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![Oliver Neukum](/assets/img/avatar_default.png)
In case of a timeout or if a signal aborts a read communication with the device needs to be ended lest we overwrite an active URB the next time we do IO to the device, as the URB may still be active. Signed-off-by: Oliver Neukum <oneukum@suse.de> Cc: stable <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20191107142856.16774-1-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
584 lines
13 KiB
C
584 lines
13 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* chaoskey - driver for ChaosKey device from Altus Metrum.
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*
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* This device provides true random numbers using a noise source based
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* on a reverse-biased p-n junction in avalanche breakdown. More
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* details can be found at http://chaoskey.org
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*
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* The driver connects to the kernel hardware RNG interface to provide
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* entropy for /dev/random and other kernel activities. It also offers
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* a separate /dev/ entry to allow for direct access to the random
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* bit stream.
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*
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* Copyright © 2015 Keith Packard <keithp@keithp.com>
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*/
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <linux/usb.h>
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#include <linux/wait.h>
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#include <linux/hw_random.h>
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#include <linux/mutex.h>
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#include <linux/uaccess.h>
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static struct usb_driver chaoskey_driver;
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static struct usb_class_driver chaoskey_class;
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static int chaoskey_rng_read(struct hwrng *rng, void *data,
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size_t max, bool wait);
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#define usb_dbg(usb_if, format, arg...) \
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dev_dbg(&(usb_if)->dev, format, ## arg)
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#define usb_err(usb_if, format, arg...) \
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dev_err(&(usb_if)->dev, format, ## arg)
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/* Version Information */
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#define DRIVER_AUTHOR "Keith Packard, keithp@keithp.com"
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#define DRIVER_DESC "Altus Metrum ChaosKey driver"
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#define DRIVER_SHORT "chaoskey"
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MODULE_AUTHOR(DRIVER_AUTHOR);
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MODULE_DESCRIPTION(DRIVER_DESC);
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MODULE_LICENSE("GPL");
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#define CHAOSKEY_VENDOR_ID 0x1d50 /* OpenMoko */
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#define CHAOSKEY_PRODUCT_ID 0x60c6 /* ChaosKey */
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#define ALEA_VENDOR_ID 0x12d8 /* Araneus */
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#define ALEA_PRODUCT_ID 0x0001 /* Alea I */
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#define CHAOSKEY_BUF_LEN 64 /* max size of USB full speed packet */
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#define NAK_TIMEOUT (HZ) /* normal stall/wait timeout */
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#define ALEA_FIRST_TIMEOUT (HZ*3) /* first stall/wait timeout for Alea */
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#ifdef CONFIG_USB_DYNAMIC_MINORS
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#define USB_CHAOSKEY_MINOR_BASE 0
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#else
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/* IOWARRIOR_MINOR_BASE + 16, not official yet */
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#define USB_CHAOSKEY_MINOR_BASE 224
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#endif
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static const struct usb_device_id chaoskey_table[] = {
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{ USB_DEVICE(CHAOSKEY_VENDOR_ID, CHAOSKEY_PRODUCT_ID) },
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{ USB_DEVICE(ALEA_VENDOR_ID, ALEA_PRODUCT_ID) },
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{ },
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};
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MODULE_DEVICE_TABLE(usb, chaoskey_table);
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static void chaos_read_callback(struct urb *urb);
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/* Driver-local specific stuff */
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struct chaoskey {
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struct usb_interface *interface;
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char in_ep;
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struct mutex lock;
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struct mutex rng_lock;
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int open; /* open count */
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bool present; /* device not disconnected */
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bool reading; /* ongoing IO */
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bool reads_started; /* track first read for Alea */
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int size; /* size of buf */
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int valid; /* bytes of buf read */
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int used; /* bytes of buf consumed */
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char *name; /* product + serial */
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struct hwrng hwrng; /* Embedded struct for hwrng */
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int hwrng_registered; /* registered with hwrng API */
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wait_queue_head_t wait_q; /* for timeouts */
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struct urb *urb; /* for performing IO */
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char *buf;
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};
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static void chaoskey_free(struct chaoskey *dev)
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{
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if (dev) {
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usb_dbg(dev->interface, "free");
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usb_free_urb(dev->urb);
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kfree(dev->name);
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kfree(dev->buf);
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usb_put_intf(dev->interface);
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kfree(dev);
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}
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}
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static int chaoskey_probe(struct usb_interface *interface,
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const struct usb_device_id *id)
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{
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struct usb_device *udev = interface_to_usbdev(interface);
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struct usb_host_interface *altsetting = interface->cur_altsetting;
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struct usb_endpoint_descriptor *epd;
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int in_ep;
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struct chaoskey *dev;
