1*4882a593Smuzhiyun /* Copyright (C) 2005 - 2008 Jeff Dike <jdike@{linux.intel,addtoit}.com> */
2*4882a593Smuzhiyun
3*4882a593Smuzhiyun /* Much of this ripped from drivers/char/hw_random.c, see there for other
4*4882a593Smuzhiyun * copyright.
5*4882a593Smuzhiyun *
6*4882a593Smuzhiyun * This software may be used and distributed according to the terms
7*4882a593Smuzhiyun * of the GNU General Public License, incorporated herein by reference.
8*4882a593Smuzhiyun */
9*4882a593Smuzhiyun #include <linux/sched/signal.h>
10*4882a593Smuzhiyun #include <linux/module.h>
11*4882a593Smuzhiyun #include <linux/fs.h>
12*4882a593Smuzhiyun #include <linux/interrupt.h>
13*4882a593Smuzhiyun #include <linux/miscdevice.h>
14*4882a593Smuzhiyun #include <linux/hw_random.h>
15*4882a593Smuzhiyun #include <linux/delay.h>
16*4882a593Smuzhiyun #include <linux/uaccess.h>
17*4882a593Smuzhiyun #include <init.h>
18*4882a593Smuzhiyun #include <irq_kern.h>
19*4882a593Smuzhiyun #include <os.h>
20*4882a593Smuzhiyun
21*4882a593Smuzhiyun /*
22*4882a593Smuzhiyun * core module information
23*4882a593Smuzhiyun */
24*4882a593Smuzhiyun #define RNG_MODULE_NAME "hw_random"
25*4882a593Smuzhiyun
26*4882a593Smuzhiyun /* Changed at init time, in the non-modular case, and at module load
27*4882a593Smuzhiyun * time, in the module case. Presumably, the module subsystem
28*4882a593Smuzhiyun * protects against a module being loaded twice at the same time.
29*4882a593Smuzhiyun */
30*4882a593Smuzhiyun static int random_fd = -1;
31*4882a593Smuzhiyun static struct hwrng hwrng;
32*4882a593Smuzhiyun static DECLARE_COMPLETION(have_data);
33*4882a593Smuzhiyun
rng_dev_read(struct hwrng * rng,void * buf,size_t max,bool block)34*4882a593Smuzhiyun static int rng_dev_read(struct hwrng *rng, void *buf, size_t max, bool block)
35*4882a593Smuzhiyun {
36*4882a593Smuzhiyun int ret;
37*4882a593Smuzhiyun
38*4882a593Smuzhiyun for (;;) {
39*4882a593Smuzhiyun ret = os_read_file(random_fd, buf, max);
40*4882a593Smuzhiyun if (block && ret == -EAGAIN) {
41*4882a593Smuzhiyun add_sigio_fd(random_fd);
42*4882a593Smuzhiyun
43*4882a593Smuzhiyun ret = wait_for_completion_killable(&have_data);
44*4882a593Smuzhiyun
45*4882a593Smuzhiyun ignore_sigio_fd(random_fd);
46*4882a593Smuzhiyun deactivate_fd(random_fd, RANDOM_IRQ);
47*4882a593Smuzhiyun
48*4882a593Smuzhiyun if (ret < 0)
49*4882a593Smuzhiyun break;
50*4882a593Smuzhiyun } else {
51*4882a593Smuzhiyun break;
52*4882a593Smuzhiyun }
53*4882a593Smuzhiyun }
54*4882a593Smuzhiyun
55*4882a593Smuzhiyun return ret != -EAGAIN ? ret : 0;
56*4882a593Smuzhiyun }
57*4882a593Smuzhiyun
random_interrupt(int irq,void * data)58*4882a593Smuzhiyun static irqreturn_t random_interrupt(int irq, void *data)
59*4882a593Smuzhiyun {
60*4882a593Smuzhiyun complete(&have_data);
61*4882a593Smuzhiyun
62*4882a593Smuzhiyun return IRQ_HANDLED;
63*4882a593Smuzhiyun }
64*4882a593Smuzhiyun
65*4882a593Smuzhiyun /*
66*4882a593Smuzhiyun * rng_init - initialize RNG module
67*4882a593Smuzhiyun */
rng_init(void)68*4882a593Smuzhiyun static int __init rng_init (void)
69*4882a593Smuzhiyun {
70*4882a593Smuzhiyun int err;
71*4882a593Smuzhiyun
72*4882a593Smuzhiyun err = os_open_file("/dev/random", of_read(OPENFLAGS()), 0);
73*4882a593Smuzhiyun if (err < 0)
74*4882a593Smuzhiyun goto out;
75*4882a593Smuzhiyun
76*4882a593Smuzhiyun random_fd = err;
77*4882a593Smuzhiyun err = um_request_irq(RANDOM_IRQ, random_fd, IRQ_READ, random_interrupt,
78*4882a593Smuzhiyun 0, "random", NULL);
79*4882a593Smuzhiyun if (err)
80*4882a593Smuzhiyun goto err_out_cleanup_hw;
81*4882a593Smuzhiyun
82*4882a593Smuzhiyun sigio_broken(random_fd, 1);
83*4882a593Smuzhiyun hwrng.name = RNG_MODULE_NAME;
84*4882a593Smuzhiyun hwrng.read = rng_dev_read;
85*4882a593Smuzhiyun hwrng.quality = 1024;
86*4882a593Smuzhiyun
87*4882a593Smuzhiyun err = hwrng_register(&hwrng);
88*4882a593Smuzhiyun if (err) {
89*4882a593Smuzhiyun pr_err(RNG_MODULE_NAME " registering failed (%d)\n", err);
90*4882a593Smuzhiyun goto err_out_cleanup_hw;
91*4882a593Smuzhiyun }
92*4882a593Smuzhiyun out:
93*4882a593Smuzhiyun return err;
94*4882a593Smuzhiyun
95*4882a593Smuzhiyun err_out_cleanup_hw:
96*4882a593Smuzhiyun os_close_file(random_fd);
97*4882a593Smuzhiyun random_fd = -1;
98*4882a593Smuzhiyun goto out;
99*4882a593Smuzhiyun }
100*4882a593Smuzhiyun
101*4882a593Smuzhiyun /*
102*4882a593Smuzhiyun * rng_cleanup - shutdown RNG module
103*4882a593Smuzhiyun */
104*4882a593Smuzhiyun
cleanup(void)105*4882a593Smuzhiyun static void cleanup(void)
106*4882a593Smuzhiyun {
107*4882a593Smuzhiyun free_irq_by_fd(random_fd);
108*4882a593Smuzhiyun os_close_file(random_fd);
109*4882a593Smuzhiyun }
110*4882a593Smuzhiyun
rng_cleanup(void)111*4882a593Smuzhiyun static void __exit rng_cleanup(void)
112*4882a593Smuzhiyun {
113*4882a593Smuzhiyun hwrng_unregister(&hwrng);
114*4882a593Smuzhiyun os_close_file(random_fd);
115*4882a593Smuzhiyun }
116*4882a593Smuzhiyun
117*4882a593Smuzhiyun module_init (rng_init);
118*4882a593Smuzhiyun module_exit (rng_cleanup);
119*4882a593Smuzhiyun __uml_exitcall(cleanup);
120*4882a593Smuzhiyun
121*4882a593Smuzhiyun MODULE_DESCRIPTION("UML Host Random Number Generator (RNG) driver");
122*4882a593Smuzhiyun MODULE_LICENSE("GPL");
123