Commit | Line | Data |
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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> |
7eb500d1 | 10 | #include <linux/smp_lock.h> |
1da177e4 LT |
11 | #include <linux/module.h> |
12 | #include <linux/fs.h> | |
5d33e4d7 | 13 | #include <linux/interrupt.h> |
1da177e4 LT |
14 | #include <linux/miscdevice.h> |
15 | #include <linux/delay.h> | |
16 | #include <asm/uaccess.h> | |
5d33e4d7 | 17 | #include "irq_kern.h" |
1da177e4 LT |
18 | #include "os.h" |
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 | { | |
7eb500d1 AB |
37 | cycle_kernel_lock(); |
38 | ||
1da177e4 LT |
39 | /* enforce read-only access to this chrdev */ |
40 | if ((filp->f_mode & FMODE_READ) == 0) | |
41 | return -EINVAL; | |
3d88958e | 42 | if ((filp->f_mode & FMODE_WRITE) != 0) |
1da177e4 LT |
43 | return -EINVAL; |
44 | ||
45 | return 0; | |
46 | } | |
47 | ||
5d33e4d7 JD |
48 | static atomic_t host_sleep_count = ATOMIC_INIT(0); |
49 | ||
1da177e4 | 50 | static ssize_t rng_dev_read (struct file *filp, char __user *buf, size_t size, |
3d88958e | 51 | loff_t *offp) |
1da177e4 | 52 | { |
3d88958e JD |
53 | u32 data; |
54 | int n, ret = 0, have_data; | |
55 | ||
56 | while (size) { | |
57 | n = os_read_file(random_fd, &data, sizeof(data)); | |
58 | if (n > 0) { | |
59 | have_data = n; | |
60 | while (have_data && size) { | |
61 | if (put_user((u8) data, buf++)) { | |
62 | ret = ret ? : -EFAULT; | |
63 | break; | |
64 | } | |
65 | size--; | |
66 | ret++; | |
67 | have_data--; | |
68 | data >>= 8; | |
69 | } | |
70 | } | |
71 | else if (n == -EAGAIN) { | |
5d33e4d7 JD |
72 | DECLARE_WAITQUEUE(wait, current); |
73 | ||
3d88958e JD |
74 | if (filp->f_flags & O_NONBLOCK) |
75 | return ret ? : -EAGAIN; | |
1da177e4 | 76 | |
5d33e4d7 JD |
77 | atomic_inc(&host_sleep_count); |
78 | reactivate_fd(random_fd, RANDOM_IRQ); | |
79 | add_sigio_fd(random_fd); | |
80 | ||
81 | add_wait_queue(&host_read_wait, &wait); | |
82 | set_task_state(current, TASK_INTERRUPTIBLE); | |
83 | ||
84 | schedule(); | |
85 | set_task_state(current, TASK_RUNNING); | |
86 | remove_wait_queue(&host_read_wait, &wait); | |
87 | ||
88 | if (atomic_dec_and_test(&host_sleep_count)) { | |
89 | ignore_sigio_fd(random_fd); | |
90 | deactivate_fd(random_fd, RANDOM_IRQ); | |
91 | } | |
3d88958e JD |
92 | } |
93 | else | |
94 | return n; | |
95 | ||
1da177e4 LT |
96 | if (signal_pending (current)) |
97 | return ret ? : -ERESTARTSYS; | |
98 | } | |
99 | return ret; | |
100 | } | |
101 | ||
5e7672ec | 102 | static const struct file_operations rng_chrdev_ops = { |
1da177e4 LT |
103 | .owner = THIS_MODULE, |
104 | .open = rng_dev_open, | |
105 | .read = rng_dev_read, | |
106 | }; | |
107 | ||
99b0278f | 108 | /* rng_init shouldn't be called more than once at boot time */ |
1da177e4 LT |
109 | static struct miscdevice rng_miscdev = { |
110 | RNG_MISCDEV_MINOR, | |
111 | RNG_MODULE_NAME, | |
112 | &rng_chrdev_ops, | |
113 | }; | |
114 | ||
5d33e4d7 JD |
115 | static irqreturn_t random_interrupt(int irq, void *data) |
116 | { | |
117 | wake_up(&host_read_wait); | |
118 | ||
119 | return IRQ_HANDLED; | |
120 | } | |
121 | ||
1da177e4 LT |
122 | /* |
123 | * rng_init - initialize RNG module | |
124 | */ | |
125 | static int __init rng_init (void) | |
126 | { | |
127 | int err; | |
128 | ||
3d88958e JD |
129 | err = os_open_file("/dev/random", of_read(OPENFLAGS()), 0); |
130 | if (err < 0) | |
131 | goto out; | |
1da177e4 | 132 | |
3d88958e | 133 | random_fd = err; |
1da177e4 | 134 | |
5d33e4d7 JD |
135 | err = um_request_irq(RANDOM_IRQ, random_fd, IRQ_READ, random_interrupt, |
136 | IRQF_DISABLED | IRQF_SAMPLE_RANDOM, "random", | |
137 | NULL); | |
3d88958e | 138 | if (err) |
1da177e4 LT |
139 | goto err_out_cleanup_hw; |
140 | ||
5d33e4d7 JD |
141 | sigio_broken(random_fd, 1); |
142 | ||
1da177e4 LT |
143 | err = misc_register (&rng_miscdev); |
144 | if (err) { | |
3d88958e JD |
145 | printk (KERN_ERR RNG_MODULE_NAME ": misc device register " |
146 | "failed\n"); | |
1da177e4 LT |
147 | goto err_out_cleanup_hw; |
148 | } | |
3d88958e JD |
149 | out: |
150 | return err; | |
1da177e4 | 151 | |
3d88958e | 152 | err_out_cleanup_hw: |
5d33e4d7 | 153 | os_close_file(random_fd); |
3d88958e JD |
154 | random_fd = -1; |
155 | goto out; | |
1da177e4 LT |
156 | } |
157 | ||
158 | /* | |
159 | * rng_cleanup - shutdown RNG module | |
160 | */ | |
161 | static void __exit rng_cleanup (void) | |
162 | { | |
5d33e4d7 | 163 | os_close_file(random_fd); |
1da177e4 LT |
164 | misc_deregister (&rng_miscdev); |
165 | } | |
166 | ||
167 | module_init (rng_init); | |
168 | module_exit (rng_cleanup); | |
567b5650 PBG |
169 | |
170 | MODULE_DESCRIPTION("UML Host Random Number Generator (RNG) driver"); | |
171 | MODULE_LICENSE("GPL"); |