[v3,3/6] coresight: Add generic sysfs link creation functions.
diff mbox series

Message ID 20191213145431.24067-4-mike.leach@linaro.org
State New
Headers show
Series
  • Describe CoreSight topology using sysfs links.
Related show

Commit Message

Mike Leach Dec. 13, 2019, 2:54 p.m. UTC
To allow the connections between coresight components to be represented
in sysfs, generic methods for creating sysfs links between two coresight
devices are added.

Signed-off-by: Mike Leach <mike.leach@linaro.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
---
 drivers/hwtracing/coresight/Makefile          |   3 +-
 drivers/hwtracing/coresight/coresight-priv.h  |   4 +
 drivers/hwtracing/coresight/coresight-sysfs.c | 124 ++++++++++++++++++
 include/linux/coresight.h                     |  20 +++
 4 files changed, 150 insertions(+), 1 deletion(-)
 create mode 100644 drivers/hwtracing/coresight/coresight-sysfs.c

Patch
diff mbox series

diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
index 0e3e72f0f510..19497d1d92bf 100644
--- a/drivers/hwtracing/coresight/Makefile
+++ b/drivers/hwtracing/coresight/Makefile
@@ -2,7 +2,8 @@ 
 #
 # Makefile for CoreSight drivers.
 #
-obj-$(CONFIG_CORESIGHT) += coresight.o coresight-etm-perf.o coresight-platform.o
+obj-$(CONFIG_CORESIGHT) += coresight.o coresight-etm-perf.o \
+			   coresight-platform.o coresight-sysfs.o
 obj-$(CONFIG_CORESIGHT_LINK_AND_SINK_TMC) += coresight-tmc.o \
 					     coresight-tmc-etf.o \
 					     coresight-tmc-etr.o
diff --git a/drivers/hwtracing/coresight/coresight-priv.h b/drivers/hwtracing/coresight/coresight-priv.h
index 1cad642f27aa..a4a658d46045 100644
--- a/drivers/hwtracing/coresight/coresight-priv.h
+++ b/drivers/hwtracing/coresight/coresight-priv.h
@@ -153,6 +153,10 @@  struct coresight_device *coresight_get_sink_by_id(u32 id);
 struct list_head *coresight_build_path(struct coresight_device *csdev,
 				       struct coresight_device *sink);
 void coresight_release_path(struct list_head *path);
+int coresight_add_sysfs_link(struct coresight_sysfs_link *info);
+void coresight_remove_sysfs_link(struct coresight_sysfs_link *info);
+int coresight_create_conns_sysfs_group(struct coresight_device *csdev);
+void coresight_remove_conns_sysfs_group(struct coresight_device *csdev);
 