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int result = -ENOMEM;
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int size;
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int res;
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usb_dbg(interface, "probe %s-%s", udev->product, udev->serial);
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/* Find the first bulk IN endpoint and its packet size */
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res = usb_find_bulk_in_endpoint(altsetting, &epd);
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if (res) {
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usb_dbg(interface, "no IN endpoint found");
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return res;
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}
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in_ep = usb_endpoint_num(epd);
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size = usb_endpoint_maxp(epd);
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/* Validate endpoint and size */
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if (size <= 0) {
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usb_dbg(interface, "invalid size (%d)", size);
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return -ENODEV;
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}
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if (size > CHAOSKEY_BUF_LEN) {
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usb_dbg(interface, "size reduced from %d to %d\n",
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size, CHAOSKEY_BUF_LEN);
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size = CHAOSKEY_BUF_LEN;
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}
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/* Looks good, allocate and initialize */
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dev = kzalloc(sizeof(struct chaoskey), GFP_KERNEL);
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if (dev == NULL)
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goto out;
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dev->interface = usb_get_intf(interface);
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dev->buf = kmalloc(size, GFP_KERNEL);
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if (dev->buf == NULL)
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goto out;
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dev->urb = usb_alloc_urb(0, GFP_KERNEL);
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if (!dev->urb)
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goto out;
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usb_fill_bulk_urb(dev->urb,
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udev,
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usb_rcvbulkpipe(udev, in_ep),
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dev->buf,
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size,
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chaos_read_callback,
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dev);
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/* Construct a name using the product and serial values. Each
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* device needs a unique name for the hwrng code
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*/
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if (udev->product && udev->serial) {
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dev->name = kasprintf(GFP_KERNEL, "%s-%s", udev->product,
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udev->serial);
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if (dev->name == NULL)
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goto out;
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}
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dev->in_ep = in_ep;
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if (le16_to_cpu(udev->descriptor.idVendor) != ALEA_VENDOR_ID)
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dev->reads_started = true;
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dev->size = size;
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dev->present = true;
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init_waitqueue_head(&dev->wait_q);
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mutex_init(&dev->lock);
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mutex_init(&dev->rng_lock);
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usb_set_intfdata(interface, dev);
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result = usb_register_dev(interface, &chaoskey_class);
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if (result) {
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usb_err(interface, "Unable to allocate minor number.");
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goto out;
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}
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dev->hwrng.name = dev->name ? dev->name : chaoskey_driver.name;
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dev->hwrng.read = chaoskey_rng_read;
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dev->hwrng.quality = 1024;
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dev->hwrng_registered = (hwrng_register(&dev->hwrng) == 0);
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if (!dev->hwrng_registered)
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usb_err(interface, "Unable to register with hwrng");
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usb_enable_autosuspend(udev);
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usb_dbg(interface, "chaoskey probe success, size %d", dev->size);
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return 0;
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out:
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usb_set_intfdata(interface, NULL);
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chaoskey_free(dev);
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return result;
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}
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static void chaoskey_disconnect(struct usb_interface *interface)
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{
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struct chaoskey *dev;
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usb_dbg(interface, "disconnect");
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dev = usb_get_intfdata(interface);
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if (!dev) {
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usb_dbg(interface, "disconnect failed - no dev");
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return;
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}
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if (dev->hwrng_registered)
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hwrng_unregister(&dev->hwrng);
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usb_deregister_dev(interface, &chaoskey_class);
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usb_set_intfdata(interface, NULL);
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mutex_lock(&dev->lock);
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dev->present = false;
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usb_poison_urb(dev->urb);
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if (!dev->open) {
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mutex_unlock(&dev->lock);
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chaoskey_free(dev);
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} else
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mutex_unlock(&dev->lock);
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usb_dbg(interface, "disconnect done");
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}
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static int chaoskey_open(struct inode *inode, struct file *file)
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{
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struct chaoskey *dev;
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struct usb_interface *interface;
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/* get the interface from minor number and driver information */
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interface = usb_find_interface(&chaoskey_driver, iminor(inode));
