/*- * SPDX-License-Identifier: BSD-2-Clause * * Copyright (c) 2021, Adrian Chadd * * 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 unmodified, 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 AUTHOR ``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 AUTHOR 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. */ /* Driver for Qualcomm MSM entropy device. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include struct qcom_rnd_softc { device_t dev; int reg_rid; struct resource *reg; }; static int qcom_rnd_modevent(module_t, int, void *); static int qcom_rnd_probe(device_t); static int qcom_rnd_attach(device_t); static int qcom_rnd_detach(device_t); static int qcom_rnd_harvest(struct qcom_rnd_softc *, void *, size_t *); static unsigned qcom_rnd_read(void *, unsigned); static struct random_source random_qcom_rnd = { .rs_ident = "Qualcomm Entropy Adapter", .rs_source = RANDOM_PURE_QUALCOMM, .rs_read = qcom_rnd_read, }; /* Kludge for API limitations of random(4). */ static _Atomic(struct qcom_rnd_softc *) g_qcom_rnd_softc; static int qcom_rnd_modevent(module_t mod, int type, void *unused) { int error; switch (type) { case MOD_LOAD: case MOD_QUIESCE: case MOD_UNLOAD: case MOD_SHUTDOWN: error = 0; break; default: error = EOPNOTSUPP; break; } return (error); } static int qcom_rnd_probe(device_t dev) { if (! ofw_bus_status_okay(dev)) { return (ENXIO); } if (ofw_bus_is_compatible(dev, "qcom,prng") == 0) { return (ENXIO); } return (0); } static int qcom_rnd_attach(device_t dev) { struct qcom_rnd_softc *sc, *exp; uint32_t reg; sc = device_get_softc(dev); /* Found a compatible device! */ sc->dev = dev; exp = NULL; if (!atomic_compare_exchange_strong_explicit(&g_qcom_rnd_softc, &exp, sc, memory_order_release, memory_order_acquire)) { return (ENXIO); } sc->reg_rid = 0; sc->reg = bus_alloc_resource_anywhere(dev, SYS_RES_MEMORY, &sc->reg_rid, 0x140, RF_ACTIVE); if (sc->reg == NULL) { device_printf(dev, "Couldn't allocate memory resource!\n"); return (ENXIO); } device_set_desc(dev, "Qualcomm PRNG"); /* * Check to see whether the PRNG has already been setup or not. */ bus_barrier(sc->reg, 0, 0x120, BUS_SPACE_BARRIER_READ); reg = bus_read_4(sc->reg, QCOM_RND_PRNG_CONFIG); if (reg & QCOM_RND_PRNG_CONFIG_HW_ENABLE) { device_printf(dev, "PRNG HW already enabled\n"); } else { /* * Do PRNG setup and then enable it. */ reg = bus_read_4(sc->reg, QCOM_RND_PRNG_LFSR_CFG); reg &= QCOM_RND_PRNG_LFSR_CFG_MASK; reg |= QCOM_RND_PRNG_LFSR_CFG_CLOCKS; bus_write_4(sc->reg, QCOM_RND_PRNG_LFSR_CFG, reg); bus_barrier(sc->reg, 0, 0x120, BUS_SPACE_BARRIER_WRITE); reg = bus_read_4(sc->reg, QCOM_RND_PRNG_CONFIG); reg |= QCOM_RND_PRNG_CONFIG_HW_ENABLE; bus_write_4(sc->reg, QCOM_RND_PRNG_CONFIG, reg); bus_barrier(sc->reg, 0, 0x120, BUS_SPACE_BARRIER_WRITE); } random_source_register(&random_qcom_rnd); return (0); } static int qcom_rnd_detach(device_t dev) { struct qcom_rnd_softc *sc; sc = device_get_softc(dev); KASSERT( atomic_load_explicit(&g_qcom_rnd_softc, memory_order_acquire) == sc, ("only one global instance at a time")); random_source_deregister(&random_qcom_rnd); if (sc->reg != NULL) { bus_release_resource(sc->dev, SYS_RES_MEMORY, sc->reg_rid, sc->reg); } atomic_store_explicit(&g_qcom_rnd_softc, NULL, memory_order_release); return (0); } static int qcom_rnd_harvest(struct qcom_rnd_softc *sc, void *buf, size_t *sz) { /* * Add data to buf until we either run out of entropy or we * fill the buffer. * * Note - be mindful of the provided buffer size; we're reading * 4 bytes at a time but we only want to supply up to the max * buffer size, so don't write past it! */ size_t rz = 0; uint32_t reg; while (rz < *sz) { bus_barrier(sc->reg, 0, 0x120, BUS_SPACE_BARRIER_READ); reg = bus_read_4(sc->reg, QCOM_RND_PRNG_STATUS); if ((reg & QCOM_RND_PRNG_STATUS_DATA_AVAIL) == 0) break; reg = bus_read_4(sc->reg, QCOM_RND_PRNG_DATA_OUT); memcpy(((char *) buf) + rz, ®, sizeof(uint32_t)); rz += sizeof(uint32_t); } if (rz == 0) return (EAGAIN); *sz = rz; return (0); } static unsigned qcom_rnd_read(void *buf, unsigned usz) { struct qcom_rnd_softc *sc; size_t sz; int error; sc = g_qcom_rnd_softc; if (sc == NULL) return (0); sz = usz; error = qcom_rnd_harvest(sc, buf, &sz); if (error != 0) return (0); return (sz); } static device_method_t qcom_rnd_methods[] = { /* Device methods. */ DEVMETHOD(device_probe, qcom_rnd_probe), DEVMETHOD(device_attach, qcom_rnd_attach), DEVMETHOD(device_detach, qcom_rnd_detach), DEVMETHOD_END }; static driver_t qcom_rnd_driver = { "qcom_rnd", qcom_rnd_methods, sizeof(struct qcom_rnd_softc) }; DRIVER_MODULE(qcom_rnd_random, simplebus, qcom_rnd_driver, qcom_rnd_modevent, 0); DRIVER_MODULE(qcom_rnd_random, ofwbus, qcom_rnd_driver, qcom_rnd_modevent, 0); MODULE_DEPEND(qcom_rnd_random, random_device, 1, 1, 1); MODULE_VERSION(qcom_rnd_random, 1);