Convert the 64-bit usec limit to a 32-bit tick limit

arch/arm/src/sam34/Kconfig

@@ -930,7 +930,7 @@ endif # SAM34_GPIO_IRQ
 endmenu # AT91SAM3/4 GPIO Interrupt Configuration
 
 menu "AT91SAM3/4 Timer/Counter Configuration"
-	depends on SAM34_TC
+	depends on SAM34_TC && ARCH_CHIP_SAM4CM
 
 config SAM34_TC0_CLK
 	bool "Enable TC channel 0 clock input pin"
@@ -1058,8 +1058,7 @@ config SAM34_TICKLESS_FREERUN
 		If the Tickless OS feature is enabled, the one clock must be
 		assigned to provided the free-running timer needed by the OS.
 
-endif
-
+endif # SCHED_TICKLESS
 endmenu # AT91SAM3/4 Timer/Counter Configuration
 
 if SAM34_SPI0 || SAM34_SPI1

arch/arm/src/sam34/sam4cm_tickless.c

@@ -231,6 +231,9 @@ static void sam_oneshot_handler(void *arg)
 
 void up_timer_initialize(void)
 {
+#ifdef CONFIG_SCHED_TICKLESS_LIMIT_MAX_SLEEP
+  uint64_t max_delay;
+#endif
   int ret;
 
   /* Initialize the one-shot timer */
@@ -245,12 +248,26 @@ void up_timer_initialize(void)
     }
 
 #ifdef CONFIG_SCHED_TICKLESS_LIMIT_MAX_SLEEP
-  ret = sam_oneshot_max_delay(&g_tickless.oneshot, &g_oneshot_max_delay_usec);
+  /* Get the maximum delay of the one-shot timer in microseconds */
+
+  ret = sam_oneshot_max_delay(&g_tickless.oneshot, &max_delay);
   if (ret < 0)
     {
       tclldbg("ERROR: sam_oneshot_max_delay failed\n");
       PANIC();
     }
+
+  /* Convert this to configured clock ticks for use by the OS timer logic */
+
+  max_delay /= CONFIG_USEC_PER_TICK;
+  if (max_delay > UINT32_MAX)
+    {
+      g_oneshot_maxticks = UINT32_MAX
+    }
+  else
+    {
+      g_oneshot_maxticks = max_delay;
+    }
 #endif
 
   /* Initialize the free-running timer */

include/nuttx/arch.h

@@ -119,32 +119,36 @@ typedef CODE void (*phy_enable_t)(bool enable);
  * Public Variables
  ****************************************************************************/
 
+#undef EXTERN
+#if defined(__cplusplus)
+#define EXTERN extern "C"
+extern "C"
+{
+#else
+#define EXTERN extern
+#endif
+
 #ifdef CONFIG_SCHED_TICKLESS_LIMIT_MAX_SLEEP
 /* By default, the RTOS tickless logic assumes that range of times that can
  * be represented by the underlying hardware time is so large that no special
  * precautions need to taken.  That is not always the case.  If there is a
  * limit to the maximum timing interval that be represented by the timer,
  * then that limit must be respected.
  *
- * If CONFIG_SCHED_TICKLESS_LIMIT_MAX_SLEEP is defined, then a 64-bit global
- * variable called g_oneshot_max_delay_usec variable is enabled. The variable
+ * If CONFIG_SCHED_TICKLESS_LIMIT_MAX_SLEEP is defined, then use a 32-bit
+ * global variable called g_oneshot_maxticks variable is enabled. This variable
  * is initialized by platform-specific logic at runtime to the maximum delay
- * that the timer can wait (in microseconds).  The RTOS tickless logic will
- * then limit all requested delays to this value (in ticks).
+ * that the timer can wait (in configured clock ticks).  The RTOS tickless
+ * logic will then limit all requested delays to this value (in ticks).
  */
 
-extern uint64_t g_oneshot_max_delay_usec;
+EXTERN uint32_t g_oneshot_maxticks;
 #endif
 
 /****************************************************************************
  * Public Function Prototypes
  ****************************************************************************/
 
-#ifdef __cplusplus
-extern "C"
-{
-#endif
-
 /****************************************************************************
  * These are standard interfaces that must be exported to the base RTOS
  * logic from architecture-specific code.
@@ -1946,6 +1950,7 @@ int up_getc(void);
 
 void up_puts(FAR const char *str);
 
+#undef EXTERN
 #ifdef __cplusplus
 }
 #endif

sched/Kconfig

@@ -85,10 +85,11 @@ config SCHED_TICKLESS_LIMIT_MAX_SLEEP
 	bool "Max sleep period (in microseconds)"
 	default n
 	---help---
-		Enables g_oneshot_max_delay_usec variable. The variable is
+		Enables use of the g_oneshot_maxticks variable. This variable is
 		initialized by platform-specific logic at runtime to the maximum
-		delay that the timer can wait (in microseconds).  The RTOS tickless
-		logic will then limit all requested delays to this value (in ticks).
+		delay that the timer can wait (in configured clock ticks).  The
+		RTOS tickless logic will then limit all requested delays to this
+		value.
 
 endif
 

sched/sched/sched_timerexpiration.c

@@ -94,14 +94,14 @@
  * limit to the maximum timing interval that be represented by the timer,
  * then that limit must be respected.
  *
- * If CONFIG_SCHED_TICKLESS_LIMIT_MAX_SLEEP is defined, then a 64-bit global
- * variable called g_oneshot_max_delay_usec variable is enabled. The variable
+ * If CONFIG_SCHED_TICKLESS_LIMIT_MAX_SLEEP is defined, then a 32-bit global
+ * variable called g_oneshot_maxticks variable is enabled. The variable
  * is initialized by platform-specific logic at runtime to the maximum delay
  * that the timer can wait (in microseconds).  The RTOS tickless logic will
  * then limit all requested delays to this value (in ticks).
  */
 
-uint64_t g_oneshot_max_delay_usec;
+uint32_t g_oneshot_maxticks = UINT32_MAX;
 #endif
 
 /************************************************************************
@@ -445,9 +445,9 @@ static void sched_timer_start(unsigned int ticks)
       struct timespec ts;
 
 #if CONFIG_SCHED_TICKLESS_LIMIT_MAX_SLEEP
-      if (ticks > (g_oneshot_max_delay_usec / CONFIG_USEC_PER_TICK))
+      if (ticks > g_oneshot_maxticks)
         {
-          ticks = (g_oneshot_max_delay_usec / CONFIG_USEC_PER_TICK);
+          ticks = g_oneshot_maxticks;
         }
 #endif