1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2020 Jessica Clarke <jrtc27@FreeBSD.org>
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28/*
29 * RTC for the goldfish virtual hardware platform implemented in QEMU,
30 * initially for Android but now also used for RISC-V's virt machine.
31 *
32 * https://android.googlesource.com/platform/external/qemu/+/master/docs/GOLDFISH-VIRTUAL-HARDWARE.TXT
33 */
34
35#include <sys/param.h>
36#include <sys/systm.h>
37#include <sys/bus.h>
38#include <sys/clock.h>
39#include <sys/kernel.h>
40#include <sys/lock.h>
41#include <sys/module.h>
42#include <sys/mutex.h>
43#include <sys/types.h>
44
45#include <dev/ofw/ofw_bus.h>
46#include <dev/ofw/ofw_bus_subr.h>
47
48#include <machine/bus.h>
49#include <machine/resource.h>
50#include <sys/rman.h>
51
52#include "clock_if.h"
53
54#define	GOLDFISH_RTC_TIME_LOW	0x00
55#define	GOLDFISH_RTC_TIME_HIGH	0x04
56
57struct goldfish_rtc_softc {
58	struct resource	*res;
59	int		rid;
60	struct mtx	mtx;
61};
62
63static int
64goldfish_rtc_probe(device_t dev)
65{
66
67	if (!ofw_bus_status_okay(dev))
68		return (ENXIO);
69
70	if (ofw_bus_is_compatible(dev, "google,goldfish-rtc")) {
71		device_set_desc(dev, "Goldfish RTC");
72		return (BUS_PROBE_DEFAULT);
73	}
74
75	return (ENXIO);
76}
77
78static int
79goldfish_rtc_attach(device_t dev)
80{
81	struct goldfish_rtc_softc *sc;
82
83	sc = device_get_softc(dev);
84
85	sc->rid = 0;
86	sc->res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &sc->rid,
87	    RF_ACTIVE);
88	if (sc->res == NULL) {
89		device_printf(dev, "could not allocate resource\n");
90		return (ENXIO);
91	}
92
93	mtx_init(&sc->mtx, device_get_nameunit(dev), NULL, MTX_DEF);
94
95	/*
96	 * Register as a system realtime clock with 1 second resolution.
97	 */
98	clock_register_flags(dev, 1000000, CLOCKF_SETTIME_NO_ADJ);
99	clock_schedule(dev, 1);
100
101	return (0);
102}
103
104static int
105goldfish_rtc_detach(device_t dev)
106{
107	struct goldfish_rtc_softc *sc;
108
109	sc = device_get_softc(dev);
110
111	clock_unregister(dev);
112	mtx_destroy(&sc->mtx);
113	bus_release_resource(dev, SYS_RES_MEMORY, sc->rid, sc->res);
114
115	return (0);
116}
117
118static int
119goldfish_rtc_gettime(device_t dev, struct timespec *ts)
120{
121	struct goldfish_rtc_softc *sc;
122	uint64_t low, high, nsec;
123
124	sc = device_get_softc(dev);
125
126	/*
127	 * Reading TIME_HIGH is defined in the documentation to give the high
128	 * 32 bits corresponding to the last TIME_LOW read, so must be done in
129	 * that order, but means we have atomicity guaranteed.
130	 */
131	mtx_lock(&sc->mtx);
132	low = bus_read_4(sc->res, GOLDFISH_RTC_TIME_LOW);
133	high = bus_read_4(sc->res, GOLDFISH_RTC_TIME_HIGH);
134	mtx_unlock(&sc->mtx);
135
136	nsec = (high << 32) | low;
137	ts->tv_sec = nsec / 1000000000;
138	ts->tv_nsec = nsec % 1000000000;
139
140	return (0);
141}
142
143static int
144goldfish_rtc_settime(device_t dev, struct timespec *ts)
145{
146	struct goldfish_rtc_softc *sc;
147	uint64_t nsec;
148
149	sc = device_get_softc(dev);
150
151	/*
152	 * We request a timespec with no resolution-adjustment.  That also
153	 * disables utc adjustment, so apply that ourselves.
154	 */
155	ts->tv_sec -= utc_offset();
156	nsec = (uint64_t)ts->tv_sec * 1000000000 + ts->tv_nsec;
157
158	mtx_lock(&sc->mtx);
159	bus_write_4(sc->res, GOLDFISH_RTC_TIME_HIGH, nsec >> 32);
160	bus_write_4(sc->res, GOLDFISH_RTC_TIME_LOW, nsec);
161	mtx_unlock(&sc->mtx);
162
163	return (0);
164}
165
166static device_method_t goldfish_rtc_methods[] = {
167	/* Device interface */
168	DEVMETHOD(device_probe,		goldfish_rtc_probe),
169	DEVMETHOD(device_attach,	goldfish_rtc_attach),
170	DEVMETHOD(device_detach,	goldfish_rtc_detach),
171
172	/* Clock interface */
173	DEVMETHOD(clock_gettime,	goldfish_rtc_gettime),
174	DEVMETHOD(clock_settime,	goldfish_rtc_settime),
175
176	DEVMETHOD_END,
177};
178
179DEFINE_CLASS_0(goldfish_rtc, goldfish_rtc_driver, goldfish_rtc_methods,
180    sizeof(struct goldfish_rtc_softc));
181
182DRIVER_MODULE(goldfish_rtc, simplebus, goldfish_rtc_driver, NULL, NULL);
183