interconnect: Allow endpoints translation via DT

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.

Reviewed-by: Evan Green <evgreen@chromium.org>
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 149 insertions, 0 deletions

diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
index 2b937b4f43c4..a8c2bd35197f 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);
@@ -194,6 +195,152 @@ out:
 	return ret;
 }
 
+/* of_icc_xlate_onecell() - Translate function using a single index.
+ * @spec: OF phandle args to map into an interconnect node.
+ * @data: private data (pointer to struct icc_onecell_data)
+ *
+ * This is a generic translate function that can be used to model simple
+ * interconnect providers that have one device tree node and provide
+ * multiple interconnect nodes. A single cell is used as an index into
+ * an array of icc nodes specified in the icc_onecell_data struct when
+ * registering the provider.
+ */
+struct icc_node *of_icc_xlate_onecell(struct of_phandle_args *spec,
+				      void *data)
+{
+	struct icc_onecell_data *icc_data = data;
+	unsigned int idx = spec->args[0];
+
+	if (idx >= icc_data->num_nodes) {
+		pr_err("%s: invalid index %u\n", __func__, idx);
+		return ERR_PTR(-EINVAL);
+	}
+
+	return icc_data->nodes[idx];
+}
+EXPORT_SYMBOL_GPL(of_icc_xlate_onecell);
+
+/**
+ * of_icc_get_from_provider() - Look-up interconnect node
+ * @spec: OF phandle args to use for look-up
+ *
+ * Looks for interconnect provider under the node specified by @spec and if
+ * found, uses xlate function of the provider to map phandle args to node.
+ *
+ * Returns a valid pointer to struct icc_node on success or ERR_PTR()
+ * on failure.
+ */
+static struct icc_node *of_icc_get_from_provider(struct of_phandle_args *spec)
+{
+	struct icc_node *node = ERR_PTR(-EPROBE_DEFER);
+	struct icc_provider *provider;
+
+	if (!spec || spec->args_count != 1)
+		return ERR_PTR(-EINVAL);
+
+	mutex_lock(&icc_lock);
+	list_for_each_entry(provider, &icc_providers, provider_list) {
+		if (provider->dev->of_node == spec->np)
+			node = provider->xlate(spec, provider->data);
+		if (!IS_ERR(node))
+			break;
+	}
+	mutex_unlock(&icc_lock);
+
+	return node;
+}
+
+/**
+ * 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 between 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.
+ *
+ * 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 icc_path *path = ERR_PTR(-EPROBE_DEFER);
+	struct icc_node *src_node, *dst_node;
+	struct device_node *np = NULL;
+	struct of_phandle_args src_args, dst_args;
+	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 in 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);
+
+	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);
+
+	src_node = of_icc_get_from_provider(&src_args);
+
+	if (IS_ERR(src_node)) {
+		if (PTR_ERR(src_node) != -EPROBE_DEFER)
+			dev_err(dev, "error finding src node: %ld\n",
+				PTR_ERR(src_node));
+		return ERR_CAST(src_node);
+	}
+
+	dst_node = of_icc_get_from_provider(&dst_args);
+
+	if (IS_ERR(dst_node)) {
+		if (PTR_ERR(dst_node) != -EPROBE_DEFER)
+			dev_err(dev, "error finding dst node: %ld\n",
+				PTR_ERR(dst_node));
+		return ERR_CAST(dst_node);
+	}
+
+	mutex_lock(&icc_lock);
+	path = path_find(dev, src_node, dst_node);
+	if (IS_ERR(path))
+		dev_err(dev, "%s: invalid path=%ld\n", __func__, PTR_ERR(path));
+	mutex_unlock(&icc_lock);
+
+	return path;
+}
+EXPORT_SYMBOL_GPL(of_icc_get);
+
 /**
  * icc_set_bw() - set bandwidth constraints on an interconnect path
  * @path: reference to the path returned by icc_get()
@@ -519,6 +666,8 @@ int icc_provider_add(struct icc_provider *provider)
 {
 	if (WARN_ON(!provider->set))
 		return -EINVAL;
+	if (WARN_ON(!provider->xlate))
+		return -EINVAL;
 
 	mutex_lock(&icc_lock);