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To:     linux-kernel@vger.kernel.org
From:   "Enrico Weigelt, metux IT consult" <metux@gmx.de>
Subject: RFC: build config via DT names
Message-ID: <63f25fea-f163-f9cc-b5b2-f6f291d7f8d2@gmx.de>
Date:   Sat, 10 Feb 2018 16:52:34 +0100
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Hi folks,

I've regularily have the task of configuring a kernel for a given DT.
To make this a little bit easier, I'd like to do this automatically.

The tuff task here is getting a mapping between dt compatible strings
and corresponding CONFIG_* flags. Automatically extracting it from the
source code seems pretty tricky, especially w/ corner cases (eg. some
drivers support groups of devices, depending on config options) - IMHO
it will need some code changes anyways.

Therefore I propose a simple approach using the existing Kconfig system:

Add an extra (toplevel) menu and config flag naming scheme which
directly map DT compatible strings to config flags. For example:

 > fsl,mpc5200-gpio <=> CONFIG_DTDEV_FSL_MPC5200_GPIO

 > config CONFIG_DTDEV_FSL_MPC5200_GPIO
 >    tristate "fsl,mpc5200-gpio"
 >    select GPIO_MPC5200

Note that these flags are separate from the actual drivers - they just
enable them automatically. Of course they'll have to be maintained by
the driver maintainers.


What do you think about this idea ?


--mtx

-- 
Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
info@metux.net -- +49-151-27565287