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On the ADLink PCI-7230, digital input channels 0 and 1 can be used as external interrupt sources. A rising edge on each input latches a corresponding local interrupt input of the PCI interface chip. Writing a "clear IRQ" register clears both latches. Add a new Comedi subdevice for each interrupt source, supporting the asynchronous command interface. This writes the state of the 16 digital inputs to the subdevice's data buffer each time the corresponding interrupt occurs. This could be adapted to support the PCI-7233, PCI-7432 and PCI-7433 boards too. They all have two interrupt sources, although for PCI-7233 each interrupt source is triggered by a change of state of 16 digital inputs (0-15 and 16-31). The "clear IRQ" register is at a different offset for some boards. Signed-off-by: Bernd Harries <bha@gmx.de> Signed-off-by: Ian Abbott <abbotti@mev.co.uk> Link: https://lore.kernel.org/r/20210118141829.376505-1-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.