drivers/hwtracing/coresight/coresight-sysfs.c

   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
 106 void 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  */
 141 int 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  */
 191 void 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 }