/*      $NetBSD: ualea.c,v 1.19 2022/03/20 13:18:30 riastradh Exp $     */

/*-
 * Copyright (c) 2017 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Taylor R. Campbell.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ualea.c,v 1.19 2022/03/20 13:18:30 riastradh Exp $");

#include <sys/types.h>
#include <sys/atomic.h>
#include <sys/device_if.h>
#include <sys/kmem.h>
#include <sys/module.h>
#include <sys/rndsource.h>

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

struct ualea_softc {
        device_t                sc_dev;
        kmutex_t                sc_lock;
        krndsource_t            sc_rnd;
        uint16_t                sc_maxpktsize;
        struct usbd_pipe        *sc_pipe;
        /*
         * Lock covers:
         * - sc_needed
         * - sc_inflight
         * - usbd_transfer(sc_xfer)
         */
        struct usbd_xfer        *sc_xfer;
        size_t                  sc_needed;
        bool                    sc_attached:1;
        bool                    sc_inflight:1;
};

static int      ualea_match(device_t, cfdata_t, void *);
static void     ualea_attach(device_t, device_t, void *);
static int      ualea_detach(device_t, int);
static void     ualea_get(size_t, void *);
static void     ualea_xfer_done(struct usbd_xfer *, void *, usbd_status);

CFATTACH_DECL_NEW(ualea, sizeof(struct ualea_softc),
    ualea_match, ualea_attach, ualea_detach, NULL);

static const struct usb_devno ualea_devs[] = {
        { USB_VENDOR_ARANEUS,   USB_PRODUCT_ARANEUS_ALEA },
};

static int
ualea_match(device_t parent, cfdata_t match, void *aux)
{
        struct usbif_attach_arg *uiaa = aux;

        if (usb_lookup(ualea_devs, uiaa->uiaa_vendor, uiaa->uiaa_product))
                return UMATCH_VENDOR_PRODUCT;

        return UMATCH_NONE;
}

static void
ualea_attach(device_t parent, device_t self, void *aux)
{
        struct usbif_attach_arg *uiaa = aux;
        struct ualea_softc *sc = device_private(self);
        const usb_endpoint_descriptor_t *ed;
        char *devinfop;
        usbd_status status;

        /* Print the device info.  */
        aprint_naive("\n");
        aprint_normal("\n");
        devinfop = usbd_devinfo_alloc(uiaa->uiaa_device, 0);
        aprint_normal_dev(self, "%s\n", devinfop);
        usbd_devinfo_free(devinfop);

        /* Initialize the softc.  */
        sc->sc_dev = self;
        mutex_init(&sc->sc_lock, MUTEX_DEFAULT, IPL_SOFTSERIAL);

        /* Get endpoint descriptor 0.  Make sure it's bulk-in.  */
        ed = usbd_interface2endpoint_descriptor(uiaa->uiaa_iface, 0);
        if (ed == NULL) {
                aprint_error_dev(sc->sc_dev, "failed to read endpoint 0\n");
                return;
        }
        if (UE_GET_DIR(ed->bEndpointAddress) != UE_DIR_IN ||
            UE_GET_XFERTYPE(ed->bmAttributes) != UE_BULK) {
                aprint_error_dev(sc->sc_dev, "invalid endpoint\n");
                return;
        }

        /* Remember the maximum packet size.  */
        sc->sc_maxpktsize = UGETW(ed->wMaxPacketSize);

        /* Open an exclusive MP-safe pipe for endpoint 0.  */
        status = usbd_open_pipe(uiaa->uiaa_iface, ed->bEndpointAddress,
            USBD_EXCLUSIVE_USE|USBD_MPSAFE, &sc->sc_pipe);
        if (status) {
                aprint_error_dev(sc->sc_dev, "failed to open pipe: %d\n",
                    status);
                return;
        }

        /* Create an xfer of maximum packet size on the pipe.  */
        status = usbd_create_xfer(sc->sc_pipe, sc->sc_maxpktsize,
            0, 0, &sc->sc_xfer);
        if (status) {
                aprint_error_dev(sc->sc_dev, "failed to create xfer: %d\n",
                    status);
                return;
        }

        if (!pmf_device_register(self, NULL, NULL))
                aprint_error_dev(sc->sc_dev, "failed to register power handler"
                    "\n");

        /* Success!  We are ready to run.  */
        sc->sc_attached = true;
        rndsource_setcb(&sc->sc_rnd, ualea_get, sc);
        rnd_attach_source(&sc->sc_rnd, device_xname(self), RND_TYPE_RNG,
            RND_FLAG_COLLECT_VALUE|RND_FLAG_HASCB);
}

static int
ualea_detach(device_t self, int flags)
{
        struct ualea_softc *sc = device_private(self);

