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-rw-r--r--arch/avr32/kernel/time.c148
1 files changed, 148 insertions, 0 deletions
diff --git a/arch/avr32/kernel/time.c b/arch/avr32/kernel/time.c
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+++ b/arch/avr32/kernel/time.c
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+/*
+ * Copyright (C) 2004-2007 Atmel Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/time.h>
+
+#include <asm/sysreg.h>
+
+#include <mach/pm.h>
+
+
+static cycle_t read_cycle_count(struct clocksource *cs)
+{
+ return (cycle_t)sysreg_read(COUNT);
+}
+
+/*
+ * The architectural cycle count registers are a fine clocksource unless
+ * the system idle loop use sleep states like "idle": the CPU cycles
+ * measured by COUNT (and COMPARE) don't happen during sleep states.
+ * Their duration also changes if cpufreq changes the CPU clock rate.
+ * So we rate the clocksource using COUNT as very low quality.
+ */
+static struct clocksource counter = {
+ .name = "avr32_counter",
+ .rating = 50,
+ .read = read_cycle_count,
+ .mask = CLOCKSOURCE_MASK(32),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static irqreturn_t timer_interrupt(int irq, void *dev_id)
+{
+ struct clock_event_device *evdev = dev_id;
+
+ if (unlikely(!(intc_get_pending(0) & 1)))
+ return IRQ_NONE;
+
+ /*
+ * Disable the interrupt until the clockevent subsystem
+ * reprograms it.
+ */
+ sysreg_write(COMPARE, 0);
+
+ evdev->event_handler(evdev);
+ return IRQ_HANDLED;
+}
+
+static struct irqaction timer_irqaction = {
+ .handler = timer_interrupt,
+ /* Oprofile uses the same irq as the timer, so allow it to be shared */
+ .flags = IRQF_TIMER | IRQF_DISABLED | IRQF_SHARED,
+ .name = "avr32_comparator",
+};
+
+static int comparator_next_event(unsigned long delta,
+ struct clock_event_device *evdev)
+{
+ unsigned long flags;
+
+ raw_local_irq_save(flags);
+
+ /* The time to read COUNT then update COMPARE must be less
+ * than the min_delta_ns value for this clockevent source.
+ */
+ sysreg_write(COMPARE, (sysreg_read(COUNT) + delta) ? : 1);
+
+ raw_local_irq_restore(flags);
+
+ return 0;
+}
+
+static void comparator_mode(enum clock_event_mode mode,
+ struct clock_event_device *evdev)
+{
+ switch (mode) {
+ case CLOCK_EVT_MODE_ONESHOT:
+ pr_debug("%s: start\n", evdev->name);
+ /* FALLTHROUGH */
+ case CLOCK_EVT_MODE_RESUME:
+ cpu_disable_idle_sleep();
+ break;
+ case CLOCK_EVT_MODE_UNUSED:
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ sysreg_write(COMPARE, 0);
+ pr_debug("%s: stop\n", evdev->name);
+ cpu_enable_idle_sleep();
+ break;
+ default:
+ BUG();
+ }
+}
+
+static struct clock_event_device comparator = {
+ .name = "avr32_comparator",
+ .features = CLOCK_EVT_FEAT_ONESHOT,
+ .shift = 16,
+ .rating = 50,
+ .set_next_event = comparator_next_event,
+ .set_mode = comparator_mode,
+};
+
+void read_persistent_clock(struct timespec *ts)
+{
+ ts->tv_sec = mktime(2007, 1, 1, 0, 0, 0);
+ ts->tv_nsec = 0;
+}
+
+void __init time_init(void)
+{
+ unsigned long counter_hz;
+ int ret;
+
+ /* figure rate for counter */
+ counter_hz = clk_get_rate(boot_cpu_data.clk);
+ ret = clocksource_register_hz(&counter, counter_hz);
+ if (ret)
+ pr_debug("timer: could not register clocksource: %d\n", ret);
+
+ /* setup COMPARE clockevent */
+ comparator.mult = div_sc(counter_hz, NSEC_PER_SEC, comparator.shift);
+ comparator.max_delta_ns = clockevent_delta2ns((u32)~0, &comparator);
+ comparator.min_delta_ns = clockevent_delta2ns(50, &comparator) + 1;
+ comparator.cpumask = cpumask_of(0);
+
+ sysreg_write(COMPARE, 0);
+ timer_irqaction.dev_id = &comparator;
+
+ ret = setup_irq(0, &timer_irqaction);
+ if (ret)
+ pr_debug("timer: could not request IRQ 0: %d\n", ret);
+ else {
+ clockevents_register_device(&comparator);
+
+ pr_info("%s: irq 0, %lu.%03lu MHz\n", comparator.name,
+ ((counter_hz + 500) / 1000) / 1000,
+ ((counter_hz + 500) / 1000) % 1000);
+ }
+}