blob: 2f1772a358ca50342d4375de3e69f2fba451ceaf [file] [log] [blame]
Arnd Bergmannd6faca42016-06-01 16:46:23 +02001#include <linux/bcd.h>
2#include <linux/delay.h>
3#include <linux/export.h>
4#include <linux/mc146818rtc.h>
5
6#ifdef CONFIG_ACPI
7#include <linux/acpi.h>
8#endif
9
10/*
11 * Returns true if a clock update is in progress
12 */
13static inline unsigned char mc146818_is_updating(void)
14{
15 unsigned char uip;
16 unsigned long flags;
17
18 spin_lock_irqsave(&rtc_lock, flags);
19 uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
20 spin_unlock_irqrestore(&rtc_lock, flags);
21 return uip;
22}
23
24unsigned int mc146818_get_time(struct rtc_time *time)
25{
26 unsigned char ctrl;
27 unsigned long flags;
28 unsigned char century = 0;
29
30#ifdef CONFIG_MACH_DECSTATION
31 unsigned int real_year;
32#endif
33
34 /*
35 * read RTC once any update in progress is done. The update
36 * can take just over 2ms. We wait 20ms. There is no need to
37 * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
38 * If you need to know *exactly* when a second has started, enable
39 * periodic update complete interrupts, (via ioctl) and then
40 * immediately read /dev/rtc which will block until you get the IRQ.
41 * Once the read clears, read the RTC time (again via ioctl). Easy.
42 */
43 if (mc146818_is_updating())
44 mdelay(20);
45
46 /*
47 * Only the values that we read from the RTC are set. We leave
48 * tm_wday, tm_yday and tm_isdst untouched. Even though the
49 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
50 * by the RTC when initially set to a non-zero value.
51 */
52 spin_lock_irqsave(&rtc_lock, flags);
53 time->tm_sec = CMOS_READ(RTC_SECONDS);
54 time->tm_min = CMOS_READ(RTC_MINUTES);
55 time->tm_hour = CMOS_READ(RTC_HOURS);
56 time->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
57 time->tm_mon = CMOS_READ(RTC_MONTH);
58 time->tm_year = CMOS_READ(RTC_YEAR);
59#ifdef CONFIG_MACH_DECSTATION
60 real_year = CMOS_READ(RTC_DEC_YEAR);
61#endif
62#ifdef CONFIG_ACPI
63 if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
64 acpi_gbl_FADT.century)
65 century = CMOS_READ(acpi_gbl_FADT.century);
66#endif
67 ctrl = CMOS_READ(RTC_CONTROL);
68 spin_unlock_irqrestore(&rtc_lock, flags);
69
70 if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
71 {
72 time->tm_sec = bcd2bin(time->tm_sec);
73 time->tm_min = bcd2bin(time->tm_min);
74 time->tm_hour = bcd2bin(time->tm_hour);
75 time->tm_mday = bcd2bin(time->tm_mday);
76 time->tm_mon = bcd2bin(time->tm_mon);
77 time->tm_year = bcd2bin(time->tm_year);
78 century = bcd2bin(century);
79 }
80
81#ifdef CONFIG_MACH_DECSTATION
82 time->tm_year += real_year - 72;
83#endif
84
85 if (century)
86 time->tm_year += (century - 19) * 100;
87
88 /*
89 * Account for differences between how the RTC uses the values
90 * and how they are defined in a struct rtc_time;
91 */
92 if (time->tm_year <= 69)
93 time->tm_year += 100;
94
95 time->tm_mon--;
96
97 return RTC_24H;
98}
99EXPORT_SYMBOL_GPL(mc146818_get_time);
100
101/* Set the current date and time in the real time clock. */
102int mc146818_set_time(struct rtc_time *time)
103{
104 unsigned long flags;
105 unsigned char mon, day, hrs, min, sec;
106 unsigned char save_control, save_freq_select;
107 unsigned int yrs;
108#ifdef CONFIG_MACH_DECSTATION
109 unsigned int real_yrs, leap_yr;
110#endif
111 unsigned char century = 0;
112
113 yrs = time->tm_year;
114 mon = time->tm_mon + 1; /* tm_mon starts at zero */
115 day = time->tm_mday;
116 hrs = time->tm_hour;
117 min = time->tm_min;
118 sec = time->tm_sec;
119
120 if (yrs > 255) /* They are unsigned */
121 return -EINVAL;
122
123 spin_lock_irqsave(&rtc_lock, flags);
124#ifdef CONFIG_MACH_DECSTATION
125 real_yrs = yrs;
126 leap_yr = ((!((yrs + 1900) % 4) && ((yrs + 1900) % 100)) ||
127 !((yrs + 1900) % 400));
128 yrs = 72;
129
130 /*
131 * We want to keep the year set to 73 until March
132 * for non-leap years, so that Feb, 29th is handled
133 * correctly.
134 */
135 if (!leap_yr && mon < 3) {
136 real_yrs--;
137 yrs = 73;
138 }
139#endif
140
141#ifdef CONFIG_ACPI
142 if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
143 acpi_gbl_FADT.century) {
144 century = (yrs + 1900) / 100;
145 yrs %= 100;
146 }
147#endif
148
149 /* These limits and adjustments are independent of
150 * whether the chip is in binary mode or not.
151 */
152 if (yrs > 169) {
153 spin_unlock_irqrestore(&rtc_lock, flags);
154 return -EINVAL;
155 }
156
157 if (yrs >= 100)
158 yrs -= 100;
159
160 if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)
161 || RTC_ALWAYS_BCD) {
162 sec = bin2bcd(sec);
163 min = bin2bcd(min);
164 hrs = bin2bcd(hrs);
165 day = bin2bcd(day);
166 mon = bin2bcd(mon);
167 yrs = bin2bcd(yrs);
168 century = bin2bcd(century);
169 }
170
171 save_control = CMOS_READ(RTC_CONTROL);
172 CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
173 save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
174 CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
175
176#ifdef CONFIG_MACH_DECSTATION
177 CMOS_WRITE(real_yrs, RTC_DEC_YEAR);
178#endif
179 CMOS_WRITE(yrs, RTC_YEAR);
180 CMOS_WRITE(mon, RTC_MONTH);
181 CMOS_WRITE(day, RTC_DAY_OF_MONTH);
182 CMOS_WRITE(hrs, RTC_HOURS);
183 CMOS_WRITE(min, RTC_MINUTES);
184 CMOS_WRITE(sec, RTC_SECONDS);
185#ifdef CONFIG_ACPI
186 if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
187 acpi_gbl_FADT.century)
188 CMOS_WRITE(century, acpi_gbl_FADT.century);
189#endif
190
191 CMOS_WRITE(save_control, RTC_CONTROL);
192 CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
193
194 spin_unlock_irqrestore(&rtc_lock, flags);
195
196 return 0;
197}
198EXPORT_SYMBOL_GPL(mc146818_set_time);