[RFC PATCH v2 03/10] dma: contiguous: Add API to check if an allocation is from CMA

[Samiullah Khawaja <skhawaja@google.com>]

Add an API that uses cma_for_each() to check whether a DMA allocation is
from a CMA region.

Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
---
 include/linux/dma-map-ops.h |  6 ++++++
 kernel/dma/contiguous.c     | 24 ++++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index 9382785a2faa..9b91c839ceb5 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -106,6 +106,7 @@ struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp);
 void dma_free_contiguous(struct device *dev, struct page *page, size_t size);
 
 void dma_contiguous_early_fixup(phys_addr_t base, unsigned long size);
+bool dma_is_from_cma(phys_addr_t phys, size_t size);
 #else /* CONFIG_DMA_CMA */
 static inline struct cma *dev_get_cma_area(struct device *dev)
 {
@@ -145,6 +146,11 @@ static inline void dma_free_contiguous(struct device *dev, struct page *page,
 {
 	__free_pages(page, get_order(size));
 }
+
+static inline bool dma_is_from_cma(phys_addr_t phys, size_t size)
+{
+	return false;
+}
 #endif /* CONFIG_DMA_CMA*/
 
 #ifdef CONFIG_DMA_DECLARE_COHERENT
diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
index 03f52bd17120..0b1702bf39ca 100644
--- a/kernel/dma/contiguous.c
+++ b/kernel/dma/contiguous.c
@@ -130,6 +130,30 @@ struct cma *dev_get_cma_area(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(dev_get_cma_area);
 
+struct dma_cma_check_data {
+	phys_addr_t start;
+	phys_addr_t end;
+};
+
+static int dma_cma_check_area(struct cma *cma, void *data)
+{
+	struct dma_cma_check_data *chk = data;
+
+	if (cma_intersects(cma, chk->start, chk->end))
+		return 1;
+	return 0;
+}
+
+bool dma_is_from_cma(phys_addr_t phys, size_t size)
+{
+	struct dma_cma_check_data chk = {
+		.start = phys,
+		.end = phys + size - 1,
+	};
+
+	return cma_for_each_area(dma_cma_check_area, &chk) != 0;
+}
+
 #ifdef CONFIG_DMA_NUMA_CMA
 
 static struct cma *dma_contiguous_numa_area[MAX_NUMNODES];
-- 
2.55.0.795.g602f6c329a-goog