Re: [PATCH v4 01/17] mfd: madera: Add register definitions for Cirrus Logic Madera codecs

Lee Jones
2017-08-08T11:03:25Z

On Fri, 28 Jul 2017, Richard Fitzgerald wrote:

> This patch adds a header file of register definitions for Cirrus
> Logic "Madera" class codecs. These codecs are all based off a common
> set of hardware IP so have a common register map (with a few minor
> device-to-device variations).
>
> The registers.h file is tool-generated directly from the hardware design
> but has been manually stripped down to reduce size (full register
> map is >44000 lines). All names are kept the same as datasheet names
> so that they can be cross-referenced between source and datasheet without
> confusion.
>
> The register map layout is kept fully-defined rather than factored into
> macros and/or block-indexing code. The major reasons for this are:
>
> - #1 is that it makes the source highly greppable, which is important.
> "What does the driver do with register bits XYZ" or "Where does it use
> register bits XYZ" are commonly types of questions. These can be quickly
> answered by a grep. Squashing definitions into generator macros or block-
> indexing code is a way of defeating grep.
>
> - most of the register definitions are used in tables, so a constant value
> is required. Using generator macros make the table definition clunky and
> obscure.
>
> - the code is clearer when it's there in the source exactly what register
> and field it is using
>
> - it is easier to diff the register map of a new (unsupported) codec against
> what is already supported and merge in differences
>
> - it makes the register map available in source for maintenance/debugging
> instead of having to refer back to the datasheet for a register map
>
> Signed-off-by: Richard Fitzgerald <rf@opensource.wolfsonmicro.com>
> ---
> Changes since V3:
> - Manually stripped out a lot more stuff, defines we're not using right now
> - Added the explanation above to the commit message of why we define the
> map effectively verbatim
>
> MAINTAINERS | 10 +
> include/linux/mfd/madera/registers.h | 3987 ++++++++++++++++++++++++++++++++++
> 2 files changed, 3997 insertions(+)
> create mode 100644 include/linux/mfd/madera/registers.h

For my own reference:
Acked-for-MFD-by: Lee Jones <lee.jones@linaro.org>

--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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