| /* 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 <linux/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"); |