[PATCH v6 1/2] dma/contiguous: Add helper to test reserved memory type

[Maxime Ripard <mripard@kernel.org>]

A given reserved-memory region can be of multiple types.

We have currently four types defined in the tree: contiguous, backed by
CMA, coherent and swiotlb, backed by their respective allocators, and a
platform-specific one for tegra.

However, some users, like dma-buf heaps, might be interested in the
exact type of a reserved memory region they are getting. It would thus
be useful to have helpers to test if a given region is of a given type.

Since we only care about CMA for now though, let's create one for CMA
only.

Signed-off-by: Maxime Ripard <mripard@kernel.org>
---
 include/linux/dma-map-ops.h | 13 +++++++++++++
 kernel/dma/contiguous.c     |  7 +++++++
 2 files changed, 20 insertions(+)

diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index f48e5fb88bd5dd346094bbf2ce1b79e5f5bfe1a6..ea646acb6367bd062619b337013db221749f85ab 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -153,10 +153,23 @@ static inline void dma_free_contiguous(struct device *dev, struct page *page,
 {
 	__free_pages(page, get_order(size));
 }
 #endif /* CONFIG_DMA_CMA*/
 
+#if defined(CONFIG_DMA_CMA) && defined(CONFIG_OF_RESERVED_MEM)
+struct reserved_mem;
+
+bool of_reserved_mem_is_contiguous(const struct reserved_mem *rmem);
+#else
+struct reserved_mem;
+
+static inline bool of_reserved_mem_is_contiguous(const struct reserved_mem *rmem)
+{
+	return false;
+}
+#endif
+
 #ifdef CONFIG_DMA_DECLARE_COHERENT
 int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
 		dma_addr_t device_addr, size_t size);
 void dma_release_coherent_memory(struct device *dev);
 int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size,
diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
index 8df0dfaaca18eeb0a20145512ba64425d2e7601e..ace4982e928e404315cf38551e1596f7ed445156 100644
--- a/kernel/dma/contiguous.c
+++ b/kernel/dma/contiguous.c
@@ -493,6 +493,13 @@ static int __init rmem_cma_setup(struct reserved_mem *rmem)
 		&rmem->base, (unsigned long)rmem->size / SZ_1M);
 
 	return 0;
 }
 RESERVEDMEM_OF_DECLARE(cma, "shared-dma-pool", rmem_cma_setup);
+
+bool of_reserved_mem_is_contiguous(const struct reserved_mem *rmem)
+{
+	return rmem->ops == &rmem_cma_ops;
+}
+EXPORT_SYMBOL_GPL(of_reserved_mem_is_contiguous);
+
 #endif

-- 
2.50.0