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SubjectRe: [PATCH v2 3/5] mm: ioremap: Add arch_ioremap/iounmap()
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On 2022/5/19 12:46, Anshuman Khandual wrote:
> Hi Kefeng,
>
> On 4/29/22 16:02, Kefeng Wang wrote:
>> Add special hook for architecture to verify addr, size and prot
>> or setup when ioremap() or iounmap(), which will make the generic
>> ioremap more useful.
>>
>> arch_ioremap() return a 'void __iomem *',
>> - 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
> Should not these comments be also included as in-code documentation, possibly
> near generic fall back stubs for arch_ioremap()/arch_iounmap() in the header
> include/asm-generic/io.h ?
Ok, I will add some document in io.h
>
>> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
>> ---
>> include/asm-generic/io.h | 14 ++++++++++++++
>> mm/ioremap.c | 14 +++++++++++++-
>> 2 files changed, 27 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
>> index e6ffa2519f08..f2f9aeedb5e8 100644
>> --- a/include/asm-generic/io.h
>> +++ b/arch_iounmap
>> @@ -964,6 +964,20 @@ static inline void iounmap(volatile void __iomem *addr)
>> #elif defined(CONFIG_GENERIC_IOREMAP)
>> #include <linux/pgtable.h>
>>
>> +#ifndef arch_ioremap
>> +static inline void __iomem *arch_ioremap(phys_addr_t phys_addr, size_t size, unsigned long prot)
>> +{
>> + return NULL;
>> +}
>> +#endif
>> +
>> +#ifndef arch_iounmap
>> +static inline int arch_iounmap(void __iomem *addr)
>> +{
>> + return 0;
>> +}
>> +#endif
> There is a function in arch/arm/ with exact same name although the platform does
> not enable GENERIC_IOREMAP. That function would require renaming for these arch
> callbacks to be added here in GENERIC_IOREMAP path. Otherwise, it might be just
> confusing later.
>
> git grep "arch_iounmap" arch/arm/
>
> arch/arm/include/asm/io.h:extern void (*arch_iounmap)(volatile void __iomem *);
> arch/arm/mm/ioremap.c:void (*arch_iounmap)(volatile void __iomem *) = __iounmap;
> arch/arm/mm/ioremap.c: arch_iounmap(cookie);
> arch/arm/mm/nommu.c:void (*arch_iounmap)(volatile void __iomem *);

After

  59d3ae9a5bf60 ("ARM: remove Intel iop33x and iop13xx support") v5.4
  3e3f354bc383a ("ARM: remove ebsa110 platform") v5.11

arch_iounmap is useless, we could directly kill arch_iounmap/__iounmap
on arm,

will add new cleanup patch in v3.


>
>> +
>> void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size, unsigned long prot);
>> void iounmap(volatile void __iomem *addr);
>>
>> diff --git a/mm/ioremap.c b/mm/ioremap.c
>> index 7cb9996b0c12..de5a2e899e14 100644
>> --- a/mm/ioremap.c
>> +++ b/mm/ioremap.c
>> @@ -16,6 +16,7 @@ void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size, unsigned long pro
>> unsigned long offset, vaddr;
>> phys_addr_t last_addr;
>> struct vm_struct *area;
>> + void __iomem *base;
>>
>> /* Disallow wrap-around or zero size */
>> last_addr = phys_addr + size - 1;
>> @@ -27,6 +28,12 @@ void __iomem *ioremap_prot(phys_addr_t phys_addr, size_t size, unsigned long pro
>> phys_addr -= offset;
>> size = PAGE_ALIGN(size + offset);
>>
>> + base = arch_ioremap(phys_addr, size, prot);
>> + if (IS_ERR(base))
>> + return NULL;
>> + else if (base)
>> + return base;
>> +
>> area = get_vm_area_caller(size, VM_IOREMAP,
>> __builtin_return_address(0));
>> if (!area)
>> @@ -45,6 +52,11 @@ EXPORT_SYMBOL(ioremap_prot);
>>
>> void iounmap(volatile void __iomem *addr)
>> {
>> - vunmap((void *)((unsigned long)addr & PAGE_MASK));
>> + void *vaddr = (void *)((unsigned long)addr & PAGE_MASK);
> Should not this variable be 'void __iomem *vaddr' instead, like above in
> ioremap_prot(). Because arch_iounmap() takes 'void __iomem *' instead.

Will do, thanks.

>> +
>> + if (arch_iounmap(vaddr))
>> + return;
>> +
>> + vunmap(vaddr);
>> }
>> EXPORT_SYMBOL(iounmap);
> - Anshuman
> .

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