[PATCH 04/10] arm: implement DMA_ATTR_NON_CONSISTENT
Christoph Hellwig
hch at lst.de
Sat Dec 8 17:36:56 UTC 2018
For the iommu ops we can just use the implementaton for DMA coherent
devices. For the regular ops we need mix and match a bit so that
we either use the CMA allocator without remapping, but with a special
error handling case for highmem pages, or the simple allocator.
Signed-off-by: Christoph Hellwig <hch at lst.de>
---
arch/arm/mm/dma-mapping.c | 49 ++++++++++++++++++++++++++++-----------
1 file changed, 35 insertions(+), 14 deletions(-)
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index 2cfb17bad1e6..b3b66b41c450 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -49,6 +49,7 @@ struct arm_dma_alloc_args {
const void *caller;
bool want_vaddr;
int coherent_flag;
+ bool nonconsistent_flag;
};
struct arm_dma_free_args {
@@ -57,6 +58,7 @@ struct arm_dma_free_args {
void *cpu_addr;
struct page *page;
bool want_vaddr;
+ bool nonconsistent_flag;
};
#define NORMAL 0
@@ -348,7 +350,8 @@ static void __dma_free_buffer(struct page *page, size_t size)
static void *__alloc_from_contiguous(struct device *dev, size_t size,
pgprot_t prot, struct page **ret_page,
const void *caller, bool want_vaddr,
- int coherent_flag, gfp_t gfp);
+ int coherent_flag, bool nonconsistent_flag,
+ gfp_t gfp);
static void *__alloc_remap_buffer(struct device *dev, size_t size, gfp_t gfp,
pgprot_t prot, struct page **ret_page,
@@ -405,7 +408,7 @@ static int __init atomic_pool_init(void)
if (dev_get_cma_area(NULL))
ptr = __alloc_from_contiguous(NULL, atomic_pool_size, prot,
&page, atomic_pool_init, true, NORMAL,
- GFP_KERNEL);
+ false, GFP_KERNEL);
else
ptr = __alloc_remap_buffer(NULL, atomic_pool_size, gfp, prot,
&page, atomic_pool_init, true);
@@ -579,7 +582,8 @@ static int __free_from_pool(void *start, size_t size)
static void *__alloc_from_contiguous(struct device *dev, size_t size,
pgprot_t prot, struct page **ret_page,
const void *caller, bool want_vaddr,
- int coherent_flag, gfp_t gfp)
+ int coherent_flag, bool nonconsistent_flag,
+ gfp_t gfp)
{
unsigned long order = get_order(size);
size_t count = size >> PAGE_SHIFT;
@@ -595,12 +599,16 @@ static void *__alloc_from_contiguous(struct device *dev, size_t size,
if (!want_vaddr)
goto out;
+ if (nonconsistent_flag) {
+ if (PageHighMem(page))
+ goto fail;
+ goto out;
+ }
+
if (PageHighMem(page)) {
ptr = __dma_alloc_remap(page, size, GFP_KERNEL, prot, caller);
- if (!ptr) {
- dma_release_from_contiguous(dev, page, count);
- return NULL;
- }
+ if (!ptr)
+ goto fail;
} else {
__dma_remap(page, size, prot);
ptr = page_address(page);
@@ -609,12 +617,15 @@ static void *__alloc_from_contiguous(struct device *dev, size_t size,
out:
*ret_page = page;
return ptr;
+ fail:
+ dma_release_from_contiguous(dev, page, count);
+ return NULL;
}
static void __free_from_contiguous(struct device *dev, struct page *page,
- void *cpu_addr, size_t size, bool want_vaddr)
+ void *cpu_addr, size_t size, bool remapped)
{
- if (want_vaddr) {
+ if (remapped) {
if (PageHighMem(page))
__dma_free_remap(cpu_addr, size);
else
@@ -635,7 +646,11 @@ static void *__alloc_simple_buffer(struct device *dev, size_t size, gfp_t gfp,
struct page **ret_page)
{
struct page *page;
- /* __alloc_simple_buffer is only called when the device is coherent */
+ /*
+ * __alloc_simple_buffer is only called when the device is coherent,
+ * or if the caller explicitly asked for an allocation that is not
+ * consistent.
+ */
page = __dma_alloc_buffer(dev, size, gfp, COHERENT);
if (!page)
return NULL;
@@ -667,13 +682,15 @@ static void *cma_allocator_alloc(struct arm_dma_alloc_args *args,
return __alloc_from_contiguous(args->dev, args->size, args->prot,
ret_page, args->caller,
args->want_vaddr, args->coherent_flag,
+ args->nonconsistent_flag,
args->gfp);
}
static void cma_allocator_free(struct arm_dma_free_args *args)
{
__free_from_contiguous(args->dev, args->page, args->cpu_addr,
- args->size, args->want_vaddr);
+ args->size,
+ args->want_vaddr || args->nonconsistent_flag);
}
static struct arm_dma_allocator cma_allocator = {
@@ -735,6 +752,7 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
.caller = caller,
.want_vaddr = ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) == 0),
.coherent_flag = is_coherent ? COHERENT : NORMAL,
+ .nonconsistent_flag = (attrs & DMA_ATTR_NON_CONSISTENT),
};
#ifdef CONFIG_DMA_API_DEBUG
@@ -773,7 +791,7 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle,
if (cma)
buf->allocator = &cma_allocator;
- else if (is_coherent)
+ else if (is_coherent || (attrs & DMA_ATTR_NON_CONSISTENT))
buf->allocator = &simple_allocator;
else if (allowblock)
buf->allocator = &remap_allocator;
@@ -874,6 +892,7 @@ static void __arm_dma_free(struct device *dev, size_t size, void *cpu_addr,
.cpu_addr = cpu_addr,
.page = page,
.want_vaddr = ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) == 0),
+ .nonconsistent_flag = (attrs & DMA_ATTR_NON_CONSISTENT),
};
buf = arm_dma_buffer_find(cpu_addr);
@@ -1562,7 +1581,8 @@ static void *__arm_iommu_alloc_attrs(struct device *dev, size_t size,
static void *arm_iommu_alloc_attrs(struct device *dev, size_t size,
dma_addr_t *handle, gfp_t gfp, unsigned long attrs)
{
- return __arm_iommu_alloc_attrs(dev, size, handle, gfp, attrs, NORMAL);
+ return __arm_iommu_alloc_attrs(dev, size, handle, gfp, attrs,
+ (attrs & DMA_ATTR_NON_CONSISTENT) ? COHERENT : NORMAL);
}
static void *arm_coherent_iommu_alloc_attrs(struct device *dev, size_t size,
@@ -1650,7 +1670,8 @@ void __arm_iommu_free_attrs(struct device *dev, size_t size, void *cpu_addr,
void arm_iommu_free_attrs(struct device *dev, size_t size,
void *cpu_addr, dma_addr_t handle, unsigned long attrs)
{
- __arm_iommu_free_attrs(dev, size, cpu_addr, handle, attrs, NORMAL);
+ __arm_iommu_free_attrs(dev, size, cpu_addr, handle, attrs,
+ (attrs & DMA_ATTR_NON_CONSISTENT) ? COHERENT : NORMAL);
}
void arm_coherent_iommu_free_attrs(struct device *dev, size_t size,
--
2.19.2
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