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  */
16 static 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 }
24 static DEVICE_ATTR_RO(nr_links);
25 
26 static struct attribute *coresight_conns_attrs[] = {
27 	&dev_attr_nr_links.attr,
28 	NULL,
29 };
30 
31 static 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  */
41 int 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 
56 void 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 
67 int 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 EXPORT_SYMBOL_GPL(coresight_add_sysfs_link);
106 
107 void coresight_remove_sysfs_link(struct coresight_sysfs_link *info)
108 {
109 	if (!info)
110 		return;
111 	if (!info->orig || !info->target ||
112 	    !info->orig_name || !info->target_name)
113 		return;
114 
115 	sysfs_remove_link_from_group(&info->orig->dev.kobj,
116 				     coresight_conns_group.name,
117 				     info->orig_name);
118 
119 	sysfs_remove_link_from_group(&info->target->dev.kobj,
120 				     coresight_conns_group.name,
121 				     info->target_name);
122 
123 	info->orig->nr_links--;
124 	info->target->nr_links--;
125 }
126 EXPORT_SYMBOL_GPL(coresight_remove_sysfs_link);
127 
128 /*
129  * coresight_make_links: Make a link for a connection from a @orig
130  * device to @target, represented by @conn.
131  *
132  *   e.g, for devOrig[output_X] -> devTarget[input_Y] is represented
133  *   as two symbolic links :
134  *
135  *	/sys/.../devOrig/out:X	-> /sys/.../devTarget/
136  *	/sys/.../devTarget/in:Y	-> /sys/.../devOrig/
137  *
138  * The link names are allocated for a device where it appears. i.e, the
139  * "out" link on the master and "in" link on the slave device.
140  * The link info is stored in the connection record for avoiding
141  * the reconstruction of names for removal.
142  */
143 int coresight_make_links(struct coresight_device *orig,
144 			 struct coresight_connection *conn,
145 			 struct coresight_device *target)
146 {
147 	int ret = -ENOMEM;
148 	char *outs = NULL, *ins = NULL;
149 	struct coresight_sysfs_link *link = NULL;
150 
151 	do {
152 		outs = devm_kasprintf(&orig->dev, GFP_KERNEL,
153 				      "out:%d", conn->outport);
154 		if (!outs)
155 			break;
156 		ins = devm_kasprintf(&target->dev, GFP_KERNEL,
157 				     "in:%d", conn->child_port);
158 		if (!ins)
159 			break;
160 		link = devm_kzalloc(&orig->dev,
161 				    sizeof(struct coresight_sysfs_link),
162 				    GFP_KERNEL);
163 		if (!link)
164 			break;
165 
166 		link->orig = orig;
167 		link->target = target;
168 		link->orig_name = outs;
169 		link->target_name = ins;
170 
171 		ret = coresight_add_sysfs_link(link);
172 		if (ret)
173 			break;
174 
175 		conn->link = link;
176 
177 		/*
178 		 * Install the device connection. This also indicates that
179 		 * the links are operational on both ends.
180 		 */
181 		conn->child_dev = target;
182 		return 0;
183 	} while (0);
184 
185 	return ret;
186 }
187 
188 /*
189  * coresight_remove_links: Remove the sysfs links for a given connection @conn,
190  * from @orig device to @target device. See coresight_make_links() for more
191  * details.
192  */
193 void coresight_remove_links(struct coresight_device *orig,
194 			    struct coresight_connection *conn)
195 {
196 	if (!orig || !conn->link)
197 		return;
198 
199 	coresight_remove_sysfs_link(conn->link);
200 
201 	devm_kfree(&conn->child_dev->dev, conn->link->target_name);
202 	devm_kfree(&orig->dev, conn->link->orig_name);
203 	devm_kfree(&orig->dev, conn->link);
204 	conn->link = NULL;
205 	conn->child_dev = NULL;
206 }
207