This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / arch / arm / mach-pxa / time.c

diff --git a/arch/arm/mach-pxa/time.c b/arch/arm/mach-pxa/time.c
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+++ 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>
+
+
+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;
+
+       /* 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 );
+
+       return IRQ_HANDLED;
+}
+
+static struct irqaction pxa_timer_irq = {
+       .name           = "PXA Timer Tick",
+       .flags          = SA_INTERRUPT,
+       .handler        = pxa_timer_interrupt
+};
+
+void __init pxa_init_time(void)
+{
+       struct timespec tv;
+
+       gettimeoffset = pxa_gettimeoffset;
+       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 */
+}
+