fs/proc/devices.c

   1 #include <linux/fs.h>
   2 #include <linux/init.h>
   3 #include <linux/proc_fs.h>
   4 #include <linux/seq_file.h>
   5
   6 static int devinfo_show(struct seq_file *f, void *v)
   7 {
   8         int i = *(loff_t *) v;
   9
  10         if (i < CHRDEV_MAJOR_HASH_SIZE) {
  11                 if (i == 0)
  12                         seq_puts(f, "Character devices:\n");
  13                 chrdev_show(f, i);
  14         }
  15 #ifdef CONFIG_BLOCK
  16         else {
  17                 i -= CHRDEV_MAJOR_HASH_SIZE;
  18                 if (i == 0)
  19                         seq_puts(f, "\nBlock devices:\n");
  20                 blkdev_show(f, i);
  21         }
  22 #endif
  23         return 0;
  24 }
  25
  26 static void *devinfo_start(struct seq_file *f, loff_t *pos)
  27 {
  28         if (*pos < (BLKDEV_MAJOR_HASH_SIZE + CHRDEV_MAJOR_HASH_SIZE))
  29                 return pos;
  30         return NULL;
  31 }
  32
  33 static void *devinfo_next(struct seq_file *f, void *v, loff_t *pos)
  34 {
  35         (*pos)++;
  36         if (*pos >= (BLKDEV_MAJOR_HASH_SIZE + CHRDEV_MAJOR_HASH_SIZE))
  37                 return NULL;
  38         return pos;
  39 }
  40
  41 static void devinfo_stop(struct seq_file *f, void *v)
  42 {
  43         /* Nothing to do */
  44 }
  45
  46 static const struct seq_operations devinfo_ops = {
  47         .start = devinfo_start,
  48         .next  = devinfo_next,
  49         .stop  = devinfo_stop,
  50         .show  = devinfo_show
  51 };
  52
  53 static int devinfo_open(struct inode *inode, struct file *filp)
  54 {
  55         return seq_open(filp, &devinfo_ops);
  56 }
  57
  58 static const struct file_operations proc_devinfo_operations = {
  59         .open           = devinfo_open,
  60         .read           = seq_read,
  61         .llseek         = seq_lseek,
  62         .release        = seq_release,
  63 };
  64
  65 static int __init proc_devices_init(void)
  66 {
  67         proc_create("devices", 0, NULL, &proc_devinfo_operations);
  68         return 0;
  69 }
  70 fs_initcall(proc_devices_init);