linux-kernel - Re: [PATCH] fbdev: simplefb: add support for 'memory-region' property on DT node

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Message-id: <2359956.Z9lQWSAgHb@amdc3058>
Date:   Thu, 01 Feb 2018 16:56:08 +0100
From:   Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To:     Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>
Cc:     Hans de Goede <hdegoede@...hat.com>, linux-fbdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>, devicetree@...r.kernel.org
Subject: Re: [PATCH] fbdev: simplefb: add support for 'memory-region'
 property on DT node


Hi,

On Tuesday, January 23, 2018 08:34:56 PM Kunihiko Hayashi wrote:
> Enables 'memory-region' property referring to the memory description on
> the reserved-memory node in case of devicetree use.
> If there is no 'reg' property that specifies the address and size of
> the framebuffer, the address and size written in the memory description
> on the reserved-memory node can be used for the framebuffer.
> 
> Furthermore, the reserved-memory node needs to have "no-map" attributes
> because simplefb driver maps the region by ioremap_wc().
> 
> Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@...ionext.com>

This needs an ACK from Rob or Mark (DT bindings Maintainers).

> ---
>  .../bindings/display/simple-framebuffer.txt        |  3 ++
>  drivers/video/fbdev/simplefb.c                     | 32 ++++++++++++++++++++++
>  2 files changed, 35 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/display/simple-framebuffer.txt b/Documentation/devicetree/bindings/display/simple-framebuffer.txt
> index 5a9ce51..be5139f 100644
> --- a/Documentation/devicetree/bindings/display/simple-framebuffer.txt
> +++ b/Documentation/devicetree/bindings/display/simple-framebuffer.txt
> @@ -56,6 +56,9 @@ Optional properties:
>    framebuffer remains active.
>  
>  - display : phandle pointing to the primary display hardware node
> +- memory-region: phandle to a node describing memory region as framebuffer
> +		 memory instead of reg property. The node should include
> +		 'no-map'.
>  
>  Example:
>  
> diff --git a/drivers/video/fbdev/simplefb.c b/drivers/video/fbdev/simplefb.c
> index a3c44ec..aefc4b1 100644
> --- a/drivers/video/fbdev/simplefb.c
> +++ b/drivers/video/fbdev/simplefb.c
> @@ -29,6 +29,7 @@
>  #include <linux/clk.h>
>  #include <linux/clk-provider.h>
>  #include <linux/of.h>
> +#include <linux/of_address.h>
>  #include <linux/of_platform.h>
>  #include <linux/parser.h>
>  #include <linux/regulator/consumer.h>
> @@ -294,6 +295,35 @@ static void simplefb_clocks_enable(struct simplefb_par *par,
>  static void simplefb_clocks_destroy(struct simplefb_par *par) { }
>  #endif
>  
> +#if defined CONFIG_OF
> +static struct resource *simplefb_parse_dt_reserved_mem(struct device *dev)
> +{
> +	static struct resource res;
> +	struct device_node *np;
> +	int ret;
> +
> +	np = of_parse_phandle(dev->of_node, "memory-region", 0);
> +	if (!np)
> +		return NULL;
> +
> +	ret = of_address_to_resource(np, 0, &res);
> +	if (ret < 0)
> +		return NULL;
> +
> +	if (!of_find_property(np, "no-map", NULL)) {
> +		dev_err(dev, "Can't apply mapped reserved-memory\n");
> +		return NULL;
> +	}
> +
> +	return &res;
> +}
> +#else
> +static struct resource *simplefb_parse_dt_reserved_mem(struct device *dev)
> +{
> +	return NULL;
> +}
> +#endif
> +
>  #if defined CONFIG_OF && defined CONFIG_REGULATOR
>  
>  #define SUPPLY_SUFFIX "-supply"
> @@ -428,6 +458,8 @@ static int simplefb_probe(struct platform_device *pdev)
>  		return ret;
>  
>  	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!mem)
> +		mem = simplefb_parse_dt_reserved_mem(&pdev->dev);
>  	if (!mem) {
>  		dev_err(&pdev->dev, "No memory resource\n");
>  		return -EINVAL;

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics