From: catalin.marinas@arm•com (Catalin Marinas)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCHv6 3/5] common: dma-mapping: Introduce common remapping functions
Date: Mon, 11 Aug 2014 19:05:42 +0100 [thread overview]
Message-ID: <20140811180542.GI13871@arm.com> (raw)
In-Reply-To: <53E55C86.3040705@codeaurora.org>
On Sat, Aug 09, 2014 at 12:25:58AM +0100, Laura Abbott wrote:
> On 8/8/2014 3:45 PM, Andrew Morton wrote:
> > On Fri, 8 Aug 2014 13:23:15 -0700 Laura Abbott <lauraa@codeaurora•org> wrote:
> >> For architectures without coherent DMA, memory for DMA may
> >> need to be remapped with coherent attributes. Factor out
> >> the the remapping code from arm and put it in a
> >> common location to reduce code duplication.
> >>
> >> As part of this, the arm APIs are now migrated away from
> >> ioremap_page_range to the common APIs which use map_vm_area for remapping.
> >> This should be an equivalent change and using map_vm_area is more
> >> correct as ioremap_page_range is intended to bring in io addresses
> >> into the cpu space and not regular kernel managed memory.
> >>
> >> ...
> >>
> >> @@ -267,3 +269,68 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
> >> return ret;
> >> }
> >> EXPORT_SYMBOL(dma_common_mmap);
> >> +
> >> +/*
> >> + * remaps an allocated contiguous region into another vm_area.
> >> + * Cannot be used in non-sleeping contexts
> >> + */
> >> +
> >> +void *dma_common_contiguous_remap(struct page *page, size_t size,
> >> + unsigned long vm_flags,
> >> + pgprot_t prot, const void *caller)
> >> +{
> >> + int i;
> >> + struct page **pages;
> >> + void *ptr;
> >> +
> >> + pages = kmalloc(sizeof(struct page *) << get_order(size), GFP_KERNEL);
> >> + if (!pages)
> >> + return NULL;
> >> +
> >> + for (i = 0; i < (size >> PAGE_SHIFT); i++)
> >> + pages[i] = page + i;
> >
> > Assumes a single mem_map[] array. That's not the case for sparsemem
> > (at least).
>
> Good point. I guess the best option is to increment via pfn and call
> pfn_to_page. Either that or go back to slightly abusing
> ioremap_page_range to remap normal memory.
I now noticed you suggested the pfn_to_page(). I think this should work
and it's better than ioremap_page_range().
--
Catalin
next prev parent reply other threads:[~2014-08-11 18:05 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-08 20:23 [PATCHv6 1/5] lib/genalloc.c: Add power aligned algorithm Laura Abbott
2014-08-08 20:23 ` [PATCHv6 2/5] lib/genalloc.c: Add genpool range check function Laura Abbott
2014-08-08 22:40 ` Andrew Morton
2014-08-08 20:23 ` [PATCHv6 3/5] common: dma-mapping: Introduce common remapping functions Laura Abbott
2014-08-08 22:45 ` Andrew Morton
2014-08-08 23:25 ` Laura Abbott
2014-08-11 18:05 ` Catalin Marinas [this message]
2014-08-11 18:04 ` Catalin Marinas
2014-08-08 20:23 ` [PATCHv6 4/5] arm: use genalloc for the atomic pool Laura Abbott
2014-08-08 20:23 ` [PATCHv6 5/5] arm64: Add atomic pool for non-coherent and CMA allocations Laura Abbott
2014-08-08 22:36 ` [PATCHv6 1/5] lib/genalloc.c: Add power aligned algorithm Andrew Morton
2014-08-08 22:41 ` Laura Abbott
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