[PATCH 2/7] coresight: perf: Add "sinks" group to PMU directory

[Mathieu Poirier]

Add a "sinks" directory entry so that users can see all the sinks
available in the system in a single place.  Individual sink are added
as they are registered with the coresight bus.

Signed-off-by: Mathieu Poirier <mathieu.poir...@linaro.org>
---
 .../hwtracing/coresight/coresight-etm-perf.c  | 43 +++++++++++++++++++
 .../hwtracing/coresight/coresight-etm-perf.h  |  1 +
 drivers/hwtracing/coresight/coresight.c       | 17 ++++++++
 3 files changed, 61 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c 
b/drivers/hwtracing/coresight/coresight-etm-perf.c
index f21eb28b6782..292bd409a68c 100644
--- a/drivers/hwtracing/coresight/coresight-etm-perf.c
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
@@ -14,6 +14,7 @@
 #include <linux/perf_event.h>
 #include <linux/percpu-defs.h>
 #include <linux/slab.h>
+#include <linux/stringhash.h>
 #include <linux/types.h>
 #include <linux/workqueue.h>
 
@@ -43,8 +44,18 @@ static const struct attribute_group etm_pmu_format_group = {
        .attrs  = etm_config_formats_attr,
 };
 
+static struct attribute *etm_config_sinks_attr[] = {
+       NULL,
+};
+
+static const struct attribute_group etm_pmu_sinks_group = {
+       .name   = "sinks",
+       .attrs  = etm_config_sinks_attr,
+};
+
 static const struct attribute_group *etm_pmu_attr_groups[] = {
        &etm_pmu_format_group,
+       &etm_pmu_sinks_group,
        NULL,
 };
 
@@ -479,6 +490,38 @@ int etm_perf_symlink(struct coresight_device *csdev, bool 
link)
        return 0;
 }
 
+static ssize_t etm_perf_sink_name_show(struct device *dev,
+                                      struct device_attribute *dattr,
+                                      char *buf)
+{
+       /* See function coresight_sink_by_id() to know where this is used */
+       u32 hash = hashlen_hash(hashlen_string(NULL, dattr->attr.name));
+
+       return scnprintf(buf, PAGE_SIZE, "%x\n", hash);
+}
+
+int etm_perf_symlink_sink(struct coresight_device *csdev)
+{
+       struct device *pmu_dev = etm_pmu.dev;
+       struct device *pdev = csdev->dev.parent;
+       struct device_attribute *dev_attr;
+
+       if (csdev->type != CORESIGHT_DEV_TYPE_SINK &&
+           csdev->type != CORESIGHT_DEV_TYPE_LINKSINK)
+               return -EINVAL;
+
+       if (!etm_perf_up)
+               return -EPROBE_DEFER;
+
+       dev_attr = kzalloc(sizeof(*dev_attr), GFP_KERNEL);
+       dev_attr->attr.name = kstrdup(dev_name(pdev), GFP_KERNEL);
+       dev_attr->attr.mode = 0444;
+       dev_attr->show = etm_perf_sink_name_show;
+
+       return sysfs_add_file_to_group(&pmu_dev->kobj,
+                                      &dev_attr->attr, "sinks");
+}
+
 static int __init etm_perf_init(void)
 {
        int ret;
diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.h 
b/drivers/hwtracing/coresight/coresight-etm-perf.h
index da7d9336a15c..529a47285c0f 100644
--- a/drivers/hwtracing/coresight/coresight-etm-perf.h
+++ b/drivers/hwtracing/coresight/coresight-etm-perf.h
@@ -59,6 +59,7 @@ struct etm_event_data {
 
 #ifdef CONFIG_CORESIGHT
 int etm_perf_symlink(struct coresight_device *csdev, bool link);
+int etm_perf_symlink_sink(struct coresight_device *csdev);
 static inline void *etm_perf_sink_config(struct perf_output_handle *handle)
 {
        struct etm_event_data *data = perf_get_aux(handle);
diff --git a/drivers/hwtracing/coresight/coresight.c 
b/drivers/hwtracing/coresight/coresight.c
index 2b0df1a0a8df..526f122a38ee 100644
--- a/drivers/hwtracing/coresight/coresight.c
+++ b/drivers/hwtracing/coresight/coresight.c
@@ -18,6 +18,7 @@
 #include <linux/delay.h>
 #include <linux/pm_runtime.h>
 
+#include "coresight-etm-perf.h"
 #include "coresight-priv.h"
 
 static DEFINE_MUTEX(coresight_mutex);
@@ -1167,6 +1168,22 @@ struct coresight_device *coresight_register(struct 
coresight_desc *desc)
                goto err_out;
        }
 
+       if (csdev->type == CORESIGHT_DEV_TYPE_SINK ||
+           csdev->type == CORESIGHT_DEV_TYPE_LINKSINK) {
+               ret = etm_perf_symlink_sink(csdev);
+
+               if (ret) {
+                       device_unregister(&csdev->dev);
+                       /*
+                        * As with the above, all resources are free'd
+                        * explicitly via coresight_device_release() triggered
+                        * from put_device(), which is in turn called from
+                        * function device_unregister().
+                        */
+                       goto err_out;
+               }
+       }
+
        mutex_lock(&coresight_mutex);
 
        coresight_fixup_device_conns(csdev);
-- 
2.17.1