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arm: dma: Allow CMA pages to not have a kernel mapping

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Currently, there are use cases where not having any kernel
mapping is required; if the CMA memory needs to be used as
a pool which can have both cached and uncached mappings we
need to remove the mapping to avoid the multiple mapping
problem. Extend the dma APIs to use the DMA_ATTR_NO_KERNEL_MAPPING
with CMA. This doesn't end up saving any virtual address space
but the mapping will still not be present.

Change-Id: I64d21250abbe615c43e2b5b1272ee2b6d106705a
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>
Signed-off-by: Vijayanand Jitta <vjitta@codeaurora.org>
Signed-off-by: Charan Teja Reddy <charante@codeaurora.org>
Signed-off-by: Qingqing Zhou <qqzhou@codeaurora.org>
This commit is contained in:
Patrick Daly 2016-02-17 15:58:22 -08:00 • committed by Gerrit - the friendly Code Review server
commit 0b06cd5ca5
1 changed files with 21 additions and 13 deletions
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34
arch/arm/mm/dma-mapping.c
View file

@ -484,12 +484,26 @@ static int __dma_update_pte(pte_t *pte, unsigned long addr, void *data)
return 0;
}
static void __dma_remap(struct page *page, size_t size, pgprot_t prot)
static int __dma_clear_pte(pte_t *pte, unsigned long addr, void *data)
{
pte_clear(&init_mm, addr, pte);
return 0;
}
static void __dma_remap(struct page *page, size_t size, pgprot_t prot,
bool want_vaddr)
{
unsigned long start = (unsigned long) page_address(page);
unsigned end = start + size;
int (*func)(pte_t *pte, unsigned long addr, void *data);
apply_to_page_range(&init_mm, start, size, __dma_update_pte, &prot);
if (!want_vaddr)
func = __dma_clear_pte;
else
func = __dma_update_pte;
apply_to_page_range(&init_mm, start, size, func, &prot);
mb(); /*Ensure pte's are updated */
flush_tlb_kernel_range(start, end);
}
@ -572,9 +586,6 @@ static void *__alloc_from_contiguous(struct device *dev, size_t size,
__dma_clear_buffer(page, size, coherent_flag);
if (!want_vaddr)
goto out;
if (PageHighMem(page)) {
ptr = dma_common_contiguous_remap(page, size, prot, caller);
if (!ptr) {
@ -582,11 +593,10 @@ static void *__alloc_from_contiguous(struct device *dev, size_t size,
return NULL;
}
} else {
__dma_remap(page, size, prot);
__dma_remap(page, size, prot, want_vaddr);
ptr = page_address(page);
}
out:
*ret_page = page;
return ptr;
}
@ -594,12 +604,10 @@ static void *__alloc_from_contiguous(struct device *dev, size_t size,
static void __free_from_contiguous(struct device *dev, struct page *page,
void *cpu_addr, size_t size, bool want_vaddr)
{
if (want_vaddr) {
if (PageHighMem(page))
dma_common_free_remap(cpu_addr, size);
else
__dma_remap(page, size, PAGE_KERNEL);
}
if (PageHighMem(page))
dma_common_free_remap(cpu_addr, size);
else
__dma_remap(page, size, PAGE_KERNEL, true);
dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT);
}