interconnect: core: Add dynamic id allocation support

The current interconnect framework relies on static IDs for node
creation and registration, which limits topologies with multiple
instances of the same interconnect provider. To address this,
introduce icc_node_create_dyn() and icc_link_nodes() APIs to
dynamically allocate IDs for interconnect nodes during creation
and link. This change removes the dependency on static IDs,
allowing multiple instances of the same hardware, such as EPSS L3.

Signed-off-by: Raviteja Laggyshetty <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Georgi Djakov <[email protected]>

Author: Raviteja Laggyshetty

drivers/interconnect/core.c

@@ -20,6 +20,8 @@
 
 #include "internal.h"
 
+#define ICC_DYN_ID_START 10000
+
 #define CREATE_TRACE_POINTS
 #include "trace.h"
 
@@ -826,7 +828,12 @@ static struct icc_node *icc_node_create_nolock(int id)
 	if (!node)
 		return ERR_PTR(-ENOMEM);
 
-	id = idr_alloc(&icc_idr, node, id, id + 1, GFP_KERNEL);
+	/* dynamic id allocation */
+	if (id == ICC_ALLOC_DYN_ID)
+		id = idr_alloc(&icc_idr, node, ICC_DYN_ID_START, 0, GFP_KERNEL);
+	else
+		id = idr_alloc(&icc_idr, node, id, id + 1, GFP_KERNEL);
+
 	if (id < 0) {
 		WARN(1, "%s: couldn't get idr\n", __func__);
 		kfree(node);
@@ -838,6 +845,25 @@ static struct icc_node *icc_node_create_nolock(int id)
 	return node;
 }
 
+/**
+ * icc_node_create_dyn() - create a node with dynamic id
+ *
+ * Return: icc_node pointer on success, or ERR_PTR() on error
+ */
+struct icc_node *icc_node_create_dyn(void)
+{
+	struct icc_node *node;
+
+	mutex_lock(&icc_lock);
+
+	node = icc_node_create_nolock(ICC_ALLOC_DYN_ID);
+
+	mutex_unlock(&icc_lock);
+
+	return node;
+}
+EXPORT_SYMBOL_GPL(icc_node_create_dyn);
+
 /**
  * icc_node_create() - create a node
  * @id: node id
@@ -884,6 +910,56 @@ void icc_node_destroy(int id)
 }
 EXPORT_SYMBOL_GPL(icc_node_destroy);
 
+/**
+ * icc_link_nodes() - create link between two nodes
+ * @src_node: source node
+ * @dst_node: destination node
+ *
+ * Create a link between two nodes. The nodes might belong to different
+ * interconnect providers and the @dst_node might not exist (if the
+ * provider driver has not probed yet). So just create the @dst_node
+ * and when the actual provider driver is probed, the rest of the node
+ * data is filled.
+ *
+ * Return: 0 on success, or an error code otherwise
+ */
+int icc_link_nodes(struct icc_node *src_node, struct icc_node **dst_node)
+{
+	struct icc_node **new;
+	int ret = 0;
+
+	if (!src_node->provider)
+		return -EINVAL;
+
+	mutex_lock(&icc_lock);
+
+	if (!*dst_node) {
+		*dst_node = icc_node_create_nolock(ICC_ALLOC_DYN_ID);
+
+		if (IS_ERR(*dst_node)) {
+			ret = PTR_ERR(*dst_node);
+			goto out;
+		}
+	}
+
+	new = krealloc(src_node->links,
+		       (src_node->num_links + 1) * sizeof(*src_node->links),
+		       GFP_KERNEL);
+	if (!new) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	src_node->links = new;
+	src_node->links[src_node->num_links++] = *dst_node;
+
+out:
+	mutex_unlock(&icc_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(icc_link_nodes);
+
 /**
  * icc_link_create() - create a link between two nodes
  * @node: source node id
@@ -962,6 +1038,10 @@ void icc_node_add(struct icc_node *node, struct icc_provider *provider)
 	node->avg_bw = node->init_avg;
 	node->peak_bw = node->init_peak;
 
+	if (node->id >= ICC_DYN_ID_START)
+		node->name = devm_kasprintf(provider->dev, GFP_KERNEL, "%s@%s",
+					    node->name, dev_name(provider->dev));
+
 	if (node->avg_bw || node->peak_bw) {
 		if (provider->pre_aggregate)
 			provider->pre_aggregate(node);

include/linux/interconnect-provider.h

@@ -116,8 +116,10 @@ struct icc_node {
 
 int icc_std_aggregate(struct icc_node *node, u32 tag, u32 avg_bw,
 		      u32 peak_bw, u32 *agg_avg, u32 *agg_peak);
+struct icc_node *icc_node_create_dyn(void);
 struct icc_node *icc_node_create(int id);
 void icc_node_destroy(int id);
+int icc_link_nodes(struct icc_node *src_node, struct icc_node **dst_node);
 int icc_link_create(struct icc_node *node, const int dst_id);
 void icc_node_add(struct icc_node *node, struct icc_provider *provider);
 void icc_node_del(struct icc_node *node);
@@ -136,6 +138,11 @@ static inline int icc_std_aggregate(struct icc_node *node, u32 tag, u32 avg_bw,
 	return -ENOTSUPP;
 }
 
+static inline struct icc_node *icc_node_create_dyn(void)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
 static inline struct icc_node *icc_node_create(int id)
 {
 	return ERR_PTR(-ENOTSUPP);
@@ -145,6 +152,11 @@ static inline void icc_node_destroy(int id)
 {
 }
 
+static inline int icc_link_nodes(struct icc_node *src_node, struct icc_node **dst_node)
+{
+	return -EOPNOTSUPP;
+}
+
 static inline int icc_link_create(struct icc_node *node, const int dst_id)
 {
 	return -ENOTSUPP;

include/linux/interconnect.h

@@ -20,6 +20,9 @@
 #define Mbps_to_icc(x)	((x) * 1000 / 8)
 #define Gbps_to_icc(x)	((x) * 1000 * 1000 / 8)
 
+/* macro to indicate dynamic id allocation */
+#define ICC_ALLOC_DYN_ID	-1
+
 struct icc_path;
 struct device;