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Diffstat (limited to 'drivers/char/hw_random/core.c')
-rw-r--r--drivers/char/hw_random/core.c427
1 files changed, 427 insertions, 0 deletions
diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
new file mode 100644
index 00000000000..c4419ea1ab0
--- /dev/null
+++ b/drivers/char/hw_random/core.c
@@ -0,0 +1,427 @@
+/*
+ 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 <m@bues.ch>
+ 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/sched.h>
+#include <linux/miscdevice.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/random.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 int data_avail;
+static u8 *rng_buffer;
+
+static inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
+ int wait);
+
+static size_t rng_buffer_size(void)
+{
+ return SMP_CACHE_BYTES < 32 ? 32 : SMP_CACHE_BYTES;
+}
+
+static void add_early_randomness(struct hwrng *rng)
+{
+ unsigned char bytes[16];
+ int bytes_read;
+
+ /*
+ * Currently only virtio-rng cannot return data during device
+ * probe, and that's handled in virtio-rng.c itself. If there
+ * are more such devices, this call to rng_get_data can be
+ * made conditional here instead of doing it per-device.
+ */
+ bytes_read = rng_get_data(rng, bytes, sizeof(bytes), 1);
+ if (bytes_read > 0)
+ add_device_randomness(bytes, bytes_read);
+}
+
+static inline int hwrng_init(struct hwrng *rng)
+{
+ if (rng->init) {
+ int ret;
+
+ ret = rng->init(rng);
+ if (ret)
+ return ret;
+ }
+ add_early_randomness(rng);
+ return 0;
+}
+
+static inline void hwrng_cleanup(struct hwrng *rng)
+{
+ if (rng && rng->cleanup)
+ rng->cleanup(rng);
+}
+
+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 inline int rng_get_data(struct hwrng *rng, u8 *buffer, size_t size,
+ int wait) {
+ int present;
+
+ if (rng->read)
+ return rng->read(rng, (void *)buffer, size, wait);
+
+ if (rng->data_present)
+ present = rng->data_present(rng, wait);
+ else
+ present = 1;
+
+ if (present)
+ return rng->data_read(rng, (u32 *)buffer);
+
+ return 0;
+}
+
+static ssize_t rng_dev_read(struct file *filp, char __user *buf,
+ size_t size, loff_t *offp)
+{
+ ssize_t ret = 0;
+ int err = 0;
+ int bytes_read, len;
+
+ while (size) {
+ if (mutex_lock_interruptible(&rng_mutex)) {
+ err = -ERESTARTSYS;
+ goto out;
+ }
+
+ if (!current_rng) {
+ err = -ENODEV;
+ goto out_unlock;
+ }
+
+ if (!data_avail) {
+ bytes_read = rng_get_data(current_rng, rng_buffer,
+ rng_buffer_size(),
+ !(filp->f_flags & O_NONBLOCK));
+ if (bytes_read < 0) {
+ err = bytes_read;
+ goto out_unlock;
+ }
+ data_avail = bytes_read;
+ }
+
+ if (!data_avail) {
+ if (filp->f_flags & O_NONBLOCK) {
+ err = -EAGAIN;
+ goto out_unlock;
+ }
+ } else {
+ len = data_avail;
+ if (len > size)
+ len = size;
+
+ data_avail -= len;
+
+ if (copy_to_user(buf + ret, rng_buffer + data_avail,
+ len)) {
+ err = -EFAULT;
+ goto out_unlock;
+ }
+
+ size -= len;
+ ret += len;
+ }
+
+ mutex_unlock(&rng_mutex);
+
+ if (need_resched())
+ schedule_timeout_interruptible(1);
+
+ if (signal_pending(current)) {
+ err = -ERESTARTSYS;
+ goto out;
+ }
+ }
+out:
+ return ret ? : err;
+out_unlock:
+ mutex_unlock(&rng_mutex);
+ goto out;
+}
+
+
+static const struct file_operations rng_chrdev_ops = {
+ .owner = THIS_MODULE,
+ .open = rng_dev_open,
+ .read = rng_dev_read,
+ .llseek = noop_llseek,
+};
+
+static struct miscdevice rng_miscdev = {
+ .minor = RNG_MISCDEV_MINOR,
+ .name = RNG_MODULE_NAME,
+ .nodename = "hwrng",
+ .fops = &rng_chrdev_ops,
+};
+
+
+static ssize_t hwrng_attr_current_store(struct device *dev,
+ struct device_attribute *attr,
+ 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 device *dev,
+ struct device_attribute *attr,
+ 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 device *dev,
+ struct device_attribute *attr,
+ 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 DEVICE_ATTR(rng_current, S_IRUGO | S_IWUSR,
+ hwrng_attr_current_show,
+ hwrng_attr_current_store);
+static DEVICE_ATTR(rng_available, S_IRUGO,
+ hwrng_attr_available_show,
+ NULL);
+
+
+static void unregister_miscdev(void)
+{
+ device_remove_file(rng_miscdev.this_device, &dev_attr_rng_available);
+ device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
+ misc_deregister(&rng_miscdev);
+}
+
+static int register_miscdev(void)
+{
+ int err;
+
+ err = misc_register(&rng_miscdev);
+ if (err)
+ goto out;
+ err = device_create_file(rng_miscdev.this_device,
+ &dev_attr_rng_current);
+ if (err)
+ goto err_misc_dereg;
+ err = device_create_file(rng_miscdev.this_device,
+ &dev_attr_rng_available);
+ if (err)
+ goto err_remove_current;
+out:
+ return err;
+
+err_remove_current:
+ device_remove_file(rng_miscdev.this_device, &dev_attr_rng_current);
+err_misc_dereg:
+ misc_deregister(&rng_miscdev);
+ goto out;
+}
+
+int hwrng_register(struct hwrng *rng)
+{
+ int err = -EINVAL;
+ struct hwrng *old_rng, *tmp;
+
+ if (rng->name == NULL ||
+ (rng->data_read == NULL && rng->read == NULL))
+ goto out;
+
+ mutex_lock(&rng_mutex);
+
+ /* kmalloc makes this safe for virt_to_page() in virtio_rng.c */
+ err = -ENOMEM;
+ if (!rng_buffer) {
+ rng_buffer = kmalloc(rng_buffer_size(), GFP_KERNEL);
+ if (!rng_buffer)
+ goto out_unlock;
+ }
+
+ /* 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;
+ }
+
+ old_rng = current_rng;
+ if (!old_rng) {
+ err = hwrng_init(rng);
+ if (err)
+ goto out_unlock;
+ current_rng = rng;
+ }
+ err = 0;
+ if (!old_rng) {
+ err = register_miscdev();
+ if (err) {
+ hwrng_cleanup(rng);
+ current_rng = NULL;
+ goto out_unlock;
+ }
+ }
+ INIT_LIST_HEAD(&rng->list);
+ list_add_tail(&rng->list, &rng_list);
+
+ if (old_rng && !rng->init) {
+ /*
+ * Use a new device's input to add some randomness to
+ * the system. If this rng device isn't going to be
+ * used right away, its init function hasn't been
+ * called yet; so only use the randomness from devices
+ * that don't need an init callback.
+ */
+ add_early_randomness(rng);
+ }
+
+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);
+
+static void __exit hwrng_exit(void)
+{
+ mutex_lock(&rng_mutex);
+ BUG_ON(current_rng);
+ kfree(rng_buffer);
+ mutex_unlock(&rng_mutex);
+}
+
+module_exit(hwrng_exit);
+
+MODULE_DESCRIPTION("H/W Random Number Generator (RNG) driver");
+MODULE_LICENSE("GPL");
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