Adds support for the Araneus Alea I USB hardware Random Number
Generator. This RNG creates entropy at a high rate, about 100kb/s.
Signed-off-by: Bob Ham <bob.ham@xxxxxxxxxxxxx>
---
Just a note about the name of the module, I haven't append "-rng" to
the name, like every other module in hw_random, because those modules
contain drivers for the RNG part of some more complex device. By
contrast, the Alea is solely an RNG so adding "-rng" to the name seems
redundant.
drivers/char/hw_random/Kconfig | 13 ++
drivers/char/hw_random/Makefile | 1 +
drivers/char/hw_random/alea.c | 370 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 384 insertions(+)
create mode 100644 drivers/char/hw_random/alea.c
diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
index ac51149..b3f5a89 100644
--- a/drivers/char/hw_random/Kconfig
+++ b/drivers/char/hw_random/Kconfig
@@ -396,6 +396,19 @@ config HW_RANDOM_PIC32
If unsure, say Y.
+config HW_RANDOM_ALEA
+ tristate "Araneus Alea I USB Random Number Generator support"
+ depends on HW_RANDOM && USB
+ default n
+ ---help---
+ This driver provides kernel-side support for the Araneus
+ Alea I USB hardware Random Number Generator.
+
+ To compile this driver as a module, choose M here. the
+ module will be called alea.
+
+ If unsure, say N.
+
endif # HW_RANDOM
config UML_RANDOM
diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
index 63022b4..3709906 100644
--- a/drivers/char/hw_random/Makefile
+++ b/drivers/char/hw_random/Makefile
@@ -34,3 +34,4 @@ obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
obj-$(CONFIG_HW_RANDOM_STM32) += stm32-rng.o
obj-$(CONFIG_HW_RANDOM_PIC32) += pic32-rng.o
+obj-$(CONFIG_HW_RANDOM_ALEA) += alea.o
diff --git a/drivers/char/hw_random/alea.c b/drivers/char/hw_random/alea.c
new file mode 100644
index 0000000..50909da
--- /dev/null
+++ b/drivers/char/hw_random/alea.c
@@ -0,0 +1,370 @@
+/*
+ * Copyright (C) 2016 Collabora Ltd
+ * Written by Bob Ham <bob.ham@xxxxxxxxxxxxx>
+ *
+ * An HWRNG driver to pull data from an Araneus Alea I
+ *
+ * derived from:
+ *
+ * USB Skeleton driver - 2.2
+ *
+ * Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@xxxxxxxxx)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2.
+ *
+ * This driver is based on the 2.6.3 version of drivers/usb/usb-skeleton.c
+ * but has been rewritten to be easier to read and use.
+ *
+ */
+
+/*
+ * The Alea I is a really simple device. There is one bulk read
+ * endpoint. It spits out data in 64-byte chunks. Each chunk
+ * contains entropy. Simple.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/kref.h>
+#include <linux/uaccess.h>
+#include <linux/usb.h>
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
+#include <linux/hw_random.h>
+
+
+#define MODULE_NAME "alea"
+
+#define ARANEUS_VENDOR_ID 0x12d8
+#define ARANEUS_ALEA_I_PRODUCT_ID 0x0001
+
+/* table of devices that work with this driver */
+static const struct usb_device_id alea_table[] = {
+ { USB_DEVICE(ARANEUS_VENDOR_ID, ARANEUS_ALEA_I_PRODUCT_ID) },
+ { } /* Terminating entry */
+};
+
+MODULE_DEVICE_TABLE (usb, alea_table);
+
+
+/* Structure to hold all of our device specific stuff */
+struct alea {
+ struct usb_device *udev; /* the usb device for this device */
+ struct usb_interface *interface; /* the interface for this device */
+ struct urb *bulk_in_urb; /* the urb to read data with */
+ unsigned char *bulk_in_buffer; /* the buffer to receive data */
+ size_t bulk_in_size; /* the size of the receive buffer */
+ size_t bulk_in_filled; /* number of bytes in the buffer */
+ __u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */
+ int errors; /* the last request tanked */
+ bool ongoing_read; /* a read is going on */
