144 lines
4.4 KiB
C
144 lines
4.4 KiB
C
/* $NetBSD: bcm2835_rng.c,v 1.12 2016/12/17 15:24:35 riastradh Exp $ */
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/*-
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* Copyright (c) 2013 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Jared D. McNeill
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__KERNEL_RCSID(0, "$NetBSD: bcm2835_rng.c,v 1.12 2016/12/17 15:24:35 riastradh Exp $");
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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/kernel.h>
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#include <sys/bus.h>
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#include <sys/rndpool.h>
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#include <sys/rndsource.h>
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#include <arm/broadcom/bcm_amba.h>
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#include <arm/broadcom/bcm2835reg.h>
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#include <arm/broadcom/bcm2835_intr.h>
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#define RNG_CTRL 0x00
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#define RNG_CTRL_EN __BIT(0)
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#define RNG_STATUS 0x04
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#define RNG_STATUS_CNT __BITS(31,24)
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#define RNG_DATA 0x08
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#define RNG_DATA_MAX 256
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struct bcm2835rng_softc {
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device_t 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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kmutex_t sc_lock;
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krndsource_t sc_rndsource;
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};
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static int bcmrng_match(device_t, cfdata_t, void *);
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static void bcmrng_attach(device_t, device_t, void *);
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static void bcmrng_get(size_t, void *);
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CFATTACH_DECL_NEW(bcmrng_amba, sizeof(struct bcm2835rng_softc),
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bcmrng_match, bcmrng_attach, NULL, NULL);
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/* ARGSUSED */
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static int
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bcmrng_match(device_t parent, cfdata_t match, void *aux)
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{
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struct amba_attach_args *aaa = aux;
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if (strcmp(aaa->aaa_name, "bcmrng") != 0)
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return 0;
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return 1;
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}
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static void
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bcmrng_attach(device_t parent, device_t self, void *aux)
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{
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struct bcm2835rng_softc *sc = device_private(self);
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struct amba_attach_args *aaa = aux;
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uint32_t ctrl;
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aprint_naive("\n");
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aprint_normal(": RNG\n");
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sc->sc_dev = self;
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sc->sc_iot = aaa->aaa_iot;
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if (bus_space_map(aaa->aaa_iot, aaa->aaa_addr, BCM2835_RNG_SIZE, 0,
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&sc->sc_ioh)) {
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aprint_error_dev(sc->sc_dev, "unable to map device\n");
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return;
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}
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/* discard initial numbers, broadcom says they are "less random" */
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bus_space_write_4(sc->sc_iot, sc->sc_ioh, RNG_STATUS, 0x40000);
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/* enable rng */
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ctrl = bus_space_read_4(sc->sc_iot, sc->sc_ioh, RNG_CTRL);
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ctrl |= RNG_CTRL_EN;
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bus_space_write_4(sc->sc_iot, sc->sc_ioh, RNG_CTRL, ctrl);
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/* set up an rndsource */
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mutex_init(&sc->sc_lock, MUTEX_DEFAULT, IPL_VM);
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rndsource_setcb(&sc->sc_rndsource, &bcmrng_get, sc);
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rnd_attach_source(&sc->sc_rndsource, device_xname(self), RND_TYPE_RNG,
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RND_FLAG_COLLECT_VALUE|RND_FLAG_HASCB);
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/* get some initial entropy ASAP */
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bcmrng_get(RND_POOLBITS / NBBY, sc);
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}
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static void
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bcmrng_get(size_t bytes_wanted, void *arg)
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{
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struct bcm2835rng_softc *sc = arg;
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uint32_t status, cnt;
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uint32_t buf[RNG_DATA_MAX]; /* 1k on the stack */
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mutex_spin_enter(&sc->sc_lock);
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while (bytes_wanted) {
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status = bus_space_read_4(sc->sc_iot, sc->sc_ioh, RNG_STATUS);
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cnt = __SHIFTOUT(status, RNG_STATUS_CNT);
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KASSERT(cnt < RNG_DATA_MAX);
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if (cnt == 0)
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continue; /* XXX Busy-waiting seems wrong... */
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bus_space_read_multi_4(sc->sc_iot, sc->sc_ioh, RNG_DATA, buf,
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cnt);
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rnd_add_data_sync(&sc->sc_rndsource, buf, (cnt * 4),
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(cnt * 4 * NBBY));
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bytes_wanted -= MIN(bytes_wanted, (cnt * 4));
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}
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explicit_memset(buf, 0, sizeof(buf));
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mutex_spin_exit(&sc->sc_lock);
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}
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