linux-kernel - Re: [PATCH v2 1/2] power: reset: at91: add sama5d3 reset function

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Message-ID: <20150720093343.GF15539@piout.net>
Date:	Mon, 20 Jul 2015 11:33:43 +0200
From:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:	Josh Wu <josh.wu@...el.com>
Cc:	Nicolas Ferre <nicolas.ferre@...el.com>,
	linux-arm-kernel@...ts.infradead.org,
	Guenter Roeck <linux@...ck-us.net>,
	Kumar Gala <galak@...eaurora.org>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Rob Herring <robh+dt@...nel.org>,
	Sebastian Reichel <sre@...nel.org>,
	Ben Dooks <ben.dooks@...ethink.co.uk>,
	Krzysztof Kozlowski <k.kozlowski.k@...il.com>,
	Pawel Moll <pawel.moll@....com>, devicetree@...r.kernel.org,
	linux-pm@...r.kernel.org, Sudeep Holla <sudeep.holla@....com>,
	Wei Yongjun <yongjun_wei@...ndmicro.com.cn>,
	Fabian Frederick <fabf@...net.be>,
	linux-kernel@...r.kernel.org,
	Boris Brezillon <boris.brezillon@...e-electrons.com>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	Mark Rutland <mark.rutland@....com>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>
Subject: Re: [PATCH v2 1/2] power: reset: at91: add sama5d3 reset function

On 20/07/2015 at 17:32:05 +0800, Josh Wu wrote :
> This patch introduces a new compatible string: "atmel,sama5d3-rstc" and
> new reset function for sama5d3 and later chips.
> 
> As in sama5d3 or later chips, we don't have to shutdown the DDR
> controller before reset. Shutdown the DDR controller before reset is a
> workaround to avoid DDR signal driving the bus, but since sama5d3 and
> later chips there is no such a conflict.
> 
> So in this patch:
>    1. the sama5d3 reset function only need to write the rstc register
> and return.
>    2. we can remove the code related with sama5d3 DDR controller as
> we don't use it at all.
> 
> Signed-off-by: Josh Wu <josh.wu@...el.com>
> Acked-by: Nicolas Ferre <nicolas.ferre@...el.com>
Acked-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>

> ---
> 
> Changes in v2:
> - aligned the function parameters to be consist with the coding style
> - refined the commit log
> - add binding document changes
> - use of_device_is_compitable() instead
> 
>  .../devicetree/bindings/arm/atmel-at91.txt         |  2 +-
>  drivers/power/reset/at91-reset.c                   | 26 ++++++++++++++++------
>  2 files changed, 20 insertions(+), 8 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/arm/atmel-at91.txt b/Documentation/devicetree/bindings/arm/atmel-at91.txt
> index 424ac8c..dd998b9 100644
> --- a/Documentation/devicetree/bindings/arm/atmel-at91.txt
> +++ b/Documentation/devicetree/bindings/arm/atmel-at91.txt
> @@ -87,7 +87,7 @@ One interrupt per TC channel in a TC block:
>  
>  RSTC Reset Controller required properties:
>  - compatible: Should be "atmel,<chip>-rstc".
> -  <chip> can be "at91sam9260" or "at91sam9g45"
> +  <chip> can be "at91sam9260" or "at91sam9g45" or "sama5d3"
>  - reg: Should contain registers location and length
>  
>  Example:
> diff --git a/drivers/power/reset/at91-reset.c b/drivers/power/reset/at91-reset.c
> index 36dc52f..c378d4e 100644
> --- a/drivers/power/reset/at91-reset.c
> +++ b/drivers/power/reset/at91-reset.c
> @@ -123,6 +123,15 @@ static int at91sam9g45_restart(struct notifier_block *this, unsigned long mode,
>  	return NOTIFY_DONE;
>  }
>  
> +static int sama5d3_restart(struct notifier_block *this, unsigned long mode,
> +			   void *cmd)
> +{
> +	writel(cpu_to_le32(AT91_RSTC_KEY | AT91_RSTC_PERRST | AT91_RSTC_PROCRST),
> +	       at91_rstc_base);
> +
> +	return NOTIFY_DONE;
> +}
> +
>  static void __init at91_reset_status(struct platform_device *pdev)
>  {
>  	u32 reg = readl(at91_rstc_base + AT91_RSTC_SR);
> @@ -155,13 +164,13 @@ static void __init at91_reset_status(struct platform_device *pdev)
>  static const struct of_device_id at91_ramc_of_match[] = {
>  	{ .compatible = "atmel,at91sam9260-sdramc", },
>  	{ .compatible = "atmel,at91sam9g45-ddramc", },
> -	{ .compatible = "atmel,sama5d3-ddramc", },
>  	{ /* sentinel */ }
>  };
>  
>  static const struct of_device_id at91_reset_of_match[] = {
>  	{ .compatible = "atmel,at91sam9260-rstc", .data = at91sam9260_restart },
>  	{ .compatible = "atmel,at91sam9g45-rstc", .data = at91sam9g45_restart },
> +	{ .compatible = "atmel,sama5d3-rstc", .data = sama5d3_restart },
>  	{ /* sentinel */ }
>  };
>  
> @@ -181,13 +190,16 @@ static int at91_reset_of_probe(struct platform_device *pdev)
>  		return -ENODEV;
>  	}
>  
> -	for_each_matching_node(np, at91_ramc_of_match) {
> -		at91_ramc_base[idx] = of_iomap(np, 0);
> -		if (!at91_ramc_base[idx]) {
> -			dev_err(&pdev->dev, "Could not map ram controller address\n");
> -			return -ENODEV;
> +	if (!of_device_is_compatible(pdev->dev.of_node, "atmel,sama5d3-rstc")) {
> +		/* we need to shutdown the ddr controller, so get ramc base */
> +		for_each_matching_node(np, at91_ramc_of_match) {
> +			at91_ramc_base[idx] = of_iomap(np, 0);
> +			if (!at91_ramc_base[idx]) {
> +				dev_err(&pdev->dev, "Could not map ram controller address\n");
> +				return -ENODEV;
> +			}
> +			idx++;
>  		}
> -		idx++;
>  	}
>  
>  	match = of_match_node(at91_reset_of_match, pdev->dev.of_node);
> -- 
> 1.9.1
> 

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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