--- /dev/null
+/*
+ Added support for the AMD Geode LX RNG
+ (c) Copyright 2004-2005 Advanced Micro Devices, Inc.
+
+ derived from
+
+ Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG)
+ (c) Copyright 2003 Red Hat Inc <jgarzik@redhat.com>
+
+ derived from
+
+ Hardware driver for the AMD 768 Random Number Generator (RNG)
+ (c) Copyright 2001 Red Hat Inc <alan@redhat.com>
+
+ derived from
+
+ Hardware driver for Intel i810 Random Number Generator (RNG)
+ Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com>
+ Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com>
+
+ Added generic RNG API
+ Copyright 2006 Michael Buesch <mbuesch@freenet.de>
+ Copyright 2005 (c) MontaVista Software, Inc.
+
+ Please read Documentation/hw_random.txt for details on use.
+
+ ----------------------------------------------------------
+ This software may be used and distributed according to the terms
+ of the GNU General Public License, incorporated herein by reference.
+
+ */
+
+
+#include <linux/device.h>
+#include <linux/hw_random.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/miscdevice.h>
+#include <linux/delay.h>
+#include <asm/uaccess.h>
+
+
+#define RNG_MODULE_NAME "hw_random"
+#define PFX RNG_MODULE_NAME ": "
+#define RNG_MISCDEV_MINOR 183 /* official */
+
+
+static struct hwrng *current_rng;
+static LIST_HEAD(rng_list);
+static DEFINE_MUTEX(rng_mutex);
+
+
+static inline int hwrng_init(struct hwrng *rng)
+{
+ if (!rng->init)
+ return 0;
+ return rng->init(rng);
+}
+
+static inline void hwrng_cleanup(struct hwrng *rng)
+{
+ if (rng && rng->cleanup)
+ rng->cleanup(rng);
+}
+
+static inline int hwrng_data_present(struct hwrng *rng)
+{
+ if (!rng->data_present)
+ return 1;
+ return rng->data_present(rng);
+}
+
+static inline int hwrng_data_read(struct hwrng *rng, u32 *data)
+{
+ return rng->data_read(rng, data);
+}
+
+
+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)
+ return -EINVAL;
+ return 0;
+}
+
+static ssize_t rng_dev_read(struct file *filp, char __user *buf,
+ size_t size, loff_t *offp)
+{
+ u32 data;
+ ssize_t ret = 0;
+ int i, err = 0;
+ int data_present;
+ int bytes_read;
+
+ while (size) {
+ err = -ERESTARTSYS;
+ if (mutex_lock_interruptible(&rng_mutex))
+ goto out;
+ if (!current_rng) {
+ mutex_unlock(&rng_mutex);
+ err = -ENODEV;
+ goto out;
+ }
+ if (filp->f_flags & O_NONBLOCK) {
+ data_present = hwrng_data_present(current_rng);
+ } else {
+ /* Some RNG require some time between data_reads to gather
+ * new entropy. Poll it.
+ */
+ for (i = 0; i < 20; i++) {
+ data_present = hwrng_data_present(current_rng);
+ if (data_present)
+ break;
+ udelay(10);
+ }
+ }
+ bytes_read = 0;
+ if (data_present)
+ bytes_read = hwrng_data_read(current_rng, &data);
+ mutex_unlock(&rng_mutex);
+
+ err = -EAGAIN;
+ if (!bytes_read && (filp->f_flags & O_NONBLOCK))
+ goto out;
+
+ err = -EFAULT;
+ while (bytes_read && size) {
+ if (put_user((u8)data, buf++))
+ goto out;
+ size--;
+ ret++;
+ bytes_read--;
+ data >>= 8;
+ }
+
+ if (need_resched())
+ schedule_timeout_interruptible(1);
+ err = -ERESTARTSYS;
+ if (signal_pending(current))
+ goto out;
+ }
+out:
+ return ret ? : err;
+}
+
+
+static const struct file_operations rng_chrdev_ops = {
+ .owner = THIS_MODULE,
+ .open = rng_dev_open,
+ .read = rng_dev_read,
+};
+
+static struct miscdevice rng_miscdev = {
+ .minor = RNG_MISCDEV_MINOR,
+ .name = RNG_MODULE_NAME,
+ .fops = &rng_chrdev_ops,
+};
+
+
+static ssize_t hwrng_attr_current_store(struct class_device *class,
+ const char *buf, size_t len)
+{
+ int err;
+ struct hwrng *rng;
+
+ err = mutex_lock_interruptible(&rng_mutex);
+ if (err)
+ return -ERESTARTSYS;
+ err = -ENODEV;
+ list_for_each_entry(rng, &rng_list, list) {
