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The "ni_tio" module contains code to allocate, destroy and operate on a `struct ni_gpct_device`, which represents a number of counters spread over one or more blocks (or "chips"). `struct ni_gpct_device` includes an array member `regs` holding shadow copies of register values. Unfortunately, this is currently shared by each block of counters so they interfere with each other. This is a problem for the "ni_660x" module, which has 8 counters spread over 2 blocks. The `regs` storage needs to be two-dimensional, indexed by block (chip) number and register number. (It does not need to be three-dimensional because the registers for individual counters are intermingled within the block.) Change the `regs` member to an array pointer that can be indexed like a two-dimensional array to access the shadow storage for each register in each block. Allocate the storage in `ni_gpct_device_construct()` and free it in `ni_gpct_device_destroy()`. (`ni_gpct_device_construct()` can determine the number of blocks from the `num_counters` and `counters_per_chip` parameters.) Add new member `num_chips` to hold the number of chips. Use that to check that `chip_index` value is in range in the same places that check the register offset is in range. Remove the `counters_per_chip` member of `struct ni_gpct_device` as it is not needed anywhere and could be easily derived from the `num_counters` and `num_chips` members if required. Thanks to GitHub user "raabej" (real name unknown) for an initial implementation of this in the out-of-tree fork of the Comedi drivers. Signed-off-by: Ian Abbott <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.