[PATCH v2 13/15] dma-mapping: Add dma_set_max_opt_size()

[John Garry <john.garry@huawei.com>]

Add a function to allow the max size which we want to optimise DMA mappings
for.

Signed-off-by: John Garry <john.garry@huawei.com>
---
 include/linux/dma-map-ops.h |  1 +
 include/linux/dma-mapping.h |  8 ++++++++
 kernel/dma/mapping.c        | 11 +++++++++++
 3 files changed, 20 insertions(+)

diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index 0d53a96a3d64..7f9857da87d8 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -69,6 +69,7 @@ struct dma_map_ops {
 	u64 (*get_required_mask)(struct device *dev);
 	size_t (*max_mapping_size)(struct device *dev);
 	unsigned long (*get_merge_boundary)(struct device *dev);
+	int (*set_max_opt_size)(struct device *dev, size_t size);
 };
 
 #ifdef CONFIG_DMA_OPS
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 183e7103a66d..41681db93580 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -153,6 +153,7 @@ void *dma_vmap_noncontiguous(struct device *dev, size_t size,
 void dma_vunmap_noncontiguous(struct device *dev, void *vaddr);
 int dma_mmap_noncontiguous(struct device *dev, struct vm_area_struct *vma,
 		size_t size, struct sg_table *sgt);
+int dma_set_max_opt_size(struct device *dev, size_t size);
 #else /* CONFIG_HAS_DMA */
 static inline dma_addr_t dma_map_page_attrs(struct device *dev,
 		struct page *page, size_t offset, size_t size,
@@ -266,6 +267,7 @@ static inline unsigned long dma_get_merge_boundary(struct device *dev)
 {
 	return 0;
 }
+
 static inline struct sg_table *dma_alloc_noncontiguous(struct device *dev,
 		size_t size, enum dma_data_direction dir, gfp_t gfp,
 		unsigned long attrs)
@@ -289,6 +291,12 @@ static inline int dma_mmap_noncontiguous(struct device *dev,
 {
 	return -EINVAL;
 }
+
+static inline int dma_set_max_opt_size(struct device *dev, size_t size)
+{
+	return -EINVAL;
+}
+
 #endif /* CONFIG_HAS_DMA */
 
 struct page *dma_alloc_pages(struct device *dev, size_t size,
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 2b06a809d0b9..1e4820b08f7e 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -736,3 +736,14 @@ unsigned long dma_get_merge_boundary(struct device *dev)
 	return ops->get_merge_boundary(dev);
 }
 EXPORT_SYMBOL_GPL(dma_get_merge_boundary);
+
+int dma_set_max_opt_size(struct device *dev, size_t size)
+{
+	const struct dma_map_ops *ops = get_dma_ops(dev);
+
+	if (!ops || !ops->set_max_opt_size)
+		return 0;
+
+	return ops->set_max_opt_size(dev, size);
+}
+EXPORT_SYMBOL_GPL(dma_set_max_opt_size);
-- 
2.26.2