linux-kernel - Re: [PATCH 3/5] nvmem: mtk-efuse: fix different address space warnings of sparse

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Date:   Thu, 21 Sep 2017 00:19:57 +0800
From:   Sean Wang <sean.wang@...iatek.com>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
CC:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Jassi Brar <jaswinder.singh@...aro.org>,
        Keiji Hayashibara <hayashibara.keiji@...ionext.com>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 3/5] nvmem: mtk-efuse: fix different address space
 warnings of sparse

On Mon, 2017-09-11 at 22:01 +0900, Masahiro Yamada wrote:
> Fix the following sparse warnings:
> 
> drivers/nvmem/mtk-efuse.c:24:30: warning: incorrect type in initializer (different address spaces)
> drivers/nvmem/mtk-efuse.c:24:30:    expected void [noderef] <asn:2>*base
> drivers/nvmem/mtk-efuse.c:24:30:    got void *context
> drivers/nvmem/mtk-efuse.c:37:30: warning: incorrect type in initializer (different address spaces)
> drivers/nvmem/mtk-efuse.c:37:30:    expected void [noderef] <asn:2>*base
> drivers/nvmem/mtk-efuse.c:37:30:    got void *context
> drivers/nvmem/mtk-efuse.c:69:23: warning: incorrect type in assignment (different address spaces)
> drivers/nvmem/mtk-efuse.c:69:23:    expected void *priv
> drivers/nvmem/mtk-efuse.c:69:23:    got void [noderef] <asn:2>*[assigned] base
> 
> The type of nvmem_config->priv is (void *), so sparse complains
> about assignment of the base address with (void __iomem *) type.
> 
> Even if we cast it out, sparse still warns:
> warning: cast removes address space of expression
> 
> Of course, we can shut up the sparse by marking __force, but a more
> correct way is to put the base address into driver private data.
> 
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>

Acked-by: Sean Wang <sean.wang@...iatek.com>

> ---
> 
>  drivers/nvmem/mtk-efuse.c | 26 +++++++++++++++++---------
>  1 file changed, 17 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/nvmem/mtk-efuse.c b/drivers/nvmem/mtk-efuse.c
> index fa7a0f6..c4058b5 100644
> --- a/drivers/nvmem/mtk-efuse.c
> +++ b/drivers/nvmem/mtk-efuse.c
> @@ -18,15 +18,19 @@
>  #include <linux/nvmem-provider.h>
>  #include <linux/platform_device.h>
>  
> +struct mtk_efuse_priv {
> +	void __iomem *base;
> +};
> +
>  static int mtk_reg_read(void *context,
>  			unsigned int reg, void *_val, size_t bytes)
>  {
> -	void __iomem *base = context;
> +	struct mtk_efuse_priv *priv = context;
>  	u32 *val = _val;
>  	int i = 0, words = bytes / 4;
>  
>  	while (words--)
> -		*val++ = readl(base + reg + (i++ * 4));
> +		*val++ = readl(priv->base + reg + (i++ * 4));
>  
>  	return 0;
>  }
> @@ -34,12 +38,12 @@ static int mtk_reg_read(void *context,
>  static int mtk_reg_write(void *context,
>  			 unsigned int reg, void *_val, size_t bytes)
>  {
> -	void __iomem *base = context;
> +	struct mtk_efuse_priv *priv = context;
>  	u32 *val = _val;
>  	int i = 0, words = bytes / 4;
>  
>  	while (words--)
> -		writel(*val++, base + reg + (i++ * 4));
> +		writel(*val++, priv->base + reg + (i++ * 4));
>  
>  	return 0;
>  }
> @@ -50,19 +54,23 @@ static int mtk_efuse_probe(struct platform_device *pdev)
>  	struct resource *res;
>  	struct nvmem_device *nvmem;
>  	struct nvmem_config econfig = {};
> -	void __iomem *base;
> +	struct mtk_efuse_priv *priv;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
>  
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	base = devm_ioremap_resource(dev, res);
> -	if (IS_ERR(base))
> -		return PTR_ERR(base);
> +	priv->base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(priv->base))
> +		return PTR_ERR(priv->base);
>  
>  	econfig.stride = 4;
>  	econfig.word_size = 4;
>  	econfig.reg_read = mtk_reg_read;
>  	econfig.reg_write = mtk_reg_write;
>  	econfig.size = resource_size(res);
> -	econfig.priv = base;
> +	econfig.priv = priv;
>  	econfig.dev = dev;
>  	econfig.owner = THIS_MODULE;
>  	nvmem = nvmem_register(&econfig);