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....@collabora.com>
---

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....@collabora.com>
+ *
+ * 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 (g...@kroah.com)
+ *
+ *     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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