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Commit 3471644e authored by Tingwei Zhang's avatar Tingwei Zhang
Browse files

coresight: add support to enable multiple coresight paths 



Current coresight implementation supports enabling of a
single path. This patch adds support to enable multiple source
to sink paths. We build a path from source to sink when any
source is enabled and store it in a list. When the source is
disabled, we fetch the corresponding path from the list and
decrement the refcount on each device in the path. The device
is disabled if the refcount reaches zero. Don't store path
to coresight data structure of source to avoid unnecessary
change to ABI.

Change-Id: Idd3dcfd0346bdfd39f41ac13e8e53068907c14e4
Signed-off-by: default avatarSatyajit Desai <sadesai@codeaurora.org>
Signed-off-by: default avatarRama Aparna Mallavarapu <aparnam@codeaurora.org>
Signed-off-by: default avatarMulu He <muluhe@codeaurora.org>
Signed-off-by: default avatarTingwei Zhang <tingwei@codeaurora.org>
parent dce2fd46

drivers/hwtracing/coresight/coresight.c

+56 −45
Original line number Diff line number Diff line
@@ -36,18 +36,16 @@ struct coresight_node { 
};



/*

 * When operating Coresight drivers from the sysFS interface, only a single

 * path can exist from a tracer (associated to a CPU) to a sink.

 * struct coresight_path - path from source to sink

 * @path:	Address of path list.

 * @link:	hook to the list.

 */

static DEFINE_PER_CPU(struct list_head *, tracer_path);

struct coresight_path {

	struct list_head *path;

	struct list_head link;

};



/*

 * As of this writing only a single STM can be found in CS topologies.  Since

 * there is no way to know if we'll ever see more and what kind of

 * configuration they will enact, for the time being only define a single path

 * for STM.

 */

static struct list_head *stm_path;

static LIST_HEAD(cs_active_paths);



/*

 * When losing synchronisation a new barrier packet needs to be inserted at the
@@ -247,7 +245,7 @@ static void coresight_disable_sink(struct coresight_device *csdev) 
	ret = sink_ops(csdev)->disable(csdev);

	if (ret)

		return;

	csdev->enable = false;

	csdev->activated = false;

}



static int coresight_enable_link(struct coresight_device *csdev,
@@ -484,6 +482,20 @@ int coresight_enable_path(struct list_head *path, u32 mode, void *sink_data) 
	goto out;

}



static struct coresight_device *coresight_get_source(struct list_head *path)

{

	struct coresight_device *csdev;



	if (!path)

		return NULL;



	csdev = list_first_entry(path, struct coresight_node, link)->csdev;

	if (csdev->type != CORESIGHT_DEV_TYPE_SOURCE)

		return NULL;



	return csdev;

}



struct coresight_device *coresight_get_sink(struct list_head *path)

{

	struct coresight_device *csdev;
@@ -756,9 +768,23 @@ static int coresight_validate_source(struct coresight_device *csdev, 
	return 0;

}



static int coresight_store_path(struct list_head *path)

{

	struct coresight_path *node;



	node = kzalloc(sizeof(struct coresight_path), GFP_KERNEL);

	if (!node)

		return -ENOMEM;



	node->path = path;

	list_add(&node->link, &cs_active_paths);



	return 0;

}



int coresight_enable(struct coresight_device *csdev)

{

	int cpu, ret = 0;

	int ret = 0;

	struct coresight_device *sink;

	struct list_head *path;

	enum coresight_dev_subtype_source subtype;
@@ -807,25 +833,9 @@ int coresight_enable(struct coresight_device *csdev) 
	if (ret)

		goto err_source;



	switch (subtype) {

	case CORESIGHT_DEV_SUBTYPE_SOURCE_PROC:

		/*

		 * When working from sysFS it is important to keep track

		 * of the paths that were created so that they can be

		 * undone in 'coresight_disable()'.  Since there can only

		 * be a single session per tracer (when working from sysFS)

		 * a per-cpu variable will do just fine.

		 */

		cpu = source_ops(csdev)->cpu_id(csdev);

		per_cpu(tracer_path, cpu) = path;

		break;

	case CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE:

		stm_path = path;

		break;

	default:

		/* We can't be here */

		break;

	}

	ret = coresight_store_path(path);

	if (ret)

		goto err_source;



out:

	mutex_unlock(&coresight_mutex);
@@ -842,8 +852,11 @@ EXPORT_SYMBOL_GPL(coresight_enable); 


void coresight_disable(struct coresight_device *csdev)

{

	int cpu, ret;

	int  ret;

	struct list_head *path = NULL;

	struct coresight_path *cspath = NULL;

	struct coresight_path *cspath_next = NULL;

	struct coresight_device *src_csdev = NULL;



	mutex_lock(&coresight_mutex);
@@ -854,20 +867,18 @@ void coresight_disable(struct coresight_device *csdev) 
	if (!csdev->enable || !coresight_disable_source(csdev))

		goto out;



	switch (csdev->subtype.source_subtype) {

	case CORESIGHT_DEV_SUBTYPE_SOURCE_PROC:

		cpu = source_ops(csdev)->cpu_id(csdev);

		path = per_cpu(tracer_path, cpu);

		per_cpu(tracer_path, cpu) = NULL;

		break;

	case CORESIGHT_DEV_SUBTYPE_SOURCE_SOFTWARE:

		path = stm_path;

		stm_path = NULL;

		break;

	default:

		/* We can't be here */

		break;

	list_for_each_entry_safe(cspath, cspath_next, &cs_active_paths, link) {

		src_csdev = coresight_get_source(cspath->path);

		if (!src_csdev)

			continue;

		if (src_csdev == csdev) {

			path = cspath->path;

			list_del(&cspath->link);

			kfree(cspath);

		}

	}

	if (path == NULL)

		goto out;



	coresight_disable_path(path);

	coresight_release_path(path);