current_usec() returns a uint64_t, but it used TICK2USEC(timebase)
to convert scheduler ticks to microseconds. On 32-bit clock_t builds,
TICK2USEC() performs the multiplication in 32-bit arithmetic before the
result is widened.
With CONFIG_USEC_PER_TICK=10000, this wraps after about 71.6 minutes:
UINT32_MAX / 1000000 ~= 4294 seconds
After the wrap, up_timer_gettick() can report time near zero again. This
can leave absolute watchdog timeouts, such as those used by usleep() /
clock_nanosleep(), waiting for a tick value that will not be reached until
the 32-bit scheduler counter wraps.
Cast timebase to uint64_t before multiplying by USEC_PER_TICK so
current_usec() remains monotonic across the 32-bit microsecond boundary.
Signed-off-by: Max Kriegleder <max.kriegleder@gmail.com>
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