coresight: Store in-connections as well as out-connections

This will allow CATU to get its associated ETR in a generic way where
currently the enable path has some hard coded searches which avoid
the need to store input connections.

This also means that the full search for connected devices on removal
can be replaced with a loop through only the input and output devices.
Reviewed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: James Clark <james.clark@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20230425143542.2305069-10-james.clark@arm.com

drivers/hwtracing/coresight/coresight-core.c

@@ -1349,6 +1349,17 @@ static int coresight_orphan_match(struct device *dev, void *data)
 			ret = coresight_make_links(src_csdev, conn, dst_csdev);
 			if (ret)
 				return ret;
+
+			/*
+			 * Install the device connection. This also indicates that
+			 * the links are operational on both ends.
+			 */
+			conn->dest_dev = dst_csdev;
+			conn->src_dev = src_csdev;
+
+			ret = coresight_add_in_conn(conn);
+			if (ret)
+				return ret;
 		} else {
 			/* This component still has an orphan */
 			still_orphan = true;
@@ -1370,58 +1381,43 @@ static int coresight_fixup_orphan_conns(struct coresight_device *csdev)
 			 csdev, coresight_orphan_match);
 }
 
-static int coresight_remove_match(struct device *dev, void *data)
+/* coresight_remove_conns - Remove other device's references to this device */
+static void coresight_remove_conns(struct coresight_device *csdev)
 {
-	int i;
-	struct coresight_device *csdev, *iterator;
+	int i, j;
 	struct coresight_connection *conn;
 
-	csdev = data;
-	iterator = to_coresight_device(dev);
-
-	/* No need to check oneself */
-	if (csdev == iterator)
-		return 0;
-
 	/*
-	 * Circle throuch all the connection of that component.  If we find
-	 * a connection whose name matches @csdev, remove it.
+	 * Remove the input connection references from the destination device
+	 * for each output connection.
 	 */
-	for (i = 0; i < iterator->pdata->nr_outconns; i++) {
-		conn = iterator->pdata->out_conns[i];
-
-		/* Child_dev being set signifies that the links were made */
-		if (csdev->dev.fwnode == conn->dest_fwnode && conn->dest_dev) {
-			iterator->orphan = true;
-			coresight_remove_links(iterator, conn);
-			conn->dest_dev = NULL;
-			/* No need to continue */
-			break;
-		}
+	for (i = 0; i < csdev->pdata->nr_outconns; i++) {
+		conn = csdev->pdata->out_conns[i];
+		if (!conn->dest_dev)
+			continue;
+
+		for (j = 0; j < conn->dest_dev->pdata->nr_inconns; ++j)
+			if (conn->dest_dev->pdata->in_conns[j] == conn) {
+				conn->dest_dev->pdata->in_conns[j] = NULL;
+				break;
+			}
 	}
 
 	/*
-	 * Returning '0' ensures that all known component on the
-	 * bus will be checked.
+	 * For all input connections, remove references to this device.
+	 * Connection objects are shared so modifying this device's input
+	 * connections affects the other device's output connection.
 	 */
-	return 0;
-}
+	for (i = 0; i < csdev->pdata->nr_inconns; ++i) {
+		conn = csdev->pdata->in_conns[i];
+		/* Input conns array is sparse */
+		if (!conn)
+			continue;
 
-/*
- * coresight_remove_conns - Remove references to this given devices
- * from the connections of other devices.
- */
-static void coresight_remove_conns(struct coresight_device *csdev)
-{
-	/*
-	 * Another device will point to this device only if there is
-	 * an output port connected to this one. i.e, if the device
-	 * doesn't have at least one input port, there is no point
-	 * in searching all the devices.
-	 */
-	if (csdev->pdata->high_inport)
-		bus_for_each_dev(&coresight_bustype, NULL,
-				 csdev, coresight_remove_match);
+		conn->src_dev->orphan = true;
+		coresight_remove_links(conn->src_dev, conn);
+		conn->dest_dev = NULL;
+	}
 }
 
 /**
@@ -1532,6 +1528,7 @@ void coresight_release_platform_data(struct coresight_device *csdev,
 		devm_kfree(dev, conns[i]);
 	}
 	devm_kfree(dev, pdata->out_conns);
+	devm_kfree(dev, pdata->in_conns);
 	devm_kfree(dev, pdata);
 	if (csdev)
 		coresight_remove_conns_sysfs_group(csdev);

drivers/hwtracing/coresight/coresight-platform.c

@@ -70,6 +70,35 @@ coresight_add_out_conn(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(coresight_add_out_conn);
 
