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 */
nr_links_show(struct device * dev,struct device_attribute * attr,char * buf)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 */
coresight_create_conns_sysfs_group(struct coresight_device * csdev)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
coresight_remove_conns_sysfs_group(struct coresight_device * csdev)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
coresight_add_sysfs_link(struct coresight_sysfs_link * info)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
coresight_remove_sysfs_link(struct coresight_sysfs_link * info)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 */
coresight_make_links(struct coresight_device * orig,struct coresight_connection * conn,struct coresight_device * target)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 */
coresight_remove_links(struct coresight_device * orig,struct coresight_connection * conn)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