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218 lines
5.4 KiB
218 lines
5.4 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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#include <linux/bcd.h> |
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#include <linux/delay.h> |
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#include <linux/export.h> |
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#include <linux/mc146818rtc.h> |
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#ifdef CONFIG_ACPI |
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#include <linux/acpi.h> |
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#endif |
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unsigned int mc146818_get_time(struct rtc_time *time) |
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{ |
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unsigned char ctrl; |
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unsigned long flags; |
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unsigned char century = 0; |
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bool retry; |
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#ifdef CONFIG_MACH_DECSTATION |
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unsigned int real_year; |
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#endif |
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again: |
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spin_lock_irqsave(&rtc_lock, flags); |
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/* Ensure that the RTC is accessible. Bit 6 must be 0! */ |
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if (WARN_ON_ONCE((CMOS_READ(RTC_VALID) & 0x40) != 0)) { |
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spin_unlock_irqrestore(&rtc_lock, flags); |
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memset(time, 0xff, sizeof(*time)); |
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return 0; |
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} |
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/* |
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* Check whether there is an update in progress during which the |
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* readout is unspecified. The maximum update time is ~2ms. Poll |
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* every msec for completion. |
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* |
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* Store the second value before checking UIP so a long lasting NMI |
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* which happens to hit after the UIP check cannot make an update |
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* cycle invisible. |
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*/ |
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time->tm_sec = CMOS_READ(RTC_SECONDS); |
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if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP) { |
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spin_unlock_irqrestore(&rtc_lock, flags); |
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mdelay(1); |
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goto again; |
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} |
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/* Revalidate the above readout */ |
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if (time->tm_sec != CMOS_READ(RTC_SECONDS)) { |
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spin_unlock_irqrestore(&rtc_lock, flags); |
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goto again; |
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} |
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/* |
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* Only the values that we read from the RTC are set. We leave |
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* tm_wday, tm_yday and tm_isdst untouched. Even though the |
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* RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated |
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* by the RTC when initially set to a non-zero value. |
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*/ |
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time->tm_min = CMOS_READ(RTC_MINUTES); |
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time->tm_hour = CMOS_READ(RTC_HOURS); |
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time->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH); |
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time->tm_mon = CMOS_READ(RTC_MONTH); |
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time->tm_year = CMOS_READ(RTC_YEAR); |
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#ifdef CONFIG_MACH_DECSTATION |
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real_year = CMOS_READ(RTC_DEC_YEAR); |
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#endif |
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#ifdef CONFIG_ACPI |
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if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID && |
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acpi_gbl_FADT.century) |
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century = CMOS_READ(acpi_gbl_FADT.century); |
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#endif |
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ctrl = CMOS_READ(RTC_CONTROL); |
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/* |
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* Check for the UIP bit again. If it is set now then |
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* the above values may contain garbage. |
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*/ |
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retry = CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP; |
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/* |
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* A NMI might have interrupted the above sequence so check whether |
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* the seconds value has changed which indicates that the NMI took |
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* longer than the UIP bit was set. Unlikely, but possible and |
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* there is also virt... |
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*/ |
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retry |= time->tm_sec != CMOS_READ(RTC_SECONDS); |
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spin_unlock_irqrestore(&rtc_lock, flags); |
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if (retry) |
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goto again; |
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if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD) |
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{ |
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time->tm_sec = bcd2bin(time->tm_sec); |
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time->tm_min = bcd2bin(time->tm_min); |
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time->tm_hour = bcd2bin(time->tm_hour); |
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time->tm_mday = bcd2bin(time->tm_mday); |
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time->tm_mon = bcd2bin(time->tm_mon); |
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time->tm_year = bcd2bin(time->tm_year); |
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century = bcd2bin(century); |
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} |
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#ifdef CONFIG_MACH_DECSTATION |
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time->tm_year += real_year - 72; |
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#endif |
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if (century > 20) |
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time->tm_year += (century - 19) * 100; |
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/* |
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* Account for differences between how the RTC uses the values |
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* and how they are defined in a struct rtc_time; |
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*/ |
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if (time->tm_year <= 69) |
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time->tm_year += 100; |
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time->tm_mon--; |
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return RTC_24H; |
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} |
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EXPORT_SYMBOL_GPL(mc146818_get_time); |
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/* Set the current date and time in the real time clock. */ |
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int mc146818_set_time(struct rtc_time *time) |
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{ |
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unsigned long flags; |
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unsigned char mon, day, hrs, min, sec; |
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unsigned char save_control, save_freq_select; |
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unsigned int yrs; |
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#ifdef CONFIG_MACH_DECSTATION |
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unsigned int real_yrs, leap_yr; |
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#endif |
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unsigned char century = 0; |
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yrs = time->tm_year; |
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mon = time->tm_mon + 1; /* tm_mon starts at zero */ |
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day = time->tm_mday; |
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hrs = time->tm_hour; |
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min = time->tm_min; |
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sec = time->tm_sec; |
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if (yrs > 255) /* They are unsigned */ |
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return -EINVAL; |
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#ifdef CONFIG_MACH_DECSTATION |
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real_yrs = yrs; |
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leap_yr = ((!((yrs + 1900) % 4) && ((yrs + 1900) % 100)) || |
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!((yrs + 1900) % 400)); |
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yrs = 72; |
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/* |
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* We want to keep the year set to 73 until March |
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* for non-leap years, so that Feb, 29th is handled |
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* correctly. |
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*/ |
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if (!leap_yr && mon < 3) { |
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real_yrs--; |
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yrs = 73; |
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} |
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#endif |
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#ifdef CONFIG_ACPI |
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if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID && |
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acpi_gbl_FADT.century) { |
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century = (yrs + 1900) / 100; |
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yrs %= 100; |
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} |
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#endif |
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/* These limits and adjustments are independent of |
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* whether the chip is in binary mode or not. |
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*/ |
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if (yrs > 169) |
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return -EINVAL; |
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if (yrs >= 100) |
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yrs -= 100; |
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if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) |
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|| RTC_ALWAYS_BCD) { |
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sec = bin2bcd(sec); |
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min = bin2bcd(min); |
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hrs = bin2bcd(hrs); |
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day = bin2bcd(day); |
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mon = bin2bcd(mon); |
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yrs = bin2bcd(yrs); |
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century = bin2bcd(century); |
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} |
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spin_lock_irqsave(&rtc_lock, flags); |
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save_control = CMOS_READ(RTC_CONTROL); |
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CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL); |
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save_freq_select = CMOS_READ(RTC_FREQ_SELECT); |
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CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT); |
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#ifdef CONFIG_MACH_DECSTATION |
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CMOS_WRITE(real_yrs, RTC_DEC_YEAR); |
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#endif |
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CMOS_WRITE(yrs, RTC_YEAR); |
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CMOS_WRITE(mon, RTC_MONTH); |
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CMOS_WRITE(day, RTC_DAY_OF_MONTH); |
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CMOS_WRITE(hrs, RTC_HOURS); |
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CMOS_WRITE(min, RTC_MINUTES); |
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CMOS_WRITE(sec, RTC_SECONDS); |
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#ifdef CONFIG_ACPI |
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if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID && |
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acpi_gbl_FADT.century) |
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CMOS_WRITE(century, acpi_gbl_FADT.century); |
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#endif |
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CMOS_WRITE(save_control, RTC_CONTROL); |
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CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT); |
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spin_unlock_irqrestore(&rtc_lock, flags); |
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return 0; |
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} |
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EXPORT_SYMBOL_GPL(mc146818_set_time);
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