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