 #ifdef CONFIG_CORESIGHT_SOURCE_ETM3X
 extern int etm_readl_cp14(u32 off, unsigned int *val);
diff --git a/drivers/hwtracing/coresight/coresight-sysfs.c b/drivers/hwtracing/coresight/coresight-sysfs.c
new file mode 100644
index 000000000000..17d565941e5e
--- /dev/null
+++ b/drivers/hwtracing/coresight/coresight-sysfs.c
@@ -0,0 +1,124 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019, Linaro Limited, All rights reserved.
+ * Author: Mike Leach <mike.leach@linaro.org>
+ */
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+
+#include "coresight-priv.h"
+
+/*
+ * Connections group - links attribute.
+ * Count of created links between coresight components in the group.
+ */
+static ssize_t nr_links_show(struct device *dev,
+			     struct device_attribute *attr,
+			     char *buf)
+{
+	struct coresight_device *csdev = to_coresight_device(dev);
+
+	return scnprintf(buf, PAGE_SIZE, "%d\n", csdev->nr_links);
+}
+static DEVICE_ATTR_RO(nr_links);
+
+static struct attribute *coresight_conns_attrs[] = {
+	&dev_attr_nr_links.attr,
+	NULL,
+};
+
+static struct attribute_group coresight_conns_group = {
+	.attrs = coresight_conns_attrs,
+	.name = "connections",
+};
+
+/*
+ * Create connections group for CoreSight devices.
+ * This group will then be used to collate the sysfs links between
+ * devices.
+ */
+int coresight_create_conns_sysfs_group(struct coresight_device *csdev)
+{
+	int ret = 0;
+
+	if (!csdev)
+		return -EINVAL;
+
+	ret = sysfs_create_group(&csdev->dev.kobj, &coresight_conns_group);
+	if (ret)
+		return ret;
+
+	csdev->has_conns_grp = true;
+	return ret;
+}
+
+void coresight_remove_conns_sysfs_group(struct coresight_device *csdev)
+{
+	if (!csdev)
+		return;
+
+	if (csdev->has_conns_grp) {
+		sysfs_remove_group(&csdev->dev.kobj, &coresight_conns_group);
+		csdev->has_conns_grp = false;
+	}
+}
+
+int coresight_add_sysfs_link(struct coresight_sysfs_link *info)
+{
+	int ret = 0;
+
+	if (!info)
+		return -EINVAL;
+	if (!info->orig || !info->target ||
+	    !info->orig_name || !info->target_name)
+		return -EINVAL;
+	if (!info->orig->has_conns_grp || !info->target->has_conns_grp)
+		return -EINVAL;
+
+	/* first link orig->target */
+	ret = sysfs_add_link_to_group(&info->orig->dev.kobj,
+				      coresight_conns_group.name,
+				      &info->target->dev.kobj,
+				      info->orig_name);
+	if (ret)
+		return ret;
+
+	/* second link target->orig */
+	ret = sysfs_add_link_to_group(&info->target->dev.kobj,
+				      coresight_conns_group.name,
+				      &info->orig->dev.kobj,
+				      info->target_name);
+
+	/* error in second link - remove first - otherwise inc counts */
+	if (ret) {
+		sysfs_remove_link_from_group(&info->orig->dev.kobj,
+					     coresight_conns_group.name,
+					     info->orig_name);
+	} else {
+		info->orig->nr_links++;
+		info->target->nr_links++;
+	}
+
+	return ret;
+}
+
+void coresight_remove_sysfs_link(struct coresight_sysfs_link *info)
+{
+	if (!info)
+		return;
+	if (!info->orig || !info->target ||
+	    !info->orig_name || !info->target_name)
+		return;
+
+	sysfs_remove_link_from_group(&info->orig->dev.kobj,
+				     coresight_conns_group.name,
+				     info->orig_name);
+
+	sysfs_remove_link_from_group(&info->target->dev.kobj,
+				     coresight_conns_group.name,
+				     info->target_name);
+
+	info->orig->nr_links--;
+	info->target->nr_links--;
+}
diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index 193cc9dbf448..a2ec25e02ca9 100644
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h
@@ -148,6 +148,20 @@  struct coresight_connection {
 	struct coresight_device *child_dev;
 };
 
+/**
+ * struct coresight_sysfs_link - representation of a connection in sysfs.
+ * @orig:		Originating (master) coresight device for the link.
+ * @orig_name:		Name to use for the link orig->target.
+ * @target:		Target (slave) coresight device for the link.
+ * @target_name:	Name to use for the link target->orig.
+ */
+struct coresight_sysfs_link {
+	struct coresight_device *orig;
+	const char *orig_name;
+	struct coresight_device *target;
+	const char *target_name;
+};
+
 /**
  * struct coresight_device - representation of a device as used by the framework
  * @pdata:	Platform data with device connections associated to this device.
@@ -165,6 +179,9 @@  struct coresight_connection {
  * @ea:		Device attribute for sink representation under PMU directory.
  * @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
+ *		device. These will appear in the "connections" group.
+ * @has_conns_grp: Have added a "connections" group for sysfs links.
  */
 struct coresight_device {
 	struct coresight_platform_data *pdata;
@@ -180,6 +197,9 @@  struct coresight_device {
 	struct dev_ext_attribute *ea;
 	/* cross trigger handling */
 	struct coresight_device *ect_dev;
+	/* sysfs links between components */
+	int nr_links;
+	bool has_conns_grp;
 };
 
 /*