linux-kernel - Re: [RFC PATCH v2 04/12] mtd: rawnand: ams-delta: request data port GPIO resource

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Date:   Tue, 7 Aug 2018 19:00:22 +0200
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Janusz Krzysztofik <jmkrzyszt@...il.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Jonathan Corbet <corbet@....net>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Tony Lindgren <tony@...mide.com>,
        Aaro Koskinen <aaro.koskinen@....fi>,
        linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org,
        linux-mtd@...ts.infradead.org, linux-doc@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v2 04/12] mtd: rawnand: ams-delta: request data port
 GPIO resource

On Tue,  7 Aug 2018 00:29:10 +0200
Janusz Krzysztofik <jmkrzyszt@...il.com> wrote:

> Data port used by the driver is actually an OMAP MPUIO device, already
> under control of gpio-omap driver.  For that reason we used to not
> request the memory region of the port as that would fail because the
> region is already busy.  Despite that, we are still accessing the port
> by just ioremapping it and performing read/write operations.  Moreover,
> we are doing that without any proteciton from other users legally
> manipulating the port pins over GPIO API.
> 
> The plan is to convert the driver to access the port over functions
> exposed by the gpio-omap driver.  Before that happens, already prevent
> from other users accessing the port pins by requesting an array of its
> GPIO descriptors.
> 
> Signed-off-by: Janusz Krzysztofik <jmkrzyszt@...il.com>

Reviewed-by: Boris Brezillon <boris.brezillon@...tlin.com>

> ---
>  drivers/mtd/nand/raw/ams-delta.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/mtd/nand/raw/ams-delta.c b/drivers/mtd/nand/raw/ams-delta.c
> index 48233d638d2a..09d6901fc94d 100644
> --- a/drivers/mtd/nand/raw/ams-delta.c
> +++ b/drivers/mtd/nand/raw/ams-delta.c
> @@ -161,6 +161,7 @@ static int ams_delta_init(struct platform_device *pdev)
>  	struct mtd_info *mtd;
>  	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	void __iomem *io_base;
> +	struct gpio_descs *data_gpiods;
>  	int err = 0;
>  
>  	if (!res)
> @@ -261,6 +262,13 @@ static int ams_delta_init(struct platform_device *pdev)
>  		dev_err(&pdev->dev, "CLE GPIO request failed (%d)\n", err);
>  		goto out_mtd;
>  	}
> +	/* Request array of data pins, initialize them as input */
> +	data_gpiods = devm_gpiod_get_array(&pdev->dev, "data", GPIOD_IN);
> +	if (IS_ERR(data_gpiods)) {
> +		err = PTR_ERR(data_gpiods);
> +		dev_err(&pdev->dev, "data GPIO request failed: %d\n", err);
> +		goto out_mtd;
> +	}
>  
>  	/* Scan to find existence of the device */
>  	err = nand_scan(mtd, 1);