drivers/of/kobj.c

   1 #include <linux/of.h>
   2 #include <linux/slab.h>
   3
   4 #include "of_private.h"
   5
   6 /* true when node is initialized */
   7 static int of_node_is_initialized(struct device_node *node)
   8 {
   9         return node && node->kobj.state_initialized;
  10 }
  11
  12 /* true when node is attached (i.e. present on sysfs) */
  13 int of_node_is_attached(struct device_node *node)
  14 {
  15         return node && node->kobj.state_in_sysfs;
  16 }
  17
  18
  19 #ifndef CONFIG_OF_DYNAMIC
  20 static void of_node_release(struct kobject *kobj)
  21 {
  22         /* Without CONFIG_OF_DYNAMIC, no nodes gets freed */
  23 }
  24 #endif /* CONFIG_OF_DYNAMIC */
  25
  26 struct kobj_type of_node_ktype = {
  27         .release = of_node_release,
  28 };
  29
  30 static ssize_t of_node_property_read(struct file *filp, struct kobject *kobj,
  31                                 struct bin_attribute *bin_attr, char *buf,
  32                                 loff_t offset, size_t count)
  33 {
  34         struct property *pp = container_of(bin_attr, struct property, attr);
  35         return memory_read_from_buffer(buf, count, &offset, pp->value, pp->length);
  36 }
  37
  38 /* always return newly allocated name, caller must free after use */
  39 static const char *safe_name(struct kobject *kobj, const char *orig_name)
  40 {
  41         const char *name = orig_name;
  42         struct kernfs_node *kn;
  43         int i = 0;
  44
  45         /* don't be a hero. After 16 tries give up */
  46         while (i < 16 && (kn = sysfs_get_dirent(kobj->sd, name))) {
  47                 sysfs_put(kn);
  48                 if (name != orig_name)
  49                         kfree(name);
  50                 name = kasprintf(GFP_KERNEL, "%s#%i", orig_name, ++i);
  51         }
  52
  53         if (name == orig_name) {
  54                 name = kstrdup(orig_name, GFP_KERNEL);
  55         } else {
  56                 pr_warn("Duplicate name in %s, renamed to \"%s\"\n",
  57                         kobject_name(kobj), name);
  58         }
  59         return name;
  60 }
  61
  62 int __of_add_property_sysfs(struct device_node *np, struct property *pp)
  63 {
  64         int rc;
  65
  66         /* Important: Don't leak passwords */
  67         bool secure = strncmp(pp->name, "security-", 9) == 0;
  68
  69         if (!IS_ENABLED(CONFIG_SYSFS))
  70                 return 0;
  71
  72         if (!of_kset || !of_node_is_attached(np))
  73                 return 0;
  74
  75         sysfs_bin_attr_init(&pp->attr);
  76         pp->attr.attr.name = safe_name(&np->kobj, pp->name);
  77         pp->attr.attr.mode = secure ? 0400 : 0444;
  78         pp->attr.size = secure ? 0 : pp->length;
  79         pp->attr.read = of_node_property_read;
  80
  81         rc = sysfs_create_bin_file(&np->kobj, &pp->attr);
  82         WARN(rc, "error adding attribute %s to node %pOF\n", pp->name, np);
  83         return rc;
  84 }
  85
  86 void __of_sysfs_remove_bin_file(struct device_node *np, struct property *prop)
  87 {
  88         if (!IS_ENABLED(CONFIG_SYSFS))
  89                 return;
  90
  91         sysfs_remove_bin_file(&np->kobj, &prop->attr);
  92         kfree(prop->attr.attr.name);
  93 }
  94
  95 void __of_remove_property_sysfs(struct device_node *np, struct property *prop)
  96 {
  97         /* at early boot, bail here and defer setup to of_init() */
  98         if (of_kset && of_node_is_attached(np))
  99                 __of_sysfs_remove_bin_file(np, prop);
 100 }
 101
 102 void __of_update_property_sysfs(struct device_node *np, struct property *newprop,
 103                 struct property *oldprop)
 104 {
 105         /* At early boot, bail out and defer setup to of_init() */
 106         if (!of_kset)
 107                 return;
 108
 109         if (oldprop)
 110                 __of_sysfs_remove_bin_file(np, oldprop);
 111         __of_add_property_sysfs(np, newprop);
 112 }
 113
 114 int __of_attach_node_sysfs(struct device_node *np)
 115 {
 116         const char *name;
 117         struct kobject *parent;
 118         struct property *pp;
 119         int rc;
 120
 121         if (!of_kset)
 122                 return 0;
 123
 124         np->kobj.kset = of_kset;
 125         if (!np->parent) {
 126                 /* Nodes without parents are new top level trees */
 127                 name = safe_name(&of_kset->kobj, "base");
 128                 parent = NULL;
 129         } else {
 130                 name = safe_name(&np->parent->kobj, kbasename(np->full_name));
 131                 parent = &np->parent->kobj;
 132         }
 133         if (!name)
 134                 return -ENOMEM;
 135         rc = kobject_add(&np->kobj, parent, "%s", name);
 136         kfree(name);
 137         if (rc)
 138                 return rc;
 139
 140         for_each_property_of_node(np, pp)
 141                 __of_add_property_sysfs(np, pp);
 142
 143         return 0;
 144 }
 145
 146 void __of_detach_node_sysfs(struct device_node *np)
 147 {
 148         struct property *pp;
 149
 150         BUG_ON(!of_node_is_initialized(np));
 151         if (!of_kset)
 152                 return;
 153
 154         /* only remove properties if on sysfs */
 155         if (of_node_is_attached(np)) {
 156                 for_each_property_of_node(np, pp)
 157                         __of_sysfs_remove_bin_file(np, pp);
 158                 kobject_del(&np->kobj);
 159         }
 160
 161         /* finally remove the kobj_init ref */
 162         of_node_put(np);
 163 }
 164