+ if (strcmp(rng->name, buf) == 0) {
+ if (rng == current_rng) {
+ err = 0;
+ break;
+ }
+ err = hwrng_init(rng);
+ if (err)
+ break;
+ hwrng_cleanup(current_rng);
+ current_rng = rng;
+ err = 0;
+ break;
+ }
+ }
+ mutex_unlock(&rng_mutex);
+
+ return err ? : len;
+}
+
+static ssize_t hwrng_attr_current_show(struct class_device *class,
+ char *buf)
+{
+ int err;
+ ssize_t ret;
+ const char *name = "none";
+
+ err = mutex_lock_interruptible(&rng_mutex);
+ if (err)
+ return -ERESTARTSYS;
+ if (current_rng)
+ name = current_rng->name;
+ ret = snprintf(buf, PAGE_SIZE, "%s\n", name);
+ mutex_unlock(&rng_mutex);
+
+ return ret;
+}
+
+static ssize_t hwrng_attr_available_show(struct class_device *class,
+ char *buf)
+{
+ int err;
+ ssize_t ret = 0;
+ struct hwrng *rng;
+
+ err = mutex_lock_interruptible(&rng_mutex);
+ if (err)
+ return -ERESTARTSYS;
+ buf[0] = '\0';
+ list_for_each_entry(rng, &rng_list, list) {
+ strncat(buf, rng->name, PAGE_SIZE - ret - 1);
+ ret += strlen(rng->name);
+ strncat(buf, " ", PAGE_SIZE - ret - 1);
+ ret++;
+ }
+ strncat(buf, "\n", PAGE_SIZE - ret - 1);
+ ret++;
+ mutex_unlock(&rng_mutex);
+
+ return ret;
+}
+
+static CLASS_DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR,
+ hwrng_attr_current_show,
+ hwrng_attr_current_store);
+static CLASS_DEVICE_ATTR(rng_available, S_IRUGO,
+ hwrng_attr_available_show,
+ NULL);
+
+
+static void unregister_miscdev(void)
+{
+ class_device_remove_file(rng_miscdev.class,
+ &class_device_attr_rng_available);
+ class_device_remove_file(rng_miscdev.class,
+ &class_device_attr_rng_current);
+ misc_deregister(&rng_miscdev);
+}
+
+static int register_miscdev(void)
+{
+ int err;
+
+ err = misc_register(&rng_miscdev);
+ if (err)
+ goto out;
+ err = class_device_create_file(rng_miscdev.class,
+ &class_device_attr_rng_current);
+ if (err)
+ goto err_misc_dereg;
+ err = class_device_create_file(rng_miscdev.class,
+ &class_device_attr_rng_available);
+ if (err)
+ goto err_remove_current;
+out:
+ return err;
+
+err_remove_current:
+ class_device_remove_file(rng_miscdev.class,
+ &class_device_attr_rng_current);
+err_misc_dereg:
+ misc_deregister(&rng_miscdev);
+ goto out;
+}
+
+int hwrng_register(struct hwrng *rng)
+{
+ int must_register_misc;
+ int err = -EINVAL;
+ struct hwrng *old_rng, *tmp;
+
+ if (rng->name == NULL ||
+ rng->data_read == NULL)
+ goto out;
+
+ mutex_lock(&rng_mutex);
+
+ /* Must not register two RNGs with the same name. */
+ err = -EEXIST;
+ list_for_each_entry(tmp, &rng_list, list) {
+ if (strcmp(tmp->name, rng->name) == 0)
+ goto out_unlock;
+ }
+
+ must_register_misc = (current_rng == NULL);
+ old_rng = current_rng;
+ if (!old_rng) {
+ err = hwrng_init(rng);
+ if (err)
+ goto out_unlock;
+ current_rng = rng;
+ }
+ err = 0;
+ if (must_register_misc) {
+ err = register_miscdev();
+ if (err) {
+ if (!old_rng) {
+ hwrng_cleanup(rng);
+ current_rng = NULL;
+ }
+ goto out_unlock;
+ }
+ }
+ INIT_LIST_HEAD(&rng->list);
+ list_add_tail(&rng->list, &rng_list);
+out_unlock:
+ mutex_unlock(&rng_mutex);
+out:
+ return err;
+}
+EXPORT_SYMBOL_GPL(hwrng_register);
+
+void hwrng_unregister(struct hwrng *rng)
+{
+ int err;
+
+ mutex_lock(&rng_mutex);
+
+ list_del(&rng->list);
+ if (current_rng == rng) {
+ hwrng_cleanup(rng);
+ if (list_empty(&rng_list)) {
+ current_rng = NULL;
+ } else {
+ current_rng = list_entry(rng_list.prev, struct hwrng, list);
+ err = hwrng_init(current_rng);
+ if (err)
+ current_rng = NULL;
+ }
+ }
+ if (list_empty(&rng_list))
+ unregister_miscdev();
+
+ mutex_unlock(&rng_mutex);
+}
+EXPORT_SYMBOL_GPL(hwrng_unregister);
+
+
+MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
+MODULE_LICENSE("GPL");
git://git.onelab.eu / linux-2.6.git / blobdiff