/*
* arch/arm/mach-pxa/time.c
*
- * Author: Nicolas Pitre
- * Created: Jun 15, 2001
- * Copyright: MontaVista Software Inc.
+ * PXA clocksource, clockevents, and OST interrupt handlers.
+ * Copyright (c) 2007 by Bill Gatliff <bgat@billgatliff.com>.
+ *
+ * Derived from Nicolas Pitre's PXA timer handler Copyright (c) 2001
+ * by MontaVista Software, Inc. (Nico, your code rocks!)
*
* 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
#include <linux/kernel.h>
#include <linux/init.h>
-#include <linux/delay.h>
#include <linux/interrupt.h>
-#include <linux/time.h>
-#include <linux/signal.h>
-#include <linux/errno.h>
+#include <linux/clockchips.h>
#include <linux/sched.h>
-#include <linux/clocksource.h>
+#include <linux/cnt32_to_63.h>
-#include <asm/system.h>
-#include <asm/hardware.h>
-#include <asm/io.h>
-#include <asm/leds.h>
-#include <asm/irq.h>
+#include <asm/div64.h>
#include <asm/mach/irq.h>
#include <asm/mach/time.h>
-#include <asm/arch/pxa-regs.h>
+#include <mach/regs-ost.h>
+
+/*
+ * This is PXA's sched_clock implementation. This has a resolution
+ * of at least 308 ns and a maximum value of 208 days.
+ *
+ * The return value is guaranteed to be monotonic in that range as
+ * long as there is always less than 582 seconds between successive
+ * calls to sched_clock() which should always be the case in practice.
+ */
+
+#define OSCR2NS_SCALE_FACTOR 10
+static unsigned long oscr2ns_scale;
-static inline unsigned long pxa_get_rtc_time(void)
+static void __init set_oscr2ns_scale(unsigned long oscr_rate)
{
- return RCNR;
+ unsigned long long v = 1000000000ULL << OSCR2NS_SCALE_FACTOR;
+ do_div(v, oscr_rate);
+ oscr2ns_scale = v;
+ /*
+ * We want an even value to automatically clear the top bit
+ * returned by cnt32_to_63() without an additional run time
+ * instruction. So if the LSB is 1 then round it up.
+ */
+ if (oscr2ns_scale & 1)
+ oscr2ns_scale++;
}
-static int pxa_set_rtc(void)
+unsigned long long sched_clock(void)
{
- unsigned long current_time = xtime.tv_sec;
-
- if (RTSR & RTSR_ALE) {
- /* make sure not to forward the clock over an alarm */
- unsigned long alarm = RTAR;
- if (current_time >= alarm && alarm >= RCNR)
- return -ERESTARTSYS;
- }
- RCNR = current_time;
- return 0;
+ unsigned long long v = cnt32_to_63(OSCR);
+ return (v * oscr2ns_scale) >> OSCR2NS_SCALE_FACTOR;
}
-#ifdef CONFIG_NO_IDLE_HZ
-static unsigned long initial_match;
-static int match_posponed;
-#endif
+
+#define MIN_OSCR_DELTA 16
static irqreturn_t
-pxa_timer_interrupt(int irq, void *dev_id)
+pxa_ost0_interrupt(int irq, void *dev_id)
{
- int next_match;
+ struct clock_event_device *c = dev_id;
- write_seqlock(&xtime_lock);
+ /* Disarm the compare/match, signal the event. */
+ OIER &= ~OIER_E0;
+ OSSR = OSSR_M0;
+ c->event_handler(c);
-#ifdef CONFIG_NO_IDLE_HZ
- if (match_posponed) {
- match_posponed = 0;
- OSMR0 = initial_match;
- }
-#endif
+ return IRQ_HANDLED;
+}
- /* Loop until we get ahead of the free running timer.
- * This ensures an exact clock tick count and time accuracy.
