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Subject[RFC PATCH 3/7] dma-mapping: allow archs to optionally specify a ->map_pfn() operation
From
Date
This is in support of enabling block device drivers to perform DMA
to/from persistent memory which may not have a backing struct page
entry.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
arch/Kconfig | 3 +++
include/asm-generic/dma-mapping-common.h | 30 ++++++++++++++++++++++++++++++
include/linux/dma-debug.h | 23 +++++++++++++++++++----
include/linux/dma-mapping.h | 8 +++++++-
lib/dma-debug.c | 4 ++--
5 files changed, 61 insertions(+), 7 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 05d7a8a458d5..80ea3e124494 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -203,6 +203,9 @@ config HAVE_DMA_ATTRS
config HAVE_DMA_CONTIGUOUS
bool

+config HAVE_DMA_PFN
+ bool
+
config GENERIC_SMP_IDLE_THREAD
bool

diff --git a/include/asm-generic/dma-mapping-common.h b/include/asm-generic/dma-mapping-common.h
index 3378dcf4c31e..58fad817e51a 100644
--- a/include/asm-generic/dma-mapping-common.h
+++ b/include/asm-generic/dma-mapping-common.h
@@ -17,9 +17,15 @@ static inline dma_addr_t dma_map_single_attrs(struct device *dev, void *ptr,

kmemcheck_mark_initialized(ptr, size);
BUG_ON(!valid_dma_direction(dir));
+#ifdef CONFIG_HAVE_DMA_PFN
+ addr = ops->map_pfn(dev, page_to_pfn_typed(virt_to_page(ptr)),
+ (unsigned long)ptr & ~PAGE_MASK, size,
+ dir, attrs);
+#else
addr = ops->map_page(dev, virt_to_page(ptr),
(unsigned long)ptr & ~PAGE_MASK, size,
dir, attrs);
+#endif
debug_dma_map_page(dev, virt_to_page(ptr),
(unsigned long)ptr & ~PAGE_MASK, size,
dir, addr, true);
@@ -68,6 +74,29 @@ static inline void dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg
ops->unmap_sg(dev, sg, nents, dir, attrs);
}

+#ifdef CONFIG_HAVE_DMA_PFN
+static inline dma_addr_t dma_map_pfn(struct device *dev, __pfn_t pfn,
+ size_t offset, size_t size,
+ enum dma_data_direction dir)
+{
+ struct dma_map_ops *ops = get_dma_ops(dev);
+ dma_addr_t addr;
+
+ BUG_ON(!valid_dma_direction(dir));
+ addr = ops->map_pfn(dev, pfn, offset, size, dir, NULL);
+ debug_dma_map_pfn(dev, pfn, offset, size, dir, addr, false);
+
+ return addr;
+}
+
+static inline dma_addr_t dma_map_page(struct device *dev, struct page *page,
+ size_t offset, size_t size,
+ enum dma_data_direction dir)
+{
+ kmemcheck_mark_initialized(page_address(page) + offset, size);
+ return dma_map_pfn(dev, page_to_pfn_typed(page), offset, size, dir);
+}
+#else
static inline dma_addr_t dma_map_page(struct device *dev, struct page *page,
size_t offset, size_t size,
enum dma_data_direction dir)
@@ -82,6 +111,7 @@ static inline dma_addr_t dma_map_page(struct device *dev, struct page *page,

return addr;
}
+#endif /* CONFIG_HAVE_DMA_PFN */

static inline void dma_unmap_page(struct device *dev, dma_addr_t addr,
size_t size, enum dma_data_direction dir)
diff --git a/include/linux/dma-debug.h b/include/linux/dma-debug.h
index fe8cb610deac..eb3e69c61e5e 100644
--- a/include/linux/dma-debug.h
+++ b/include/linux/dma-debug.h
@@ -34,10 +34,18 @@ extern void dma_debug_init(u32 num_entries);

extern int dma_debug_resize_entries(u32 num_entries);

-extern void debug_dma_map_page(struct device *dev, struct page *page,
- size_t offset, size_t size,
- int direction, dma_addr_t dma_addr,
- bool map_single);
+extern void debug_dma_map_pfn(struct device *dev, __pfn_t pfn, size_t offset,
+ size_t size, int direction, dma_addr_t dma_addr,
+ bool map_single);
+
+static inline void debug_dma_map_page(struct device *dev, struct page *page,
+ size_t offset, size_t size,
+ int direction, dma_addr_t dma_addr,
+ bool map_single)
+{
+ return debug_dma_map_pfn(dev, page_to_pfn_typed(page), offset, size,
+ direction, dma_addr, map_single);
+}

extern void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr);

@@ -109,6 +117,13 @@ static inline void debug_dma_map_page(struct device *dev, struct page *page,
{
}

+static inline void debug_dma_map_pfn(struct device *dev, __pfn_t pfn,
+ size_t offset, size_t size,
+ int direction, dma_addr_t dma_addr,
+ bool map_single)
+{
+}
+
static inline void debug_dma_mapping_error(struct device *dev,
dma_addr_t dma_addr)
{
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index c3007cb4bfa6..6411621e4179 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -26,11 +26,17 @@ struct dma_map_ops {

int (*get_sgtable)(struct device *dev, struct sg_table *sgt, void *,
dma_addr_t, size_t, struct dma_attrs *attrs);
-
+#ifdef CONFIG_HAVE_DMA_PFN
+ dma_addr_t (*map_pfn)(struct device *dev, __pfn_t pfn,
+ unsigned long offset, size_t size,
+ enum dma_data_direction dir,
+ struct dma_attrs *attrs);
+#else
dma_addr_t (*map_page)(struct device *dev, struct page *page,
unsigned long offset, size_t size,
enum dma_data_direction dir,
struct dma_attrs *attrs);
+#endif
void (*unmap_page)(struct device *dev, dma_addr_t dma_handle,
size_t size, enum dma_data_direction dir,
struct dma_attrs *attrs);
diff --git a/lib/dma-debug.c b/lib/dma-debug.c
index 9722bd2dbc9b..a447730fff97 100644
--- a/lib/dma-debug.c
+++ b/lib/dma-debug.c
@@ -1250,7 +1250,7 @@ out:
put_hash_bucket(bucket, &flags);
}

-void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,
+void debug_dma_map_pfn(struct device *dev, __pfn_t pfn, size_t offset,
size_t size, int direction, dma_addr_t dma_addr,
bool map_single)
{
@@ -1268,7 +1268,7 @@ void debug_dma_map_page(struct device *dev, struct page *page, size_t offset,

entry->dev = dev;
entry->type = dma_debug_page;
- entry->pfn = page_to_pfn(page);
+ entry->pfn = pfn.pfn;
entry->offset = offset,
entry->dev_addr = dma_addr;
entry->size = size;


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