Re: [PATCH v5 3/4] coresight: Add support for trace filtering by source

[Tao Zhang <quic_taozha@xxxxxxxxxxx>]

On 11/13/2024 9:39 PM, Suzuki K Poulose wrote:
> On 30/10/2024 09:32, Tao Zhang wrote:
> > Some replicators have hard coded filtering of "trace" data, based on the
> > source device. This is different from the trace filtering based on
> > TraceID, available in the standard programmable replicators. e.g.,
> > Qualcomm replicators have filtering based on custom trace protocol
> > format and is not programmable.
> >
> > The source device could be connected to the replicator via intermediate
> > components (e.g., a funnel). Thus we need platform information from
> > the firmware tables to decide the source device corresponding to a
> > given output port from the replicator. Given this affects "trace
> > path building" and traversing the path back from the sink to source,
> > add the concept of "filtering by source" to the generic coresight
> > connection.
> >
> > The specified source will be marked like below in the Devicetree.
> > test-replicator {
> >      ... ... ... ...
> >      out-ports {
> >          ... ... ... ...
> >          port@0 {
> >              reg = <0>;
> >              xyz: endpoint {
> >                  remote-endpoint = <&zyx>;
> >                  filter-source = <&source_1>; <-- To specify the 
> > source to
> >              };                           be filtered out here.
> >          };
> >
> >          port@1 {
> >              reg = <1>;
> >              abc: endpoint {
> >                  remote-endpoint = <&cba>;
> >                  filter-source = <&source_2>; <-- To specify the 
> > source to
> >              };                           be filtered out here.
> >          };
> >      };
> > };
> >
> > Signed-off-by: Tao Zhang <quic_taozha@xxxxxxxxxxx>
> > ---
> >   drivers/hwtracing/coresight/coresight-core.c  | 113 +++++++++++++++---
> >   .../hwtracing/coresight/coresight-platform.c  |  18 +++
> >   include/linux/coresight.h                     |   5 +
> >   3 files changed, 117 insertions(+), 19 deletions(-)
> >
> > diff --git a/drivers/hwtracing/coresight/coresight-core.c 
> > b/drivers/hwtracing/coresight/coresight-core.c
> > index ea38ecf26fcb..0a9380350fb5 100644
> > --- a/drivers/hwtracing/coresight/coresight-core.c
> > +++ b/drivers/hwtracing/coresight/coresight-core.c
> > @@ -75,22 +75,54 @@ 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 (!coresight_is_device_source(csdev))
> > +        return NULL;
> > +
> > +    return csdev;
> > +}
> > +
> > +/**
> > + * coresight_blocks_source - checks whether the connection matches 
> > the source
> > + * of path if connection is bound to specific source.
> > + * @src:    The source device of the trace path
> > + * @conn:    The connection of one outport
> > + *
> > + * Return false if the connection doesn't have a source binded or 
> > source of the
> > + * path matches the source binds to connection.
> > + */
> > +static bool coresight_blocks_source(struct coresight_device *src,
> > +                    struct coresight_connection *conn)
> > +{
> > +    return conn->filter_src_fwnode && (conn->filter_src_dev != src);
> > +}
> > +
> >   static struct coresight_connection *
> > -coresight_find_out_connection(struct coresight_device *src_dev,
> > -                  struct coresight_device *dest_dev)
> > +coresight_find_out_connection(struct coresight_device *csdev,
> > +                  struct coresight_device *out_dev,
> > +                  struct coresight_device *trace_src)
> >   {
> >       int i;
> >       struct coresight_connection *conn;
> >   -    for (i = 0; i < src_dev->pdata->nr_outconns; i++) {
> > -        conn = src_dev->pdata->out_conns[i];
> > -        if (conn->dest_dev == dest_dev)
> > +    for (i = 0; i < csdev->pdata->nr_outconns; i++) {
> > +        conn = csdev->pdata->out_conns[i];
> > +        if (coresight_blocks_source(trace_src, conn))
> > +            continue;
> > +        if (conn->dest_dev == out_dev)
> >               return conn;
> >       }
> >   -    dev_err(&src_dev->dev,
> > -        "couldn't find output connection, src_dev: %s, dest_dev: %s\n",
> > -        dev_name(&src_dev->dev), dev_name(&dest_dev->dev));
> > +    dev_err(&csdev->dev,
> > +        "couldn't find output connection, csdev: %s, out_dev: %s\n",
> > +        dev_name(&csdev->dev), dev_name(&out_dev->dev));
> >         return ERR_PTR(-ENODEV);
> >   }
> > @@ -251,7 +283,8 @@ 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 coresight_device *source)
> >   {
> >       int link_subtype;
> >       struct coresight_connection *inconn, *outconn;
> > @@ -259,8 +292,8 @@ 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, source);
> > +    outconn = coresight_find_out_connection(csdev, child, source);
> >       link_subtype = csdev->subtype.link_subtype;
> >         if (link_subtype == CORESIGHT_DEV_SUBTYPE_LINK_MERG && 
> > IS_ERR(inconn))
> > @@ -273,15 +306,16 @@ 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 coresight_device *source)
> >   {
> >       struct coresight_connection *inconn, *outconn;
> >         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, source);
> > +    outconn = coresight_find_out_connection(csdev, child, source);
> >         link_ops(csdev)->disable(csdev, inconn, outconn);
> >   }
> > @@ -375,7 +409,8 @@ 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,
> > +                           coresight_get_source(path));
> >               break;
> >           default:
> >               break;
> > @@ -418,7 +453,9 @@ int coresight_enable_path(struct list_head *path, 
> > enum cs_mode mode,
> >       u32 type;
> >       struct coresight_node *nd;
> >       struct coresight_device *csdev, *parent, *child;
> > +    struct coresight_device *source;