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if (!interface)
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return -ENODEV;
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usb_dbg(interface, "open");
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dev = usb_get_intfdata(interface);
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if (!dev) {
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usb_dbg(interface, "open (dev)");
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return -ENODEV;
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}
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file->private_data = dev;
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mutex_lock(&dev->lock);
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++dev->open;
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mutex_unlock(&dev->lock);
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usb_dbg(interface, "open success");
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return 0;
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}
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static int chaoskey_release(struct inode *inode, struct file *file)
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{
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struct chaoskey *dev = file->private_data;
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struct usb_interface *interface;
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if (dev == NULL)
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return -ENODEV;
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interface = dev->interface;
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usb_dbg(interface, "release");
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mutex_lock(&dev->lock);
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usb_dbg(interface, "open count at release is %d", dev->open);
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if (dev->open <= 0) {
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usb_dbg(interface, "invalid open count (%d)", dev->open);
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mutex_unlock(&dev->lock);
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return -ENODEV;
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}
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--dev->open;
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if (!dev->present) {
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if (dev->open == 0) {
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mutex_unlock(&dev->lock);
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chaoskey_free(dev);
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} else
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mutex_unlock(&dev->lock);
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} else
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mutex_unlock(&dev->lock);
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usb_dbg(interface, "release success");
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return 0;
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}
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static void chaos_read_callback(struct urb *urb)
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{
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struct chaoskey *dev = urb->context;
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int status = urb->status;
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usb_dbg(dev->interface, "callback status (%d)", status);
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if (status == 0)
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dev->valid = urb->actual_length;
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else
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dev->valid = 0;
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dev->used = 0;
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/* must be seen first before validity is announced */
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smp_wmb();
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dev->reading = false;
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wake_up(&dev->wait_q);
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}
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/* Fill the buffer. Called with dev->lock held
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*/
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static int _chaoskey_fill(struct chaoskey *dev)
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{
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DEFINE_WAIT(wait);
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int result;
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bool started;
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usb_dbg(dev->interface, "fill");
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/* Return immediately if someone called before the buffer was
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* empty */
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if (dev->valid != dev->used) {
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usb_dbg(dev->interface, "not empty yet (valid %d used %d)",
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dev->valid, dev->used);
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return 0;
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}
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/* Bail if the device has been removed */
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if (!dev->present) {
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usb_dbg(dev->interface, "device not present");
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return -ENODEV;
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}
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/* Make sure the device is awake */
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result = usb_autopm_get_interface(dev->interface);
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if (result) {
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usb_dbg(dev->interface, "wakeup failed (result %d)", result);
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return result;
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}
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dev->reading = true;
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result = usb_submit_urb(dev->urb, GFP_KERNEL);
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if (result < 0) {
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result = usb_translate_errors(result);
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dev->reading = false;
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goto out;
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}
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/* The first read on the Alea takes a little under 2 seconds.
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* Reads after the first read take only a few microseconds
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* though. Presumably the entropy-generating circuit needs
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* time to ramp up. So, we wait longer on the first read.
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*/
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started = dev->reads_started;
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dev->reads_started = true;
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result = wait_event_interruptible_timeout(
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dev->wait_q,
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!dev->reading,
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(started ? NAK_TIMEOUT : ALEA_FIRST_TIMEOUT) );
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if (result < 0) {
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usb_kill_urb(dev->urb);
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goto out;
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}
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if (result == 0) {
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result = -ETIMEDOUT;
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usb_kill_urb(dev->urb);
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} else {
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result = dev->valid;
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}
