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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 | */ | |
8192ab42 | 9 | #include <linux/sched.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> | |
15 | #include <asm/uaccess.h> | |
37185b33 AV |
16 | #include <irq_kern.h> |
17 | #include <os.h> | |
1da177e4 LT |
18 | |
19 | /* | |
20 | * core module and version information | |
21 | */ | |
22 | #define RNG_VERSION "1.0.0" | |
5d33e4d7 | 23 | #define RNG_MODULE_NAME "hw_random" |
1da177e4 LT |
24 | |
25 | #define RNG_MISCDEV_MINOR 183 /* official */ | |
26 | ||
730760e9 JD |
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. | |
30 | */ | |
1da177e4 | 31 | static int random_fd = -1; |
5d33e4d7 | 32 | static DECLARE_WAIT_QUEUE_HEAD(host_read_wait); |
1da177e4 LT |
33 | |
34 | static int rng_dev_open (struct inode *inode, struct file *filp) | |
35 | { | |
36 | /* enforce read-only access to this chrdev */ | |
37 | if ((filp->f_mode & FMODE_READ) == 0) | |
38 | return -EINVAL; | |
3d88958e | 39 | if ((filp->f_mode & FMODE_WRITE) != 0) |
1da177e4 LT |
40 | return -EINVAL; |
41 | ||
42 | return 0; | |
43 | } | |
44 | ||
5d33e4d7 JD |
45 | static atomic_t host_sleep_count = ATOMIC_INIT(0); |
46 | ||
1da177e4 | 47 | static ssize_t rng_dev_read (struct file *filp, char __user *buf, size_t size, |
3d88958e | 48 | loff_t *offp) |
1da177e4 | 49 | { |
3d88958e JD |
50 | u32 data; |
51 | int n, ret = 0, have_data; | |
52 | ||
53 | while (size) { | |
54 | n = os_read_file(random_fd, &data, sizeof(data)); | |
55 | if (n > 0) { | |
56 | have_data = n; | |
57 | while (have_data && size) { | |
58 | if (put_user((u8) data, buf++)) { | |
59 | ret = ret ? : -EFAULT; | |
60 | break; | |
61 | } | |
62 | size--; | |
63 | ret++; | |
64 | have_data--; | |
65 | data >>= 8; | |
66 | } | |
67 | } | |
68 | else if (n == -EAGAIN) { | |
5d33e4d7 JD |
69 | DECLARE_WAITQUEUE(wait, current); |
70 | ||
3d88958e JD |
71 | if (filp->f_flags & O_NONBLOCK) |
72 | return ret ? : -EAGAIN; | |
1da177e4 | 73 | |
5d33e4d7 JD |
74 | atomic_inc(&host_sleep_count); |
75 | reactivate_fd(random_fd, RANDOM_IRQ); | |
76 | add_sigio_fd(random_fd); | |
77 | ||
78 | add_wait_queue(&host_read_wait, &wait); | |
79 | set_task_state(current, TASK_INTERRUPTIBLE); | |
80 | ||
81 | schedule(); | |
82 | set_task_state(current, TASK_RUNNING); | |
83 | remove_wait_queue(&host_read_wait, &wait); | |
84 | ||
85 | if (atomic_dec_and_test(&host_sleep_count)) { | |
86 | ignore_sigio_fd(random_fd); | |
87 | deactivate_fd(random_fd, RANDOM_IRQ); | |
88 | } | |
3d88958e JD |
89 | } |
90 | else | |
91 | return n; | |
92 | ||
1da177e4 LT |
93 | if (signal_pending (current)) |
94 | return ret ? : -ERESTARTSYS; | |
95 | } | |
96 | return ret; | |
97 | } | |
98 | ||
5e7672ec | 99 | static const struct file_operations rng_chrdev_ops = { |
1da177e4 LT |
100 | .owner = THIS_MODULE, |
101 | .open = rng_dev_open, | |
102 | .read = rng_dev_read, | |
6038f373 | 103 | .llseek = noop_llseek, |
1da177e4 LT |
104 | }; |
105 | ||
99b0278f | 106 | /* rng_init shouldn't be called more than once at boot time */ |
1da177e4 LT |
107 | static struct miscdevice rng_miscdev = { |
108 | RNG_MISCDEV_MINOR, | |
109 | RNG_MODULE_NAME, | |
110 | &rng_chrdev_ops, | |
111 | }; | |
112 | ||
5d33e4d7 JD |
113 | static irqreturn_t random_interrupt(int irq, void *data) |
114 | { | |
115 | wake_up(&host_read_wait); | |
116 | ||
117 | return IRQ_HANDLED; | |
118 | } | |
119 | ||
1da177e4 LT |
120 | /* |
121 | * rng_init - initialize RNG module | |
122 | */ | |
123 | static int __init rng_init (void) | |
124 | { | |
125 | int err; | |
126 | ||
3d88958e JD |
127 | err = os_open_file("/dev/random", of_read(OPENFLAGS()), 0); |
128 | if (err < 0) | |
129 | goto out; | |
1da177e4 | 130 | |
3d88958e | 131 | random_fd = err; |
1da177e4 | 132 | |
5d33e4d7 | 133 | err = um_request_irq(RANDOM_IRQ, random_fd, IRQ_READ, random_interrupt, |
aab94460 | 134 | 0, "random", NULL); |
3d88958e | 135 | if (err) |
1da177e4 LT |
136 | goto err_out_cleanup_hw; |
137 | ||
5d33e4d7 JD |
138 | sigio_broken(random_fd, 1); |
139 | ||
1da177e4 LT |
140 | err = misc_register (&rng_miscdev); |
141 | if (err) { | |
3d88958e JD |
142 | printk (KERN_ERR RNG_MODULE_NAME ": misc device register " |
143 | "failed\n"); | |
1da177e4 LT |
144 | goto err_out_cleanup_hw; |
145 | } | |
3d88958e JD |
146 | out: |
147 | return err; | |
1da177e4 | 148 | |
3d88958e | 149 | err_out_cleanup_hw: |
5d33e4d7 | 150 | os_close_file(random_fd); |
3d88958e JD |
151 | random_fd = -1; |
152 | goto out; | |
1da177e4 LT |
153 | } |
154 | ||
155 | /* | |
156 | * rng_cleanup - shutdown RNG module | |
157 | */ | |
158 | static void __exit rng_cleanup (void) | |
159 | { | |
5d33e4d7 | 160 | os_close_file(random_fd); |
1da177e4 LT |
161 | misc_deregister (&rng_miscdev); |
162 | } | |
163 | ||
164 | module_init (rng_init); | |
165 | module_exit (rng_cleanup); | |
567b5650 PBG |
166 | |
167 | MODULE_DESCRIPTION("UML Host Random Number Generator (RNG) driver"); | |
168 | MODULE_LICENSE("GPL"); |