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