g2rtc.c revision 1.3 
1/* $NetBSD: g2rtc.c,v 1.3 2008/04/28 20:23:16 martin 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 1.3 2008/04/28 20:23:16 martin Exp $");
31
32#include <sys/param.h>
33#include <sys/systm.h>
34#include <sys/device.h>
35
36#include <dev/clock_subr.h>
37
38#include <machine/bus.h>
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 * SECYR + 5 * SECDAY)
47
48struct g2rtc_softc {
49	struct device sc_dev;
50
51	bus_space_tag_t sc_bt;
52	bus_space_handle_t sc_bh;
53};
54
55/* autoconf glue */
56static int g2rtc_match(struct device *, struct cfdata *, void *);
57static void g2rtc_attach(struct device *, struct device *, void *);
58
59CFATTACH_DECL(g2rtc, sizeof(struct g2rtc_softc),
60	      g2rtc_match, g2rtc_attach, NULL, NULL);
61
62
63/* todr(9) methods */
64static int g2rtc_todr_gettime(todr_chip_handle_t, volatile struct timeval *);
65static int g2rtc_todr_settime(todr_chip_handle_t, volatile struct timeval *);
66
67static struct todr_chip_handle g2rtc_todr_handle = {
68	.cookie       = NULL,	/* set on attach */
69	.todr_gettime = g2rtc_todr_gettime,
70	.todr_settime = g2rtc_todr_settime,
71};
72
73
74static inline uint32_t g2rtc_read(bus_space_tag_t, bus_space_handle_t);
75
76
77static int
78g2rtc_match(struct device *parent, struct cfdata *cf, void *aux)
79{
80	static int g2rtc_matched = 0;
81
82	if (g2rtc_matched)
83		return 0;
84
85	g2rtc_matched = 1;
86	return 1;
87}
88
89
90static void
91g2rtc_attach(struct device *parent, struct device *self, void *aux)
92{
93	struct g2rtc_softc *sc = (void *)self;
94	struct g2bus_attach_args *ga = aux;
95
96	sc->sc_bt = ga->ga_memt;
97	if (bus_space_map(sc->sc_bt, G2RTC_REG_BASE, G2RTC_REG_SIZE, 0,
98			  &sc->sc_bh) != 0)
99	{
100		printf(": unable to map registers\n");
101		return;
102	}
103	printf(": time-of-day clock\n");
104
105	g2rtc_todr_handle.cookie = sc;
106	todr_attach(&g2rtc_todr_handle);
107}
108
109
110static inline uint32_t
111g2rtc_read(bus_space_tag_t bt, bus_space_handle_t bh)
112{
113
114	return ((bus_space_read_4(bt, bh, 0) & 0xffff) << 16)
115		| (bus_space_read_4(bt, bh, 4) & 0xffff);
116}
117
118
119/*
120 * Get time-of-day and convert to `struct timeval'.
121 * Return 0 on success; an error number otherwise.
122 */
123static int
124g2rtc_todr_gettime(todr_chip_handle_t handle, volatile struct timeval *tv)
125{
126	struct g2rtc_softc *sc = handle->cookie;
127	uint32_t new, old;
128	int i;
129
130	for (old = 0;;) {
131		for (i = 0; i < 3; i++) {
132			new = g2rtc_read(sc->sc_bt, sc->sc_bh);
133			if (new != old)
134				break;
135		}
136		if (i < 3)
137			old = new;
138		else
139			break;
140	}
141
142	tv->tv_sec = new - G2RTC_OFFSET;
143	tv->tv_usec = 0;
144
145	return 0;
146}
147
148
149/*
150 * Set the time-of-day clock based on the value of the `struct timeval' arg.
151 * Return 0 on success; an error number otherwise.
152 */
153static int
154g2rtc_todr_settime(todr_chip_handle_t handle, volatile struct timeval *tv)
155{
156	struct g2rtc_softc *sc = handle->cookie;
157	uint32_t secs;
158	int i, retry;
159
160	secs = (uint32_t)tv->tv_sec + G2RTC_OFFSET;
161
162	for (retry = 0; retry < 5; retry++) {
163
164		/* Don't change the order */
165		bus_space_write_4(sc->sc_bt, sc->sc_bh, 8, 1);
166		bus_space_write_4(sc->sc_bt, sc->sc_bh, 4, secs & 0xffff);
167		bus_space_write_4(sc->sc_bt, sc->sc_bh, 0, secs >> 16);
168
169		/* verify */
170		for (i = 0; i < 3; i++)
171			if (g2rtc_read(sc->sc_bt, sc->sc_bh) == secs)
172				return 0; /* ok */
173	}
174
175	return EIO;
176
177}
178