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/cdefs.h>
36 #include <sys/param.h>
37 #include <sys/systm.h>
38 #include <sys/bus.h>
39 #include <sys/clock.h>
40 #include <sys/kernel.h>
41 #include <sys/lock.h>
42 #include <sys/module.h>
43 #include <sys/mutex.h>
44 #include <sys/types.h>
45
46 #include <dev/ofw/ofw_bus.h>
47 #include <dev/ofw/ofw_bus_subr.h>
48
49 #include <machine/bus.h>
50 #include <machine/resource.h>
51 #include <sys/rman.h>
52
53 #include "clock_if.h"
54
55 #define GOLDFISH_RTC_TIME_LOW 0x00
56 #define GOLDFISH_RTC_TIME_HIGH 0x04
57
58 struct goldfish_rtc_softc {
59 struct resource *res;
60 int rid;
61 struct mtx mtx;
62 };
63
64 static int
goldfish_rtc_probe(device_t dev)65 goldfish_rtc_probe(device_t dev)
66 {
67
68 if (!ofw_bus_status_okay(dev))
69 return (ENXIO);
70
71 if (ofw_bus_is_compatible(dev, "google,goldfish-rtc")) {
72 device_set_desc(dev, "Goldfish RTC");
73 return (BUS_PROBE_DEFAULT);
74 }
75
76 return (ENXIO);
77 }
78
79 static int
goldfish_rtc_attach(device_t dev)80 goldfish_rtc_attach(device_t dev)
81 {
82 struct goldfish_rtc_softc *sc;
83
84 sc = device_get_softc(dev);
85
86 sc->rid = 0;
87 sc->res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &sc->rid,
88 RF_ACTIVE);
89 if (sc->res == NULL) {
90 device_printf(dev, "could not allocate resource\n");
91 return (ENXIO);
92 }
93
94 mtx_init(&sc->mtx, device_get_nameunit(dev), NULL, MTX_DEF);
95
96 /*
97 * Register as a system realtime clock with 1 second resolution.
98 */
99 clock_register_flags(dev, 1000000, CLOCKF_SETTIME_NO_ADJ);
100 clock_schedule(dev, 1);
101
102 return (0);
103 }
104
105 static int
goldfish_rtc_detach(device_t dev)106 goldfish_rtc_detach(device_t dev)
107 {
108 struct goldfish_rtc_softc *sc;
109
110 sc = device_get_softc(dev);
111
112 clock_unregister(dev);
113 mtx_destroy(&sc->mtx);
114 bus_release_resource(dev, SYS_RES_MEMORY, sc->rid, sc->res);
115
116 return (0);
117 }
118
119 static int
goldfish_rtc_gettime(device_t dev,struct timespec * ts)120 goldfish_rtc_gettime(device_t dev, struct timespec *ts)
121 {
122 struct goldfish_rtc_softc *sc;
123 uint64_t low, high, nsec;
124
125 sc = device_get_softc(dev);
126
127 /*
128 * Reading TIME_HIGH is defined in the documentation to give the high
129 * 32 bits corresponding to the last TIME_LOW read, so must be done in
130 * that order, but means we have atomicity guaranteed.
131 */
132 mtx_lock(&sc->mtx);
133 low = bus_read_4(sc->res, GOLDFISH_RTC_TIME_LOW);
134 high = bus_read_4(sc->res, GOLDFISH_RTC_TIME_HIGH);
135 mtx_unlock(&sc->mtx);
136
137 nsec = (high << 32) | low;
138 ts->tv_sec = nsec / 1000000000;
139 ts->tv_nsec = nsec % 1000000000;
140
141 return (0);
142 }
143
144 static int
goldfish_rtc_settime(device_t dev,struct timespec * ts)145 goldfish_rtc_settime(device_t dev, struct timespec *ts)
146 {
147 struct goldfish_rtc_softc *sc;
148 uint64_t nsec;
149
150 sc = device_get_softc(dev);
151
152 /*
153 * We request a timespec with no resolution-adjustment. That also
154 * disables utc adjustment, so apply that ourselves.
155 */
156 ts->tv_sec -= utc_offset();
157 nsec = (uint64_t)ts->tv_sec * 1000000000 + ts->tv_nsec;
158
159 mtx_lock(&sc->mtx);
160 bus_write_4(sc->res, GOLDFISH_RTC_TIME_HIGH, nsec >> 32);
161 bus_write_4(sc->res, GOLDFISH_RTC_TIME_LOW, nsec);
162 mtx_unlock(&sc->mtx);
163
164 return (0);
165 }
166
167 static device_method_t goldfish_rtc_methods[] = {
168 /* Device interface */
169 DEVMETHOD(device_probe, goldfish_rtc_probe),
170 DEVMETHOD(device_attach, goldfish_rtc_attach),
171 DEVMETHOD(device_detach, goldfish_rtc_detach),
172
173 /* Clock interface */
174 DEVMETHOD(clock_gettime, goldfish_rtc_gettime),
175 DEVMETHOD(clock_settime, goldfish_rtc_settime),
176
177 DEVMETHOD_END,
178 };
179
180 DEFINE_CLASS_0(goldfish_rtc, goldfish_rtc_driver, goldfish_rtc_methods,
181 sizeof(struct goldfish_rtc_softc));
182 static devclass_t goldfish_rtc_devclass;
183
184 DRIVER_MODULE(goldfish_rtc, simplebus, goldfish_rtc_driver,
185 goldfish_rtc_devclass, NULL, NULL);
186