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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 22:20:36 (GMT)
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 22:20:36 (GMT)
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/mips/dec/time.c
downloadlinux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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+/*
+ * linux/arch/mips/dec/time.c
+ *
+ * Copyright (C) 1991, 1992, 1995 Linus Torvalds
+ * Copyright (C) 2000, 2003 Maciej W. Rozycki
+ *
+ * This file contains the time handling details for PC-style clocks as
+ * found in some MIPS systems.
+ *
+ */
+#include <linux/bcd.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/mc146818rtc.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/param.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+#include <linux/time.h>
+#include <linux/types.h>
+
+#include <asm/bootinfo.h>
+#include <asm/cpu.h>
+#include <asm/div64.h>
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <asm/mipsregs.h>
+#include <asm/sections.h>
+#include <asm/time.h>
+
+#include <asm/dec/interrupts.h>
+#include <asm/dec/ioasic.h>
+#include <asm/dec/ioasic_addrs.h>
+#include <asm/dec/machtype.h>
+
+
+static unsigned long dec_rtc_get_time(void)
+{
+ unsigned int year, mon, day, hour, min, sec, real_year;
+ int i;
+
+ /* The Linux interpretation of the DS1287 clock register contents:
+ * When the Update-In-Progress (UIP) flag goes from 1 to 0, the
+ * RTC registers show the second which has precisely just started.
+ * Let's hope other operating systems interpret the RTC the same way.
+ */
+ /* read RTC exactly on falling edge of update flag */
+ for (i = 0; i < 1000000; i++) /* may take up to 1 second... */
+ if (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP)
+ break;
+ for (i = 0; i < 1000000; i++) /* must try at least 2.228 ms */
+ if (!(CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP))
+ break;
+ /* Isn't this overkill? UIP above should guarantee consistency */
+ do {
+ 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);
+ } while (sec != CMOS_READ(RTC_SECONDS));
+ if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
+ sec = BCD2BIN(sec);
+ min = BCD2BIN(min);
+ hour = BCD2BIN(hour);
+ day = BCD2BIN(day);
+ mon = BCD2BIN(mon);
+ year = BCD2BIN(year);
+ }
+ /*
+ * The PROM will reset the year to either '72 or '73.
+ * Therefore we store the real year separately, in one
+ * of unused BBU RAM locations.
+ */
+ real_year = CMOS_READ(RTC_DEC_YEAR);
+ year += real_year - 72 + 2000;
+
+ return mktime(year, mon, day, hour, min, sec);
+}
+
+/*
+ * In order to set the CMOS clock precisely, dec_rtc_set_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 Dallas
+ * DS1287 data sheet for details.
+ */
+static int dec_rtc_set_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)
+ cmos_minutes = BCD2BIN(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;
+ if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
+ real_minutes += 30; /* correct for half hour time zone */
+ real_minutes %= 60;
+
+ if (abs(real_minutes - cmos_minutes) < 30) {
+ if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
+ real_seconds = BIN2BCD(real_seconds);
+ real_minutes = BIN2BCD(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 DS1287 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;
+}
+
+
+static int dec_timer_state(void)
+{
+ return (CMOS_READ(RTC_REG_C) & RTC_PF) != 0;
+}
+
+static void dec_timer_ack(void)
+{
+ CMOS_READ(RTC_REG_C); /* Ack the RTC interrupt. */
+}
+
+static unsigned int dec_ioasic_hpt_read(void)
+{
+ /*
+ * The free-running counter is 32-bit which is good for about
+ * 2 minutes, 50 seconds at possible count rates of up to 25MHz.
+ */
+ return ioasic_read(IO_REG_FCTR);
+}
+
+static void dec_ioasic_hpt_init(unsigned int count)
+{
+ ioasic_write(IO_REG_FCTR, ioasic_read(IO_REG_FCTR) - count);
+}
+
+
+void __init dec_time_init(void)
+{
+ rtc_get_time = dec_rtc_get_time;
+ rtc_set_mmss = dec_rtc_set_mmss;
+
+ mips_timer_state = dec_timer_state;
+ mips_timer_ack = dec_timer_ack;
+
+ if (!cpu_has_counter && IOASIC) {
+ /* For pre-R4k systems we use the I/O ASIC's counter. */
+ mips_hpt_read = dec_ioasic_hpt_read;
+ mips_hpt_init = dec_ioasic_hpt_init;
+ }
+
+ /* Set up the rate of periodic DS1287 interrupts. */
+ CMOS_WRITE(RTC_REF_CLCK_32KHZ | (16 - LOG_2_HZ), RTC_REG_A);
+}
+
+EXPORT_SYMBOL(do_settimeofday);
+
+void __init dec_timer_setup(struct irqaction *irq)
+{
+ setup_irq(dec_interrupt[DEC_IRQ_RTC], irq);
+
+ /* Enable periodic DS1287 interrupts. */
+ CMOS_WRITE(CMOS_READ(RTC_REG_B) | RTC_PIE, RTC_REG_B);
+}