Currently we support only platform data for specifying the interconnect
endpoints. As now the endpoints are hard-coded into the consumer driver
this may lead to complications when a single driver is used by multiple
SoCs, which may have different interconnect topology.
To avoid cluttering the consumer drivers, introduce a translation function
to help us get the board specific interconnect data from device-tree.

Signed-off-by: Georgi Djakov <georgi.dja...@linaro.org>
Reviewed-by: Evan Green <evgr...@chromium.org>
---
 drivers/interconnect/core.c  | 78 ++++++++++++++++++++++++++++++++++++
 include/linux/interconnect.h |  7 ++++
 2 files changed, 85 insertions(+)

diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
index 9ca39aca4982..8f874d1b0a0f 100644
--- a/drivers/interconnect/core.c
+++ b/drivers/interconnect/core.c
@@ -15,6 +15,7 @@
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
+#include <linux/of.h>
 #include <linux/overflow.h>
 
 static DEFINE_IDR(icc_idr);
@@ -192,6 +193,83 @@ static int apply_constraints(struct icc_path *path)
        return ret;
 }
 
+/**
+ * of_icc_get() - get a path handle from a DT node based on name
+ * @dev: device pointer for the consumer device
+ * @name: interconnect path name
+ *
+ * This function will search for a path two endpoints and return an
+ * icc_path handle on success. Use icc_put() to release constraints when
+ * they are not needed anymore.
+ * If the interconnect API is disabled, NULL is returned and the consumer
+ * drivers will still build. Drivers are free to handle this specifically,
+ * but they don't have to. NULL is also returned when the "interconnects"
+ * DT property is missing.
+ *
+ * Return: icc_path pointer on success or ERR_PTR() on error. NULL is returned
+ * when the API is disabled or the "interconnects" DT property is missing.
+ */
+struct icc_path *of_icc_get(struct device *dev, const char *name)
+{
+       struct device_node *np = NULL;
+       struct of_phandle_args src_args, dst_args;
+       u32 src_id, dst_id;
+       int idx = 0;
+       int ret;
+
+       if (!dev || !dev->of_node)
+               return ERR_PTR(-ENODEV);
+
+       np = dev->of_node;
+
+       /*
+        * When the consumer DT node do not have "interconnects" property
+        * return a NULL path to skip setting constraints.
+        */
+       if (!of_find_property(np, "interconnects", NULL))
+               return NULL;
+
+       /*
+        * We use a combination of phandle and specifier for endpoint. For now
+        * lets support only global ids and extend this is the future if needed
+        * without breaking DT compatibility.
+        */
+       if (name) {
+               idx = of_property_match_string(np, "interconnect-names", name);
+               if (idx < 0)
+                       return ERR_PTR(idx);
+       }
+
+       ret = of_parse_phandle_with_args(np, "interconnects",
+                                        "#interconnect-cells", idx * 2,
+                                        &src_args);
+       if (ret)
+               return ERR_PTR(ret);
+
+       of_node_put(src_args.np);
+
+       if (!src_args.args_count || src_args.args_count > 1)
+               return ERR_PTR(-EINVAL);
+
+       src_id = src_args.args[0];
+
+       ret = of_parse_phandle_with_args(np, "interconnects",
+                                        "#interconnect-cells", idx * 2 + 1,
+                                        &dst_args);
+       if (ret)
+               return ERR_PTR(ret);
+
+       of_node_put(dst_args.np);
+
+       if (!dst_args.args_count || dst_args.args_count > 1)
+               return ERR_PTR(-EINVAL);
+
+       dst_id = dst_args.args[0];
+
+       return icc_get(dev, src_id, dst_id);
+}
+EXPORT_SYMBOL_GPL(of_icc_get);
+
 /**
  * icc_set() - set constraints on an interconnect path between two endpoints
  * @path: reference to the path returned by icc_get()
diff --git a/include/linux/interconnect.h b/include/linux/interconnect.h
index 593215371fd6..ae6744da9bc2 100644
--- a/include/linux/interconnect.h
+++ b/include/linux/interconnect.h
@@ -17,6 +17,7 @@ struct device;
 
 struct icc_path *icc_get(struct device *dev, const int src_id,
                         const int dst_id);
+struct icc_path *of_icc_get(struct device *dev, const char *name);
 void icc_put(struct icc_path *path);
 int icc_set(struct icc_path *path, u32 avg_bw, u32 peak_bw);
 
@@ -28,6 +29,12 @@ static inline struct icc_path *icc_get(struct device *dev, 
const int src_id,
        return NULL;
 }
 
+static inline struct icc_path *of_icc_get(struct device *dev,
+                                         const char *name)
+{
+       return NULL;
+}
+
 static inline void icc_put(struct icc_path *path)
 {
 }

Reply via email to