1 files changed, 127 insertions, 0 deletions

diff --git a/arch/arm/mach-at91rm9200/time.c b/arch/arm/mach-at91rm9200/time.c
new file mode 100644
index 000000000000..1b6dd2deeb22
--- /dev/null
+++ b/arch/arm/mach-at91rm9200/time.c
@@ -0,0 +1,127 @@
+/*
+ * linux/arch/arm/mach-at91rm9200/time.c
+ *
+ *  Copyright (C) 2003 SAN People
+ *  Copyright (C) 2003 ATMEL
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/config.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/time.h>
+
+#include <asm/hardware.h>
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <asm/mach/time.h>
+
+/*
+ * The ST_CRTR is updated asynchronously to the master clock.  It is therefore
+ *  necessary to read it twice (with the same value) to ensure accuracy.
+ */
+static inline unsigned long read_CRTR(void) {
+        unsigned long x1, x2;
+
+        do {
+                x1 = at91_sys_read(AT91_ST_CRTR);
+                x2 = at91_sys_read(AT91_ST_CRTR);
+        } while (x1 != x2);
+
+        return x1;
+}
+
+/*
+ * Returns number of microseconds since last timer interrupt.  Note that interrupts
+ * will have been disabled by do_gettimeofday()
+ *  'LATCH' is hwclock ticks (see CLOCK_TICK_RATE in timex.h) per jiffy.
+ *  'tick' is usecs per jiffy (linux/timex.h).
+ */
+static unsigned long at91rm9200_gettimeoffset(void)
+{
+        unsigned long elapsed;
+
+        elapsed = (read_CRTR() - at91_sys_read(AT91_ST_RTAR)) & AT91_ST_ALMV;
+
+        return (unsigned long)(elapsed * (tick_nsec / 1000)) / LATCH;
+}
+
+/*
+ * IRQ handler for the timer.
+ */
+static irqreturn_t at91rm9200_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+        unsigned long rtar;
+
+        if (at91_sys_read(AT91_ST_SR) & AT91_ST_PITS) { /* This is a shared interrupt */
+                write_seqlock(&xtime_lock);
+
+                do {
+                        timer_tick(regs);
+                        rtar = (at91_sys_read(AT91_ST_RTAR) + LATCH) & AT91_ST_ALMV;
+                        at91_sys_write(AT91_ST_RTAR, rtar);
+                } while (((read_CRTR() - at91_sys_read(AT91_ST_RTAR)) & AT91_ST_ALMV) >= LATCH);
+
+                write_sequnlock(&xtime_lock);
+
+                return IRQ_HANDLED;
+        }
+        else
+                return IRQ_NONE;                /* not handled */
+}
+
+static struct irqaction at91rm9200_timer_irq = {
+        .name           = "at91_tick",
+        .flags          = SA_SHIRQ | SA_INTERRUPT,
+        .handler        = at91rm9200_timer_interrupt
+};
+
+/*
+ * Set up timer interrupt.
+ */
+void __init at91rm9200_timer_init(void)
+{
+        /* Disable all timer interrupts */
+        at91_sys_write(AT91_ST_IDR, AT91_ST_PITS | AT91_ST_WDOVF | AT91_ST_RTTINC | AT91_ST_ALMS);
+        (void) at91_sys_read(AT91_ST_SR);       /* Clear any pending interrupts */
+
+        /*
+         * Make IRQs happen for the system timer.
+         */
+        setup_irq(AT91_ID_SYS, &at91rm9200_timer_irq);
+
+        /* Set initial alarm to 0 */
+        at91_sys_write(AT91_ST_RTAR, 0);
+
+        /* Real time counter incremented every 30.51758 microseconds */
+        at91_sys_write(AT91_ST_RTMR, 1);
+
+        /* Set Period Interval timer */
+        at91_sys_write(AT91_ST_PIMR, LATCH);
+
+        /* Change the kernel's 'tick' value to 10009 usec. (the default is 10000) */
+        tick_usec = (LATCH * 1000000) / CLOCK_TICK_RATE;
+
+        /* Enable Period Interval Timer interrupt */
+        at91_sys_write(AT91_ST_IER, AT91_ST_PITS);
+}
+
+struct sys_timer at91rm9200_timer = {
+        .init           = at91rm9200_timer_init,
+        .offset         = at91rm9200_gettimeoffset,
+};