patch-2.3.99-pre8 linux/include/asm-arm/arch-sa1100/time.h

• Lines: 61
• Date: Fri May 12 11:21:20 2000
• Orig file: v2.3.99-pre7/linux/include/asm-arm/arch-sa1100/time.h
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.99-pre7/linux/include/asm-arm/arch-sa1100/time.h linux/include/asm-arm/arch-sa1100/time.h
@@ -0,0 +1,60 @@
+/*
+ * linux/include/asm-arm/arch-sa1100/time.h
+ *
+ * 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 acuracy.
+ *
+ */
+
+#include <asm/arch/hardware.h>
+#include <asm/arch/irqs.h>
+
+
+/* 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)/LATCH;
+
+	return usec;
+}
+
+
+static void sa1100_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 acuracy.
+	 * Should be IRQ race free.
+	 */
+	do {
+		do_timer(regs);
+		OSSR = OSSR_M0;  /* Clear match on timer 0 */
+		next_match = (OSMR0 += LATCH);
+	} while( (signed long)(next_match - OSCR) <= 0 );
+}
+
+
+extern inline void setup_timer (void)
+{
+	gettimeoffset = sa1100_gettimeoffset;
+	timer_irq.handler = sa1100_timer_interrupt;
+	OSMR0 = 0;		/* set initial match at 0 */
+	OSSR = 0xf;		/* clear status on all timers */
+	setup_arm_irq(IRQ_OST0, &timer_irq);
+	OIER |= OIER_E0;	/* enable match on timer 0 to cause interrupts */
+	OSCR = 0;		/* initialize free-running timer, force first match */
+}
+