/* $NetBSD: bcm2835_rng.c,v 1.10 2014/08/10 16:44:33 tls Exp $ */ /*- * Copyright (c) 2013 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jared D. McNeill * * 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 __KERNEL_RCSID(0, "$NetBSD: bcm2835_rng.c,v 1.10 2014/08/10 16:44:33 tls Exp $"); #include #include #include #include #include #include #include #include #include #include #include #define RNG_CTRL 0x00 #define RNG_CTRL_EN __BIT(0) #define RNG_STATUS 0x04 #define RNG_STATUS_CNT __BITS(31,24) #define RNG_DATA 0x08 #define RNG_DATA_MAX 256 struct bcm2835rng_softc { device_t sc_dev; bus_space_tag_t sc_iot; bus_space_handle_t sc_ioh; kmutex_t sc_intr_lock; unsigned int sc_bytes_wanted; void *sc_sih; kmutex_t sc_rnd_lock; krndsource_t sc_rndsource; }; static int bcmrng_match(device_t, cfdata_t, void *); static void bcmrng_attach(device_t, device_t, void *); static void bcmrng_get(struct bcm2835rng_softc *); static void bcmrng_get_cb(size_t, void *); static void bcmrng_get_intr(void *); CFATTACH_DECL_NEW(bcmrng_amba, sizeof(struct bcm2835rng_softc), bcmrng_match, bcmrng_attach, NULL, NULL); /* ARGSUSED */ static int bcmrng_match(device_t parent, cfdata_t match, void *aux) { struct amba_attach_args *aaa = aux; if (strcmp(aaa->aaa_name, "bcmrng") != 0) return 0; return 1; } static void bcmrng_attach(device_t parent, device_t self, void *aux) { struct bcm2835rng_softc *sc = device_private(self); struct amba_attach_args *aaa = aux; uint32_t ctrl; aprint_naive("\n"); aprint_normal(": RNG\n"); sc->sc_dev = self; sc->sc_iot = aaa->aaa_iot; if (bus_space_map(aaa->aaa_iot, aaa->aaa_addr, BCM2835_RNG_SIZE, 0, &sc->sc_ioh)) { aprint_error_dev(sc->sc_dev, "unable to map device\n"); goto fail0; } /* discard initial numbers, broadcom says they are "less random" */ bus_space_write_4(sc->sc_iot, sc->sc_ioh, RNG_STATUS, 0x40000); /* enable rng */ ctrl = bus_space_read_4(sc->sc_iot, sc->sc_ioh, RNG_CTRL); ctrl |= RNG_CTRL_EN; bus_space_write_4(sc->sc_iot, sc->sc_ioh, RNG_CTRL, ctrl); /* set up a softint for adding data */ mutex_init(&sc->sc_intr_lock, MUTEX_DEFAULT, IPL_SERIAL); sc->sc_bytes_wanted = 0; sc->sc_sih = softint_establish(SOFTINT_SERIAL|SOFTINT_MPSAFE, &bcmrng_get_intr, sc); if (sc->sc_sih == NULL) { aprint_error_dev(sc->sc_dev, "unable to establish softint"); goto fail1; } /* set up an rndsource */ mutex_init(&sc->sc_rnd_lock, MUTEX_DEFAULT, IPL_SERIAL); rndsource_setcb(&sc->sc_rndsource, &bcmrng_get_cb, sc); rnd_attach_source(&sc->sc_rndsource, device_xname(self), RND_TYPE_RNG, RND_FLAG_COLLECT_VALUE|RND_FLAG_HASCB); /* get some initial entropy ASAP */ bcmrng_get_cb(RND_POOLBITS / NBBY, sc); /* Success! */ return; fail1: mutex_destroy(&sc->sc_intr_lock); bus_space_unmap(aaa->aaa_iot, sc->sc_ioh, BCM2835_RNG_SIZE); fail0: return; } static void bcmrng_get(struct bcm2835rng_softc *sc) { uint32_t status, cnt; uint32_t buf[RNG_DATA_MAX]; /* 1k on the stack */ mutex_spin_enter(&sc->sc_intr_lock); while (sc->sc_bytes_wanted) { status = bus_space_read_4(sc->sc_iot, sc->sc_ioh, RNG_STATUS); cnt = __SHIFTOUT(status, RNG_STATUS_CNT); KASSERT(cnt < RNG_DATA_MAX); if (cnt == 0) continue; /* XXX Busy-waiting seems wrong... */ bus_space_read_multi_4(sc->sc_iot, sc->sc_ioh, RNG_DATA, buf, cnt); /* * This lock dance is necessary because rnd_add_data * may call bcmrng_get_cb which takes the intr lock. */ mutex_spin_exit(&sc->sc_intr_lock); mutex_spin_enter(&sc->sc_rnd_lock); rnd_add_data(&sc->sc_rndsource, buf, (cnt * 4), (cnt * 4 * NBBY)); mutex_spin_exit(&sc->sc_rnd_lock); mutex_spin_enter(&sc->sc_intr_lock); sc->sc_bytes_wanted -= MIN(sc->sc_bytes_wanted, (cnt * 4)); } explicit_memset(buf, 0, sizeof(buf)); mutex_spin_exit(&sc->sc_intr_lock); } static void bcmrng_get_cb(size_t bytes_wanted, void *arg) { struct bcm2835rng_softc *sc = arg; /* * Deferring to a softint is necessary until the rnd(9) locking * is fixed. */ mutex_spin_enter(&sc->sc_intr_lock); if (sc->sc_bytes_wanted == 0) softint_schedule(sc->sc_sih); if (bytes_wanted > (UINT_MAX - sc->sc_bytes_wanted)) sc->sc_bytes_wanted = UINT_MAX; else sc->sc_bytes_wanted += bytes_wanted; mutex_spin_exit(&sc->sc_intr_lock); } static void bcmrng_get_intr(void *arg) { struct bcm2835rng_softc *const sc = arg; bcmrng_get(sc); }