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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/cris/arch-v10/kernel/time.c
downloadconfigs-2.6.12-rc2.tar.gz
Linux-2.6.12-rc2v2.6.12-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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+/* $Id: time.c,v 1.5 2004/09/29 06:12:46 starvik Exp $
+ *
+ * linux/arch/cris/arch-v10/kernel/time.c
+ *
+ * Copyright (C) 1991, 1992, 1995 Linus Torvalds
+ * Copyright (C) 1999-2002 Axis Communications AB
+ *
+ */
+
+#include <linux/config.h>
+#include <linux/timex.h>
+#include <linux/time.h>
+#include <linux/jiffies.h>
+#include <linux/interrupt.h>
+#include <linux/swap.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <asm/arch/svinto.h>
+#include <asm/types.h>
+#include <asm/signal.h>
+#include <asm/io.h>
+#include <asm/delay.h>
+#include <asm/rtc.h>
+
+/* define this if you need to use print_timestamp */
+/* it will make jiffies at 96 hz instead of 100 hz though */
+#undef USE_CASCADE_TIMERS
+
+extern void update_xtime_from_cmos(void);
+extern int set_rtc_mmss(unsigned long nowtime);
+extern int setup_irq(int, struct irqaction *);
+extern int have_rtc;
+
+unsigned long get_ns_in_jiffie(void)
+{
+ unsigned char timer_count, t1;
+ unsigned short presc_count;
+ unsigned long ns;
+ unsigned long flags;
+
+ local_irq_save(flags);
+ local_irq_disable();
+ timer_count = *R_TIMER0_DATA;
+ presc_count = *R_TIM_PRESC_STATUS;
+ /* presc_count might be wrapped */
+ t1 = *R_TIMER0_DATA;
+
+ if (timer_count != t1){
+ /* it wrapped, read prescaler again... */
+ presc_count = *R_TIM_PRESC_STATUS;
+ timer_count = t1;
+ }
+ local_irq_restore(flags);
+ if (presc_count >= PRESCALE_VALUE/2 ){
+ presc_count = PRESCALE_VALUE - presc_count + PRESCALE_VALUE/2;
+ } else {
+ presc_count = PRESCALE_VALUE - presc_count - PRESCALE_VALUE/2;
+ }
+
+ ns = ( (TIMER0_DIV - timer_count) * ((1000000000/HZ)/TIMER0_DIV )) +
+ ( (presc_count) * (1000000000/PRESCALE_FREQ));
+ return ns;
+}
+
+unsigned long do_slow_gettimeoffset(void)
+{
+ unsigned long count, t1;
+ unsigned long usec_count = 0;
+ unsigned short presc_count;
+
+ static unsigned long count_p = TIMER0_DIV;/* for the first call after boot */
+ static unsigned long jiffies_p = 0;
+
+ /*
+ * cache volatile jiffies temporarily; we have IRQs turned off.
+ */
+ unsigned long jiffies_t;
+
+ /* The timer interrupt comes from Etrax timer 0. In order to get
+ * better precision, we check the current value. It might have
+ * underflowed already though.
+ */
+
+#ifndef CONFIG_SVINTO_SIM
+ /* Not available in the xsim simulator. */
+ count = *R_TIMER0_DATA;
+ presc_count = *R_TIM_PRESC_STATUS;
+ /* presc_count might be wrapped */
+ t1 = *R_TIMER0_DATA;
+ if (count != t1){
+ /* it wrapped, read prescaler again... */
+ presc_count = *R_TIM_PRESC_STATUS;
+ count = t1;
+ }
+#else
+ count = 0;
+ presc_count = 0;
+#endif
+
+ jiffies_t = jiffies;
+
+ /*
+ * avoiding timer inconsistencies (they are rare, but they happen)...
