Remove deep sleep lock from wait_ms

API's updated as:
1. wait(float) calls wait_ms for >=0.01s and not in interrupt, else wait_us.

2. wait_ms() is just the thread sleep and doesn't lock hardware sleep.
In order to have backward compatibility, if used in ISR `wait_us` is
called if MBED_TRAP_ERRORS_ENABLED is false

3. wait_us() is a ticker-based wait, always spinning.

platform/mbed_wait_api.h

@@ -55,9 +55,9 @@ extern "C" {
  *  @param s number of seconds to wait
  *
  *  @note
- *    If the RTOS is present, this function always spins to get the exact number of microseconds,
- *    which potentially affects power (such as preventing deep sleep) and multithread performance.
- *    You can avoid it by using ThisThread::sleep_for().
+ *    If the RTOS is present, this function spins to get the exact number of microseconds for
+ *    usec precision upto 10msec. If delay is larger then 10msec and not in ISR, it is same as
+ *    `wait_ms`. `wait_us` and `wait_ms` are recommended over `wait`
  */
 void wait(float s);
 
@@ -66,9 +66,8 @@ void wait(float s);
  *  @param ms the whole number of milliseconds to wait
  *
  *  @note
- *    If the RTOS is present, this function always spins to get the exact number of microseconds,
- *    which potentially affects power (such as preventing deep sleep) and multithread performance.
- *    You can avoid it by using ThisThread::sleep_for().
+ *    If the RTOS is present, it is same as CMSIS osDelay()
+ *    Not callable from interrupts, doesn't lock hardware sleep.
  */
 void wait_ms(int ms);
 
@@ -77,8 +76,9 @@ void wait_ms(int ms);
  *  @param us the whole number of microseconds to wait
  *
  *  @note
- *    If the RTOS is present, this function always spins to get the exact number of microseconds,
- *    which potentially affects power (such as preventing deep sleep) and multithread performance.
+ *    This function always spins to get the exact number of microseconds.
+ *    If RTOS is present, this will affect power (prevents deep sleep) and
+ *    multithread performance, hence spinning for milli-sec wait is not recommended.
  */
 void wait_us(int us);
 

platform/mbed_wait_api_rtos.cpp

@@ -23,21 +23,18 @@
 #include "rtos/rtos.h"
 #include "platform/mbed_critical.h"
 #include "platform/mbed_power_mgmt.h"
+#include "platform/mbed_error.h"
+#include "rtos/ThisThread.h"
 
 void wait(float s)
 {
-    wait_us(s * 1000000.0f);
-}
+    if ((s >= 0.01f)  && core_util_are_interrupts_enabled()) {
+        wait_ms(s * 1000.0f);
+        return;
+    }
 
-void wait_ms(int ms)
-{
-    wait_us(ms * 1000);
-}
-
-void wait_us(int us)
-{
+    uint32_t us = (s * 1000000.0f);
     const ticker_data_t *const ticker = get_us_ticker_data();
-
     uint32_t start = ticker_read(ticker);
     if ((us >= 1000) && core_util_are_interrupts_enabled()) {
         // Use the RTOS to wait for millisecond delays if possible
@@ -50,5 +47,32 @@ void wait_us(int us)
     while ((ticker_read(ticker) - start) < (uint32_t)us);
 }
 
+/*  The actual time delay may be up to one timer tick less - 1 msec */
+void wait_ms(int ms)
+{
+    if (core_util_is_isr_active() || !core_util_are_interrupts_enabled()) {
+#if defined(MBED_TRAP_ERRORS_ENABLED) && MBED_TRAP_ERRORS_ENABLED
+        MBED_ERROR(MBED_MAKE_ERROR(MBED_MODULE_PLATFORM, MBED_ERROR_INVALID_OPERATION),
+                    "Deprecated behavior: milli-sec delay should not be used in interrupt.\n");
+#else
+        wait_us(ms * 1000);
+#endif
+    } else {
+        rtos::ThisThread::sleep_for(ms);
+    }
+}
+
+/*  The actual time delay may be 1 less usec */
+void wait_us(int us)
+{
+    if (us > 10000) {
+        MBED_WARNING(MBED_MAKE_ERROR(MBED_MODULE_PLATFORM, MBED_ERROR_UNKNOWN),
+                     "wait_us blocks deep sleep, wait_ms recommended for long delays\n");
+    }
+    const ticker_data_t *const ticker = get_us_ticker_data();
+    uint32_t start = ticker_read(ticker);
+    while ((ticker_read(ticker) - start) < (uint32_t)us);
+}
+
 #endif // #if MBED_CONF_RTOS_PRESENT