+/*
+ * Add an input connection reference to @out_conn in the target's in_conns array
+ *
+ * @out_conn: Existing output connection to store as an input on the
+ *	      connection's remote device.
+ */
+int coresight_add_in_conn(struct coresight_connection *out_conn)
+{
+	int i;
+	struct device *dev = out_conn->dest_dev->dev.parent;
+	struct coresight_platform_data *pdata = out_conn->dest_dev->pdata;
+
+	for (i = 0; i < pdata->nr_inconns; ++i)
+		if (!pdata->in_conns[i]) {
+			pdata->in_conns[i] = out_conn;
+			return 0;
+		}
+
+	pdata->nr_inconns++;
+	pdata->in_conns =
+		devm_krealloc_array(dev, pdata->in_conns, pdata->nr_inconns,
+				    sizeof(*pdata->in_conns), GFP_KERNEL);
+	if (!pdata->in_conns)
+		return -ENOMEM;
+	pdata->in_conns[pdata->nr_inconns - 1] = out_conn;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(coresight_add_in_conn);
+
 static struct device *
 coresight_find_device_by_fwnode(struct fwnode_handle *fwnode)
 {
@@ -240,7 +269,7 @@ static int of_coresight_get_cpu(struct device *dev)
 
 /*
  * of_coresight_parse_endpoint : Parse the given output endpoint @ep
- * and fill the connection information in @conn
+ * and fill the connection information in @pdata->out_conns
  *
  * Parses the local port, remote device name and the remote port.
  *

drivers/hwtracing/coresight/coresight-sysfs.c

@@ -173,12 +173,6 @@ int coresight_make_links(struct coresight_device *orig,
 			break;
 
 		conn->link = link;
-
-		/*
-		 * Install the device connection. This also indicates that
-		 * the links are operational on both ends.
-		 */
-		conn->dest_dev = target;
 		return 0;
 	} while (0);
 
@@ -202,5 +196,4 @@ void coresight_remove_links(struct coresight_device *orig,
 	devm_kfree(&orig->dev, conn->link->orig_name);
 	devm_kfree(&orig->dev, conn->link);
 	conn->link = NULL;
-	conn->dest_dev = NULL;
 }

include/linux/coresight.h

@@ -106,6 +106,9 @@ union coresight_dev_subtype {
  * @nr_outconns: Number of elements for the output connections.
  * @out_conns: Array of nr_outconns pointers to connections from this
  *	       component.
+ * @in_conns: Sparse array of pointers to input connections. Sparse
+ *            because the source device owns the connection so when it's
+ *            unloaded the connection leaves an empty slot.
  */
 struct coresight_platform_data {
 	int high_inport;
@@ -113,6 +116,7 @@ struct coresight_platform_data {
 	int nr_inconns;
 	int nr_outconns;
 	struct coresight_connection **out_conns;
+	struct coresight_connection **in_conns;
 };
 
 /**
@@ -173,6 +177,26 @@ struct coresight_desc {
  * @dest_dev:	a @coresight_device representation of the component
 		connected to @src_port. NULL until the device is created
  * @link: Representation of the connection as a sysfs link.
+ *
+ * The full connection structure looks like this, where in_conns store
+ * references to same connection as the source device's out_conns.
+ *
+ * +-----------------------------+   +-----------------------------+
+ * |coresight_device             |   |coresight_connection         |
+ * |-----------------------------|   |-----------------------------|
+ * |                             |   |                             |
+ * |                             |   |                    dest_dev*|<--
+ * |pdata->out_conns[nr_outconns]|<->|src_dev*                     |   |
+ * |                             |   |                             |   |
+ * +-----------------------------+   +-----------------------------+   |
+ *                                                                     |
+ *                                   +-----------------------------+   |
+ *                                   |coresight_device             |   |
+ *                                   |------------------------------   |
+ *                                   |                             |   |
+ *                                   |  pdata->in_conns[nr_inconns]|<--
+ *                                   |                             |
+ *                                   +-----------------------------+
  */
 struct coresight_connection {
 	int src_port;
@@ -180,6 +204,7 @@ struct coresight_connection {
 	struct fwnode_handle *dest_fwnode;
 	struct coresight_device *dest_dev;
 	struct coresight_sysfs_link *link;
+	struct coresight_device *src_dev;
 };
 
 /**
@@ -616,5 +641,6 @@ struct coresight_connection *
 coresight_add_out_conn(struct device *dev,
 		       struct coresight_platform_data *pdata,
 		       const struct coresight_connection *new_conn);
+int coresight_add_in_conn(struct coresight_connection *conn);
 
 #endif		/* _LINUX_COREISGHT_H */