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/printk.h>
  12 #include <linux/stat.h>
  13 #include <linux/string.h>
  14 #include <linux/of.h>
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17 #include <asm/prom.h>
  18 #include <asm/uaccess.h>
  19 #include "internal.h"
  20
  21 static inline void set_node_proc_entry(struct device_node *np,
  22                                        struct proc_dir_entry *de)
  23 {
  24 #ifdef HAVE_ARCH_DEVTREE_FIXUPS
  25         np->pde = de;
  26 #endif
  27 }
  28
  29 static struct proc_dir_entry *proc_device_tree;
  30
  31 /*
  32  * Supply data on a read from /proc/device-tree/node/property.
  33  */
  34 static int property_proc_show(struct seq_file *m, void *v)
  35 {
  36         struct property *pp = m->private;
  37
  38         seq_write(m, pp->value, pp->length);
  39         return 0;
  40 }
  41
  42 static int property_proc_open(struct inode *inode, struct file *file)
  43 {
  44         return single_open(file, property_proc_show, PDE_DATA(inode));
  45 }
  46
  47 static const struct file_operations property_proc_fops = {
  48         .owner          = THIS_MODULE,
  49         .open           = property_proc_open,
  50         .read           = seq_read,
  51         .llseek         = seq_lseek,
  52         .release        = single_release,
  53 };
  54
  55 /*
  56  * For a node with a name like "gc@10", we make symlinks called "gc"
  57  * and "@10" to it.
  58  */
  59
  60 /*
  61  * Add a property to a node
  62  */
  63 static struct proc_dir_entry *
  64 __proc_device_tree_add_prop(struct proc_dir_entry *de, struct property *pp,
  65                 const char *name)
  66 {
  67         struct proc_dir_entry *ent;
  68
  69         /*
  70          * Unfortunately proc_register puts each new entry
  71          * at the beginning of the list.  So we rearrange them.
  72          */
  73         ent = proc_create_data(name,
  74                                strncmp(name, "security-", 9) ? S_IRUGO : S_IRUSR,
  75                                de, &property_proc_fops, pp);
  76         if (ent == NULL)
  77                 return NULL;
  78
  79         if (!strncmp(name, "security-", 9))
  80                 ent->size = 0; /* don't leak number of password chars */
  81         else
  82                 ent->size = pp->length;
  83
  84         return ent;
  85 }
  86
  87
  88 void proc_device_tree_add_prop(struct proc_dir_entry *pde, struct property *prop)
  89 {
  90         __proc_device_tree_add_prop(pde, prop, prop->name);
  91 }
  92
  93 void proc_device_tree_remove_prop(struct proc_dir_entry *pde,
  94                                   struct property *prop)
  95 {
  96         remove_proc_entry(prop->name, pde);
  97 }
  98
  99 void proc_device_tree_update_prop(struct proc_dir_entry *pde,
 100                                   struct property *newprop,
 101                                   struct property *oldprop)
 102 {
 103         struct proc_dir_entry *ent;
 104
 105         if (!oldprop) {
 106                 proc_device_tree_add_prop(pde, newprop);
 107                 return;
 108         }
 109
 110         for (ent = pde->subdir; ent != NULL; ent = ent->next)
 111                 if (ent->data == oldprop)
 112                         break;
 113         if (ent == NULL) {
 114                 pr_warn("device-tree: property \"%s\" does not exist\n",
 115                         oldprop->name);
 116         } else {
 117                 ent->data = newprop;
 118                 ent->size = newprop->length;
 119         }
 120 }
 121
 122 /*
 123  * Various dodgy firmware might give us nodes and/or properties with
 124  * conflicting names. That's generally ok, except for exporting via /proc,
 125  * so munge names here to ensure they're unique.
 126  */
 127
 128 static int duplicate_name(struct proc_dir_entry *de, const char *name)
 129 {
 130         struct proc_dir_entry *ent;
 131         int found = 0;
 132
 133         spin_lock(&proc_subdir_lock);
 134
 135         for (ent = de->subdir; ent != NULL; ent = ent->next) {
 136                 if (strcmp(ent->name, name) == 0) {
 137                         found = 1;
 138                         break;
 139                 }
 140         }
 141
 142         spin_unlock(&proc_subdir_lock);
 143
 144         return found;
 145 }
 146
 147 static const char *fixup_name(struct device_node *np, struct proc_dir_entry *de,
 148                 const char *name)
 149 {
 150         char *fixed_name;
 151         int fixup_len = strlen(name) + 2 + 1; /* name + #x + \0 */
 152         int i = 1, size;
 153
 154 realloc:
 155         fixed_name = kmalloc(fixup_len, GFP_KERNEL);
 156         if (fixed_name == NULL) {
 157                 pr_err("device-tree: Out of memory trying to fixup "
 158                        "name \"%s\"\n", name);
 159                 return name;
 160         }
 161
 162 retry:
 163         size = snprintf(fixed_name, fixup_len, "%s#%d", name, i);
 164         size++; /* account for NULL */
 165
 166         if (size > fixup_len) {
 167                 /* We ran out of space, free and reallocate. */
 168                 kfree(fixed_name);
 169                 fixup_len = size;
 170                 goto realloc;
 171         }
 172
 173         if (duplicate_name(de, fixed_name)) {
 174                 /* Multiple duplicates. Retry with a different offset. */
 175                 i++;
 176                 goto retry;
 177         }
 178
 179         pr_warn("device-tree: Duplicate name in %s, renamed to \"%s\"\n",
 180                 np->full_name, fixed_name);
 181
 182         return fixed_name;
 183 }
 184
 185 /*
 186  * Process a node, adding entries for its children and its properties.
 187  */
 188 void proc_device_tree_add_node(struct device_node *np,
 189                                struct proc_dir_entry *de)
 190 {
 191         struct property *pp;
 192         struct proc_dir_entry *ent;
 193         struct device_node *child;
 194         const char *p;
 195
 196         set_node_proc_entry(np, de);
 197         for (child = NULL; (child = of_get_next_child(np, child));) {
 198                 /* Use everything after the last slash, or the full name */
 199                 p = kbasename(child->full_name);
 200
 201                 if (duplicate_name(de, p))
 202                         p = fixup_name(np, de, p);
 203
 204                 ent = proc_mkdir(p, de);
 205                 if (ent == NULL)
 206                         break;
 207                 proc_device_tree_add_node(child, ent);
 208         }
 209         of_node_put(child);
 210
 211         for (pp = np->properties; pp != NULL; pp = pp->next) {
 212                 p = pp->name;
 213
 214                 if (strchr(p, '/'))
 215                         continue;
 216
 217                 if (duplicate_name(de, p))
 218                         p = fixup_name(np, de, p);
 219
 220                 ent = __proc_device_tree_add_prop(de, pp, p);
 221                 if (ent == NULL)
 222                         break;
 223         }
 224 }
 225
 226 /*
 227  * Called on initialization to set up the /proc/device-tree subtree
 228  */
 229 void __init proc_device_tree_init(void)
 230 {
 231         struct device_node *root;
 232
 233         proc_device_tree = proc_mkdir("device-tree", NULL);
 234         if (proc_device_tree == NULL)
 235                 return;
 236         root = of_find_node_by_path("/");
 237         if (root == NULL) {
 238                 pr_debug("/proc/device-tree: can't find root\n");
 239                 return;
 240         }
 241         proc_device_tree_add_node(root, proc_device_tree);
 242         of_node_put(root);
 243 }