nuttx/Documentation/os/drivers/special/usbdev.rst
Vinicius May f6ecf80ebb Documentation: brand new layout for NuttX documentation.
The documentation grew one page at a time, so the tree follows the
history of who wrote what and not the shape of NuttX. Scheduling is
spread over three places, a driver page can sit above the subsystem
that owns it, and the front page lists everything at the same level.
That is a lot to face when all you want to know is where the scheduler
lives.

This change files every page under the code it describes. It is a move,
not a rewrite: outside the ten pages named below, every page keeps the
text that is already in master, and no page's text is deleted.

What it does:

* Groups the table of contents into nine chapters.
* Moves the OS subsystems under os/: scheduling, memory, drivers,
  filesystem, networking, IPC, interrupts, libs, time.
* Renames the platform pages to the names the source tree uses, and
  derives their tags from the tree instead of by hand.
* Splits guides/ by subject.
* Adds Documentation/redirects.py, with a rule for every page that left
  its old path, so old URLs keep working. The redirect page also carries
  a link's #anchor across to the new page.

Ten pages have text that is new or rewritten. Nine of them are the
landing page of a chapter, which has to exist for the new structure:

    index                  the front page
    os/index               OS Design
    os/scheduling/index    Scheduling
    os/interrupts/index    Interrupts
    os/ipc/index           IPC
    os/time/index          Time and timers
    about/index            About
    developing/index       Developing NuttX
    ReleaseNotes/index     Release notes

The tenth is os/libs/libbuiltin, the only page here with technical
content: libs/libbuiltin/ had no page at all. Five SVG diagrams come
with these pages, hand-written XML with no editor metadata.

Nothing outside Documentation/ is touched.

How it was checked:

* Sphinx builds with -W: no warnings, and no document left outside a
  toctree.
* A script, offered in the PR, proves the narrow claim this rests on.
  For every page outside the ten named above it erases what a move
  touches -- link target, path, tag line, toctree block, table border --
  from the whole old text and the whole new text, and requires the two
  to be byte for byte identical. It also requires every sentence of a
  deleted page to turn up somewhere, and every page that left its old
  path to have a redirect, from a URL that existed, to where its content
  went. It exits non-zero and names the page if any of that is not true,
  and it tests added pages too, so forgetting to declare one cannot make
  it pass.
* An independent audit checked 133 factual claims on these ten pages
  against the tree, one shell command per claim: 130 confirmed, 1
  refuted and fixed here, 2 not checkable.
* tools/checkpatch.sh is clean over the range.

The diff is large because moving a page changes every link that points
to it. Most of it is pure renames, and board pages that gained one tag
line.

Assisted-by: Claude:claude-opus-5
2026-10-08 01:40:54 +08:00

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=======================
USB Device-Side Drivers
=======================
- ``include/nuttx/usb/usbdev.h``. All structures and APIs
needed to work with USB device-side drivers are provided in
this header file.
- ``include/nuttx/usb/usbdev_trace.h``. Declarations needed
to work with the NuttX USB device driver trace capability. That
USB trace capability is detailed in :ref:`separate
document <usbtrace>`.
- ``struct usbdev_s``. Each USB device controller driver must
implement an instance of ``struct usbdev_s``. This structure is
defined in ``include/nuttx/usb/usbdev.h``.
**Examples**: ``arch/arm/src/dm320/dm320_usbdev.c``,
``arch/arm/src/lpc17xx_40xx/lpc17_40_usbdev.c``,
``arch/arm/src/lpc214x/lpc214x_usbdev.c``,
``arch/arm/src/lpc313x/lpc313x_usbdev.c``, and
``arch/arm/src/common/stm32/stm32_usbdev_m3m4_v1.c``.
- ``struct usbdevclass_driver_s``. Each USB device class
driver must implement an instance of
``struct usbdevclass_driver_s``. This structure is also defined
in ``include/nuttx/usb/usbdev.h``.
**Examples**: ``drivers/usbdev/pl2303.c`` and
``drivers/usbdev/usbmsc.c``
- **Binding USB Device-Side Drivers**. USB device-side controller
drivers are not normally directly accessed by user code, but
are usually bound to another, higher level USB device class
driver. The class driver is then configured to export the USB
device functionality. In general, the binding sequence is:
#. Each USB device class driver includes an initialization
entry point that is called from the application at
initialization time.
**Examples**: The function ``usbdev_serialinitialize()`` in
the file ``drivers/usbdev/pl2303.c`` and the function
in the file ``drivers/usbdev/usbmsc.c``
#. These initialization functions called the driver API,
``usbdev_register()``. This driver function will *bind* the
USB class driver to the USB device controller driver,
completing the initialization.