1 files changed, 142 insertions, 42 deletions

diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
index 3e07fd335f8c..2b0df1a0a8df 100644
--- a/drivers/hwtracing/coresight/coresight.c
+++ b/drivers/hwtracing/coresight/coresight.c
@@ -128,16 +128,105 @@ static int coresight_find_link_outport(struct coresight_device *csdev,
 	return -ENODEV;
 }
 
-static int coresight_enable_sink(struct coresight_device *csdev, u32 mode)
+static inline u32 coresight_read_claim_tags(void __iomem *base)
+{
+	return readl_relaxed(base + CORESIGHT_CLAIMCLR);
+}
+
+static inline bool coresight_is_claimed_self_hosted(void __iomem *base)
+{
+	return coresight_read_claim_tags(base) == CORESIGHT_CLAIM_SELF_HOSTED;
+}
+
+static inline bool coresight_is_claimed_any(void __iomem *base)
+{
+	return coresight_read_claim_tags(base) != 0;
+}
+
+static inline void coresight_set_claim_tags(void __iomem *base)
+{
+	writel_relaxed(CORESIGHT_CLAIM_SELF_HOSTED, base + CORESIGHT_CLAIMSET);
+	isb();
+}
+
+static inline void coresight_clear_claim_tags(void __iomem *base)
+{
+	writel_relaxed(CORESIGHT_CLAIM_SELF_HOSTED, base + CORESIGHT_CLAIMCLR);
+	isb();
+}
+
+/*
+ * coresight_claim_device_unlocked : Claim the device for self-hosted usage
+ * to prevent an external tool from touching this device. As per PSCI
+ * standards, section "Preserving the execution context" => "Debug and Trace
+ * save and Restore", DBGCLAIM[1] is reserved for Self-hosted debug/trace and
+ * DBGCLAIM[0] is reserved for external tools.
+ *
+ * Called with CS_UNLOCKed for the component.
+ * Returns : 0 on success
+ */
+int coresight_claim_device_unlocked(void __iomem *base)
+{
+	if (coresight_is_claimed_any(base))
+		return -EBUSY;
+
+	coresight_set_claim_tags(base);
+	if (coresight_is_claimed_self_hosted(base))
+		return 0;
+	/* There was a race setting the tags, clean up and fail */
+	coresight_clear_claim_tags(base);
+	return -EBUSY;
+}
+
+int coresight_claim_device(void __iomem *base)
+{
+	int rc;
+
+	CS_UNLOCK(base);
+	rc = coresight_claim_device_unlocked(base);
+	CS_LOCK(base);
+
+	return rc;
+}
+
+/*
+ * coresight_disclaim_device_unlocked : Clear the claim tags for the device.
+ * Called with CS_UNLOCKed for the component.
+ */
+void coresight_disclaim_device_unlocked(void __iomem *base)
+{
+
+	if (coresight_is_claimed_self_hosted(base))
+		coresight_clear_claim_tags(base);
+	else
+		/*
+		 * The external agent may have not honoured our claim
+		 * and has manipulated it. Or something else has seriously
+		 * gone wrong in our driver.
+		 */
+		WARN_ON_ONCE(1);
+}
+
+void coresight_disclaim_device(void __iomem *base)
+{
+	CS_UNLOCK(base);
+	coresight_disclaim_device_unlocked(base);
+	CS_LOCK(base);
+}
+
+static int coresight_enable_sink(struct coresight_device *csdev,
+				 u32 mode, void *data)
 {
 	int ret;
 
-	if (!csdev->enable) {
-		if (sink_ops(csdev)->enable) {
-			ret = sink_ops(csdev)->enable(csdev, mode);
-			if (ret)
-				return ret;
-		}
+	/*
+	 * We need to make sure the "new" session is compatible with the
+	 * existing "mode" of operation.
+	 */
+	if (sink_ops(csdev)->enable) {
+		ret = sink_ops(csdev)->enable(csdev, mode, data);
+		if (ret)
+			return ret;
 		csdev->enable = true;
 	}
 
@@ -184,8 +273,10 @@ static int coresight_enable_link(struct coresight_device *csdev,
 	if (atomic_inc_return(&csdev->refcnt[refport]) == 1) {
 		if (link_ops(csdev)->enable) {
 			ret = link_ops(csdev)->enable(csdev, inport, outport);
-			if (ret)
+			if (ret) {
+				atomic_dec(&csdev->refcnt[refport]);
 				return ret;
+			}
 		}
 	}
 
@@ -274,13 +365,21 @@ static bool coresight_disable_source(struct coresight_device *csdev)
 	return !csdev->enable;
 }
 
-void coresight_disable_path(struct list_head *path)
+/*
+ * coresight_disable_path_from : Disable components in the given path beyond
+ * @nd in the list. If @nd is NULL, all the components, except the SOURCE are
+ * disabled.
+ */
+static void coresight_disable_path_from(struct list_head *path,
+					struct coresight_node *nd)
 {
 	u32 type;
-	struct coresight_node *nd;
 	struct coresight_device *csdev, *parent, *child;
 
-	list_for_each_entry(nd, path, link) {
+	if (!nd)
+		nd = list_first_entry(path, struct coresight_node, link);
+
+	list_for_each_entry_continue(nd, path, link) {
 		csdev = nd->csdev;
 		type = csdev->type;
 
