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/sched.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 static struct proc_dir_entry *proc_device_tree;
  15
  16 /*
  17  * Supply data on a read from /proc/device-tree/node/property.
  18  */
  19 static int property_read_proc(char *page, char **start, off_t off,
  20                               int count, int *eof, void *data)
  21 {
  22         struct property *pp = data;
  23         int n;
  24
  25         if (off >= pp->length) {
  26                 *eof = 1;
  27                 return 0;
  28         }
  29         n = pp->length - off;
  30         if (n > count)
  31                 n = count;
  32         else
  33                 *eof = 1;
  34         memcpy(page, pp->value + off, n);
  35         *start = page;
  36         return n;
  37 }
  38
  39 /*
  40  * For a node with a name like "gc@10", we make symlinks called "gc"
  41  * and "@10" to it.
  42  */
  43
  44 static int devtree_readlink(struct dentry *, char *, int);
  45 static struct dentry *devtree_follow_link(struct dentry *, struct dentry *, unsigned int);
  46
  47 struct inode_operations devtree_symlink_inode_operations = {
  48         NULL,                   /* no file-operations */
  49         NULL,                   /* create */
  50         NULL,                   /* lookup */
  51         NULL,                   /* link */
  52         NULL,                   /* unlink */
  53         NULL,                   /* symlink */
  54         NULL,                   /* mkdir */
  55         NULL,                   /* rmdir */
  56         NULL,                   /* mknod */
  57         NULL,                   /* rename */
  58         devtree_readlink,       /* readlink */
  59         devtree_follow_link,    /* follow_link */
  60         NULL,                   /* readpage */
  61         NULL,                   /* writepage */
  62         NULL,                   /* bmap */
  63         NULL,                   /* truncate */
  64         NULL,                   /* permission */
  65         NULL                    /* smap */
  66 };
  67
  68 static struct dentry *devtree_follow_link(struct dentry *dentry,
  69                                           struct dentry *base,
  70                                           unsigned int follow)
  71 {
  72         struct inode *inode = dentry->d_inode;
  73         struct proc_dir_entry * de;
  74         char *link;
  75
  76         de = (struct proc_dir_entry *) inode->u.generic_ip;
  77         link = (char *) de->data;
  78         return lookup_dentry(link, base, follow);
  79 }
  80
  81 static int devtree_readlink(struct dentry *dentry, char *buffer, int buflen)
  82 {
  83         struct inode *inode = dentry->d_inode;
  84         struct proc_dir_entry * de;
  85         char *link;
  86         int linklen;
  87
  88         de = (struct proc_dir_entry *) inode->u.generic_ip;
  89         link = (char *) de->data;
  90         linklen = strlen(link);
  91         if (linklen > buflen)
  92                 linklen = buflen;
  93         if (copy_to_user(buffer, link, linklen))
  94                 return -EFAULT;
  95         return linklen;
  96 }
  97
  98 /*
  99  * Process a node, adding entries for its children and its properties.
 100  */
 101 static void add_node(struct device_node *np, struct proc_dir_entry *de)
 102 {
 103         struct property *pp;
 104         struct proc_dir_entry *ent;
 105         struct device_node *child, *sib;
 106         const char *p, *at;
 107         int l;
 108         struct proc_dir_entry *list, **lastp, *al;
 109
 110         lastp = &list;
 111         for (pp = np->properties; pp != 0; pp = pp->next) {
 112                 /*
 113                  * Unfortunately proc_register puts each new entry
 114                  * at the beginning of the list.  So we rearrange them.
