dma-mapping: Add dma_release_coherent_memory to DMA API

Add dma_release_coherent_memory to DMA API to allow dma
user call it to release dev->dma_mem when the device is
removed.
Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220422062436.14384-2-mark-pk.tsai@mediatek.comSigned-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

include/linux/dma-map-ops.h

@@ -166,6 +166,7 @@ static inline void dma_pernuma_cma_reserve(void) { }
 #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,
 		dma_addr_t *dma_handle, void **ret);
 int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr);
@@ -177,6 +178,8 @@ static inline int dma_declare_coherent_memory(struct device *dev,
 {
 	return -ENOSYS;
 }
+
+#define dma_release_coherent_memory(dev) (0)
 #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)

kernel/dma/coherent.c

@@ -74,7 +74,7 @@ static struct dma_coherent_mem *dma_init_coherent_memory(phys_addr_t phys_addr,
 	return ERR_PTR(-ENOMEM);
 }
 
-static void dma_release_coherent_memory(struct dma_coherent_mem *mem)
+static void _dma_release_coherent_memory(struct dma_coherent_mem *mem)
 {
 	if (!mem)
 		return;
@@ -126,10 +126,16 @@ int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
 
 	ret = dma_assign_coherent_memory(dev, mem);
 	if (ret)
-		dma_release_coherent_memory(mem);
+		_dma_release_coherent_memory(mem);
 	return ret;
 }
 
+void dma_release_coherent_memory(struct device *dev)
+{
+	if (dev)
+		_dma_release_coherent_memory(dev->dma_mem);
+}
+
 static void *__dma_alloc_from_coherent(struct device *dev,
 				       struct dma_coherent_mem *mem,
 				       ssize_t size, dma_addr_t *dma_handle)