- * Since IRQs are disabled at this point, coherence between
- * lost_ticks(updated in do_timer()) and the match reg value is
- * ensured, hence we can use do_gettimeofday() from interrupt
- * handlers.
- *
- * HACK ALERT: it seems that the PXA timer regs aren't updated right
- * away in all cases when a write occurs. We therefore compare with
- * 8 instead of 0 in the while() condition below to avoid missing a
- * match if OSCR has already reached the next OSMR value.
- * Experience has shown that up to 6 ticks are needed to work around
- * this problem, but let's use 8 to be conservative. Note that this
- * affect things only when the timer IRQ has been delayed by nearly
- * exactly one tick period which should be a pretty rare event.
- */
- do {
- timer_tick();
- OSSR = OSSR_M0; /* Clear match on timer 0 */
- next_match = (OSMR0 += LATCH);
- } while( (signed long)(next_match - OSCR) <= 8 );
+static int
+pxa_osmr0_set_next_event(unsigned long delta, struct clock_event_device *dev)
+{
+ unsigned long next, oscr;
- write_sequnlock(&xtime_lock);
+ OIER |= OIER_E0;
+ next = OSCR + delta;
+ OSMR0 = next;
+ oscr = OSCR;
- return IRQ_HANDLED;
+ return (signed)(next - oscr) <= MIN_OSCR_DELTA ? -ETIME : 0;
+}
+
+static void
+pxa_osmr0_set_mode(enum clock_event_mode mode, struct clock_event_device *dev)
+{
+ switch (mode) {
+ case CLOCK_EVT_MODE_ONESHOT:
+ OIER &= ~OIER_E0;
+ OSSR = OSSR_M0;
+ break;
+
+ case CLOCK_EVT_MODE_UNUSED:
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ /* initializing, released, or preparing for suspend */
+ OIER &= ~OIER_E0;
+ OSSR = OSSR_M0;
+ break;
+
+ case CLOCK_EVT_MODE_RESUME:
+ case CLOCK_EVT_MODE_PERIODIC:
+ break;
+ }
}
-static struct irqaction pxa_timer_irq = {
- .name = "PXA Timer Tick",
- .flags = IRQF_DISABLED | IRQF_TIMER,
- .handler = pxa_timer_interrupt,
+static struct clock_event_device ckevt_pxa_osmr0 = {
+ .name = "osmr0",
+ .features = CLOCK_EVT_FEAT_ONESHOT,
+ .shift = 32,
+ .rating = 200,
+ .set_next_event = pxa_osmr0_set_next_event,
+ .set_mode = pxa_osmr0_set_mode,
};
-static cycle_t pxa_get_cycles(void)
+static cycle_t pxa_read_oscr(struct clocksource *cs)
{
return OSCR;
}
-static struct clocksource clocksource_pxa = {
- .name = "pxa_timer",
+static struct clocksource cksrc_pxa_oscr0 = {
+ .name = "oscr0",
.rating = 200,
- .read = pxa_get_cycles,
+ .read = pxa_read_oscr,
.mask = CLOCKSOURCE_MASK(32),
.shift = 20,
- .is_continuous = 1,
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static struct irqaction pxa_ost0_irq = {
+ .name = "ost0",
+ .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
+ .handler = pxa_ost0_interrupt,
+ .dev_id = &ckevt_pxa_osmr0,
};
static void __init pxa_timer_init(void)
{
- struct timespec tv;
- unsigned long flags;
+ unsigned long clock_tick_rate = get_clock_tick_rate();
- set_rtc = pxa_set_rtc;
+ OIER = 0;
+ OSSR = OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3;
- tv.tv_nsec = 0;
- tv.tv_sec = pxa_get_rtc_time();
- do_settimeofday(&tv);
+ set_oscr2ns_scale(clock_tick_rate);
- OIER = 0; /* disable any timer interrupts */
- OSSR = 0xf; /* clear status on all timers */
- setup_irq(IRQ_OST0, &pxa_timer_irq);
- local_irq_save(flags);
- OIER = OIER_E0; /* enable match on timer 0 to cause interrupts */
- OSMR0 = OSCR + LATCH; /* set initial match */
- local_irq_restore(flags);
+ ckevt_pxa_osmr0.mult =
+ div_sc(clock_tick_rate, NSEC_PER_SEC, ckevt_pxa_osmr0.shift);
+ ckevt_pxa_osmr0.max_delta_ns =
+ clockevent_delta2ns(0x7fffffff, &ckevt_pxa_osmr0);
+ ckevt_pxa_osmr0.min_delta_ns =
+ clockevent_delta2ns(MIN_OSCR_DELTA * 2, &ckevt_pxa_osmr0) + 1;
+ ckevt_pxa_osmr0.cpumask = cpumask_of(0);
- /*
- * OSCR runs continuously on PXA and is not written to,
- * so we can use it as clock source directly.
