/*      $OpenBSD: octrng.c,v 1.10 2022/04/06 18:59:27 naddy Exp $       */
/*
 * Copyright (c) 2013 Paul Irofti <paul@irofti.net>
 *
 * Permission to use, copy, modify, and/or 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.
 */

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

#include <machine/octeonvar.h>
#include <machine/octeonreg.h>
#include <octeon/dev/iobusvar.h>

int     octrng_match(struct device *, void *, void *);
void    octrng_attach(struct device *, struct device *, void *);
void    octrng_rnd(void *arg);

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

#define OCTRNG_MAP_SIZE 8ULL

/* OCTRNG_ENTROPY_ADDR 0x8001400000000000ULL */
#define OCTRNG_MAJORDID 8ULL
#define OCTRNG_ENTROPY_ADDR (((uint64_t)1 << 48) | \
                ((uint64_t)(OCTRNG_MAJORDID & 0x1f) << 43))
#define OCTRNG_ENTROPY_REG      0

#define OCTRNG_CONTROL_ADDR 0x0001180040000000ULL

#define OCTRNG_RESET (1ULL << 3)
#define OCTRNG_ENABLE_OUTPUT (1ULL << 1)
#define OCTRNG_ENABLE_ENTROPY (1ULL << 0)

struct octrng_softc {
        struct device sc_dev;
        struct timeout sc_to;
        struct iobus_attach_args *sc_io;

        bus_space_tag_t sc_iot;
        bus_space_handle_t sc_ioh;
};

const struct cfattach octrng_ca = {
        sizeof(struct octrng_softc), octrng_match, octrng_attach
};

struct cfdriver octrng_cd = {
        NULL, "octrng", DV_DULL
};


int
octrng_match(struct device *parent, void *match, void *aux)
{
        struct iobus_attach_args *aa = aux;
        struct cfdata *cf = match;

        /* XXX: check for board type */

        if (strcmp(aa->aa_name, cf->cf_driver->cd_name) != 0)
                return (0);

        return (1);
}

void
octrng_attach(struct device *parent, struct device *self, void *aux)
{
        struct octrng_softc *sc = (void *)self;
        sc->sc_io = aux;

        uint64_t control_reg;

        sc->sc_iot = sc->sc_io->aa_bust;

        if (bus_space_map(sc->sc_iot, OCTEON_RNG_BASE, OCTRNG_MAP_SIZE, 0,
            &sc->sc_ioh)) {
                printf(": can't map registers");
        }

        control_reg = octeon_xkphys_read_8(OCTRNG_CONTROL_ADDR);
        control_reg |= (OCTRNG_ENABLE_OUTPUT | OCTRNG_ENABLE_ENTROPY);
        octeon_xkphys_write_8(OCTRNG_CONTROL_ADDR, control_reg);

        timeout_set(&sc->sc_to, octrng_rnd, sc);

        timeout_add_sec(&sc->sc_to, 5);

        printf("\n");
}

void
octrng_rnd(void *arg)
{
        struct octrng_softc *sc = arg;
        uint64_t value;

        value = bus_space_read_8(sc->sc_iot, sc->sc_ioh, OCTRNG_ENTROPY_REG);

        DPRINTF(("%#llX ", value));     /* WARNING: very verbose */

        enqueue_randomness(value);
        timeout_add_msec(&sc->sc_to, 10);
}