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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/arm/mach-pxa/time.c
downloadlinux-stericsson-9e734775f7c22d2f89943ad6c745571f1930105f.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!
Diffstat (limited to 'arch/arm/mach-pxa/time.c')
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diff --git a/arch/arm/mach-pxa/time.c b/arch/arm/mach-pxa/time.c
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+/*
+ * arch/arm/mach-pxa/time.c
+ *
+ * Author: Nicolas Pitre
+ * Created: Jun 15, 2001
+ * Copyright: MontaVista Software Inc.
+ *
+ * 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/config.h>
+#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/sched.h>
+
+#include <asm/system.h>
+#include <asm/hardware.h>
+#include <asm/io.h>
+#include <asm/leds.h>
+#include <asm/irq.h>
+#include <asm/mach/irq.h>
+#include <asm/mach/time.h>
+#include <asm/arch/pxa-regs.h>
+
+
+static inline unsigned long pxa_get_rtc_time(void)
+{
+ return RCNR;
+}
+
+static int pxa_set_rtc(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;
+}
+
+/* IRQs are disabled before entering here from do_gettimeofday() */
+static unsigned long pxa_gettimeoffset (void)
+{
+ long ticks_to_match, elapsed, usec;
+
+ /* Get ticks before next timer match */
+ ticks_to_match = OSMR0 - OSCR;
+
+ /* We need elapsed ticks since last match */
+ elapsed = LATCH - ticks_to_match;
+
+ /* don't get fooled by the workaround in pxa_timer_interrupt() */
+ if (elapsed <= 0)
+ return 0;
+
+ /* Now convert them to usec */
+ usec = (unsigned long)(elapsed * (tick_nsec / 1000))/LATCH;
+
+ return usec;
+}
+
+static irqreturn_t
+pxa_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+ int next_match;
+
+ write_seqlock(&xtime_lock);
+
+ /* Loop until we get ahead of the free running timer.
+ * This ensures an exact clock tick count and time accuracy.
+ * IRQs are disabled inside the loop to ensure coherence between
+ * lost_ticks (updated in do_timer()) and the match reg value, so 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(regs);
+ OSSR = OSSR_M0; /* Clear match on timer 0 */
+ next_match = (OSMR0 += LATCH);
+ } while( (signed long)(next_match - OSCR) <= 8 );
+
+ write_sequnlock(&xtime_lock);
+
+ return IRQ_HANDLED;
+}
+
+static struct irqaction pxa_timer_irq = {
+ .name = "PXA Timer Tick",
+ .flags = SA_INTERRUPT,
+ .handler = pxa_timer_interrupt
+};
+
+static void __init pxa_timer_init(void)
+{
+ struct timespec tv;
+
+ set_rtc = pxa_set_rtc;
+
+ tv.tv_nsec = 0;
+ tv.tv_sec = pxa_get_rtc_time();
+ do_settimeofday(&tv);
+
+ OSMR0 = 0; /* set initial match at 0 */
+ OSSR = 0xf; /* clear status on all timers */
+ setup_irq(IRQ_OST0, &pxa_timer_irq);
+ OIER |= OIER_E0; /* enable match on timer 0 to cause interrupts */
+ OSCR = 0; /* initialize free-running timer, force first match */
+}
+
+#ifdef CONFIG_PM
+static unsigned long osmr[4], oier;
+
+static void pxa_timer_suspend(void)
+{
+ osmr[0] = OSMR0;
+ osmr[1] = OSMR1;
+ osmr[2] = OSMR2;
+ osmr[3] = OSMR3;
+ oier = OIER;
+}
+
+static void pxa_timer_resume(void)
+{
+ 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;
+}
+#else
+#define pxa_timer_suspend NULL
+#define pxa_timer_resume NULL
+#endif
+
+struct sys_timer pxa_timer = {
+ .init = pxa_timer_init,
+ .suspend = pxa_timer_suspend,
+ .resume = pxa_timer_resume,
+ .offset = pxa_gettimeoffset,
+};