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out:
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/* Let the device go back to sleep eventually */
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usb_autopm_put_interface(dev->interface);
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usb_dbg(dev->interface, "read %d bytes", dev->valid);
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return result;
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}
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static ssize_t chaoskey_read(struct file *file,
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char __user *buffer,
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size_t count,
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loff_t *ppos)
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{
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struct chaoskey *dev;
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ssize_t read_count = 0;
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int this_time;
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int result = 0;
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unsigned long remain;
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dev = file->private_data;
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if (dev == NULL || !dev->present)
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return -ENODEV;
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usb_dbg(dev->interface, "read %zu", count);
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while (count > 0) {
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|
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/* Grab the rng_lock briefly to ensure that the hwrng interface
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* gets priority over other user access
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*/
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result = mutex_lock_interruptible(&dev->rng_lock);
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if (result)
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goto bail;
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mutex_unlock(&dev->rng_lock);
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result = mutex_lock_interruptible(&dev->lock);
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if (result)
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goto bail;
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if (dev->valid == dev->used) {
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result = _chaoskey_fill(dev);
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if (result < 0) {
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mutex_unlock(&dev->lock);
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goto bail;
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}
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}
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this_time = dev->valid - dev->used;
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if (this_time > count)
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this_time = count;
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remain = copy_to_user(buffer, dev->buf + dev->used, this_time);
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if (remain) {
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result = -EFAULT;
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|
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/* Consume the bytes that were copied so we don't leak
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* data to user space
|
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*/
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dev->used += this_time - remain;
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mutex_unlock(&dev->lock);
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goto bail;
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}
|
|
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count -= this_time;
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read_count += this_time;
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|
buffer += this_time;
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dev->used += this_time;
|
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mutex_unlock(&dev->lock);
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}
|
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bail:
|
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if (read_count) {
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usb_dbg(dev->interface, "read %zu bytes", read_count);
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return read_count;
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}
|
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usb_dbg(dev->interface, "empty read, result %d", result);
|
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if (result == -ETIMEDOUT)
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result = -EAGAIN;
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return result;
|
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}
|
|
|
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static int chaoskey_rng_read(struct hwrng *rng, void *data,
|
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size_t max, bool wait)
|
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{
|
|
struct chaoskey *dev = container_of(rng, struct chaoskey, hwrng);
|
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int this_time;
|
|
|
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usb_dbg(dev->interface, "rng_read max %zu wait %d", max, wait);
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|
|
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if (!dev->present) {
|
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usb_dbg(dev->interface, "device not present");
|
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return 0;
|
|
}
|
|
|
|
/* Hold the rng_lock until we acquire the device lock so that
|
|
* this operation gets priority over other user access to the
|
|
* device
|
|
*/
|
|
mutex_lock(&dev->rng_lock);
|
|
|
|
mutex_lock(&dev->lock);
|
|
|
|
mutex_unlock(&dev->rng_lock);
|
|
|
|
/* Try to fill the buffer if empty. It doesn't actually matter
|
|
* if _chaoskey_fill works; we'll just return zero bytes as
|
|
* the buffer will still be empty
|
|
*/
|
|
if (dev->valid == dev->used)
|
|
(void) _chaoskey_fill(dev);
|
|
|
|
this_time = dev->valid - dev->used;
|
|
if (this_time > max)
|
|
this_time = max;
|
|
|
|
memcpy(data, dev->buf + dev->used, this_time);
|
|
|
|
dev->used += this_time;
|
|
|
|
mutex_unlock(&dev->lock);
|
|
|
|
usb_dbg(dev->interface, "rng_read this_time %d\n", this_time);
|
|
return this_time;
|
|
}
|
|
|
|
#ifdef CONFIG_PM
|
|
static int chaoskey_suspend(struct usb_interface *interface,
|
|
pm_message_t message)
|
|
{
|
|
usb_dbg(interface, "suspend");
|
|
return 0;
|
|
}
|
|
|
|
static int chaoskey_resume(struct usb_interface *interface)
|
|
{
|
|
struct chaoskey *dev;
|
|
struct usb_device *udev = interface_to_usbdev(interface);
|
|
|
|
usb_dbg(interface, "resume");
|
|
dev = usb_get_intfdata(interface);
|
|
|
|
/*
|
|
* We may have lost power.
|
|
* In that case the device that needs a long time
|
|
* for the first requests needs an extended timeout
|
|
* again
|
|
*/
|
|
if (le16_to_cpu(udev->descriptor.idVendor) == ALEA_VENDOR_ID)
|
|
dev->reads_started = false;
|
|
|
|
return 0;
|
|
}
|
|
#else
|
|
#define chaoskey_suspend NULL
|
|
#define chaoskey_resume NULL
|
|
#endif
|
|
|
|
/* file operation pointers */
|
|
static const struct file_operations chaoskey_fops = {
|
|
.owner = THIS_MODULE,
|
|
.read = chaoskey_read,
|
|
.open = chaoskey_open,
|
|
.release = chaoskey_release,
|
|
.llseek = default_llseek,
|
|
};
|
|
|
|
/* class driver information */
|
|
static struct usb_class_driver chaoskey_class = {
|
|
.name = "chaoskey%d",
|
|
.fops = &chaoskey_fops,
|
|
.minor_base = USB_CHAOSKEY_MINOR_BASE,
|
|
};
|
|
|
|
/* usb specific object needed to register this driver with the usb subsystem */
|
|
static struct usb_driver chaoskey_driver = {
|
|
.name = DRIVER_SHORT,
|
|
.probe = chaoskey_probe,
|
|
.disconnect = chaoskey_disconnect,
|
|
.suspend = chaoskey_suspend,
|
|
.resume = chaoskey_resume,
|
|
.reset_resume = chaoskey_resume,
|
|
.id_table = chaoskey_table,
|
|
.supports_autosuspend = 1,
|
|
};
|
|
|
|
module_usb_driver(chaoskey_driver);
|
|
|