+ * there are one problem that must be avoided here:
+ * 1. the timer counter underflows
+ */
+ if( jiffies_t == jiffies_p ) {
+ if( count > count_p ) {
+ /* Timer wrapped, use new count and prescale
+ * increase the time corresponding to one jiffie
+ */
+ usec_count = 1000000/HZ;
+ }
+ } else
+ jiffies_p = jiffies_t;
+ count_p = count;
+ if (presc_count >= PRESCALE_VALUE/2 ){
+ presc_count = PRESCALE_VALUE - presc_count + PRESCALE_VALUE/2;
+ } else {
+ presc_count = PRESCALE_VALUE - presc_count - PRESCALE_VALUE/2;
+ }
+ /* Convert timer value to usec */
+ usec_count += ( (TIMER0_DIV - count) * (1000000/HZ)/TIMER0_DIV ) +
+ (( (presc_count) * (1000000000/PRESCALE_FREQ))/1000);
+
+ return usec_count;
+}
+
+/* Excerpt from the Etrax100 HSDD about the built-in watchdog:
+ *
+ * 3.10.4 Watchdog timer
+
+ * When the watchdog timer is started, it generates an NMI if the watchdog
+ * isn't restarted or stopped within 0.1 s. If it still isn't restarted or
+ * stopped after an additional 3.3 ms, the watchdog resets the chip.
+ * The watchdog timer is stopped after reset. The watchdog timer is controlled
+ * by the R_WATCHDOG register. The R_WATCHDOG register contains an enable bit
+ * and a 3-bit key value. The effect of writing to the R_WATCHDOG register is
+ * described in the table below:
+ *
+ * Watchdog Value written:
+ * state: To enable: To key: Operation:
+ * -------- ---------- ------- ----------
+ * stopped 0 X No effect.
+ * stopped 1 key_val Start watchdog with key = key_val.
+ * started 0 ~key Stop watchdog
+ * started 1 ~key Restart watchdog with key = ~key.
+ * started X new_key_val Change key to new_key_val.
+ *
+ * Note: '~' is the bitwise NOT operator.
+ *
+ */
+
+/* right now, starting the watchdog is the same as resetting it */
+#define start_watchdog reset_watchdog
+
+#if defined(CONFIG_ETRAX_WATCHDOG) && !defined(CONFIG_SVINTO_SIM)
+static int watchdog_key = 0; /* arbitrary number */
+#endif
+
+/* number of pages to consider "out of memory". it is normal that the memory
+ * is used though, so put this really low.
+ */
+
+#define WATCHDOG_MIN_FREE_PAGES 8
+
+void
+reset_watchdog(void)
+{
+#if defined(CONFIG_ETRAX_WATCHDOG) && !defined(CONFIG_SVINTO_SIM)
+ /* only keep watchdog happy as long as we have memory left! */
+ if(nr_free_pages() > WATCHDOG_MIN_FREE_PAGES) {
+ /* reset the watchdog with the inverse of the old key */
+ watchdog_key ^= 0x7; /* invert key, which is 3 bits */
+ *R_WATCHDOG = IO_FIELD(R_WATCHDOG, key, watchdog_key) |
+ IO_STATE(R_WATCHDOG, enable, start);
+ }
+#endif
+}
+
+/* stop the watchdog - we still need the correct key */
+
+void
+stop_watchdog(void)
+{
+#if defined(CONFIG_ETRAX_WATCHDOG) && !defined(CONFIG_SVINTO_SIM)
+ watchdog_key ^= 0x7; /* invert key, which is 3 bits */
+ *R_WATCHDOG = IO_FIELD(R_WATCHDOG, key, watchdog_key) |
+ IO_STATE(R_WATCHDOG, enable, stop);
+#endif
+}
+
+/* last time the cmos clock got updated */
+static long last_rtc_update = 0;
+
+/*
+ * timer_interrupt() needs to keep up the real-time clock,
