xref: /openbmc/linux/arch/m68k/atari/time.c (revision 85250a24) 
1 /*
2  * linux/arch/m68k/atari/time.c
3  *
4  * Atari time and real time clock stuff
5  *
6  * Assembled of parts of former atari/config.c 97-12-18 by Roman Hodek
7  *
8  * This file is subject to the terms and conditions of the GNU General Public
9  * License.  See the file COPYING in the main directory of this archive
10  * for more details.
11  */
12 
13 #include <linux/types.h>
14 #include <linux/mc146818rtc.h>
15 #include <linux/interrupt.h>
16 #include <linux/init.h>
17 #include <linux/rtc.h>
18 #include <linux/bcd.h>
19 #include <linux/clocksource.h>
20 #include <linux/delay.h>
21 #include <linux/export.h>
22 
23 #include <asm/atariints.h>
24 #include <asm/machdep.h>
25 
26 DEFINE_SPINLOCK(rtc_lock);
27 EXPORT_SYMBOL_GPL(rtc_lock);
28 
29 static u64 atari_read_clk(struct clocksource *cs);
30 
31 static struct clocksource atari_clk = {
32 	.name   = "mfp",
33 	.rating = 100,
34 	.read   = atari_read_clk,
35 	.mask   = CLOCKSOURCE_MASK(32),
36 	.flags  = CLOCK_SOURCE_IS_CONTINUOUS,
37 };
38 
39 static u32 clk_total;
40 static u8 last_timer_count;
41 
42 static irqreturn_t mfp_timer_c_handler(int irq, void *dev_id)
43 {
44 	unsigned long flags;
45 
46 	local_irq_save(flags);
47 	do {
48 		last_timer_count = st_mfp.tim_dt_c;
49 	} while (last_timer_count == 1);
50 	clk_total += INT_TICKS;
51 	legacy_timer_tick(1);
52 	timer_heartbeat();
53 	local_irq_restore(flags);
54 
55 	return IRQ_HANDLED;
56 }
57 
58 void __init
59 atari_sched_init(void)
60 {
61     /* set Timer C data Register */
62     st_mfp.tim_dt_c = INT_TICKS;
63     /* start timer C, div = 1:100 */
64     st_mfp.tim_ct_cd = (st_mfp.tim_ct_cd & 15) | 0x60;
65     /* install interrupt service routine for MFP Timer C */
66     if (request_irq(IRQ_MFP_TIMC, mfp_timer_c_handler, IRQF_TIMER, "timer",
67                     NULL))
68 	pr_err("Couldn't register timer interrupt\n");
69 
70     clocksource_register_hz(&atari_clk, INT_CLK);
71 }
72 
73 /* ++andreas: gettimeoffset fixed to check for pending interrupt */
74 
75 static u64 atari_read_clk(struct clocksource *cs)
76 {
77 	unsigned long flags;
78 	u8 count;
79 	u32 ticks;
80 
81 	local_irq_save(flags);
82 	/* Ensure that the count is monotonically decreasing, even though
83 	 * the result may briefly stop changing after counter wrap-around.
