drivers/of/dynamic.c

   1 /*
   2  * Support for dynamic device trees.
   3  *
   4  * On some platforms, the device tree can be manipulated at runtime.
   5  * The routines in this section support adding, removing and changing
   6  * device tree nodes.
   7  */
   8
   9 #include <linux/of.h>
  10 #include <linux/spinlock.h>
  11 #include <linux/slab.h>
  12 #include <linux/string.h>
  13 #include <linux/proc_fs.h>
  14
  15 #include "of_private.h"
  16
  17 /**
  18  * of_node_get() - Increment refcount of a node
  19  * @node:       Node to inc refcount, NULL is supported to simplify writing of
  20  *              callers
  21  *
  22  * Returns node.
  23  */
  24 struct device_node *of_node_get(struct device_node *node)
  25 {
  26         if (node)
  27                 kobject_get(&node->kobj);
  28         return node;
  29 }
  30 EXPORT_SYMBOL(of_node_get);
  31
  32 /**
  33  * of_node_put() - Decrement refcount of a node
  34  * @node:       Node to dec refcount, NULL is supported to simplify writing of
  35  *              callers
  36  */
  37 void of_node_put(struct device_node *node)
  38 {
  39         if (node)
  40                 kobject_put(&node->kobj);
  41 }
  42 EXPORT_SYMBOL(of_node_put);
  43
  44 static void of_node_remove(struct device_node *np)
  45 {
  46         struct property *pp;
  47
  48         BUG_ON(!of_node_is_initialized(np));
  49
  50         /* only remove properties if on sysfs */
  51         if (of_node_is_attached(np)) {
  52                 for_each_property_of_node(np, pp)
  53                         sysfs_remove_bin_file(&np->kobj, &pp->attr);
  54                 kobject_del(&np->kobj);
  55         }
  56
  57         /* finally remove the kobj_init ref */
  58         of_node_put(np);
  59 }
  60
  61 static BLOCKING_NOTIFIER_HEAD(of_reconfig_chain);
  62
  63 int of_reconfig_notifier_register(struct notifier_block *nb)
  64 {
  65         return blocking_notifier_chain_register(&of_reconfig_chain, nb);
  66 }
  67 EXPORT_SYMBOL_GPL(of_reconfig_notifier_register);
  68
  69 int of_reconfig_notifier_unregister(struct notifier_block *nb)
  70 {
  71         return blocking_notifier_chain_unregister(&of_reconfig_chain, nb);
  72 }
  73 EXPORT_SYMBOL_GPL(of_reconfig_notifier_unregister);
  74
  75 int of_reconfig_notify(unsigned long action, void *p)
  76 {
  77         int rc;
  78
  79         rc = blocking_notifier_call_chain(&of_reconfig_chain, action, p);
  80         return notifier_to_errno(rc);
  81 }
  82
  83 int of_property_notify(int action, struct device_node *np,
  84                        struct property *prop)
  85 {
  86         struct of_prop_reconfig pr;
  87
  88         /* only call notifiers if the node is attached */
  89         if (!of_node_is_attached(np))
  90                 return 0;
  91
  92         pr.dn = np;
  93         pr.prop = prop;
  94         return of_reconfig_notify(action, &pr);
  95 }
  96
  97 /**
  98  * of_attach_node() - Plug a device node into the tree and global list.
  99  */
 100 int of_attach_node(struct device_node *np)
 101 {
 102         unsigned long flags;
 103         int rc;
 104
 105         rc = of_reconfig_notify(OF_RECONFIG_ATTACH_NODE, np);
 106         if (rc)
 107                 return rc;
 108
 109         raw_spin_lock_irqsave(&devtree_lock, flags);
 110         np->sibling = np->parent->child;
 111         np->allnext = np->parent->allnext;
 112         np->parent->allnext = np;
 113         np->parent->child = np;
 114         of_node_clear_flag(np, OF_DETACHED);
 115         raw_spin_unlock_irqrestore(&devtree_lock, flags);
 116
 117         of_node_add(np);
 118         return 0;
 119 }
 120
 121 /**
 122  * of_detach_node() - "Unplug" a node from the device tree.
 123  *
 124  * The caller must hold a reference to the node.  The memory associated with
 125  * the node is not freed until its refcount goes to zero.
 126  */
 127 int of_detach_node(struct device_node *np)
 128 {
 129         struct device_node *parent;
 130         unsigned long flags;
 131         int rc = 0;
 132
 133         rc = of_reconfig_notify(OF_RECONFIG_DETACH_NODE, np);
 134         if (rc)
 135                 return rc;
 136
 137         raw_spin_lock_irqsave(&devtree_lock, flags);
 138
 139         if (of_node_check_flag(np, OF_DETACHED)) {
 140                 /* someone already detached it */
 141                 raw_spin_unlock_irqrestore(&devtree_lock, flags);
 142                 return rc;
 143         }
 144
 145         parent = np->parent;
 146         if (!parent) {
 147                 raw_spin_unlock_irqrestore(&devtree_lock, flags);
 148                 return rc;
 149         }
 150
 151         if (of_allnodes == np)
 152                 of_allnodes = np->allnext;
 153         else {
 154                 struct device_node *prev;
 155                 for (prev = of_allnodes;
 156                      prev->allnext != np;
 157                      prev = prev->allnext)
 158                         ;
 159                 prev->allnext = np->allnext;
 160         }
 161
 162         if (parent->child == np)
 163                 parent->child = np->sibling;
 164         else {
 165                 struct device_node *prevsib;
 166                 for (prevsib = np->parent->child;
 167                      prevsib->sibling != np;
 168                      prevsib = prevsib->sibling)
 169                         ;
 170                 prevsib->sibling = np->sibling;
 171         }
 172
 173         of_node_set_flag(np, OF_DETACHED);
 174         raw_spin_unlock_irqrestore(&devtree_lock, flags);
 175
 176         of_node_remove(np);
 177         return rc;
 178 }
 179
 180 /**
 181  * of_node_release() - release a dynamically allocated node
 182  * @kref: kref element of the node to be released
 183  *
 184  * In of_node_put() this function is passed to kref_put() as the destructor.
 185  */
 186 void of_node_release(struct kobject *kobj)
 187 {
 188         struct device_node *node = kobj_to_device_node(kobj);
 189         struct property *prop = node->properties;
 190
 191         /* We should never be releasing nodes that haven't been detached. */
 192         if (!of_node_check_flag(node, OF_DETACHED)) {
 193                 pr_err("ERROR: Bad of_node_put() on %s\n", node->full_name);
 194                 dump_stack();
 195                 return;
 196         }
 197
 198         if (!of_node_check_flag(node, OF_DYNAMIC))
 199                 return;
 200
 201         while (prop) {
 202                 struct property *next = prop->next;
 203                 kfree(prop->name);
 204                 kfree(prop->value);
 205                 kfree(prop);
 206                 prop = next;
 207
 208                 if (!prop) {
 209                         prop = node->deadprops;
 210                         node->deadprops = NULL;
 211                 }
 212         }
 213         kfree(node->full_name);
 214         kfree(node->data);
 215         kfree(node);
 216 }