linux-kernel - Re: [PATCH v6 3/7] mfd: Add support for the Lantiq PEF2256 framer

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Message-ID: <20230420123946.GB996918@google.com>
Date:   Thu, 20 Apr 2023 13:39:46 +0100
From:   Lee Jones <lee@...nel.org>
To:     Herve Codina <herve.codina@...tlin.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, alsa-devel@...a-project.org,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v6 3/7] mfd: Add support for the Lantiq PEF2256 framer

On Mon, 17 Apr 2023, Herve Codina wrote:

> The Lantiq PEF2256 is a framer and line interface component designed to
> fulfill all required interfacing between an analog E1/T1/J1 line and the
> digital PCM system highway/H.100 bus.
> 
> Signed-off-by: Herve Codina <herve.codina@...tlin.com>
> ---
>  drivers/mfd/Kconfig         |  16 +
>  drivers/mfd/Makefile        |   1 +
>  drivers/mfd/pef2256-regs.h  | 250 ++++++++++
>  drivers/mfd/pef2256.c       | 950 ++++++++++++++++++++++++++++++++++++

95% of this driver needs to be moved somewhere else.

What is a Framer?  Perhaps sound/ is a good candidate?

>  include/linux/mfd/pef2256.h |  52 ++
>  5 files changed, 1269 insertions(+)
>  create mode 100644 drivers/mfd/pef2256-regs.h
>  create mode 100644 drivers/mfd/pef2256.c
>  create mode 100644 include/linux/mfd/pef2256.h

[...]

> +static int pef2256_add_audio_devices(struct pef2256 *pef2256)
> +{
> +	const char *compatible = "lantiq,pef2256-codec";
> +	struct mfd_cell *audio_devs;
> +	struct device_node *np;
> +	unsigned int count = 0;
> +	unsigned int i;
> +	int ret;
> +
> +	for_each_available_child_of_node(pef2256->dev->of_node, np) {
> +		if (of_device_is_compatible(np, compatible))
> +			count++;
> +	}

Converting Device Tree nodes into MFD cells to register with the
Platform Device API is not a reasonable use-case of MFD.

Have the CODEC driver match on "lantiq,pef2256-codec" and let it
instantiate itself.

Your first version using of_platform_populate() was closer to the mark.

> +	if (!count)
> +		return 0;
> +
> +	audio_devs = kcalloc(count, sizeof(*audio_devs), GFP_KERNEL);
> +	if (!audio_devs)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < count; i++) {
> +		(audio_devs + i)->name = "lantiq-pef2256-codec";
> +		(audio_devs + i)->of_compatible = compatible;
> +		(audio_devs + i)->id = i;
> +	}
> +
> +	ret = mfd_add_devices(pef2256->dev, 0, audio_devs, count, NULL, 0, NULL);
> +	kfree(audio_devs);
> +	return ret;
> +}

-- 
Lee Jones [李琼斯]