- */
- clocksource_pxa.mult =
- clocksource_hz2mult(CLOCK_TICK_RATE, clocksource_pxa.shift);
- clocksource_register(&clocksource_pxa);
-}
+ cksrc_pxa_oscr0.mult =
+ clocksource_hz2mult(clock_tick_rate, cksrc_pxa_oscr0.shift);
-#ifdef CONFIG_NO_IDLE_HZ
-static int pxa_dyn_tick_enable_disable(void)
-{
- /* nothing to do */
- return 0;
-}
+ setup_irq(IRQ_OST0, &pxa_ost0_irq);
-static void pxa_dyn_tick_reprogram(unsigned long ticks)
-{
- if (ticks > 1) {
- initial_match = OSMR0;
- OSMR0 = initial_match + ticks * LATCH;
- match_posponed = 1;
- }
+ clocksource_register(&cksrc_pxa_oscr0);
+ clockevents_register_device(&ckevt_pxa_osmr0);
}
-static irqreturn_t
-pxa_dyn_tick_handler(int irq, void *dev_id)
-{
- if (match_posponed) {
- match_posponed = 0;
- OSMR0 = initial_match;
- if ( (signed long)(initial_match - OSCR) <= 8 )
- return pxa_timer_interrupt(irq, dev_id);
- }
- return IRQ_NONE;
-}
-
-static struct dyn_tick_timer pxa_dyn_tick = {
- .enable = pxa_dyn_tick_enable_disable,
- .disable = pxa_dyn_tick_enable_disable,
- .reprogram = pxa_dyn_tick_reprogram,
- .handler = pxa_dyn_tick_handler,
-};
-#endif
-
#ifdef CONFIG_PM
-static unsigned long osmr[4], oier;
+static unsigned long osmr[4], oier, oscr;
static void pxa_timer_suspend(void)
{
osmr[2] = OSMR2;
osmr[3] = OSMR3;
oier = OIER;
+ oscr = OSCR;
}
static void pxa_timer_resume(void)
{
+ /*
+ * Ensure that we have at least MIN_OSCR_DELTA between match
+ * register 0 and the OSCR, to guarantee that we will receive
+ * the one-shot timer interrupt. We adjust OSMR0 in preference
+ * to OSCR to guarantee that OSCR is monotonically incrementing.
+ */
+ if (osmr[0] - oscr < MIN_OSCR_DELTA)
+ osmr[0] += MIN_OSCR_DELTA;
+
OSMR0 = osmr[0];
OSMR1 = osmr[1];
OSMR2 = osmr[2];
OSMR3 = osmr[3];
OIER = oier;
-
- /*
- * OSMR0 is the system timer: make sure OSCR is sufficiently behind
- */
- OSCR = OSMR0 - LATCH;
+ OSCR = oscr;
}
#else
#define pxa_timer_suspend NULL
.init = pxa_timer_init,
.suspend = pxa_timer_suspend,
.resume = pxa_timer_resume,
-#ifdef CONFIG_NO_IDLE_HZ
- .dyn_tick = &pxa_dyn_tick,
-#endif
};
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff