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authorRichard Henderson <rth@twiddle.net>2013-07-15 01:50:21 +0400
committerMatt Turner <mattst88@gmail.com>2013-11-17 04:33:21 +0400
commit4914d7b458e35a7db2f9c7dc6eb014620254bbbf (patch)
tree07bc9c2eedb174f0710dddca3950dcb12789236c /arch/alpha/kernel/time.c
parenta1659d6d128a7e0c2985bce7c957b66af1f71181 (diff)
downloadlinux-4914d7b458e35a7db2f9c7dc6eb014620254bbbf.tar.xz
alpha: Use qemu+cserve provided high-res clock and alarm.
QEMU provides a high-resolution timer and alarm; use this for a clock source and clock event source when available. Signed-off-by: Richard Henderson <rth@twiddle.net>
Diffstat (limited to 'arch/alpha/kernel/time.c')
-rw-r--r--arch/alpha/kernel/time.c98
1 files changed, 93 insertions, 5 deletions
diff --git a/arch/alpha/kernel/time.c b/arch/alpha/kernel/time.c
index 08ff3f502a76..ee39cee8064c 100644
--- a/arch/alpha/kernel/time.c
+++ b/arch/alpha/kernel/time.c
@@ -87,7 +87,7 @@ static inline __u32 rpcc(void)
static DEFINE_PER_CPU(struct clock_event_device, cpu_ce);
irqreturn_t
-timer_interrupt(int irq, void *dev)
+rtc_timer_interrupt(int irq, void *dev)
{
int cpu = smp_processor_id();
struct clock_event_device *ce = &per_cpu(cpu_ce, cpu);
@@ -118,8 +118,8 @@ rtc_ce_set_next_event(unsigned long evt, struct clock_event_device *ce)
return -EINVAL;
}
-void __init
-init_clockevent(void)
+static void __init
+init_rtc_clockevent(void)
{
int cpu = smp_processor_id();
struct clock_event_device *ce = &per_cpu(cpu_ce, cpu);
@@ -136,6 +136,75 @@ init_clockevent(void)
clockevents_config_and_register(ce, CONFIG_HZ, 0, 0);
}
+
+/*
+ * The QEMU clock as a clocksource primitive.
+ */
+
+static cycle_t
+qemu_cs_read(struct clocksource *cs)
+{
+ return qemu_get_vmtime();
+}
+
+static struct clocksource qemu_cs = {
+ .name = "qemu",
+ .rating = 400,
+ .read = qemu_cs_read,
+ .mask = CLOCKSOURCE_MASK(64),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+ .max_idle_ns = LONG_MAX
+};
+
+
+/*
+ * The QEMU alarm as a clock_event_device primitive.
+ */
+
+static void
+qemu_ce_set_mode(enum clock_event_mode mode, struct clock_event_device *ce)
+{
+ /* The mode member of CE is updated for us in generic code.
+ Just make sure that the event is disabled. */
+ qemu_set_alarm_abs(0);
+}
+
+static int
+qemu_ce_set_next_event(unsigned long evt, struct clock_event_device *ce)
+{
+ qemu_set_alarm_rel(evt);
+ return 0;
+}
+
+static irqreturn_t
+qemu_timer_interrupt(int irq, void *dev)
+{
+ int cpu = smp_processor_id();
+ struct clock_event_device *ce = &per_cpu(cpu_ce, cpu);
+
+ ce->event_handler(ce);
+ return IRQ_HANDLED;
+}
+
+static void __init
+init_qemu_clockevent(void)
+{
+ int cpu = smp_processor_id();
+ struct clock_event_device *ce = &per_cpu(cpu_ce, cpu);
+
+ *ce = (struct clock_event_device){
+ .name = "qemu",
+ .features = CLOCK_EVT_FEAT_ONESHOT,
+ .rating = 400,
+ .cpumask = cpumask_of(cpu),
+ .set_mode = qemu_ce_set_mode,
+ .set_next_event = qemu_ce_set_next_event,
+ };
+
+ clockevents_config_and_register(ce, NSEC_PER_SEC, 1000, LONG_MAX);
+}
+
+
void __init
common_init_rtc(void)
{
@@ -329,6 +398,15 @@ time_init(void)
unsigned long cycle_freq, tolerance;
long diff;
+ if (alpha_using_qemu) {
+ clocksource_register_hz(&qemu_cs, NSEC_PER_SEC);
+ init_qemu_clockevent();
+
+ timer_irqaction.handler = qemu_timer_interrupt;
+ init_rtc_irq();
+ return;
+ }
+
/* Calibrate CPU clock -- attempt #1. */
if (!est_cycle_freq)
est_cycle_freq = validate_cc_value(calibrate_cc_with_pit());
@@ -371,7 +449,17 @@ time_init(void)
/* Startup the timer source. */
alpha_mv.init_rtc();
+ init_rtc_clockevent();
+}
- /* Start up the clock event device. */
- init_clockevent();
+/* Initialize the clock_event_device for secondary cpus. */
+#ifdef CONFIG_SMP
+void __init
+init_clockevent(void)
+{
+ if (alpha_using_qemu)
+ init_qemu_clockevent();
+ else
+ init_rtc_clockevent();
}
+#endif