Re: [PATCH 2/4] coresight: Add support for multiple output ports on the funnel

[Suzuki K Poulose <suzuki.poulose@arm.com>]

On 21/03/2024 08:32, Tao Zhang wrote:
> Funnel devices are now capable of supporting multiple-inputs and
> multiple-outputs configuration with in built hardware filtering
> for TPDM devices. Add software support to this function. Output
> port is selected according to the source in the trace path.
> 
> The source of the input port on funnels will be marked in the
> device tree.
> e.g.
> tpdm@xxxxxxx {
>      ... ... ... ...
> };
> 
> funnel_XXX: funnel@xxxxxxx {
>      ... ... ... ...
>      out-ports {
>          ... ... ... ...
>          port@x {
>              ... ... ... ...
>              label = "xxxxxxx.tpdm"; <-- To label the source
>          };                           corresponding to the output
>      ... ... ... ...                  connection "port@x". And this
>      };                               is a hardware static connections.
>      ... ... ... ...                  Here needs to refer to hardware
> };                                   design.
> 
> Then driver will parse the source label marked in the device tree, and
> save it to the coresight path. When the function needs to know the
> source label, it could obtain it from coresight path parameter. Finally,
> the output port knows which source it corresponds to, and it also knows
> which input port it corresponds to.

Why do we need labels ? We have connection information for all devices
(both in and out), so, why do we need this label to find a device ?

And also, I thought TPDM is a source device, why does a funnel output
port link to a source ?

Are these funnels programmable ? Or, are they static ? If they are
static, do these need to be described in the DT ? If they are simply
acting as a "LINK" (or HWFIFO ?)

