[RFC PATCH 2/9] drivers: dma: of-dma: Add support for dma-request line routers

[Sricharan R]

In some socs dma requests lines from the peripherals to the
dma controller can be connected either directly or through
a crossbar router. The crossbar in turn maps the peripheral
request line to a free dma-controller request line. In such
cases the crossbar associated with the particular request lines
has to configured.

This add two APIS, one to register the crossbar router and other
to retrieve the router associated with a dma request line. The
peripheral's dma-specs mentions the dma-controller, request-line and
also the IP to which it is connected to via DT.

The dma-controller will have to check if a request line is routed
and then use that router's map/unmap function to configure the
request line.

Signed-off-by: Sricharan R <r.sricharan at ti.com>
---
 drivers/dma/of-dma.c   |   82 ++++++++++++++++++++++++++++++++++++++++++++++--
 include/linux/of_dma.h |   22 +++++++++++++
 2 files changed, 102 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c
index e8fe9dc..86129ef 100644
--- a/drivers/dma/of-dma.c
+++ b/drivers/dma/of-dma.c
@@ -19,7 +19,29 @@
 #include <linux/of_dma.h>
 
 static LIST_HEAD(of_dma_list);
+static LIST_HEAD(of_dma_router_list);
 static DEFINE_MUTEX(of_dma_lock);
+static DEFINE_MUTEX(of_dma_router_lock);
+
+/**
+ * of_dma_get_router_data - Get a DMA router in DT DMA routers list
+ * @phandle:	phandle to the dma router
+ *
+ * Finds a DMA router using matching phandle and returns the router
+ * specific data. Should be called from dma-controller xlate callback.
+ */
+void *of_dma_get_router_data(phandle router)
+{
+	struct of_dma_router *ofrouter;
+
+	list_for_each_entry(ofrouter, &of_dma_router_list, of_dma_routers) {
+		if (ofrouter->of_node->phandle == router)
+			return ofrouter->of_router_data;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL(of_dma_get_router_data);
 
 /**
  * of_dma_find_controller - Get a DMA controller in DT DMA helpers list
@@ -45,6 +67,39 @@ static struct of_dma *of_dma_find_controller(struct of_phandle_args *dma_spec)
 }
 
 /**
+ * of_dma_router_register - Register a DMA router to DT DMA helpers
+ * @np:			device node of DMA controller
+ * @data		pointer to controller specific data to be used by
+ *			dma-controller
+ *
+ * Returns 0 on success or appropriate errno value on error.
+ *
+ * Allocated memory should be freed with appropriate of_dma_router_free()
+ * call.
+ */
+int of_dma_router_register(struct device_node *np, void *data)
+{
+	struct of_dma_router *ofrouter;
+
+	if (!np || !data)
+		return -EINVAL;
+
+	ofrouter = kzalloc(sizeof(*ofrouter), GFP_KERNEL);
+	if (!ofrouter)
+		return -ENOMEM;
+
+	ofrouter->of_node = np;
+	ofrouter->of_router_data = data;
+
+	mutex_lock(&of_dma_router_lock);
+	list_add_tail(&ofrouter->of_dma_routers, &of_dma_router_list);
+	mutex_unlock(&of_dma_router_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL(of_dma_router_register);
+
+/**
  * 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
@@ -87,10 +142,10 @@ int of_dma_controller_register(struct device_node *np,
 EXPORT_SYMBOL_GPL(of_dma_controller_register);
 
 /**
- * of_dma_controller_free - Remove a DMA controller from DT DMA helpers list
+ * of_dma_router_free - Remove a DMA router from DT DMA routers list
  * @np:		device node of DMA controller
  *
- * Memory allocated by of_dma_controller_register() is freed here.
+ * Memory allocated by of_dma_router_register() is freed here.
  */
 void of_dma_controller_free(struct device_node *np)
 {
@@ -110,6 +165,29 @@ void of_dma_controller_free(struct device_node *np)
 EXPORT_SYMBOL_GPL(of_dma_controller_free);
 
 /**
+ * of_dma_controller_free - Remove a DMA controller from DT DMA helpers list
+ * @np:		device node of DMA controller
+ *
+ * Memory allocated by of_dma_router_register() is freed here.
+ */
+void of_dma_router_free(struct device_node *np)
+{
+	struct of_dma_router *ofrouter;
+
+	mutex_lock(&of_dma_router_lock);
+
+	list_for_each_entry(ofrouter, &of_dma_router_list, of_dma_routers)
+		if (ofrouter->of_node == np) {
+			list_del(&ofrouter->of_dma_routers);
+			kfree(ofrouter);
+			break;
+		}
+
+	mutex_unlock(&of_dma_router_lock);
+}
+EXPORT_SYMBOL_GPL(of_dma_router_free);
+
+/**
  * 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
diff --git a/include/linux/of_dma.h b/include/linux/of_dma.h
index ae36298..50962a0 100644
--- a/include/linux/of_dma.h
+++ b/include/linux/of_dma.h
@@ -26,6 +26,12 @@ struct of_dma {
 	void			*of_dma_data;
 };
 
+struct of_dma_router {
+	struct list_head	of_dma_routers;
+	struct device_node	*of_node;
+	void			*of_router_data;
+};
+
 struct of_dma_filter_info {
 	dma_cap_mask_t	dma_cap;
 	dma_filter_fn	filter_fn;
@@ -41,6 +47,9 @@ extern struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
 						     const char *name);
 extern struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
 		struct of_dma *ofdma);
+extern void *of_dma_get_router_data(phandle router);
+extern int of_dma_router_register(struct device_node *np, void *data);
+extern void of_dma_router_free(struct device_node *np);
 #else
 static inline int of_dma_controller_register(struct device_node *np,
 		struct dma_chan *(*of_dma_xlate)
@@ -66,6 +75,19 @@ static inline struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_s
 	return NULL;
 }
 
+static inline void *of_dma_get_router_data(phandle router)
+{
+	return NULL;
+}
+
+static inline int of_dma_router_register(struct device_node *np, void *data)
+{
+	return NULL;
+}
+
+static void of_dma_router_free(struct device_node *np)
+{
+}
 #endif
 
 #endif /* __LINUX_OF_DMA_H */
-- 
1.7.9.5