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); 123