+ * as well as call the "do_timer()" routine every clocktick
+ */
+
+//static unsigned short myjiff; /* used by our debug routine print_timestamp */
+
+extern void cris_do_profile(struct pt_regs *regs);
+
+static inline irqreturn_t
+timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+ /* acknowledge the timer irq */
+
+#ifdef USE_CASCADE_TIMERS
+ *R_TIMER_CTRL =
+ IO_FIELD( R_TIMER_CTRL, timerdiv1, 0) |
+ IO_FIELD( R_TIMER_CTRL, timerdiv0, 0) |
+ IO_STATE( R_TIMER_CTRL, i1, clr) |
+ IO_STATE( R_TIMER_CTRL, tm1, run) |
+ IO_STATE( R_TIMER_CTRL, clksel1, cascade0) |
+ IO_STATE( R_TIMER_CTRL, i0, clr) |
+ IO_STATE( R_TIMER_CTRL, tm0, run) |
+ IO_STATE( R_TIMER_CTRL, clksel0, c6250kHz);
+#else
+ *R_TIMER_CTRL = r_timer_ctrl_shadow |
+ IO_STATE(R_TIMER_CTRL, i0, clr);
+#endif
+
+ /* reset watchdog otherwise it resets us! */
+
+ reset_watchdog();
+
+ /* call the real timer interrupt handler */
+
+ do_timer(regs);
+
+ cris_do_profile(regs); /* Save profiling information */
+
+ /*
+ * If we have an externally synchronized Linux clock, then update
+ * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
+ * called as close as possible to 500 ms before the new second starts.
+ *
+ * The division here is not time critical since it will run once in
+ * 11 minutes
+ */
+ if ((time_status & STA_UNSYNC) == 0 &&
+ xtime.tv_sec > last_rtc_update + 660 &&
+ (xtime.tv_nsec / 1000) >= 500000 - (tick_nsec / 1000) / 2 &&
+ (xtime.tv_nsec / 1000) <= 500000 + (tick_nsec / 1000) / 2) {
+ if (set_rtc_mmss(xtime.tv_sec) == 0)
+ last_rtc_update = xtime.tv_sec;
+ else
+ last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
+ }
+ return IRQ_HANDLED;
+}
+
+/* timer is SA_SHIRQ so drivers can add stuff to the timer irq chain
+ * it needs to be SA_INTERRUPT to make the jiffies update work properly
+ */
+
+static struct irqaction irq2 = { timer_interrupt, SA_SHIRQ | SA_INTERRUPT,
+ CPU_MASK_NONE, "timer", NULL, NULL};
+
+void __init
+time_init(void)
+{
+ /* probe for the RTC and read it if it exists
+ * Before the RTC can be probed the loops_per_usec variable needs
+ * to be initialized to make usleep work. A better value for
+ * loops_per_usec is calculated by the kernel later once the
+ * clock has started.
+ */
+ loops_per_usec = 50;
+
+ if(RTC_INIT() < 0) {
+ /* no RTC, start at 1980 */
+ xtime.tv_sec = 0;
+ xtime.tv_nsec = 0;
+ have_rtc = 0;
+ } else {
+ /* get the current time */
+ have_rtc = 1;
+ update_xtime_from_cmos();
+ }
+
+ /*
+ * Initialize wall_to_monotonic such that adding it to xtime will yield zero, the
+ * tv_nsec field must be normalized (i.e., 0 <= nsec < NSEC_PER_SEC).
+ */
+ set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec);
+
+ /* Setup the etrax timers
+ * Base frequency is 25000 hz, divider 250 -> 100 HZ
+ * In normal mode, we use timer0, so timer1 is free. In cascade
+ * mode (which we sometimes use for debugging) both timers are used.
+ * Remember that linux/timex.h contains #defines that rely on the
+ * timer settings below (hz and divide factor) !!!
