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[v2,2/7] DMA-API: Introduce dma_(un)map_resource

Message ID 1431973504-5903-3-git-send-email-wdavis@nvidia.com
State Not Applicable
Headers show

Commit Message

wdavis@nvidia.com May 18, 2015, 6:24 p.m. UTC 
From: Will Davis <wdavis@nvidia.com>

Add functions to DMA-map and -unmap a resource for a given device. This
will allow devices to DMA-map a peer device's resource (for example,
another device's BAR region on PCI) to enable peer-to-peer transactions.

Signed-off-by: Will Davis <wdavis@nvidia.com>
Reviewed-by: Terence Ripperda <tripperda@nvidia.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
---
 include/asm-generic/dma-mapping-broken.h |  9 +++++++++
 include/asm-generic/dma-mapping-common.h | 34 ++++++++++++++++++++++++++++++++
 include/linux/dma-mapping.h              |  7 +++++++
 3 files changed, 50 insertions(+)

Comments

Joerg Roedel May 29, 2015, 8:16 a.m. UTC | #1 
On Mon, May 18, 2015 at 01:24:59PM -0500, wdavis@nvidia.com wrote:
> +static inline dma_addr_t dma_map_resource_attrs(struct device *dev,
> +						struct resource *res,
> +						size_t offset, size_t size,
> +						enum dma_data_direction dir,
> +						struct dma_attrs *attrs)
> +{
> +	const struct dma_map_ops *ops = get_dma_ops(dev);
> +	dma_addr_t addr = 0;
> +
> +	BUG_ON(!valid_dma_direction(dir));
> +	if (ops->map_resource)
> +		addr = ops->map_resource(dev, res, offset, size, dir,
		> atops->map_resourcetrs);
> +	debug_dma_map_resource(dev, res, offset, size, dir, addr);
> +
> +	return addr;
> +}

Please just do a BUG_ON(ops->map_resource == NULL) instead of checking the
pointer and returning 0 if it is NULL. The 0 could be a valid dma_addr
in some implementations, drivers are supposed to check the returned addr
with dma_mapping_error only (and no '== 0' checks).


	Joerg

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diff mbox

Patch

diff --git a/include/asm-generic/dma-mapping-broken.h b/include/asm-generic/dma-mapping-broken.h
index 6c32af9..d171f01 100644
--- a/include/asm-generic/dma-mapping-broken.h
+++ b/include/asm-generic/dma-mapping-broken.h
@@ -59,6 +59,15 @@  extern void
 dma_unmap_page(struct device *dev, dma_addr_t dma_address, size_t size,
 	       enum dma_data_direction direction);
 
+extern dma_addr_t
+dma_map_resource(struct device *dev, struct resource *res,
+		 unsigned long offset, size_t size,
+		 enum dma_data_direction direction);
+
+extern void
+dma_unmap_resource(struct device *dev, dma_addr_t dma_address, size_t size,
+		   enum dma_data_direction direction);
+
 extern void
 dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle, size_t size,
 			enum dma_data_direction direction);
diff --git a/include/asm-generic/dma-mapping-common.h b/include/asm-generic/dma-mapping-common.h
index 940d5ec..cd9948d 100644
--- a/include/asm-generic/dma-mapping-common.h
+++ b/include/asm-generic/dma-mapping-common.h
@@ -73,6 +73,36 @@  static inline void dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg
 		ops->unmap_sg(dev, sg, nents, dir, attrs);
 }
 
+static inline dma_addr_t dma_map_resource_attrs(struct device *dev,
+						struct resource *res,
+						size_t offset, size_t size,
+						enum dma_data_direction dir,
+						struct dma_attrs *attrs)
+{
+	const struct dma_map_ops *ops = get_dma_ops(dev);
+	dma_addr_t addr = 0;
+
+	BUG_ON(!valid_dma_direction(dir));
+	if (ops->map_resource)
+		addr = ops->map_resource(dev, res, offset, size, dir, attrs);
+	debug_dma_map_resource(dev, res, offset, size, dir, addr);
+
+	return addr;
+}
+
+static inline void dma_unmap_resource_attrs(struct device *dev, dma_addr_t addr,
+					    size_t size,
+					    enum dma_data_direction dir,
+					    struct dma_attrs *attrs)
+{
+	const struct dma_map_ops *ops = get_dma_ops(dev);
+
+	BUG_ON(!valid_dma_direction(dir));
+	if (ops->unmap_resource)
+		ops->unmap_resource(dev, addr, size, dir, attrs);
+	debug_dma_unmap_resource(dev, addr, size, dir);
+}
+
 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)
@@ -180,6 +210,10 @@  dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
 #define dma_unmap_single(d, a, s, r) dma_unmap_single_attrs(d, a, s, r, NULL)
 #define dma_map_sg(d, s, n, r) dma_map_sg_attrs(d, s, n, r, NULL)
 #define dma_unmap_sg(d, s, n, r) dma_unmap_sg_attrs(d, s, n, r, NULL)
+#define dma_map_resource(d, e, o, s, r) \
+	dma_map_resource_attrs(d, e, o, s, r, NULL)
+#define dma_unmap_resource(d, a, s, r) \
+	dma_unmap_resource_attrs(d, a, s, r, NULL)
 
 extern int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
 			   void *cpu_addr, dma_addr_t dma_addr, size_t size);
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index ac07ff0..05b0b51 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -34,6 +34,13 @@  struct dma_map_ops {
 	void (*unmap_page)(struct device *dev, dma_addr_t dma_handle,
 			   size_t size, enum dma_data_direction dir,
 			   struct dma_attrs *attrs);
+	dma_addr_t (*map_resource)(struct device *dev, struct resource *res,
+				   unsigned long offset, size_t size,
+				   enum dma_data_direction dir,
+				   struct dma_attrs *attrs);
+	void (*unmap_resource)(struct device *dev, dma_addr_t dma_handle,
+			       size_t size, enum dma_data_direction dir,
+			       struct dma_attrs *attrs);
 	/*
 	 * map_sg returns 0 on error and a value > 0 on success.
 	 * It should never return a value < 0.