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Date:   Thu, 19 May 2022 11:52:10 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Kefeng Wang <wangkefeng.wang@huawei.com>
Cc:     <catalin.marinas@arm.com>, <will@kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
        <hch@infradead.org>, <arnd@arndb.de>, <anshuman.khandual@arm.com>
Subject: Re: [PATCH v3 4/6] mm: ioremap: Add arch_ioremap/iounmap()
Message-Id: <20220519115210.a6e41d5a997921354400557e@linux-foundation.org>
In-Reply-To: <20220519082552.117736-5-wangkefeng.wang@huawei.com>
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        <20220519082552.117736-5-wangkefeng.wang@huawei.com>
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On Thu, 19 May 2022 16:25:50 +0800 Kefeng Wang <wangkefeng.wang@huawei.com> wrote:

> Add special hook for architecture to verify or setup addr, size
> or prot when ioremap() or iounmap(), which will make the generic
> ioremap more useful.
> 
>   arch_ioremap() return a pointer,
>     - IS_ERR means return an error
>     - NULL means continue to remap
>     - a non-NULL, non-IS_ERR pointer is directly returned
>   arch_iounmap() return a int value,
>     - 0 means continue to vunmap
>     - error code means skip vunmap and return directly
> 
> ...
>
> --- a/include/asm-generic/io.h
> +++ b/include/asm-generic/io.h
> @@ -964,6 +964,30 @@ static inline void iounmap(volatile void __iomem *addr)
>  #elif defined(CONFIG_GENERIC_IOREMAP)
>  #include <linux/pgtable.h>
>  
> +/*
> + * Arch code can implement the following two special hooks when using GENERIC_IOREMAP
> + * arch_ioremap() return a pointer,
> + *   - IS_ERR means return an error
> + *   - NULL means continue to remap
> + *   - a non-NULL, non-IS_ERR pointer is returned directly
> + * arch_iounmap() return a int,
> + *   - 0 means continue to vunmap
> + *   - error code means skip vunmap and return directly
> + */
> +#ifndef arch_ioremap
> +static inline void __iomem *arch_ioremap(phys_addr_t phys_addr, size_t size, unsigned long prot)
> +{
> +	return NULL;
> +}

Maybe should do

	#define arch_ioremap arch_ioremap

here

> +#endif
> +
> +#ifndef arch_iounmap
> +static inline int arch_iounmap(void __iomem *addr)
> +{
> +	return 0;
> +}

and here.

It shouldn't matter a lot because this file has inclusion guards. 
However it seems tidier and perhaps other code will want to know
whether this was defined.  Dunno.


Otherwise, 

Acked-by: Andrew Morton <akpm@linux-foundation.org>

Please take this patch and [2/6] and [3/6] via the appropriate arm tree.