> >   +    source = coresight_get_source(path);
> >       list_for_each_entry_reverse(nd, path, link) {
> >           csdev = nd->csdev;
> >           type = csdev->type;
> > @@ -456,7 +493,7 @@ 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, source);
> >               if (ret)
> >                   goto err;
> >               break;
> > @@ -619,6 +656,7 @@ static void coresight_drop_device(struct 
> > coresight_device *csdev)
> >   /**
> >    * _coresight_build_path - recursively build a path from a @csdev 
> > to a sink.
> >    * @csdev:    The device to start from.
> > + * @source:    The trace source device of the path.
> >    * @sink:    The final sink we want in this path.
> >    * @path:    The list to add devices to.
> >    *
> > @@ -628,6 +666,7 @@ static void coresight_drop_device(struct 
> > coresight_device *csdev)
> >    * the source is the first device and the sink the last one.
> >    */
> >   static int _coresight_build_path(struct coresight_device *csdev,
> > +                 struct coresight_device *source,
> >                    struct coresight_device *sink,
> >                    struct list_head *path)
> >   {
> > @@ -641,7 +680,7 @@ 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, source, sink, path) == 0) {
> >               found = true;
> >               goto out;
> >           }
> > @@ -652,8 +691,12 @@ static int _coresight_build_path(struct 
> > coresight_device *csdev,
> >           struct coresight_device *child_dev;
> >             child_dev = csdev->pdata->out_conns[i]->dest_dev;
> > +
> > +        if (coresight_blocks_source(source, 
> > csdev->pdata->out_conns[i]))
> > +            continue;
> > +
> >           if (child_dev &&
> > -            _coresight_build_path(child_dev, sink, path) == 0) {
> > +            _coresight_build_path(child_dev, source, sink, path) == 
> > 0) {
> >               found = true;
> >               break;
> >           }
> > @@ -698,7 +741,7 @@ 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, source, sink, path);
> >       if (rc) {
> >           kfree(path);
> >           return ERR_PTR(rc);
> > @@ -927,6 +970,16 @@ static int coresight_orphan_match(struct device 
> > *dev, void *data)
> >       for (i = 0; i < src_csdev->pdata->nr_outconns; i++) {
> >           conn = src_csdev->pdata->out_conns[i];
> >   +        /* Fix filter source device before skip the port */
> > +        if (conn->filter_src_fwnode && !conn->filter_src_dev) {
> > +            if (dst_csdev &&
> > +                (conn->filter_src_fwnode == dst_csdev->dev.fwnode) &&
> > + !WARN_ON_ONCE(!coresight_is_device_source(dst_csdev)))
> > +                conn->filter_src_dev = dst_csdev;
> > +            else
> > +                still_orphan = true;
> > +        }
> > +
> >           /* Skip the port if it's already connected. */
> >           if (conn->dest_dev)
> >               continue;
> > @@ -977,18 +1030,40 @@ static int coresight_fixup_orphan_conns(struct 
> > coresight_device *csdev)
> >                csdev, coresight_orphan_match);
> >   }
> >   +static int coresight_clear_filter_source(struct device *dev, void 
> > *data)
> > +{
> > +    int i;
> > +    struct coresight_device *source = data;
> > +    struct coresight_device *csdev = to_coresight_device(dev);
> > +
> > +    for (i = 0; i < csdev->pdata->nr_outconns; ++i) {
> > +        if (csdev->pdata->out_conns[i]->filter_src_dev == source)
> > +            csdev->pdata->out_conns[i]->filter_src_dev = NULL;
> > +    }
> > +    return 0;
> > +}
> > +
> >   /* coresight_remove_conns - Remove other device's references to 
> > this device */
> >   static void coresight_remove_conns(struct coresight_device *csdev)
> >   {
> >       int i, j;
> >       struct coresight_connection *conn;
> >   +    if (coresight_is_device_source(csdev))
> > +        bus_for_each_dev(&coresight_bustype, NULL, csdev,
> > +                 coresight_clear_filter_source);
> > +
> >       /*
> >        * Remove the input connection references from the destination 
> > device
> >        * for each output connection.
> >        */
> >       for (i = 0; i < csdev->pdata->nr_outconns; i++) {
> >           conn = csdev->pdata->out_conns[i];
> > +        if (conn->filter_src_fwnode) {
> > +            conn->filter_src_dev = NULL;
> > +            fwnode_handle_put(conn->filter_src_fwnode);
> > +        }
> > +
> >           if (!conn->dest_dev)
> >               continue;
> >   diff --git a/drivers/hwtracing/coresight/coresight-platform.c 
> > b/drivers/hwtracing/coresight/coresight-platform.c
> > index 64e171eaad82..d5532caa9e92 100644
> > --- a/drivers/hwtracing/coresight/coresight-platform.c
> > +++ b/drivers/hwtracing/coresight/coresight-platform.c
> > @@ -243,6 +243,24 @@ static int of_coresight_parse_endpoint(struct 
> > device *dev,
> >           conn.dest_fwnode = fwnode_handle_get(rdev_fwnode);
> >           conn.dest_port = rendpoint.port;
> >   +        /*
> > +         * Get the firmware node of the filter source through the
> > +         * reference. This could be used to filter the source in
> > +         * building path.
> > +         */
> > +        conn.filter_src_fwnode =
> > +            fwnode_find_reference(&ep->fwnode, "filter-source", 0);
> > +        if (IS_ERR(conn.filter_src_fwnode)) {
> > +            conn.filter_src_fwnode = NULL;
> > +        } else {
> > +            conn.filter_src_dev =
> > + coresight_find_csdev_by_fwnode(conn.filter_src_fwnode);
> > +            if (conn.filter_src_dev &&
> > + !coresight_is_device_source(conn.filter_src_dev))
> > +                dev_warn(&conn.filter_src_dev->dev,
> > +                  "Filter source is not a source device\n");
>
> Do we need to reset the conn.filter_src_fwnode ? Otherwise, we can 
> warn from other places too.

