[PATCH] dmaengine: add a new helper dmam_async_device_register

[Huang Shijie]

This patch adds the dmam_async_device_register for DMA code.
Use the Devres to call the release for the DMA engine driver.

Signed-off-by: Huang Shijie <sjhuang@xxxxxxxxxxx>
---
 Documentation/driver-model/devres.txt |  1 +
 drivers/dma/dmaengine.c               | 35 +++++++++++++++++++++++++++
 include/linux/dmaengine.h             |  1 +
 3 files changed, 37 insertions(+)

diff --git a/Documentation/driver-model/devres.txt b/Documentation/driver-model/devres.txt
index a3e8bceb5f19..26c6de621446 100644
--- a/Documentation/driver-model/devres.txt
+++ b/Documentation/driver-model/devres.txt
@@ -240,6 +240,7 @@ CLOCK
   devm_of_clk_add_hw_provider()
 
 DMA
+  dmam_async_device_register()
   dmam_alloc_coherent()
   dmam_alloc_attrs()
   dmam_declare_coherent_memory()
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index 84ac38dbdb65..2477af0bdfc7 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -1135,6 +1135,41 @@ void dma_async_device_unregister(struct dma_device *device)
 }
 EXPORT_SYMBOL(dma_async_device_unregister);
 
+static void dmam_device_release(struct device *dev, void *res)
+{
+	struct dma_device *device;
+
+	device = *(struct dma_device **)res;
+	dma_async_device_unregister(device);
+}
+
+/**
+ * dmam_async_device_register - registers DMA devices found
+ * @device: &dma_device
+ *
+ * The operation is managed and will be undone on driver detach.
+ */
+int dmam_async_device_register(struct dma_device *device)
+{
+	void *p;
+	int ret;
+
+	p = devres_alloc(dmam_device_release, sizeof(void *), GFP_KERNEL);
+	if (!p)
+		return -ENOMEM;
+
+	ret = dma_async_device_register(device);
+	if (!ret) {
+		*(struct dma_device **)p = device;
+		devres_add(device->dev, p);
+	} else {
+		devres_free(p);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(dmam_async_device_register);
+
 struct dmaengine_unmap_pool {
 	struct kmem_cache *cache;
 	const char *name;
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index c8c3a7a93802..b98bced0b98e 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -1406,6 +1406,7 @@ static inline int dmaengine_desc_free(struct dma_async_tx_descriptor *desc)
 /* --- DMA device --- */
 
 int dma_async_device_register(struct dma_device *device);
+int dmam_async_device_register(struct dma_device *device);
 void dma_async_device_unregister(struct dma_device *device);
 void dma_run_dependencies(struct dma_async_tx_descriptor *tx);
 struct dma_chan *dma_get_slave_channel(struct dma_chan *chan);
-- 
2.17.1