LXR linux/drivers/rtc/rtc-mc146818-lib.c

   1#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);
 199