 115                  */
 116                 ent = kmalloc(sizeof(struct proc_dir_entry), GFP_KERNEL);
 117                 if (ent == 0)
 118                         break;
 119                 memset(ent, 0, sizeof(struct proc_dir_entry));
 120                 ent->name = pp->name;
 121                 ent->namelen = strlen(pp->name);
 122                 ent->mode = S_IFREG | S_IRUGO;
 123                 ent->nlink = 1;
 124                 ent->data = pp;
 125                 ent->read_proc = property_read_proc;
 126                 ent->size = pp->length;
 127                 proc_register(de, ent);
 128                 *lastp = ent;
 129                 lastp = &ent->next;
 130         }
 131         for (child = np->child; child != 0; child = child->sibling) {
 132                 p = strrchr(child->full_name, '/');
 133                 if (p == 0)
 134                         p = child->full_name;
 135                 else
 136                         ++p;
 137                 /* chop off '@0' if the name ends with that */
 138                 l = strlen(p);
 139                 if (l > 2 && p[l-2] == '@' && p[l-1] == '0')
 140                         l -= 2;
 141                 ent = kmalloc(sizeof(struct proc_dir_entry), GFP_KERNEL);
 142                 if (ent == 0)
 143                         break;
 144                 memset(ent, 0, sizeof(struct proc_dir_entry));
 145                 ent->name = p;
 146                 ent->namelen = l;
 147                 ent->mode = S_IFDIR | S_IRUGO | S_IXUGO;
 148                 ent->nlink = 2;
 149                 proc_register(de, ent);
 150                 *lastp = ent;
 151                 lastp = &ent->next;
 152                 add_node(child, ent);
 153
 154                 /*
 155                  * If we left the address part on the name, consider
 156                  * adding symlinks from the name and address parts.
 157                  */
 158                 if (p[l] != 0 || (at = strchr(p, '@')) == 0)
 159                         continue;
 160
 161                 /*
 162                  * If this is the first node with a given name property,
 163                  * add a symlink with the name property as its name.
 164                  */
 165                 for (sib = np->child; sib != child; sib = sib->sibling)
 166                         if (strcmp(sib->name, child->name) == 0)
 167                                 break;
 168                 if (sib == child && strncmp(p, child->name, l) != 0) {
 169                         al = kmalloc(sizeof(struct proc_dir_entry),
 170                                      GFP_KERNEL);
 171                         if (al == 0)
 172                                 break;
 173                         memset(al, 0, sizeof(struct proc_dir_entry));
 174                         al->name = child->name;
 175                         al->namelen = strlen(child->name);
 176                         al->mode = S_IFLNK | S_IRUGO | S_IXUGO;
 177                         al->nlink = 1;
 178                         al->data = (void *) ent->name;
 179                         al->ops = &devtree_symlink_inode_operations;
 180                         proc_register(de, al);
 181                         *lastp = al;
 182                         lastp = &al->next;
 183                 }
 184
 185                 /*
 186                  * Add another directory with the @address part as its name.
 187                  */
 188                 al = kmalloc(sizeof(struct proc_dir_entry), GFP_KERNEL);
 189                 if (al == 0)
 190                         break;
 191                 memset(al, 0, sizeof(struct proc_dir_entry));
 192                 al->name = at;
 193                 al->namelen = strlen(at);
 194                 al->mode = S_IFLNK | S_IRUGO | S_IXUGO;
 195                 al->nlink = 1;
 196                 al->data = (void *) ent->name;
 197                 al->ops = &devtree_symlink_inode_operations;
 198                 proc_register(de, al);
 199                 *lastp = al;
 200                 lastp = &al->next;
 201         }
 202         *lastp = 0;
 203         de->subdir = list;
 204 }
 205
 206 /*
 207  * Called on initialization to set up the /proc/device-tree subtree
 208  */
 209 void proc_device_tree_init(void)
 210 {
 211         struct device_node *root;
 212         if ( !have_of )
 213                 return;
 214         proc_device_tree = create_proc_entry("device-tree", S_IFDIR, 0);
 215         if (proc_device_tree == 0)
 216                 return;
 217         root = find_path_device("/");
 218         if (root == 0) {
 219                 printk(KERN_ERR "/proc/device-tree: can't find root\n");
 220                 return;
 221         }
 222         add_node(root, proc_device_tree);
 223 }