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-rw-r--r--drivers/hwtracing/coresight/coresight-sysfs.c206
1 files changed, 206 insertions, 0 deletions
diff --git a/drivers/hwtracing/coresight/coresight-sysfs.c b/drivers/hwtracing/coresight/coresight-sysfs.c
new file mode 100644
index 000000000..34d2a2d31
--- /dev/null
+++ b/drivers/hwtracing/coresight/coresight-sysfs.c
@@ -0,0 +1,206 @@
+// 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 sprintf(buf, "%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;
+}
+EXPORT_SYMBOL_GPL(coresight_add_sysfs_link);
+
+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--;
+}
+EXPORT_SYMBOL_GPL(coresight_remove_sysfs_link);
+
+/*
+ * coresight_make_links: Make a link for a connection from a @orig
+ * device to @target, represented by @conn.
+ *
+ * e.g, for devOrig[output_X] -> devTarget[input_Y] is represented
+ * as two symbolic links :
+ *
+ * /sys/.../devOrig/out:X -> /sys/.../devTarget/
+ * /sys/.../devTarget/in:Y -> /sys/.../devOrig/
+ *
+ * The link names are allocated for a device where it appears. i.e, the
+ * "out" link on the master and "in" link on the slave device.
+ * The link info is stored in the connection record for avoiding
+ * the reconstruction of names for removal.
+ */
+int coresight_make_links(struct coresight_device *orig,
+ struct coresight_connection *conn,
+ struct coresight_device *target)
+{
+ int ret = -ENOMEM;
+ char *outs = NULL, *ins = NULL;
+ struct coresight_sysfs_link *link = NULL;
+
+ do {
+ outs = devm_kasprintf(&orig->dev, GFP_KERNEL,
+ "out:%d", conn->outport);
+ if (!outs)
+ break;
+ ins = devm_kasprintf(&target->dev, GFP_KERNEL,
+ "in:%d", conn->child_port);
+ if (!ins)
+ break;
+ link = devm_kzalloc(&orig->dev,
+ sizeof(struct coresight_sysfs_link),
+ GFP_KERNEL);
+ if (!link)
+ break;
+
+ link->orig = orig;
+ link->target = target;
+ link->orig_name = outs;
+ link->target_name = ins;
+
+ ret = coresight_add_sysfs_link(link);
+ if (ret)
+ break;
+
+ conn->link = link;
+
+ /*
+ * Install the device connection. This also indicates that
+ * the links are operational on both ends.
+ */
+ conn->child_dev = target;
+ return 0;
+ } while (0);
+
+ return ret;
+}
+
+/*
+ * coresight_remove_links: Remove the sysfs links for a given connection @conn,
+ * from @orig device to @target device. See coresight_make_links() for more
+ * details.
+ */
+void coresight_remove_links(struct coresight_device *orig,
+ struct coresight_connection *conn)
+{
+ if (!orig || !conn->link)
+ return;
+
+ coresight_remove_sysfs_link(conn->link);
+
+ devm_kfree(&conn->child_dev->dev, conn->link->target_name);
+ devm_kfree(&orig->dev, conn->link->orig_name);
+ devm_kfree(&orig->dev, conn->link);
+ conn->link = NULL;
+ conn->child_dev = NULL;
+}