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From: Mathieu Poirier <mathieu.poirier@linaro.org>
To: gregkh@linuxfoundation.org
Cc: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 04/23] coresight: Expose device connections via sysfs
Date: Mon, 18 May 2020 12:02:23 -0600	[thread overview]
Message-ID: <20200518180242.7916-5-mathieu.poirier@linaro.org> (raw)
In-Reply-To: <20200518180242.7916-1-mathieu.poirier@linaro.org>

From: Suzuki K Poulose <suzuki.poulose@arm.com>

Coresight device connections are a bit complicated and is not
exposed currently to the user. One has to look at the platform
descriptions (DT bindings or ACPI bindings) to make an understanding.
Given the new naming scheme, it will be helpful to have this information
to choose the appropriate devices for tracing. This patch exposes
the device connections via links in the sysfs directories.

e.g, for a connection devA[OutputPort_X] -> devB[InputPort_Y]
is represented as two symlinks:

  /sys/bus/coresight/.../devA/out:X -> /sys/bus/coresight/.../devB
  /sys/bus/coresight/.../devB/in:Y  -> /sys/bus/coresight/.../devA

Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
[Revised to use the generic sysfs links functions & link structures.
Provides a connections sysfs group in each device to hold the links.]
Co-developed-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 drivers/hwtracing/coresight/coresight-priv.h  |  5 ++
 drivers/hwtracing/coresight/coresight-sysfs.c | 80 +++++++++++++++++++
 drivers/hwtracing/coresight/coresight.c       | 46 ++++++++---
 include/linux/coresight.h                     |  2 +
 4 files changed, 121 insertions(+), 12 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
index a4a658d46045..5a36f0f50899 100644
--- a/drivers/hwtracing/coresight/coresight-priv.h
+++ b/drivers/hwtracing/coresight/coresight-priv.h
@@ -157,6 +157,11 @@ int coresight_add_sysfs_link(struct coresight_sysfs_link *info);
 void coresight_remove_sysfs_link(struct coresight_sysfs_link *info);
 int coresight_create_conns_sysfs_group(struct coresight_device *csdev);
 void coresight_remove_conns_sysfs_group(struct coresight_device *csdev);
+int coresight_make_links(struct coresight_device *orig,
+			 struct coresight_connection *conn,
+			 struct coresight_device *target);
+void coresight_remove_links(struct coresight_device *orig,
+			    struct coresight_connection *conn);
 
 #ifdef CONFIG_CORESIGHT_SOURCE_ETM3X
 extern int etm_readl_cp14(u32 off, unsigned int *val);
diff --git a/drivers/hwtracing/coresight/coresight-sysfs.c b/drivers/hwtracing/coresight/coresight-sysfs.c
index 6759f78733ab..82afeaf2ccc4 100644
--- a/drivers/hwtracing/coresight/coresight-sysfs.c
+++ b/drivers/hwtracing/coresight/coresight-sysfs.c
@@ -122,3 +122,83 @@ void coresight_remove_sysfs_link(struct coresight_sysfs_link *info)
 	info->orig->nr_links--;
 	info->target->nr_links--;
 }
+
+/*
+ * coresight_make_links: Make a link for a connection from a @orig
+ * device to @target, represented by @conn.
+ *
+ *   e.g, for devOrig[output_X] -> devTarget[input_Y] is represented
+ *   as two symbolic links :
+ *
+ *	/sys/.../devOrig/out:X	-> /sys/.../devTarget/
+ *	/sys/.../devTarget/in:Y	-> /sys/.../devOrig/
+ *
+ * The link names are allocated for a device where it appears. i.e, the
+ * "out" link on the master and "in" link on the slave device.
+ * The link info is stored in the connection record for avoiding
+ * the reconstruction of names for removal.
+ */
+int coresight_make_links(struct coresight_device *orig,
+			 struct coresight_connection *conn,
+			 struct coresight_device *target)
+{
+	int ret = -ENOMEM;
+	char *outs = NULL, *ins = NULL;
+	struct coresight_sysfs_link *link = NULL;
+
+	do {
+		outs = devm_kasprintf(&orig->dev, GFP_KERNEL,
+				      "out:%d", conn->outport);
+		if (!outs)
+			break;
+		ins = devm_kasprintf(&target->dev, GFP_KERNEL,
+				     "in:%d", conn->child_port);
+		if (!ins)
+			break;
+		link = devm_kzalloc(&orig->dev,
+				    sizeof(struct coresight_sysfs_link),
+				    GFP_KERNEL);
+		if (!link)
+			break;
+
+		link->orig = orig;
+		link->target = target;
+		link->orig_name = outs;
+		link->target_name = ins;
+
+		ret = coresight_add_sysfs_link(link);
+		if (ret)
+			break;
+
+		conn->link = link;
+
+		/*
+		 * Install the device connection. This also indicates that
+		 * the links are operational on both ends.
+		 */
+		conn->child_dev = target;
+		return 0;
+	} while (0);
+
+	return ret;
+}
+
+/*
+ * coresight_remove_links: Remove the sysfs links for a given connection @conn,
+ * from @orig device to @target device. See coresight_make_links() for more
+ * details.
+ */
+void coresight_remove_links(struct coresight_device *orig,
+			    struct coresight_connection *conn)
+{
+	if (!orig || !conn->link)
+		return;
+
+	coresight_remove_sysfs_link(conn->link);
+
+	devm_kfree(&conn->child_dev->dev, conn->link->target_name);
+	devm_kfree(&orig->dev, conn->link->orig_name);
+	devm_kfree(&orig->dev, conn->link);
+	conn->link = NULL;
+	conn->child_dev = NULL;
+}
diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
index 07f66a3968f1..4f10cfa9dc18 100644
--- a/drivers/hwtracing/coresight/coresight.c
+++ b/drivers/hwtracing/coresight/coresight.c
@@ -1031,7 +1031,7 @@ static void coresight_device_release(struct device *dev)
 