+ */
+
+#ifdef USE_CASCADE_TIMERS
+ *R_TIMER_CTRL =
+ IO_FIELD( R_TIMER_CTRL, timerdiv1, 0) |
+ IO_FIELD( R_TIMER_CTRL, timerdiv0, 0) |
+ IO_STATE( R_TIMER_CTRL, i1, nop) |
+ IO_STATE( R_TIMER_CTRL, tm1, stop_ld) |
+ IO_STATE( R_TIMER_CTRL, clksel1, cascade0) |
+ IO_STATE( R_TIMER_CTRL, i0, nop) |
+ IO_STATE( R_TIMER_CTRL, tm0, stop_ld) |
+ IO_STATE( R_TIMER_CTRL, clksel0, c6250kHz);
+
+ *R_TIMER_CTRL = r_timer_ctrl_shadow =
+ IO_FIELD( R_TIMER_CTRL, timerdiv1, 0) |
+ IO_FIELD( R_TIMER_CTRL, timerdiv0, 0) |
+ IO_STATE( R_TIMER_CTRL, i1, nop) |
+ IO_STATE( R_TIMER_CTRL, tm1, run) |
+ IO_STATE( R_TIMER_CTRL, clksel1, cascade0) |
+ IO_STATE( R_TIMER_CTRL, i0, nop) |
+ IO_STATE( R_TIMER_CTRL, tm0, run) |
+ IO_STATE( R_TIMER_CTRL, clksel0, c6250kHz);
+#else
+ *R_TIMER_CTRL =
+ IO_FIELD(R_TIMER_CTRL, timerdiv1, 192) |
+ IO_FIELD(R_TIMER_CTRL, timerdiv0, TIMER0_DIV) |
+ IO_STATE(R_TIMER_CTRL, i1, nop) |
+ IO_STATE(R_TIMER_CTRL, tm1, stop_ld) |
+ IO_STATE(R_TIMER_CTRL, clksel1, c19k2Hz) |
+ IO_STATE(R_TIMER_CTRL, i0, nop) |
+ IO_STATE(R_TIMER_CTRL, tm0, stop_ld) |
+ IO_STATE(R_TIMER_CTRL, clksel0, flexible);
+
+ *R_TIMER_CTRL = r_timer_ctrl_shadow =
+ IO_FIELD(R_TIMER_CTRL, timerdiv1, 192) |
+ IO_FIELD(R_TIMER_CTRL, timerdiv0, TIMER0_DIV) |
+ IO_STATE(R_TIMER_CTRL, i1, nop) |
+ IO_STATE(R_TIMER_CTRL, tm1, run) |
+ IO_STATE(R_TIMER_CTRL, clksel1, c19k2Hz) |
+ IO_STATE(R_TIMER_CTRL, i0, nop) |
+ IO_STATE(R_TIMER_CTRL, tm0, run) |
+ IO_STATE(R_TIMER_CTRL, clksel0, flexible);
+
+ *R_TIMER_PRESCALE = PRESCALE_VALUE;
+#endif
+
+ *R_IRQ_MASK0_SET =
+ IO_STATE(R_IRQ_MASK0_SET, timer0, set); /* unmask the timer irq */
+
+ /* now actually register the timer irq handler that calls timer_interrupt() */
+
+ setup_irq(2, &irq2); /* irq 2 is the timer0 irq in etrax */
+
+ /* enable watchdog if we should use one */
+
+#if defined(CONFIG_ETRAX_WATCHDOG) && !defined(CONFIG_SVINTO_SIM)
+ printk("Enabling watchdog...\n");
+ start_watchdog();
+
+ /* If we use the hardware watchdog, we want to trap it as an NMI
+ and dump registers before it resets us. For this to happen, we
+ must set the "m" NMI enable flag (which once set, is unset only
+ when an NMI is taken).
+
+ The same goes for the external NMI, but that doesn't have any
+ driver or infrastructure support yet. */
+ asm ("setf m");
+
+ *R_IRQ_MASK0_SET =
+ IO_STATE(R_IRQ_MASK0_SET, watchdog_nmi, set);
+ *R_VECT_MASK_SET =
+ IO_STATE(R_VECT_MASK_SET, nmi, set);
+#endif
+}