1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (c) 2019, Linaro Limited, All rights reserved.
  4 * Author: Mike Leach <mike.leach@linaro.org>
  5 */
  6
  7#include <linux/device.h>
  8#include <linux/kernel.h>
  9
 10#include "coresight-priv.h"
 11
 12/*
 13 * Connections group - links attribute.
 14 * Count of created links between coresight components in the group.
 15 */
 16static ssize_t nr_links_show(struct device *dev,
 17			     struct device_attribute *attr,
 18			     char *buf)
 19{
 20	struct coresight_device *csdev = to_coresight_device(dev);
 21
 22	return sprintf(buf, "%d\n", csdev->nr_links);
 23}
 24static DEVICE_ATTR_RO(nr_links);
 25
 26static struct attribute *coresight_conns_attrs[] = {
 27	&dev_attr_nr_links.attr,
 28	NULL,
 29};
 30
 31static struct attribute_group coresight_conns_group = {
 32	.attrs = coresight_conns_attrs,
 33	.name = "connections",
 34};
 35
 36/*
 37 * Create connections group for CoreSight devices.
 38 * This group will then be used to collate the sysfs links between
 39 * devices.
 40 */
 41int coresight_create_conns_sysfs_group(struct coresight_device *csdev)
 42{
 43	int ret = 0;
 44
 45	if (!csdev)
 46		return -EINVAL;
 47
 48	ret = sysfs_create_group(&csdev->dev.kobj, &coresight_conns_group);
 49	if (ret)
 50		return ret;
 51
 52	csdev->has_conns_grp = true;
 53	return ret;
 54}
 55
 56void coresight_remove_conns_sysfs_group(struct coresight_device *csdev)
 57{
 58	if (!csdev)
 59		return;
 60
 61	if (csdev->has_conns_grp) {
 62		sysfs_remove_group(&csdev->dev.kobj, &coresight_conns_group);
 63		csdev->has_conns_grp = false;
 64	}
 65}
 66
 67int coresight_add_sysfs_link(struct coresight_sysfs_link *info)
 68{
 69	int ret = 0;
 70
 71	if (!info)
 72		return -EINVAL;
 73	if (!info->orig || !info->target ||
 74	    !info->orig_name || !info->target_name)
 75		return -EINVAL;
 76	if (!info->orig->has_conns_grp || !info->target->has_conns_grp)
 77		return -EINVAL;
 78
 79	/* first link orig->target */
 80	ret = sysfs_add_link_to_group(&info->orig->dev.kobj,
 81				      coresight_conns_group.name,
 82				      &info->target->dev.kobj,
 83				      info->orig_name);
 84	if (ret)
 85		return ret;
 86
 87	/* second link target->orig */
 88	ret = sysfs_add_link_to_group(&info->target->dev.kobj,
 89				      coresight_conns_group.name,
 90				      &info->orig->dev.kobj,
 91				      info->target_name);
 92
 93	/* error in second link - remove first - otherwise inc counts */
 94	if (ret) {
 95		sysfs_remove_link_from_group(&info->orig->dev.kobj,
 96					     coresight_conns_group.name,
 97					     info->orig_name);
 98	} else {
 99		info->orig->nr_links++;
100		info->target->nr_links++;
101	}
102
103	return ret;
104}
105
106void coresight_remove_sysfs_link(struct coresight_sysfs_link *info)
107{
108	if (!info)
109		return;
110	if (!info->orig || !info->target ||
111	    !info->orig_name || !info->target_name)
112		return;
113
114	sysfs_remove_link_from_group(&info->orig->dev.kobj,
115				     coresight_conns_group.name,
116				     info->orig_name);
117
118	sysfs_remove_link_from_group(&info->target->dev.kobj,
119				     coresight_conns_group.name,
120				     info->target_name);
121
122	info->orig->nr_links--;
123	info->target->nr_links--;
124}
125
126/*
127 * coresight_make_links: Make a link for a connection from a @orig
128 * device to @target, represented by @conn.
129 *
130 *   e.g, for devOrig[output_X] -> devTarget[input_Y] is represented
131 *   as two symbolic links :
132 *
133 *	/sys/.../devOrig/out:X	-> /sys/.../devTarget/
134 *	/sys/.../devTarget/in:Y	-> /sys/.../devOrig/
135 *
136 * The link names are allocated for a device where it appears. i.e, the
137 * "out" link on the master and "in" link on the slave device.
138 * The link info is stored in the connection record for avoiding
139 * the reconstruction of names for removal.
140 */
141int coresight_make_links(struct coresight_device *orig,
142			 struct coresight_connection *conn,
143			 struct coresight_device *target)
144{
145	int ret = -ENOMEM;
146	char *outs = NULL, *ins = NULL;
147	struct coresight_sysfs_link *link = NULL;
148
149	do {
150		outs = devm_kasprintf(&orig->dev, GFP_KERNEL,
151				      "out:%d", conn->outport);
152		if (!outs)
153			break;
154		ins = devm_kasprintf(&target->dev, GFP_KERNEL,
155				     "in:%d", conn->child_port);
156		if (!ins)
157			break;
158		link = devm_kzalloc(&orig->dev,
159				    sizeof(struct coresight_sysfs_link),
160				    GFP_KERNEL);
161		if (!link)
162			break;
163
164		link->orig = orig;
165		link->target = target;
166		link->orig_name = outs;
167		link->target_name = ins;
168
169		ret = coresight_add_sysfs_link(link);
170		if (ret)
171			break;
172
173		conn->link = link;
174
175		/*
176		 * Install the device connection. This also indicates that
177		 * the links are operational on both ends.
178		 */
179		conn->child_dev = target;
180		return 0;
181	} while (0);
182
183	return ret;
184}
185
186/*
187 * coresight_remove_links: Remove the sysfs links for a given connection @conn,
188 * from @orig device to @target device. See coresight_make_links() for more
189 * details.
190 */
191void coresight_remove_links(struct coresight_device *orig,
192			    struct coresight_connection *conn)
193{
194	if (!orig || !conn->link)
195		return;
196
197	coresight_remove_sysfs_link(conn->link);
198
199	devm_kfree(&conn->child_dev->dev, conn->link->target_name);
200	devm_kfree(&orig->dev, conn->link->orig_name);
201	devm_kfree(&orig->dev, conn->link);
202	conn->link = NULL;
203	conn->child_dev = NULL;
204}