+ spinlock_t err_lock; /* lock for errors */
+ struct kref kref;
+ struct mutex io_mutex; /* synchronize I/O with disconnect */
+ wait_queue_head_t bulk_in_wait; /* to wait for an ongoing read */
+ char *rng_name; /* name for the hwrng subsystem */
+ struct hwrng rng; /* the hwrng info */
+};
+#define kref_to_alea(d) container_of(d, struct alea, kref)
+#define rng_to_alea(d) container_of(d, struct alea, rng)
+
+static struct usb_driver alea_driver;
+
+static void alea_delete(struct kref *kref)
+{
+ struct alea *dev = kref_to_alea(kref);
+
+ kfree(dev->rng_name);
+ usb_free_urb(dev->bulk_in_urb);
+ usb_put_dev(dev->udev);
+ kfree(dev->bulk_in_buffer);
+ kfree(dev);
+}
+
+static void alea_read_callback(struct urb *urb)
+{
+ struct alea *dev = urb->context;
+
+ spin_lock(&dev->err_lock);
+ /* sync/async unlink faults aren't errors */
+ if (urb->status) {
+ if (!(urb->status == -ENOENT ||
+ urb->status == -ECONNRESET ||
+ urb->status == -ESHUTDOWN))
+ dev_err(&dev->interface->dev,
+ "%s - nonzero read bulk status received: %d\n",
+ __func__, urb->status);
+
+ dev->errors = urb->status;
+ } else {
+ dev->bulk_in_filled = urb->actual_length;
+ }
+ dev->ongoing_read = 0;
+ spin_unlock(&dev->err_lock);
+
+ wake_up_interruptible(&dev->bulk_in_wait);
+}
+
+static int alea_request_read(struct alea *dev)
+{
+ int rv;
+
+ /* prepare a read */
+ usb_fill_bulk_urb(dev->bulk_in_urb,
+ dev->udev,
+ usb_rcvbulkpipe(dev->udev,
+ dev->bulk_in_endpointAddr),
+ dev->bulk_in_buffer,
+ dev->bulk_in_size,
+ alea_read_callback,
+ dev);
+ /* tell everybody to leave the URB alone */
+ spin_lock_irq(&dev->err_lock);
+ dev->ongoing_read = 1;
+ spin_unlock_irq(&dev->err_lock);
+
+ /* submit bulk in urb, which means no data to deliver */
+ dev->bulk_in_filled = 0;
+
+ /* do it */
+ rv = usb_submit_urb(dev->bulk_in_urb, GFP_KERNEL);
+ if (rv < 0) {
+ dev_err(&dev->interface->dev,
+ "%s - failed submitting read urb, error %d\n",
+ __func__, rv);
+ rv = (rv == -ENOMEM) ? rv : -EIO;
+ spin_lock_irq(&dev->err_lock);
+ dev->ongoing_read = 0;
+ spin_unlock_irq(&dev->err_lock);
+ }
+
+ return rv;
+}
+
+static int alea_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
+{
+ struct alea *dev;
+ int rv;
+ bool ongoing_io;
+
+ dev = rng_to_alea(rng);
+
+ /* if we cannot read at all */
+ if (!dev->bulk_in_urb)
+ return 0;
+
+ /* no concurrent readers */
+ rv = mutex_lock_interruptible(&dev->io_mutex);
+ if (rv < 0)
+ return rv;
+
+ if (!dev->interface) { /* disconnect() was called */
+ rv = -ENODEV;
+ goto exit;
+ }
+
+ /* if IO is under way, we must not touch things */
+retry:
+ spin_lock_irq(&dev->err_lock);
+ ongoing_io = dev->ongoing_read;
+ spin_unlock_irq(&dev->err_lock);
+
+ if (ongoing_io) {
+ if (!wait) {
+ rv = 0;
+ goto exit;
+ }
+
+ /*
+ * IO may take forever
+ * hence wait in an interruptible state
+ */
+ rv = wait_event_interruptible(dev->bulk_in_wait, (!dev->ongoing_read));
+ if (rv < 0)
+ goto exit;
+ }
+
+ /* errors must be reported */
+ rv = dev->errors;
+ if (rv < 0) {
+ /* any error is reported once */
+ dev->errors = 0;
+ /* to preserve notifications about reset */
+ rv = (rv == -EPIPE) ? rv : -EIO;
+ /* report it */
+ goto exit;
+ }
+
+ if (dev->bulk_in_filled) {
+ /* we have data to return */
+ rv = min(dev->bulk_in_filled, max);
+ dev->bulk_in_filled -= rv;
+ memcpy(data, dev->bulk_in_buffer + dev->bulk_in_filled, rv);
+ } else {
+ rv = 0;
+ }
+
+ if (!dev->bulk_in_filled) {
+ /* we need more data */
+ int err;
+
+ err = alea_request_read(dev);
+ if (err < 0) {
+ rv = err;
+ goto exit;
+ }
+
+ /* possibly wait if we haven't copied any data yet */
+ if (!rv && wait)
+ goto retry;
+ }
+exit:
+ mutex_unlock(&dev->io_mutex);
