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/seq_file.h>
  11 #include <linux/stat.h>
  12 #include <linux/string.h>
  13 #include <linux/of.h>
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <asm/prom.h>
  17 #include <asm/uaccess.h>
  18 #include "internal.h"
  19
  20 static inline void set_node_proc_entry(struct device_node *np,
  21                                        struct proc_dir_entry *de)
  22 {
  23 #ifdef HAVE_ARCH_DEVTREE_FIXUPS
  24         np->pde = de;
  25 #endif
  26 }
  27
  28 static struct proc_dir_entry *proc_device_tree;
  29
  30 /*
  31  * Supply data on a read from /proc/device-tree/node/property.
  32  */
  33 static int property_proc_show(struct seq_file *m, void *v)
  34 {
  35         struct property *pp = m->private;
  36
  37         seq_write(m, pp->value, pp->length);
  38         return 0;
  39 }
  40
  41 static int property_proc_open(struct inode *inode, struct file *file)
  42 {
  43         return single_open(file, property_proc_show, PDE(inode)->data);
  44 }
  45
  46 static const struct file_operations property_proc_fops = {
  47         .owner          = THIS_MODULE,
  48         .open           = property_proc_open,
  49         .read           = seq_read,
  50         .llseek         = seq_lseek,
  51         .release        = single_release,
  52 };
  53
  54 /*
  55  * For a node with a name like "gc@10", we make symlinks called "gc"
  56  * and "@10" to it.
  57  */
  58
  59 /*
  60  * Add a property to a node
  61  */
  62 static struct proc_dir_entry *
  63 __proc_device_tree_add_prop(struct proc_dir_entry *de, struct property *pp,
  64                 const char *name)
  65 {
  66         struct proc_dir_entry *ent;
  67
  68         /*
  69          * Unfortunately proc_register puts each new entry
  70          * at the beginning of the list.  So we rearrange them.
  71          */
  72         ent = proc_create_data(name,
  73                                strncmp(name, "security-", 9) ? S_IRUGO : S_IRUSR,
  74                                de, &property_proc_fops, pp);
  75         if (ent == NULL)
  76                 return NULL;
  77
  78         if (!strncmp(name, "security-", 9))
  79                 ent->size = 0; /* don't leak number of password chars */
  80         else
  81                 ent->size = pp->length;
  82
  83         return ent;
  84 }
  85
  86
  87 void proc_device_tree_add_prop(struct proc_dir_entry *pde, struct property *prop)
  88 {
  89         __proc_device_tree_add_prop(pde, prop, prop->name);
  90 }
  91
  92 void proc_device_tree_remove_prop(struct proc_dir_entry *pde,
  93                                   struct property *prop)
  94 {
  95         remove_proc_entry(prop->name, pde);
  96 }
  97
  98 void proc_device_tree_update_prop(struct proc_dir_entry *pde,
  99                                   struct property *newprop,
 100                                   struct property *oldprop)
 101 {
 102         struct proc_dir_entry *ent;
 103
 104         if (!oldprop) {
 105                 proc_device_tree_add_prop(pde, newprop);
 106                 return;
 107         }
 108
 109         for (ent = pde->subdir; ent != NULL; ent = ent->next)
 110                 if (ent->data == oldprop)
 111                         break;
 112         if (ent == NULL) {
 113                 printk(KERN_WARNING "device-tree: property \"%s\" "
 114                        " does not exist\n", oldprop->name);
 115         } else {
 116                 ent->data = newprop;
 117                 ent->size = newprop->length;
 118         }
 119 }
 120
 121 /*
 122  * Various dodgy firmware might give us nodes and/or properties with
 123  * conflicting names. That's generally ok, except for exporting via /proc,
 124  * so munge names here to ensure they're unique.
 125  */
 126
 127 static int duplicate_name(struct proc_dir_entry *de, const char *name)
 128 {
 129         struct proc_dir_entry *ent;
 130         int found = 0;
 131
 132         spin_lock(&proc_subdir_lock);
 133
 134         for (ent = de->subdir; ent != NULL; ent = ent->next) {
 135                 if (strcmp(ent->name, name) == 0) {
 136                         found = 1;
 137                         break;
 138                 }
 139         }
 140
 141         spin_unlock(&proc_subdir_lock);
 142
 143         return found;
 144 }
 145
 146 static const char *fixup_name(struct device_node *np, struct proc_dir_entry *de,
 147                 const char *name)
 148 {
 149         char *fixed_name;
 150         int fixup_len = strlen(name) + 2 + 1; /* name + #x + \0 */
 151         int i = 1, size;
 152
 153 realloc:
 154         fixed_name = kmalloc(fixup_len, GFP_KERNEL);
 155         if (fixed_name == NULL) {
 156                 printk(KERN_ERR "device-tree: Out of memory trying to fixup "
 157                                 "name \"%s\"\n", name);
 158                 return name;
 159         }
 160
 161 retry:
 162         size = snprintf(fixed_name, fixup_len, "%s#%d", name, i);
 163         size++; /* account for NULL */
 164
 165         if (size > fixup_len) {
 166                 /* We ran out of space, free and reallocate. */
 167                 kfree(fixed_name);
 168                 fixup_len = size;
 169                 goto realloc;
 170         }
 171
 172         if (duplicate_name(de, fixed_name)) {
 173                 /* Multiple duplicates. Retry with a different offset. */
 174                 i++;
 175                 goto retry;
 176         }
 177
 178         printk(KERN_WARNING "device-tree: Duplicate name in %s, "
 179                         "renamed to \"%s\"\n", np->full_name, fixed_name);
 180
 181         return fixed_name;
 182 }
 183
 184 /*
 185  * Process a node, adding entries for its children and its properties.
 186  */
 187 void proc_device_tree_add_node(struct device_node *np,
 188                                struct proc_dir_entry *de)
 189 {
 190         struct property *pp;
 191         struct proc_dir_entry *ent;
 192         struct device_node *child;
 193         const char *p;
 194
 195         set_node_proc_entry(np, de);
 196         for (child = NULL; (child = of_get_next_child(np, child));) {
 197                 /* Use everything after the last slash, or the full name */
 198                 p = kbasename(child->full_name);
 199
 200                 if (duplicate_name(de, p))
 201                         p = fixup_name(np, de, p);
 202
 203                 ent = proc_mkdir(p, de);
 204                 if (ent == NULL)
 205                         break;
 206                 proc_device_tree_add_node(child, ent);
 207         }
 208         of_node_put(child);
 209
 210         for (pp = np->properties; pp != NULL; pp = pp->next) {
 211                 p = pp->name;
 212
 213                 if (strchr(p, '/'))
 214                         continue;
 215
 216                 if (duplicate_name(de, p))
 217                         p = fixup_name(np, de, p);
 218
 219                 ent = __proc_device_tree_add_prop(de, pp, p);
 220                 if (ent == NULL)
 221                         break;
 222         }
 223 }
 224
 225 /*
 226  * Called on initialization to set up the /proc/device-tree subtree
 227  */
 228 void __init proc_device_tree_init(void)
 229 {
 230         struct device_node *root;
 231
 232         proc_device_tree = proc_mkdir("device-tree", NULL);
 233         if (proc_device_tree == NULL)
 234                 return;
 235         root = of_find_node_by_path("/");
 236         if (root == NULL) {
 237                 pr_debug("/proc/device-tree: can't find root\n");
 238                 return;
 239         }
 240         proc_device_tree_add_node(root, proc_device_tree);
 241         of_node_put(root);
 242 }