[PATCH v19 2/7] coresight: tmc: add create/clean functions for etr_buf_list

[Jie Gan]

Introduce functions for creating and inserting or removing the
etr_buf_node to/from the etr_buf_list.

The byte-cntr functionality requires two etr_buf to receive trace data.
The active etr_buf collects the trace data from source device, while the
byte-cntr reading function accesses the deactivated etr_buf after is
has been filled and synced, transferring data to the userspace.

Reviewed-by: Mike Leach <mike.leach@xxxxxxxxxx>
Signed-off-by: Jie Gan <jie.gan@xxxxxxxxxxxxxxxx>
---
 drivers/hwtracing/coresight/coresight-tmc-core.c |   1 +
 drivers/hwtracing/coresight/coresight-tmc-etr.c  | 126 +++++++++++++++++++++++
 drivers/hwtracing/coresight/coresight-tmc.h      |  17 +++
 3 files changed, 144 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
index bc5a133ada3e..bc7dd676da47 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-core.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
@@ -835,6 +835,7 @@ static int __tmc_probe(struct device *dev, struct resource *res)
 		idr_init(&drvdata->idr);
 		mutex_init(&drvdata->idr_mutex);
 		dev_list = "tmc_etr";
+		INIT_LIST_HEAD(&drvdata->etr_buf_list);
 		break;
 	case TMC_CONFIG_TYPE_ETF:
 		desc.groups = coresight_etf_groups;
diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index 361a433e6f0c..9b3ef73e9cf2 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -1918,6 +1918,132 @@ const struct coresight_ops tmc_etr_cs_ops = {
 	.panic_ops	= &tmc_etr_sync_ops,
 };
 
+/**
+ * tmc_clean_etr_buf_list - clean the etr_buf_list.
+ * @drvdata:	driver data of the TMC device.
+ *
+ * Remove all nodes from @drvdata->etr_buf_list and free their buffers.
+ * If a node holds the live sysfs_buf and the device is active, the node is
+ * removed but the buffer is not freed; ownership stays with drvdata->sysfs_buf.
+ *
+ * Locking: callers must guarantee exclusive access to @drvdata->etr_buf_list
+ * and must not hold @drvdata->spinlock. The spinlock is taken internally only
+ * to serialise the @drvdata->sysfs_buf accesses against the ETR sink
+ * enable/disable paths. Must be called from process context: buffers are freed
+ * with the lock released.
+ */
+void tmc_clean_etr_buf_list(struct tmc_drvdata *drvdata)
+{
+	struct etr_buf_node *nd, *next;
+	unsigned long flags;
+
+	list_for_each_entry_safe(nd, next, &drvdata->etr_buf_list, link) {
+		raw_spin_lock_irqsave(&drvdata->spinlock, flags);
+		if (nd->sysfs_buf == drvdata->sysfs_buf) {
+			if (coresight_get_mode(drvdata->csdev) != CS_MODE_DISABLED)
+				/*
+				 * The device is still active. Keep the live
+				 * buffer owned by drvdata->sysfs_buf and only
+				 * drop the list's reference to it.
+				 */
+				nd->sysfs_buf = NULL;
+			else
+				/* Free the buffer below through nd->sysfs_buf */
+				drvdata->sysfs_buf = NULL;
+		}
+		raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
+
+		/* Free the buffer (NULL is ignored) and the node out of the lock */
+		tmc_etr_free_sysfs_buf(nd->sysfs_buf);
+		list_del(&nd->link);
+		kfree(nd);
+	}
+}
+EXPORT_SYMBOL_GPL(tmc_clean_etr_buf_list);
+
+/**
+ * tmc_create_etr_buf_list - create a list to manage the etr_buf_node.
+ * @drvdata:	driver data of the TMC device.
+ * @num_nodes:	number of nodes want to create with the list.
+ *
+ * Locking: callers must guarantee exclusive access to @drvdata->etr_buf_list
+ * and must not hold @drvdata->spinlock. The spinlock is taken internally only
+ * to serialise the @drvdata->sysfs_buf accesses against the ETR sink
+ * enable/disable paths. Must be called from process context: buffers and nodes
+ * are allocated with the lock released.
+ *
+ * Return 0 upon success and return the error number if fail.
+ */
+int tmc_create_etr_buf_list(struct tmc_drvdata *drvdata, int num_nodes)
+{
+	struct etr_buf_node *new_node;
+	struct etr_buf *sysfs_buf;
+	unsigned long flags;
+	int i = 0, ret = 0;
+
+	/* We don't need a list if there is only one node */
+	if (num_nodes < 2)
+		return -EINVAL;
+
+	/*
+	 * We expect that sysfs_buf in drvdata has already been allocated.
+	 * Wrap the live sysfs_buf into the first node so the captured trace
+	 * data is preserved. The list is owned by the caller, so no lock is
+	 * needed to read sysfs_buf or to add the node here.
+	 */
+	if (drvdata->sysfs_buf) {
+		new_node = kzalloc_obj(*new_node, GFP_KERNEL);
+		if (!new_node)
+			return -ENOMEM;
+
+		new_node->sysfs_buf = drvdata->sysfs_buf;
+		new_node->is_free = false;
+		list_add(&new_node->link, &drvdata->etr_buf_list);
+		i++;
+	}
+
+	while (i < num_nodes) {
+		new_node = kzalloc_obj(*new_node, GFP_KERNEL);
+		if (!new_node) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		/* Allocate the buffer with the lock released */
+		sysfs_buf = tmc_alloc_etr_buf(drvdata, drvdata->size, 0, cpu_to_node(0), NULL);
+		if (IS_ERR(sysfs_buf)) {
+			kfree(new_node);
+			ret = PTR_ERR(sysfs_buf);
+			break;
+		}
+
+		new_node->sysfs_buf = sysfs_buf;
+		/*
+		 * Only the drvdata->sysfs_buf write needs the spinlock, to
+		 * serialise against the ETR sink enable/disable paths.
+		 */
+		raw_spin_lock_irqsave(&drvdata->spinlock, flags);
+		/* We don't have an available sysfs_buf in drvdata, set one up */
+		if (!drvdata->sysfs_buf) {
+			drvdata->sysfs_buf = sysfs_buf;
+			new_node->is_free = false;
+		} else {
+			new_node->is_free = true;
+		}
+		raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
+
+		list_add_tail(&new_node->link, &drvdata->etr_buf_list);
+		i++;
+	}
+
+	/* Clean the list if there is an error */
+	if (ret)
+		tmc_clean_etr_buf_list(drvdata);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(tmc_create_etr_buf_list);
+
 int tmc_read_prepare_etr(struct tmc_drvdata *drvdata)
 {
 	int ret = 0;
diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
index 319a354ede9f..6e994678f926 100644
--- a/drivers/hwtracing/coresight/coresight-tmc.h
+++ b/drivers/hwtracing/coresight/coresight-tmc.h
@@ -208,6 +208,19 @@ struct tmc_resrv_buf {
 	s64		len;
 };
 