+ return rv;
+}
+
+static int alea_probe(struct usb_interface *interface,
+ const struct usb_device_id *id)
+{
+ struct alea *dev;
+ struct usb_host_interface *iface_desc;
+ struct usb_endpoint_descriptor *endpoint;
+ int i;
+ int retval = -ENOMEM;
+ char temp_name[1];
+ int name_size;
+
+ /* allocate memory for our device state and initialize it */
+ dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+ if (!dev) {
+ dev_err(&interface->dev, "Out of memory\n");
+ goto error;
+ }
+ kref_init(&dev->kref);
+ mutex_init(&dev->io_mutex);
+ spin_lock_init(&dev->err_lock);
+ init_waitqueue_head(&dev->bulk_in_wait);
+
+ dev->udev = usb_get_dev(interface_to_usbdev(interface));
+ dev->interface = interface;
+
+ dev->rng.read = alea_rng_read;
+
+ /* set up the endpoint information */
+ iface_desc = interface->cur_altsetting;
+ for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
+ endpoint = &iface_desc->endpoint[i].desc;
+
+ if (!usb_endpoint_is_bulk_in(endpoint))
+ continue;
+
+ /* we found our bulk in endpoint */
+ dev->bulk_in_size = usb_endpoint_maxp(endpoint);
+ dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
+ break;
+ }
+ if (!dev->bulk_in_endpointAddr) {
+ dev_err(&interface->dev,
+ "Could not find endpoint\n");
+ goto error;
+ }
+
+ /* allocate objects */
+ dev->bulk_in_buffer = kmalloc(dev->bulk_in_size, GFP_KERNEL);
+ if (!dev->bulk_in_buffer) {
+ dev_err(&interface->dev,
+ "Could not allocate bulk_in_buffer\n");
+ goto error;
+ }
+ dev->bulk_in_urb = usb_alloc_urb(0, GFP_KERNEL);
+ if (!dev->bulk_in_urb) {
+ dev_err(&interface->dev,
+ "Could not allocate bulk_in_urb\n");
+ goto error;
+ }
+
+ /* set name for hwrng */
+ name_size = 1 + snprintf(temp_name, sizeof(temp_name),
+ "alea-%s", dev_name(&interface->dev));
+ dev->rng_name = kmalloc(name_size, GFP_KERNEL);
+ if (!dev->rng_name) {
+ dev_err(&interface->dev,
+ "Could not allocate rng_name\n");
+ goto error;
+ }
+ snprintf(dev->rng_name, name_size,
+ "alea-%s", dev_name(&interface->dev));
+ dev->rng.name = &dev->rng_name[0];
+
+ /* save our data pointer in this interface device */
+ usb_set_intfdata(interface, dev);
+
+ /* kick off the first read */
+ retval = alea_request_read(dev);
+ if (retval) {
+ dev_err(&interface->dev,
+ "Could not start first USB read\n");
+ goto error_intf;
+ }
+
+ /* register with hwrng subsystem */
+ retval = devm_hwrng_register(&dev->udev->dev, &dev->rng);
+ if (retval) {
+ dev_err(&interface->dev,
+ "Not able to register RNG for this device.\n");
+ goto error_intf;
+ }
+
+ /* let the user know what node this device is now attached to */
+ dev_info(&interface->dev,
+ "Araneus Alea I device now attached to RNG %s",
+ dev->rng_name);
+ return 0;
+
+error_intf:
+ usb_set_intfdata(interface, NULL);
+error:
+ if (dev)
+ /* this frees allocated memory */
+ kref_put(&dev->kref, alea_delete);
+ return retval;
+}
+
+static void alea_disconnect(struct usb_interface *interface)
+{
+ struct alea *dev;
+
+ dev = usb_get_intfdata(interface);
+ usb_set_intfdata(interface, NULL);
+
+ /* remove us from the hwrng subsystem */
+ devm_hwrng_unregister(&dev->udev->dev, &dev->rng);
+
+ /* prevent more I/O from starting */
+ mutex_lock(&dev->io_mutex);
+ dev->interface = NULL;
+ mutex_unlock(&dev->io_mutex);
+
+ dev_info(&interface->dev,
+ "Araneus Alea I %s now disconnected",
+ dev->rng_name);
+
+ /* decrement our usage count */
+ kref_put(&dev->kref, alea_delete);
+}
+
+static struct usb_driver alea_driver = {
+ .name = MODULE_NAME,
+ .probe = alea_probe,
+ .disconnect = alea_disconnect,
+ .id_table = alea_table,
+};
+
+module_usb_driver(alea_driver);
+
+MODULE_LICENSE("GPL");
--
2.1.4
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