@@ -300,7 +399,12 @@ void coresight_disable_path(struct list_head *path)
 			coresight_disable_sink(csdev);
 			break;
 		case CORESIGHT_DEV_TYPE_SOURCE:
-			/* sources are disabled from either sysFS or Perf */
+			/*
+			 * We skip the first node in the path assuming that it
+			 * is the source. So we don't expect a source device in
+			 * the middle of a path.
+			 */
+			WARN_ON(1);
 			break;
 		case CORESIGHT_DEV_TYPE_LINK:
 			parent = list_prev_entry(nd, link)->csdev;
@@ -313,7 +417,12 @@ void coresight_disable_path(struct list_head *path)
 	}
 }
 
-int coresight_enable_path(struct list_head *path, u32 mode)
+void coresight_disable_path(struct list_head *path)
+{
+	coresight_disable_path_from(path, NULL);
+}
+
+int coresight_enable_path(struct list_head *path, u32 mode, void *sink_data)
 {
 
 	int ret = 0;
@@ -338,9 +447,15 @@ int coresight_enable_path(struct list_head *path, u32 mode)
 
 		switch (type) {
 		case CORESIGHT_DEV_TYPE_SINK:
-			ret = coresight_enable_sink(csdev, mode);
+			ret = coresight_enable_sink(csdev, mode, sink_data);
+			/*
+			 * Sink is the first component turned on. If we
+			 * failed to enable the sink, there are no components
+			 * that need disabling. Disabling the path here
+			 * would mean we could disrupt an existing session.
+			 */
 			if (ret)
-				goto err;
+				goto out;
 			break;
 		case CORESIGHT_DEV_TYPE_SOURCE:
 			/* sources are enabled from either sysFS or Perf */
@@ -360,7 +475,7 @@ int coresight_enable_path(struct list_head *path, u32 mode)
 out:
 	return ret;
 err:
-	coresight_disable_path(path);
+	coresight_disable_path_from(path, nd);
 	goto out;
 }
 
@@ -635,7 +750,7 @@ int coresight_enable(struct coresight_device *csdev)
 		goto out;
 	}
 
-	ret = coresight_enable_path(path, CS_MODE_SYSFS);
+	ret = coresight_enable_path(path, CS_MODE_SYSFS, NULL);
 	if (ret)
 		goto err_path;
 
@@ -995,18 +1110,16 @@ postcore_initcall(coresight_init);
 
 struct coresight_device *coresight_register(struct coresight_desc *desc)
 {
-	int i;
 	int ret;
 	int link_subtype;
 	int nr_refcnts = 1;
 	atomic_t *refcnts = NULL;
 	struct coresight_device *csdev;
-	struct coresight_connection *conns = NULL;
 
 	csdev = kzalloc(sizeof(*csdev), GFP_KERNEL);
 	if (!csdev) {
 		ret = -ENOMEM;
-		goto err_kzalloc_csdev;
+		goto err_out;
 	}
 
 	if (desc->type == CORESIGHT_DEV_TYPE_LINK ||
@@ -1022,7 +1135,7 @@ struct coresight_device *coresight_register(struct coresight_desc *desc)
 	refcnts = kcalloc(nr_refcnts, sizeof(*refcnts), GFP_KERNEL);
 	if (!refcnts) {
 		ret = -ENOMEM;
-		goto err_kzalloc_refcnts;
+		goto err_free_csdev;
 	}
 
 	csdev->refcnt = refcnts;
@@ -1030,22 +1143,7 @@ struct coresight_device *coresight_register(struct coresight_desc *desc)
 	csdev->nr_inport = desc->pdata->nr_inport;
 	csdev->nr_outport = desc->pdata->nr_outport;
 
-	/* Initialise connections if there is at least one outport */
-	if (csdev->nr_outport) {
-		conns = kcalloc(csdev->nr_outport, sizeof(*conns), GFP_KERNEL);
-		if (!conns) {
-			ret = -ENOMEM;
-			goto err_kzalloc_conns;
-		}
-
-		for (i = 0; i < csdev->nr_outport; i++) {
-			conns[i].outport = desc->pdata->outports[i];
-			conns[i].child_name = desc->pdata->child_names[i];
-			conns[i].child_port = desc->pdata->child_ports[i];
-		}
-	}
-
-	csdev->conns = conns;
+	csdev->conns = desc->pdata->conns;
 
 	csdev->type = desc->type;
 	csdev->subtype = desc->subtype;
@@ -1062,7 +1160,11 @@ struct coresight_device *coresight_register(struct coresight_desc *desc)
 	ret = device_register(&csdev->dev);
 	if (ret) {
 		put_device(&csdev->dev);
-		goto err_kzalloc_csdev;
+		/*
+		 * All resources are free'd explicitly via
+		 * coresight_device_release(), triggered from put_device().
+		 */
+		goto err_out;
 	}
 
 	mutex_lock(&coresight_mutex);
@@ -1074,11 +1176,9 @@ struct coresight_device *coresight_register(struct coresight_desc *desc)
 
 	return csdev;
 
-err_kzalloc_conns:
-	kfree(refcnts);
-err_kzalloc_refcnts:
+err_free_csdev:
 	kfree(csdev);
-err_kzalloc_csdev:
+err_out:
 	return ERR_PTR(ret);
 }
 EXPORT_SYMBOL_GPL(coresight_register);