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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
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2.9 KiB
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73 lines
2.9 KiB
ReStructuredText
==========================
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Touchscreen Device Drivers
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==========================
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NuttX supports a two-part touchscreen driver architecture.
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#. An "upper half", generic driver that provides the common
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touchscreen interface to application level code, and
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#. A "lower half", platform-specific driver that implements the
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low-level touchscreen controls to implement the touchscreen
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functionality.
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Files supporting the touchscreen controller (TSC) driver can be
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found in the following locations:
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- **Interface Definition**. The header files for NuttX
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touchscreen drivers reside in the
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``include/nuttx/include/input`` directory. The interface
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between the touchscreen controller "upper half" and "lower
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half" drivers are *not* common, but vary from
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controller-to-controller. Because of this, each touchscreen
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driver has its own unique header file that describes the "upper
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half"/"lower half" interface in that directory. The application
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level interface to each touchscreen driver, on the other hand,
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*is* the same for each touchscreen driver and is described
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``include/nuttx/include/input/touchscreen.h``. The touchscreen
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driver uses a standard character driver framework but read
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operations return specially formatted data.
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- **"Upper Half" Driver**. The controller-specific, "upper half"
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touchscreen drivers reside in the directory ``drivers/input``.
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- **"Lower Half" Drivers**. Platform-specific touchscreen drivers
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reside in either: (1) The
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``arch/<architecture>/src/<hardware>`` directory
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for the processor architectures that have build in touchscreen
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controllers or (2) the
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``boards/<arch>/<chip>/<board>/src/``
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directory for boards that use an external touchscreen
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controller chip.
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Application Programming Interface
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=================================
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The first thing to be done in order to use the touchscreen driver from an
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application is to include the correct header filer. It contains the
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Application Programming Interface to the driver. To do so, include
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.. code-block:: c
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#include <nuttx/input/touchscreen.h>
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Touchscreen driver is registered as a POSIX character device file into
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``/dev`` namespace. It is necessary to open the device to get a file descriptor
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for further operations. This can be done with standard POSIX ``open()`` call.
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The driver is accessed through ``read``, ``write``, ``poll`` and ``ioctl``
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interface, Following ``ioctl`` commands are available:
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* :c:macro:`TSIOC_GRAB`
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.. c:macro:: TSIOC_GRAB
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This command let the current handle has the device grabbed. When a handle grabs
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a device it becomes sole recipient for all touchscreen events coming from the
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device. An argument is an ``int32_t`` variable to enable or disable the grab.
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Supported Controllers
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=====================
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Individual touchscreen controller drivers are documented under
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:doc:`input/index`. Controllers currently covered there include:
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- :doc:`input/st7123` — ST7123 (and related ST7121) capacitive multi-touch
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controller over I2C
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