Adds a method to select a suitable sink connected to a given source.
In cases where no sink is defined, the coresight_find_default_sink routine can search from a given source, through the child connections until a suitable sink is found.
The suitability is defined in by the sink coresight_dev_subtype on the CoreSight device, and the distance from the source by counting connections.
Higher value subtype is preferred - where these are equal, shorter distance from source is used as a tie-break.
This allows for default sink to be discovered were none is specified (e.g. perf command line)
Signed-off-by: Mike Leach mike.leach@linaro.org --- drivers/hwtracing/coresight/coresight-priv.h | 2 + drivers/hwtracing/coresight/coresight.c | 137 +++++++++++++++++++ include/linux/coresight.h | 3 + 3 files changed, 142 insertions(+)
diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h index 36c943ae94d5..f2dc625ea585 100644 --- a/drivers/hwtracing/coresight/coresight-priv.h +++ b/drivers/hwtracing/coresight/coresight-priv.h @@ -150,6 +150,8 @@ int coresight_enable_path(struct list_head *path, u32 mode, void *sink_data); struct coresight_device *coresight_get_sink(struct list_head *path); struct coresight_device *coresight_get_enabled_sink(bool reset); struct coresight_device *coresight_get_sink_by_id(u32 id); +struct coresight_device * +coresight_find_default_sink(struct coresight_device *csdev); struct list_head *coresight_build_path(struct coresight_device *csdev, struct coresight_device *sink); void coresight_release_path(struct list_head *path); diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c index f3efbb3b2b4d..96b9ad249c62 100644 --- a/drivers/hwtracing/coresight/coresight.c +++ b/drivers/hwtracing/coresight/coresight.c @@ -769,6 +769,143 @@ void coresight_release_path(struct list_head *path) path = NULL; }
+/* return true if the device is a suitable type for a default sink */ +static inline bool coresight_is_def_sink_type(struct coresight_device *csdev) +{ + /* sink & correct subtype */ + if (((csdev->type == CORESIGHT_DEV_TYPE_SINK) || + (csdev->type == CORESIGHT_DEV_TYPE_LINKSINK)) && + (csdev->subtype.sink_subtype >= CORESIGHT_DEV_SUBTYPE_SINK_BUFFER)) + return true; + return false; +} + +/** + * coresight_select_best_sink - return the best sink for use as default from + * the two provided. + * + * @sink: current best sink. + * @depth: search depth where current sink was found. + * @new_sink: new sink for comparison with current sink. + * @new_depth: search depth where new sink was found. + * + * Sinks prioritised according to coresight_dev_subtype_sink, with only + * subtypes CORESIGHT_DEV_SUBTYPE_SINK_BUFFER or higher being used. + * + * Where two sinks of equal priority are found, the sink closest to the + * source is used (smallest search depth). + * + * return @new_sink & update @depth if better than @sink, else return @sink. + */ +static struct coresight_device * +coresight_select_best_sink(struct coresight_device *sink, int *depth, + struct coresight_device *new_sink, int new_depth) +{ + bool update = false; + + if (!sink) { + /* first found at this level */ + update = true; + } else if (new_sink->subtype.sink_subtype > + sink->subtype.sink_subtype) { + /* found better sink */ + update = true; + } else if ((new_sink->subtype.sink_subtype == + sink->subtype.sink_subtype) && + (*depth > new_depth)) { + /* found same but closer sink */ + update = true; + } + + if (update) + *depth = new_depth; + return update ? new_sink : sink; +} + +/** + * coresight_find_sink - recursive function to walk trace connections from + * source to find a suitable default sink. + * + * @csdev: source / current device to check. + * @depth: [in] search depth of calling dev, [out] depth of found sink. + * + * This will walk the connection path from a source (ETM) till a suitable + * sink is encountered and return that sink to the original caller. + * + * If current device is a plain sink return that & depth, otherwise recursively + * call child connections looking for a sink. Select best possible using + * coresight_select_best_sink. + * + * return best sink found, or NULL if not found at this node or child nodes. + */ +static struct coresight_device * +coresight_find_sink(struct coresight_device *csdev, + int *depth) +{ + int i, curr_depth = *depth+1, found_depth = 0; + struct coresight_device *found_sink = NULL; + + if (coresight_is_def_sink_type(csdev)) { + found_depth = curr_depth; + found_sink = csdev; + if (csdev->type == CORESIGHT_DEV_TYPE_SINK) + goto coresight_return_sink; + /* look past LINKSINK for something better */ + } + + /* + * Not a sink we want - or possible child sink may be better. + * recursively explore each port found on this element. + */ + for (i = 0; i < csdev->pdata->nr_outport; i++) { + struct coresight_device *child_dev, *sink = NULL; + int child_depth = curr_depth; + + child_dev = csdev->pdata->conns[i].child_dev; + if (child_dev) + sink = coresight_find_sink(child_dev, &child_depth); + + + if (sink) + found_sink = coresight_select_best_sink(found_sink, + &found_depth, + sink, + child_depth); + } + +coresight_return_sink: + /* return found sink and depth */ + if (found_sink) + *depth = found_depth; + return found_sink; +} + +/** + * coresight_find_default_sink: Find a sink suitable for use as a + * default sink. + * + * @csdev: starting source to find a connected sink. + * + * Walks connections graph looking for a suitable sink to enable for the + * supplied source. Uses csdev->priority values. + * + * If a sink is found, then the default sink for this device is set and + * will be automatically used in future. + * + * Used in cases where the CoreSight user (perf / sysfs) has not selected a + * sink. + */ +struct coresight_device * +coresight_find_default_sink(struct coresight_device *csdev) +{ + int depth = 0; + + /* look for a default sink if we have not found for this device */ + if (!csdev->def_sink) + csdev->def_sink = coresight_find_sink(csdev, &depth); + return csdev->def_sink; +} + /** coresight_validate_source - make sure a source has the right credentials * @csdev: the device structure for a source. * @function: the function this was called from. diff --git a/include/linux/coresight.h b/include/linux/coresight.h index 84dc695e87d4..58fffdecdbfd 100644 --- a/include/linux/coresight.h +++ b/include/linux/coresight.h @@ -48,6 +48,7 @@ enum coresight_dev_subtype_sink { CORESIGHT_DEV_SUBTYPE_SINK_NONE, CORESIGHT_DEV_SUBTYPE_SINK_PORT, CORESIGHT_DEV_SUBTYPE_SINK_BUFFER, + CORESIGHT_DEV_SUBTYPE_SINK_SYSMEM, };
enum coresight_dev_subtype_link { @@ -182,6 +183,7 @@ struct coresight_sysfs_link { * happens when a source has been selected and a path is enabled * from source to that sink. * @ea: Device attribute for sink representation under PMU directory. + * @def_sink: cached reference to default sink found for this device. * @ect_dev: Associated cross trigger device. Not part of the trace data * path or connections. * @nr_links: number of sysfs links created to other components from this @@ -200,6 +202,7 @@ struct coresight_device { /* sink specific fields */ bool activated; /* true only if a sink is part of a path */ struct dev_ext_attribute *ea; + struct coresight_device *def_sink; /* cross trigger handling */ struct coresight_device *ect_dev; /* sysfs links between components */