Mostly intended to ease experimentation, no particular plans for APIs
so far (far less their stability), is_preempt_thread() provided is
mostly an example.

Required for the testsuite.

So, now it's possible to just do normal Python's "import time".

The integration with Zephyr is fairly clean but as MicroPython Hardware API
requires pin ID to be a single value, but Zephyr operates GPIO in terms of
ports and pins, not just pins, a "hierarchical" ID is required, using tuple
of (port, pin). Port is a string, effectively a device name of a GPIO port,
per Zephyr conventions these are "GPIO_0", "GPIO_1", etc.; pin is integer
number of pin with the port (supposed to be in range 0-31).

Example of pin initialization:

pin = Pin(("GPIO_1", 21), Pin.OUT)

(an LED on FRDM-K64F's Port B, Pin 21).

There is support for in/out pins and pull up/pull down but currently
there is no interrupt support.

Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@linaro.org>
Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>

This patch modifies the HW macro definition in order to let micropython
report correctly the BOARD and the SOC on which it is working on.

This provides time and sleep together with the usual ticks_us/_ms/_diff
and sleep_us/ms family.

We also provide access to Zephyr's high precision timer as ticks_cpu().

Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>

The boot issue text mentions a help() function and encourages
the user to run it. It is very disconcerting to find that the
function does not exist...

Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>