   None.
+ *
+ ****************************************************************************/
+
+void nxsched_process_hrtimer(void)
+{
+  uint64_t now = hrtimer_gettime();
+
+  /* Perform one-time initialization */
+
+  if (g_sched_hrtimer_inited == false)
+    {
+      g_sched_hrtimer_inited = true;
+
+      /* Initialize the scheduler hrtimer */
+
+      hrtimer_init(&g_nxsched_hrtimer,
+                   nxsched_hrtimer_callback,
+                   NULL);
+
+      /* Start the first timer event */
+
+      hrtimer_start(&g_nxsched_hrtimer,
+                    now + NSEC_PER_TICK,
+                    HRTIMER_MODE_ABS);
+    }
+
+  /* Process any expired high-resolution timer events */
+
+  hrtimer_process(now);
+}

sched/sched/sched_timerexpiration.c

@@ -424,18 +424,21 @@ static clock_t nxsched_timer_start(clock_t ticks, clock_t interval)
       interval = interval <= (CONFIG_TIMER_ADJUST_USEC / USEC_PER_TICK) ? 0 :
                  interval - (CONFIG_TIMER_ADJUST_USEC / USEC_PER_TICK);
 
-#ifdef CONFIG_SCHED_TICKLESS_ALARM
+#ifdef CONFIG_HRTIMER
+      ret = nxsched_hrtimer_start(interval);
+#else
+#  ifdef CONFIG_SCHED_TICKLESS_ALARM
       /* Convert the delay to a time in the future (with respect
        * to the time when last stopped the timer).
        */
 
       ret = up_alarm_tick_start(ticks + interval);
-#else
+#  else
       /* [Re-]start the interval timer */
 
       ret = up_timer_tick_start(interval);
+#  endif
 #endif
-
       if (ret < 0)
         {
           serr("ERROR: up_timer_start/up_alarm_start failed: %d\n", ret);
@@ -490,7 +493,6 @@ void nxsched_tick_expiration(clock_t ticks)
   /* Process the timer ticks and set up the next interval (or not) */
 
   nexttime = nxsched_timer_process(ticks, elapsed, false);
-
   elapsed = nxsched_timer_start(ticks, nexttime);
   atomic_set(&g_timer_interval, elapsed);
 }
@@ -596,7 +598,6 @@ void nxsched_reassess_timer(void)
   /* Process the timer ticks and start next timer */
 
   nexttime = nxsched_timer_process(ticks, elapsed, true);
-
   elapsed = nxsched_timer_start(ticks, nexttime);
   atomic_set(&g_timer_interval, elapsed);
 }