lp_us_tickers test - provide counter overflow protection

Since according to the ticker requirements min acceptable counter size is 12 bits (low power timer) for which max count is 4095, then all test cases must be executed in this time window.
HAL ticker layer handles overflow and it is not handled in the target ticker drivers.

TESTS/mbed_hal/lp_us_tickers/main.cpp

@@ -26,7 +26,7 @@
 #endif
 
 #define FORCE_OVERFLOW_TEST (false)
-#define TICKER_INT_VAL 2000
+#define TICKER_INT_VAL 500
 #define TICKER_DELTA 50
 
 #define LP_TICKER_OVERFLOW_DELTA 0 // this will allow to detect that ticker counter rollovers to 0
@@ -51,9 +51,6 @@ unsigned int ticker_overflow_delta;
  * Parameter <step> is used to disable compiler optimisation. */
 uint32_t count_ticks(volatile uint32_t cycles, uint32_t step)
 {
-    /* Init the ticker. */
-    intf->init();
-
     core_util_critical_section_enter();
 
     const uint32_t start = intf->read();
@@ -133,9 +130,7 @@ void ticker_info_test(void)
 /* Test that ticker interrupt fires only when the ticker counter increments to the value set by ticker_set_interrupt. */
 void ticker_interrupt_test(void)
 {
-    uint32_t ticker_timeout[] = { 100, 500, 1000, 2000 };
-
-    intf->init();
+    uint32_t ticker_timeout[] = { 100, 200, 300, 500 };
 
     for (uint32_t i = 0; i < (sizeof(ticker_timeout) / sizeof(uint32_t)); i++) {
         intFlag = 0;
@@ -175,8 +170,6 @@ void ticker_past_test(void)
 {
     intFlag = 0;
 
-    intf->init();
-
     const uint32_t tick_count = intf->read();
 
     /* Set interrupt tick count to value in the past.
@@ -193,8 +186,6 @@ void ticker_repeat_reschedule_test(void)
 {
     intFlag = 0;
 
-    intf->init();
-
     const uint32_t tick_count = intf->read();
 
     /* Set interrupt. Interrupt should be fired when tick count is equal to:
@@ -227,8 +218,6 @@ void ticker_fire_now_test(void)
 {
     intFlag = 0;
 
-    intf->init();
-
     intf->fire_interrupt();
 
     /* On some platforms set_interrupt function sets interrupt in the nearest feature. */
@@ -256,8 +245,6 @@ void ticker_overflow_test(void)
 
     intFlag = 0;
 
-    intf->init();
-
     /* Wait for max count. */
     while (intf->read() != (max_count - ticker_overflow_delta)) {
         /* Just wait. */
@@ -296,8 +283,6 @@ void ticker_overflow_test(void)
 /* Test that the ticker increments by one on each tick. */
 void ticker_increment_test(void)
 {
-    intf->init();
-
     const ticker_info_t* p_ticker_info = intf->get_info();
 
     /* Perform test based on ticker speed. */
@@ -334,8 +319,6 @@ void ticker_speed_test(void)
     Timer timer;
     int counter = NUM_OF_CALLS;
 
-    intf->init();
-
     /* ---- Test ticker_read function. ---- */
     timer.reset();
     timer.start();
@@ -391,15 +374,38 @@ void ticker_speed_test(void)
     TEST_ASSERT(timer.read_us() < (NUM_OF_CALLS * (MAX_FUNC_EXEC_TIME_US + DELTA_FUNC_EXEC_TIME_US)));
 }
 
+/* Since according to the ticker requirements min acceptable counter size is
+ * 12 bits (low power timer)  for which max count is
+ * 4095, then all test cases must be executed in this time window.
+ * HAL ticker layer handles overflow and it is not handled in the target
+ * ticker drivers.
+ */
+void overflow_protect()
+{
+    const uint32_t ticks_now = intf->read();
+    const ticker_info_t* p_ticker_info = intf->get_info();
+
+    const uint32_t max_count = (1 << p_ticker_info->bits - 1);
+
+    if ((max_count - ticks_now) > 4000) {
+        return;
+    }
+
+    while (intf->read() > ticks_now);
+}
 
 utest::v1::status_t hf_ticker_setup(const Case *const source, const size_t index_of_case)
 {
     intf = get_us_ticker_data()->interface;
 
+    intf->init();
+
     set_us_ticker_irq_handler(ticker_event_handler_stub);
 
     ticker_overflow_delta = HF_TICKER_OVERFLOW_DELTA;
 
+    overflow_protect();
+
     return greentea_case_setup_handler(source, index_of_case);
 }
 
@@ -408,10 +414,14 @@ utest::v1::status_t lp_ticker_setup(const Case *const source, const size_t index
 {
     intf = get_lp_ticker_data()->interface;
 
+    intf->init();
+
     set_lp_ticker_irq_handler(ticker_event_handler_stub);
 
     ticker_overflow_delta = LP_TICKER_OVERFLOW_DELTA;
 
+    overflow_protect();
+
     return greentea_case_setup_handler(source, index_of_case);
 }
 #endif