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