From 0336bdfd7354edfa3db0e01675b5df224516e3e9 Mon Sep 17 00:00:00 2001 From: Mike Leach Date: Thu, 16 Jul 2020 11:57:43 -0600 Subject: coresight: Add default sink selection to CoreSight base 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 Suggested-by: Suzuki K Poulose Reviewed-by: Leo Yan Reviewed-by: Suzuki K Poulose Signed-off-by: Mathieu Poirier Link: https://lore.kernel.org/r/20200716175746.3338735-15-mathieu.poirier@linaro.org Signed-off-by: Greg Kroah-Hartman --- drivers/hwtracing/coresight/coresight-priv.h | 2 + drivers/hwtracing/coresight/coresight.c | 166 +++++++++++++++++++++++++++ include/linux/coresight.h | 3 + 3 files changed, 171 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..e9c90f2de34a 100644 --- a/drivers/hwtracing/coresight/coresight.c +++ b/drivers/hwtracing/coresight/coresight.c @@ -769,6 +769,171 @@ 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 return_def_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); + } + +return_def_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 CoreSight device subtypes and distance from source + * to select the best sink. + * + * 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; +} + +static int coresight_remove_sink_ref(struct device *dev, void *data) +{ + struct coresight_device *sink = data; + struct coresight_device *source = to_coresight_device(dev); + + if (source->def_sink == sink) + source->def_sink = NULL; + return 0; +} + +/** + * coresight_clear_default_sink: Remove all default sink references to the + * supplied sink. + * + * If supplied device is a sink, then check all the bus devices and clear + * out all the references to this sink from the coresight_device def_sink + * parameter. + * + * @csdev: coresight sink - remove references to this from all sources. + */ +static void coresight_clear_default_sink(struct coresight_device *csdev) +{ + if ((csdev->type == CORESIGHT_DEV_TYPE_SINK) || + (csdev->type == CORESIGHT_DEV_TYPE_LINKSINK)) { + bus_for_each_dev(&coresight_bustype, NULL, csdev, + coresight_remove_sink_ref); + } +} + /** 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. @@ -1358,6 +1523,7 @@ void coresight_unregister(struct coresight_device *csdev) etm_perf_del_symlink_sink(csdev); /* Remove references of that device in the topology */ coresight_remove_conns(csdev); + coresight_clear_default_sink(csdev); coresight_release_platform_data(csdev, csdev->pdata); device_unregister(&csdev->dev); } 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 */ -- cgit v1.2.3