1 files changed, 94 insertions, 0 deletions
diff --git a/arch/arm/mach-footbridge/isa-timer.c b/arch/arm/mach-footbridge/isa-timer.c
new file mode 100644
index 000000000000..a4fefa0bb5a1
--- /dev/null
+++ b/arch/arm/mach-footbridge/isa-timer.c
@@ -0,0 +1,94 @@
+/*
+ *  linux/arch/arm/mach-footbridge/isa-timer.c
+ *
+ *  Copyright (C) 1998 Russell King.
+ *  Copyright (C) 1998 Phil Blundell
+ */
+#include <linux/init.h>
+#include <linux/interrupt.h>
+
+#include <asm/io.h>
+#include <asm/irq.h>
+
+#include <asm/mach/time.h>
+
+#include "common.h"
+
+/*
+ * ISA timer tick support
+ */
+#define mSEC_10_from_14 ((14318180 + 100) / 200)
+
+static unsigned long isa_gettimeoffset(void)
+{
+	int count;
+
+	static int count_p = (mSEC_10_from_14/6);    /* for the first call after boot */
+	static unsigned long jiffies_p = 0;
+
+	/*
+	 * cache volatile jiffies temporarily; we have IRQs turned off. 
+	 */
+	unsigned long jiffies_t;
+
+	/* timer count may underflow right here */
+	outb_p(0x00, 0x43);	/* latch the count ASAP */
+
+	count = inb_p(0x40);	/* read the latched count */
+
+	/*
+	 * We do this guaranteed double memory access instead of a _p 
+	 * postfix in the previous port access. Wheee, hackady hack
+	 */
+ 	jiffies_t = jiffies;
+
+	count |= inb_p(0x40) << 8;
+
+	/* Detect timer underflows.  If we haven't had a timer tick since 
+	   the last time we were called, and time is apparently going
+	   backwards, the counter must have wrapped during this routine. */
+	if ((jiffies_t == jiffies_p) && (count > count_p))
+		count -= (mSEC_10_from_14/6);
+	else
+		jiffies_p = jiffies_t;
+
+	count_p = count;
+
+	count = (((mSEC_10_from_14/6)-1) - count) * (tick_nsec / 1000);
+	count = (count + (mSEC_10_from_14/6)/2) / (mSEC_10_from_14/6);
+
+	return count;
+}
+
+static irqreturn_t
+isa_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+	write_seqlock(&xtime_lock);
+	timer_tick(regs);
+	write_sequnlock(&xtime_lock);
+	return IRQ_HANDLED;
+}
+
+static struct irqaction isa_timer_irq = {
+	.name		= "ISA timer tick",
+	.handler	= isa_timer_interrupt,
+	.flags		= SA_INTERRUPT,
+};
+
+static void __init isa_timer_init(void)
+{
+	isa_rtc_init();
+
+	/* enable PIT timer */
+	/* set for periodic (4) and LSB/MSB write (0x30) */
+	outb(0x34, 0x43);
+	outb((mSEC_10_from_14/6) & 0xFF, 0x40);
+	outb((mSEC_10_from_14/6) >> 8, 0x40);
+
+	setup_irq(IRQ_ISA_TIMER, &isa_timer_irq);
+}
+
+struct sys_timer isa_timer = {
+	.init		= isa_timer_init,
+	.offset		= isa_gettimeoffset,
+};