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 {
  57         struct proc_dir_entry *ent;
  58
  59         /*
  60          * Unfortunately proc_register puts each new entry
  61          * at the beginning of the list.  So we rearrange them.
  62          */
  63         ent = create_proc_read_entry(pp->name,
  64                                      strncmp(pp->name, "security-", 9)
  65                                      ? S_IRUGO : S_IRUSR, de,
  66                                      property_read_proc, pp);
  67         if (ent == NULL)
  68                 return NULL;
  69
  70         if (!strncmp(pp->name, "security-", 9))
  71                 ent->size = 0; /* don't leak number of password chars */
  72         else
  73                 ent->size = pp->length;
  74
  75         return ent;
  76 }
  77
  78
  79 void proc_device_tree_add_prop(struct proc_dir_entry *pde, struct property *prop)
  80 {
  81         __proc_device_tree_add_prop(pde, prop);
  82 }
  83
  84 /*
  85  * Process a node, adding entries for its children and its properties.
  86  */
  87 void proc_device_tree_add_node(struct device_node *np,
  88                                struct proc_dir_entry *de)
  89 {
  90         struct property *pp;
  91         struct proc_dir_entry *ent;
  92         struct device_node *child;
  93         const char *p;
  94
  95         set_node_proc_entry(np, de);
  96         for (child = NULL; (child = of_get_next_child(np, child));) {
  97                 p = strrchr(child->full_name, '/');
  98                 if (!p)
  99                         p = child->full_name;
 100                 else
 101                         ++p;
 102                 ent = proc_mkdir(p, de);
 103                 if (ent == 0)
 104                         break;
 105                 proc_device_tree_add_node(child, ent);
 106         }
 107         of_node_put(child);
 108         for (pp = np->properties; pp != 0; pp = pp->next) {
 109                 /*
 110                  * Yet another Apple device-tree bogosity: on some machines,
 111                  * they have properties & nodes with the same name. Those
 112                  * properties are quite unimportant for us though, thus we
 113                  * simply "skip" them here, but we do have to check.
 114                  */
 115                 for (ent = de->subdir; ent != NULL; ent = ent->next)
 116                         if (!strcmp(ent->name, pp->name))
 117                                 break;
 118                 if (ent != NULL) {
 119                         printk(KERN_WARNING "device-tree: property \"%s\" name"
 120                                " conflicts with node in %s\n", pp->name,
 121                                np->full_name);
 122                         continue;
 123                 }
 124
 125                 ent = __proc_device_tree_add_prop(de, pp);
 126                 if (ent == 0)
 127                         break;
 128         }
 129 }
 130
 131 /*
 132  * Called on initialization to set up the /proc/device-tree subtree
 133  */
 134 void proc_device_tree_init(void)
 135 {
 136         struct device_node *root;
 137         if ( !have_of )
 138                 return;
 139         proc_device_tree = proc_mkdir("device-tree", NULL);
 140         if (proc_device_tree == 0)
 141                 return;
 142         root = of_find_node_by_path("/");
 143         if (root == 0) {
 144                 printk(KERN_ERR "/proc/device-tree: can't find root\n");
 145                 return;
 146         }
 147         proc_device_tree_add_node(root, proc_device_tree);
 148         of_node_put(root);
 149 }