linux-kernel - Re: [PATCH v2] mfd: syscon: allow to register syscon with a device

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Date:	Wed, 24 Feb 2016 16:00:22 +0100
From:	Arnd Bergmann <arnd@...db.de>
To:	Philipp Zabel <p.zabel@...gutronix.de>
Cc:	Lee Jones <lee.jones@...aro.org>,
	Alexander Shiyan <shc_work@...l.ru>,
	Pankaj Dubey <pankaj.dubey@...sung.com>,
	Pawel Moll <pawel.moll@....com>,
	Wolfram Sang <wsa@...-dreams.de>,
	Peter Seiderer <ps.report@....net>,
	Tushar Behera <tushar.behera@...aro.org>,
	linux-kernel@...r.kernel.org, kernel@...gutronix.de
Subject: Re: [PATCH v2] mfd: syscon: allow to register syscon with a device

On Wednesday 24 February 2016 13:44:24 Philipp Zabel wrote:
> Am Mittwoch, den 24.02.2016, 13:18 +0100 schrieb Arnd Bergmann:
> > On Wednesday 24 February 2016 12:19:01 Philipp Zabel wrote:
> > > Commit bdb0066df96e ("mfd: syscon: Decouple syscon interface from platform
> > > devices") added the possibility to register syscon devices without
> > > associated platform device. This also removed regmap debugfs facilities,
> > > which don't work without a device. Since there is no replacement, this
> > > patch allows again to register syscon regions with an associated device
> > > where that this device exists anyway.
> > > 
> > > Signed-off-by: Philipp Zabel <p.zabel@...gutronix.de>
> > 
> > Can you elaborate how you want to use the new interface?
> 
> I use this patch to attach the regmap to the IOMUXC device, which the
> GPR (syscon) region on i.MX6 is a part of:
> 
> diff --git a/drivers/pinctrl/freescale/pinctrl-imx6q.c b/drivers/pinctrl/freescale/pinctrl-imx6q.c
> index 4d1fcb8..74a68ec 100644
> --- a/drivers/pinctrl/freescale/pinctrl-imx6q.c
> +++ b/drivers/pinctrl/freescale/pinctrl-imx6q.c
> @@ -15,6 +15,7 @@
>  #include <linux/err.h>
>  #include <linux/init.h>
>  #include <linux/io.h>
> +#include <linux/mfd/syscon.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> @@ -473,6 +474,12 @@ static const struct of_device_id imx6q_pinctrl_of_match[] = {
>  
>  static int imx6q_pinctrl_probe(struct platform_device *pdev)
>  {
> +       struct device_node *syscon_np;
> +
> +       syscon_np = of_find_compatible_node(NULL, NULL, "fsl,imx6q-iomuxc-gpr");
> +       if (syscon_np)
> +               syscon_register(&pdev->dev, syscon_np);
> +
>         return imx_pinctrl_probe(pdev, &imx6q_pinctrl_info);
>  }
>  
> The pinctrl driver is probed at arch_initcall time.

I still don't see it where you are getting with this. Is this just for
the debugfs interface or is there something else this does on top of
that?

	Arnd