linux-kernel - Re: [RFC v5 net-next 08/13] mfd: add interface to check whether a device is mfd

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Message-ID: <Ycx+A4KNKiVmH2PJ@google.com>
Date:   Wed, 29 Dec 2021 15:25:55 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Colin Foster <colin.foster@...advantage.com>
Cc:     linux-gpio@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        Russell King <linux@...linux.org.uk>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Andrew Lunn <andrew@...n.ch>, UNGLinuxDriver@...rochip.com,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Vladimir Oltean <vladimir.oltean@....com>
Subject: Re: [RFC v5 net-next 08/13] mfd: add interface to check whether a
 device is mfd

On Sat, 18 Dec 2021, Colin Foster wrote:

> Some drivers will need to create regmaps differently based on whether they
> are a child of an MFD or a standalone device. An example of this would be
> if a regmap were directly memory-mapped or an external bus. In the
> memory-mapped case a call to devm_regmap_init_mmio would return the correct
> regmap. In the case of an MFD, the regmap would need to be requested from
> the parent device.
> 
> This addition allows the driver to correctly reason about these scenarios.
> 
> Signed-off-by: Colin Foster <colin.foster@...advantage.com>
> ---
>  drivers/mfd/mfd-core.c   |  5 +++++
>  include/linux/mfd/core.h | 10 ++++++++++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
> index 684a011a6396..905f508a31b4 100644
> --- a/drivers/mfd/mfd-core.c
> +++ b/drivers/mfd/mfd-core.c
> @@ -33,6 +33,11 @@ static struct device_type mfd_dev_type = {
>  	.name	= "mfd_device",
>  };
>  
> +int device_is_mfd(struct platform_device *pdev)
> +{
> +	return (!strcmp(pdev->dev.type->name, mfd_dev_type.name));
> +}
> +

Why is this device different to any other that has ever been
mainlined?

-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
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