Merge tag 'locking-urgent-2020-08-15' of git://git.kernel.org/pub/scm/linux/kernel...
[linux/fpc-iii.git] / arch / um / drivers / random.c
blobce115fce52f02acf6c609a929db54ecdb27e5520
1 /* Copyright (C) 2005 - 2008 Jeff Dike <jdike@{linux.intel,addtoit}.com> */
3 /* Much of this ripped from drivers/char/hw_random.c, see there for other
4 * copyright.
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/delay.h>
15 #include <linux/uaccess.h>
16 #include <init.h>
17 #include <irq_kern.h>
18 #include <os.h>
21 * core module and version information
23 #define RNG_VERSION "1.0.0"
24 #define RNG_MODULE_NAME "hw_random"
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.
30 static int random_fd = -1;
31 static DECLARE_WAIT_QUEUE_HEAD(host_read_wait);
33 static int rng_dev_open (struct inode *inode, struct file *filp)
35 /* enforce read-only access to this chrdev */
36 if ((filp->f_mode & FMODE_READ) == 0)
37 return -EINVAL;
38 if ((filp->f_mode & FMODE_WRITE) != 0)
39 return -EINVAL;
41 return 0;
44 static atomic_t host_sleep_count = ATOMIC_INIT(0);
46 static ssize_t rng_dev_read (struct file *filp, char __user *buf, size_t size,
47 loff_t *offp)
49 u32 data;
50 int n, ret = 0, have_data;
52 while (size) {
53 n = os_read_file(random_fd, &data, sizeof(data));
54 if (n > 0) {
55 have_data = n;
56 while (have_data && size) {
57 if (put_user((u8) data, buf++)) {
58 ret = ret ? : -EFAULT;
59 break;
61 size--;
62 ret++;
63 have_data--;
64 data >>= 8;
67 else if (n == -EAGAIN) {
68 DECLARE_WAITQUEUE(wait, current);
70 if (filp->f_flags & O_NONBLOCK)
71 return ret ? : -EAGAIN;
73 atomic_inc(&host_sleep_count);
74 add_sigio_fd(random_fd);
76 add_wait_queue(&host_read_wait, &wait);
77 set_current_state(TASK_INTERRUPTIBLE);
79 schedule();
80 remove_wait_queue(&host_read_wait, &wait);
82 if (atomic_dec_and_test(&host_sleep_count)) {
83 ignore_sigio_fd(random_fd);
84 deactivate_fd(random_fd, RANDOM_IRQ);
87 else
88 return n;
90 if (signal_pending (current))
91 return ret ? : -ERESTARTSYS;
93 return ret;
96 static const struct file_operations rng_chrdev_ops = {
97 .owner = THIS_MODULE,
98 .open = rng_dev_open,
99 .read = rng_dev_read,
100 .llseek = noop_llseek,
103 /* rng_init shouldn't be called more than once at boot time */
104 static struct miscdevice rng_miscdev = {
105 HWRNG_MINOR,
106 RNG_MODULE_NAME,
107 &rng_chrdev_ops,
110 static irqreturn_t random_interrupt(int irq, void *data)
112 wake_up(&host_read_wait);
114 return IRQ_HANDLED;
118 * rng_init - initialize RNG module
120 static int __init rng_init (void)
122 int err;
124 err = os_open_file("/dev/random", of_read(OPENFLAGS()), 0);
125 if (err < 0)
126 goto out;
128 random_fd = err;
130 err = um_request_irq(RANDOM_IRQ, random_fd, IRQ_READ, random_interrupt,
131 0, "random", NULL);
132 if (err)
133 goto err_out_cleanup_hw;
135 sigio_broken(random_fd, 1);
137 err = misc_register (&rng_miscdev);
138 if (err) {
139 printk (KERN_ERR RNG_MODULE_NAME ": misc device register "
140 "failed\n");
141 goto err_out_cleanup_hw;
143 out:
144 return err;
146 err_out_cleanup_hw:
147 os_close_file(random_fd);
148 random_fd = -1;
149 goto out;
153 * rng_cleanup - shutdown RNG module
156 static void cleanup(void)
158 free_irq_by_fd(random_fd);
159 os_close_file(random_fd);
162 static void __exit rng_cleanup(void)
164 os_close_file(random_fd);
165 misc_deregister (&rng_miscdev);
168 module_init (rng_init);
169 module_exit (rng_cleanup);
170 __uml_exitcall(cleanup);
172 MODULE_DESCRIPTION("UML Host Random Number Generator (RNG) driver");
173 MODULE_LICENSE("GPL");