linux-kernel - Re: [PATCH v3 4/6] mm: ioremap: Add arch

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Date:   Fri, 20 May 2022 09:22:24 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
CC:     <catalin.marinas@....com>, <will@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        <hch@...radead.org>, <arnd@...db.de>, <anshuman.khandual@....com>
Subject: Re: [PATCH v3 4/6] mm: ioremap: Add arch_ioremap/iounmap()


On 2022/5/20 2:52, Andrew Morton wrote:
> On Thu, 19 May 2022 16:25:50 +0800 Kefeng Wang <wangkefeng.wang@...wei.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.
>
Oh, forget to add the define part, thanks Andrew.

Hi Catalin, could you help to involve them when taking them, many thanks.

> Otherwise,
>
> Acked-by: Andrew Morton <akpm@...ux-foundation.org>
>
> Please take this patch and [2/6] and [3/6] via the appropriate arm tree.
>
> .