1 /* Copyright (C) 2005 - 2008 Jeff Dike <jdike@{linux.intel,addtoit}.com> */
3 /* Much of this ripped from drivers/char/hw_random.c, see there for other
6 * This software may be used and distributed according to the terms
7 * of the GNU General Public License, incorporated herein by reference.
9 #include <linux/sched/signal.h>
10 #include <linux/module.h>
12 #include <linux/interrupt.h>
13 #include <linux/miscdevice.h>
14 #include <linux/delay.h>
15 #include <linux/uaccess.h>
20 * core module and version information
22 #define RNG_VERSION "1.0.0"
23 #define RNG_MODULE_NAME "hw_random"
25 #define RNG_MISCDEV_MINOR 183 /* official */
27 /* Changed at init time, in the non-modular case, and at module load
28 * time, in the module case. Presumably, the module subsystem
29 * protects against a module being loaded twice at the same time.
31 static int random_fd
= -1;
32 static DECLARE_WAIT_QUEUE_HEAD(host_read_wait
);
34 static int rng_dev_open (struct inode
*inode
, struct file
*filp
)
36 /* enforce read-only access to this chrdev */
37 if ((filp
->f_mode
& FMODE_READ
) == 0)
39 if ((filp
->f_mode
& FMODE_WRITE
) != 0)
45 static atomic_t host_sleep_count
= ATOMIC_INIT(0);
47 static ssize_t
rng_dev_read (struct file
*filp
, char __user
*buf
, size_t size
,
51 int n
, ret
= 0, have_data
;
54 n
= os_read_file(random_fd
, &data
, sizeof(data
));
57 while (have_data
&& size
) {
58 if (put_user((u8
) data
, buf
++)) {
59 ret
= ret
? : -EFAULT
;
68 else if (n
== -EAGAIN
) {
69 DECLARE_WAITQUEUE(wait
, current
);
71 if (filp
->f_flags
& O_NONBLOCK
)
72 return ret
? : -EAGAIN
;
74 atomic_inc(&host_sleep_count
);
75 reactivate_fd(random_fd
, RANDOM_IRQ
);
76 add_sigio_fd(random_fd
);
78 add_wait_queue(&host_read_wait
, &wait
);
79 set_current_state(TASK_INTERRUPTIBLE
);
82 remove_wait_queue(&host_read_wait
, &wait
);
84 if (atomic_dec_and_test(&host_sleep_count
)) {
85 ignore_sigio_fd(random_fd
);
86 deactivate_fd(random_fd
, RANDOM_IRQ
);
92 if (signal_pending (current
))
93 return ret
? : -ERESTARTSYS
;
98 static const struct file_operations rng_chrdev_ops
= {
100 .open
= rng_dev_open
,
101 .read
= rng_dev_read
,
102 .llseek
= noop_llseek
,
105 /* rng_init shouldn't be called more than once at boot time */
106 static struct miscdevice rng_miscdev
= {
112 static irqreturn_t
random_interrupt(int irq
, void *data
)
114 wake_up(&host_read_wait
);
120 * rng_init - initialize RNG module
122 static int __init
rng_init (void)
126 err
= os_open_file("/dev/random", of_read(OPENFLAGS()), 0);
132 err
= um_request_irq(RANDOM_IRQ
, random_fd
, IRQ_READ
, random_interrupt
,
135 goto err_out_cleanup_hw
;
137 sigio_broken(random_fd
, 1);
139 err
= misc_register (&rng_miscdev
);
141 printk (KERN_ERR RNG_MODULE_NAME
": misc device register "
143 goto err_out_cleanup_hw
;
149 os_close_file(random_fd
);
155 * rng_cleanup - shutdown RNG module
157 static void __exit
rng_cleanup (void)
159 os_close_file(random_fd
);
160 misc_deregister (&rng_miscdev
);
163 module_init (rng_init
);
164 module_exit (rng_cleanup
);
166 MODULE_DESCRIPTION("UML Host Random Number Generator (RNG) driver");
167 MODULE_LICENSE("GPL");