 static int coresight_orphan_match(struct device *dev, void *data)
 {
-	int i;
+	int i, ret = 0;
 	bool still_orphan = false;
 	struct coresight_device *csdev, *i_csdev;
 	struct coresight_connection *conn;
@@ -1056,19 +1056,23 @@ static int coresight_orphan_match(struct device *dev, void *data)
 		/* We have found at least one orphan connection */
 		if (conn->child_dev == NULL) {
 			/* Does it match this newly added device? */
-			if (conn->child_fwnode == csdev->dev.fwnode)
-				conn->child_dev = csdev;
-			else
+			if (conn->child_fwnode == csdev->dev.fwnode) {
+				ret = coresight_make_links(i_csdev,
+							   conn, csdev);
+				if (ret)
+					return ret;
+			} else {
 				/* This component still has an orphan */
 				still_orphan = true;
+			}
 		}
 	}
 
 	i_csdev->orphan = still_orphan;
 
 	/*
-	 * Returning '0' ensures that all known component on the
-	 * bus will be checked.
+	 * Returning '0' in case we didn't encounter any error,
+	 * ensures that all known component on the bus will be checked.
 	 */
 	return 0;
 }
@@ -1082,15 +1086,21 @@ static int coresight_fixup_orphan_conns(struct coresight_device *csdev)
 
 static int coresight_fixup_device_conns(struct coresight_device *csdev)
 {
-	int i;
+	int i, ret = 0;
 
 	for (i = 0; i < csdev->pdata->nr_outport; i++) {
 		struct coresight_connection *conn = &csdev->pdata->conns[i];
 
 		conn->child_dev =
 			coresight_find_csdev_by_fwnode(conn->child_fwnode);
-		if (!conn->child_dev)
+		if (conn->child_dev) {
+			ret = coresight_make_links(csdev, conn,
+						   conn->child_dev);
+			if (ret)
+				break;
+		} else {
 			csdev->orphan = true;
+		}
 	}
 
 	return 0;
@@ -1121,7 +1131,7 @@ static int coresight_remove_match(struct device *dev, void *data)
 
 		if (csdev->dev.fwnode == conn->child_fwnode) {
 			iterator->orphan = true;
-			conn->child_dev = NULL;
+			coresight_remove_links(iterator, conn);
 			/*
 			 * Drop the reference to the handle for the remote
 			 * device acquired in parsing the connections from
@@ -1215,13 +1225,23 @@ void coresight_release_platform_data(struct coresight_device *csdev,
 				     struct coresight_platform_data *pdata)
 {
 	int i;
+	struct coresight_connection *conns = pdata->conns;
 
 	for (i = 0; i < pdata->nr_outport; i++) {
-		if (pdata->conns[i].child_fwnode) {
-			fwnode_handle_put(pdata->conns[i].child_fwnode);
+		/* If we have made the links, remove them now */
+		if (csdev && conns[i].child_dev)
+			coresight_remove_links(csdev, &conns[i]);
+		/*
+		 * Drop the refcount and clear the handle as this device
+		 * is going away
+		 */
+		if (conns[i].child_fwnode) {
+			fwnode_handle_put(conns[i].child_fwnode);
 			pdata->conns[i].child_fwnode = NULL;
 		}
 	}
+	if (csdev)
+		coresight_remove_conns_sysfs_group(csdev);
 }
 
 struct coresight_device *coresight_register(struct coresight_desc *desc)
@@ -1303,7 +1323,9 @@ struct coresight_device *coresight_register(struct coresight_desc *desc)
 
 	mutex_lock(&coresight_mutex);
 
