[deliverable/linux.git] / arch / um / drivers / random.c

/* 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/smp_lock.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)
{
	cycle_kernel_lock();

	/* 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();
			set_task_state(current, TASK_RUNNING);
			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,
};

/* 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,
			     IRQF_DISABLED | IRQF_SAMPLE_RANDOM, "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");
Commit	Line	Data
3d88958e JD	1	/* Copyright (C) 2005 - 2008 Jeff Dike <jdike@{linux.intel,addtoit}.com> */
3d88958e JD	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>
1da177e4 LT	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();
7eb500d1 AB	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);
5d33e4d7 JD	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);
5d33e4d7 JD	73
3d88958e JD	74	if (filp->f_flags & O_NONBLOCK)
3d88958e JD	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;
1da177e4 LT	140
5d33e4d7 JD	141	sigio_broken(random_fd, 1);
5d33e4d7 JD	142
1da177e4 LT	143	err = misc_register (&rng_miscdev);
1da177e4 LT	144	if (err) {
3d88958e JD	145	printk (KERN_ERR RNG_MODULE_NAME ": misc device register "
3d88958e JD	146	"failed\n");
1da177e4 LT	147	goto err_out_cleanup_hw;
1da177e4 LT	148	}
3d88958e JD	149	out:
3d88958e JD	150	return err;
1da177e4	151
3d88958e	152	err_out_cleanup_hw:
5d33e4d7	153	os_close_file(random_fd);
3d88958e JD	154	random_fd = -1;
3d88958e JD	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");