coresight: cti: Add in sysfs links to other coresight devices

Adds in sysfs links for connections where the connected device is another
coresight device. This allows examination of the coresight topology.

Non-coresight connections remain just as a reference name.

Signed-off-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200518180242.7916-6-mathieu.poirier@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hwtracing/coresight/coresight-cti.c b/drivers/hwtracing/coresight/coresight-cti.c
index aa6e0249bd70e6b22d5672c28615835ee861500a..9e262f5a85e324b6872e9f12f921b4fe2710be01 100644 (file)
--- a/drivers/hwtracing/coresight/coresight-cti.c
+++ b/drivers/hwtracing/coresight/coresight-cti.c
@@ -442,6 +442,34 @@ int cti_channel_setop(struct device *dev, enum cti_chan_set_op op,
        return err;
 }
 
+static bool cti_add_sysfs_link(struct cti_drvdata *drvdata,
+                              struct cti_trig_con *tc)
+{
+       struct coresight_sysfs_link link_info;
+       int link_err = 0;
+
+       link_info.orig = drvdata->csdev;
+       link_info.orig_name = tc->con_dev_name;
+       link_info.target = tc->con_dev;
+       link_info.target_name = dev_name(&drvdata->csdev->dev);
+
+       link_err = coresight_add_sysfs_link(&link_info);
+       if (link_err)
+               dev_warn(&drvdata->csdev->dev,
+                        "Failed to set CTI sysfs link %s<=>%s\n",
+                        link_info.orig_name, link_info.target_name);
+       return !link_err;
+}
+
+static void cti_remove_sysfs_link(struct cti_trig_con *tc)
+{
+       struct coresight_sysfs_link link_info;
+
+       link_info.orig_name = tc->con_dev_name;
+       link_info.target = tc->con_dev;
+       coresight_remove_sysfs_link(&link_info);
+}
+
 /*
  * Look for a matching connection device name in the list of connections.
  * If found then swap in the csdev name, set trig con association pointer
@@ -452,6 +480,8 @@ cti_match_fixup_csdev(struct cti_device *ctidev, const char *node_name,
                      struct coresight_device *csdev)
 {
        struct cti_trig_con *tc;
+       struct cti_drvdata *drvdata = container_of(ctidev, struct cti_drvdata,
+                                                  ctidev);
 
        list_for_each_entry(tc, &ctidev->trig_cons, node) {
                if (tc->con_dev_name) {
@@ -459,7 +489,12 @@ cti_match_fixup_csdev(struct cti_device *ctidev, const char *node_name,
                                /* match: so swap in csdev name & dev */
                                tc->con_dev_name = dev_name(&csdev->dev);
                                tc->con_dev = csdev;
-                               return true;
+                               /* try to set sysfs link */
+                               if (cti_add_sysfs_link(drvdata, tc))
+                                       return true;
+                               /* link failed - remove CTI reference */
+                               tc->con_dev = NULL;
+                               break;
                        }
                }
        }
@@ -522,6 +557,7 @@ void cti_remove_assoc_from_csdev(struct coresight_device *csdev)
                ctidev = &ctidrv->ctidev;
                list_for_each_entry(tc, &ctidev->trig_cons, node) {
                        if (tc->con_dev == csdev->ect_dev) {
+                               cti_remove_sysfs_link(tc);
                                tc->con_dev = NULL;
                                break;
                        }
@@ -543,10 +579,16 @@ static void cti_update_conn_xrefs(struct cti_drvdata *drvdata)
        struct cti_device *ctidev = &drvdata->ctidev;
 
        list_for_each_entry(tc, &ctidev->trig_cons, node) {
-               if (tc->con_dev)
-                       /* set tc->con_dev->ect_dev */
-                       coresight_set_assoc_ectdev_mutex(tc->con_dev,
+               if (tc->con_dev) {
+                       /* if we can set the sysfs link */
+                       if (cti_add_sysfs_link(drvdata, tc))
+                               /* set the CTI/csdev association */
+                               coresight_set_assoc_ectdev_mutex(tc->con_dev,
                                                         drvdata->csdev);
+                       else
+                               /* otherwise remove reference from CTI */
+                               tc->con_dev = NULL;
+               }
        }
 }
 
@@ -559,6 +601,8 @@ static void cti_remove_conn_xrefs(struct cti_drvdata *drvdata)
                if (tc->con_dev) {
                        coresight_set_assoc_ectdev_mutex(tc->con_dev,
                                                         NULL);
+                       cti_remove_sysfs_link(tc);
+                       tc->con_dev = NULL;
                }
        }
 }