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
57 struct goldfish_rtc_softc {
58 struct resource *res;
59 int rid;
60 struct mtx mtx;
61 };
62
63 static int
goldfish_rtc_probe(device_t dev)64 goldfish_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
78 static int
goldfish_rtc_attach(device_t dev)79 goldfish_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
104 static int
goldfish_rtc_detach(device_t dev)105 goldfish_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
118 static int
goldfish_rtc_gettime(device_t dev,struct timespec * ts)119 goldfish_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
143 static int
goldfish_rtc_settime(device_t dev,struct timespec * ts)144 goldfish_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
166 static 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
179 DEFINE_CLASS_0(goldfish_rtc, goldfish_rtc_driver, goldfish_rtc_methods,
180 sizeof(struct goldfish_rtc_softc));
181
182 DRIVER_MODULE(goldfish_rtc, simplebus, goldfish_rtc_driver, NULL, NULL);
183