Agree, we need to reset conn.filter_src_fwnode and conn.filter_src_dev 
here if it is not a SOURCE

type device.

I will update the following code to the next patch series. Could you 
help check if it is fine to you?

+            if (conn.filter_src_dev &&
+                !coresight_is_device_source(conn.filter_src_dev)) {
+                dev_warn(&conn.filter_src_dev->dev,
+                  "Filter source is not a source device\n");
+                conn.filter_src_dev = NULL；
+                conn.filter_src_dev = NULL；
+            }

Best,

Tao

> Suzuki
>
> > +        }
> > +
> >           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 9311df8538fc..f372c01ae2fc 100644
> > --- a/include/linux/coresight.h
> > +++ b/include/linux/coresight.h
> > @@ -172,6 +172,9 @@ struct coresight_desc {
> >    * @dest_dev:    a @coresight_device representation of the component
> >           connected to @src_port. NULL until the device is created
> >    * @link: Representation of the connection as a sysfs link.
> > + * @filter_src_fwnode: filter source component's fwnode handle.
> > + * @filter_src_dev: a @coresight_device representation of the 
> > component that
> > +        needs to be filtered.
> >    *
> >    * The full connection structure looks like this, where in_conns store
> >    * references to same connection as the source device's out_conns.
> > @@ -200,6 +203,8 @@ struct coresight_connection {
> >       struct coresight_device *dest_dev;
> >       struct coresight_sysfs_link *link;
> >       struct coresight_device *src_dev;
> > +    struct fwnode_handle *filter_src_fwnode;
> > +    struct coresight_device *filter_src_dev;
> >       atomic_t src_refcnt;
> >       atomic_t dest_refcnt;
> >   };