1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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/cdefs.h>
36__FBSDID("$FreeBSD$");
37
38#include <sys/param.h>
39#include <sys/systm.h>
40#include <sys/bus.h>
41#include <sys/clock.h>
42#include <sys/kernel.h>
43#include <sys/lock.h>
44#include <sys/module.h>
45#include <sys/mutex.h>
46#include <sys/types.h>
47
48#include <dev/ofw/ofw_bus.h>
49#include <dev/ofw/ofw_bus_subr.h>
50
51#include <machine/bus.h>
52#include <machine/resource.h>
53#include <sys/rman.h>
54
55#include "clock_if.h"
56
57#define	GOLDFISH_RTC_TIME_LOW	0x00
58#define	GOLDFISH_RTC_TIME_HIGH	0x04
59
60struct goldfish_rtc_softc {
61	struct resource	*res;
62	int		rid;
63	struct mtx	mtx;
64};
65
66static int
67goldfish_rtc_probe(device_t dev)
68{
69
70	if (!ofw_bus_status_okay(dev))
71		return (ENXIO);
72
73	if (ofw_bus_is_compatible(dev, "google,goldfish-rtc")) {
74		device_set_desc(dev, "Goldfish RTC");
75		return (BUS_PROBE_DEFAULT);
76	}
77
78	return (ENXIO);
79}
80
81static int
82goldfish_rtc_attach(device_t dev)
83{
84	struct goldfish_rtc_softc *sc;
85
86	sc = device_get_softc(dev);
87
88	sc->rid = 0;
89	sc->res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &sc->rid,
90	    RF_ACTIVE);
91	if (sc->res == NULL) {
92		device_printf(dev, "could not allocate resource\n");
93		return (ENXIO);
94	}
95
96	mtx_init(&sc->mtx, device_get_nameunit(dev), NULL, MTX_DEF);
97
98	/*
99	 * Register as a system realtime clock with 1 second resolution.
100	 */
101	clock_register_flags(dev, 1000000, CLOCKF_SETTIME_NO_ADJ);
102	clock_schedule(dev, 1);
103
104	return (0);
105}
106
107static int
108goldfish_rtc_detach(device_t dev)
109{
110	struct goldfish_rtc_softc *sc;
111
112	sc = device_get_softc(dev);
113
114	clock_unregister(dev);
115	mtx_destroy(&sc->mtx);
116	bus_release_resource(dev, SYS_RES_MEMORY, sc->rid, sc->res);
117
118	return (0);
119}
120
121static int
122goldfish_rtc_gettime(device_t dev, struct timespec *ts)
123{
124	struct goldfish_rtc_softc *sc;
125	uint64_t low, high, nsec;
126
127	sc = device_get_softc(dev);
128
129	/*
130	 * Reading TIME_HIGH is defined in the documentation to give the high
131	 * 32 bits corresponding to the last TIME_LOW read, so must be done in
132	 * that order, but means we have atomicity guaranteed.
133	 */
134	mtx_lock(&sc->mtx);
135	low = bus_read_4(sc->res, GOLDFISH_RTC_TIME_LOW);
136	high = bus_read_4(sc->res, GOLDFISH_RTC_TIME_HIGH);
137	mtx_unlock(&sc->mtx);
138
139	nsec = (high << 32) | low;
140	ts->tv_sec = nsec / 1000000000;
141	ts->tv_nsec = nsec % 1000000000;
142
143	return (0);
144}
145
146static int
147goldfish_rtc_settime(device_t dev, struct timespec *ts)
148{
149	struct goldfish_rtc_softc *sc;
150	uint64_t nsec;
151
152	sc = device_get_softc(dev);
153
154	nsec = (uint64_t)ts->tv_sec * 1000000000 + ts->tv_nsec;
155
156	mtx_lock(&sc->mtx);
157	bus_write_4(sc->res, GOLDFISH_RTC_TIME_HIGH, nsec >> 32);
158	bus_write_4(sc->res, GOLDFISH_RTC_TIME_LOW, nsec);
159	mtx_unlock(&sc->mtx);
160
161	return (0);
162}
163
164static device_method_t goldfish_rtc_methods[] = {
165	/* Device interface */
166	DEVMETHOD(device_probe,		goldfish_rtc_probe),
167	DEVMETHOD(device_attach,	goldfish_rtc_attach),
168	DEVMETHOD(device_detach,	goldfish_rtc_detach),
169
170	/* Clock interface */
171	DEVMETHOD(clock_gettime,	goldfish_rtc_gettime),
172	DEVMETHOD(clock_settime,	goldfish_rtc_settime),
173
174	DEVMETHOD_END,
175};
176
177DEFINE_CLASS_0(goldfish_rtc, goldfish_rtc_driver, goldfish_rtc_methods,
178    sizeof(struct goldfish_rtc_softc));
179static devclass_t goldfish_rtc_devclass;
180
181DRIVER_MODULE(goldfish_rtc, simplebus, goldfish_rtc_driver,
182    goldfish_rtc_devclass, NULL, NULL);
183