nuttx/Documentation/components/drivers/index.rst

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2020-07-21 00:18:26 +02:00
==============
Device Drivers
==============
NuttX supports a variety of device drivers, which can be broadly
divided in three classes:
.. toctree::
:maxdepth: 1
character/index.rst
block/index.rst
special/index.rst
.. note::
Device driver support depends on the *in-memory*, *pseudo*
file system that is enabled by default.
Lower-half and upper-half
=========================
Drivers in NuttX generally work in two distinct layers:
* An *upper half* which registers itself to NuttX using
a call such as :c:func:`register_driver` or
:c:func:`register_blockdriver` and implements the corresponding
high-level interface (`read`, `write`, `close`, etc.).
implements the interface. This *upper half* calls into
the *lower half* via callbacks.
* A "lower half" which is typically hardware-specific. This is
usually implemented at the architecture or board level.
2020-07-21 00:18:26 +02:00