/*      $OpenBSD: urng.c,v 1.11 2024/05/23 03:21:09 jsg Exp $ */

/*
 * Copyright (c) 2017 Jasper Lievisse Adriaanse <jasper@openbsd.org>
 * Copyright (c) 2017 Aaron Bieber <abieber@openbsd.org>
 * Copyright (C) 2015 Sean Levy <attila@stalphonsos.com>
 * Copyright (c) 2007 Marc Balmer <mbalmer@openbsd.org>
 * Copyright (c) 2006 Alexander Yurchenko <grange@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * Universal TRNG driver for a collection of TRNG devices:
 * - ChaosKey TRNG
 *   http://altusmetrum.org/ChaosKey/
 * - Alea II TRNG.  Produces 100kbit/sec of entropy by black magic
 *   http://www.araneus.fi/products/alea2/en/
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/device.h>
#include <sys/timeout.h>

#include <dev/usb/usb.h>
#include <dev/usb/usbdi.h>
#include <dev/usb/usbdevs.h>

#define DEVNAME(_sc) ((_sc)->sc_dev.dv_xname)

#ifdef URNG_DEBUG
#define DPRINTF(x)      printf x
#else
#define DPRINTF(x)
#endif

/*
 * Define URNG_MEASURE_RATE to periodically log rate at which we provide
 * random data to the kernel.
 */
#ifdef URNG_MEASURE_RATE
#define URNG_RATE_SECONDS 30
#endif

struct urng_chip {
        int     bufsiz;
        int     endpoint;
        int     ctl_iface_idx;
        int     msecs;
        int     read_timeout;
};

struct urng_softc {
        struct  device           sc_dev;
        struct  usbd_device     *sc_udev;
        struct  usbd_pipe       *sc_inpipe;
        struct  timeout          sc_timeout;
        struct  usb_task         sc_task;
        struct  usbd_xfer       *sc_xfer;
        struct  urng_chip        sc_chip;
        int                     *sc_buf;
        int                      sc_product;
#ifdef URNG_MEASURE_RATE
        struct  timeval          sc_start;
        struct  timeval          sc_cur;
        int                      sc_counted_bytes;
        u_char                   sc_first_run;
#endif
};

int urng_match(struct device *, void *, void *);
void urng_attach(struct device *, struct device *, void *);
int urng_detach(struct device *, int);
void urng_task(void *);
void urng_timeout(void *);

struct cfdriver urng_cd = {
        NULL, "urng", DV_DULL
};

const struct cfattach urng_ca = {
        sizeof(struct urng_softc), urng_match, urng_attach, urng_detach
};

struct urng_type {
        struct usb_devno        urng_dev;
        struct urng_chip        urng_chip;
};

static const struct urng_type urng_devs[] = {
        { { USB_VENDOR_OPENMOKO2, USB_PRODUCT_OPENMOKO2_CHAOSKEY },
          {64, 5, 0, 100, 5000} },
        { { USB_VENDOR_ARANEUS, USB_PRODUCT_ARANEUS_ALEA },
          {128, 1, 0, 100, 5000} },
};
#define urng_lookup(v, p) ((struct urng_type *)usb_lookup(urng_devs, v, p))

int
urng_match(struct device *parent, void *match, void *aux)
{
        struct usb_attach_arg *uaa = aux;

        if (uaa->iface == NULL)
                return (UMATCH_NONE);

        if (urng_lookup(uaa->vendor, uaa->product) != NULL)
                return (UMATCH_VENDOR_PRODUCT);

        return (UMATCH_NONE);
}

void
urng_attach(struct device *parent, struct device *self, void *aux)
{
        struct urng_softc *sc = (struct urng_softc *)self;
        struct usb_attach_arg *uaa = aux;
        usb_interface_descriptor_t *id;
        usb_endpoint_descriptor_t *ed;
        int ep_ibulk = -1;
        usbd_status error;
        int i, ep_addr;

        sc->sc_udev = uaa->device;
        sc->sc_chip = urng_lookup(uaa->vendor, uaa->product)->urng_chip;
        sc->sc_product = uaa->product;
#ifdef URNG_MEASURE_RATE
        sc->sc_first_run = 1;
#endif

        DPRINTF(("%s: bufsiz: %d, endpoint: %d ctl iface: %d, msecs: %d, read_timeout: %d\n",
                DEVNAME(sc),
                sc->sc_chip.bufsiz,
                sc->sc_chip.endpoint,
                sc->sc_chip.ctl_iface_idx,
                sc->sc_chip.msecs,
                sc->sc_chip.read_timeout));

        /* Find the bulk endpoints. */
        id = usbd_get_interface_descriptor(uaa->iface);
        for (i = 0; i < id->bNumEndpoints; i++) {
                ed = usbd_interface2endpoint_descriptor(uaa->iface, i);
                if (ed == NULL) {
                        printf("%s: failed to get endpoint %d descriptor\n",
                            DEVNAME(sc), i);
                        goto fail;
                }
                if (UE_GET_DIR(ed->bEndpointAddress) == UE_DIR_IN &&
                    UE_GET_XFERTYPE(ed->bmAttributes) == UE_BULK) {
                        ep_addr = UE_GET_ADDR(ed->bEndpointAddress);

