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3d88958e JD |
1 | /* Copyright (C) 2005 - 2008 Jeff Dike <jdike@{linux.intel,addtoit}.com> */ |
2 | ||
567b5650 PBG |
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 | */ | |
174cd4b1 | 9 | #include <linux/sched/signal.h> |
1da177e4 LT |
10 | #include <linux/module.h> |
11 | #include <linux/fs.h> | |
5d33e4d7 | 12 | #include <linux/interrupt.h> |
1da177e4 LT |
13 | #include <linux/miscdevice.h> |
14 | #include <linux/delay.h> | |
7c0f6ba6 | 15 | #include <linux/uaccess.h> |
ff6a1798 | 16 | #include <init.h> |
37185b33 AV |
17 | #include <irq_kern.h> |
18 | #include <os.h> | |
1da177e4 LT |
19 | |
20 | /* | |
21 | * core module and version information | |
22 | */ | |
23 | #define RNG_VERSION "1.0.0" | |
5d33e4d7 | 24 | #define RNG_MODULE_NAME "hw_random" |
1da177e4 LT |
25 | |
26 | #define RNG_MISCDEV_MINOR 183 /* official */ | |
27 | ||
730760e9 JD |
28 | /* Changed at init time, in the non-modular case, and at module load |
29 | * time, in the module case. Presumably, the module subsystem | |
30 | * protects against a module being loaded twice at the same time. | |
31 | */ | |
1da177e4 | 32 | static int random_fd = -1; |
5d33e4d7 | 33 | static DECLARE_WAIT_QUEUE_HEAD(host_read_wait); |
1da177e4 LT |
34 | |
35 | static int rng_dev_open (struct inode *inode, struct file *filp) | |
36 | { | |
37 | /* enforce read-only access to this chrdev */ | |
38 | if ((filp->f_mode & FMODE_READ) == 0) | |
39 | return -EINVAL; | |
3d88958e | 40 | if ((filp->f_mode & FMODE_WRITE) != 0) |
1da177e4 LT |
41 | return -EINVAL; |
42 | ||
43 | return 0; | |
44 | } | |
45 | ||
5d33e4d7 JD |
46 | static atomic_t host_sleep_count = ATOMIC_INIT(0); |
47 | ||
1da177e4 | 48 | static ssize_t rng_dev_read (struct file *filp, char __user *buf, size_t size, |
3d88958e | 49 | loff_t *offp) |
1da177e4 | 50 | { |
3d88958e JD |
51 | u32 data; |
52 | int n, ret = 0, have_data; | |
53 | ||
54 | while (size) { | |
55 | n = os_read_file(random_fd, &data, sizeof(data)); | |
56 | if (n > 0) { | |
57 | have_data = n; | |
58 | while (have_data && size) { | |
59 | if (put_user((u8) data, buf++)) { | |
60 | ret = ret ? : -EFAULT; | |
61 | break; | |
62 | } | |
63 | size--; | |
64 | ret++; | |
65 | have_data--; | |
66 | data >>= 8; | |
67 | } | |
68 | } | |
69 | else if (n == -EAGAIN) { | |
5d33e4d7 JD |
70 | DECLARE_WAITQUEUE(wait, current); |
71 | ||
3d88958e JD |
72 | if (filp->f_flags & O_NONBLOCK) |
73 | return ret ? : -EAGAIN; | |
1da177e4 | 74 | |
5d33e4d7 | 75 | atomic_inc(&host_sleep_count); |
5d33e4d7 JD |
76 | add_sigio_fd(random_fd); |
77 | ||
78 | add_wait_queue(&host_read_wait, &wait); | |
642fa448 | 79 | set_current_state(TASK_INTERRUPTIBLE); |
5d33e4d7 JD |
80 | |
81 | schedule(); | |
5d33e4d7 JD |
82 | remove_wait_queue(&host_read_wait, &wait); |
83 | ||
