1 files changed, 89 insertions, 0 deletions

diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c
index cbd4a8aff..1e1f2986e 100644
--- a/drivers/dma/of-dma.c
+++ b/drivers/dma/of-dma.c
@@ -45,6 +45,50 @@ static struct of_dma *of_dma_find_controller(struct of_phandle_args *dma_spec)
 }
 
 /**
+ * of_dma_router_xlate - translation function for router devices
+ * @dma_spec:	pointer to DMA specifier as found in the device tree
+ * @of_dma:	pointer to DMA controller data (router information)
+ *
+ * The function creates new dma_spec to be passed to the router driver's
+ * of_dma_route_allocate() function to prepare a dma_spec which will be used
+ * to request channel from the real DMA controller.
+ */
+static struct dma_chan *of_dma_router_xlate(struct of_phandle_args *dma_spec,
+					    struct of_dma *ofdma)
+{
+	struct dma_chan		*chan;
+	struct of_dma		*ofdma_target;
+	struct of_phandle_args	dma_spec_target;
+	void			*route_data;
+
+	/* translate the request for the real DMA controller */
+	memcpy(&dma_spec_target, dma_spec, sizeof(dma_spec_target));
+	route_data = ofdma->of_dma_route_allocate(&dma_spec_target, ofdma);
+	if (IS_ERR(route_data))
+		return NULL;
+
+	ofdma_target = of_dma_find_controller(&dma_spec_target);
+	if (!ofdma_target)
+		return NULL;
+
+	chan = ofdma_target->of_dma_xlate(&dma_spec_target, ofdma_target);
+	if (chan) {
+		chan->router = ofdma->dma_router;
+		chan->route_data = route_data;
+	} else {
+		ofdma->dma_router->route_free(ofdma->dma_router->dev,
+					      route_data);
+	}
+
+	/*
+	 * Need to put the node back since the ofdma->of_dma_route_allocate
+	 * has taken it for generating the new, translated dma_spec
+	 */
+	of_node_put(dma_spec_target.np);
+	return chan;
+}
+
+/**
  * of_dma_controller_register - Register a DMA controller to DT DMA helpers
  * @np:			device node of DMA controller
  * @of_dma_xlate:	translation function which converts a phandle
@@ -110,6 +154,51 @@ void of_dma_controller_free(struct device_node *np)
 EXPORT_SYMBOL_GPL(of_dma_controller_free);
 
 /**
+ * of_dma_router_register - Register a DMA router to DT DMA helpers as a
+ *			    controller
+ * @np:				device node of DMA router
+ * @of_dma_route_allocate:	setup function for the router which need to
+ *				modify the dma_spec for the DMA controller to
+ *				use and to set up the requested route.
+ * @dma_router:			pointer to dma_router structure to be used when
+ *				the route need to be free up.
+ *
+ * Returns 0 on success or appropriate errno value on error.
+ *
+ * Allocated memory should be freed with appropriate of_dma_controller_free()
+ * call.
+ */
+int of_dma_router_register(struct device_node *np,
+			   void *(*of_dma_route_allocate)
+			   (struct of_phandle_args *, struct of_dma *),
+			   struct dma_router *dma_router)
+{
+	struct of_dma	*ofdma;
+
+	if (!np || !of_dma_route_allocate || !dma_router) {
+		pr_err("%s: not enough information provided\n", __func__);
+		return -EINVAL;
+	}
+
+	ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL);
+	if (!ofdma)
+		return -ENOMEM;
+
+	ofdma->of_node = np;
+	ofdma->of_dma_xlate = of_dma_router_xlate;
+	ofdma->of_dma_route_allocate = of_dma_route_allocate;
+	ofdma->dma_router = dma_router;
+
+	/* Now queue of_dma controller structure in list */
+	mutex_lock(&of_dma_lock);
+	list_add_tail(&ofdma->of_dma_controllers, &of_dma_list);
+	mutex_unlock(&of_dma_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_dma_router_register);
+
+/**
  * of_dma_match_channel - Check if a DMA specifier matches name
  * @np:		device node to look for DMA channels
  * @name:	channel name to be matched