1 /* $NetBSD: mm58167.c,v 1.17 2022/09/25 18:43:32 thorpej Exp $ */
2
3 /*
4 * Copyright (c) 2001 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Matthew Fredette.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 /*
33 * National Semiconductor MM58167 time-of-day chip subroutines.
34 */
35
36 #include <sys/cdefs.h>
37 __KERNEL_RCSID(0, "$NetBSD: mm58167.c,v 1.17 2022/09/25 18:43:32 thorpej Exp $");
38
39 #include <sys/param.h>
40 #include <sys/systm.h>
41 #include <sys/errno.h>
42 #include <sys/device.h>
43
44 #include <sys/bus.h>
45 #include <dev/clock_subr.h>
46 #include <dev/ic/mm58167var.h>
47
48 static int mm58167_gettime_ymdhms(todr_chip_handle_t, struct clock_ymdhms *);
49 static int mm58167_settime_ymdhms(todr_chip_handle_t, struct clock_ymdhms *);
50
51 /*
52 * To quote SunOS's todreg.h:
53 * "This brain damaged chip insists on keeping the time in
54 * MM/DD HH:MM:SS format, even though it doesn't know about
55 * leap years and Feb. 29, thus making it nearly worthless."
56 */
57 #define mm58167_read(sc, r) \
58 bus_space_read_1(sc->mm58167_regt, sc->mm58167_regh, sc-> r)
59 #define mm58167_write(sc, r, v) \
60 bus_space_write_1(sc->mm58167_regt, sc->mm58167_regh, sc-> r, v)
61
62 todr_chip_handle_t
mm58167_attach(struct mm58167_softc * sc)63 mm58167_attach(struct mm58167_softc *sc)
64 {
65 struct todr_chip_handle *handle;
66
67 aprint_normal(": mm58167");
68
69 handle = &sc->_mm58167_todr_handle;
70 memset(handle, 0, sizeof(*handle));
71 handle->cookie = sc;
72 handle->todr_gettime_ymdhms = mm58167_gettime_ymdhms;
73 handle->todr_settime_ymdhms = mm58167_settime_ymdhms;
74 return handle;
75 }
76
77 /*
78 * Set up the system's time, given a `reasonable' time value.
79 */
80 int
mm58167_gettime_ymdhms(todr_chip_handle_t handle,struct clock_ymdhms * dt)81 mm58167_gettime_ymdhms(todr_chip_handle_t handle, struct clock_ymdhms *dt)
82 {
83 struct mm58167_softc *sc = handle->cookie;
84 struct clock_ymdhms dt_reasonable;
85 struct timeval now;
86 int s;
87 uint8_t byte_value;
88 int leap_year, had_leap_day;
89
90 /* First, read the date out of the chip. */
91
92 /* No interrupts while we're in the chip. */
93 s = splhigh();
94
95 /* Reset the status bit: */
96 byte_value = mm58167_read(sc, mm58167_status);
97
98 /*
99 * Read the date values until we get a coherent read (one
100 * where the status stays zero, indicating no increment was
101 * rippling through while we were reading).
102 */
103 do {
104 #define _MM58167_GET(dt_f, mm_f) \
105 byte_value = mm58167_read(sc, mm_f); \
106 dt->dt_f = bcdtobin(byte_value)
107
108 _MM58167_GET(dt_mon, mm58167_mon);
109 _MM58167_GET(dt_day, mm58167_day);
110 _MM58167_GET(dt_hour, mm58167_hour);
111 _MM58167_GET(dt_min, mm58167_min);
112 _MM58167_GET(dt_sec, mm58167_sec);
113 #undef _MM58167_GET
114 } while ((mm58167_read(sc, mm58167_status) & 1) == 0);
115
116 splx(s);
117
118 /* Convert the reasonable time into a date: */
119 getmicrotime(&now);
120 clock_secs_to_ymdhms(now.tv_sec, &dt_reasonable);
121 if (dt_reasonable.dt_year == POSIX_BASE_YEAR) {
122 /*
123 * Not a reasonable year.
124 * Assume called from inittodr(9) on boot and
125 * use file system time set in inittodr(9).
126 */
127 clock_secs_to_ymdhms(handle->base_time, &dt_reasonable);
128 }
129
130 /*
131 * We need to fake a hardware year. if the hardware MM/DD
132 * HH:MM:SS date is less than the reasonable MM/DD
133 * HH:MM:SS, call it the reasonable year plus one, else call
134 * it the reasonable year.
