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1 /*
2  *  arch/arm/mach-footbridge/include/mach/time.h
3  *
4  *  Copyright (C) 1998 Russell King.
5  *  Copyright (C) 1998 Phil Blundell
6  *
7  * CATS has a real-time clock, though the evaluation board doesn't.
8  *
9  * Changelog:
10  *  21-Mar-1998 RMK     Created
11  *  27-Aug-1998 PJB     CATS support
12  *  28-Dec-1998 APH     Made leds optional
13  *  20-Jan-1999 RMK     Started merge of EBSA285, CATS and NetWinder
14  *  16-Mar-1999 RMK     More support for EBSA285-like machines with RTCs in
15  */
16
17 #define RTC_PORT(x)             (rtc_base+(x))
18 #define RTC_ALWAYS_BCD          0
19
20 #include <linux/timex.h>
21 #include <linux/init.h>
22 #include <linux/sched.h>
23 #include <linux/mc146818rtc.h>
24 #include <linux/bcd.h>
25
26 #include <mach/hardware.h>
27 #include <asm/io.h>
28
29 #include <asm/mach/time.h>
30 #include "common.h"
31
32 static int rtc_base;
33
34 static unsigned long __init get_isa_cmos_time(void)
35 {
36         unsigned int year, mon, day, hour, min, sec;
37
38         // check to see if the RTC makes sense.....
39         if ((CMOS_READ(RTC_VALID) & RTC_VRT) == 0)
40                 return mktime(1970, 1, 1, 0, 0, 0);
41
42         do {
43                 sec  = CMOS_READ(RTC_SECONDS);
44                 min  = CMOS_READ(RTC_MINUTES);
45                 hour = CMOS_READ(RTC_HOURS);
46                 day  = CMOS_READ(RTC_DAY_OF_MONTH);
47                 mon  = CMOS_READ(RTC_MONTH);
48                 year = CMOS_READ(RTC_YEAR);
49         } while (sec != CMOS_READ(RTC_SECONDS));
50
51         if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
52                 sec = bcd2bin(sec);
53                 min = bcd2bin(min);
54                 hour = bcd2bin(hour);
55                 day = bcd2bin(day);
56                 mon = bcd2bin(mon);
57                 year = bcd2bin(year);
58         }
59         if ((year += 1900) < 1970)
60                 year += 100;
61         return mktime(year, mon, day, hour, min, sec);
62 }
63
64 static int set_isa_cmos_time(void)
65 {
66         int retval = 0;
67         int real_seconds, real_minutes, cmos_minutes;
68         unsigned char save_control, save_freq_select;
69         unsigned long nowtime = xtime.tv_sec;
70
71         save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being set */
72         CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
73
74         save_freq_select = CMOS_READ(RTC_FREQ_SELECT); /* stop and reset prescaler */
75         CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
76
77         cmos_minutes = CMOS_READ(RTC_MINUTES);
78         if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
79                 cmos_minutes = bcd2bin(cmos_minutes);
80
81         /*
82          * since we're only adjusting minutes and seconds,
83          * don't interfere with hour overflow. This avoids
84          * messing with unknown time zones but requires your
85          * RTC not to be off by more than 15 minutes
86          */
87         real_seconds = nowtime % 60;
88         real_minutes = nowtime / 60;
89         if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
90                 real_minutes += 30;             /* correct for half hour time zone */
91         real_minutes %= 60;
92
93         if (abs(real_minutes - cmos_minutes) < 30) {
94                 if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
95                         real_seconds = bin2bcd(real_seconds);
96                         real_minutes = bin2bcd(real_minutes);
97                 }
98                 CMOS_WRITE(real_seconds,RTC_SECONDS);
99                 CMOS_WRITE(real_minutes,RTC_MINUTES);
100         } else
101                 retval = -1;
102
103         /* The following flags have to be released exactly in this order,
104          * otherwise the DS12887 (popular MC146818A clone with integrated
105          * battery and quartz) will not reset the oscillator and will not
106          * update precisely 500 ms later. You won't find this mentioned in
107          * the Dallas Semiconductor data sheets, but who believes data
108          * sheets anyway ...                           -- Markus Kuhn
109          */
110         CMOS_WRITE(save_control, RTC_CONTROL);
111         CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
112
113         return retval;
114 }
115
116 void __init isa_rtc_init(void)
117 {
118         if (machine_is_personal_server())
119                 /*
120                  * Add-in 21285s shouldn't access the RTC
121                  */
122                 rtc_base = 0;
123         else
124                 rtc_base = 0x70;
125
126         if (rtc_base) {
127                 int reg_d, reg_b;
128
129                 /*
130                  * Probe for the RTC.
131                  */
132                 reg_d = CMOS_READ(RTC_REG_D);
133
134                 /*
135                  * make sure the divider is set
136                  */
137                 CMOS_WRITE(RTC_REF_CLCK_32KHZ, RTC_REG_A);
138
139                 /*
140                  * Set control reg B
141                  *   (24 hour mode, update enabled)
142                  */
143                 reg_b = CMOS_READ(RTC_REG_B) & 0x7f;
144                 reg_b |= 2;
145                 CMOS_WRITE(reg_b, RTC_REG_B);
146
147                 if ((CMOS_READ(RTC_REG_A) & 0x7f) == RTC_REF_CLCK_32KHZ &&
148                     CMOS_READ(RTC_REG_B) == reg_b) {
149                         struct timespec tv;
150
151                         /*
152                          * We have a RTC.  Check the battery
153                          */
154                         if ((reg_d & 0x80) == 0)
155                                 printk(KERN_WARNING "RTC: *** warning: CMOS battery bad\n");
156
157                         tv.tv_nsec = 0;
158                         tv.tv_sec = get_isa_cmos_time();
159                         do_settimeofday(&tv);
160                         set_rtc = set_isa_cmos_time;
161                 } else
162                         rtc_base = 0;
163         }
164 }