Suzuki

> 
> Signed-off-by: Tao Zhang <quic_taozha@quicinc.com>
> ---
>   drivers/hwtracing/coresight/coresight-core.c  | 81 ++++++++++++++++---
>   .../hwtracing/coresight/coresight-platform.c  |  5 ++
>   include/linux/coresight.h                     |  2 +
>   3 files changed, 75 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
> index 5dde597403b3..b1b5e6d9ec7a 100644
> --- a/drivers/hwtracing/coresight/coresight-core.c
> +++ b/drivers/hwtracing/coresight/coresight-core.c
> @@ -113,15 +113,63 @@ struct coresight_device *coresight_get_percpu_sink(int cpu)
>   }
>   EXPORT_SYMBOL_GPL(coresight_get_percpu_sink);
>   
> +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;
> +}
> +
> +/**
> + * coresight_source_filter - checks whether the connection matches the source
> + * of path if connection is binded to specific source.
> + * @path:	The list of devices
> + * @conn:	The connection of one outport
> + *
> + * Return zero if the connection doesn't have a source binded or source of the
> + * path matches the source binds to connection.
> + */
> +static int coresight_source_filter(struct list_head *path,
> +			struct coresight_connection *conn)
> +{
> +	int ret = 0;
> +	struct coresight_device *source = NULL;
> +
> +	if (conn->source_label == NULL)
> +		return ret;
> +
> +	source = coresight_get_source(path);
> +	if (source == NULL)
> +		return ret;
> +
> +	if (strstr(kobject_get_path(&source->dev.kobj, GFP_KERNEL),
> +			conn->source_label))
> +		ret = 0;
> +	else
> +		ret = -1;
> +
> +	return ret;
> +}
> +
>   static struct coresight_connection *
>   coresight_find_out_connection(struct coresight_device *src_dev,
> -			      struct coresight_device *dest_dev)
> +			      struct coresight_device *dest_dev,
> +			      struct list_head *path)
>   {
>   	int i;
>   	struct coresight_connection *conn;
>   
>   	for (i = 0; i < src_dev->pdata->nr_outconns; i++) {
>   		conn = src_dev->pdata->out_conns[i];
> +		if (coresight_source_filter(path, conn))
> +			continue;
>   		if (conn->dest_dev == dest_dev)
>   			return conn;
>   	}
> @@ -312,7 +360,8 @@ static void coresight_disable_sink(struct coresight_device *csdev)
>   
>   static int coresight_enable_link(struct coresight_device *csdev,
>   				 struct coresight_device *parent,
> -				 struct coresight_device *child)
> +				 struct coresight_device *child,
> +				 struct list_head *path)
>   {
>   	int ret = 0;
>   	int link_subtype;
> @@ -321,8 +370,8 @@ static int coresight_enable_link(struct coresight_device *csdev,
>   	if (!parent || !child)
>   		return -EINVAL;
>   
> -	inconn = coresight_find_out_connection(parent, csdev);
> -	outconn = coresight_find_out_connection(csdev, child);
> +	inconn = coresight_find_out_connection(parent, csdev, path);
> +	outconn = coresight_find_out_connection(csdev, child, path);
>   	link_subtype = csdev->subtype.link_subtype;
>   
>   	if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_MERG && IS_ERR(inconn))
> @@ -341,7 +390,8 @@ static int coresight_enable_link(struct coresight_device *csdev,
>   
>   static void coresight_disable_link(struct coresight_device *csdev,
>   				   struct coresight_device *parent,
> -				   struct coresight_device *child)
> +				   struct coresight_device *child,
> +				   struct list_head *path)
>   {
>   	int i;
>   	int link_subtype;
> @@ -350,8 +400,8 @@ static void coresight_disable_link(struct coresight_device *csdev,
>   	if (!parent || !child)
>   		return;
>   
> -	inconn = coresight_find_out_connection(parent, csdev);
> -	outconn = coresight_find_out_connection(csdev, child);
> +	inconn = coresight_find_out_connection(parent, csdev, path);
> +	outconn = coresight_find_out_connection(csdev, child, path);
>   	link_subtype = csdev->subtype.link_subtype;
>   
>   	if (link_ops(csdev)->disable) {
> @@ -507,7 +557,7 @@ static void coresight_disable_path_from(struct list_head *path,
>   		case CORESIGHT_DEV_TYPE_LINK:
>   			parent = list_prev_entry(nd, link)->csdev;
>   			child = list_next_entry(nd, link)->csdev;
> -			coresight_disable_link(csdev, parent, child);
> +			coresight_disable_link(csdev, parent, child, path);
>   			break;
>   		default:
>   			break;
> @@ -588,7 +638,7 @@ int coresight_enable_path(struct list_head *path, enum cs_mode mode,
>   		case CORESIGHT_DEV_TYPE_LINK:
>   			parent = list_prev_entry(nd, link)->csdev;
>   			child = list_next_entry(nd, link)->csdev;
> -			ret = coresight_enable_link(csdev, parent, child);
> +			ret = coresight_enable_link(csdev, parent, child, path);
>   			if (ret)
>   				goto err;
>   			break;
> @@ -802,7 +852,8 @@ static void coresight_drop_device(struct coresight_device *csdev)
>    */
>   static int _coresight_build_path(struct coresight_device *csdev,
>   				 struct coresight_device *sink,
> -				 struct list_head *path)
> +				 struct list_head *path,
> +				 struct coresight_device *source)
>   {
>   	int i, ret;
>   	bool found = false;
> @@ -814,7 +865,7 @@ static int _coresight_build_path(struct coresight_device *csdev,
>   
>   	if (coresight_is_percpu_source(csdev) && coresight_is_percpu_sink(sink) &&
>   	    sink == per_cpu(csdev_sink, source_ops(csdev)->cpu_id(csdev))) {
> -		if (_coresight_build_path(sink, sink, path) == 0) {
> +		if (_coresight_build_path(sink, sink, path, source) == 0) {
>   			found = true;
>   			goto out;
>   		}
> @@ -825,8 +876,12 @@ static int _coresight_build_path(struct coresight_device *csdev,
>   		struct coresight_device *child_dev;
>   
>   		child_dev = csdev->pdata->out_conns[i]->dest_dev;
> +		if (csdev->pdata->out_conns[i]->source_label &&
> +			!strstr(kobject_get_path(&source->dev.kobj, GFP_KERNEL),
> +				csdev->pdata->out_conns[i]->source_label))
> +			continue;
>   		if (child_dev &&
> -		    _coresight_build_path(child_dev, sink, path) == 0) {
> +		    _coresight_build_path(child_dev, sink, path, source) == 0) {
>   			found = true;
>   			break;
>   		}
> @@ -871,7 +926,7 @@ struct list_head *coresight_build_path(struct coresight_device *source,
>   
>   	INIT_LIST_HEAD(path);
>   
> -	rc = _coresight_build_path(source, sink, path);
> +	rc = _coresight_build_path(source, sink, path, source);
>   	if (rc) {
>   		kfree(path);
>   		return ERR_PTR(rc);
> diff --git a/drivers/hwtracing/coresight/coresight-platform.c b/drivers/hwtracing/coresight/coresight-platform.c
> index 9d550f5697fa..f553fb20966d 100644
> --- a/drivers/hwtracing/coresight/coresight-platform.c
> +++ b/drivers/hwtracing/coresight/coresight-platform.c
> @@ -205,6 +205,7 @@ static int of_coresight_parse_endpoint(struct device *dev,
>   	struct fwnode_handle *rdev_fwnode;
>   	struct coresight_connection conn = {};
>   	struct coresight_connection *new_conn;
> +	const char *label;
>   
>   	do {
>   		/* Parse the local port details */
> @@ -243,6 +244,10 @@ static int of_coresight_parse_endpoint(struct device *dev,
>   		conn.dest_fwnode = fwnode_handle_get(rdev_fwnode);
>   		conn.dest_port = rendpoint.port;
>   
> +		conn.source_label = NULL;
> +		if (!of_property_read_string(ep, "label", &label))
> +			conn.source_label = label;
> +
>   		new_conn = coresight_add_out_conn(dev, pdata, &conn);
>   		if (IS_ERR_VALUE(new_conn)) {
>   			fwnode_handle_put(conn.dest_fwnode);
> diff --git a/include/linux/coresight.h b/include/linux/coresight.h
> index e8b6e388218c..a9c06ef9bbb2 100644
> --- a/include/linux/coresight.h
> +++ b/include/linux/coresight.h
> @@ -167,6 +167,7 @@ struct coresight_desc {
>    * struct coresight_connection - representation of a single connection
>    * @src_port:	a connection's output port number.
>    * @dest_port:	destination's input port number @src_port is connected to.
> + * @source_label: source component's label.
>    * @dest_fwnode: destination component's fwnode handle.
>    * @dest_dev:	a @coresight_device representation of the component
>   		connected to @src_port. NULL until the device is created
> @@ -195,6 +196,7 @@ struct coresight_desc {
>   struct coresight_connection {
>   	int src_port;
>   	int dest_port;
> +	const char *source_label;
>   	struct fwnode_handle *dest_fwnode;
>   	struct coresight_device *dest_dev;
>   	struct coresight_sysfs_link *link;