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-rw-r--r--arch/x86/kernel/rtc.c204
1 files changed, 204 insertions, 0 deletions
diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c
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+++ b/arch/x86/kernel/rtc.c
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+/*
+ * RTC related functions
+ */
+#include <linux/acpi.h>
+#include <linux/bcd.h>
+#include <linux/mc146818rtc.h>
+
+#include <asm/time.h>
+#include <asm/vsyscall.h>
+
+#ifdef CONFIG_X86_32
+# define CMOS_YEARS_OFFS 1900
+/*
+ * This is a special lock that is owned by the CPU and holds the index
+ * register we are working with. It is required for NMI access to the
+ * CMOS/RTC registers. See include/asm-i386/mc146818rtc.h for details.
+ */
+volatile unsigned long cmos_lock = 0;
+EXPORT_SYMBOL(cmos_lock);
+#else
+/*
+ * x86-64 systems only exists since 2002.
+ * This will work up to Dec 31, 2100
+ */
+# define CMOS_YEARS_OFFS 2000
+#endif
+
+DEFINE_SPINLOCK(rtc_lock);
+EXPORT_SYMBOL(rtc_lock);
+
+/*
+ * In order to set the CMOS clock precisely, set_rtc_mmss has to be
+ * called 500 ms after the second nowtime has started, because when
+ * nowtime is written into the registers of the CMOS clock, it will
+ * jump to the next second precisely 500 ms later. Check the Motorola
+ * MC146818A or Dallas DS12887 data sheet for details.
+ *
+ * BUG: This routine does not handle hour overflow properly; it just
+ * sets the minutes. Usually you'll only notice that after reboot!
+ */
+int mach_set_rtc_mmss(unsigned long nowtime)
+{
+ int retval = 0;
+ int real_seconds, real_minutes, cmos_minutes;
+ unsigned char save_control, save_freq_select;
+
+ /* tell the clock it's being set */
+ save_control = CMOS_READ(RTC_CONTROL);
+ CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
+
+ /* stop and reset prescaler */
+ save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
+ CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
+
+ cmos_minutes = CMOS_READ(RTC_MINUTES);
+ if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
+ BCD_TO_BIN(cmos_minutes);
+
+ /*
+ * since we're only adjusting minutes and seconds,
+ * don't interfere with hour overflow. This avoids
+ * messing with unknown time zones but requires your
+ * RTC not to be off by more than 15 minutes
+ */
+ real_seconds = nowtime % 60;
+ real_minutes = nowtime / 60;
+ /* correct for half hour time zone */
+ if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
+ real_minutes += 30;
+ real_minutes %= 60;
+
+ if (abs(real_minutes - cmos_minutes) < 30) {
+ if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
+ BIN_TO_BCD(real_seconds);
+ BIN_TO_BCD(real_minutes);
+ }
+ CMOS_WRITE(real_seconds,RTC_SECONDS);
+ CMOS_WRITE(real_minutes,RTC_MINUTES);
+ } else {
+ printk(KERN_WARNING
+ "set_rtc_mmss: can't update from %d to %d\n",
+ cmos_minutes, real_minutes);
+ retval = -1;
+ }
+
+ /* The following flags have to be released exactly in this order,
+ * otherwise the DS12887 (popular MC146818A clone with integrated
+ * battery and quartz) will not reset the oscillator and will not
+ * update precisely 500 ms later. You won't find this mentioned in
+ * the Dallas Semiconductor data sheets, but who believes data
+ * sheets anyway ... -- Markus Kuhn
+ */
+ CMOS_WRITE(save_control, RTC_CONTROL);
+ CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
+
+ return retval;
+}
+
+unsigned long mach_get_cmos_time(void)
+{
+ unsigned int year, mon, day, hour, min, sec, century = 0;
+
+ /*
+ * If UIP is clear, then we have >= 244 microseconds before
+ * RTC registers will be updated. Spec sheet says that this
+ * is the reliable way to read RTC - registers. If UIP is set
+ * then the register access might be invalid.
+ */
+ while ((CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
+ cpu_relax();
+
+ sec = CMOS_READ(RTC_SECONDS);
+ min = CMOS_READ(RTC_MINUTES);
+ hour = CMOS_READ(RTC_HOURS);
+ day = CMOS_READ(RTC_DAY_OF_MONTH);
+ mon = CMOS_READ(RTC_MONTH);
+ year = CMOS_READ(RTC_YEAR);
+
+#if defined(CONFIG_ACPI) && defined(CONFIG_X86_64)
+ /* CHECKME: Is this really 64bit only ??? */
+ if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
+ acpi_gbl_FADT.century)
+ century = CMOS_READ(acpi_gbl_FADT.century);
+#endif
+
+ if (RTC_ALWAYS_BCD || !(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)) {
+ BCD_TO_BIN(sec);
+ BCD_TO_BIN(min);
+ BCD_TO_BIN(hour);
+ BCD_TO_BIN(day);
+ BCD_TO_BIN(mon);
+ BCD_TO_BIN(year);
+ }
+
+ if (century) {
+ BCD_TO_BIN(century);
+ year += century * 100;
+ printk(KERN_INFO "Extended CMOS year: %d\n", century * 100);
+ } else {
+ year += CMOS_YEARS_OFFS;
+ if (year < 1970)
+ year += 100;
+ }
+
+ return mktime(year, mon, day, hour, min, sec);
+}
+
+/* Routines for accessing the CMOS RAM/RTC. */
+unsigned char rtc_cmos_read(unsigned char addr)
+{
+ unsigned char val;
+
+ lock_cmos_prefix(addr);
+ outb_p(addr, RTC_PORT(0));
+ val = inb_p(RTC_PORT(1));
+ lock_cmos_suffix(addr);
+ return val;
+}
+EXPORT_SYMBOL(rtc_cmos_read);
+
+void rtc_cmos_write(unsigned char val, unsigned char addr)
+{
+ lock_cmos_prefix(addr);
+ outb_p(addr, RTC_PORT(0));
+ outb_p(val, RTC_PORT(1));
+ lock_cmos_suffix(addr);
+}
+EXPORT_SYMBOL(rtc_cmos_write);
+
+static int set_rtc_mmss(unsigned long nowtime)
+{
+ int retval;
+ unsigned long flags;
+
+ spin_lock_irqsave(&rtc_lock, flags);
+ retval = set_wallclock(nowtime);
+ spin_unlock_irqrestore(&rtc_lock, flags);
+
+ return retval;
+}
+
+/* not static: needed by APM */
+unsigned long read_persistent_clock(void)
+{
+ unsigned long retval, flags;
+
+ spin_lock_irqsave(&rtc_lock, flags);
+ retval = get_wallclock();
+ spin_unlock_irqrestore(&rtc_lock, flags);
+
+ return retval;
+}
+
+int update_persistent_clock(struct timespec now)
+{
+ return set_rtc_mmss(now.tv_sec);
+}
+
+unsigned long long native_read_tsc(void)
+{
+ return __native_read_tsc();
+}
+EXPORT_SYMBOL(native_read_tsc);
+