172 lines
3.7 KiB
C
172 lines
3.7 KiB
C
/* Copyright (C) 2005 - 2008 Jeff Dike <jdike@{linux.intel,addtoit}.com> */
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/* Much of this ripped from drivers/char/hw_random.c, see there for other
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* copyright.
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*
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* This software may be used and distributed according to the terms
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* of the GNU General Public License, incorporated herein by reference.
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*/
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#include <linux/sched.h>
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#include <linux/smp_lock.h>
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/interrupt.h>
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#include <linux/miscdevice.h>
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#include <linux/delay.h>
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#include <asm/uaccess.h>
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#include "irq_kern.h"
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#include "os.h"
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/*
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* core module and version information
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*/
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#define RNG_VERSION "1.0.0"
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#define RNG_MODULE_NAME "hw_random"
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#define RNG_MISCDEV_MINOR 183 /* official */
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/* Changed at init time, in the non-modular case, and at module load
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* time, in the module case. Presumably, the module subsystem
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* protects against a module being loaded twice at the same time.
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*/
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static int random_fd = -1;
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static DECLARE_WAIT_QUEUE_HEAD(host_read_wait);
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static int rng_dev_open (struct inode *inode, struct file *filp)
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{
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cycle_kernel_lock();
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/* enforce read-only access to this chrdev */
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if ((filp->f_mode & FMODE_READ) == 0)
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return -EINVAL;
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if ((filp->f_mode & FMODE_WRITE) != 0)
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return -EINVAL;
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return 0;
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}
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static atomic_t host_sleep_count = ATOMIC_INIT(0);
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static ssize_t rng_dev_read (struct file *filp, char __user *buf, size_t size,
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loff_t *offp)
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{
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u32 data;
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int n, ret = 0, have_data;
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while (size) {
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n = os_read_file(random_fd, &data, sizeof(data));
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if (n > 0) {
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have_data = n;
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while (have_data && size) {
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if (put_user((u8) data, buf++)) {
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ret = ret ? : -EFAULT;
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break;
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}
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size--;
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ret++;
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have_data--;
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data >>= 8;
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}
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}
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else if (n == -EAGAIN) {
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DECLARE_WAITQUEUE(wait, current);
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if (filp->f_flags & O_NONBLOCK)
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return ret ? : -EAGAIN;
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atomic_inc(&host_sleep_count);
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reactivate_fd(random_fd, RANDOM_IRQ);
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add_sigio_fd(random_fd);
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add_wait_queue(&host_read_wait, &wait);
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set_task_state(current, TASK_INTERRUPTIBLE);
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schedule();
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set_task_state(current, TASK_RUNNING);
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remove_wait_queue(&host_read_wait, &wait);
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if (atomic_dec_and_test(&host_sleep_count)) {
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ignore_sigio_fd(random_fd);
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deactivate_fd(random_fd, RANDOM_IRQ);
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}
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}
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else
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return n;
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if (signal_pending (current))
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return ret ? : -ERESTARTSYS;
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}
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return ret;
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}
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static const struct file_operations rng_chrdev_ops = {
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.owner = THIS_MODULE,
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.open = rng_dev_open,
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.read = rng_dev_read,
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};
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/* rng_init shouldn't be called more than once at boot time */
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static struct miscdevice rng_miscdev = {
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RNG_MISCDEV_MINOR,
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RNG_MODULE_NAME,
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&rng_chrdev_ops,
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};
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static irqreturn_t random_interrupt(int irq, void *data)
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{
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wake_up(&host_read_wait);
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return IRQ_HANDLED;
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}
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/*
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* rng_init - initialize RNG module
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*/
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static int __init rng_init (void)
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{
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int err;
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err = os_open_file("/dev/random", of_read(OPENFLAGS()), 0);
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if (err < 0)
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goto out;
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random_fd = err;
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err = um_request_irq(RANDOM_IRQ, random_fd, IRQ_READ, random_interrupt,
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IRQF_DISABLED | IRQF_SAMPLE_RANDOM, "random",
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NULL);
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if (err)
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goto err_out_cleanup_hw;
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sigio_broken(random_fd, 1);
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err = misc_register (&rng_miscdev);
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if (err) {
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printk (KERN_ERR RNG_MODULE_NAME ": misc device register "
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"failed\n");
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goto err_out_cleanup_hw;
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}
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out:
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return err;
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err_out_cleanup_hw:
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os_close_file(random_fd);
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random_fd = -1;
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goto out;
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}
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/*
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* rng_cleanup - shutdown RNG module
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*/
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static void __exit rng_cleanup (void)
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{
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os_close_file(random_fd);
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misc_deregister (&rng_miscdev);
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}
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module_init (rng_init);
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module_exit (rng_cleanup);
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MODULE_DESCRIPTION("UML Host Random Number Generator (RNG) driver");
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MODULE_LICENSE("GPL");
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