arch/um/drivers/random.c

   1 /* Much of this ripped from hw_random.c */
   2
   3 #include <linux/module.h>
   4 #include <linux/fs.h>
   5 #include <linux/miscdevice.h>
   6 #include <linux/delay.h>
   7 #include <asm/uaccess.h>
   8 #include "os.h"
   9
  10 /*
  11  * core module and version information
  12  */
  13 #define RNG_VERSION "1.0.0"
  14 #define RNG_MODULE_NAME "random"
  15 #define RNG_DRIVER_NAME   RNG_MODULE_NAME " virtual driver " RNG_VERSION
  16 #define PFX RNG_MODULE_NAME ": "
  17
  18 #define RNG_MISCDEV_MINOR               183 /* official */
  19
  20 static int random_fd = -1;
  21
  22 static int rng_dev_open (struct inode *inode, struct file *filp)
  23 {
  24         /* enforce read-only access to this chrdev */
  25         if ((filp->f_mode & FMODE_READ) == 0)
  26                 return -EINVAL;
  27         if (filp->f_mode & FMODE_WRITE)
  28                 return -EINVAL;
  29
  30         return 0;
  31 }
  32
  33 static ssize_t rng_dev_read (struct file *filp, char __user *buf, size_t size,
  34                              loff_t * offp)
  35 {
  36         u32 data;
  37         int n, ret = 0, have_data;
  38
  39         while(size){
  40                 n = os_read_file(random_fd, &data, sizeof(data));
  41                 if(n > 0){
  42                         have_data = n;
  43                         while (have_data && size) {
  44                                 if (put_user((u8)data, buf++)) {
  45                                         ret = ret ? : -EFAULT;
  46                                         break;
  47                                 }
  48                                 size--;
  49                                 ret++;
  50                                 have_data--;
  51                                 data>>=8;
  52                         }
  53                 }
  54                 else if(n == -EAGAIN){
  55                         if (filp->f_flags & O_NONBLOCK)
  56                                 return ret ? : -EAGAIN;
  57
  58                         if(need_resched()){
  59                                 current->state = TASK_INTERRUPTIBLE;
  60                                 schedule_timeout(1);
  61                         }
  62                 }
  63                 else return n;
  64                 if (signal_pending (current))
  65                         return ret ? : -ERESTARTSYS;
  66         }
  67         return ret;
  68 }
  69
  70 static struct file_operations rng_chrdev_ops = {
  71         .owner          = THIS_MODULE,
  72         .open           = rng_dev_open,
  73         .read           = rng_dev_read,
  74 };
  75
  76 static struct miscdevice rng_miscdev = {
  77         RNG_MISCDEV_MINOR,
  78         RNG_MODULE_NAME,
  79         &rng_chrdev_ops,
  80 };
  81
  82 /*
  83  * rng_init - initialize RNG module
  84  */
  85 static int __init rng_init (void)
  86 {
  87         int err;
  88
  89         err = os_open_file("/dev/random", of_read(OPENFLAGS()), 0);
  90         if(err < 0)
  91                 goto out;
  92
  93         random_fd = err;
  94
  95         err = os_set_fd_block(random_fd, 0);
  96         if(err)
  97                 goto err_out_cleanup_hw;
  98
  99         err = misc_register (&rng_miscdev);
 100         if (err) {
 101                 printk (KERN_ERR PFX "misc device register failed\n");
 102                 goto err_out_cleanup_hw;
 103         }
 104
 105  out:
 106         return err;
 107
 108  err_out_cleanup_hw:
 109         random_fd = -1;
 110         goto out;
 111 }
 112
 113 /*
 114  * rng_cleanup - shutdown RNG module
 115  */
 116 static void __exit rng_cleanup (void)
 117 {
 118         misc_deregister (&rng_miscdev);
 119 }
 120
 121 module_init (rng_init);
 122 module_exit (rng_cleanup);