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goldfish_rtc.c
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Editing: goldfish_rtc.c
/*- * SPDX-License-Identifier: BSD-2-Clause-FreeBSD * * Copyright (c) 2020 Jessica Clarke <jrtc27@FreeBSD.org> * * 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 AUTHOR 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 AUTHOR 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. */ /* * RTC for the goldfish virtual hardware platform implemented in QEMU, * initially for Android but now also used for RISC-V's virt machine. * * https://android.googlesource.com/platform/external/qemu/+/master/docs/GOLDFISH-VIRTUAL-HARDWARE.TXT */ #include <sys/cdefs.h> __FBSDID("$FreeBSD$"); #include <sys/param.h> #include <sys/systm.h> #include <sys/bus.h> #include <sys/clock.h> #include <sys/kernel.h> #include <sys/lock.h> #include <sys/module.h> #include <sys/mutex.h> #include <sys/types.h> #include <dev/ofw/ofw_bus.h> #include <dev/ofw/ofw_bus_subr.h> #include <machine/bus.h> #include <machine/resource.h> #include <sys/rman.h> #include "clock_if.h" #define GOLDFISH_RTC_TIME_LOW 0x00 #define GOLDFISH_RTC_TIME_HIGH 0x04 struct goldfish_rtc_softc { struct resource *res; int rid; struct mtx mtx; }; static int goldfish_rtc_probe(device_t dev) { if (!ofw_bus_status_okay(dev)) return (ENXIO); if (ofw_bus_is_compatible(dev, "google,goldfish-rtc")) { device_set_desc(dev, "Goldfish RTC"); return (BUS_PROBE_DEFAULT); } return (ENXIO); } static int goldfish_rtc_attach(device_t dev) { struct goldfish_rtc_softc *sc; sc = device_get_softc(dev); sc->rid = 0; sc->res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &sc->rid, RF_ACTIVE); if (sc->res == NULL) { device_printf(dev, "could not allocate resource\n"); return (ENXIO); } mtx_init(&sc->mtx, device_get_nameunit(dev), NULL, MTX_DEF); /* * Register as a system realtime clock with 1 second resolution. */ clock_register_flags(dev, 1000000, CLOCKF_SETTIME_NO_ADJ); clock_schedule(dev, 1); return (0); } static int goldfish_rtc_detach(device_t dev) { struct goldfish_rtc_softc *sc; sc = device_get_softc(dev); clock_unregister(dev); mtx_destroy(&sc->mtx); bus_release_resource(dev, SYS_RES_MEMORY, sc->rid, sc->res); return (0); } static int goldfish_rtc_gettime(device_t dev, struct timespec *ts) { struct goldfish_rtc_softc *sc; uint64_t low, high, nsec; sc = device_get_softc(dev); /* * Reading TIME_HIGH is defined in the documentation to give the high * 32 bits corresponding to the last TIME_LOW read, so must be done in * that order, but means we have atomicity guaranteed. */ mtx_lock(&sc->mtx); low = bus_read_4(sc->res, GOLDFISH_RTC_TIME_LOW); high = bus_read_4(sc->res, GOLDFISH_RTC_TIME_HIGH); mtx_unlock(&sc->mtx); nsec = (high << 32) | low; ts->tv_sec = nsec / 1000000000; ts->tv_nsec = nsec % 1000000000; return (0); } static int goldfish_rtc_settime(device_t dev, struct timespec *ts) { struct goldfish_rtc_softc *sc; uint64_t nsec; sc = device_get_softc(dev); nsec = (uint64_t)ts->tv_sec * 1000000000 + ts->tv_nsec; mtx_lock(&sc->mtx); bus_write_4(sc->res, GOLDFISH_RTC_TIME_HIGH, nsec >> 32); bus_write_4(sc->res, GOLDFISH_RTC_TIME_LOW, nsec); mtx_unlock(&sc->mtx); return (0); } static device_method_t goldfish_rtc_methods[] = { /* Device interface */ DEVMETHOD(device_probe, goldfish_rtc_probe), DEVMETHOD(device_attach, goldfish_rtc_attach), DEVMETHOD(device_detach, goldfish_rtc_detach), /* Clock interface */ DEVMETHOD(clock_gettime, goldfish_rtc_gettime), DEVMETHOD(clock_settime, goldfish_rtc_settime), DEVMETHOD_END, }; DEFINE_CLASS_0(goldfish_rtc, goldfish_rtc_driver, goldfish_rtc_methods, sizeof(struct goldfish_rtc_softc)); static devclass_t goldfish_rtc_devclass; DRIVER_MODULE(goldfish_rtc, simplebus, goldfish_rtc_driver, goldfish_rtc_devclass, NULL, NULL);
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