[ARM] 3949/2: AT91: SAM9 timer driver

Add support for the timer on the Atmel AT91SAM9261 and AT91SAM9260
processors.

Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 114 insertions, 0 deletions

diff --git a/arch/arm/mach-at91rm9200/at91sam926x_time.c b/arch/arm/mach-at91rm9200/at91sam926x_time.c
new file mode 100644
index 000000000000..99df5f6ee42e
--- /dev/null
+++ b/arch/arm/mach-at91rm9200/at91sam926x_time.c
@@ -0,0 +1,114 @@
+/*
+ * linux/arch/arm/mach-at91rm9200/at91sam926x_time.c
+ *
+ * Copyright (C) 2005-2006 M. Amine SAYA, ATMEL Rousset, France
+ * Revision      2005 M. Nicolas Diremdjian, ATMEL Rousset, France
+ *
+ * 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/init.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/time.h>
+
+#include <asm/hardware.h>
+#include <asm/io.h>
+#include <asm/mach/time.h>
+
+#include <asm/arch/at91_pit.h>
+
+
+#define PIT_CPIV(x)     ((x) & AT91_PIT_CPIV)
+#define PIT_PICNT(x)    (((x) & AT91_PIT_PICNT) >> 20)
+
+/*
+ * 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 at91sam926x_gettimeoffset(void)
+{
+        unsigned long elapsed;
+        unsigned long t = at91_sys_read(AT91_PIT_PIIR);
+
+        elapsed = (PIT_PICNT(t) * LATCH) + PIT_CPIV(t);         /* hardware clock cycles */
+
+        return (unsigned long)(elapsed * 1000000) / LATCH;
+}
+
+/*
+ * IRQ handler for the timer.
+ */
+static irqreturn_t at91sam926x_timer_interrupt(int irq, void *dev_id)
+{
+        volatile long nr_ticks;
+
+        if (at91_sys_read(AT91_PIT_SR) & AT91_PIT_PITS) {       /* This is a shared interrupt */
+                write_seqlock(&xtime_lock);
+
+                /* Get number to ticks performed before interrupt and clear PIT interrupt */
+                nr_ticks = PIT_PICNT(at91_sys_read(AT91_PIT_PIVR));
+                do {
+                        timer_tick();
+                        nr_ticks--;
+                } while (nr_ticks);
+
+                write_sequnlock(&xtime_lock);
+                return IRQ_HANDLED;
+        } else
+                return IRQ_NONE;                /* not handled */
+}
+
+static struct irqaction at91sam926x_timer_irq = {
+        .name           = "at91_tick",
+        .flags          = IRQF_SHARED | IRQF_DISABLED | IRQF_TIMER,
+        .handler        = at91sam926x_timer_interrupt
+};
+
+void at91sam926x_timer_reset(void)
+{
+        /* Disable timer */
+        at91_sys_write(AT91_PIT_MR, 0);
+
+        /* Clear any pending interrupts */
+        (void) at91_sys_read(AT91_PIT_PIVR);
+
+        /* Set Period Interval timer and enable its interrupt */
+        at91_sys_write(AT91_PIT_MR, (LATCH & AT91_PIT_PIV) | AT91_PIT_PITIEN | AT91_PIT_PITEN);
+}
+
+/*
+ * Set up timer interrupt.
+ */
+void __init at91sam926x_timer_init(void)
+{
+        /* Initialize and enable the timer */
+        at91sam926x_timer_reset();
+
+        /* Make IRQs happen for the system timer. */
+        setup_irq(AT91_ID_SYS, &at91sam926x_timer_irq);
+}
+
+#ifdef CONFIG_PM
+static void at91sam926x_timer_suspend(void)
+{
+        /* Disable timer */
+        at91_sys_write(AT91_PIT_MR, 0);
+}
+#else
+#define at91sam926x_timer_suspend       NULL
+#endif
+
+struct sys_timer at91sam926x_timer = {
+        .init           = at91sam926x_timer_init,
+        .offset         = at91sam926x_gettimeoffset,
+        .suspend        = at91sam926x_timer_suspend,
+        .resume         = at91sam926x_timer_reset,
+};
+