Hardware I2C implementations must provide a .init() protocol method if they
want to support reconfiguration.  Otherwise the default is that i2c.init()
raises an OSError (currently the case for all ports).

mp_machine_soft_i2c_locals_dict is renamed to mp_machine_i2c_locals_dict to
match the generic SPI bindings.

Fixes issue #6623 (where calling .init() on a HW I2C would crash).

Signed-off-by: Damien George <damien@micropython.org>

With a warning that this way of constructing software I2C/SPI is
deprecated.  The check and warning will be removed in a future release.

This should help existing code to migrate to the new SoftI2C/SoftSPI types.

Signed-off-by: Damien George <damien@micropython.org>

Previous commits removed the ability for one I2C/SPI constructor to
construct both software- or hardware-based peripheral instances.  Such
construction is now split to explicit soft and non-soft types.

This commit makes both types available in all ports that previously could
create both software and hardware peripherals: machine.I2C and machine.SPI
construct hardware instances, while machine.SoftI2C and machine.SoftSPI
create software instances.

This is a breaking change for use of software-based I2C and SPI.  Code that
constructed I2C/SPI peripherals in the following way will need to be
changed:

    machine.I2C(-1, ...)            ->  machine.SoftI2C(...)
    machine.I2C(scl=scl, sda=sda)   ->  machine.SoftI2C(scl=scl, sda=sda)

    machine.SPI(-1, ...)            ->  machine.SoftSPI(...)
    machine.SPI(sck=sck, mosi=mosi, miso=miso)
                        ->  machine.SoftSPI(sck=sck, mosi=mosi, miso=miso)

Code which uses machine.I2C and machine.SPI classes to access hardware
peripherals does not need to change.

Signed-off-by: Damien George <damien@micropython.org>

Also rename machine_i2c_type to mp_machine_soft_i2c_type.  These changes
make it clear that it's a soft-I2C implementation, and match SoftSPI.

Signed-off-by: Damien George <damien@micropython.org>

The mpconfigport.h file is an internal header and should only ever be
included once by mpconfig.h.

Signed-off-by: Damien George <damien@micropython.org>

This commit adds time.ticks_ms/us support using RTC1 as the timebase.  It
also adds the time.ticks_add/diff helper functions.  This feature can be
enabled using MICROPY_PY_TIME_TICKS.  If disabled the system uses the
legacy sleep methods and does not have any ticks functions.

In addition support for MICROPY_EVENT_POLL_HOOK was added to the
time.sleep_ms(x) function, making this function more power efficient and
allows support for select.poll/asyncio.  To support this, the RTC's CCR0
was used to schedule a ~1msec event to wakeup the CPU.

Some important notes about the RTC timebase:

- Since the granularity of RTC1's ticks are approx 30usec, time.ticks_us is
not perfect, does not have 1us resolution, but is otherwise quite usable.
For tighter measurments the ticker's 1MHz counter should be used.

- time.ticks_ms(x) should *not* be called in an IRQ with higher prio than
the RTC overflow irq (3).  If so it introduces a race condition and
possibly leads to wrong tick calculations.

See #6171 and #6202.

Commit 6cea369b89b2223cf07ff8768e50dc39bbb770fe updated the TinyUSB
submodule to a version based on nrfx v2.0.0.  This commit updates the nrf
port to work with the latest TinyUSB and nrfx v2.0.0.

The "random" module no longer uses the hardware RNG (the extmod version of
this module has a pseudo-random number generator), so the config option
MICROPY_PY_RANDOM_HW_RNG is no longer meaningful.  This commit replaces it
with MICROPY_HW_ENABLE_RNG, which controls whether the hardware RNG is
included in the build.