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-rw-r--r--arch/mn10300/kernel/time.c129
1 files changed, 129 insertions, 0 deletions
diff --git a/arch/mn10300/kernel/time.c b/arch/mn10300/kernel/time.c
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+/* MN10300 Low level time management
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ * - Derived from arch/i386/kernel/time.c
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/interrupt.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/smp.h>
+#include <linux/profile.h>
+#include <asm/irq.h>
+#include <asm/div64.h>
+#include <asm/processor.h>
+#include <asm/intctl-regs.h>
+#include <asm/rtc.h>
+
+#ifdef CONFIG_MN10300_RTC
+unsigned long mn10300_ioclk; /* system I/O clock frequency */
+unsigned long mn10300_iobclk; /* system I/O clock frequency */
+unsigned long mn10300_tsc_per_HZ; /* number of ioclks per jiffy */
+#endif /* CONFIG_MN10300_RTC */
+
+static unsigned long mn10300_last_tsc; /* time-stamp counter at last time
+ * interrupt occurred */
+
+static irqreturn_t timer_interrupt(int irq, void *dev_id);
+
+static struct irqaction timer_irq = {
+ .handler = timer_interrupt,
+ .flags = IRQF_DISABLED | IRQF_SHARED | IRQF_TIMER,
+ .mask = CPU_MASK_NONE,
+ .name = "timer",
+};
+
+/*
+ * scheduler clock - returns current time in nanosec units.
+ */
+unsigned long long sched_clock(void)
+{
+ union {
+ unsigned long long l;
+ u32 w[2];
+ } quot;
+
+ quot.w[0] = mn10300_last_tsc - get_cycles();
+ quot.w[1] = 1000000000;
+
+ asm("mulu %2,%3,%0,%1"
+ : "=r"(quot.w[1]), "=r"(quot.w[0])
+ : "0"(quot.w[1]), "1"(quot.w[0])
+ : "cc");
+
+ do_div(quot.l, MN10300_TSCCLK);
+
+ return quot.l;
+}
+
+/*
+ * advance the kernel's time keeping clocks (xtime and jiffies)
+ * - we use Timer 0 & 1 cascaded as a clock to nudge us the next time
+ * there's a need to update
+ */
+static irqreturn_t timer_interrupt(int irq, void *dev_id)
+{
+ unsigned tsc, elapse;
+
+ write_seqlock(&xtime_lock);
+
+ while (tsc = get_cycles(),
+ elapse = mn10300_last_tsc - tsc, /* time elapsed since last
+ * tick */
+ elapse > MN10300_TSC_PER_HZ
+ ) {
+ mn10300_last_tsc -= MN10300_TSC_PER_HZ;
+
+ /* advance the kernel's time tracking system */
+ profile_tick(CPU_PROFILING);
+ do_timer(1);
+ update_process_times(user_mode(get_irq_regs()));
+ check_rtc_time();
+ }
+
+ write_sequnlock(&xtime_lock);
+ return IRQ_HANDLED;
+}
+
+/*
+ * initialise the various timers used by the main part of the kernel
+ */
+void __init time_init(void)
+{
+ /* we need the prescalar running to be able to use IOCLK/8
+ * - IOCLK runs at 1/4 (ST5 open) or 1/8 (ST5 closed) internal CPU clock
+ * - IOCLK runs at Fosc rate (crystal speed)
+ */
+ TMPSCNT |= TMPSCNT_ENABLE;
+
+ startup_timestamp_counter();
+
+ printk(KERN_INFO
+ "timestamp counter I/O clock running at %lu.%02lu"
+ " (calibrated against RTC)\n",
+ MN10300_TSCCLK / 1000000, (MN10300_TSCCLK / 10000) % 100);
+
+ xtime.tv_sec = get_initial_rtc_time();
+ xtime.tv_nsec = 0;
+
+ mn10300_last_tsc = TMTSCBC;
+
+ /* use timer 0 & 1 cascaded to tick at as close to HZ as possible */
+ setup_irq(TMJCIRQ, &timer_irq);
+
+ set_intr_level(TMJCIRQ, TMJCICR_LEVEL);
+
+ startup_jiffies_counter();
+
+#ifdef CONFIG_MN10300_WD_TIMER
+ /* start the watchdog timer */
+ watchdog_go();
+#endif
+}