                        DPRINTF(("%s: bulk endpoint %d\n",
                            DEVNAME(sc), ep_addr));

                        if (ep_addr == sc->sc_chip.endpoint) {
                                ep_ibulk = ed->bEndpointAddress;
                                break;
                        }
                }
        }

        if (ep_ibulk == -1) {
                printf("%s: missing bulk input endpoint\n", DEVNAME(sc));
                goto fail;
        }

        /* Open the pipes. */
        error = usbd_open_pipe(uaa->iface, ep_ibulk, USBD_EXCLUSIVE_USE,
                    &sc->sc_inpipe);
        if (error) {
                printf("%s: failed to open bulk-in pipe: %s\n",
                                DEVNAME(sc), usbd_errstr(error));
                goto fail;
        }

        /* Allocate the transfer buffers. */
        sc->sc_xfer = usbd_alloc_xfer(sc->sc_udev);
        if (sc->sc_xfer == NULL) {
                printf("%s: could not alloc xfer\n", DEVNAME(sc));
                goto fail;
        }

        sc->sc_buf = usbd_alloc_buffer(sc->sc_xfer, sc->sc_chip.bufsiz);
        if (sc->sc_buf == NULL) {
                printf("%s: could not alloc %d-byte buffer\n", DEVNAME(sc),
                                sc->sc_chip.bufsiz);
                goto fail;
        }

        /* And off we go! */
        usb_init_task(&sc->sc_task, urng_task, sc, USB_TASK_TYPE_GENERIC);
        timeout_set(&sc->sc_timeout, urng_timeout, sc);
        usb_add_task(sc->sc_udev, &sc->sc_task);

        return;

fail:
        usbd_deactivate(sc->sc_udev);
}

int
urng_detach(struct device *self, int flags)
{
        struct urng_softc *sc = (struct urng_softc *)self;

        usb_rem_task(sc->sc_udev, &sc->sc_task);

        if (timeout_initialized(&sc->sc_timeout))
                timeout_del(&sc->sc_timeout);

        if (sc->sc_xfer != NULL) {
                usbd_free_xfer(sc->sc_xfer);
                sc->sc_xfer = NULL;
        }

        if (sc->sc_inpipe != NULL) {
                usbd_close_pipe(sc->sc_inpipe);
                sc->sc_inpipe = NULL;
        }

        return (0);
}


void
urng_task(void *arg)
{
        struct urng_softc *sc = (struct urng_softc *)arg;
        usbd_status error;
        u_int32_t len, i;
#ifdef URNG_MEASURE_RATE
        time_t elapsed;
        int rate;
#endif
        usbd_setup_xfer(sc->sc_xfer, sc->sc_inpipe, NULL, sc->sc_buf,
            sc->sc_chip.bufsiz, USBD_SHORT_XFER_OK | USBD_SYNCHRONOUS,
            sc->sc_chip.read_timeout, NULL);

        error = usbd_transfer(sc->sc_xfer);
        if (error) {
                printf("%s: xfer failed: %s\n", DEVNAME(sc),
                    usbd_errstr(error));
                goto bail;
        }

        usbd_get_xfer_status(sc->sc_xfer, NULL, NULL, &len, NULL);
        if (len < sizeof(int)) {
                printf("%s: xfer too short (%u bytes) - dropping\n",
                    DEVNAME(sc), len);
                goto bail;
        }

#ifdef URNG_MEASURE_RATE
        if (sc->sc_first_run) {
                sc->sc_counted_bytes = 0;
                getmicrotime(&(sc->sc_start));
        }
        sc->sc_counted_bytes += len;
        getmicrotime(&(sc->sc_cur));
        elapsed = sc->sc_cur.tv_sec - sc->sc_start.tv_sec;
        if (elapsed >= URNG_RATE_SECONDS) {
                rate = (8 * sc->sc_counted_bytes) / (elapsed * 1024);
                printf("%s: transfer rate = %d kb/s\n", DEVNAME(sc), rate);

                /* set up for next measurement */
                sc->sc_counted_bytes = 0;
                getmicrotime(&(sc->sc_start));
        }
#endif

        len /= sizeof(int);
        for (i = 0; i < len; i++) {
                enqueue_randomness(sc->sc_buf[i]);
        }
bail:
#ifdef URNG_MEASURE_RATE
        if (sc->sc_first_run) {
                sc->sc_first_run = 0;
        }
#endif

        timeout_add_msec(&sc->sc_timeout, sc->sc_chip.msecs);
}

void
urng_timeout(void *arg)
{
        struct urng_softc *sc = arg;

        usb_add_task(sc->sc_udev, &sc->sc_task);
}