84 | if (atomic_dec_and_test(&host_sleep_count)) { | |
85 | ignore_sigio_fd(random_fd); | |
86 | deactivate_fd(random_fd, RANDOM_IRQ); | |
87 | } | |
3d88958e JD |
88 | } |
89 | else | |
90 | return n; | |
91 | ||
1da177e4 LT |
92 | if (signal_pending (current)) |
93 | return ret ? : -ERESTARTSYS; | |
94 | } | |
95 | return ret; | |
96 | } | |
97 | ||
5e7672ec | 98 | static const struct file_operations rng_chrdev_ops = { |
1da177e4 LT |
99 | .owner = THIS_MODULE, |
100 | .open = rng_dev_open, | |
101 | .read = rng_dev_read, | |
6038f373 | 102 | .llseek = noop_llseek, |
1da177e4 LT |
103 | }; |
104 | ||
99b0278f | 105 | /* rng_init shouldn't be called more than once at boot time */ |
1da177e4 LT |
106 | static struct miscdevice rng_miscdev = { |
107 | RNG_MISCDEV_MINOR, | |
108 | RNG_MODULE_NAME, | |
109 | &rng_chrdev_ops, | |
110 | }; | |
111 | ||
5d33e4d7 JD |
112 | static irqreturn_t random_interrupt(int irq, void *data) |
113 | { | |
114 | wake_up(&host_read_wait); | |
115 | ||
116 | return IRQ_HANDLED; | |
117 | } | |
118 | ||
1da177e4 LT |
119 | /* |
120 | * rng_init - initialize RNG module | |
121 | */ | |
122 | static int __init rng_init (void) | |
123 | { | |
124 | int err; | |
125 | ||
3d88958e JD |
126 | err = os_open_file("/dev/random", of_read(OPENFLAGS()), 0); |
127 | if (err < 0) | |
128 | goto out; | |
1da177e4 | 129 | |
3d88958e | 130 | random_fd = err; |
1da177e4 | 131 | |
5d33e4d7 | 132 | err = um_request_irq(RANDOM_IRQ, random_fd, IRQ_READ, random_interrupt, |
aab94460 | 133 | 0, "random", NULL); |
3d88958e | 134 | if (err) |
1da177e4 LT |
135 | goto err_out_cleanup_hw; |
136 | ||
5d33e4d7 JD |
137 | sigio_broken(random_fd, 1); |
138 | ||
1da177e4 LT |
139 | err = misc_register (&rng_miscdev); |
140 | if (err) { | |
3d88958e JD |
141 | printk (KERN_ERR RNG_MODULE_NAME ": misc device register " |
142 | "failed\n"); | |
1da177e4 LT |
143 | goto err_out_cleanup_hw; |
144 | } | |
3d88958e JD |
145 | out: |
146 | return err; | |
1da177e4 | 147 | |
3d88958e | 148 | err_out_cleanup_hw: |
5d33e4d7 | 149 | os_close_file(random_fd); |
3d88958e JD |
150 | random_fd = -1; |
151 | goto out; | |
1da177e4 LT |
152 | } |
153 | ||
154 | /* | |
155 | * rng_cleanup - shutdown RNG module | |
156 | */ | |
ff6a1798 AI |
157 | |
158 | static void cleanup(void) | |
159 | { | |
160 | free_irq_by_fd(random_fd); | |
161 | os_close_file(random_fd); | |
162 | } | |
163 | ||
164 | static void __exit rng_cleanup(void) | |
1da177e4 | 165 | { |
5d33e4d7 | 166 | os_close_file(random_fd); |
1da177e4 LT |
167 | misc_deregister (&rng_miscdev); |
168 | } | |
169 | ||
170 | module_init (rng_init); | |
171 | module_exit (rng_cleanup); | |
ff6a1798 | 172 | __uml_exitcall(cleanup); |
567b5650 PBG |
173 | |
174 | MODULE_DESCRIPTION("UML Host Random Number Generator (RNG) driver"); | |
175 | MODULE_LICENSE("GPL"); |