84 	 */
85 	count = min(st_mfp.tim_dt_c, last_timer_count);
86 	last_timer_count = count;
87 
88 	ticks = INT_TICKS - count;
89 	ticks += clk_total;
90 	local_irq_restore(flags);
91 
92 	return ticks;
93 }
94 
95 
96 static void mste_read(struct MSTE_RTC *val)
97 {
98 #define COPY(v) val->v=(mste_rtc.v & 0xf)
99 	do {
100 		COPY(sec_ones) ; COPY(sec_tens) ; COPY(min_ones) ;
101 		COPY(min_tens) ; COPY(hr_ones) ; COPY(hr_tens) ;
102 		COPY(weekday) ; COPY(day_ones) ; COPY(day_tens) ;
103 		COPY(mon_ones) ; COPY(mon_tens) ; COPY(year_ones) ;
104 		COPY(year_tens) ;
105 	/* prevent from reading the clock while it changed */
106 	} while (val->sec_ones != (mste_rtc.sec_ones & 0xf));
107 #undef COPY
108 }
109 
110 static void mste_write(struct MSTE_RTC *val)
111 {
112 #define COPY(v) mste_rtc.v=val->v
113 	do {
114 		COPY(sec_ones) ; COPY(sec_tens) ; COPY(min_ones) ;
115 		COPY(min_tens) ; COPY(hr_ones) ; COPY(hr_tens) ;
116 		COPY(weekday) ; COPY(day_ones) ; COPY(day_tens) ;
117 		COPY(mon_ones) ; COPY(mon_tens) ; COPY(year_ones) ;
118 		COPY(year_tens) ;
119 	/* prevent from writing the clock while it changed */
120 	} while (val->sec_ones != (mste_rtc.sec_ones & 0xf));
121 #undef COPY
122 }
123 
124 #define	RTC_READ(reg)				\
125     ({	unsigned char	__val;			\
126 		(void) atari_writeb(reg,&tt_rtc.regsel);	\
127 		__val = tt_rtc.data;		\
128 		__val;				\
129 	})
130 
131 #define	RTC_WRITE(reg,val)			\
132     do {					\
133 		atari_writeb(reg,&tt_rtc.regsel);	\
134 		tt_rtc.data = (val);		\
135 	} while(0)
136 
137 
138 #define HWCLK_POLL_INTERVAL	5
139 
140 int atari_mste_hwclk( int op, struct rtc_time *t )
141 {
142     int hour, year;
143     int hr24=0;
144     struct MSTE_RTC val;
145 
146     mste_rtc.mode=(mste_rtc.mode | 1);
147     hr24=mste_rtc.mon_tens & 1;
148     mste_rtc.mode=(mste_rtc.mode & ~1);
149 
150     if (op) {
151         /* write: prepare values */
152 
153         val.sec_ones = t->tm_sec % 10;
154         val.sec_tens = t->tm_sec / 10;
155         val.min_ones = t->tm_min % 10;
156         val.min_tens = t->tm_min / 10;
157         hour = t->tm_hour;
158         if (!hr24) {
159 	    if (hour > 11)
160 		hour += 20 - 12;
161 	    if (hour == 0 || hour == 20)
162 		hour += 12;
163         }
164         val.hr_ones = hour % 10;
165         val.hr_tens = hour / 10;
166         val.day_ones = t->tm_mday % 10;
167         val.day_tens = t->tm_mday / 10;
168         val.mon_ones = (t->tm_mon+1) % 10;
169         val.mon_tens = (t->tm_mon+1) / 10;
170         year = t->tm_year - 80;
171         val.year_ones = year % 10;
172         val.year_tens = year / 10;
173         val.weekday = t->tm_wday;
174         mste_write(&val);
175         mste_rtc.mode=(mste_rtc.mode | 1);
176         val.year_ones = (year % 4);	/* leap year register */
177         mste_rtc.mode=(mste_rtc.mode & ~1);
178     }
179     else {
180         mste_read(&val);
181         t->tm_sec = val.sec_ones + val.sec_tens * 10;
182         t->tm_min = val.min_ones + val.min_tens * 10;
183         hour = val.hr_ones + val.hr_tens * 10;
184 	if (!hr24) {
185 	    if (hour == 12 || hour == 12 + 20)
186 		hour -= 12;
187 	    if (hour >= 20)
188                 hour += 12 - 20;
189         }
190 	t->tm_hour = hour;
191 	t->tm_mday = val.day_ones + val.day_tens * 10;
192         t->tm_mon  = val.mon_ones + val.mon_tens * 10 - 1;
193         t->tm_year = val.year_ones + val.year_tens * 10 + 80;
194         t->tm_wday = val.weekday;
195     }
196     return 0;
197 }
198 
199 int atari_tt_hwclk( int op, struct rtc_time *t )
200 {
201     int sec=0, min=0, hour=0, day=0, mon=0, year=0, wday=0;
202     unsigned long	flags;
203     unsigned char	ctrl;
204     int pm = 0;
205 
206     ctrl = RTC_READ(RTC_CONTROL); /* control registers are
207                                    * independent from the UIP */
208 
209     if (op) {
210         /* write: prepare values */
211 
212         sec  = t->tm_sec;
213         min  = t->tm_min;
214         hour = t->tm_hour;
215         day  = t->tm_mday;
216         mon  = t->tm_mon + 1;
217         year = t->tm_year - atari_rtc_year_offset;
218         wday = t->tm_wday + (t->tm_wday >= 0);
219 
220         if (!(ctrl & RTC_24H)) {
221 	    if (hour > 11) {
222 		pm = 0x80;
223 		if (hour != 12)
224 		    hour -= 12;
225 	    }
226 	    else if (hour == 0)
227 		hour = 12;
228         }
229 
230         if (!(ctrl & RTC_DM_BINARY)) {
231 	    sec = bin2bcd(sec);
232 	    min = bin2bcd(min);
233 	    hour = bin2bcd(hour);
234 	    day = bin2bcd(day);
235 	    mon = bin2bcd(mon);
236 	    year = bin2bcd(year);
237 	    if (wday >= 0)
238 		wday = bin2bcd(wday);
239         }
240     }
241 
242     /* Reading/writing the clock registers is a bit critical due to
243      * the regular update cycle of the RTC. While an update is in
244      * progress, registers 0..9 shouldn't be touched.
