g2rtc.c revision 1.9 
1/* $NetBSD: g2rtc.c,v 1.9 2025/09/07 21:45:12 thorpej Exp $ */
2
3/*-
4 * Copyright (c) 2002 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
19 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__KERNEL_RCSID(0, "$NetBSD: g2rtc.c,v 1.9 2025/09/07 21:45:12 thorpej Exp $");
31
32#include <sys/param.h>
33#include <sys/systm.h>
34#include <sys/device.h>
35#include <sys/bus.h>
36
37#include <dev/clock_subr.h>
38
39#include <dreamcast/dev/g2/g2busvar.h>
40
41
42#define G2RTC_REG_BASE	0x00710000
43#define G2RTC_REG_SIZE	12
44
45/* Offset by 20 years, 5 of them are leap */
46#define G2RTC_OFFSET	(20 * SECS_PER_COMMON_YEAR + 5 * SECS_PER_DAY)
47
48struct g2rtc_softc {
49	device_t sc_dev;
50
51	bus_space_tag_t sc_bt;
52	bus_space_handle_t sc_bh;
53	struct todr_chip_handle sc_tch;
54};
55
56/* autoconf glue */
57static int g2rtc_match(device_t, cfdata_t, void *);
58static void g2rtc_attach(device_t, device_t, void *);
59
60CFATTACH_DECL_NEW(g2rtc, sizeof(struct g2rtc_softc),
61    g2rtc_match, g2rtc_attach, NULL, NULL);
62
63
64/* todr(9) methods */
65static int g2rtc_todr_gettime(todr_chip_handle_t, struct timeval *);
66static int g2rtc_todr_settime(todr_chip_handle_t, struct timeval *);
67
68static inline uint32_t g2rtc_read(bus_space_tag_t, bus_space_handle_t);
69
70
71static int
72g2rtc_match(device_t parent, cfdata_t cf, void *aux)
73{
74	static int g2rtc_matched = 0;
75
76	if (g2rtc_matched)
77		return 0;
78
79	g2rtc_matched = 1;
80	return 1;
81}
82
83
84static void
85g2rtc_attach(device_t parent, device_t self, void *aux)
86{
87	struct g2rtc_softc *sc = device_private(self);
88	struct g2bus_attach_args *ga = aux;
89	todr_chip_handle_t tch;
90
91	sc->sc_dev = self;
92	sc->sc_bt = ga->ga_memt;
93	if (bus_space_map(sc->sc_bt, G2RTC_REG_BASE, G2RTC_REG_SIZE, 0,
94	    &sc->sc_bh) != 0) {
95		printf(": unable to map registers\n");
96		return;
97	}
98	printf(": time-of-day clock\n");
99
100	tch = &sc->sc_tch;
101	tch->todr_dev = self;
102	tch->todr_gettime = g2rtc_todr_gettime;
103	tch->todr_settime = g2rtc_todr_settime;
104	todr_attach(tch);
105}
106
107
108static inline uint32_t
109g2rtc_read(bus_space_tag_t bt, bus_space_handle_t bh)
110{
111
112	return ((bus_space_read_4(bt, bh, 0) & 0xffff) << 16)
113	    | (bus_space_read_4(bt, bh, 4) & 0xffff);
114}
115
116
117/*
118 * Get time-of-day and convert to `struct timeval'.
119 * Return 0 on success; an error number otherwise.
120 */
121static int
122g2rtc_todr_gettime(todr_chip_handle_t handle, struct timeval *tv)
123{
124	struct g2rtc_softc *sc = device_private(handle->todr_dev);
125	uint32_t new, old;
126	int i;
127
128	for (old = 0;;) {
129		for (i = 0; i < 3; i++) {
130			new = g2rtc_read(sc->sc_bt, sc->sc_bh);
131			if (new != old)
132				break;
133		}
134		if (i < 3)
135			old = new;
136		else
137			break;
138	}
139
140	tv->tv_sec = new - G2RTC_OFFSET;
141	tv->tv_usec = 0;
142
143	return 0;
144}
145
146
147/*
148 * Set the time-of-day clock based on the value of the `struct timeval' arg.
149 * Return 0 on success; an error number otherwise.
150 */
151static int
152g2rtc_todr_settime(todr_chip_handle_t handle, struct timeval *tv)
153{
154	struct g2rtc_softc *sc = device_private(handle->todr_dev);
155	uint32_t secs;
156	int i, retry;
157
158	secs = (uint32_t)tv->tv_sec + G2RTC_OFFSET;
159
160	for (retry = 0; retry < 5; retry++) {
161
162		/* Don't change the order */
163		bus_space_write_4(sc->sc_bt, sc->sc_bh, 8, 1);
164		bus_space_write_4(sc->sc_bt, sc->sc_bh, 4, secs & 0xffff);
165		bus_space_write_4(sc->sc_bt, sc->sc_bh, 0, secs >> 16);
166
167		/* verify */
168		for (i = 0; i < 3; i++)
169			if (g2rtc_read(sc->sc_bt, sc->sc_bh) == secs)
170				return 0; /* ok */
171	}
172
173	return EIO;
174}
175