-	ret = coresight_fixup_device_conns(csdev);
+	ret = coresight_create_conns_sysfs_group(csdev);
+	if (!ret)
+		ret = coresight_fixup_device_conns(csdev);
 	if (!ret)
 		ret = coresight_fixup_orphan_conns(csdev);
 	if (!ret)
diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index a2ec25e02ca9..ccd17304d7bd 100644
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h
@@ -140,12 +140,14 @@ struct coresight_desc {
  * @chid_fwnode: remote component's fwnode handle.
  * @child_dev:	a @coresight_device representation of the component
 		connected to @outport.
+ * @link: Representation of the connection as a sysfs link.
  */
 struct coresight_connection {
 	int outport;
 	int child_port;
 	struct fwnode_handle *child_fwnode;
 	struct coresight_device *child_dev;
+	struct coresight_sysfs_link *link;
 };
 
 /**
-- 
2.20.1


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  parent reply	other threads:[~2020-05-18 18:03 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-18 18:02 [PATCH 00/23] coresight: next for v5.8 Mathieu Poirier
2020-05-18 18:02 ` [PATCH 01/23] coresight: Pass coresight_device for coresight_release_platform_data Mathieu Poirier
2020-05-18 18:02 ` [PATCH 02/23] coresight: Add return value for fixup connections Mathieu Poirier
2020-05-18 18:02 ` [PATCH 03/23] coresight: Add generic sysfs link creation functions Mathieu Poirier
2020-05-18 18:02 ` Mathieu Poirier [this message]
2020-05-18 18:02 ` [PATCH 05/23] coresight: cti: Add in sysfs links to other coresight devices Mathieu Poirier
2020-05-18 18:02 ` [PATCH 06/23] coresight: docs: Add information about the topology representations Mathieu Poirier
2020-05-18 18:02 ` [PATCH 07/23] docs: trace: coresight-ect.rst: Fix a build warning Mathieu Poirier
2020-05-18 18:02 ` [PATCH 08/23] coresight: etm4x: Add support for Qualcomm SC7180 SoC Mathieu Poirier
2020-05-18 18:02 ` [PATCH 09/23] coresight: etm4x: Replace ETM PIDs with UCI IDs for Kryo385 Mathieu Poirier
2020-05-18 18:02 ` [PATCH 10/23] coresight: cti: Make some symbols static Mathieu Poirier
2020-05-18 18:02 ` [PATCH 11/23] coresight: etb10: Make coresight_etb_groups static Mathieu Poirier
2020-05-18 18:02 ` [PATCH 12/23] coresight: Fix support for sparsely populated ports Mathieu Poirier
2020-05-18 18:02 ` [PATCH 13/23] coresight: tmc: Fix TMC mode read in tmc_read_prepare_etb() Mathieu Poirier
2020-05-18 18:02 ` [PATCH 14/23] coresight: etmv4: Update default filter and initialisation Mathieu Poirier
2020-05-18 18:02 ` [PATCH 15/23] coresight: etm4x: Add support for Neoverse N1 ETM Mathieu Poirier
2020-05-18 18:02 ` [PATCH 16/23] coresight: Mark some functions static Mathieu Poirier
2020-05-18 18:02 ` [PATCH 17/23] coresight: Don't initialize variables unnecessarily Mathieu Poirier
2020-05-18 18:02 ` [PATCH 18/23] coresight: Initialize arg in sparse friendly way Mathieu Poirier
2020-05-18 18:02 ` [PATCH 19/23] coresight: Include required headers in C files Mathieu Poirier
2020-05-18 18:02 ` [PATCH 20/23] coresight: Avoid casting void pointers Mathieu Poirier
2020-05-18 18:02 ` [PATCH 21/23] coresight: etm4x: Fix use-after-free of per-cpu etm drvdata Mathieu Poirier
2020-05-19 14:32   ` Greg KH
2020-05-18 18:02 ` [PATCH 22/23] coresight: cti: Add CPU Hotplug handling to CTI driver Mathieu Poirier
2020-05-18 18:02 ` [PATCH 23/23] coresight: cti: Add CPU idle pm notifer to CTI devices Mathieu Poirier

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