Merge /spare/repo/linux-2.6/
[linux-2.6] / arch / um / drivers / random.c
1 /* Copyright (C) 2005 Jeff Dike <jdike@addtoit.com> */
2 /* Much of this ripped from drivers/char/hw_random.c, see there for other
3  * copyright.
4  *
5  * This software may be used and distributed according to the terms
6  * of the GNU General Public License, incorporated herein by reference.
7  */
8 #include <linux/module.h>
9 #include <linux/fs.h>
10 #include <linux/miscdevice.h>
11 #include <linux/delay.h>
12 #include <asm/uaccess.h>
13 #include "os.h"
14
15 /*
16  * core module and version information
17  */
18 #define RNG_VERSION "1.0.0"
19 #define RNG_MODULE_NAME "random"
20
21 #define RNG_MISCDEV_MINOR               183 /* official */
22
23 static int random_fd = -1;
24
25 static int rng_dev_open (struct inode *inode, struct file *filp)
26 {
27         /* enforce read-only access to this chrdev */
28         if ((filp->f_mode & FMODE_READ) == 0)
29                 return -EINVAL;
30         if (filp->f_mode & FMODE_WRITE)
31                 return -EINVAL;
32
33         return 0;
34 }
35
36 static ssize_t rng_dev_read (struct file *filp, char __user *buf, size_t size,
37                              loff_t * offp)
38 {
39         u32 data;
40         int n, ret = 0, have_data;
41
42         while(size){
43                 n = os_read_file(random_fd, &data, sizeof(data));
44                 if(n > 0){
45                         have_data = n;
46                         while (have_data && size) {
47                                 if (put_user((u8)data, buf++)) {
48                                         ret = ret ? : -EFAULT;
49                                         break;
50                                 }
51                                 size--;
52                                 ret++;
53                                 have_data--;
54                                 data>>=8;
55                         }
56                 }
57                 else if(n == -EAGAIN){
58                         if (filp->f_flags & O_NONBLOCK)
59                                 return ret ? : -EAGAIN;
60
61                         if(need_resched()){
62                                 current->state = TASK_INTERRUPTIBLE;
63                                 schedule_timeout(1);
64                         }
65                 }
66                 else return n;
67                 if (signal_pending (current))
68                         return ret ? : -ERESTARTSYS;
69         }
70         return ret;
71 }
72
73 static struct file_operations rng_chrdev_ops = {
74         .owner          = THIS_MODULE,
75         .open           = rng_dev_open,
76         .read           = rng_dev_read,
77 };
78
79 static struct miscdevice rng_miscdev = {
80         RNG_MISCDEV_MINOR,
81         RNG_MODULE_NAME,
82         &rng_chrdev_ops,
83 };
84
85 /*
86  * rng_init - initialize RNG module
87  */
88 static int __init rng_init (void)
89 {
90         int err;
91
92         err = os_open_file("/dev/random", of_read(OPENFLAGS()), 0);
93         if(err < 0)
94                 goto out;
95
96         random_fd = err;
97
98         err = os_set_fd_block(random_fd, 0);
99         if(err)
100                 goto err_out_cleanup_hw;
101
102         err = misc_register (&rng_miscdev);
103         if (err) {
104                 printk (KERN_ERR RNG_MODULE_NAME ": misc device register failed\n");
105                 goto err_out_cleanup_hw;
106         }
107
108  out:
109         return err;
110
111  err_out_cleanup_hw:
112         random_fd = -1;
113         goto out;
114 }
115
116 /*
117  * rng_cleanup - shutdown RNG module
118  */
119 static void __exit rng_cleanup (void)
120 {
121         misc_deregister (&rng_miscdev);
122 }
123
124 module_init (rng_init);
125 module_exit (rng_cleanup);
126
127 MODULE_DESCRIPTION("UML Host Random Number Generator (RNG) driver");
128 MODULE_LICENSE("GPL");