114 lines
2.9 KiB
C
114 lines
2.9 KiB
C
/* $OpenBSD: bcm2835_rng.c,v 1.4 2021/10/24 17:52:26 mpi Exp $ */
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/*
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* Copyright (c) 2018 Mark Kettenis <kettenis@openbsd.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/device.h>
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#include <sys/timeout.h>
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#include <machine/bus.h>
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#include <machine/fdt.h>
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#include <dev/ofw/openfirm.h>
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#include <dev/ofw/fdt.h>
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/* Registers */
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#define RNG_CTRL 0x0000
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#define RNG_CTRL_EN (1 << 0)
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#define RNG_STATUS 0x0004
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#define RNG_STATUS_COUNT(x) ((x) >> 24)
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#define RNG_DATA 0x0008
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#define HREAD4(sc, reg) \
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(bus_space_read_4((sc)->sc_iot, (sc)->sc_ioh, (reg)))
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#define HWRITE4(sc, reg, val) \
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bus_space_write_4((sc)->sc_iot, (sc)->sc_ioh, (reg), (val))
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struct bcmrng_softc {
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struct device sc_dev;
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bus_space_tag_t sc_iot;
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bus_space_handle_t sc_ioh;
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struct timeout sc_to;
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};
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int bcmrng_match(struct device *, void *, void *);
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void bcmrng_attach(struct device *, struct device *, void *);
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const struct cfattach bcmrng_ca = {
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sizeof (struct bcmrng_softc), bcmrng_match, bcmrng_attach
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};
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struct cfdriver bcmrng_cd = {
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NULL, "bcmrng", DV_DULL
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};
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void bcmrng_rnd(void *);
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int
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bcmrng_match(struct device *parent, void *match, void *aux)
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{
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struct fdt_attach_args *faa = aux;
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return OF_is_compatible(faa->fa_node, "brcm,bcm2835-rng");
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}
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void
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bcmrng_attach(struct device *parent, struct device *self, void *aux)
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{
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struct bcmrng_softc *sc = (struct bcmrng_softc *)self;
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struct fdt_attach_args *faa = aux;
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if (faa->fa_nreg < 1) {
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printf(": no registers\n");
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return;
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}
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sc->sc_iot = faa->fa_iot;
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if (bus_space_map(sc->sc_iot, faa->fa_reg[0].addr,
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faa->fa_reg[0].size, 0, &sc->sc_ioh)) {
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printf(": can't map registers\n");
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return;
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}
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printf("\n");
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/* Discard initial numbers which may be "less" random. */
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HWRITE4(sc, RNG_STATUS, 250000);
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HWRITE4(sc, RNG_CTRL, RNG_CTRL_EN);
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timeout_set(&sc->sc_to, bcmrng_rnd, sc);
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bcmrng_rnd(sc);
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}
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void
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bcmrng_rnd(void *arg)
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{
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struct bcmrng_softc *sc = arg;
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uint32_t status, data;
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int i, count;
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status = HREAD4(sc, RNG_STATUS);
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count = MIN(4, RNG_STATUS_COUNT(status));
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for (i = 0; i < count; i++) {
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data = HREAD4(sc, RNG_DATA);
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enqueue_randomness(data);
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}
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timeout_add_sec(&sc->sc_to, 1);
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}
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