+/**
+ * @sysfs_buf:	Allocated sysfs_buf.
+ * @is_free:	Indicates whether the buffer is free to choose.
+ * @pos:	Offset to the start of the buffer.
+ * @link:	list_head of the node.
+ */
+struct etr_buf_node {
+	struct etr_buf		*sysfs_buf;
+	bool			is_free;
+	loff_t			pos;
+	struct list_head	link;
+};
+
 /**
  * struct tmc_drvdata - specifics associated to an TMC component
  * @atclk:	optional clock for the core parts of the TMC.
@@ -245,6 +258,7 @@ struct tmc_resrv_buf {
  *		(after crash) by default.
  * @crash_mdata: Reserved memory for storing tmc crash metadata.
  *		 Used by ETR/ETF.
+ * @etr_buf_list: List that is used to manage allocated etr_buf.
  */
 struct tmc_drvdata {
 	struct clk		*atclk;
@@ -275,6 +289,7 @@ struct tmc_drvdata {
 	struct etr_buf		*perf_buf;
 	struct tmc_resrv_buf	resrv_buf;
 	struct tmc_resrv_buf	crash_mdata;
+	struct list_head        etr_buf_list;
 };
 
 struct etr_buf_operations {
@@ -447,5 +462,7 @@ struct etr_buf *tmc_etr_get_buffer(struct coresight_device *csdev,
 				   enum cs_mode mode,
 				   struct coresight_path *path);
 extern const struct attribute_group coresight_etr_group;
+void tmc_clean_etr_buf_list(struct tmc_drvdata *drvdata);
+int tmc_create_etr_buf_list(struct tmc_drvdata *drvdata, int num_nodes);
 
 #endif

-- 
2.34.1