245      * The problem is solved like that: If an update is currently in
246      * progress (the UIP bit is set), the process sleeps for a while
247      * (50ms). This really should be enough, since the update cycle
248      * normally needs 2 ms.
249      * If the UIP bit reads as 0, we have at least 244 usecs until the
250      * update starts. This should be enough... But to be sure,
251      * additionally the RTC_SET bit is set to prevent an update cycle.
252      */
253 
254     while( RTC_READ(RTC_FREQ_SELECT) & RTC_UIP ) {
255 	if (in_atomic() || irqs_disabled())
256 	    mdelay(1);
257 	else
258 	    schedule_timeout_interruptible(HWCLK_POLL_INTERVAL);
259     }
260 
261     local_irq_save(flags);
262     RTC_WRITE( RTC_CONTROL, ctrl | RTC_SET );
263     if (!op) {
264         sec  = RTC_READ( RTC_SECONDS );
265         min  = RTC_READ( RTC_MINUTES );
266         hour = RTC_READ( RTC_HOURS );
267         day  = RTC_READ( RTC_DAY_OF_MONTH );
268         mon  = RTC_READ( RTC_MONTH );
269         year = RTC_READ( RTC_YEAR );
270         wday = RTC_READ( RTC_DAY_OF_WEEK );
271     }
272     else {
273         RTC_WRITE( RTC_SECONDS, sec );
274         RTC_WRITE( RTC_MINUTES, min );
275         RTC_WRITE( RTC_HOURS, hour + pm);
276         RTC_WRITE( RTC_DAY_OF_MONTH, day );
277         RTC_WRITE( RTC_MONTH, mon );
278         RTC_WRITE( RTC_YEAR, year );
279         if (wday >= 0) RTC_WRITE( RTC_DAY_OF_WEEK, wday );
280     }
281     RTC_WRITE( RTC_CONTROL, ctrl & ~RTC_SET );
282     local_irq_restore(flags);
283 
284     if (!op) {
285         /* read: adjust values */
286 
287         if (hour & 0x80) {
288 	    hour &= ~0x80;
289 	    pm = 1;
290 	}
291 
292 	if (!(ctrl & RTC_DM_BINARY)) {
293 	    sec = bcd2bin(sec);
294 	    min = bcd2bin(min);
295 	    hour = bcd2bin(hour);
296 	    day = bcd2bin(day);
297 	    mon = bcd2bin(mon);
298 	    year = bcd2bin(year);
299 	    wday = bcd2bin(wday);
300         }
301 
302         if (!(ctrl & RTC_24H)) {
303 	    if (!pm && hour == 12)
304 		hour = 0;
305 	    else if (pm && hour != 12)
306 		hour += 12;
307         }
308 
309         t->tm_sec  = sec;
310         t->tm_min  = min;
311         t->tm_hour = hour;
312         t->tm_mday = day;
313         t->tm_mon  = mon - 1;
314         t->tm_year = year + atari_rtc_year_offset;
315         t->tm_wday = wday - 1;
316     }
317 
318     return( 0 );
319 }
320