[RFC PATCH v2 04/10] dma-coherent: Allow checking if allocation is from dev coherent region

[Samiullah Khawaja]

Add an API that allows if a DMA allocation is from device coherent
region.

Signed-off-by: Samiullah Khawaja <skhawaja at google.com>
---
 include/linux/dma-map-ops.h |  3 +++
 kernel/dma/coherent.c       | 11 +++++++++++
 2 files changed, 14 insertions(+)

diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index 9b91c839ceb5..b13e5eebe6d3 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -162,6 +162,7 @@ int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size,
 int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr);
 int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma,
 		void *cpu_addr, size_t size, int *ret);
+bool dma_is_from_dev_coherent(struct device *dev, void *vaddr);
 #else
 static inline int dma_declare_coherent_memory(struct device *dev,
 		phys_addr_t phys_addr, dma_addr_t device_addr, size_t size)
@@ -172,6 +173,8 @@ static inline int dma_declare_coherent_memory(struct device *dev,
 #define dma_alloc_from_dev_coherent(dev, size, handle, ret) (0)
 #define dma_release_from_dev_coherent(dev, order, vaddr) (0)
 #define dma_mmap_from_dev_coherent(dev, vma, vaddr, order, ret) (0)
+#define dma_is_from_dev_coherent(dev, vaddr) (false)
+
 static inline void dma_release_coherent_memory(struct device *dev) { }
 #endif /* CONFIG_DMA_DECLARE_COHERENT */
 
diff --git a/kernel/dma/coherent.c b/kernel/dma/coherent.c
index bcdc0f76d2e8..76cbe11e1f90 100644
--- a/kernel/dma/coherent.c
+++ b/kernel/dma/coherent.c
@@ -231,6 +231,17 @@ int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr)
 	return __dma_release_from_coherent(mem, order, vaddr);
 }
 
+bool dma_is_from_dev_coherent(struct device *dev, void *vaddr)
+{
+	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
+
+	if (mem && vaddr >= mem->virt_base && vaddr <
+		   (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT)))
+		return true;
+
+	return false;
+}
+
 static int __dma_mmap_from_coherent(struct dma_coherent_mem *mem,
 		struct vm_area_struct *vma, void *vaddr, size_t size, int *ret)
 {
-- 
2.55.0.795.g602f6c329a-goog