135 */
136 if (dt->dt_mon < dt_reasonable.dt_mon ||
137 (dt->dt_mon == dt_reasonable.dt_mon &&
138 (dt->dt_day < dt_reasonable.dt_day ||
139 (dt->dt_day == dt_reasonable.dt_day &&
140 (dt->dt_hour < dt_reasonable.dt_hour ||
141 (dt->dt_hour == dt_reasonable.dt_hour &&
142 (dt->dt_min < dt_reasonable.dt_min ||
143 (dt->dt_min == dt_reasonable.dt_min &&
144 (dt->dt_sec < dt_reasonable.dt_sec))))))))) {
145 dt->dt_year = dt_reasonable.dt_year + 1;
146 } else {
147 dt->dt_year = dt_reasonable.dt_year;
148 }
149
150 /*
151 * Make a reasonable effort to see if a leap day has passed
152 * that we need to account for. This does the right thing
153 * only when the system was shut down before a leap day, and
154 * it is now after that leap day. It doesn't do the right
155 * thing when a leap day happened while the machine was last
156 * up. When that happens, the hardware clock becomes
157 * instantly wrong forever, until it gets fixed for some
158 * reason. Use NTP to deal.
159 */
160
161 /*
162 * This may have happened if the hardware says we're into
163 * March in the following year. Check that following year for
164 * a leap day.
165 */
166 if (dt->dt_year > dt_reasonable.dt_year &&
167 dt->dt_mon >= 3) {
168 leap_year = dt->dt_year;
169 }
170
171 /*
172 * This may have happened if the hardware says we're in the
173 * following year, and the system was shut down before March
174 * the previous year. check that previous year for a leap
175 * day.
176 */
177 else if (dt->dt_year > dt_reasonable.dt_year &&
178 dt_reasonable.dt_mon < 3) {
179 leap_year = dt_reasonable.dt_year;
180 }
181
182 /*
183 * This may have happened if the hardware says we're in the
184 * same year, but we weren't to March before, and we're in or
185 * past March now. Check this year for a leap day.
186 */
187 else if (dt->dt_year == dt_reasonable.dt_year
188 && dt_reasonable.dt_mon < 3
189 && dt->dt_mon >= 3) {
190 leap_year = dt_reasonable.dt_year;
191 }
192
193 /*
194 * Otherwise, no leap year to check.
195 */
196 else {
197 leap_year = 0;
198 }
199
200 /* Do the real leap day check. */
201 had_leap_day = 0;
202 if (leap_year > 0) {
203 if ((leap_year & 3) == 0) {
204 had_leap_day = 1;
205 if ((leap_year % 100) == 0) {
206 had_leap_day = 0;
207 if ((leap_year % 400) == 0)
208 had_leap_day = 1;
209 }
210 }
211 }
212
213 /*
214 * If we had a leap day, adjust the value we will return, and
215 * also update the hardware clock.
216 */
217 /*
218 * XXX - Since this update just writes back a corrected
219 * version of what we read out above, we lose whatever
220 * amount of time the clock has advanced since that read.
221 * Use NTP to deal.
222 */
223 if (had_leap_day) {
224 mm58167_settime_ymdhms(handle, dt);
225 }
226
227 return 0;
228 }
229
230 int
mm58167_settime_ymdhms(todr_chip_handle_t handle,struct clock_ymdhms * dt)231 mm58167_settime_ymdhms(todr_chip_handle_t handle, struct clock_ymdhms *dt)
232 {
233 struct mm58167_softc *sc = handle->cookie;
234 int s;
235 uint8_t byte_value;
236
237 /* No interrupts while we're in the chip. */
238 s = splhigh();
239
240 /*
241 * Issue a GO command to reset everything less significant
242 * than the minutes to zero.
243 */
244 mm58167_write(sc, mm58167_go, 0xFF);
245
246 /* Load everything. */
247 #define _MM58167_PUT(dt_f, mm_f) \
248 byte_value = bintobcd(dt->dt_f); \
249 mm58167_write(sc, mm_f, byte_value)
250
251 _MM58167_PUT(dt_mon, mm58167_mon);
252 _MM58167_PUT(dt_day, mm58167_day);
253 _MM58167_PUT(dt_hour, mm58167_hour);
254 _MM58167_PUT(dt_min, mm58167_min);
255 _MM58167_PUT(dt_sec, mm58167_sec);
256 #undef _MM58167_PUT
257
258 splx(s);
259 return 0;
260 }
261