[PATCH RFC 04/12] dma-coherent: add base and size APIs

[Francesco Valla <francesco@valla.it>]

Add two new APIs for the dma coherent memory to get the base and size of
the pool associated to a device.

Signed-off-by: Francesco Valla <francesco@valla.it>
---
 include/linux/dma-map-ops.h | 10 ++++++++++
 kernel/dma/coherent.c       | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index 8fae2b7deb20..580b69321d56 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -156,6 +156,8 @@ 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);
+size_t dma_dev_coherent_size(struct device *dev);
+dma_addr_t dma_dev_coherent_base(struct device *dev);
 #else
 static inline int dma_declare_coherent_memory(struct device *dev,
 		phys_addr_t phys_addr, dma_addr_t device_addr, size_t size)
@@ -167,6 +169,14 @@ static inline int dma_declare_coherent_memory(struct device *dev,
 #define dma_release_from_dev_coherent(dev, order, vaddr) (0)
 #define dma_mmap_from_dev_coherent(dev, vma, vaddr, order, ret) (0)
 static inline void dma_release_coherent_memory(struct device *dev) { }
+static inline size_t dma_dev_coherent_size(struct device *dev)
+{
+	return 0;
+}
+static inline dma_addr_t dma_dev_coherent_base(struct device *dev)
+{
+	return DMA_MAPPING_ERROR;
+}
 #endif /* CONFIG_DMA_DECLARE_COHERENT */
 
 #ifdef CONFIG_DMA_GLOBAL_POOL
diff --git a/kernel/dma/coherent.c b/kernel/dma/coherent.c
index 45bbae947f4b..f4aa5813604b 100644
--- a/kernel/dma/coherent.c
+++ b/kernel/dma/coherent.c
@@ -277,6 +277,40 @@ int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma,
 	return __dma_mmap_from_coherent(mem, vma, vaddr, size, ret);
 }
 
+/**
+ * dma_dev_coherent_size() - total size of the device coherent pool
+ * @dev:	device from which we allocate memory
+ *
+ * Returns the total size of the coherent memory pool associated to the given
+ * device, or 0 in case of no pool.
+ */
+size_t dma_dev_coherent_size(struct device *dev)
+{
+	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
+
+	if (!mem)
+		return 0;
+
+	return (mem->size << PAGE_SHIFT);
+}
+
+/**
+ * dma_dev_coherent_base() - base address of the device coherent pool
+ * @dev:	device from which we allocate memory
+ *
+ * Returns the base address of the coherent memory pool associated with the
+ * device, or DMA_MAPPING_ERROR in case of no pool.
+ */
+dma_addr_t dma_dev_coherent_base(struct device *dev)
+{
+	struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
+
+	if (!mem)
+		return DMA_MAPPING_ERROR;
+
+	return dma_get_device_base(dev, mem);
+}
+
 #ifdef CONFIG_DMA_GLOBAL_POOL
 static struct dma_coherent_mem *dma_coherent_default_memory __ro_after_init;
 

-- 
2.55.0