aboutsummaryrefslogtreecommitdiff
path: root/arch/arm/mach-sa1100/time.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arm/mach-sa1100/time.c')
-rw-r--r--arch/arm/mach-sa1100/time.c159
1 files changed, 159 insertions, 0 deletions
diff --git a/arch/arm/mach-sa1100/time.c b/arch/arm/mach-sa1100/time.c
new file mode 100644
index 000000000000..19b0c0fd6377
--- /dev/null
+++ b/arch/arm/mach-sa1100/time.c
@@ -0,0 +1,159 @@
+/*
+ * linux/arch/arm/mach-sa1100/time.c
+ *
+ * Copyright (C) 1998 Deborah Wallach.
+ * Twiddles (C) 1999 Hugo Fiennes <hugo@empeg.com>
+ *
+ * 2000/03/29 (C) Nicolas Pitre <nico@cam.org>
+ * Rewritten: big cleanup, much simpler, better HZ accuracy.
+ *
+ */
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/timex.h>
+#include <linux/signal.h>
+
+#include <asm/mach/time.h>
+#include <asm/hardware.h>
+
+#define RTC_DEF_DIVIDER (32768 - 1)
+#define RTC_DEF_TRIM 0
+
+static unsigned long __init sa1100_get_rtc_time(void)
+{
+ /*
+ * According to the manual we should be able to let RTTR be zero
+ * and then a default diviser for a 32.768KHz clock is used.
+ * Apparently this doesn't work, at least for my SA1110 rev 5.
+ * If the clock divider is uninitialized then reset it to the
+ * default value to get the 1Hz clock.
+ */
+ if (RTTR == 0) {
+ RTTR = RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16);
+ printk(KERN_WARNING "Warning: uninitialized Real Time Clock\n");
+ /* The current RTC value probably doesn't make sense either */
+ RCNR = 0;
+ return 0;
+ }
+ return RCNR;
+}
+
+static int sa1100_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 sa1100_gettimeoffset (void)
+{
+ unsigned 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;
+
+ /* Now convert them to usec */
+ usec = (unsigned long)(elapsed * (tick_nsec / 1000))/LATCH;
+
+ return usec;
+}
+
+/*
+ * We will be entered with IRQs enabled.
+ *
+ * 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.
+ */
+static irqreturn_t
+sa1100_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+ unsigned int next_match;
+
+ write_seqlock(&xtime_lock);
+
+ do {
+ timer_tick(regs);
+ OSSR = OSSR_M0; /* Clear match on timer 0 */
+ next_match = (OSMR0 += LATCH);
+ } while ((signed long)(next_match - OSCR) <= 0);
+
+ write_sequnlock(&xtime_lock);
+
+ return IRQ_HANDLED;
+}
+
+static struct irqaction sa1100_timer_irq = {
+ .name = "SA11xx Timer Tick",
+ .flags = SA_INTERRUPT,
+ .handler = sa1100_timer_interrupt
+};
+
+static void __init sa1100_timer_init(void)
+{
+ struct timespec tv;
+
+ set_rtc = sa1100_set_rtc;
+
+ tv.tv_nsec = 0;
+ tv.tv_sec = sa1100_get_rtc_time();
+ do_settimeofday(&tv);
+
+ OSMR0 = 0; /* set initial match at 0 */
+ OSSR = 0xf; /* clear status on all timers */
+ setup_irq(IRQ_OST0, &sa1100_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
+unsigned long osmr[4], oier;
+
+static void sa1100_timer_suspend(void)
+{
+ osmr[0] = OSMR0;
+ osmr[1] = OSMR1;
+ osmr[2] = OSMR2;
+ osmr[3] = OSMR3;
+ oier = OIER;
+}
+
+static void sa1100_timer_resume(void)
+{
+ OSSR = 0x0f;
+ 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 sa1100_timer_suspend NULL
+#define sa1100_timer_resume NULL
+#endif
+
+struct sys_timer sa1100_timer = {
+ .init = sa1100_timer_init,
+ .suspend = sa1100_timer_suspend,
+ .resume = sa1100_timer_resume,
+ .offset = sa1100_gettimeoffset,
+};