fs/proc/proc_devtree.c

   1 /*
   2  * proc_devtree.c - handles /proc/device-tree
   3  *
   4  * Copyright 1997 Paul Mackerras
   5  */
   6 #include <linux/errno.h>
   7 #include <linux/init.h>
   8 #include <linux/time.h>
   9 #include <linux/proc_fs.h>
  10 #include <linux/stat.h>
  11 #include <linux/string.h>
  12 #include <asm/prom.h>
  13 #include <asm/uaccess.h>
  14
  15 #ifndef HAVE_ARCH_DEVTREE_FIXUPS
  16 static inline void set_node_proc_entry(struct device_node *np,
  17                                        struct proc_dir_entry *de)
  18 {
  19 }
  20 #endif
  21
  22 static struct proc_dir_entry *proc_device_tree;
  23
  24 /*
  25  * Supply data on a read from /proc/device-tree/node/property.
  26  */
  27 static int property_read_proc(char *page, char **start, off_t off,
  28                               int count, int *eof, void *data)
  29 {
  30         struct property *pp = data;
  31         int n;
  32
  33         if (off >= pp->length) {
  34                 *eof = 1;
  35                 return 0;
  36         }
  37         n = pp->length - off;
  38         if (n > count)
  39                 n = count;
  40         else
  41                 *eof = 1;
  42         memcpy(page, (char *)pp->value + off, n);
  43         *start = page;
  44         return n;
  45 }
  46
  47 /*
  48  * For a node with a name like "gc@10", we make symlinks called "gc"
  49  * and "@10" to it.
  50  */
  51
  52 /*
  53  * Add a property to a node
  54  */
  55 static struct proc_dir_entry *
  56 __proc_device_tree_add_prop(struct proc_dir_entry *de, struct property *pp,
  57                 const char *name)
  58 {
  59         struct proc_dir_entry *ent;
  60
  61         /*
  62          * Unfortunately proc_register puts each new entry
  63          * at the beginning of the list.  So we rearrange them.
  64          */
  65         ent = create_proc_read_entry(name,
  66                                      strncmp(name, "security-", 9)
  67                                      ? S_IRUGO : S_IRUSR, de,
  68                                      property_read_proc, pp);
  69         if (ent == NULL)
  70                 return NULL;
  71
  72         if (!strncmp(name, "security-", 9))
  73                 ent->size = 0; /* don't leak number of password chars */
  74         else
  75                 ent->size = pp->length;
  76
  77         return ent;
  78 }
  79
  80
  81 void proc_device_tree_add_prop(struct proc_dir_entry *pde, struct property *prop)
  82 {
  83         __proc_device_tree_add_prop(pde, prop, prop->name);
  84 }
  85
  86 void proc_device_tree_remove_prop(struct proc_dir_entry *pde,
  87                                   struct property *prop)
  88 {
  89         remove_proc_entry(prop->name, pde);
  90 }
  91
  92 void proc_device_tree_update_prop(struct proc_dir_entry *pde,
  93                                   struct property *newprop,
  94                                   struct property *oldprop)
  95 {
  96         struct proc_dir_entry *ent;
  97
  98         for (ent = pde->subdir; ent != NULL; ent = ent->next)
  99                 if (ent->data == oldprop)
 100                         break;
 101         if (ent == NULL) {
 102                 printk(KERN_WARNING "device-tree: property \"%s\" "
 103                        " does not exist\n", oldprop->name);
 104         } else {
 105                 ent->data = newprop;
 106                 ent->size = newprop->length;
 107         }
 108 }
 109
 110 /*
 111  * Various dodgy firmware might give us nodes and/or properties with
 112  * conflicting names. That's generally ok, except for exporting via /proc,
 113  * so munge names here to ensure they're unique.
 114  */
 115
 116 static int duplicate_name(struct proc_dir_entry *de, const char *name)
 117 {
 118         struct proc_dir_entry *ent;
 119         int found = 0;
 120
 121         spin_lock(&proc_subdir_lock);
 122
 123         for (ent = de->subdir; ent != NULL; ent = ent->next) {
 124                 if (strcmp(ent->name, name) == 0) {
 125                         found = 1;
 126                         break;
 127                 }
 128         }
 129
 130         spin_unlock(&proc_subdir_lock);
 131
 132         return found;
 133 }
 134
 135 static const char *fixup_name(struct device_node *np, struct proc_dir_entry *de,
 136                 const char *name)
 137 {
 138         char *fixed_name;
 139         int fixup_len = strlen(name) + 2 + 1; /* name + #x + \0 */
 140         int i = 1, size;
 141
 142 realloc:
 143         fixed_name = kmalloc(fixup_len, GFP_KERNEL);
 144         if (fixed_name == NULL) {
 145                 printk(KERN_ERR "device-tree: Out of memory trying to fixup "
 146                                 "name \"%s\"\n", name);
 147                 return name;
 148         }
 149
 150 retry:
 151         size = snprintf(fixed_name, fixup_len, "%s#%d", name, i);
 152         size++; /* account for NULL */
 153
 154         if (size > fixup_len) {
 155                 /* We ran out of space, free and reallocate. */
 156                 kfree(fixed_name);
 157                 fixup_len = size;
 158                 goto realloc;
 159         }
 160
 161         if (duplicate_name(de, fixed_name)) {
 162                 /* Multiple duplicates. Retry with a different offset. */
 163                 i++;
 164                 goto retry;
 165         }
 166
 167         printk(KERN_WARNING "device-tree: Duplicate name in %s, "
 168                         "renamed to \"%s\"\n", np->full_name, fixed_name);
 169
 170         return fixed_name;
 171 }
 172
 173 /*
 174  * Process a node, adding entries for its children and its properties.
 175  */
 176 void proc_device_tree_add_node(struct device_node *np,
 177                                struct proc_dir_entry *de)
 178 {
 179         struct property *pp;
 180         struct proc_dir_entry *ent;
 181         struct device_node *child;
 182         const char *p;
 183
 184         set_node_proc_entry(np, de);
 185         for (child = NULL; (child = of_get_next_child(np, child));) {
 186                 /* Use everything after the last slash, or the full name */
 187                 p = strrchr(child->full_name, '/');
 188                 if (!p)
 189                         p = child->full_name;
 190                 else
 191                         ++p;
 192
 193                 if (duplicate_name(de, p))
 194                         p = fixup_name(np, de, p);
 195
 196                 ent = proc_mkdir(p, de);
 197                 if (ent == 0)
 198                         break;
 199                 proc_device_tree_add_node(child, ent);
 200         }
 201         of_node_put(child);
 202
 203         for (pp = np->properties; pp != 0; pp = pp->next) {
 204                 p = pp->name;
 205
 206                 if (duplicate_name(de, p))
 207                         p = fixup_name(np, de, p);
 208
 209                 ent = __proc_device_tree_add_prop(de, pp, p);
 210                 if (ent == 0)
 211                         break;
 212         }
 213 }
 214
 215 /*
 216  * Called on initialization to set up the /proc/device-tree subtree
 217  */
 218 void __init proc_device_tree_init(void)
 219 {
 220         struct device_node *root;
 221         if ( !have_of )
 222                 return;
 223         proc_device_tree = proc_mkdir("device-tree", NULL);
 224         if (proc_device_tree == 0)
 225                 return;
 226         root = of_find_node_by_path("/");
 227         if (root == 0) {
 228                 printk(KERN_ERR "/proc/device-tree: can't find root\n");
 229                 return;
 230         }
 231         proc_device_tree_add_node(root, proc_device_tree);
 232         of_node_put(root);
 233 }