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   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  * Process a node, adding entries for its children and its properties.
  53  */
  54 void proc_device_tree_add_node(struct device_node *np,
  55                                struct proc_dir_entry *de)
  56 {
  57         struct property *pp;
  58         struct proc_dir_entry *ent;
  59         struct device_node *child;
  60         struct proc_dir_entry *list = NULL, **lastp;
  61         const char *p;
  62
  63         set_node_proc_entry(np, de);
  64         lastp = &list;
  65         for (child = NULL; (child = of_get_next_child(np, child));) {
  66                 p = strrchr(child->full_name, '/');
  67                 if (!p)
  68                         p = child->full_name;
  69                 else
  70                         ++p;
  71                 ent = proc_mkdir(p, de);
  72                 if (ent == 0)
  73                         break;
  74                 *lastp = ent;
  75                 ent->next = NULL;
  76                 lastp = &ent->next;
  77                 proc_device_tree_add_node(child, ent);
  78         }
  79         of_node_put(child);
  80         for (pp = np->properties; pp != 0; pp = pp->next) {
  81                 /*
  82                  * Yet another Apple device-tree bogosity: on some machines,
  83                  * they have properties & nodes with the same name. Those
  84                  * properties are quite unimportant for us though, thus we
  85                  * simply "skip" them here, but we do have to check.
  86                  */
  87                 for (ent = list; ent != NULL; ent = ent->next)
  88                         if (!strcmp(ent->name, pp->name))
  89                                 break;
  90                 if (ent != NULL) {
  91                         printk(KERN_WARNING "device-tree: property \"%s\" name"
  92                                " conflicts with node in %s\n", pp->name,
  93                                np->full_name);
  94                         continue;
  95                 }
  96
  97                 /*
  98                  * Unfortunately proc_register puts each new entry
  99                  * at the beginning of the list.  So we rearrange them.
 100                  */
 101                 ent = create_proc_read_entry(pp->name,
 102                                              strncmp(pp->name, "security-", 9)
 103                                              ? S_IRUGO : S_IRUSR, de,
 104                                              property_read_proc, pp);
 105                 if (ent == 0)
 106                         break;
 107                 if (!strncmp(pp->name, "security-", 9))
 108                      ent->size = 0; /* don't leak number of password chars */
 109                 else
 110                      ent->size = pp->length;
 111                 ent->next = NULL;
 112                 *lastp = ent;
 113                 lastp = &ent->next;
 114         }
 115         de->subdir = list;
 116 }
 117
 118 /*
 119  * Called on initialization to set up the /proc/device-tree subtree
 120  */
 121 void proc_device_tree_init(void)
 122 {
 123         struct device_node *root;
 124         if ( !have_of )
 125                 return;
 126         proc_device_tree = proc_mkdir("device-tree", NULL);
 127         if (proc_device_tree == 0)
 128                 return;
 129         root = of_find_node_by_path("/");
 130         if (root == 0) {
 131                 printk(KERN_ERR "/proc/device-tree: can't find root\n");
 132                 return;
 133         }
 134         proc_device_tree_add_node(root, proc_device_tree);
 135         of_node_put(root);
 136 }