sched/sched: enable OS tickless mode support using hrtimer

Add support for running the OS in tickless mode with hrtimer, allowing
the scheduler to operate without periodic ticks while maintaining
high-resolution timer functionality.

Signed-off-by: Chengdong Wang <wangchengdong@lixiang.com>

sched/sched/sched.h

@@ -309,6 +309,10 @@ extern volatile spinlock_t g_cpu_tasklistlock;
 
 void nxsched_process_tick(void);
 
+#if defined(CONFIG_HRTIMER) && defined(CONFIG_SCHED_TICKLESS)
+int nxsched_hrtimer_tick_start(clock_t tick);
+#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_timer.c

@@ -108,6 +108,16 @@ nxsched_hrtimer_callback(FAR const struct hrtimer_s *hrtimer,
  * Public Functions
  ****************************************************************************/
 
+#if defined(CONFIG_HRTIMER) && defined(CONFIG_SCHED_TICKLESS)
+int nxsched_hrtimer_tick_start(clock_t tick)
+{
+  return hrtimer_start(&g_sched_hrtimer,
+                       nxsched_hrtimer_callback,
+                       tick * NSEC_PER_TICK,
+                       HRTIMER_MODE_ABS);
+}
+#endif
+
 /****************************************************************************
  * Name: nxsched_process_timer
  *

sched/wdog/wdog.h

@@ -114,12 +114,16 @@ static inline_function clock_t wd_adjust_next_tick(clock_t tick)
 static inline_function void wd_timer_start(clock_t tick)
 {
   clock_t next_tick = wd_adjust_next_tick(tick);
-#ifdef CONFIG_SCHED_TICKLESS_ALARM
+
+#ifdef CONFIG_HRTIMER
+  nxsched_hrtimer_tick_start(tick);
+#elif defined(CONFIG_SCHED_TICKLESS_ALARM)
   up_alarm_tick_start(next_tick);
 #else
   up_timer_tick_start(next_tick - clock_systime_ticks());
 #endif
 }
+
 static inline_function void wd_timer_cancel(void)
 {
   struct timespec ts;