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