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