        /* Prevent new use of xfer.  */
        if (sc->sc_attached)
                rnd_detach_source(&sc->sc_rnd);

        /* Prevent xfer from rescheduling itself, if still pending.  */
        mutex_enter(&sc->sc_lock);
        sc->sc_needed = 0;
        mutex_exit(&sc->sc_lock);

        /* Cancel pending xfer.  */
        if (sc->sc_pipe)
                usbd_abort_pipe(sc->sc_pipe);
        KASSERT(!sc->sc_inflight);

        /* All users have drained.  Tear it all down.  */
        if (sc->sc_xfer)
                usbd_destroy_xfer(sc->sc_xfer);
        if (sc->sc_pipe)
                usbd_close_pipe(sc->sc_pipe);
        mutex_destroy(&sc->sc_lock);

        return 0;
}

static void
ualea_xfer(struct ualea_softc *sc)
{
        usbd_status status;

        KASSERT(mutex_owned(&sc->sc_lock));
        KASSERT(sc->sc_attached);
        KASSERT(!sc->sc_inflight);

        /* Do nothing if we need nothing.  */
        if (sc->sc_needed == 0)
                return;

        /* Setup the xfer to call ualea_xfer_done with sc.  */
        usbd_setup_xfer(sc->sc_xfer, sc, usbd_get_buffer(sc->sc_xfer),
            sc->sc_maxpktsize, USBD_SHORT_XFER_OK, USBD_NO_TIMEOUT,
            ualea_xfer_done);

        /* Issue xfer or complain if we can't.  */
        status = usbd_transfer(sc->sc_xfer);
        KASSERT(status != USBD_NORMAL_COMPLETION); /* asynchronous xfer */
        if (status != USBD_IN_PROGRESS) {
                device_printf(sc->sc_dev, "failed to issue xfer: %s\n",
                    usbd_errstr(status));
                /* We failed -- let someone else have a go.  */
                return;
        }

        /* Mark xfer in-flight.  */
        sc->sc_inflight = true;
}

static void
ualea_get(size_t nbytes, void *cookie)
{
        struct ualea_softc *sc = cookie;

        mutex_enter(&sc->sc_lock);
        sc->sc_needed = MAX(sc->sc_needed, nbytes);
        if (!sc->sc_inflight)
                ualea_xfer(sc);
        mutex_exit(&sc->sc_lock);
}

static void
ualea_xfer_done(struct usbd_xfer *xfer, void *cookie, usbd_status status)
{
        struct ualea_softc *sc = cookie;
        void *pkt;
        uint32_t pktsize;

        /*
         * If the transfer failed, give up -- forget what we need and
         * don't reschedule ourselves.
         */
        if (status) {
                device_printf(sc->sc_dev, "xfer failed: %s\n",
                    usbd_errstr(status));
                mutex_enter(&sc->sc_lock);
                sc->sc_needed = 0;
                sc->sc_inflight = false;
                mutex_exit(&sc->sc_lock);
                return;
        }

        /* Get the transferred size.  */
        usbd_get_xfer_status(xfer, NULL, &pkt, &pktsize, NULL);
        KASSERTMSG(pktsize <= sc->sc_maxpktsize,
            "pktsize %"PRIu32" > %"PRIu16" (max)",
            pktsize, sc->sc_maxpktsize);

        /*
         * Enter the data, debit what we contributed from what we need,
         * mark the xfer as done, and reschedule the xfer if we still
         * need more.
         *
         * Must enter the data under the lock so it happens atomically
         * with updating sc_needed -- otherwise we might hang needing
         * entropy and not scheduling xfer.  Must not touch pkt after
         * clearing sc_inflight and possibly rescheduling the xfer.
         */
        mutex_enter(&sc->sc_lock);
        rnd_add_data(&sc->sc_rnd, pkt, pktsize, NBBY*pktsize);
        sc->sc_needed -= MIN(sc->sc_needed, pktsize);
        sc->sc_inflight = false;
        ualea_xfer(sc);
        mutex_exit(&sc->sc_lock);
}

MODULE(MODULE_CLASS_DRIVER, ualea, NULL);

#ifdef _MODULE
#include "ioconf.c"
#endif

static int
ualea_modcmd(modcmd_t cmd, void *aux)
{
        int error = 0;

        switch (cmd) {
        case MODULE_CMD_INIT:
#ifdef _MODULE
                error = config_init_component(cfdriver_ioconf_ualea,
                    cfattach_ioconf_ualea, cfdata_ioconf_ualea);
#endif
                return error;
        case MODULE_CMD_FINI:
#ifdef _MODULE
                error = config_fini_component(cfdriver_ioconf_ualea,
                    cfattach_ioconf_ualea, cfdata_ioconf_ualea);
#endif
                return error;
        default:
                return ENOTTY;
        }
}