g2rtc.c revision 1.2 
1/* $NetBSD: g2rtc.c,v 1.2 2008/01/06 10:33:24 he 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 * 3. All advertising materials mentioning features or use of this software
16 *    must display the following acknowledgement:
17 *        This product includes software developed by the NetBSD
18 *        Foundation, Inc. and its contributors.
19 * 4. Neither the name of The NetBSD Foundation nor the names of its
20 *    contributors may be used to endorse or promote products derived
21 *    from this software without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
24 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
25 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
26 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
27 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
28 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
29 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
30 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
31 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
32 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
33 * POSSIBILITY OF SUCH DAMAGE.
34 */
35
36#include <sys/cdefs.h>
37__KERNEL_RCSID(0, "$NetBSD: g2rtc.c,v 1.2 2008/01/06 10:33:24 he Exp $");
38
39#include <sys/param.h>
40#include <sys/systm.h>
41#include <sys/device.h>
42
43#include <dev/clock_subr.h>
44
45#include <machine/bus.h>
46#include <dreamcast/dev/g2/g2busvar.h>
47
48
49#define G2RTC_REG_BASE	0x00710000
50#define G2RTC_REG_SIZE	12
51
52/* Offset by 20 years, 5 of them are leap */
53#define G2RTC_OFFSET	(20 * SECYR + 5 * SECDAY)
54
55struct g2rtc_softc {
56	struct device sc_dev;
57
58	bus_space_tag_t sc_bt;
59	bus_space_handle_t sc_bh;
60};
61
62/* autoconf glue */
63static int g2rtc_match(struct device *, struct cfdata *, void *);
64static void g2rtc_attach(struct device *, struct device *, void *);
65
66CFATTACH_DECL(g2rtc, sizeof(struct g2rtc_softc),
67	      g2rtc_match, g2rtc_attach, NULL, NULL);
68
69
70/* todr(9) methods */
71static int g2rtc_todr_gettime(todr_chip_handle_t, volatile struct timeval *);
72static int g2rtc_todr_settime(todr_chip_handle_t, volatile struct timeval *);
73
74static struct todr_chip_handle g2rtc_todr_handle = {
75	.cookie       = NULL,	/* set on attach */
76	.todr_gettime = g2rtc_todr_gettime,
77	.todr_settime = g2rtc_todr_settime,
78};
79
80
81static inline uint32_t g2rtc_read(bus_space_tag_t, bus_space_handle_t);
82
83
84static int
85g2rtc_match(struct device *parent, struct cfdata *cf, void *aux)
86{
87	static int g2rtc_matched = 0;
88
89	if (g2rtc_matched)
90		return 0;
91
92	g2rtc_matched = 1;
93	return 1;
94}
95
96
97static void
98g2rtc_attach(struct device *parent, struct device *self, void *aux)
99{
100	struct g2rtc_softc *sc = (void *)self;
101	struct g2bus_attach_args *ga = aux;
102
103	sc->sc_bt = ga->ga_memt;
104	if (bus_space_map(sc->sc_bt, G2RTC_REG_BASE, G2RTC_REG_SIZE, 0,
105			  &sc->sc_bh) != 0)
106	{
107		printf(": unable to map registers\n");
108		return;
109	}
110	printf(": time-of-day clock\n");
111
112	g2rtc_todr_handle.cookie = sc;
113	todr_attach(&g2rtc_todr_handle);
114}
115
116
117static inline uint32_t
118g2rtc_read(bus_space_tag_t bt, bus_space_handle_t bh)
119{
120
121	return ((bus_space_read_4(bt, bh, 0) & 0xffff) << 16)
122		| (bus_space_read_4(bt, bh, 4) & 0xffff);
123}
124
125
126/*
127 * Get time-of-day and convert to `struct timeval'.
128 * Return 0 on success; an error number otherwise.
129 */
130static int
131g2rtc_todr_gettime(todr_chip_handle_t handle, volatile struct timeval *tv)
132{
133	struct g2rtc_softc *sc = handle->cookie;
134	uint32_t new, old;
135	int i;
136
137	for (old = 0;;) {
138		for (i = 0; i < 3; i++) {
139			new = g2rtc_read(sc->sc_bt, sc->sc_bh);
140			if (new != old)
141				break;
142		}
143		if (i < 3)
144			old = new;
145		else
146			break;
147	}
148
149	tv->tv_sec = new - G2RTC_OFFSET;
150	tv->tv_usec = 0;
151
152	return 0;
153}
154
155
156/*
157 * Set the time-of-day clock based on the value of the `struct timeval' arg.
158 * Return 0 on success; an error number otherwise.
159 */
160static int
161g2rtc_todr_settime(todr_chip_handle_t handle, volatile struct timeval *tv)
162{
163	struct g2rtc_softc *sc = handle->cookie;
164	uint32_t secs;
165	int i, retry;
166
167	secs = (uint32_t)tv->tv_sec + G2RTC_OFFSET;
168
169	for (retry = 0; retry < 5; retry++) {
170
171		/* Don't change the order */
172		bus_space_write_4(sc->sc_bt, sc->sc_bh, 8, 1);
173		bus_space_write_4(sc->sc_bt, sc->sc_bh, 4, secs & 0xffff);
174		bus_space_write_4(sc->sc_bt, sc->sc_bh, 0, secs >> 16);
175
176		/* verify */
177		for (i = 0; i < 3; i++)
178			if (g2rtc_read(sc->sc_bt, sc->sc_bh) == secs)
179				return 0; /* ok */
180	}
181
182	return EIO;
183
184}
185